move additional release missed in last commit

Move 2023/4 changelog entries under docs/changelogs
move postgres changelog to the top
2025-01-14 14:23:35 +00:00 · 2025-01-14 14:20:08 +00:00 · 2025-01-14 14:17:55 +00:00 · 2025-01-14 14:14:23 +00:00 · 2025-01-07 17:43:41 +00:00 · 2025-01-07 15:20:24 +00:00
249 changed files with 13257 additions and 5628 deletions
--- a/.ci/scripts/calculate_jobs.py
+++ b/.ci/scripts/calculate_jobs.py
@@ -36,11 +36,11 @@ IS_PR = os.environ["GITHUB_REF"].startswith("refs/pull/")
 # First calculate the various trial jobs.
 #
 # For PRs, we only run each type of test with the oldest Python version supported (which
-# is Python 3.8 right now)
+# is Python 3.9 right now)

 trial_sqlite_tests = [
    {
-        "python-version": "3.8",
+        "python-version": "3.9",
        "database": "sqlite",
        "extras": "all",
    }
@@ -53,14 +53,14 @@ if not IS_PR:
            "database": "sqlite",
            "extras": "all",
        }
-        for version in ("3.9", "3.10", "3.11", "3.12")
+        for version in ("3.10", "3.11", "3.12", "3.13")
    )

 trial_postgres_tests = [
    {
-        "python-version": "3.8",
+        "python-version": "3.9",
        "database": "postgres",
-        "postgres-version": "11",
+        "postgres-version": "13",
        "extras": "all",
    }
 ]
@@ -68,16 +68,16 @@ trial_postgres_tests = [
 if not IS_PR:
    trial_postgres_tests.append(
        {
-            "python-version": "3.12",
+            "python-version": "3.13",
            "database": "postgres",
-            "postgres-version": "16",
+            "postgres-version": "17",
            "extras": "all",
        }
    )

 trial_no_extra_tests = [
    {
-        "python-version": "3.8",
+        "python-version": "3.9",
        "database": "sqlite",
        "extras": "",
    }
@@ -99,24 +99,24 @@ set_output("trial_test_matrix", test_matrix)

 # First calculate the various sytest jobs.
 #
-# For each type of test we only run on focal on PRs
+# For each type of test we only run on bullseye on PRs


 sytest_tests = [
    {
-        "sytest-tag": "focal",
+        "sytest-tag": "bullseye",
    },
    {
-        "sytest-tag": "focal",
+        "sytest-tag": "bullseye",
        "postgres": "postgres",
    },
    {
-        "sytest-tag": "focal",
+        "sytest-tag": "bullseye",
        "postgres": "multi-postgres",
        "workers": "workers",
    },
    {
-        "sytest-tag": "focal",
+        "sytest-tag": "bullseye",
        "postgres": "multi-postgres",
        "workers": "workers",
        "reactor": "asyncio",
@@ -127,11 +127,11 @@ if not IS_PR:
    sytest_tests.extend(
        [
            {
-                "sytest-tag": "focal",
+                "sytest-tag": "bullseye",
                "reactor": "asyncio",
            },
            {
-                "sytest-tag": "focal",
+                "sytest-tag": "bullseye",
                "postgres": "postgres",
                "reactor": "asyncio",
            },
--- a/.ci/scripts/prepare_old_deps.sh
+++ b/.ci/scripts/prepare_old_deps.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# this script is run by GitHub Actions in a plain `focal` container; it
+# this script is run by GitHub Actions in a plain `jammy` container; it
 # - installs the minimal system requirements, and poetry;
 # - patches the project definition file to refer to old versions only;
 # - creates a venv with these old versions using poetry; and finally
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -14,7 +14,7 @@ permissions:
  id-token: write # needed for signing the images with GitHub OIDC Token
 jobs:
  build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
    steps:
      - name: Set up QEMU
        id: qemu
@@ -30,7 +30,7 @@ jobs:
        run: docker buildx inspect

      - name: Install Cosign
-        uses: sigstore/cosign-installer@v3.6.0
+        uses: sigstore/cosign-installer@v3.7.0

      - name: Checkout repository
        uses: actions/checkout@v4
--- a/.github/workflows/docs-pr-netlify.yaml
+++ b/.github/workflows/docs-pr-netlify.yaml
@@ -14,7 +14,7 @@ jobs:
      # There's a 'download artifact' action, but it hasn't been updated for the workflow_run action
      # (https://github.com/actions/download-artifact/issues/60) so instead we get this mess:
      - name: 📥 Download artifact
-        uses: dawidd6/action-download-artifact@bf251b5aa9c2f7eeb574a96ee720e24f801b7c11 # v6
+        uses: dawidd6/action-download-artifact@80620a5d27ce0ae443b965134db88467fc607b43 # v7
        with:
          workflow: docs-pr.yaml
          run_id: ${{ github.event.workflow_run.id }}
--- a/.github/workflows/latest_deps.yml
+++ b/.github/workflows/latest_deps.yml
@@ -132,9 +132,9 @@ jobs:
      fail-fast: false
      matrix:
        include:
-          - sytest-tag: focal
+          - sytest-tag: bullseye

-          - sytest-tag: focal
+          - sytest-tag: bullseye
            postgres: postgres
            workers: workers
            redis: redis
--- a/.github/workflows/release-artifacts.yml
+++ b/.github/workflows/release-artifacts.yml
@@ -91,10 +91,19 @@ jobs:
          rm -rf /tmp/.buildx-cache
          mv /tmp/.buildx-cache-new /tmp/.buildx-cache

+      - name: Artifact name
+        id: artifact-name
+        # We can't have colons in the upload name of the artifact, so we convert
+        # e.g. `debian:sid` to `sid`.
+        env:
+          DISTRO: ${{ matrix.distro }}
+        run: |
+          echo "ARTIFACT_NAME=${DISTRO#*:}" >> "$GITHUB_OUTPUT"
+
      - name: Upload debs as artifacts
-        uses: actions/upload-artifact@v3 # Don't upgrade to v4; broken: https://github.com/actions/upload-artifact#breaking-changes
+        uses: actions/upload-artifact@v4
        with:
-          name: debs
+          name: debs-${{ steps.artifact-name.outputs.ARTIFACT_NAME }}
          path: debs/*

  build-wheels:
@@ -102,7 +111,7 @@ jobs:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
-        os: [ubuntu-20.04, macos-12]
+        os: [ubuntu-22.04, macos-13]
        arch: [x86_64, aarch64]
        # is_pr is a flag used to exclude certain jobs from the matrix on PRs.
        # It is not read by the rest of the workflow.
@@ -112,9 +121,9 @@ jobs:
        exclude:
          # Don't build macos wheels on PR CI.
          - is_pr: true
-            os: "macos-12"
+            os: "macos-13"
          # Don't build aarch64 wheels on mac.
-          - os: "macos-12"
+          - os: "macos-13"
            arch: aarch64
          # Don't build aarch64 wheels on PR CI.
          - is_pr: true
@@ -144,7 +153,7 @@ jobs:

      - name: Only build a single wheel on PR
        if: startsWith(github.ref, 'refs/pull/')
-        run: echo "CIBW_BUILD="cp38-manylinux_${{ matrix.arch }}"" >> $GITHUB_ENV
+        run: echo "CIBW_BUILD="cp39-manylinux_${{ matrix.arch }}"" >> $GITHUB_ENV

      - name: Build wheels
        run: python -m cibuildwheel --output-dir wheelhouse
@@ -156,9 +165,9 @@ jobs:
          CARGO_NET_GIT_FETCH_WITH_CLI: true
          CIBW_ENVIRONMENT_PASS_LINUX: CARGO_NET_GIT_FETCH_WITH_CLI

-      - uses: actions/upload-artifact@v3 # Don't upgrade to v4; broken: https://github.com/actions/upload-artifact#breaking-changes
+      - uses: actions/upload-artifact@v4
        with:
-          name: Wheel
+          name: Wheel-${{ matrix.os }}-${{ matrix.arch }}
          path: ./wheelhouse/*.whl

  build-sdist:
@@ -177,7 +186,7 @@ jobs:
      - name: Build sdist
        run: python -m build --sdist

-      - uses: actions/upload-artifact@v3 # Don't upgrade to v4; broken: https://github.com/actions/upload-artifact#breaking-changes
+      - uses: actions/upload-artifact@v4
        with:
          name: Sdist
          path: dist/*.tar.gz
@@ -194,17 +203,23 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Download all workflow run artifacts
-        uses: actions/download-artifact@v3 # Don't upgrade to v4, it should match upload-artifact
+        uses: actions/download-artifact@v4
      - name: Build a tarball for the debs
-        run: tar -cvJf debs.tar.xz debs
+        # We need to merge all the debs uploads into one folder, then compress
+        # that.
+        run: |
+          mkdir debs
+          mv debs*/* debs/
+          tar -cvJf debs.tar.xz debs
      - name: Attach to release
-        uses: softprops/action-gh-release@a929a66f232c1b11af63782948aa2210f981808a  # PR#109
+        # Pinned to work around https://github.com/softprops/action-gh-release/issues/445
+        uses: softprops/action-gh-release@v0.1.15
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          files: |
            Sdist/*
-            Wheel/*
+            Wheel*/*
            debs.tar.xz
          # if it's not already published, keep the release as a draft.
          draft: true
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -397,7 +397,7 @@ jobs:
    needs:
      - linting-done
      - changes
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
    steps:
      - uses: actions/checkout@v4

@@ -409,12 +409,12 @@ jobs:
      # their build dependencies
      - run: |
          sudo apt-get -qq update
-          sudo apt-get -qq install build-essential libffi-dev python-dev \
+          sudo apt-get -qq install build-essential libffi-dev python3-dev \
            libxml2-dev libxslt-dev xmlsec1 zlib1g-dev libjpeg-dev libwebp-dev

      - uses: actions/setup-python@v5
        with:
-          python-version: '3.8'
+          python-version: '3.9'

      - name: Prepare old deps
        if: steps.cache-poetry-old-deps.outputs.cache-hit != 'true'
@@ -458,7 +458,7 @@ jobs:
    runs-on: ubuntu-latest
    strategy:
      matrix:
-        python-version: ["pypy-3.8"]
+        python-version: ["pypy-3.9"]
        extras: ["all"]

    steps:
@@ -580,11 +580,11 @@ jobs:
    strategy:
      matrix:
        include:
-          - python-version: "3.8"
-            postgres-version: "11"
+          - python-version: "3.9"
+            postgres-version: "13"

-          - python-version: "3.11"
-            postgres-version: "15"
+          - python-version: "3.13"
+            postgres-version: "17"

    services:
      postgres:
--- a/.github/workflows/twisted_trunk.yml
+++ b/.github/workflows/twisted_trunk.yml
@@ -99,11 +99,11 @@ jobs:
    if: needs.check_repo.outputs.should_run_workflow == 'true'
    runs-on: ubuntu-latest
    container:
-      # We're using ubuntu:focal because it uses Python 3.8 which is our minimum supported Python version.
+      # We're using debian:bullseye because it uses Python 3.9 which is our minimum supported Python version.
      # This job is a canary to warn us about unreleased twisted changes that would cause problems for us if
      # they were to be released immediately. For simplicity's sake (and to save CI runners) we use the oldest
      # version, assuming that any incompatibilities on newer versions would also be present on the oldest.
-      image: matrixdotorg/sytest-synapse:focal
+      image: matrixdotorg/sytest-synapse:bullseye
      volumes:
        - ${{ github.workspace }}:/src

--- a/CHANGES.md
+++ b/CHANGES.md
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -13,9 +13,9 @@ dependencies = [

 [[package]]
 name = "anyhow"
-version = "1.0.89"
+version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86fdf8605db99b54d3cd748a44c6d04df638eb5dafb219b135d0149bd0db01f6"
+checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"

 [[package]]
 name = "arc-swap"
@@ -35,12 +35,6 @@ version = "0.21.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9d297deb1925b89f2ccc13d7635fa0714f12c87adce1c75356b39ca9b7178567"

-[[package]]
-name = "bitflags"
-version = "2.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf4b9d6a944f767f8e5e0db018570623c85f3d925ac718db4e06d0187adb21c1"
-
 [[package]]
 name = "blake2"
 version = "0.10.6"
@@ -67,9 +61,9 @@ checksum = "79296716171880943b8470b5f8d03aa55eb2e645a4874bdbb28adb49162e012c"

 [[package]]
 name = "bytes"
-version = "1.7.2"
+version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "428d9aa8fbc0670b7b8d6030a7fadd0f86151cae55e4dbbece15f3780a3dfaf3"
+checksum = "325918d6fe32f23b19878fe4b34794ae41fc19ddbe53b10571a4874d44ffd39b"

 [[package]]
 name = "cfg-if"
@@ -162,9 +156,9 @@ dependencies = [

 [[package]]
 name = "heck"
-version = "0.4.1"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
+checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"

 [[package]]
 name = "hex"
@@ -174,9 +168,9 @@ checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"

 [[package]]
 name = "http"
-version = "1.1.0"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "21b9ddb458710bc376481b842f5da65cdf31522de232c1ca8146abce2a358258"
+checksum = "f16ca2af56261c99fba8bac40a10251ce8188205a4c448fbb745a2e4daa76fea"
 dependencies = [
 "bytes",
 "fnv",
@@ -222,16 +216,6 @@ version = "0.2.154"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ae743338b92ff9146ce83992f766a31066a91a8c84a45e0e9f21e7cf6de6d346"

-[[package]]
-name = "lock_api"
-version = "0.4.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07af8b9cdd281b7915f413fa73f29ebd5d55d0d3f0155584dade1ff18cea1b17"
-dependencies = [
- "autocfg",
- "scopeguard",
-]
-
 [[package]]
 name = "log"
 version = "0.4.22"
@@ -265,29 +249,6 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"

-[[package]]
-name = "parking_lot"
-version = "0.12.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e4af0ca4f6caed20e900d564c242b8e5d4903fdacf31d3daf527b66fe6f42fb"
-dependencies = [
- "lock_api",
- "parking_lot_core",
-]
-
-[[package]]
-name = "parking_lot_core"
-version = "0.9.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e401f977ab385c9e4e3ab30627d6f26d00e2c73eef317493c4ec6d468726cf8"
-dependencies = [
- "cfg-if",
- "libc",
- "redox_syscall",
- "smallvec",
- "windows-targets",
-]
-
 [[package]]
 name = "portable-atomic"
 version = "1.6.0"
@@ -302,25 +263,25 @@ checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"

 [[package]]
 name = "proc-macro2"
-version = "1.0.82"
+version = "1.0.89"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ad3d49ab951a01fbaafe34f2ec74122942fe18a3f9814c3268f1bb72042131b"
+checksum = "f139b0662de085916d1fb67d2b4169d1addddda1919e696f3252b740b629986e"
 dependencies = [
 "unicode-ident",
 ]

 [[package]]
 name = "pyo3"
-version = "0.21.2"
+version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5e00b96a521718e08e03b1a622f01c8a8deb50719335de3f60b3b3950f069d8"
+checksum = "e484fd2c8b4cb67ab05a318f1fd6fa8f199fcc30819f08f07d200809dba26c15"
 dependencies = [
 "anyhow",
 "cfg-if",
 "indoc",
 "libc",
 "memoffset",
- "parking_lot",
+ "once_cell",
 "portable-atomic",
 "pyo3-build-config",
 "pyo3-ffi",
@@ -330,9 +291,9 @@ dependencies = [

 [[package]]
 name = "pyo3-build-config"
-version = "0.21.2"
+version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7883df5835fafdad87c0d888b266c8ec0f4c9ca48a5bed6bbb592e8dedee1b50"
+checksum = "dc0e0469a84f208e20044b98965e1561028180219e35352a2afaf2b942beff3b"
 dependencies = [
 "once_cell",
 "target-lexicon",
@@ -340,9 +301,9 @@ dependencies = [

 [[package]]
 name = "pyo3-ffi"
-version = "0.21.2"
+version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01be5843dc60b916ab4dad1dca6d20b9b4e6ddc8e15f50c47fe6d85f1fb97403"
+checksum = "eb1547a7f9966f6f1a0f0227564a9945fe36b90da5a93b3933fc3dc03fae372d"
 dependencies = [
 "libc",
 "pyo3-build-config",
@@ -350,9 +311,9 @@ dependencies = [

 [[package]]
 name = "pyo3-log"
-version = "0.10.0"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2af49834b8d2ecd555177e63b273b708dea75150abc6f5341d0a6e1a9623976c"
+checksum = "3eb421dc86d38d08e04b927b02424db480be71b777fa3a56f32e2f2a3a1a3b08"
 dependencies = [
 "arc-swap",
 "log",
@@ -361,9 +322,9 @@ dependencies = [

 [[package]]
 name = "pyo3-macros"
-version = "0.21.2"
+version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77b34069fc0682e11b31dbd10321cbf94808394c56fd996796ce45217dfac53c"
+checksum = "fdb6da8ec6fa5cedd1626c886fc8749bdcbb09424a86461eb8cdf096b7c33257"
 dependencies = [
 "proc-macro2",
 "pyo3-macros-backend",
@@ -373,9 +334,9 @@ dependencies = [

 [[package]]
 name = "pyo3-macros-backend"
-version = "0.21.2"
+version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08260721f32db5e1a5beae69a55553f56b99bd0e1c3e6e0a5e8851a9d0f5a85c"
+checksum = "38a385202ff5a92791168b1136afae5059d3ac118457bb7bc304c197c2d33e7d"
 dependencies = [
 "heck",
 "proc-macro2",
@@ -386,9 +347,9 @@ dependencies = [

 [[package]]
 name = "pythonize"
-version = "0.21.1"
+version = "0.23.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9d0664248812c38cc55a4ed07f88e4df516ce82604b93b1ffdc041aa77a6cb3c"
+checksum = "91a6ee7a084f913f98d70cdc3ebec07e852b735ae3059a1500db2661265da9ff"
 dependencies = [
 "pyo3",
 "serde",
@@ -433,20 +394,11 @@ dependencies = [
 "getrandom",
 ]

-[[package]]
-name = "redox_syscall"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "469052894dcb553421e483e4209ee581a45100d31b4018de03e5a7ad86374a7e"
-dependencies = [
- "bitflags",
-]
-
 [[package]]
 name = "regex"
-version = "1.10.6"
+version = "1.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4219d74c6b67a3654a9fbebc4b419e22126d13d2f3c4a07ee0cb61ff79a79619"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
 dependencies = [
 "aho-corasick",
 "memchr",
@@ -456,9 +408,9 @@ dependencies = [

 [[package]]
 name = "regex-automata"
-version = "0.4.6"
+version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86b83b8b9847f9bf95ef68afb0b8e6cdb80f498442f5179a29fad448fcc1eaea"
+checksum = "368758f23274712b504848e9d5a6f010445cc8b87a7cdb4d7cbee666c1288da3"
 dependencies = [
 "aho-corasick",
 "memchr",
@@ -467,9 +419,9 @@ dependencies = [

 [[package]]
 name = "regex-syntax"
-version = "0.8.3"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "adad44e29e4c806119491a7f06f03de4d1af22c3a680dd47f1e6e179439d1f56"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"

 [[package]]
 name = "ryu"
@@ -477,26 +429,20 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"

-[[package]]
-name = "scopeguard"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
-
 [[package]]
 name = "serde"
-version = "1.0.210"
+version = "1.0.217"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c8e3592472072e6e22e0a54d5904d9febf8508f65fb8552499a1abc7d1078c3a"
+checksum = "02fc4265df13d6fa1d00ecff087228cc0a2b5f3c0e87e258d8b94a156e984c70"
 dependencies = [
 "serde_derive",
 ]

 [[package]]
 name = "serde_derive"
-version = "1.0.210"
+version = "1.0.217"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "243902eda00fad750862fc144cea25caca5e20d615af0a81bee94ca738f1df1f"
+checksum = "5a9bf7cf98d04a2b28aead066b7496853d4779c9cc183c440dbac457641e19a0"
 dependencies = [
 "proc-macro2",
 "quote",
@@ -505,9 +451,9 @@ dependencies = [

 [[package]]
 name = "serde_json"
-version = "1.0.128"
+version = "1.0.134"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ff5456707a1de34e7e37f2a6fd3d3f808c318259cbd01ab6377795054b483d8"
+checksum = "d00f4175c42ee48b15416f6193a959ba3a0d67fc699a0db9ad12df9f83991c7d"
 dependencies = [
 "itoa",
 "memchr",
@@ -537,12 +483,6 @@ dependencies = [
 "digest",
 ]

-[[package]]
-name = "smallvec"
-version = "1.13.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
-
 [[package]]
 name = "subtle"
 version = "2.5.0"
@@ -551,9 +491,9 @@ checksum = "81cdd64d312baedb58e21336b31bc043b77e01cc99033ce76ef539f78e965ebc"

 [[package]]
 name = "syn"
-version = "2.0.61"
+version = "2.0.85"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c993ed8ccba56ae856363b1845da7266a7cb78e1d146c8a32d54b45a8b831fc9"
+checksum = "5023162dfcd14ef8f32034d8bcd4cc5ddc61ef7a247c024a33e24e1f24d21b56"
 dependencies = [
 "proc-macro2",
 "quote",
@@ -694,67 +634,3 @@ dependencies = [
 "js-sys",
 "wasm-bindgen",
 ]
-
-[[package]]
-name = "windows-targets"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f0713a46559409d202e70e28227288446bf7841d3211583a4b53e3f6d96e7eb"
-dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
-]
-
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7088eed71e8b8dda258ecc8bac5fb1153c5cffaf2578fc8ff5d61e23578d3263"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9985fd1504e250c615ca5f281c3f7a6da76213ebd5ccc9561496568a2752afb6"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88ba073cf16d5372720ec942a8ccbf61626074c6d4dd2e745299726ce8b89670"
-
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87f4261229030a858f36b459e748ae97545d6f1ec60e5e0d6a3d32e0dc232ee9"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db3c2bf3d13d5b658be73463284eaf12830ac9a26a90c717b7f771dfe97487bf"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e4246f76bdeff09eb48875a0fd3e2af6aada79d409d33011886d3e1581517d9"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "852298e482cd67c356ddd9570386e2862b5673c85bd5f88df9ab6802b334c596"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.52.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
--- a/build_rust.py
+++ b/build_rust.py
@@ -1,8 +1,10 @@
 # A build script for poetry that adds the rust extension.

+import itertools
 import os
 from typing import Any, Dict

+from packaging.specifiers import SpecifierSet
 from setuptools_rust import Binding, RustExtension


@@ -14,6 +16,8 @@ def build(setup_kwargs: Dict[str, Any]) -> None:
        target="synapse.synapse_rust",
        path=cargo_toml_path,
        binding=Binding.PyO3,
+        # This flag is a no-op in the latest versions. Instead, we need to
+        # specify this in the `bdist_wheel` config below.
        py_limited_api=True,
        # We force always building in release mode, as we can't tell the
        # difference between using `poetry` in development vs production.
@@ -21,3 +25,18 @@ def build(setup_kwargs: Dict[str, Any]) -> None:
    )
    setup_kwargs.setdefault("rust_extensions", []).append(extension)
    setup_kwargs["zip_safe"] = False
+
+    # We lookup the minimum supported python version by looking at
+    # `python_requires` (e.g. ">=3.9.0,<4.0.0") and finding the first python
+    # version that matches. We then convert that into the `py_limited_api` form,
+    # e.g. cp39 for python 3.9.
+    py_limited_api: str
+    python_bounds = SpecifierSet(setup_kwargs["python_requires"])
+    for minor_version in itertools.count(start=8):
+        if f"3.{minor_version}.0" in python_bounds:
+            py_limited_api = f"cp3{minor_version}"
+            break
+
+    setup_kwargs.setdefault("options", {}).setdefault("bdist_wheel", {})[
+        "py_limited_api"
+    ] = py_limited_api
--- a/changelog.d/17749.doc
+++ b/changelog.d/17749.doc
@@ -1 +0,0 @@
-Remove spurious "TODO UPDATE ALL THIS" note in the Debian installation docs.
--- a/contrib/cmdclient/console.py
+++ b/contrib/cmdclient/console.py
@@ -245,7 +245,7 @@ class SynapseCmd(cmd.Cmd):

        if "flows" not in json_res:
            print("Failed to find any login flows.")
-            defer.returnValue(False)
+            return False

        flow = json_res["flows"][0]  # assume first is the one we want.
        if "type" not in flow or "m.login.password" != flow["type"] or "stages" in flow:
@@ -254,8 +254,8 @@ class SynapseCmd(cmd.Cmd):
                "Unable to login via the command line client. Please visit "
                "%s to login." % fallback_url
            )
-            defer.returnValue(False)
-        defer.returnValue(True)
+            return False
+        return True

    def do_emailrequest(self, line):
        """Requests the association of a third party identifier
--- a/contrib/cmdclient/http.py
+++ b/contrib/cmdclient/http.py
@@ -78,7 +78,7 @@ class TwistedHttpClient(HttpClient):
            url, data, headers_dict={"Content-Type": ["application/json"]}
        )
        body = yield readBody(response)
-        defer.returnValue((response.code, body))
+        return response.code, body

    @defer.inlineCallbacks
    def get_json(self, url, args=None):
@@ -88,7 +88,7 @@ class TwistedHttpClient(HttpClient):
            url = "%s?%s" % (url, qs)
        response = yield self._create_get_request(url)
        body = yield readBody(response)
-        defer.returnValue(json.loads(body))
+        return json.loads(body)

    def _create_put_request(self, url, json_data, headers_dict: Optional[dict] = None):
        """Wrapper of _create_request to issue a PUT request"""
@@ -134,7 +134,7 @@ class TwistedHttpClient(HttpClient):
            response = yield self._create_request(method, url)

        body = yield readBody(response)
-        defer.returnValue(json.loads(body))
+        return json.loads(body)

    @defer.inlineCallbacks
    def _create_request(
@@ -173,7 +173,7 @@ class TwistedHttpClient(HttpClient):
        if self.verbose:
            print("Status %s %s" % (response.code, response.phrase))
            print(pformat(list(response.headers.getAllRawHeaders())))
-        defer.returnValue(response)
+        return response

    def sleep(self, seconds):
        d = defer.Deferred()
--- a/contrib/docker/README.md
+++ b/contrib/docker/README.md
@@ -30,3 +30,6 @@ docker-compose up -d
 ### More information

 For more information on required environment variables and mounts, see the main docker documentation at [/docker/README.md](../../docker/README.md)
+
+**For a more comprehensive Docker Compose example showcasing a full Matrix 2.0 stack, please see
+https://github.com/element-hq/element-docker-demo**
--- a/contrib/docker_compose_workers/README.md
+++ b/contrib/docker_compose_workers/README.md
@@ -8,6 +8,9 @@ All examples and snippets assume that your Synapse service is called `synapse` i

 An example Docker Compose file can be found [here](docker-compose.yaml).

+**For a more comprehensive Docker Compose example, showcasing a full Matrix 2.0 stack (originally based on this
+docker-compose.yaml), please see https://github.com/element-hq/element-docker-demo**
+
 ## Worker Service Examples in Docker Compose

 In order to start the Synapse container as a worker, you must specify an `entrypoint` that loads both the `homeserver.yaml` and the configuration for the worker (`synapse-generic-worker-1.yaml` in the example below). You must also include the worker type in the environment variable `SYNAPSE_WORKER` or alternatively pass `-m synapse.app.generic_worker` as part of the `entrypoint` after `"/start.py", "run"`).
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,105 @@
+matrix-synapse-py3 (1.122.0) stable; urgency=medium
+
+  * New Synapse release 1.122.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 14 Jan 2025 14:14:14 +0000
+
+matrix-synapse-py3 (1.122.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.122.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 07 Jan 2025 14:06:19 +0000
+
+matrix-synapse-py3 (1.121.1) stable; urgency=medium
+
+  * New Synapse release 1.121.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 11 Dec 2024 18:24:48 +0000
+
+matrix-synapse-py3 (1.121.0) stable; urgency=medium
+
+  * New Synapse release 1.121.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 11 Dec 2024 13:12:30 +0100
+
+matrix-synapse-py3 (1.121.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.121.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 04 Dec 2024 14:47:23 +0000
+
+matrix-synapse-py3 (1.120.2) stable; urgency=medium
+
+  * New synapse release 1.120.2.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 03 Dec 2024 15:43:37 +0000
+
+matrix-synapse-py3 (1.120.1) stable; urgency=medium
+
+  * New synapse release 1.120.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 03 Dec 2024 09:07:57 +0000
+
+matrix-synapse-py3 (1.120.0) stable; urgency=medium
+
+  * New synapse release 1.120.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 26 Nov 2024 13:10:23 +0000
+
+matrix-synapse-py3 (1.120.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.120.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 20 Nov 2024 15:02:21 +0000
+
+matrix-synapse-py3 (1.119.0) stable; urgency=medium
+
+  * New Synapse release 1.119.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 13 Nov 2024 13:57:51 +0000
+
+matrix-synapse-py3 (1.119.0~rc2) stable; urgency=medium
+
+  * New Synapse release 1.119.0rc2.
+
+ -- Synapse Packaging team <packages@matrix.org>  Mon, 11 Nov 2024 14:33:02 +0000
+
+matrix-synapse-py3 (1.119.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.119.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 06 Nov 2024 08:59:43 -0700
+
+matrix-synapse-py3 (1.118.0) stable; urgency=medium
+
+  * New Synapse release 1.118.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 29 Oct 2024 15:29:53 +0100
+
+matrix-synapse-py3 (1.118.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.118.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 22 Oct 2024 11:48:14 +0100
+
+matrix-synapse-py3 (1.117.0) stable; urgency=medium
+
+  * New Synapse release 1.117.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 15 Oct 2024 10:46:30 +0100
+
+matrix-synapse-py3 (1.117.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.117.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 08 Oct 2024 14:37:11 +0100
+
+matrix-synapse-py3 (1.116.0) stable; urgency=medium
+
+  * New Synapse release 1.116.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 01 Oct 2024 11:14:07 +0100
+
 matrix-synapse-py3 (1.116.0~rc2) stable; urgency=medium

  * New synapse release 1.116.0rc2.
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -20,7 +20,7 @@
 # `poetry export | pip install -r /dev/stdin`, but beware: we have experienced bugs in
 # in `poetry export` in the past.

-ARG PYTHON_VERSION=3.11
+ARG PYTHON_VERSION=3.12

 ###
 ### Stage 0: generate requirements.txt
--- a/docker/complement/conf/workers-shared-extra.yaml.j2
+++ b/docker/complement/conf/workers-shared-extra.yaml.j2
@@ -7,6 +7,7 @@
 #}

 ## Server ##
+public_baseurl: http://127.0.0.1:8008/
 report_stats: False
 trusted_key_servers: []
 enable_registration: true
@@ -104,6 +105,16 @@ experimental_features:
  msc3967_enabled: true
  # Expose a room summary for public rooms
  msc3266_enabled: true
+  # Send to-device messages to application services
+  msc2409_to_device_messages_enabled: true
+  # Allow application services to masquerade devices
+  msc3202_device_masquerading: true
+  # Sending device list changes, one-time key counts and fallback key usage to application services
+  msc3202_transaction_extensions: true
+  # Proxy OTK claim requests to exclusive ASes
+  msc3983_appservice_otk_claims: true
+  # Proxy key queries to exclusive ASes
+  msc3984_appservice_key_query: true

 server_notices:
  system_mxid_localpart: _server
--- a/docker/conf-workers/nginx.conf.j2
+++ b/docker/conf-workers/nginx.conf.j2
@@ -38,10 +38,13 @@ server {
 {% if using_unix_sockets %}
        proxy_pass http://unix:/run/main_public.sock;
 {% else %}
+        # note: do not add a path (even a single /) after the port in `proxy_pass`,
+        # otherwise nginx will canonicalise the URI and cause signature verification
+        # errors.
        proxy_pass http://localhost:8080;
 {% endif %}
        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
-        proxy_set_header Host $host;
+        proxy_set_header Host $host:$server_port;
    }
 }
--- a/docs/SUMMARY.md
+++ b/docs/SUMMARY.md
@@ -54,6 +54,7 @@
      - [Using `synctl` with Workers](synctl_workers.md)
      - [Systemd](systemd-with-workers/README.md)
  - [Administration](usage/administration/README.md)
+    - [Backups](usage/administration/backups.md)
    - [Admin API](usage/administration/admin_api/README.md)
      - [Account Validity](admin_api/account_validity.md)
      - [Background Updates](usage/administration/admin_api/background_updates.md)
--- a/docs/admin_api/event_reports.md
+++ b/docs/admin_api/event_reports.md
@@ -60,10 +60,11 @@ paginate through.
  anything other than the return value of `next_token` from a previous call. Defaults to `0`.
 * `dir`: string - Direction of event report order. Whether to fetch the most recent
  first (`b`) or the oldest first (`f`). Defaults to `b`.
-* `user_id`: string - Is optional and filters to only return users with user IDs that
-  contain this value. This is the user who reported the event and wrote the reason.
-* `room_id`: string - Is optional and filters to only return rooms with room IDs that
-  contain this value.
+* `user_id`: optional string - Filter by the user ID of the reporter. This is the user who reported the event
+   and wrote the reason.
+* `room_id`: optional string - Filter by room id.
+* `event_sender_user_id`: optional string - Filter by the sender of the reported event. This is the user who 
+   the report was made against.

 **Response**

--- a/docs/admin_api/experimental_features.md
+++ b/docs/admin_api/experimental_features.md
@@ -5,6 +5,7 @@ basis. The currently supported features are:
 - [MSC3881](https://github.com/matrix-org/matrix-spec-proposals/pull/3881): enable remotely toggling push notifications
 for another client
 - [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575): enable experimental sliding sync support
+- [MSC4222](https://github.com/matrix-org/matrix-spec-proposals/pull/4222): adding `state_after` to sync v2

 To use it, you will need to authenticate by providing an `access_token`
 for a server admin: see [Admin API](../usage/administration/admin_api/).
--- a/docs/admin_api/user_admin_api.md
+++ b/docs/admin_api/user_admin_api.md
@@ -40,6 +40,7 @@ It returns a JSON body like the following:
    "erased": false,
    "shadow_banned": 0,
    "creation_ts": 1560432506,
+    "last_seen_ts": 1732919539393,
    "appservice_id": null,
    "consent_server_notice_sent": null,
    "consent_version": null,
@@ -55,7 +56,8 @@ It returns a JSON body like the following:
        }
    ],
    "user_type": null,
-    "locked": false
+    "locked": false,
+    "suspended": false
 }
 ```

@@ -476,9 +478,9 @@ with a body of:
 }
 ```

-## List room memberships of a user
+## List joined rooms of a user

-Gets a list of all `room_id` that a specific `user_id` is member.
+Gets a list of all `room_id` that a specific `user_id` is joined to and is a member of (participating in).

 The API is:

@@ -515,6 +517,73 @@ The following fields are returned in the JSON response body:
 - `joined_rooms` - An array of `room_id`.
 - `total` - Number of rooms.

+## Get the number of invites sent by the user
+
+Fetches the number of invites sent by the provided user ID across all rooms
+after the given timestamp.
+
+```
+GET /_synapse/admin/v1/users/$user_id/sent_invite_count
+```
+
+**Parameters**
+
+The following parameters should be set in the URL:
+
+* `user_id`: fully qualified: for example, `@user:server.com`
+
+The following should be set as query parameters in the URL:
+
+* `from_ts`: int, required. A timestamp in ms from the unix epoch. Only
+   invites sent at or after the provided timestamp will be returned.
+   This works by comparing the provided timestamp to the `received_ts`
+   column in the `events` table.
+   Note: https://currentmillis.com/ is a useful tool for converting dates
+   into timestamps and vice versa.
+
+A response body like the following is returned:
+
+```json
+{
+  "invite_count": 30
+}
+```
+
+_Added in Synapse 1.122.0_
+
+## Get the cumulative number of rooms a user has joined after a given timestamp
+
+Fetches the number of rooms that the user joined after the given timestamp, even
+if they have subsequently left/been banned from those rooms.
+
+```
+GET /_synapse/admin/v1/users/$<user_id/cumulative_joined_room_count
+```
+
+**Parameters**
+
+The following parameters should be set in the URL:
+
+* `user_id`: fully qualified: for example, `@user:server.com`
+
+The following should be set as query parameters in the URL:
+
+* `from_ts`: int, required. A timestamp in ms from the unix epoch. Only
+   invites sent at or after the provided timestamp will be returned.
+   This works by comparing the provided timestamp to the `received_ts`
+   column in the `events` table.
+   Note: https://currentmillis.com/ is a useful tool for converting dates
+   into timestamps and vice versa.
+
+A response body like the following is returned:
+
+```json
+{
+  "cumulative_joined_room_count": 30
+}
+```
+_Added in Synapse 1.122.0_
+
 ## Account Data
 Gets information about account data for a specific `user_id`.

@@ -1365,6 +1434,9 @@ _Added in Synapse 1.72.0._

 ## Redact all the events of a user

+This endpoint allows an admin to redact the events of a given user. There are no restrictions on redactions for a 
+local user. By default, we puppet the user who sent the message to redact it themselves. Redactions for non-local users are issued using the admin user, and will fail in rooms where the admin user is not admin/does not have the specified power level to issue redactions. 
+
 The API is 
 ```
 POST /_synapse/admin/v1/user/$user_id/redact
@@ -1440,4 +1512,6 @@ The following fields are returned in the JSON response body:
 - `failed_redactions` - dictionary - the keys of the dict are event ids the process was unable to redact, if any, and the values are 
  the corresponding error that caused the redaction to fail

-_Added in Synapse 1.116.0._
+_Added in Synapse 1.116.0._
+
+
--- a/docs/changelogs/CHANGES-2023.md
+++ b/docs/changelogs/CHANGES-2023.md
--- a/docs/changelogs/CHANGES-2024.md
+++ b/docs/changelogs/CHANGES-2024.md
--- a/docs/development/contributing_guide.md
+++ b/docs/development/contributing_guide.md
@@ -322,7 +322,7 @@ The following command will let you run the integration test with the most common
 configuration:

 ```sh
-$ docker run --rm -it -v /path/where/you/have/cloned/the/repository\:/src:ro -v /path/to/where/you/want/logs\:/logs matrixdotorg/sytest-synapse:focal
+$ docker run --rm -it -v /path/where/you/have/cloned/the/repository\:/src:ro -v /path/to/where/you/want/logs\:/logs matrixdotorg/sytest-synapse:bullseye
 ```
 (Note that the paths must be full paths! You could also write `$(realpath relative/path)` if needed.)

--- a/docs/modules/spam_checker_callbacks.md
+++ b/docs/modules/spam_checker_callbacks.md
@@ -76,8 +76,9 @@ _Changed in Synapse v1.62.0: `synapse.module_api.NOT_SPAM` and `synapse.module_a
 async def user_may_invite(inviter: str, invitee: str, room_id: str) -> Union["synapse.module_api.NOT_SPAM", "synapse.module_api.errors.Codes", bool]
 ```

-Called when processing an invitation. Both inviter and invitee are
-represented by their Matrix user ID (e.g. `@alice:example.com`).
+Called when processing an invitation, both when one is created locally or when
+receiving an invite over federation. Both inviter and invitee are represented by
+their Matrix user ID (e.g. `@alice:example.com`).


 The callback must return one of:
@@ -112,7 +113,9 @@ async def user_may_send_3pid_invite(
 ```

 Called when processing an invitation using a third-party identifier (also called a 3PID,
-e.g. an email address or a phone number). 
+e.g. an email address or a phone number). It is only called when a 3PID invite is created
+locally - not when one is received in a room over federation. If the 3PID is already associated
+with a Matrix ID, the spam check will go through the `user_may_invite` callback instead.

 The inviter is represented by their Matrix user ID (e.g. `@alice:example.com`), and the
 invitee is represented by its medium (e.g. "email") and its address
@@ -242,7 +245,7 @@ this callback.
 _First introduced in Synapse v1.37.0_

 ```python
-async def check_username_for_spam(user_profile: synapse.module_api.UserProfile) -> bool
+async def check_username_for_spam(user_profile: synapse.module_api.UserProfile, requester_id: str) -> bool
 ```

 Called when computing search results in the user directory. The module must return a
@@ -261,6 +264,8 @@ The profile is represented as a dictionary with the following keys:
 The module is given a copy of the original dictionary, so modifying it from within the
 module cannot modify a user's profile when included in user directory search results.

+The requester_id parameter is the ID of the user that called the user directory API.
+
 If multiple modules implement this callback, they will be considered in order. If a
 callback returns `False`, Synapse falls through to the next one. The value of the first
 callback that does not return `False` will be used. If this happens, Synapse will not call
--- a/docs/openid.md
+++ b/docs/openid.md
@@ -336,6 +336,36 @@ but it has a `response_types_supported` which excludes "code" (which we rely on,
 is even mentioned in their [documentation](https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow#login)),
 so we have to disable discovery and configure the URIs manually.

+### Forgejo
+
+Forgejo is a fork of Gitea that can act as an OAuth2 provider.
+
+The implementation of OAuth2 is improved compared to Gitea, as it provides a correctly defined `subject_claim` and `scopes`.
+
+Synapse config:
+
+```yaml
+oidc_providers:
+  - idp_id: forgejo
+    idp_name: Forgejo
+    discover: false
+    issuer: "https://your-forgejo.com/"
+    client_id: "your-client-id" # TO BE FILLED
+    client_secret: "your-client-secret" # TO BE FILLED
+    client_auth_method: client_secret_post
+    scopes: ["openid", "profile", "email", "groups"]
+    authorization_endpoint: "https://your-forgejo.com/login/oauth/authorize"
+    token_endpoint: "https://your-forgejo.com/login/oauth/access_token"
+    userinfo_endpoint: "https://your-forgejo.com/api/v1/user"
+    user_mapping_provider:
+      config:
+        subject_claim: "sub"
+        picture_claim: "picture"
+        localpart_template: "{{ user.preferred_username }}"
+        display_name_template: "{{ user.name }}"
+        email_template: "{{ user.email }}"
+```
+
 ### GitHub

 [GitHub][github-idp] is a bit special as it is not an OpenID Connect compliant provider, but
--- a/docs/postgres.md
+++ b/docs/postgres.md
@@ -100,6 +100,10 @@ database:
    keepalives_count: 3
 ```

+## Backups
+
+Don't forget to [back up](./usage/administration/backups.md#database) your database!
+
 ## Tuning Postgres

 The default settings should be fine for most deployments. For larger
--- a/docs/reverse_proxy.md
+++ b/docs/reverse_proxy.md
@@ -74,7 +74,7 @@ server {
        proxy_pass http://localhost:8008;
        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
-        proxy_set_header Host $host;
+        proxy_set_header Host $host:$server_port;

        # Nginx by default only allows file uploads up to 1M in size
        # Increase client_max_body_size to match max_upload_size defined in homeserver.yaml
--- a/docs/setup/installation.md
+++ b/docs/setup/installation.md
@@ -157,7 +157,7 @@ sudo pip install py-bcrypt

 #### Alpine Linux

-6543 maintains [Synapse packages for Alpine Linux](https://pkgs.alpinelinux.org/packages?name=synapse&branch=edge) in the community repository. Install with:
+Jahway603 maintains [Synapse packages for Alpine Linux](https://pkgs.alpinelinux.org/packages?name=synapse&branch=edge) in the community repository. Install with:

 ```sh
 sudo apk add synapse
@@ -208,7 +208,7 @@ When following this route please make sure that the [Platform-specific prerequis
 System requirements:

 - POSIX-compliant system (tested on Linux & OS X)
- Python 3.8 or later, up to Python 3.11.
+- Python 3.9 or later, up to Python 3.13.
 - At least 1GB of free RAM if you want to join large public rooms like #matrix:matrix.org

 If building on an uncommon architecture for which pre-built wheels are
@@ -656,6 +656,10 @@ This also requires the optional `lxml` python dependency to be  installed. This
 in turn requires the `libxml2` library to be available - on  Debian/Ubuntu this
 means `apt-get install libxml2-dev`, or equivalent for your OS.

+### Backups
+
+Don't forget to take [backups](../usage/administration/backups.md) of your new server!
+
 ### Troubleshooting Installation

 `pip` seems to leak *lots* of memory during installation. For instance, a Linux
--- a/docs/spam_checker.md
+++ b/docs/spam_checker.md
@@ -72,8 +72,8 @@ class ExampleSpamChecker:
    async def user_may_publish_room(self, userid, room_id):
        return True  # allow publishing of all rooms

-    async def check_username_for_spam(self, user_profile):
-        return False  # allow all usernames
+    async def check_username_for_spam(self, user_profile, requester_id):
+        return False  # allow all usernames regardless of requester

    async def check_registration_for_spam(
        self,
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -117,6 +117,59 @@ each upgrade are complete before moving on to the next upgrade, to avoid
 stacking them up. You can monitor the currently running background updates with
 [the Admin API](usage/administration/admin_api/background_updates.html#status).

+# Upgrading to v1.122.0
+
+## Dropping support for PostgreSQL 11 and 12
+
+In line with our [deprecation policy](deprecation_policy.md), we've dropped
+support for PostgreSQL 11 and 12, as they are no longer supported upstream.
+This release of Synapse requires PostgreSQL 13+.
+
+# Upgrading to v1.120.0
+
+## Removal of experimental MSC3886 feature
+
+[MSC3886](https://github.com/matrix-org/matrix-spec-proposals/pull/3886)
+has been closed (and will not enter the Matrix spec). As such, we are
+removing the experimental support for it in this release.
+
+The `experimental_features.msc3886_endpoint` configuration option has
+been removed.
+
+## Authenticated media is now enforced by default
+
+The [`enable_authenticated_media`] configuration option now defaults to true.
+
+This means that clients and remote (federated) homeservers now need to use
+the authenticated media endpoints in order to download media from your
+homeserver.
+
+As an exception, existing media that was stored on the server prior to
+this option changing to `true` will still be accessible over the
+unauthenticated endpoints.
+
+The matrix.org homeserver has already been running with this option enabled
+since September 2024, so most common clients and homeservers should already
+be compatible.
+
+With that said, administrators who wish to disable this feature for broader
+compatibility can still do so by manually configuring
+`enable_authenticated_media: False`.
+
+[`enable_authenticated_media`]: usage/configuration/config_documentation.md#enable_authenticated_media
+
+
+# Upgrading to v1.119.0
+
+## Minimum supported Python version
+
+The minimum supported Python version has been increased from v3.8 to v3.9.
+You will need Python 3.9+ to run Synapse v1.119.0 (due out Nov 7th, 2024).
+
+If you use current versions of the Matrix.org-distributed Docker images, no action is required.
+Please note that support for Ubuntu `focal` was dropped as well since it uses Python 3.8.
+
+
 # Upgrading to v1.111.0

 ## New worker endpoints for authenticated client and federation media
--- a/docs/usage/administration/admin_faq.md
+++ b/docs/usage/administration/admin_faq.md
@@ -255,6 +255,8 @@ line to `/etc/default/matrix-synapse`:

    LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2

+*Note*: You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches-and-associated-values) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process.
+
 This made a significant difference on Python 2.7 - it's unclear how
 much of an improvement it provides on Python 3.x.

--- a/docs/usage/administration/backups.md
+++ b/docs/usage/administration/backups.md
@@ -0,0 +1,125 @@
+# How to back up a Synapse homeserver
+
+It is critical to maintain good backups of your server, to guard against
+hardware failure as well as potential corruption due to bugs or administrator
+error.
+
+This page documents the things you will need to consider backing up as part of
+a Synapse installation.
+
+## Configuration files
+
+Keep a copy of your configuration file (`homeserver.yaml`), as well as any
+auxiliary config files it refers to such as the
+[`log_config`](../configuration/config_documentation.md#log_config) file,
+[`app_service_config_files`](../configuration/config_documentation.md#app_service_config_files).
+Often, all such config files will be kept in a single directory such as
+`/etc/synapse`, which will make this easier.
+
+## Server signing key
+
+Your server has a [signing
+key](../configuration/config_documentation.md#signing_key_path) which it uses
+to sign events and outgoing federation requests. It is easiest to back it up
+with your configuration files, but an alternative is to have Synapse create a
+new signing key if you have to restore.
+
+If you do decide to replace the signing key, you should add the old *public*
+key to
+[`old_signing_keys`](../configuration/config_documentation.md#old_signing_keys).
+
+## Database
+
+Synapse's support for SQLite is only suitable for testing purposes, so for the
+purposes of this document, we'll assume you are using
+[PostgreSQL](../../postgres.md).
+
+A full discussion of backup strategies for PostgreSQL is out of scope for this
+document; see the [PostgreSQL
+documentation](https://www.postgresql.org/docs/current/backup.html) for
+detailed information.
+
+### Synapse-specfic details
+
+ * Be very careful not to restore into a database that already has tables
+   present. At best, this will error; at worst, it will lead to subtle database
+   inconsistencies.
+
+ * The `e2e_one_time_keys_json` table should **not** be backed up, or if it is
+   backed up, should be
+   [`TRUNCATE`d](https://www.postgresql.org/docs/current/sql-truncate.html)
+   after restoring the database before Synapse is started.
+
+   [Background: restoring the database to an older backup can cause
+   used one-time-keys to be re-issued, causing subsequent [message decryption
+   errors](https://github.com/element-hq/element-meta/issues/2155). Clearing
+   all one-time-keys from the database ensures that this cannot happen, and
+   will prompt clients to generate and upload new one-time-keys.]
+
+### Quick and easy database backup and restore
+
+Typically, the easiest solution is to use `pg_dump` to take a copy of the whole
+database. We recommend `pg_dump`'s custom dump format, as it produces
+significantly smaller backup files.
+
+```shell
+sudo -u postgres pg_dump -Fc --exclude-table-data e2e_one_time_keys_json synapse > synapse.dump
+```
+
+There is no need to stop Postgres or Synapse while `pg_dump` is running: it
+will take a consistent snapshot of the databse.
+
+To restore, you will need to recreate the database as described in [Using
+Postgres](../../postgres.md#set-up-database),
+then load the dump into it with `pg_restore`:
+
+```shell
+sudo -u postgres createdb --encoding=UTF8 --locale=C --template=template0 --owner=synapse_user synapse
+sudo -u postgres pg_restore -d synapse < synapse.dump
+```
+
+(If you forgot to exclude `e2e_one_time_keys_json` during `pg_dump`, remember
+to connect to the new database and `TRUNCATE e2e_one_time_keys_json;` before
+starting Synapse.)
+
+To reiterate: do **not** restore a dump over an existing database.
+
+Again, if you plan to run your homeserver at any sort of production level, we
+recommend studying the PostgreSQL documentation on backup options.
+
+## Media store
+
+Synapse keeps a copy of media uploaded by users, including avatars and message
+attachments, in its [Media
+store](../configuration/config_documentation.md#media-store).
+
+It is a directory on the local disk, containing the following directories:
+
+ * `local_content`: this is content uploaded by your local users. As a general
+   rule, you should back this up: it may represent the only copy of those
+   media files anywhere in the federation, and if they are lost, users will
+   see errors when viewing user or room avatars, and messages with attachments.
+
+ * `local_thumbnails`: "thumbnails" of images uploaded by your users. If
+   [`dynamic_thumbnails`](../configuration/config_documentation.md#dynamic_thumbnails)
+   is enabled, these will be regenerated if they are removed from the disk, and
+   there is therefore no need to back them up.
+
+   If `dynamic_thumbnails` is *not* enabled (the default): although this can
+   theoretically be regenerated from `local_content`, there is no tooling to do
+   so. We recommend that these are backed up too.
+
+ * `remote_content`: this is a cache of content that was uploaded by a user on
+    another server, and has since been requested by a user on your own server.
+
+    Typically there is no need to back up this directory: if a file in this directory
+    is removed, Synapse will attempt to fetch it again from the remote
+    server.
+
+ * `remote_thumbnails`: thumbnails of images uploaded by users on other
+    servers. As with `remote_content`, there is normally no need to back this
+    up.
+
+ * `url_cache`, `url_cache_thumbnails`: temporary caches of files downloaded
+   by the [URL previews](../../setup/installation.md#url-previews) feature.
+   These do not need to be backed up.
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -673,8 +673,9 @@ This setting has the following sub-options:
   TLS via STARTTLS *if the SMTP server supports it*. If this option is set,
   Synapse will refuse to connect unless the server supports STARTTLS.
 * `enable_tls`: By default, if the server supports TLS, it will be used, and the server
-   must present a certificate that is valid for 'smtp_host'. If this option
+   must present a certificate that is valid for `tlsname`. If this option
   is set to false, TLS will not be used.
+* `tlsname`: The domain name the SMTP server's TLS certificate must be valid for, defaulting to `smtp_host`.
 * `notif_from`: defines the "From" address to use when sending emails.
    It must be set if email sending is enabled. The placeholder '%(app)s' will be replaced by the application name,
    which is normally set in `app_name`, but may be overridden by the
@@ -741,6 +742,7 @@ email:
  force_tls: true
  require_transport_security: true
  enable_tls: false
+  tlsname: mail.server.example.com
  notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
  app_name: my_branded_matrix_server
  enable_notifs: true
@@ -1434,7 +1436,7 @@ number of entries that can be stored.
   Please see the [Config Conventions](#config-conventions) for information on how to specify memory size and cache expiry
   durations.
     * `max_cache_memory_usage` sets a ceiling on how much memory the cache can use before caches begin to be continuously evicted.
-        They will continue to be evicted until the memory usage drops below the `target_memory_usage`, set in
+        They will continue to be evicted until the memory usage drops below the `target_cache_memory_usage`, set in
        the setting below, or until the `min_cache_ttl` is hit. There is no default value for this option.
     * `target_cache_memory_usage` sets a rough target for the desired memory usage of the caches. There is no default value
        for this option.
@@ -1887,12 +1889,33 @@ Config options related to Synapse's media store.

 When set to true, all subsequent media uploads will be marked as authenticated, and will not be available over legacy
 unauthenticated media endpoints (`/_matrix/media/(r0|v3|v1)/download` and `/_matrix/media/(r0|v3|v1)/thumbnail`) - requests for authenticated media over these endpoints will result in a 404. All media, including authenticated media, will be available over the authenticated media endpoints `_matrix/client/v1/media/download` and `_matrix/client/v1/media/thumbnail`. Media uploaded prior to setting this option to true will still be available over the legacy endpoints. Note if the setting is switched to false
-after enabling, media marked as authenticated will be available over legacy endpoints. Defaults to false, but
-this will change to true in a future Synapse release.
+after enabling, media marked as authenticated will be available over legacy endpoints. Defaults to true (previously false). In a future release of Synapse, this option will be removed and become always-on.
+
+In all cases, authenticated requests to download media will succeed, but for unauthenticated requests, this
+case-by-case breakdown describes whether media downloads are permitted:
+
+* `enable_authenticated_media = False`:
+  * unauthenticated client or homeserver requesting local media: allowed
+  * unauthenticated client or homeserver requesting remote media: allowed as long as the media is in the cache,
+    or as long as the remote homeserver does not require authentication to retrieve the media
+* `enable_authenticated_media = True`:
+  * unauthenticated client or homeserver requesting local media:
+    allowed if the media was stored on the server whilst `enable_authenticated_media` was `False` (or in a previous Synapse version where this option did not exist);
+    otherwise denied.
+  * unauthenticated client or homeserver requesting remote media: the same as for local media;
+    allowed if the media was stored on the server whilst `enable_authenticated_media` was `False` (or in a previous Synapse version where this option did not exist);
+    otherwise denied.
+
+It is especially notable that media downloaded before this option existed (in older Synapse versions), or whilst this option was set to `False`,
+will perpetually be available over the legacy, unauthenticated endpoint, even after this option is set to `True`.
+This is for backwards compatibility with older clients and homeservers that do not yet support requesting authenticated media;
+those older clients or homeservers will not be cut off from media they can already see.
+
+_Changed in Synapse 1.120:_ This option now defaults to `True` when not set, whereas before this version it defaulted to `False`.

 Example configuration:
 ```yaml
-enable_authenticated_media: true
+enable_authenticated_media: false
 ```
 ---
 ### `enable_media_repo`
@@ -3070,6 +3093,22 @@ Example configuration:
 ```yaml
 macaroon_secret_key: <PRIVATE STRING>
 ```
+---
+### `macaroon_secret_key_path`
+
+An alternative to [`macaroon_secret_key`](#macaroon_secret_key):
+allows the secret key to be specified in an external file.
+
+The file should be a plain text file, containing only the secret key.
+Synapse reads the secret key from the given file once at startup.
+
+Example configuration:
+```yaml
+macaroon_secret_key_path: /path/to/secrets/file
+```
+
+_Added in Synapse 1.121.0._
+
 ---
 ### `form_secret`

@@ -3108,6 +3147,15 @@ it was last used.
 It is possible to build an entry from an old `signing.key` file using the
 `export_signing_key` script which is provided with synapse.

+If you have lost the private key file, you can ask another server you trust to
+tell you the public keys it has seen from your server. To fetch the keys from
+`matrix.org`, try something like:
+
+```
+curl https://matrix-federation.matrix.org/_matrix/key/v2/query/myserver.example.com |
+  jq '.server_keys | map(.verify_keys) | add'
+```
+
 Example configuration:
 ```yaml
 old_signing_keys:
@@ -3722,6 +3770,8 @@ Additional sub-options for this setting include:
   Required if `enabled` is set to true.
 * `subject_claim`: Name of the claim containing a unique identifier for the user.
   Optional, defaults to `sub`.
+* `display_name_claim`: Name of the claim containing the display name for the user. Optional.
+   If provided, the display name will be set to the value of this claim upon first login.
 * `issuer`: The issuer to validate the "iss" claim against. Optional. If provided the
   "iss" claim will be required and validated for all JSON web tokens.
 * `audiences`: A list of audiences to validate the "aud" claim against. Optional.
@@ -3736,6 +3786,7 @@ jwt_config:
    secret: "provided-by-your-issuer"
    algorithm: "provided-by-your-issuer"
    subject_claim: "name_of_claim"
+    display_name_claim: "name_of_claim"
    issuer: "provided-by-your-issuer"
    audiences:
        - "provided-by-your-issuer"
@@ -4370,6 +4421,12 @@ a `federation_sender_instances` map. Doing so will remove handling of this funct
 the main process. Multiple workers can be added to this map, in which case the work is
 balanced across them.

+The way that the load balancing works is any outbound federation request will be assigned
+to a federation sender worker based on the hash of the destination server name. This
+means that all requests being sent to the same destination will be processed by the same
+worker instance. Multiple `federation_sender_instances` are useful if there is a federation
+with multiple servers.
+
 This configuration setting must be shared between all workers handling federation
 sending, and if changed all federation sender workers must be stopped at the same time
 and then started, to ensure that all instances are running with the same config (otherwise
@@ -4518,6 +4575,9 @@ This setting has the following sub-options:
 * `path`: The full path to a local Unix socket file. **If this is used, `host` and
 `port` are ignored.** Defaults to `/tmp/redis.sock'
 * `password`: Optional password if configured on the Redis instance.
+* `password_path`: Alternative to `password`, reading the password from an
+   external file. The file should be a plain text file, containing only the
+   password. Synapse reads the password from the given file once at startup.
 * `dbid`: Optional redis dbid if needs to connect to specific redis logical db.
 * `use_tls`: Whether to use tls connection. Defaults to false.
 * `certificate_file`: Optional path to the certificate file
@@ -4531,13 +4591,16 @@ This setting has the following sub-options:

  _Changed in Synapse 1.85.0: Added path option to use a local Unix socket_

+  _Changed in Synapse 1.116.0: Added password\_path_
+
 Example configuration:
 ```yaml
 redis:
  enabled: true
  host: localhost
  port: 6379
-  password: <secret_password>
+  password_path: <path_to_the_password_file>
+  # OR password: <secret_password>
  dbid: <dbid>
  #use_tls: True
  #certificate_file: <path_to_the_certificate_file>
@@ -4715,7 +4778,7 @@ This setting has the following sub-options:
 * `only_for_direct_messages`: Whether invites should be automatically accepted for all room types, or only
   for direct messages. Defaults to false.
 * `only_from_local_users`: Whether to only automatically accept invites from users on this homeserver. Defaults to false.
-* `worker_to_run_on`: Which worker to run this module on. This must match 
+* `worker_to_run_on`: Which worker to run this module on. This must match
  the "worker_name". If not set or `null`, invites will be accepted on the
  main process.

--- a/docs/workers.md
+++ b/docs/workers.md
@@ -177,11 +177,11 @@ The following applies to Synapse installations that have been installed from sou

 You can start the main Synapse process with Poetry by running the following command:
 ```console
-poetry run synapse_homeserver --config-file [your homeserver.yaml]
+poetry run synapse_homeserver --config-path [your homeserver.yaml]
 ```
 For worker setups, you can run the following command
 ```console
-poetry run synapse_worker --config-file [your homeserver.yaml] --config-file [your worker.yaml]
+poetry run synapse_worker --config-path [your homeserver.yaml] --config-path [your worker.yaml]
 ```
 ## Available worker applications

@@ -273,17 +273,6 @@ information.
    ^/_matrix/client/(api/v1|r0|v3|unstable)/knock/
    ^/_matrix/client/(api/v1|r0|v3|unstable)/profile/

-    # Account data requests
-    ^/_matrix/client/(r0|v3|unstable)/.*/tags
-    ^/_matrix/client/(r0|v3|unstable)/.*/account_data
-
-    # Receipts requests
-    ^/_matrix/client/(r0|v3|unstable)/rooms/.*/receipt
-    ^/_matrix/client/(r0|v3|unstable)/rooms/.*/read_markers
-
-    # Presence requests
-    ^/_matrix/client/(api/v1|r0|v3|unstable)/presence/
-
    # User directory search requests
    ^/_matrix/client/(r0|v3|unstable)/user_directory/search$

@@ -292,6 +281,13 @@ Additionally, the following REST endpoints can be handled for GET requests:
    ^/_matrix/client/(api/v1|r0|v3|unstable)/pushrules/
    ^/_matrix/client/unstable/org.matrix.msc4140/delayed_events

+    # Account data requests
+    ^/_matrix/client/(r0|v3|unstable)/.*/tags
+    ^/_matrix/client/(r0|v3|unstable)/.*/account_data
+
+    # Presence requests
+    ^/_matrix/client/(api/v1|r0|v3|unstable)/presence/
+
 Pagination requests can also be handled, but all requests for a given
 room must be routed to the same instance. Additionally, care must be taken to
 ensure that the purge history admin API is not used while pagination requests
--- a/flake.lock
+++ b/flake.lock
@@ -56,24 +56,6 @@
        "type": "github"
      }
    },
-    "flake-utils_2": {
-      "inputs": {
-        "systems": "systems_2"
-      },
-      "locked": {
-        "lastModified": 1681202837,
-        "narHash": "sha256-H+Rh19JDwRtpVPAWp64F+rlEtxUWBAQW28eAi3SRSzg=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "cfacdce06f30d2b68473a46042957675eebb3401",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
    "gitignore": {
      "inputs": {
        "nixpkgs": [
@@ -186,27 +168,27 @@
    },
    "nixpkgs_2": {
      "locked": {
-        "lastModified": 1690535733,
-        "narHash": "sha256-WgjUPscQOw3cB8yySDGlyzo6cZNihnRzUwE9kadv/5I=",
+        "lastModified": 1729265718,
+        "narHash": "sha256-4HQI+6LsO3kpWTYuVGIzhJs1cetFcwT7quWCk/6rqeo=",
        "owner": "NixOS",
        "repo": "nixpkgs",
-        "rev": "8cacc05fbfffeaab910e8c2c9e2a7c6b32ce881a",
+        "rev": "ccc0c2126893dd20963580b6478d1a10a4512185",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
-        "ref": "master",
+        "ref": "nixpkgs-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "nixpkgs_3": {
      "locked": {
-        "lastModified": 1681358109,
-        "narHash": "sha256-eKyxW4OohHQx9Urxi7TQlFBTDWII+F+x2hklDOQPB50=",
+        "lastModified": 1728538411,
+        "narHash": "sha256-f0SBJz1eZ2yOuKUr5CA9BHULGXVSn6miBuUWdTyhUhU=",
        "owner": "NixOS",
        "repo": "nixpkgs",
-        "rev": "96ba1c52e54e74c3197f4d43026b3f3d92e83ff9",
+        "rev": "b69de56fac8c2b6f8fd27f2eca01dcda8e0a4221",
        "type": "github"
      },
      "original": {
@@ -249,20 +231,19 @@
        "devenv": "devenv",
        "nixpkgs": "nixpkgs_2",
        "rust-overlay": "rust-overlay",
-        "systems": "systems_3"
+        "systems": "systems_2"
      }
    },
    "rust-overlay": {
      "inputs": {
-        "flake-utils": "flake-utils_2",
        "nixpkgs": "nixpkgs_3"
      },
      "locked": {
-        "lastModified": 1693966243,
-        "narHash": "sha256-a2CA1aMIPE67JWSVIGoGtD3EGlFdK9+OlJQs0FOWCKY=",
+        "lastModified": 1731897198,
+        "narHash": "sha256-Ou7vLETSKwmE/HRQz4cImXXJBr/k9gp4J4z/PF8LzTE=",
        "owner": "oxalica",
        "repo": "rust-overlay",
-        "rev": "a8b4bb4cbb744baaabc3e69099f352f99164e2c1",
+        "rev": "0be641045af6d8666c11c2c40e45ffc9667839b5",
        "type": "github"
      },
      "original": {
@@ -300,21 +281,6 @@
        "repo": "default",
        "type": "github"
      }
-    },
-    "systems_3": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
    }
  },
  "root": "root",
--- a/flake.nix
+++ b/flake.nix
@@ -3,13 +3,13 @@
 # (https://github.com/matrix-org/complement) Matrix homeserver test suites are also
 # installed automatically.
 #
-# You must have already installed Nix (https://nixos.org) on your system to use this.
-# Nix can be installed on Linux or MacOS; NixOS is not required. Windows is not
-# directly supported, but Nix can be installed inside of WSL2 or even Docker
+# You must have already installed Nix (https://nixos.org/download/) on your system to use this.
+# Nix can be installed on any Linux distribiution or MacOS; NixOS is not required.
+# Windows is not directly supported, but Nix can be installed inside of WSL2 or even Docker
 # containers. Please refer to https://nixos.org/download for details.
 #
 # You must also enable support for flakes in Nix. See the following for how to
-# do so permanently: https://nixos.wiki/wiki/Flakes#Enable_flakes
+# do so permanently: https://wiki.nixos.org/wiki/Flakes#Other_Distros,_without_Home-Manager
 #
 # Be warned: you'll need over 3.75 GB of free space to download all the dependencies.
 #
@@ -20,7 +20,7 @@
 # locally from "services", such as PostgreSQL and Redis.
 #
 # You should now be dropped into a new shell with all programs and dependencies
-# availabile to you!
+# available to you!
 #
 # You can start up pre-configured local Synapse, PostgreSQL and Redis instances by
 # running: `devenv up`. To stop them, use Ctrl-C.
@@ -39,9 +39,9 @@

 {
  inputs = {
-    # Use the master/unstable branch of nixpkgs. Used to fetch the latest
+    # Use the rolling/unstable branch of nixpkgs. Used to fetch the latest
    # available versions of packages.
-    nixpkgs.url = "github:NixOS/nixpkgs/master";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    # Output a development shell for x86_64/aarch64 Linux/Darwin (MacOS).
    systems.url = "github:nix-systems/default";
    # A development environment manager built on Nix. See https://devenv.sh.
@@ -50,7 +50,7 @@
    rust-overlay.url = "github:oxalica/rust-overlay";
  };

-  outputs = { self, nixpkgs, devenv, systems, rust-overlay, ... } @ inputs:
+  outputs = { nixpkgs, devenv, systems, rust-overlay, ... } @ inputs:
    let
      forEachSystem = nixpkgs.lib.genAttrs (import systems);
    in {
@@ -82,7 +82,7 @@
                  #
                  # NOTE: We currently need to set the Rust version unnecessarily high
                  # in order to work around https://github.com/matrix-org/synapse/issues/15939
-                  (rust-bin.stable."1.71.1".default.override {
+                  (rust-bin.stable."1.82.0".default.override {
                    # Additionally install the "rust-src" extension to allow diving into the
                    # Rust source code in an IDE (rust-analyzer will also make use of it).
                    extensions = [ "rust-src" ];
@@ -126,7 +126,7 @@
                # Automatically activate the poetry virtualenv upon entering the shell.
                languages.python.poetry.activate.enable = true;
                # Install all extra Python dependencies; this is needed to run the unit
-                # tests and utilitise all Synapse features.
+                # tests and utilise all Synapse features.
                languages.python.poetry.install.arguments = ["--extras all"];
                # Install the 'matrix-synapse' package from the local checkout.
                languages.python.poetry.install.installRootPackage = true;
@@ -163,8 +163,8 @@
                # Create a postgres user called 'synapse_user' which has ownership
                # over the 'synapse' database.
                services.postgres.initialScript = ''
-                CREATE USER synapse_user;
-                ALTER DATABASE synapse OWNER TO synapse_user;
+                  CREATE USER synapse_user;
+                  ALTER DATABASE synapse OWNER TO synapse_user;
                '';

                # Redis is needed in order to run Synapse in worker mode.
@@ -205,7 +205,7 @@
                # corresponding Nix packages on https://search.nixos.org/packages.
                #
                # This was done until `./install-deps.pl --dryrun` produced no output.
-                env.PERL5LIB = "${with pkgs.perl536Packages; makePerlPath [
+                env.PERL5LIB = "${with pkgs.perl538Packages; makePerlPath [
                  DBI
                  ClassMethodModifiers
                  CryptEd25519
--- a/mypy.ini
+++ b/mypy.ini
@@ -26,7 +26,7 @@ strict_equality = True

 # Run mypy type checking with the minimum supported Python version to catch new usage
 # that isn't backwards-compatible (types, overloads, etc).
-python_version = 3.8
+python_version = 3.9

 files =
  docker/,
--- a/poetry.lock
+++ b/poetry.lock
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,7 +36,7 @@

 [tool.ruff]
 line-length = 88
-target-version = "py38"
+target-version = "py39"

 [tool.ruff.lint]
 # See https://beta.ruff.rs/docs/rules/#error-e
@@ -97,7 +97,7 @@ module-name = "synapse.synapse_rust"

 [tool.poetry]
 name = "matrix-synapse"
-version = "1.116.0rc2"
+version = "1.122.0"
 description = "Homeserver for the Matrix decentralised comms protocol"
 authors = ["Matrix.org Team and Contributors <packages@matrix.org>"]
 license = "AGPL-3.0-or-later"
@@ -155,7 +155,7 @@ synapse_review_recent_signups = "synapse._scripts.review_recent_signups:main"
 update_synapse_database = "synapse._scripts.update_synapse_database:main"

 [tool.poetry.dependencies]
-python = "^3.8.0"
+python = "^3.9.0"

 # Mandatory Dependencies
 # ----------------------
@@ -178,7 +178,7 @@ Twisted = {extras = ["tls"], version = ">=18.9.0"}
 treq = ">=15.1"
 # Twisted has required pyopenssl 16.0 since about Twisted 16.6.
 pyOpenSSL = ">=16.0.0"
-PyYAML = ">=3.13"
+PyYAML = ">=5.3"
 pyasn1 = ">=0.1.9"
 pyasn1-modules = ">=0.0.7"
 bcrypt = ">=3.1.7"
@@ -241,7 +241,7 @@ authlib = { version = ">=0.15.1", optional = true }
 # `contrib/systemd/log_config.yaml`.
 # Note: systemd-python 231 appears to have been yanked from pypi
 systemd-python = { version = ">=231", optional = true }
-lxml = { version = ">=4.2.0", optional = true }
+lxml = { version = ">=4.5.2", optional = true }
 sentry-sdk = { version = ">=0.7.2", optional = true }
 opentracing = { version = ">=2.2.0", optional = true }
 jaeger-client = { version = ">=4.0.0", optional = true }
@@ -320,7 +320,7 @@ all = [
 # failing on new releases. Keeping lower bounds loose here means that dependabot
 # can bump versions without having to update the content-hash in the lockfile.
 # This helps prevents merge conflicts when running a batch of dependabot updates.
-ruff = "0.6.7"
+ruff = "0.7.3"
 # Type checking only works with the pydantic.v1 compat module from pydantic v2
 pydantic = "^2"

@@ -370,7 +370,7 @@ tomli = ">=1.2.3"
 # runtime errors caused by build system changes.
 # We are happy to raise these upper bounds upon request,
 # provided we check that it's safe to do so (i.e. that CI passes).
-requires = ["poetry-core>=1.1.0,<=1.9.0", "setuptools_rust>=1.3,<=1.8.1"]
+requires = ["poetry-core>=1.1.0,<=1.9.1", "setuptools_rust>=1.3,<=1.10.2"]
 build-backend = "poetry.core.masonry.api"


@@ -378,16 +378,19 @@ build-backend = "poetry.core.masonry.api"
 # Skip unsupported platforms (by us or by Rust).
 # See https://cibuildwheel.readthedocs.io/en/stable/options/#build-skip for the list of build targets.
 # We skip:
-#  - CPython 3.6 and 3.7: EOLed
-#  - PyPy 3.7: we only support Python 3.8+
+#  - CPython 3.6, 3.7 and 3.8: EOLed
+#  - PyPy 3.7 and 3.8: we only support Python 3.9+
 #  - musllinux i686: excluded to reduce number of wheels we build.
 #    c.f. https://github.com/matrix-org/synapse/pull/12595#discussion_r963107677
 #  - PyPy on Aarch64 and musllinux on aarch64: too slow to build.
 #    c.f. https://github.com/matrix-org/synapse/pull/14259
-skip = "cp36* cp37* pp37* *-musllinux_i686 pp*aarch64 *-musllinux_aarch64"
+skip = "cp36* cp37* cp38* pp37* pp38* *-musllinux_i686 pp*aarch64 *-musllinux_aarch64"

-# We need a rust compiler
-before-all =  "curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain stable -y --profile minimal"
+# We need a rust compiler.
+#
+# We temporarily pin Rust to 1.82.0 to work around
+# https://github.com/element-hq/synapse/issues/17988
+before-all =  "curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain 1.82.0 -y --profile minimal"
 environment= { PATH = "$PATH:$HOME/.cargo/bin" }

 # For some reason if we don't manually clean the build directory we
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -30,14 +30,14 @@ http = "1.1.0"
 lazy_static = "1.4.0"
 log = "0.4.17"
 mime = "0.3.17"
-pyo3 = { version = "0.21.0", features = [
+pyo3 = { version = "0.23.2", features = [
    "macros",
    "anyhow",
    "abi3",
    "abi3-py38",
 ] }
-pyo3-log = "0.10.0"
-pythonize = "0.21.0"
+pyo3-log = "0.12.0"
+pythonize = "0.23.0"
 regex = "1.6.0"
 sha2 = "0.10.8"
 serde = { version = "1.0.144", features = ["derive"] }
--- a/rust/benches/evaluator.rs
+++ b/rust/benches/evaluator.rs
@@ -60,6 +60,7 @@ fn bench_match_exact(b: &mut Bencher) {
        true,
        vec![],
        false,
+        false,
    )
    .unwrap();

@@ -105,6 +106,7 @@ fn bench_match_word(b: &mut Bencher) {
        true,
        vec![],
        false,
+        false,
    )
    .unwrap();

@@ -150,6 +152,7 @@ fn bench_match_word_miss(b: &mut Bencher) {
        true,
        vec![],
        false,
+        false,
    )
    .unwrap();

@@ -195,6 +198,7 @@ fn bench_eval_message(b: &mut Bencher) {
        true,
        vec![],
        false,
+        false,
    )
    .unwrap();

@@ -205,6 +209,7 @@ fn bench_eval_message(b: &mut Bencher) {
        false,
        false,
        false,
+        false,
    );

    b.iter(|| eval.run(&rules, Some("bob"), Some("person")));
--- a/rust/src/acl/mod.rs
+++ b/rust/src/acl/mod.rs
@@ -32,14 +32,14 @@ use crate::push::utils::{glob_to_regex, GlobMatchType};

 /// Called when registering modules with python.
 pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
-    let child_module = PyModule::new_bound(py, "acl")?;
+    let child_module = PyModule::new(py, "acl")?;
    child_module.add_class::<ServerAclEvaluator>()?;

    m.add_submodule(&child_module)?;

    // We need to manually add the module to sys.modules to make `from
    // synapse.synapse_rust import acl` work.
-    py.import_bound("sys")?
+    py.import("sys")?
        .getattr("modules")?
        .set_item("synapse.synapse_rust.acl", child_module)?;

--- a/rust/src/events/filter.rs
+++ b/rust/src/events/filter.rs
@@ -0,0 +1,107 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2024 New Vector, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+use std::collections::HashMap;
+
+use pyo3::{exceptions::PyValueError, pyfunction, PyResult};
+
+use crate::{
+    identifier::UserID,
+    matrix_const::{
+        HISTORY_VISIBILITY_INVITED, HISTORY_VISIBILITY_JOINED, MEMBERSHIP_INVITE, MEMBERSHIP_JOIN,
+    },
+};
+
+#[pyfunction(name = "event_visible_to_server")]
+pub fn event_visible_to_server_py(
+    sender: String,
+    target_server_name: String,
+    history_visibility: String,
+    erased_senders: HashMap<String, bool>,
+    partial_state_invisible: bool,
+    memberships: Vec<(String, String)>, // (state_key, membership)
+) -> PyResult<bool> {
+    event_visible_to_server(
+        sender,
+        target_server_name,
+        history_visibility,
+        erased_senders,
+        partial_state_invisible,
+        memberships,
+    )
+    .map_err(|e| PyValueError::new_err(format!("{e}")))
+}
+
+/// Return whether the target server is allowed to see the event.
+///
+/// For a fully stated room, the target server is allowed to see an event E if:
+///   - the state at E has world readable or shared history vis, OR
+///   - the state at E says that the target server is in the room.
+///
+/// For a partially stated room, the target server is allowed to see E if:
+///   - E was created by this homeserver, AND:
+///       - the partial state at E has world readable or shared history vis, OR
+///       - the partial state at E says that the target server is in the room.
+pub fn event_visible_to_server(
+    sender: String,
+    target_server_name: String,
+    history_visibility: String,
+    erased_senders: HashMap<String, bool>,
+    partial_state_invisible: bool,
+    memberships: Vec<(String, String)>, // (state_key, membership)
+) -> anyhow::Result<bool> {
+    if let Some(&erased) = erased_senders.get(&sender) {
+        if erased {
+            return Ok(false);
+        }
+    }
+
+    if partial_state_invisible {
+        return Ok(false);
+    }
+
+    if history_visibility != HISTORY_VISIBILITY_INVITED
+        && history_visibility != HISTORY_VISIBILITY_JOINED
+    {
+        return Ok(true);
+    }
+
+    let mut visible = false;
+    for (state_key, membership) in memberships {
+        let state_key = UserID::try_from(state_key.as_ref())
+            .map_err(|e| anyhow::anyhow!(format!("invalid user_id ({state_key}): {e}")))?;
+        if state_key.server_name() != target_server_name {
+            return Err(anyhow::anyhow!(
+                "state_key.server_name ({}) does not match target_server_name ({target_server_name})",
+                state_key.server_name()
+            ));
+        }
+
+        match membership.as_str() {
+            MEMBERSHIP_INVITE => {
+                if history_visibility == HISTORY_VISIBILITY_INVITED {
+                    visible = true;
+                    break;
+                }
+            }
+            MEMBERSHIP_JOIN => {
+                visible = true;
+                break;
+            }
+            _ => continue,
+        }
+    }
+
+    Ok(visible)
+}
--- a/rust/src/events/internal_metadata.rs
+++ b/rust/src/events/internal_metadata.rs
@@ -41,9 +41,11 @@ use pyo3::{
    pybacked::PyBackedStr,
    pyclass, pymethods,
    types::{PyAnyMethods, PyDict, PyDictMethods, PyString},
-    Bound, IntoPy, PyAny, PyObject, PyResult, Python,
+    Bound, IntoPyObject, PyAny, PyObject, PyResult, Python,
 };

+use crate::UnwrapInfallible;
+
 /// Definitions of the various fields of the internal metadata.
 #[derive(Clone)]
 enum EventInternalMetadataData {
@@ -60,31 +62,59 @@ enum EventInternalMetadataData {

 impl EventInternalMetadataData {
    /// Convert the field to its name and python object.
-    fn to_python_pair<'a>(&self, py: Python<'a>) -> (&'a Bound<'a, PyString>, PyObject) {
+    fn to_python_pair<'a>(&self, py: Python<'a>) -> (&'a Bound<'a, PyString>, Bound<'a, PyAny>) {
        match self {
-            EventInternalMetadataData::OutOfBandMembership(o) => {
-                (pyo3::intern!(py, "out_of_band_membership"), o.into_py(py))
-            }
-            EventInternalMetadataData::SendOnBehalfOf(o) => {
-                (pyo3::intern!(py, "send_on_behalf_of"), o.into_py(py))
-            }
-            EventInternalMetadataData::RecheckRedaction(o) => {
-                (pyo3::intern!(py, "recheck_redaction"), o.into_py(py))
-            }
-            EventInternalMetadataData::SoftFailed(o) => {
-                (pyo3::intern!(py, "soft_failed"), o.into_py(py))
-            }
-            EventInternalMetadataData::ProactivelySend(o) => {
-                (pyo3::intern!(py, "proactively_send"), o.into_py(py))
-            }
-            EventInternalMetadataData::Redacted(o) => {
-                (pyo3::intern!(py, "redacted"), o.into_py(py))
-            }
-            EventInternalMetadataData::TxnId(o) => (pyo3::intern!(py, "txn_id"), o.into_py(py)),
-            EventInternalMetadataData::TokenId(o) => (pyo3::intern!(py, "token_id"), o.into_py(py)),
-            EventInternalMetadataData::DeviceId(o) => {
-                (pyo3::intern!(py, "device_id"), o.into_py(py))
-            }
+            EventInternalMetadataData::OutOfBandMembership(o) => (
+                pyo3::intern!(py, "out_of_band_membership"),
+                o.into_pyobject(py)
+                    .unwrap_infallible()
+                    .to_owned()
+                    .into_any(),
+            ),
+            EventInternalMetadataData::SendOnBehalfOf(o) => (
+                pyo3::intern!(py, "send_on_behalf_of"),
+                o.into_pyobject(py).unwrap_infallible().into_any(),
+            ),
+            EventInternalMetadataData::RecheckRedaction(o) => (
+                pyo3::intern!(py, "recheck_redaction"),
+                o.into_pyobject(py)
+                    .unwrap_infallible()
+                    .to_owned()
+                    .into_any(),
+            ),
+            EventInternalMetadataData::SoftFailed(o) => (
+                pyo3::intern!(py, "soft_failed"),
+                o.into_pyobject(py)
+                    .unwrap_infallible()
+                    .to_owned()
+                    .into_any(),
+            ),
+            EventInternalMetadataData::ProactivelySend(o) => (
+                pyo3::intern!(py, "proactively_send"),
+                o.into_pyobject(py)
+                    .unwrap_infallible()
+                    .to_owned()
+                    .into_any(),
+            ),
+            EventInternalMetadataData::Redacted(o) => (
+                pyo3::intern!(py, "redacted"),
+                o.into_pyobject(py)
+                    .unwrap_infallible()
+                    .to_owned()
+                    .into_any(),
+            ),
+            EventInternalMetadataData::TxnId(o) => (
+                pyo3::intern!(py, "txn_id"),
+                o.into_pyobject(py).unwrap_infallible().into_any(),
+            ),
+            EventInternalMetadataData::TokenId(o) => (
+                pyo3::intern!(py, "token_id"),
+                o.into_pyobject(py).unwrap_infallible().into_any(),
+            ),
+            EventInternalMetadataData::DeviceId(o) => (
+                pyo3::intern!(py, "device_id"),
+                o.into_pyobject(py).unwrap_infallible().into_any(),
+            ),
        }
    }

@@ -247,7 +277,7 @@ impl EventInternalMetadata {
    ///
    /// Note that `outlier` and `stream_ordering` are stored in separate columns so are not returned here.
    fn get_dict(&self, py: Python<'_>) -> PyResult<PyObject> {
-        let dict = PyDict::new_bound(py);
+        let dict = PyDict::new(py);

        for entry in &self.data {
            let (key, value) = entry.to_python_pair(py);
--- a/rust/src/events/mod.rs
+++ b/rust/src/events/mod.rs
@@ -22,21 +22,23 @@

 use pyo3::{
    types::{PyAnyMethods, PyModule, PyModuleMethods},
-    Bound, PyResult, Python,
+    wrap_pyfunction, Bound, PyResult, Python,
 };

+pub mod filter;
 mod internal_metadata;

 /// Called when registering modules with python.
 pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
-    let child_module = PyModule::new_bound(py, "events")?;
+    let child_module = PyModule::new(py, "events")?;
    child_module.add_class::<internal_metadata::EventInternalMetadata>()?;
+    child_module.add_function(wrap_pyfunction!(filter::event_visible_to_server_py, m)?)?;

    m.add_submodule(&child_module)?;

    // We need to manually add the module to sys.modules to make `from
    // synapse.synapse_rust import events` work.
-    py.import_bound("sys")?
+    py.import("sys")?
        .getattr("modules")?
        .set_item("synapse.synapse_rust.events", child_module)?;

--- a/rust/src/http.rs
+++ b/rust/src/http.rs
@@ -70,7 +70,7 @@ pub fn http_request_from_twisted(request: &Bound<'_, PyAny>) -> PyResult<Request
    let headers_iter = request
        .getattr("requestHeaders")?
        .call_method0("getAllRawHeaders")?
-        .iter()?;
+        .try_iter()?;

    for header in headers_iter {
        let header = header?;
--- a/rust/src/identifier.rs
+++ b/rust/src/identifier.rs
@@ -0,0 +1,252 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2024 New Vector, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+//! # Matrix Identifiers
+//!
+//! This module contains definitions and utilities for working with matrix identifiers.
+
+use std::{fmt, ops::Deref};
+
+/// Errors that can occur when parsing a matrix identifier.
+#[derive(Clone, Debug, PartialEq)]
+pub enum IdentifierError {
+    IncorrectSigil,
+    MissingColon,
+}
+
+impl fmt::Display for IdentifierError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+/// A Matrix user_id.
+#[derive(Clone, Debug, PartialEq)]
+pub struct UserID(String);
+
+impl UserID {
+    /// Returns the `localpart` of the user_id.
+    pub fn localpart(&self) -> &str {
+        &self[1..self.colon_pos()]
+    }
+
+    /// Returns the `server_name` / `domain` of the user_id.
+    pub fn server_name(&self) -> &str {
+        &self[self.colon_pos() + 1..]
+    }
+
+    /// Returns the position of the ':' inside of the user_id.
+    /// Used when splitting the user_id into it's respective parts.
+    fn colon_pos(&self) -> usize {
+        self.find(':').unwrap()
+    }
+}
+
+impl TryFrom<&str> for UserID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `UserID` from the provided `&str`.
+    /// Can fail if the user_id is incorrectly formatted.
+    fn try_from(s: &str) -> Result<Self, Self::Error> {
+        if !s.starts_with('@') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        if s.find(':').is_none() {
+            return Err(IdentifierError::MissingColon);
+        }
+
+        Ok(UserID(s.to_string()))
+    }
+}
+
+impl TryFrom<String> for UserID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `UserID` from the provided `&str`.
+    /// Can fail if the user_id is incorrectly formatted.
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        if !s.starts_with('@') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        if s.find(':').is_none() {
+            return Err(IdentifierError::MissingColon);
+        }
+
+        Ok(UserID(s))
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for UserID {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s: String = serde::Deserialize::deserialize(deserializer)?;
+        UserID::try_from(s).map_err(serde::de::Error::custom)
+    }
+}
+
+impl Deref for UserID {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl fmt::Display for UserID {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+/// A Matrix room_id.
+#[derive(Clone, Debug, PartialEq)]
+pub struct RoomID(String);
+
+impl RoomID {
+    /// Returns the `localpart` of the room_id.
+    pub fn localpart(&self) -> &str {
+        &self[1..self.colon_pos()]
+    }
+
+    /// Returns the `server_name` / `domain` of the room_id.
+    pub fn server_name(&self) -> &str {
+        &self[self.colon_pos() + 1..]
+    }
+
+    /// Returns the position of the ':' inside of the room_id.
+    /// Used when splitting the room_id into it's respective parts.
+    fn colon_pos(&self) -> usize {
+        self.find(':').unwrap()
+    }
+}
+
+impl TryFrom<&str> for RoomID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `RoomID` from the provided `&str`.
+    /// Can fail if the room_id is incorrectly formatted.
+    fn try_from(s: &str) -> Result<Self, Self::Error> {
+        if !s.starts_with('!') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        if s.find(':').is_none() {
+            return Err(IdentifierError::MissingColon);
+        }
+
+        Ok(RoomID(s.to_string()))
+    }
+}
+
+impl TryFrom<String> for RoomID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `RoomID` from the provided `String`.
+    /// Can fail if the room_id is incorrectly formatted.
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        if !s.starts_with('!') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        if s.find(':').is_none() {
+            return Err(IdentifierError::MissingColon);
+        }
+
+        Ok(RoomID(s))
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for RoomID {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s: String = serde::Deserialize::deserialize(deserializer)?;
+        RoomID::try_from(s).map_err(serde::de::Error::custom)
+    }
+}
+
+impl Deref for RoomID {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl fmt::Display for RoomID {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+/// A Matrix event_id.
+#[derive(Clone, Debug, PartialEq)]
+pub struct EventID(String);
+
+impl TryFrom<&str> for EventID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `EventID` from the provided `&str`.
+    /// Can fail if the event_id is incorrectly formatted.
+    fn try_from(s: &str) -> Result<Self, Self::Error> {
+        if !s.starts_with('$') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        Ok(EventID(s.to_string()))
+    }
+}
+
+impl TryFrom<String> for EventID {
+    type Error = IdentifierError;
+
+    /// Will try creating a `EventID` from the provided `String`.
+    /// Can fail if the event_id is incorrectly formatted.
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        if !s.starts_with('$') {
+            return Err(IdentifierError::IncorrectSigil);
+        }
+
+        Ok(EventID(s))
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for EventID {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s: String = serde::Deserialize::deserialize(deserializer)?;
+        EventID::try_from(s).map_err(serde::de::Error::custom)
+    }
+}
+
+impl Deref for EventID {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl fmt::Display for EventID {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -1,3 +1,5 @@
+use std::convert::Infallible;
+
 use lazy_static::lazy_static;
 use pyo3::prelude::*;
 use pyo3_log::ResetHandle;
@@ -6,6 +8,8 @@ pub mod acl;
 pub mod errors;
 pub mod events;
 pub mod http;
+pub mod identifier;
+pub mod matrix_const;
 pub mod push;
 pub mod rendezvous;

@@ -50,3 +54,16 @@ fn synapse_rust(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {

    Ok(())
 }
+
+pub trait UnwrapInfallible<T> {
+    fn unwrap_infallible(self) -> T;
+}
+
+impl<T> UnwrapInfallible<T> for Result<T, Infallible> {
+    fn unwrap_infallible(self) -> T {
+        match self {
+            Ok(val) => val,
+            Err(never) => match never {},
+        }
+    }
+}
--- a/rust/src/matrix_const.rs
+++ b/rust/src/matrix_const.rs
@@ -0,0 +1,28 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2024 New Vector, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+//! # Matrix Constants
+//!
+//! This module contains definitions for constant values described by the matrix specification.
+
+pub const HISTORY_VISIBILITY_WORLD_READABLE: &str = "world_readable";
+pub const HISTORY_VISIBILITY_SHARED: &str = "shared";
+pub const HISTORY_VISIBILITY_INVITED: &str = "invited";
+pub const HISTORY_VISIBILITY_JOINED: &str = "joined";
+
+pub const MEMBERSHIP_BAN: &str = "ban";
+pub const MEMBERSHIP_LEAVE: &str = "leave";
+pub const MEMBERSHIP_KNOCK: &str = "knock";
+pub const MEMBERSHIP_INVITE: &str = "invite";
+pub const MEMBERSHIP_JOIN: &str = "join";
--- a/rust/src/push/base_rules.rs
+++ b/rust/src/push/base_rules.rs
@@ -81,7 +81,7 @@ pub const BASE_APPEND_OVERRIDE_RULES: &[PushRule] = &[
        ))]),
        actions: Cow::Borrowed(&[Action::Notify]),
        default: true,
-        default_enabled: false,
+        default_enabled: true,
    },
    PushRule {
        rule_id: Cow::Borrowed("global/override/.m.rule.suppress_notices"),
--- a/rust/src/push/evaluator.rs
+++ b/rust/src/push/evaluator.rs
@@ -105,6 +105,9 @@ pub struct PushRuleEvaluator {
    /// If MSC3931 (room version feature flags) is enabled. Usually controlled by the same
    /// flag as MSC1767 (extensible events core).
    msc3931_enabled: bool,
+
+    // If MSC4210 (remove legacy mentions) is enabled.
+    msc4210_enabled: bool,
 }

 #[pymethods]
@@ -122,6 +125,7 @@ impl PushRuleEvaluator {
        related_event_match_enabled,
        room_version_feature_flags,
        msc3931_enabled,
+        msc4210_enabled,
    ))]
    pub fn py_new(
        flattened_keys: BTreeMap<String, JsonValue>,
@@ -133,6 +137,7 @@ impl PushRuleEvaluator {
        related_event_match_enabled: bool,
        room_version_feature_flags: Vec<String>,
        msc3931_enabled: bool,
+        msc4210_enabled: bool,
    ) -> Result<Self, Error> {
        let body = match flattened_keys.get("content.body") {
            Some(JsonValue::Value(SimpleJsonValue::Str(s))) => s.clone().into_owned(),
@@ -150,6 +155,7 @@ impl PushRuleEvaluator {
            related_event_match_enabled,
            room_version_feature_flags,
            msc3931_enabled,
+            msc4210_enabled,
        })
    }

@@ -161,6 +167,7 @@ impl PushRuleEvaluator {
    ///
    /// Returns the set of actions, if any, that match (filtering out any
    /// `dont_notify` and `coalesce` actions).
+    #[pyo3(signature = (push_rules, user_id=None, display_name=None))]
    pub fn run(
        &self,
        push_rules: &FilteredPushRules,
@@ -176,7 +183,8 @@ impl PushRuleEvaluator {

            // For backwards-compatibility the legacy mention rules are disabled
            // if the event contains the 'm.mentions' property.
-            if self.has_mentions
+            // Additionally, MSC4210 always disables the legacy rules.
+            if (self.has_mentions || self.msc4210_enabled)
                && (rule_id == "global/override/.m.rule.contains_display_name"
                    || rule_id == "global/content/.m.rule.contains_user_name"
                    || rule_id == "global/override/.m.rule.roomnotif")
@@ -229,6 +237,7 @@ impl PushRuleEvaluator {
    }

    /// Check if the given condition matches.
+    #[pyo3(signature = (condition, user_id=None, display_name=None))]
    fn matches(
        &self,
        condition: Condition,
@@ -526,6 +535,7 @@ fn push_rule_evaluator() {
        true,
        vec![],
        true,
+        false,
    )
    .unwrap();

@@ -555,6 +565,7 @@ fn test_requires_room_version_supports_condition() {
        false,
        flags,
        true,
+        false,
    )
    .unwrap();

@@ -582,7 +593,7 @@ fn test_requires_room_version_supports_condition() {
    };
    let rules = PushRules::new(vec![custom_rule]);
    result = evaluator.run(
-        &FilteredPushRules::py_new(rules, BTreeMap::new(), true, false, true, false),
+        &FilteredPushRules::py_new(rules, BTreeMap::new(), true, false, true, false, false),
        None,
        None,
    );
--- a/rust/src/push/mod.rs
+++ b/rust/src/push/mod.rs
@@ -65,8 +65,8 @@ use anyhow::{Context, Error};
 use log::warn;
 use pyo3::exceptions::PyTypeError;
 use pyo3::prelude::*;
-use pyo3::types::{PyBool, PyList, PyLong, PyString};
-use pythonize::{depythonize_bound, pythonize};
+use pyo3::types::{PyBool, PyInt, PyList, PyString};
+use pythonize::{depythonize, pythonize, PythonizeError};
 use serde::de::Error as _;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
@@ -79,7 +79,7 @@ pub mod utils;

 /// Called when registering modules with python.
 pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
-    let child_module = PyModule::new_bound(py, "push")?;
+    let child_module = PyModule::new(py, "push")?;
    child_module.add_class::<PushRule>()?;
    child_module.add_class::<PushRules>()?;
    child_module.add_class::<FilteredPushRules>()?;
@@ -90,7 +90,7 @@ pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()>

    // We need to manually add the module to sys.modules to make `from
    // synapse.synapse_rust import push` work.
-    py.import_bound("sys")?
+    py.import("sys")?
        .getattr("modules")?
        .set_item("synapse.synapse_rust.push", child_module)?;

@@ -182,12 +182,16 @@ pub enum Action {
    Unknown(Value),
 }

-impl IntoPy<PyObject> for Action {
-    fn into_py(self, py: Python<'_>) -> PyObject {
+impl<'py> IntoPyObject<'py> for Action {
+    type Target = PyAny;
+    type Output = Bound<'py, Self::Target>;
+    type Error = PythonizeError;
+
+    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
        // When we pass the `Action` struct to Python we want it to be converted
        // to a dict. We use `pythonize`, which converts the struct using the
        // `serde` serialization.
-        pythonize(py, &self).expect("valid action")
+        pythonize(py, &self)
    }
 }

@@ -270,13 +274,13 @@ pub enum SimpleJsonValue {
 }

 impl<'source> FromPyObject<'source> for SimpleJsonValue {
-    fn extract(ob: &'source PyAny) -> PyResult<Self> {
+    fn extract_bound(ob: &Bound<'source, PyAny>) -> PyResult<Self> {
        if let Ok(s) = ob.downcast::<PyString>() {
            Ok(SimpleJsonValue::Str(Cow::Owned(s.to_string())))
        // A bool *is* an int, ensure we try bool first.
        } else if let Ok(b) = ob.downcast::<PyBool>() {
            Ok(SimpleJsonValue::Bool(b.extract()?))
-        } else if let Ok(i) = ob.downcast::<PyLong>() {
+        } else if let Ok(i) = ob.downcast::<PyInt>() {
            Ok(SimpleJsonValue::Int(i.extract()?))
        } else if ob.is_none() {
            Ok(SimpleJsonValue::Null)
@@ -298,15 +302,19 @@ pub enum JsonValue {
 }

 impl<'source> FromPyObject<'source> for JsonValue {
-    fn extract(ob: &'source PyAny) -> PyResult<Self> {
+    fn extract_bound(ob: &Bound<'source, PyAny>) -> PyResult<Self> {
        if let Ok(l) = ob.downcast::<PyList>() {
-            match l.iter().map(SimpleJsonValue::extract).collect() {
+            match l
+                .iter()
+                .map(|it| SimpleJsonValue::extract_bound(&it))
+                .collect()
+            {
                Ok(a) => Ok(JsonValue::Array(a)),
                Err(e) => Err(PyTypeError::new_err(format!(
                    "Can't convert to JsonValue::Array: {e}"
                ))),
            }
-        } else if let Ok(v) = SimpleJsonValue::extract(ob) {
+        } else if let Ok(v) = SimpleJsonValue::extract_bound(ob) {
            Ok(JsonValue::Value(v))
        } else {
            Err(PyTypeError::new_err(format!(
@@ -363,15 +371,19 @@ pub enum KnownCondition {
    },
 }

-impl IntoPy<PyObject> for Condition {
-    fn into_py(self, py: Python<'_>) -> PyObject {
-        pythonize(py, &self).expect("valid condition")
+impl<'source> IntoPyObject<'source> for Condition {
+    type Target = PyAny;
+    type Output = Bound<'source, Self::Target>;
+    type Error = PythonizeError;
+
+    fn into_pyobject(self, py: Python<'source>) -> Result<Self::Output, Self::Error> {
+        pythonize(py, &self)
    }
 }

 impl<'source> FromPyObject<'source> for Condition {
    fn extract_bound(ob: &Bound<'source, PyAny>) -> PyResult<Self> {
-        Ok(depythonize_bound(ob.clone())?)
+        Ok(depythonize(ob)?)
    }
 }

@@ -534,6 +546,7 @@ pub struct FilteredPushRules {
    msc3381_polls_enabled: bool,
    msc3664_enabled: bool,
    msc4028_push_encrypted_events: bool,
+    msc4210_enabled: bool,
 }

 #[pymethods]
@@ -546,6 +559,7 @@ impl FilteredPushRules {
        msc3381_polls_enabled: bool,
        msc3664_enabled: bool,
        msc4028_push_encrypted_events: bool,
+        msc4210_enabled: bool,
    ) -> Self {
        Self {
            push_rules,
@@ -554,6 +568,7 @@ impl FilteredPushRules {
            msc3381_polls_enabled,
            msc3664_enabled,
            msc4028_push_encrypted_events,
+            msc4210_enabled,
        }
    }

@@ -596,6 +611,14 @@ impl FilteredPushRules {
                    return false;
                }

+                if self.msc4210_enabled
+                    && (rule.rule_id == "global/override/.m.rule.contains_display_name"
+                        || rule.rule_id == "global/content/.m.rule.contains_user_name"
+                        || rule.rule_id == "global/override/.m.rule.roomnotif")
+                {
+                    return false;
+                }
+
                true
            })
            .map(|r| {
--- a/rust/src/push/utils.rs
+++ b/rust/src/push/utils.rs
@@ -23,7 +23,6 @@ use anyhow::bail;
 use anyhow::Context;
 use anyhow::Error;
 use lazy_static::lazy_static;
-use regex;
 use regex::Regex;
 use regex::RegexBuilder;

--- a/rust/src/rendezvous/mod.rs
+++ b/rust/src/rendezvous/mod.rs
@@ -29,7 +29,7 @@ use pyo3::{
    exceptions::PyValueError,
    pyclass, pymethods,
    types::{PyAnyMethods, PyModule, PyModuleMethods},
-    Bound, Py, PyAny, PyObject, PyResult, Python, ToPyObject,
+    Bound, IntoPyObject, Py, PyAny, PyObject, PyResult, Python,
 };
 use ulid::Ulid;

@@ -37,6 +37,7 @@ use self::session::Session;
 use crate::{
    errors::{NotFoundError, SynapseError},
    http::{http_request_from_twisted, http_response_to_twisted, HeaderMapPyExt},
+    UnwrapInfallible,
 };

 mod session;
@@ -125,7 +126,11 @@ impl RendezvousHandler {
        let base = Uri::try_from(format!("{base}_synapse/client/rendezvous"))
            .map_err(|_| PyValueError::new_err("Invalid base URI"))?;

-        let clock = homeserver.call_method0("get_clock")?.to_object(py);
+        let clock = homeserver
+            .call_method0("get_clock")?
+            .into_pyobject(py)
+            .unwrap_infallible()
+            .unbind();

        // Construct a Python object so that we can get a reference to the
        // evict method and schedule it to run.
@@ -288,6 +293,13 @@ impl RendezvousHandler {
        let mut response = Response::new(Bytes::new());
        *response.status_mut() = StatusCode::ACCEPTED;
        prepare_headers(response.headers_mut(), session);
+
+        // Even though this isn't mandated by the MSC, we set a Content-Type on the response. It
+        // doesn't do any harm as the body is empty, but this helps escape a bug in some reverse
+        // proxy/cache setup which strips the ETag header if there is no Content-Type set.
+        // Specifically, we noticed this behaviour when placing Synapse behind Cloudflare.
+        response.headers_mut().typed_insert(ContentType::text());
+
        http_response_to_twisted(twisted_request, response)?;

        Ok(())
@@ -311,7 +323,7 @@ impl RendezvousHandler {
 }

 pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
-    let child_module = PyModule::new_bound(py, "rendezvous")?;
+    let child_module = PyModule::new(py, "rendezvous")?;

    child_module.add_class::<RendezvousHandler>()?;

@@ -319,7 +331,7 @@ pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()>

    // We need to manually add the module to sys.modules to make `from
    // synapse.synapse_rust import rendezvous` work.
-    py.import_bound("sys")?
+    py.import("sys")?
        .getattr("modules")?
        .set_item("synapse.synapse_rust.rendezvous", child_module)?;

--- a/scripts-dev/build_debian_packages.py
+++ b/scripts-dev/build_debian_packages.py
@@ -28,12 +28,11 @@ from typing import Collection, Optional, Sequence, Set
 # example)
 DISTS = (
    "debian:bullseye",  # (EOL ~2024-07) (our EOL forced by Python 3.9 is 2025-10-05)
-    "debian:bookworm",  # (EOL not specified yet) (our EOL forced by Python 3.11 is 2027-10-24)
-    "debian:sid",  # (EOL not specified yet) (our EOL forced by Python 3.11 is 2027-10-24)
-    "ubuntu:focal",  # 20.04 LTS (EOL 2025-04) (our EOL forced by Python 3.8 is 2024-10-14)
+    "debian:bookworm",  # (EOL 2026-06) (our EOL forced by Python 3.11 is 2027-10-24)
+    "debian:sid",  # (rolling distro, no EOL)
    "ubuntu:jammy",  # 22.04 LTS (EOL 2027-04) (our EOL forced by Python 3.10 is 2026-10-04)
-    "ubuntu:lunar",  # 23.04 (EOL 2024-01) (our EOL forced by Python 3.11 is 2027-10-24)
-    "ubuntu:mantic",  # 23.10 (EOL 2024-07) (our EOL forced by Python 3.11 is 2027-10-24)
+    "ubuntu:noble",  # 24.04 LTS (EOL 2029-06)
+    "ubuntu:oracular",  # 24.10 (EOL 2025-07)
    "debian:trixie",  # (EOL not specified yet)
 )

--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -195,6 +195,10 @@ if [ -z "$skip_docker_build" ]; then
        # Build the unified Complement image (from the worker Synapse image we just built).
        echo_if_github "::group::Build Docker image: complement/Dockerfile"
        $CONTAINER_RUNTIME build -t complement-synapse \
+            `# This is the tag we end up pushing to the registry (see` \
+            `# .github/workflows/push_complement_image.yml) so let's just label it now` \
+            `# so people can reference it by the same name locally.` \
+            -t ghcr.io/element-hq/synapse/complement-synapse \
            -f "docker/complement/Dockerfile" "docker/complement"
        echo_if_github "::endgroup::"

--- a/scripts-dev/mypy_synapse_plugin.py
+++ b/scripts-dev/mypy_synapse_plugin.py
@@ -360,7 +360,7 @@ def is_cacheable(
        # For a type alias, check if the underlying real type is cachable.
        return is_cacheable(mypy.types.get_proper_type(rt), signature, verbose)

-    elif isinstance(rt, UninhabitedType) and rt.is_noreturn:
+    elif isinstance(rt, UninhabitedType):
        # There is no return value, just consider it cachable. This is only used
        # in tests.
        return True, None
--- a/scripts-dev/release.py
+++ b/scripts-dev/release.py
@@ -40,7 +40,7 @@ import commonmark
 import git
 from click.exceptions import ClickException
 from git import GitCommandError, Repo
-from github import Github
+from github import BadCredentialsException, Github
 from packaging import version


@@ -323,10 +323,8 @@ def tag(gh_token: Optional[str]) -> None:
 def _tag(gh_token: Optional[str]) -> None:
    """Tags the release and generates a draft GitHub release"""

-    if gh_token:
-        # Test that the GH Token is valid before continuing.
-        gh = Github(gh_token)
-        gh.get_user()
+    # Test that the GH Token is valid before continuing.
+    check_valid_gh_token(gh_token)

    # Make sure we're in a git repo.
    repo = get_repo_and_check_clean_checkout()
@@ -469,10 +467,8 @@ def upload(gh_token: Optional[str]) -> None:
 def _upload(gh_token: Optional[str]) -> None:
    """Upload release to pypi."""

-    if gh_token:
-        # Test that the GH Token is valid before continuing.
-        gh = Github(gh_token)
-        gh.get_user()
+    # Test that the GH Token is valid before continuing.
+    check_valid_gh_token(gh_token)

    current_version = get_package_version()
    tag_name = f"v{current_version}"
@@ -569,10 +565,8 @@ def wait_for_actions(gh_token: Optional[str]) -> None:


 def _wait_for_actions(gh_token: Optional[str]) -> None:
-    if gh_token:
-        # Test that the GH Token is valid before continuing.
-        gh = Github(gh_token)
-        gh.get_user()
+    # Test that the GH Token is valid before continuing.
+    check_valid_gh_token(gh_token)

    # Find out the version and tag name.
    current_version = get_package_version()
@@ -806,6 +800,22 @@ def get_repo_and_check_clean_checkout(
    return repo


+def check_valid_gh_token(gh_token: Optional[str]) -> None:
+    """Check that a github token is valid, if supplied"""
+
+    if not gh_token:
+        # No github token supplied, so nothing to do.
+        return
+
+    try:
+        gh = Github(gh_token)
+
+        # We need to lookup name to trigger a request.
+        _name = gh.get_user().name
+    except BadCredentialsException as e:
+        raise click.ClickException(f"Github credentials are bad: {e}")
+
+
 def find_ref(repo: git.Repo, ref_name: str) -> Optional[git.HEAD]:
    """Find the branch/ref, looking first locally then in the remote."""
    if ref_name in repo.references:
--- a/synapse/init.py
+++ b/synapse/init.py
@@ -39,8 +39,8 @@ ImageFile.LOAD_TRUNCATED_IMAGES = True
 # Note that we use an (unneeded) variable here so that pyupgrade doesn't nuke the
 # if-statement completely.
 py_version = sys.version_info
-if py_version < (3, 8):
-    print("Synapse requires Python 3.8 or above.")
+if py_version < (3, 9):
+    print("Synapse requires Python 3.9 or above.")
    sys.exit(1)

 # Allow using the asyncio reactor via env var.
--- a/synapse/_scripts/synapse_port_db.py
+++ b/synapse/_scripts/synapse_port_db.py
@@ -88,6 +88,7 @@ from synapse.storage.databases.main.relations import RelationsWorkerStore
 from synapse.storage.databases.main.room import RoomBackgroundUpdateStore
 from synapse.storage.databases.main.roommember import RoomMemberBackgroundUpdateStore
 from synapse.storage.databases.main.search import SearchBackgroundUpdateStore
+from synapse.storage.databases.main.sliding_sync import SlidingSyncStore
 from synapse.storage.databases.main.state import MainStateBackgroundUpdateStore
 from synapse.storage.databases.main.stats import StatsStore
 from synapse.storage.databases.main.user_directory import (
@@ -255,6 +256,7 @@ class Store(
    ReceiptsBackgroundUpdateStore,
    RelationsWorkerStore,
    EventFederationWorkerStore,
+    SlidingSyncStore,
 ):
    def execute(self, f: Callable[..., R], *args: Any, **kwargs: Any) -> Awaitable[R]:
        return self.db_pool.runInteraction(f.__name__, f, *args, **kwargs)
--- a/synapse/api/auth/msc3861_delegated.py
+++ b/synapse/api/auth/msc3861_delegated.py
@@ -338,7 +338,7 @@ class MSC3861DelegatedAuth(BaseAuth):
            logger.exception("Failed to introspect token")
            raise SynapseError(503, "Unable to introspect the access token")

-        logger.info(f"Introspection result: {introspection_result!r}")
+        logger.debug("Introspection result: %r", introspection_result)

        # TODO: introspection verification should be more extensive, especially:
        #   - verify the audience
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -231,6 +231,8 @@ class EventContentFields:
    ROOM_NAME: Final = "name"

    MEMBERSHIP: Final = "membership"
+    MEMBERSHIP_DISPLAYNAME: Final = "displayname"
+    MEMBERSHIP_AVATAR_URL: Final = "avatar_url"

    # Used in m.room.guest_access events.
    GUEST_ACCESS: Final = "guest_access"
@@ -318,3 +320,8 @@ class ApprovalNoticeMedium:
 class Direction(enum.Enum):
    BACKWARDS = "b"
    FORWARDS = "f"
+
+
+class ProfileFields:
+    DISPLAYNAME: Final = "displayname"
+    AVATAR_URL: Final = "avatar_url"
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -87,8 +87,7 @@ class Codes(str, Enum):
    WEAK_PASSWORD = "M_WEAK_PASSWORD"
    INVALID_SIGNATURE = "M_INVALID_SIGNATURE"
    USER_DEACTIVATED = "M_USER_DEACTIVATED"
-    # USER_LOCKED = "M_USER_LOCKED"
-    USER_LOCKED = "ORG_MATRIX_MSC3939_USER_LOCKED"
+    USER_LOCKED = "M_USER_LOCKED"
    NOT_YET_UPLOADED = "M_NOT_YET_UPLOADED"
    CANNOT_OVERWRITE_MEDIA = "M_CANNOT_OVERWRITE_MEDIA"

@@ -101,8 +100,9 @@ class Codes(str, Enum):
    # The account has been suspended on the server.
    # By opposition to `USER_DEACTIVATED`, this is a reversible measure
    # that can possibly be appealed and reverted.
-    # Part of MSC3823.
-    USER_ACCOUNT_SUSPENDED = "ORG.MATRIX.MSC3823.USER_ACCOUNT_SUSPENDED"
+    # Introduced by MSC3823
+    # https://github.com/matrix-org/matrix-spec-proposals/pull/3823
+    USER_ACCOUNT_SUSPENDED = "M_USER_SUSPENDED"

    BAD_ALIAS = "M_BAD_ALIAS"
    # For restricted join rules.
--- a/synapse/api/urls.py
+++ b/synapse/api/urls.py
@@ -23,7 +23,8 @@

 import hmac
 from hashlib import sha256
-from urllib.parse import urlencode
+from typing import Optional
+from urllib.parse import urlencode, urljoin

 from synapse.config import ConfigError
 from synapse.config.homeserver import HomeServerConfig
@@ -66,3 +67,42 @@ class ConsentURIBuilder:
            urlencode({"u": user_id, "h": mac}),
        )
        return consent_uri
+
+
+class LoginSSORedirectURIBuilder:
+    def __init__(self, hs_config: HomeServerConfig):
+        self._public_baseurl = hs_config.server.public_baseurl
+
+    def build_login_sso_redirect_uri(
+        self, *, idp_id: Optional[str], client_redirect_url: str
+    ) -> str:
+        """Build a `/login/sso/redirect` URI for the given identity provider.
+
+        Builds `/_matrix/client/v3/login/sso/redirect/{idpId}?redirectUrl=xxx` when `idp_id` is specified.
+        Otherwise, builds `/_matrix/client/v3/login/sso/redirect?redirectUrl=xxx` when `idp_id` is `None`.
+
+        Args:
+            idp_id: Optional ID of the identity provider
+            client_redirect_url: URL to redirect the user to after login
+
+        Returns
+            The URI to follow when choosing a specific identity provider.
+        """
+        base_url = urljoin(
+            self._public_baseurl,
+            f"{CLIENT_API_PREFIX}/v3/login/sso/redirect",
+        )
+
+        serialized_query_parameters = urlencode({"redirectUrl": client_redirect_url})
+
+        if idp_id:
+            resultant_url = urljoin(
+                # We have to add a trailing slash to the base URL to ensure that the
+                # last path segment is not stripped away when joining with another path.
+                f"{base_url}/",
+                f"{idp_id}?{serialized_query_parameters}",
+            )
+        else:
+            resultant_url = f"{base_url}?{serialized_query_parameters}"
+
+        return resultant_url
--- a/synapse/app/generic_worker.py
+++ b/synapse/app/generic_worker.py
@@ -3,7 +3,7 @@
 #
 # Copyright 2020 The Matrix.org Foundation C.I.C.
 # Copyright 2016 OpenMarket Ltd
-# Copyright (C) 2023 New Vector, Ltd
+# Copyright (C) 2023-2024 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as
--- a/synapse/appservice/init.py
+++ b/synapse/appservice/init.py
@@ -87,6 +87,7 @@ class ApplicationService:
        ip_range_whitelist: Optional[IPSet] = None,
        supports_ephemeral: bool = False,
        msc3202_transaction_extensions: bool = False,
+        msc4190_device_management: bool = False,
    ):
        self.token = token
        self.url = (
@@ -100,6 +101,7 @@ class ApplicationService:
        self.ip_range_whitelist = ip_range_whitelist
        self.supports_ephemeral = supports_ephemeral
        self.msc3202_transaction_extensions = msc3202_transaction_extensions
+        self.msc4190_device_management = msc4190_device_management

        if "|" in self.id:
            raise Exception("application service ID cannot contain '|' character")
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -183,6 +183,18 @@ def _load_appservice(
            "The `org.matrix.msc3202` option should be true or false if specified."
        )

+    # Opt-in flag for the MSC4190 behaviours.
+    # When enabled, the following C-S API endpoints change for appservices:
+    # - POST /register does not return an access token
+    # - PUT /devices/{device_id} creates a new device if one does not exist
+    # - DELETE /devices/{device_id} no longer requires UIA
+    # - POST /delete_devices/{device_id} no longer requires UIA
+    msc4190_enabled = as_info.get("io.element.msc4190", False)
+    if not isinstance(msc4190_enabled, bool):
+        raise ValueError(
+            "The `io.element.msc4190` option should be true or false if specified."
+        )
+
    return ApplicationService(
        token=as_info["as_token"],
        url=as_info["url"],
@@ -195,4 +207,5 @@ def _load_appservice(
        ip_range_whitelist=ip_range_whitelist,
        supports_ephemeral=supports_ephemeral,
        msc3202_transaction_extensions=msc3202_transaction_extensions,
+        msc4190_device_management=msc4190_enabled,
    )
--- a/synapse/config/cas.py
+++ b/synapse/config/cas.py
@@ -20,7 +20,7 @@
 #
 #

-from typing import Any, List
+from typing import Any, List, Optional

 from synapse.config.sso import SsoAttributeRequirement
 from synapse.types import JsonDict
@@ -46,7 +46,9 @@ class CasConfig(Config):

            # TODO Update this to a _synapse URL.
            public_baseurl = self.root.server.public_baseurl
-            self.cas_service_url = public_baseurl + "_matrix/client/r0/login/cas/ticket"
+            self.cas_service_url: Optional[str] = (
+                public_baseurl + "_matrix/client/r0/login/cas/ticket"
+            )

            self.cas_protocol_version = cas_config.get("protocol_version")
            if (
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -110,6 +110,7 @@ class EmailConfig(Config):
            raise ConfigError(
                "email.require_transport_security requires email.enable_tls to be true"
            )
+        self.email_tlsname = email_config.get("tlsname", None)

        if "app_name" in email_config:
            self.email_app_name = email_config["app_name"]
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -365,11 +365,6 @@ class ExperimentalConfig(Config):
        # MSC3874: Filtering /messages with rel_types / not_rel_types.
        self.msc3874_enabled: bool = experimental.get("msc3874_enabled", False)

-        # MSC3886: Simple client rendezvous capability
-        self.msc3886_endpoint: Optional[str] = experimental.get(
-            "msc3886_endpoint", None
-        )
-
        # MSC3890: Remotely silence local notifications
        # Note: This option requires "experimental_features.msc3391_enabled" to be
        # set to "true", in order to communicate account data deletions to clients.
@@ -441,9 +436,14 @@ class ExperimentalConfig(Config):
                ("experimental", "msc4108_delegation_endpoint"),
            )

-        self.msc3823_account_suspension = experimental.get(
-            "msc3823_account_suspension", False
-        )
-
        # MSC4151: Report room API (Client-Server API)
        self.msc4151_enabled: bool = experimental.get("msc4151_enabled", False)
+
+        # MSC4210: Remove legacy mentions
+        self.msc4210_enabled: bool = experimental.get("msc4210_enabled", False)
+
+        # MSC4222: Adding `state_after` to sync v2
+        self.msc4222_enabled: bool = experimental.get("msc4222_enabled", False)
+
+        # MSC4076: Add `disable_badge_count`` to pusher configuration
+        self.msc4076_enabled: bool = experimental.get("msc4076_enabled", False)
--- a/synapse/config/jwt.py
+++ b/synapse/config/jwt.py
@@ -38,6 +38,7 @@ class JWTConfig(Config):
            self.jwt_algorithm = jwt_config["algorithm"]

            self.jwt_subject_claim = jwt_config.get("subject_claim", "sub")
+            self.jwt_display_name_claim = jwt_config.get("display_name_claim")

            # The issuer and audiences are optional, if provided, it is asserted
            # that the claims exist on the JWT.
@@ -49,5 +50,6 @@ class JWTConfig(Config):
            self.jwt_secret = None
            self.jwt_algorithm = None
            self.jwt_subject_claim = None
+            self.jwt_display_name_claim = None
            self.jwt_issuer = None
            self.jwt_audiences = None
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -43,7 +43,7 @@ from unpaddedbase64 import decode_base64
 from synapse.types import JsonDict
 from synapse.util.stringutils import random_string, random_string_with_symbols

-from ._base import Config, ConfigError
+from ._base import Config, ConfigError, read_file

 if TYPE_CHECKING:
    from signedjson.key import VerifyKeyWithExpiry
@@ -91,6 +91,11 @@ To suppress this warning and continue using 'matrix.org', admins should set
 'suppress_key_server_warning' to 'true' in homeserver.yaml.
 --------------------------------------------------------------------------------"""

+CONFLICTING_MACAROON_SECRET_KEY_OPTS_ERROR = """\
+Conflicting options 'macaroon_secret_key' and 'macaroon_secret_key_path' are
+both defined in config file.
+"""
+
 logger = logging.getLogger(__name__)


@@ -166,10 +171,16 @@ class KeyConfig(Config):
            )
        )

-        macaroon_secret_key: Optional[str] = config.get(
-            "macaroon_secret_key", self.root.registration.registration_shared_secret
-        )
-
+        macaroon_secret_key = config.get("macaroon_secret_key")
+        macaroon_secret_key_path = config.get("macaroon_secret_key_path")
+        if macaroon_secret_key_path:
+            if macaroon_secret_key:
+                raise ConfigError(CONFLICTING_MACAROON_SECRET_KEY_OPTS_ERROR)
+            macaroon_secret_key = read_file(
+                macaroon_secret_key_path, "macaroon_secret_key_path"
+            ).strip()
+        if not macaroon_secret_key:
+            macaroon_secret_key = self.root.registration.registration_shared_secret
        if not macaroon_secret_key:
            # Unfortunately, there are people out there that don't have this
            # set. Lets just be "nice" and derive one from their secret key.
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -360,5 +360,6 @@ def setup_logging(
        "Licensed under the AGPL 3.0 license. Website: https://github.com/element-hq/synapse"
    )
    logging.info("Server hostname: %s", config.server.server_name)
+    logging.info("Public Base URL: %s", config.server.public_baseurl)
    logging.info("Instance name: %s", hs.get_instance_name())
    logging.info("Twisted reactor: %s", type(reactor).__name__)
--- a/synapse/config/redis.py
+++ b/synapse/config/redis.py
@@ -21,10 +21,15 @@

 from typing import Any

-from synapse.config._base import Config
+from synapse.config._base import Config, ConfigError, read_file
 from synapse.types import JsonDict
 from synapse.util.check_dependencies import check_requirements

+CONFLICTING_PASSWORD_OPTS_ERROR = """\
+You have configured both `redis.password` and `redis.password_path`.
+These are mutually incompatible.
+"""
+

 class RedisConfig(Config):
    section = "redis"
@@ -43,6 +48,17 @@ class RedisConfig(Config):
        self.redis_path = redis_config.get("path", None)
        self.redis_dbid = redis_config.get("dbid", None)
        self.redis_password = redis_config.get("password")
+        redis_password_path = redis_config.get("password_path")
+        if redis_password_path:
+            if self.redis_password:
+                raise ConfigError(CONFLICTING_PASSWORD_OPTS_ERROR)
+            self.redis_password = read_file(
+                redis_password_path,
+                (
+                    "redis",
+                    "password_path",
+                ),
+            ).strip()

        self.redis_use_tls = redis_config.get("use_tls", False)
        self.redis_certificate = redis_config.get("certificate_file", None)
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -22,7 +22,7 @@
 import logging
 import os
 from typing import Any, Dict, List, Tuple
-from urllib.request import getproxies_environment  # type: ignore
+from urllib.request import getproxies_environment

 import attr

@@ -272,9 +272,7 @@ class ContentRepositoryConfig(Config):
                remote_media_lifetime
            )

-        self.enable_authenticated_media = config.get(
-            "enable_authenticated_media", False
-        )
+        self.enable_authenticated_media = config.get("enable_authenticated_media", True)

    def generate_config_section(self, data_dir_path: str, **kwargs: Any) -> str:
        assert data_dir_path is not None
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -215,9 +215,6 @@ class HttpListenerConfig:
    additional_resources: Dict[str, dict] = attr.Factory(dict)
    tag: Optional[str] = None
    request_id_header: Optional[str] = None
-    # If true, the listener will return CORS response headers compatible with MSC3886:
-    # https://github.com/matrix-org/matrix-spec-proposals/pull/3886
-    experimental_cors_msc3886: bool = False


@attr.s(slots=True, frozen=True, auto_attribs=True)
@@ -335,8 +332,14 @@ class ServerConfig(Config):
            logger.info("Using default public_baseurl %s", public_baseurl)
        else:
            self.serve_client_wellknown = True
+            # Ensure that public_baseurl ends with a trailing slash
            if public_baseurl[-1] != "/":
                public_baseurl += "/"
+
+        # Scrutinize user-provided config
+        if not isinstance(public_baseurl, str):
+            raise ConfigError("Must be a string", ("public_baseurl",))
+
        self.public_baseurl = public_baseurl

        # check that public_baseurl is valid
@@ -1004,7 +1007,6 @@ def parse_listener_def(num: int, listener: Any) -> ListenerConfig:
            additional_resources=listener.get("additional_resources", {}),
            tag=listener.get("tag"),
            request_id_header=listener.get("request_id_header"),
-            experimental_cors_msc3886=listener.get("experimental_cors_msc3886", False),
        )

    if socket_path:
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -248,7 +248,7 @@ class EventContext(UnpersistedEventContextBase):
    @tag_args
    async def get_current_state_ids(
        self, state_filter: Optional["StateFilter"] = None
-    ) -> Optional[StateMap[str]]:
+    ) -> StateMap[str]:
        """
        Gets the room state map, including this event - ie, the state in ``state_group``

@@ -256,13 +256,12 @@ class EventContext(UnpersistedEventContextBase):
        not make it into the room state. This method will raise an exception if
        ``rejected`` is set.

+        It is also an error to access this for an outlier event.
+
        Arg:
           state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules

        Returns:
-            Returns None if state_group is None, which happens when the associated
-            event is an outlier.
-
            Maps a (type, state_key) to the event ID of the state event matching
            this tuple.
        """
@@ -300,7 +299,8 @@ class EventContext(UnpersistedEventContextBase):
            this tuple.
        """

-        assert self.state_group_before_event is not None
+        if self.state_group_before_event is None:
+            return {}
        return await self._storage.state.get_state_ids_for_group(
            self.state_group_before_event, state_filter
        )
--- a/synapse/federation/sender/init.py
+++ b/synapse/federation/sender/init.py
@@ -140,7 +140,6 @@ from typing import (
    Iterable,
    List,
    Optional,
-    Set,
    Tuple,
 )

@@ -170,7 +169,13 @@ from synapse.metrics.background_process_metrics import (
    run_as_background_process,
    wrap_as_background_process,
 )
-from synapse.types import JsonDict, ReadReceipt, RoomStreamToken, StrCollection
+from synapse.types import (
+    JsonDict,
+    ReadReceipt,
+    RoomStreamToken,
+    StrCollection,
+    get_domain_from_id,
+)
 from synapse.util import Clock
 from synapse.util.metrics import Measure
 from synapse.util.retryutils import filter_destinations_by_retry_limiter
@@ -297,12 +302,10 @@ class _DestinationWakeupQueue:
    # being woken up.
    _MAX_TIME_IN_QUEUE = 30.0

-    # The maximum duration in seconds between waking up consecutive destination
-    # queues.
-    _MAX_DELAY = 0.1
-
    sender: "FederationSender" = attr.ib()
    clock: Clock = attr.ib()
+    max_delay_s: int = attr.ib()
+
    queue: "OrderedDict[str, Literal[None]]" = attr.ib(factory=OrderedDict)
    processing: bool = attr.ib(default=False)

@@ -332,7 +335,7 @@ class _DestinationWakeupQueue:
            # We also add an upper bound to the delay, to gracefully handle the
            # case where the queue only has a few entries in it.
            current_sleep_seconds = min(
-                self._MAX_DELAY, self._MAX_TIME_IN_QUEUE / len(self.queue)
+                self.max_delay_s, self._MAX_TIME_IN_QUEUE / len(self.queue)
            )

            while self.queue:
@@ -416,19 +419,14 @@ class FederationSender(AbstractFederationSender):
        self._is_processing = False
        self._last_poked_id = -1

-        # map from room_id to a set of PerDestinationQueues which we believe are
-        # awaiting a call to flush_read_receipts_for_room. The presence of an entry
-        # here for a given room means that we are rate-limiting RR flushes to that room,
-        # and that there is a pending call to _flush_rrs_for_room in the system.
-        self._queues_awaiting_rr_flush_by_room: Dict[str, Set[PerDestinationQueue]] = {}
-
-        self._rr_txn_interval_per_room_ms = (
-            1000.0
-            / hs.config.ratelimiting.federation_rr_transactions_per_room_per_second
-        )
-
        self._external_cache = hs.get_external_cache()
-        self._destination_wakeup_queue = _DestinationWakeupQueue(self, self.clock)
+
+        rr_txn_interval_per_room_s = (
+            1.0 / hs.config.ratelimiting.federation_rr_transactions_per_room_per_second
+        )
+        self._destination_wakeup_queue = _DestinationWakeupQueue(
+            self, self.clock, max_delay_s=rr_txn_interval_per_room_s
+        )

        # Regularly wake up destinations that have outstanding PDUs to be caught up
        self.clock.looping_call_now(
@@ -745,37 +743,48 @@ class FederationSender(AbstractFederationSender):

        # Some background on the rate-limiting going on here.
        #
-        # It turns out that if we attempt to send out RRs as soon as we get them from
-        # a client, then we end up trying to do several hundred Hz of federation
-        # transactions. (The number of transactions scales as O(N^2) on the size of a
-        # room, since in a large room we have both more RRs coming in, and more servers
-        # to send them to.)
+        # It turns out that if we attempt to send out RRs as soon as we get them
+        # from a client, then we end up trying to do several hundred Hz of
+        # federation transactions. (The number of transactions scales as O(N^2)
+        # on the size of a room, since in a large room we have both more RRs
+        # coming in, and more servers to send them to.)
        #
-        # This leads to a lot of CPU load, and we end up getting behind. The solution
-        # currently adopted is as follows:
+        # This leads to a lot of CPU load, and we end up getting behind. The
+        # solution currently adopted is to differentiate between receipts and
+        # destinations we should immediately send to, and those we can trickle
+        # the receipts to.
        #
-        # The first receipt in a given room is sent out immediately, at time T0. Any
-        # further receipts are, in theory, batched up for N seconds, where N is calculated
-        # based on the number of servers in the room to achieve a transaction frequency
-        # of around 50Hz. So, for example, if there were 100 servers in the room, then
-        # N would be 100 / 50Hz = 2 seconds.
+        # The current logic is to send receipts out immediately if:
+        #   - the room is "small", i.e. there's only N servers to send receipts
+        #     to, and so sending out the receipts immediately doesn't cause too
+        #     much load; or
+        #   - the receipt is for an event that happened recently, as users
+        #     notice if receipts are delayed when they know other users are
+        #     currently reading the room; or
+        #   - the receipt is being sent to the server that sent the event, so
+        #     that users see receipts for their own receipts quickly.
        #
-        # Then, after T+N, we flush out any receipts that have accumulated, and restart
-        # the timer to flush out more receipts at T+2N, etc. If no receipts accumulate,
-        # we stop the cycle and go back to the start.
+        # For destinations that we should delay sending the receipt to, we queue
+        # the receipts up to be sent in the next transaction, but don't trigger
+        # a new transaction to be sent. We then add the destination to the
+        # `DestinationWakeupQueue`, which will slowly iterate over each
+        # destination and trigger a new transaction to be sent.
        #
-        # However, in practice, it is often possible to flush out receipts earlier: in
-        # particular, if we are sending a transaction to a given server anyway (for
-        # example, because we have a PDU or a RR in another room to send), then we may
-        # as well send out all of the pending RRs for that server. So it may be that
-        # by the time we get to T+N, we don't actually have any RRs left to send out.
-        # Nevertheless we continue to buffer up RRs for the room in question until we
-        # reach the point that no RRs arrive between timer ticks.
+        # However, in practice, it is often possible to send out delayed
+        # receipts earlier: in particular, if we are sending a transaction to a
+        # given server anyway (for example, because we have a PDU or a RR in
+        # another room to send), then we may as well send out all of the pending
+        # RRs for that server. So it may be that by the time we get to waking up
+        # the destination, we don't actually have any RRs left to send out.
        #
-        # For even more background, see https://github.com/matrix-org/synapse/issues/4730.
+        # For even more background, see
+        # https://github.com/matrix-org/synapse/issues/4730.

        room_id = receipt.room_id

+        # Local read receipts always have 1 event ID.
+        event_id = receipt.event_ids[0]
+
        # Work out which remote servers should be poked and poke them.
        domains_set = await self._storage_controllers.state.get_current_hosts_in_room_or_partial_state_approximation(
            room_id
@@ -797,49 +806,51 @@ class FederationSender(AbstractFederationSender):
        if not domains:
            return

-        queues_pending_flush = self._queues_awaiting_rr_flush_by_room.get(room_id)
+        # We now split which domains we want to wake up immediately vs which we
+        # want to delay waking up.
+        immediate_domains: StrCollection
+        delay_domains: StrCollection

-        # if there is no flush yet scheduled, we will send out these receipts with
-        # immediate flushes, and schedule the next flush for this room.
-        if queues_pending_flush is not None:
-            logger.debug("Queuing receipt for: %r", domains)
+        if len(domains) < 10:
+            # For "small" rooms send to all domains immediately
+            immediate_domains = domains
+            delay_domains = ()
        else:
-            logger.debug("Sending receipt to: %r", domains)
-            self._schedule_rr_flush_for_room(room_id, len(domains))
+            metadata = await self.store.get_metadata_for_event(
+                receipt.room_id, event_id
+            )
+            assert metadata is not None

-        for domain in domains:
+            sender_domain = get_domain_from_id(metadata.sender)
+
+            if self.clock.time_msec() - metadata.received_ts < 60_000:
+                # We always send receipts for recent messages immediately
+                immediate_domains = domains
+                delay_domains = ()
+            else:
+                # Otherwise, we delay waking up all destinations except for the
+                # sender's domain.
+                immediate_domains = []
+                delay_domains = []
+                for domain in domains:
+                    if domain == sender_domain:
+                        immediate_domains.append(domain)
+                    else:
+                        delay_domains.append(domain)
+
+        for domain in immediate_domains:
+            # Add to destination queue and wake the destination up
+            queue = self._get_per_destination_queue(domain)
+            queue.queue_read_receipt(receipt)
+            queue.attempt_new_transaction()
+
+        for domain in delay_domains:
+            # Add to destination queue...
            queue = self._get_per_destination_queue(domain)
            queue.queue_read_receipt(receipt)

-            # if there is already a RR flush pending for this room, then make sure this
-            # destination is registered for the flush
-            if queues_pending_flush is not None:
-                queues_pending_flush.add(queue)
-            else:
-                queue.flush_read_receipts_for_room(room_id)
-
-    def _schedule_rr_flush_for_room(self, room_id: str, n_domains: int) -> None:
-        # that is going to cause approximately len(domains) transactions, so now back
-        # off for that multiplied by RR_TXN_INTERVAL_PER_ROOM
-        backoff_ms = self._rr_txn_interval_per_room_ms * n_domains
-
-        logger.debug("Scheduling RR flush in %s in %d ms", room_id, backoff_ms)
-        self.clock.call_later(backoff_ms, self._flush_rrs_for_room, room_id)
-        self._queues_awaiting_rr_flush_by_room[room_id] = set()
-
-    def _flush_rrs_for_room(self, room_id: str) -> None:
-        queues = self._queues_awaiting_rr_flush_by_room.pop(room_id)
-        logger.debug("Flushing RRs in %s to %s", room_id, queues)
-
-        if not queues:
-            # no more RRs arrived for this room; we are done.
-            return
-
-        # schedule the next flush
-        self._schedule_rr_flush_for_room(room_id, len(queues))
-
-        for queue in queues:
-            queue.flush_read_receipts_for_room(room_id)
+            # ... and schedule the destination to be woken up.
+            self._destination_wakeup_queue.add_to_queue(domain)

    async def send_presence_to_destinations(
        self, states: Iterable[UserPresenceState], destinations: Iterable[str]
--- a/synapse/federation/sender/per_destination_queue.py
+++ b/synapse/federation/sender/per_destination_queue.py
@@ -156,7 +156,6 @@ class PerDestinationQueue:
        # Each receipt can only have a single receipt per
        # (room ID, receipt type, user ID, thread ID) tuple.
        self._pending_receipt_edus: List[Dict[str, Dict[str, Dict[str, dict]]]] = []
-        self._rrs_pending_flush = False

        # stream_id of last successfully sent to-device message.
        # NB: may be a long or an int.
@@ -258,15 +257,7 @@ class PerDestinationQueue:
                }
            )

-    def flush_read_receipts_for_room(self, room_id: str) -> None:
-        # If there are any pending receipts for this room then force-flush them
-        # in a new transaction.
-        for edu in self._pending_receipt_edus:
-            if room_id in edu:
-                self._rrs_pending_flush = True
-                self.attempt_new_transaction()
-                # No use in checking remaining EDUs if the room was found.
-                break
+        self.mark_new_data()

    def send_keyed_edu(self, edu: Edu, key: Hashable) -> None:
        self._pending_edus_keyed[(edu.edu_type, key)] = edu
@@ -603,12 +594,9 @@ class PerDestinationQueue:
                    self._destination, last_successful_stream_ordering
                )

-    def _get_receipt_edus(self, force_flush: bool, limit: int) -> Iterable[Edu]:
+    def _get_receipt_edus(self, limit: int) -> Iterable[Edu]:
        if not self._pending_receipt_edus:
            return
-        if not force_flush and not self._rrs_pending_flush:
-            # not yet time for this lot
-            return

        # Send at most limit EDUs for receipts.
        for content in self._pending_receipt_edus[:limit]:
@@ -747,7 +735,7 @@ class _TransactionQueueManager:
            )

        # Add read receipt EDUs.
-        pending_edus.extend(self.queue._get_receipt_edus(force_flush=False, limit=5))
+        pending_edus.extend(self.queue._get_receipt_edus(limit=5))
        edu_limit = MAX_EDUS_PER_TRANSACTION - len(pending_edus)

        # Next, prioritize to-device messages so that existing encryption channels
@@ -795,13 +783,6 @@ class _TransactionQueueManager:
        if not self._pdus and not pending_edus:
            return [], []

-        # if we've decided to send a transaction anyway, and we have room, we
-        # may as well send any pending RRs
-        if edu_limit:
-            pending_edus.extend(
-                self.queue._get_receipt_edus(force_flush=True, limit=edu_limit)
-            )
-
        if self._pdus:
            self._last_stream_ordering = self._pdus[
                -1
--- a/synapse/federation/transport/server/_base.py
+++ b/synapse/federation/transport/server/_base.py
@@ -113,7 +113,7 @@ class Authenticator:
                ):
                    raise AuthenticationError(
                        HTTPStatus.UNAUTHORIZED,
-                        "Destination mismatch in auth header",
+                        f"Destination mismatch in auth header, received: {destination!r}",
                        Codes.UNAUTHORIZED,
                    )
        if (
--- a/synapse/federation/transport/server/federation.py
+++ b/synapse/federation/transport/server/federation.py
@@ -509,6 +509,9 @@ class FederationV2InviteServlet(BaseFederationServerServlet):
        event = content["event"]
        invite_room_state = content.get("invite_room_state", [])

+        if not isinstance(invite_room_state, list):
+            invite_room_state = []
+
        # Synapse expects invite_room_state to be in unsigned, as it is in v1
        # API

--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -73,6 +73,8 @@ class AdminHandler:
            self._redact_all_events, REDACT_ALL_EVENTS_ACTION_NAME
        )

+        self.hs = hs
+
    async def get_redact_task(self, redact_id: str) -> Optional[ScheduledTask]:
        """Get the current status of an active redaction process

@@ -122,6 +124,7 @@ class AdminHandler:
            "consent_ts": user_info.consent_ts,
            "user_type": user_info.user_type,
            "is_guest": user_info.is_guest,
+            "suspended": user_info.suspended,
        }

        if self._msc3866_enabled:
@@ -423,8 +426,10 @@ class AdminHandler:
        user_id = task.params.get("user_id")
        assert user_id is not None

+        # puppet the user if they're ours, otherwise use admin to redact
        requester = create_requester(
-            user_id, authenticated_entity=admin.user.to_string()
+            user_id if self.hs.is_mine_id(user_id) else admin.user.to_string(),
+            authenticated_entity=admin.user.to_string(),
        )

        reason = task.params.get("reason")
@@ -443,8 +448,8 @@ class AdminHandler:
                ["m.room.member", "m.room.message"],
            )
            if not event_ids:
-                # there's nothing to redact
-                return TaskStatus.COMPLETE, result, None
+                # nothing to redact in this room
+                continue

            events = await self._store.get_events_as_list(event_ids)
            for event in events:
@@ -468,7 +473,7 @@ class AdminHandler:
                    "type": EventTypes.Redaction,
                    "content": {"reason": reason} if reason else {},
                    "room_id": room,
-                    "sender": user_id,
+                    "sender": requester.user.to_string(),
                }
                if room_version.updated_redaction_rules:
                    event_dict["content"]["redacts"] = event.event_id
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -896,10 +896,10 @@ class ApplicationServicesHandler:
        results = await make_deferred_yieldable(
            defer.DeferredList(
                [
-                    run_in_background(
+                    run_in_background(  # type: ignore[call-overload]
                        self.appservice_api.claim_client_keys,
                        # We know this must be an app service.
-                        self.store.get_app_service_by_id(service_id),  # type: ignore[arg-type]
+                        self.store.get_app_service_by_id(service_id),
                        service_query,
                    )
                    for service_id, service_query in query_by_appservice.items()
@@ -952,10 +952,10 @@ class ApplicationServicesHandler:
        results = await make_deferred_yieldable(
            defer.DeferredList(
                [
-                    run_in_background(
+                    run_in_background(  # type: ignore[call-overload]
                        self.appservice_api.query_keys,
                        # We know this must be an app service.
-                        self.store.get_app_service_by_id(service_id),  # type: ignore[arg-type]
+                        self.store.get_app_service_by_id(service_id),
                        service_query,
                    )
                    for service_id, service_query in query_by_appservice.items()
--- a/synapse/handlers/delayed_events.py
+++ b/synapse/handlers/delayed_events.py
@@ -1,3 +1,17 @@
+#
+# This file is licensed under the Affero General Public License (AGPL) version 3.
+#
+# Copyright (C) 2024 New Vector, Ltd
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# See the GNU Affero General Public License for more details:
+# <https://www.gnu.org/licenses/agpl-3.0.html>.
+#
+
 import logging
 from typing import TYPE_CHECKING, List, Optional, Set, Tuple

--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -48,6 +48,7 @@ from synapse.metrics.background_process_metrics import (
    wrap_as_background_process,
 )
 from synapse.storage.databases.main.client_ips import DeviceLastConnectionInfo
+from synapse.storage.databases.main.roommember import EventIdMembership
 from synapse.storage.databases.main.state_deltas import StateDelta
 from synapse.types import (
    DeviceListUpdates,
@@ -222,7 +223,6 @@ class DeviceWorkerHandler:
        return changed

    @trace
-    @measure_func("device.get_user_ids_changed")
    @cancellable
    async def get_user_ids_changed(
        self, user_id: str, from_token: StreamToken
@@ -290,9 +290,11 @@ class DeviceWorkerHandler:
                memberships_to_fetch.add(delta.prev_event_id)

        # Fetch all the memberships for the membership events
-        event_id_to_memberships = await self.store.get_membership_from_event_ids(
-            memberships_to_fetch
-        )
+        event_id_to_memberships: Mapping[str, Optional[EventIdMembership]] = {}
+        if memberships_to_fetch:
+            event_id_to_memberships = await self.store.get_membership_from_event_ids(
+                memberships_to_fetch
+            )

        joined_invited_knocked = (
            Membership.JOIN,
@@ -349,7 +351,6 @@ class DeviceWorkerHandler:

        return device_list_updates

-    @measure_func("_generate_sync_entry_for_device_list")
    async def generate_sync_entry_for_device_list(
        self,
        user_id: str,
@@ -728,6 +729,40 @@ class DeviceHandler(DeviceWorkerHandler):

        await self.notify_device_update(user_id, device_ids)

+    async def upsert_device(
+        self, user_id: str, device_id: str, display_name: Optional[str] = None
+    ) -> bool:
+        """Create or update a device
+
+        Args:
+            user_id: The user to update devices of.
+            device_id: The device to update.
+            display_name: The new display name for this device.
+
+        Returns:
+            True if the device was created, False if it was updated.
+
+        """
+
+        # Reject a new displayname which is too long.
+        self._check_device_name_length(display_name)
+
+        created = await self.store.store_device(
+            user_id,
+            device_id,
+            initial_device_display_name=display_name,
+        )
+
+        if not created:
+            await self.store.update_device(
+                user_id,
+                device_id,
+                new_display_name=display_name,
+            )
+
+        await self.notify_device_update(user_id, [device_id])
+        return created
+
    async def update_device(self, user_id: str, device_id: str, content: dict) -> None:
        """Update the given device

--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -39,6 +39,8 @@ from synapse.replication.http.devices import ReplicationUploadKeysForUserRestSer
 from synapse.types import (
    JsonDict,
    JsonMapping,
+    ScheduledTask,
+    TaskStatus,
    UserID,
    get_domain_from_id,
    get_verify_key_from_cross_signing_key,
@@ -70,6 +72,7 @@ class E2eKeysHandler:
        self.is_mine = hs.is_mine
        self.clock = hs.get_clock()
        self._worker_lock_handler = hs.get_worker_locks_handler()
+        self._task_scheduler = hs.get_task_scheduler()

        federation_registry = hs.get_federation_registry()

@@ -116,6 +119,10 @@ class E2eKeysHandler:
            hs.config.experimental.msc3984_appservice_key_query
        )

+        self._task_scheduler.register_action(
+            self._delete_old_one_time_keys_task, "delete_old_otks"
+        )
+
    @trace
    @cancellable
    async def query_devices(
@@ -615,7 +622,7 @@ class E2eKeysHandler:
        3. Attempt to fetch fallback keys from the database.

        Args:
-            local_query: An iterable of tuples of (user ID, device ID, algorithm).
+            local_query: An iterable of tuples of (user ID, device ID, algorithm, number of keys).
            always_include_fallback_keys: True to always include fallback keys.

        Returns:
@@ -1574,6 +1581,45 @@ class E2eKeysHandler:
                    return True
        return False

+    async def _delete_old_one_time_keys_task(
+        self, task: ScheduledTask
+    ) -> Tuple[TaskStatus, Optional[JsonMapping], Optional[str]]:
+        """Scheduler task to delete old one time keys.
+
+        Until Synapse 1.119, Synapse used to issue one-time-keys in a random order, leading to the possibility
+        that it could still have old OTKs that the client has dropped. This task is scheduled exactly once
+        by a database schema delta file, and it clears out old one-time-keys that look like they came from libolm.
+        """
+        last_user = task.result.get("from_user", "") if task.result else ""
+        while True:
+            # We process users in batches of 100
+            users, rowcount = await self.store.delete_old_otks_for_next_user_batch(
+                last_user, 100
+            )
+            if len(users) == 0:
+                # We're done!
+                return TaskStatus.COMPLETE, None, None
+
+            logger.debug(
+                "Deleted %i old one-time-keys for users '%s'..'%s'",
+                rowcount,
+                users[0],
+                users[-1],
+            )
+            last_user = users[-1]
+
+            # Store our progress
+            await self._task_scheduler.update_task(
+                task.id, result={"from_user": last_user}
+            )
+
+            # Sleep a little before doing the next user.
+            #
+            # matrix.org has about 15M users in the e2e_one_time_keys_json table
+            # (comprising 20M devices). We want this to take about a week, so we need
+            # to do about one batch of 100 users every 4 seconds.
+            await self.clock.sleep(4)
+

 def _check_cross_signing_key(
    key: JsonDict, user_id: str, key_type: str, signing_key: Optional[VerifyKey] = None
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -880,6 +880,9 @@ class FederationHandler:
        if stripped_room_state is None:
            raise KeyError("Missing 'knock_room_state' field in send_knock response")

+        if not isinstance(stripped_room_state, list):
+            raise TypeError("'knock_room_state' has wrong type")
+
        event.unsigned["knock_room_state"] = stripped_room_state

        context = EventContext.for_outlier(self._storage_controllers)
--- a/synapse/handlers/jwt.py
+++ b/synapse/handlers/jwt.py
@@ -18,7 +18,7 @@
 # [This file includes modifications made by New Vector Limited]
 #
 #
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional, Tuple

 from authlib.jose import JsonWebToken, JWTClaims
 from authlib.jose.errors import BadSignatureError, InvalidClaimError, JoseError
@@ -36,11 +36,12 @@ class JwtHandler:

        self.jwt_secret = hs.config.jwt.jwt_secret
        self.jwt_subject_claim = hs.config.jwt.jwt_subject_claim
+        self.jwt_display_name_claim = hs.config.jwt.jwt_display_name_claim
        self.jwt_algorithm = hs.config.jwt.jwt_algorithm
        self.jwt_issuer = hs.config.jwt.jwt_issuer
        self.jwt_audiences = hs.config.jwt.jwt_audiences

-    def validate_login(self, login_submission: JsonDict) -> str:
+    def validate_login(self, login_submission: JsonDict) -> Tuple[str, Optional[str]]:
        """
        Authenticates the user for the /login API

@@ -49,7 +50,8 @@ class JwtHandler:
                (including 'type' and other relevant fields)

        Returns:
-            The user ID that is logging in.
+            A tuple of (user_id, display_name) of the user that is logging in.
+            If the JWT does not contain a display name, the second element of the tuple will be None.

        Raises:
            LoginError if there was an authentication problem.
@@ -109,4 +111,10 @@ class JwtHandler:
        if user is None:
            raise LoginError(403, "Invalid JWT", errcode=Codes.FORBIDDEN)

-        return UserID(user, self.hs.hostname).to_string()
+        default_display_name = None
+        if self.jwt_display_name_claim:
+            display_name_claim = claims.get(self.jwt_display_name_claim)
+            if display_name_claim is not None:
+                default_display_name = display_name_claim
+
+        return UserID(user, self.hs.hostname).to_string(), default_display_name
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -196,7 +196,9 @@ class MessageHandler:
            AuthError (403) if the user doesn't have permission to view
            members of this room.
        """
-        state_filter = state_filter or StateFilter.all()
+        if state_filter is None:
+            state_filter = StateFilter.all()
+
        user_id = requester.user.to_string()

        if at_token:
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -22,6 +22,7 @@ import logging
 import random
 from typing import TYPE_CHECKING, List, Optional, Union

+from synapse.api.constants import ProfileFields
 from synapse.api.errors import (
    AuthError,
    Codes,
@@ -83,7 +84,7 @@ class ProfileHandler:

        Returns:
            A JSON dictionary. For local queries this will include the displayname and avatar_url
-            fields. For remote queries it may contain arbitrary information.
+            fields, if set. For remote queries it may contain arbitrary information.
        """
        target_user = UserID.from_string(user_id)

@@ -92,10 +93,13 @@ class ProfileHandler:
            if profileinfo.display_name is None and profileinfo.avatar_url is None:
                raise SynapseError(404, "Profile was not found", Codes.NOT_FOUND)

-            return {
-                "displayname": profileinfo.display_name,
-                "avatar_url": profileinfo.avatar_url,
-            }
+            # Do not include display name or avatar if unset.
+            ret = {}
+            if profileinfo.display_name is not None:
+                ret[ProfileFields.DISPLAYNAME] = profileinfo.display_name
+            if profileinfo.avatar_url is not None:
+                ret[ProfileFields.AVATAR_URL] = profileinfo.avatar_url
+            return ret
        else:
            try:
                result = await self.federation.make_query(
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -630,7 +630,9 @@ class RegistrationHandler:
        """
        await self._auto_join_rooms(user_id)

-    async def appservice_register(self, user_localpart: str, as_token: str) -> str:
+    async def appservice_register(
+        self, user_localpart: str, as_token: str
+    ) -> Tuple[str, ApplicationService]:
        user = UserID(user_localpart, self.hs.hostname)
        user_id = user.to_string()
        service = self.store.get_app_service_by_token(as_token)
@@ -653,7 +655,7 @@ class RegistrationHandler:
            appservice_id=service_id,
            create_profile_with_displayname=user.localpart,
        )
-        return user_id
+        return (user_id, service)

    def check_user_id_not_appservice_exclusive(
        self, user_id: str, allowed_appservice: Optional[ApplicationService] = None
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -1190,6 +1190,26 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
            origin_server_ts=origin_server_ts,
        )

+    async def check_for_any_membership_in_room(
+        self, *, user_id: str, room_id: str
+    ) -> None:
+        """
+        Check if the user has any membership in the room and raise error if not.
+
+        Args:
+            user_id: The user to check.
+            room_id: The room to check.
+
+        Raises:
+            AuthError if the user doesn't have any membership in the room.
+        """
+        result = await self.store.get_local_current_membership_for_user_in_room(
+            user_id=user_id, room_id=room_id
+        )
+
+        if result is None or result == (None, None):
+            raise AuthError(403, f"User {user_id} has no membership in room {room_id}")
+
    async def _should_perform_remote_join(
        self,
        user_id: str,
--- a/synapse/handlers/send_email.py
+++ b/synapse/handlers/send_email.py
@@ -47,15 +47,45 @@ logger = logging.getLogger(__name__)
 _is_old_twisted = parse_version(twisted.__version__) < parse_version("21")


-class _NoTLSESMTPSender(ESMTPSender):
-    """Extend ESMTPSender to disable TLS
+class _BackportESMTPSender(ESMTPSender):
+    """Extend old versions of ESMTPSender to configure TLS.

-    Unfortunately, before Twisted 21.2, ESMTPSender doesn't give an easy way to disable
-    TLS, so we override its internal method which it uses to generate a context factory.
+    Unfortunately, before Twisted 21.2, ESMTPSender doesn't give an easy way to
+    disable TLS, or to configure the hostname used for TLS certificate validation.
+    This backports the `hostname` parameter for that functionality.
    """

+    __hostname: Optional[str]
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        """"""
+        self.__hostname = kwargs.pop("hostname", None)
+        super().__init__(*args, **kwargs)
+
    def _getContextFactory(self) -> Optional[IOpenSSLContextFactory]:
-        return None
+        if self.context is not None:
+            return self.context
+        elif self.__hostname is None:
+            return None  # disable TLS if hostname is None
+        return optionsForClientTLS(self.__hostname)
+
+
+class _BackportESMTPSenderFactory(ESMTPSenderFactory):
+    """An ESMTPSenderFactory for _BackportESMTPSender.
+
+    This backports the `hostname` parameter, to disable or configure TLS.
+    """
+
+    __hostname: Optional[str]
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        self.__hostname = kwargs.pop("hostname", None)
+        super().__init__(*args, **kwargs)
+
+    def protocol(self, *args: Any, **kwargs: Any) -> ESMTPSender:  # type: ignore
+        # this overrides ESMTPSenderFactory's `protocol` attribute, with a Callable
+        # instantiating our _BackportESMTPSender, providing the hostname parameter
+        return _BackportESMTPSender(*args, **kwargs, hostname=self.__hostname)


 async def _sendmail(
@@ -71,6 +101,7 @@ async def _sendmail(
    require_tls: bool = False,
    enable_tls: bool = True,
    force_tls: bool = False,
+    tlsname: Optional[str] = None,
 ) -> None:
    """A simple wrapper around ESMTPSenderFactory, to allow substitution in tests

@@ -88,39 +119,33 @@ async def _sendmail(
        enable_tls: True to enable STARTTLS. If this is False and require_tls is True,
           the request will fail.
        force_tls: True to enable Implicit TLS.
+        tlsname: the domain name expected as the TLS certificate's commonname,
+           defaults to smtphost.
    """
    msg = BytesIO(msg_bytes)
    d: "Deferred[object]" = Deferred()
+    if not enable_tls:
+        tlsname = None
+    elif tlsname is None:
+        tlsname = smtphost

-    def build_sender_factory(**kwargs: Any) -> ESMTPSenderFactory:
-        return ESMTPSenderFactory(
-            username,
-            password,
-            from_addr,
-            to_addr,
-            msg,
-            d,
-            heloFallback=True,
-            requireAuthentication=require_auth,
-            requireTransportSecurity=require_tls,
-            **kwargs,
-        )
-
-    factory: IProtocolFactory
-    if _is_old_twisted:
-        # before twisted 21.2, we have to override the ESMTPSender protocol to disable
-        # TLS
-        factory = build_sender_factory()
-
-        if not enable_tls:
-            factory.protocol = _NoTLSESMTPSender
-    else:
-        # for twisted 21.2 and later, there is a 'hostname' parameter which we should
-        # set to enable TLS.
-        factory = build_sender_factory(hostname=smtphost if enable_tls else None)
+    factory: IProtocolFactory = (
+        _BackportESMTPSenderFactory if _is_old_twisted else ESMTPSenderFactory
+    )(
+        username,
+        password,
+        from_addr,
+        to_addr,
+        msg,
+        d,
+        heloFallback=True,
+        requireAuthentication=require_auth,
+        requireTransportSecurity=require_tls,
+        hostname=tlsname,
+    )

    if force_tls:
-        factory = TLSMemoryBIOFactory(optionsForClientTLS(smtphost), True, factory)
+        factory = TLSMemoryBIOFactory(optionsForClientTLS(tlsname), True, factory)

    endpoint = HostnameEndpoint(
        reactor, smtphost, smtpport, timeout=30, bindAddress=None
@@ -148,6 +173,7 @@ class SendEmailHandler:
        self._require_transport_security = hs.config.email.require_transport_security
        self._enable_tls = hs.config.email.enable_smtp_tls
        self._force_tls = hs.config.email.force_tls
+        self._tlsname = hs.config.email.email_tlsname

        self._sendmail = _sendmail

@@ -227,4 +253,5 @@ class SendEmailHandler:
            require_tls=self._require_transport_security,
            enable_tls=self._enable_tls,
            force_tls=self._force_tls,
+            tlsname=self._tlsname,
        )
--- a/synapse/handlers/sliding_sync/init.py
+++ b/synapse/handlers/sliding_sync/init.py
@@ -12,9 +12,10 @@
 # <https://www.gnu.org/licenses/agpl-3.0.html>.
 #

+import itertools
 import logging
 from itertools import chain
-from typing import TYPE_CHECKING, Dict, List, Mapping, Optional, Set, Tuple
+from typing import TYPE_CHECKING, AbstractSet, Dict, List, Mapping, Optional, Set, Tuple

 from prometheus_client import Histogram
 from typing_extensions import assert_never
@@ -38,6 +39,7 @@ from synapse.logging.opentracing import (
    trace,
 )
 from synapse.storage.databases.main.roommember import extract_heroes_from_room_summary
+from synapse.storage.databases.main.state_deltas import StateDelta
 from synapse.storage.databases.main.stream import PaginateFunction
 from synapse.storage.roommember import (
    MemberSummary,
@@ -47,8 +49,10 @@ from synapse.types import (
    MutableStateMap,
    PersistedEventPosition,
    Requester,
+    RoomStreamToken,
    SlidingSyncStreamToken,
    StateMap,
+    StrCollection,
    StreamKeyType,
    StreamToken,
 )
@@ -78,6 +82,15 @@ sync_processing_time = Histogram(
    ["initial"],
 )

+# Limit the number of state_keys we should remember sending down the connection for each
+# (room_id, user_id). We don't want to store and pull out too much data in the database.
+#
+# 100 is an arbitrary but small-ish number. The idea is that we probably won't send down
+# too many redundant member state events (that the client already knows about) for a
+# given ongoing conversation if we keep 100 around. Most rooms don't have 100 members
+# anyway and it takes a while to cycle through 100 members.
+MAX_NUMBER_PREVIOUS_STATE_KEYS_TO_REMEMBER = 100
+

 class SlidingSyncHandler:
    def __init__(self, hs: "HomeServer"):
@@ -293,7 +306,6 @@ class SlidingSyncHandler:
            # to record rooms as having updates even if there might not actually
            # be anything new for the user (e.g. due to event filters, events
            # having happened after the user left, etc).
-            unsent_room_ids = []
            if from_token:
                # The set of rooms that the client (may) care about, but aren't
                # in any list range (or subscribed to).
@@ -305,15 +317,24 @@ class SlidingSyncHandler:
                # TODO: Replace this with something faster. When we land the
                # sliding sync tables that record the most recent event
                # positions we can use that.
-                missing_event_map_by_room = (
-                    await self.store.get_room_events_stream_for_rooms(
-                        room_ids=missing_rooms,
-                        from_key=to_token.room_key,
-                        to_key=from_token.stream_token.room_key,
-                        limit=1,
+                unsent_room_ids: StrCollection
+                if await self.store.have_finished_sliding_sync_background_jobs():
+                    unsent_room_ids = await (
+                        self.store.get_rooms_that_have_updates_since_sliding_sync_table(
+                            room_ids=missing_rooms,
+                            from_key=from_token.stream_token.room_key,
+                        )
                    )
-                )
-                unsent_room_ids = list(missing_event_map_by_room)
+                else:
+                    missing_event_map_by_room = (
+                        await self.store.get_room_events_stream_for_rooms(
+                            room_ids=missing_rooms,
+                            from_key=to_token.room_key,
+                            to_key=from_token.stream_token.room_key,
+                            limit=1,
+                        )
+                    )
+                    unsent_room_ids = list(missing_event_map_by_room)

                new_connection_state.rooms.record_unsent_rooms(
                    unsent_room_ids, from_token.stream_token.room_key
@@ -443,16 +464,72 @@ class SlidingSyncHandler:
            to_token=to_token,
        )

-        event_map = await self.store.get_events(list(state_ids.values()))
+        events = await self.store.get_events_as_list(list(state_ids.values()))

        state_map = {}
-        for key, event_id in state_ids.items():
-            event = event_map.get(event_id)
-            if event:
-                state_map[key] = event
+        for event in events:
+            state_map[(event.type, event.state_key)] = event

        return state_map

+    @trace
+    async def get_current_state_deltas_for_room(
+        self,
+        room_id: str,
+        room_membership_for_user_at_to_token: RoomsForUserType,
+        from_token: RoomStreamToken,
+        to_token: RoomStreamToken,
+    ) -> List[StateDelta]:
+        """
+        Get the state deltas between two tokens taking into account the user's
+        membership. If the user is LEAVE/BAN, we will only get the state deltas up to
+        their LEAVE/BAN event (inclusive).
+
+        (> `from_token` and <= `to_token`)
+        """
+        membership = room_membership_for_user_at_to_token.membership
+        # We don't know how to handle `membership` values other than these. The
+        # code below would need to be updated.
+        assert membership in (
+            Membership.JOIN,
+            Membership.INVITE,
+            Membership.KNOCK,
+            Membership.LEAVE,
+            Membership.BAN,
+        )
+
+        # People shouldn't see past their leave/ban event
+        if membership in (
+            Membership.LEAVE,
+            Membership.BAN,
+        ):
+            to_bound = (
+                room_membership_for_user_at_to_token.event_pos.to_room_stream_token()
+            )
+        # If we are participating in the room, we can get the latest current state in
+        # the room
+        elif membership == Membership.JOIN:
+            to_bound = to_token
+        # We can only rely on the stripped state included in the invite/knock event
+        # itself so there will never be any state deltas to send down.
+        elif membership in (Membership.INVITE, Membership.KNOCK):
+            return []
+        else:
+            # We don't know how to handle this type of membership yet
+            #
+            # FIXME: We should use `assert_never` here but for some reason
+            # the exhaustive matching doesn't recognize the `Never` here.
+            # assert_never(membership)
+            raise AssertionError(
+                f"Unexpected membership {membership} that we don't know how to handle yet"
+            )
+
+        return await self.store.get_current_state_deltas_for_room(
+            room_id=room_id,
+            from_token=from_token,
+            to_token=to_bound,
+        )
+
    @trace
    async def get_room_sync_data(
        self,
@@ -513,6 +590,8 @@ class SlidingSyncHandler:

            state_reset_out_of_room = True

+        prev_room_sync_config = previous_connection_state.room_configs.get(room_id)
+
        # Determine whether we should limit the timeline to the token range.
        #
        # We should return historical messages (before token range) in the
@@ -541,7 +620,6 @@ class SlidingSyncHandler:
        # or `limited` mean for clients that interpret them correctly. In future this
        # behavior is almost certainly going to change.
        #
-        # TODO: Also handle changes to `required_state`
        from_bound = None
        initial = True
        ignore_timeline_bound = False
@@ -562,7 +640,6 @@ class SlidingSyncHandler:

            log_kv({"sliding_sync.room_status": room_status})

-            prev_room_sync_config = previous_connection_state.room_configs.get(room_id)
            if prev_room_sync_config is not None:
                # Check if the timeline limit has increased, if so ignore the
                # timeline bound and record the change (see "XXX: Odd behavior"
@@ -573,8 +650,6 @@ class SlidingSyncHandler:
                ):
                    ignore_timeline_bound = True

-                # TODO: Check for changes in `required_state``
-
        log_kv(
            {
                "sliding_sync.from_bound": from_bound,
@@ -740,13 +815,19 @@ class SlidingSyncHandler:

            stripped_state = []
            if invite_or_knock_event.membership == Membership.INVITE:
-                stripped_state.extend(
-                    invite_or_knock_event.unsigned.get("invite_room_state", [])
+                invite_state = invite_or_knock_event.unsigned.get(
+                    "invite_room_state", []
                )
+                if not isinstance(invite_state, list):
+                    invite_state = []
+
+                stripped_state.extend(invite_state)
            elif invite_or_knock_event.membership == Membership.KNOCK:
-                stripped_state.extend(
-                    invite_or_knock_event.unsigned.get("knock_room_state", [])
-                )
+                knock_state = invite_or_knock_event.unsigned.get("knock_room_state", [])
+                if not isinstance(knock_state, list):
+                    knock_state = []
+
+                stripped_state.extend(knock_state)

            stripped_state.append(strip_event(invite_or_knock_event))

@@ -775,8 +856,9 @@ class SlidingSyncHandler:
            # TODO: Limit the number of state events we're about to send down
            # the room, if its too many we should change this to an
            # `initial=True`?
-            deltas = await self.store.get_current_state_deltas_for_room(
+            deltas = await self.get_current_state_deltas_for_room(
                room_id=room_id,
+                room_membership_for_user_at_to_token=room_membership_for_user_at_to_token,
                from_token=from_bound,
                to_token=to_token.room_key,
            )
@@ -868,6 +950,14 @@ class SlidingSyncHandler:
        #
        # Calculate the `StateFilter` based on the `required_state` for the room
        required_state_filter = StateFilter.none()
+        # The requested `required_state_map` with the lazy membership expanded and
+        # `$ME` replaced with the user's ID. This allows us to see what membership we've
+        # sent down to the client in the next request.
+        #
+        # Make a copy so we can modify it. Still need to be careful to make a copy of
+        # the state key sets if we want to add/remove from them. We could make a deep
+        # copy but this saves us some work.
+        expanded_required_state_map = dict(room_sync_config.required_state_map)
        if room_membership_for_user_at_to_token.membership not in (
            Membership.INVITE,
            Membership.KNOCK,
@@ -932,22 +1022,55 @@ class SlidingSyncHandler:
                            and state_key == StateValues.LAZY
                        ):
                            lazy_load_room_members = True
+
                            # Everyone in the timeline is relevant
                            timeline_membership: Set[str] = set()
                            if timeline_events is not None:
                                for timeline_event in timeline_events:
+                                    # Anyone who sent a message is relevant
                                    timeline_membership.add(timeline_event.sender)

+                                    # We also care about invite, ban, kick, targets,
+                                    # etc.
+                                    if timeline_event.type == EventTypes.Member:
+                                        timeline_membership.add(
+                                            timeline_event.state_key
+                                        )
+
+                            # Update the required state filter so we pick up the new
+                            # membership
                            for user_id in timeline_membership:
                                required_state_types.append(
                                    (EventTypes.Member, user_id)
                                )

-                            # FIXME: We probably also care about invite, ban, kick, targets, etc
-                            # but the spec only mentions "senders".
+                            # Add an explicit entry for each user in the timeline
+                            #
+                            # Make a new set or copy of the state key set so we can
+                            # modify it without affecting the original
+                            # `required_state_map`
+                            expanded_required_state_map[EventTypes.Member] = (
+                                expanded_required_state_map.get(
+                                    EventTypes.Member, set()
+                                )
+                                | timeline_membership
+                            )
                        elif state_key == StateValues.ME:
                            num_others += 1
                            required_state_types.append((state_type, user.to_string()))
+                            # Replace `$ME` with the user's ID so we can deduplicate
+                            # when someone requests the same state with `$ME` or with
+                            # their user ID.
+                            #
+                            # Make a new set or copy of the state key set so we can
+                            # modify it without affecting the original
+                            # `required_state_map`
+                            expanded_required_state_map[EventTypes.Member] = (
+                                expanded_required_state_map.get(
+                                    EventTypes.Member, set()
+                                )
+                                | {user.to_string()}
+                            )
                        else:
                            num_others += 1
                            required_state_types.append((state_type, state_key))
@@ -988,6 +1111,10 @@ class SlidingSyncHandler:
                include_others=required_state_filter.include_others,
            )

+        # The required state map to store in the room sync config, if it has
+        # changed.
+        changed_required_state_map: Optional[Mapping[str, AbstractSet[str]]] = None
+
        # We can return all of the state that was requested if this was the first
        # time we've sent the room down this connection.
        room_state: StateMap[EventBase] = {}
@@ -1001,6 +1128,29 @@ class SlidingSyncHandler:
        else:
            assert from_bound is not None

+            if prev_room_sync_config is not None:
+                # Check if there are any changes to the required state config
+                # that we need to handle.
+                changed_required_state_map, added_state_filter = (
+                    _required_state_changes(
+                        user.to_string(),
+                        prev_required_state_map=prev_room_sync_config.required_state_map,
+                        request_required_state_map=expanded_required_state_map,
+                        state_deltas=room_state_delta_id_map,
+                    )
+                )
+
+                if added_state_filter:
+                    # Some state entries got added, so we pull out the current
+                    # state for them. If we don't do this we'd only send down new deltas.
+                    state_ids = await self.get_current_state_ids_at(
+                        room_id=room_id,
+                        room_membership_for_user_at_to_token=room_membership_for_user_at_to_token,
+                        state_filter=added_state_filter,
+                        to_token=to_token,
+                    )
+                    room_state_delta_id_map.update(state_ids)
+
            events = await self.store.get_events(
                state_filter.filter_state(room_state_delta_id_map).values()
            )
@@ -1048,22 +1198,42 @@ class SlidingSyncHandler:
                    )
                )

-        # Figure out the last bump event in the room
-        #
-        # By default, just choose the membership event position for any non-join membership
-        bump_stamp = room_membership_for_user_at_to_token.event_pos.stream
+        # Figure out the last bump event in the room. If the bump stamp hasn't
+        # changed we omit it from the response.
+        bump_stamp = None
+
+        always_return_bump_stamp = (
+            # We use the membership event position for any non-join
+            room_membership_for_user_at_to_token.membership != Membership.JOIN
+            # We didn't fetch any timeline events but we should still check for
+            # a bump_stamp that might be somewhere
+            or limited is None
+            # There might be a bump event somewhere before the timeline events
+            # that we fetched, that we didn't previously send down
+            or limited is True
+            # Always give the client some frame of reference if this is the
+            # first time they are seeing the room down the connection
+            or initial
+        )
+
        # If we're joined to the room, we need to find the last bump event before the
        # `to_token`
        if room_membership_for_user_at_to_token.membership == Membership.JOIN:
-            # Try and get a bump stamp, if not we just fall back to the
-            # membership token.
+            # Try and get a bump stamp
            new_bump_stamp = await self._get_bump_stamp(
-                room_id, to_token, timeline_events
+                room_id,
+                to_token,
+                timeline_events,
+                check_outside_timeline=always_return_bump_stamp,
            )
            if new_bump_stamp is not None:
                bump_stamp = new_bump_stamp

-        if bump_stamp < 0:
+        if bump_stamp is None and always_return_bump_stamp:
+            # By default, just choose the membership event position for any non-join membership
+            bump_stamp = room_membership_for_user_at_to_token.event_pos.stream
+
+        if bump_stamp is not None and bump_stamp < 0:
            # We never want to send down negative stream orderings, as you can't
            # sensibly compare positive and negative stream orderings (they have
            # different meanings).
@@ -1079,10 +1249,15 @@ class SlidingSyncHandler:
            # sensible order again.
            bump_stamp = 0

-        unstable_expanded_timeline = False
-        prev_room_sync_config = previous_connection_state.room_configs.get(room_id)
+        room_sync_required_state_map_to_persist: Mapping[str, AbstractSet[str]] = (
+            expanded_required_state_map
+        )
+        if changed_required_state_map:
+            room_sync_required_state_map_to_persist = changed_required_state_map
+
        # Record the `room_sync_config` if we're `ignore_timeline_bound` (which means
        # that the `timeline_limit` has increased)
+        unstable_expanded_timeline = False
        if ignore_timeline_bound:
            # FIXME: We signal the fact that we're sending down more events to
            # the client by setting `unstable_expanded_timeline` to true (see
@@ -1091,7 +1266,7 @@ class SlidingSyncHandler:

            new_connection_state.room_configs[room_id] = RoomSyncConfig(
                timeline_limit=room_sync_config.timeline_limit,
-                required_state_map=room_sync_config.required_state_map,
+                required_state_map=room_sync_required_state_map_to_persist,
            )
        elif prev_room_sync_config is not None:
            # If the result is `limited` then we need to record that the
@@ -1120,13 +1295,20 @@ class SlidingSyncHandler:
            ):
                new_connection_state.room_configs[room_id] = RoomSyncConfig(
                    timeline_limit=room_sync_config.timeline_limit,
-                    required_state_map=room_sync_config.required_state_map,
+                    required_state_map=room_sync_required_state_map_to_persist,
                )

-            # TODO: Record changes in required_state.
+            elif changed_required_state_map is not None:
+                new_connection_state.room_configs[room_id] = RoomSyncConfig(
+                    timeline_limit=room_sync_config.timeline_limit,
+                    required_state_map=room_sync_required_state_map_to_persist,
+                )

        else:
-            new_connection_state.room_configs[room_id] = room_sync_config
+            new_connection_state.room_configs[room_id] = RoomSyncConfig(
+                timeline_limit=room_sync_config.timeline_limit,
+                required_state_map=room_sync_required_state_map_to_persist,
+            )

        set_tag(SynapseTags.RESULT_PREFIX + "initial", initial)

@@ -1156,14 +1338,23 @@ class SlidingSyncHandler:

    @trace
    async def _get_bump_stamp(
-        self, room_id: str, to_token: StreamToken, timeline: List[EventBase]
+        self,
+        room_id: str,
+        to_token: StreamToken,
+        timeline: List[EventBase],
+        check_outside_timeline: bool,
    ) -> Optional[int]:
-        """Get a bump stamp for the room, if we have a bump event
+        """Get a bump stamp for the room, if we have a bump event and it has
+        changed.

        Args:
            room_id
            to_token: The upper bound of token to return
            timeline: The list of events we have fetched.
+            limited: If the timeline was limited.
+            check_outside_timeline: Whether we need to check for bump stamp for
+                events before the timeline if we didn't find a bump stamp in
+                the timeline events.
        """

        # First check the timeline events we're returning to see if one of
@@ -1183,6 +1374,11 @@ class SlidingSyncHandler:
                if new_bump_stamp > 0:
                    return new_bump_stamp

+        if not check_outside_timeline:
+            # If we are not a limited sync, then we know the bump stamp can't
+            # have changed.
+            return None
+
        # We can quickly query for the latest bump event in the room using the
        # sliding sync tables.
        latest_room_bump_stamp = await self.store.get_latest_bump_stamp_for_room(
@@ -1242,3 +1438,231 @@ class SlidingSyncHandler:
                    return new_bump_event_pos.stream

            return None
+
+
+def _required_state_changes(
+    user_id: str,
+    *,
+    prev_required_state_map: Mapping[str, AbstractSet[str]],
+    request_required_state_map: Mapping[str, AbstractSet[str]],
+    state_deltas: StateMap[str],
+) -> Tuple[Optional[Mapping[str, AbstractSet[str]]], StateFilter]:
+    """Calculates the changes between the required state room config from the
+    previous requests compared with the current request.
+
+    This does two things. First, it calculates if we need to update the room
+    config due to changes to required state. Secondly, it works out which state
+    entries we need to pull from current state and return due to the state entry
+    now appearing in the required state when it previously wasn't (on top of the
+    state deltas).
+
+    This function tries to ensure to handle the case where a state entry is
+    added, removed and then added again to the required state. In that case we
+    only want to re-send that entry down sync if it has changed.
+
+    Returns:
+        A 2-tuple of updated required state config (or None if there is no update)
+        and the state filter to use to fetch extra current state that we need to
+        return.
+    """
+    if prev_required_state_map == request_required_state_map:
+        # There has been no change. Return immediately.
+        return None, StateFilter.none()
+
+    prev_wildcard = prev_required_state_map.get(StateValues.WILDCARD, set())
+    request_wildcard = request_required_state_map.get(StateValues.WILDCARD, set())
+
+    # If we were previously fetching everything ("*", "*"), always update the effective
+    # room required state config to match the request. And since we we're previously
+    # already fetching everything, we don't have to fetch anything now that they've
+    # narrowed.
+    if StateValues.WILDCARD in prev_wildcard:
+        return request_required_state_map, StateFilter.none()
+
+    # If a event type wildcard has been added or removed we don't try and do
+    # anything fancy, and instead always update the effective room required
+    # state config to match the request.
+    if request_wildcard - prev_wildcard:
+        # Some keys were added, so we need to fetch everything
+        return request_required_state_map, StateFilter.all()
+    if prev_wildcard - request_wildcard:
+        # Keys were only removed, so we don't have to fetch everything.
+        return request_required_state_map, StateFilter.none()
+
+    # Contains updates to the required state map compared with the previous room
+    # config. This has the same format as `RoomSyncConfig.required_state`
+    changes: Dict[str, AbstractSet[str]] = {}
+
+    # The set of types/state keys that we need to fetch and return to the
+    # client. Passed to `StateFilter.from_types(...)`
+    added: List[Tuple[str, Optional[str]]] = []
+
+    # Convert the list of state deltas to map from type to state_keys that have
+    # changed.
+    changed_types_to_state_keys: Dict[str, Set[str]] = {}
+    for event_type, state_key in state_deltas:
+        changed_types_to_state_keys.setdefault(event_type, set()).add(state_key)
+
+    # First we calculate what, if anything, has been *added*.
+    for event_type in (
+        prev_required_state_map.keys() | request_required_state_map.keys()
+    ):
+        old_state_keys = prev_required_state_map.get(event_type, set())
+        request_state_keys = request_required_state_map.get(event_type, set())
+        changed_state_keys = changed_types_to_state_keys.get(event_type, set())
+
+        if old_state_keys == request_state_keys:
+            # No change to this type
+            continue
+
+        if not request_state_keys - old_state_keys:
+            # Nothing *added*, so we skip. Removals happen below.
+            continue
+
+        # We only remove state keys from the effective state if they've been
+        # removed from the request *and* the state has changed. This ensures
+        # that if a client removes and then re-adds a state key, we only send
+        # down the associated current state event if its changed (rather than
+        # sending down the same event twice).
+        invalidated_state_keys = (
+            old_state_keys - request_state_keys
+        ) & changed_state_keys
+
+        # Figure out which state keys we should remember sending down the connection
+        inheritable_previous_state_keys = (
+            # Retain the previous state_keys that we've sent down before.
+            # Wildcard and lazy state keys are not sticky from previous requests.
+            (old_state_keys - {StateValues.WILDCARD, StateValues.LAZY})
+            - invalidated_state_keys
+        )
+
+        # Always update changes to include the newly added keys (we've expanded the set
+        # of state keys), use the new requested set with whatever hasn't been
+        # invalidated from the previous set.
+        changes[event_type] = request_state_keys | inheritable_previous_state_keys
+        # Limit the number of state_keys we should remember sending down the connection
+        # for each (room_id, user_id). We don't want to store and pull out too much data
+        # in the database. This is a happy-medium between remembering nothing and
+        # everything. We can avoid sending redundant state down the connection most of
+        # the time given that most rooms don't have 100 members anyway and it takes a
+        # while to cycle through 100 members.
+        #
+        # Only remember up to (MAX_NUMBER_PREVIOUS_STATE_KEYS_TO_REMEMBER)
+        if len(changes[event_type]) > MAX_NUMBER_PREVIOUS_STATE_KEYS_TO_REMEMBER:
+            # Reset back to only the requested state keys
+            changes[event_type] = request_state_keys
+
+            # Skip if there isn't any room to fill in the rest with previous state keys
+            if len(request_state_keys) < MAX_NUMBER_PREVIOUS_STATE_KEYS_TO_REMEMBER:
+                # Fill the rest with previous state_keys. Ideally, we could sort
+                # these by recency but it's just a set so just pick an arbitrary
+                # subset (good enough).
+                changes[event_type] = changes[event_type] | set(
+                    itertools.islice(
+                        inheritable_previous_state_keys,
+                        # Just taking the difference isn't perfect as there could be
+                        # overlap in the keys between the requested and previous but we
+                        # will decide to just take the easy route for now and avoid
+                        # additional set operations to figure it out.
+                        MAX_NUMBER_PREVIOUS_STATE_KEYS_TO_REMEMBER
+                        - len(request_state_keys),
+                    )
+                )
+
+        if StateValues.WILDCARD in old_state_keys:
+            # We were previously fetching everything for this type, so we don't need to
+            # fetch anything new.
+            continue
+
+        # Record the new state keys to fetch for this type.
+        if StateValues.WILDCARD in request_state_keys:
+            # If we have added a wildcard then we always just fetch everything.
+            added.append((event_type, None))
+        else:
+            for state_key in request_state_keys - old_state_keys:
+                if state_key == StateValues.ME:
+                    added.append((event_type, user_id))
+                elif state_key == StateValues.LAZY:
+                    # We handle lazy loading separately (outside this function),
+                    # so don't need to explicitly add anything here.
+                    #
+                    # LAZY values should also be ignore for event types that are
+                    # not membership.
+                    pass
+                else:
+                    added.append((event_type, state_key))
+
+    added_state_filter = StateFilter.from_types(added)
+
+    # Figure out what changes we need to apply to the effective required state
+    # config.
+    for event_type, changed_state_keys in changed_types_to_state_keys.items():
+        old_state_keys = prev_required_state_map.get(event_type, set())
+        request_state_keys = request_required_state_map.get(event_type, set())
+
+        if old_state_keys == request_state_keys:
+            # No change.
+            continue
+
+        # If we see the `user_id` as a state_key, also add "$ME" to the list of state
+        # that has changed to account for people requesting `required_state` with `$ME`
+        # or their user ID.
+        if user_id in changed_state_keys:
+            changed_state_keys.add(StateValues.ME)
+
+        # We only remove state keys from the effective state if they've been
+        # removed from the request *and* the state has changed. This ensures
+        # that if a client removes and then re-adds a state key, we only send
+        # down the associated current state event if its changed (rather than
+        # sending down the same event twice).
+        invalidated_state_keys = (
+            old_state_keys - request_state_keys
+        ) & changed_state_keys
+
+        # We've expanded the set of state keys, ... (already handled above)
+        if request_state_keys - old_state_keys:
+            continue
+
+        old_state_key_wildcard = StateValues.WILDCARD in old_state_keys
+        request_state_key_wildcard = StateValues.WILDCARD in request_state_keys
+
+        if old_state_key_wildcard != request_state_key_wildcard:
+            # If a state_key wildcard has been added or removed, we always update the
+            # effective room required state config to match the request.
+            changes[event_type] = request_state_keys
+            continue
+
+        if event_type == EventTypes.Member:
+            old_state_key_lazy = StateValues.LAZY in old_state_keys
+            request_state_key_lazy = StateValues.LAZY in request_state_keys
+
+            if old_state_key_lazy != request_state_key_lazy:
+                # If a "$LAZY" has been added or removed we always update the effective room
+                # required state config to match the request.
+                changes[event_type] = request_state_keys
+                continue
+
+        # At this point there are no wildcards and no additions to the set of
+        # state keys requested, only deletions.
+        #
+        # We only remove state keys from the effective state if they've been
+        # removed from the request *and* the state has changed. This ensures
+        # that if a client removes and then re-adds a state key, we only send
+        # down the associated current state event if its changed (rather than
+        # sending down the same event twice).
+        if invalidated_state_keys:
+            changes[event_type] = old_state_keys - invalidated_state_keys
+
+    if changes:
+        # Update the required state config based on the changes.
+        new_required_state_map = dict(prev_required_state_map)
+        for event_type, state_keys in changes.items():
+            if state_keys:
+                new_required_state_map[event_type] = state_keys
+            else:
+                # Remove entries with empty state keys.
+                new_required_state_map.pop(event_type, None)
+
+        return new_required_state_map, added_state_filter
+    else:
+        return None, added_state_filter
--- a/synapse/handlers/sliding_sync/extensions.py
+++ b/synapse/handlers/sliding_sync/extensions.py
@@ -49,7 +49,10 @@ from synapse.types.handlers.sliding_sync import (
    SlidingSyncConfig,
    SlidingSyncResult,
 )
-from synapse.util.async_helpers import concurrently_execute
+from synapse.util.async_helpers import (
+    concurrently_execute,
+    gather_optional_coroutines,
+)

 if TYPE_CHECKING:
    from synapse.server import HomeServer
@@ -97,26 +100,26 @@ class SlidingSyncExtensionHandler:
        if sync_config.extensions is None:
            return SlidingSyncResult.Extensions()

-        to_device_response = None
+        to_device_coro = None
        if sync_config.extensions.to_device is not None:
-            to_device_response = await self.get_to_device_extension_response(
+            to_device_coro = self.get_to_device_extension_response(
                sync_config=sync_config,
                to_device_request=sync_config.extensions.to_device,
                to_token=to_token,
            )

-        e2ee_response = None
+        e2ee_coro = None
        if sync_config.extensions.e2ee is not None:
-            e2ee_response = await self.get_e2ee_extension_response(
+            e2ee_coro = self.get_e2ee_extension_response(
                sync_config=sync_config,
                e2ee_request=sync_config.extensions.e2ee,
                to_token=to_token,
                from_token=from_token,
            )

-        account_data_response = None
+        account_data_coro = None
        if sync_config.extensions.account_data is not None:
-            account_data_response = await self.get_account_data_extension_response(
+            account_data_coro = self.get_account_data_extension_response(
                sync_config=sync_config,
                previous_connection_state=previous_connection_state,
                new_connection_state=new_connection_state,
@@ -127,9 +130,9 @@ class SlidingSyncExtensionHandler:
                from_token=from_token,
            )

-        receipts_response = None
+        receipts_coro = None
        if sync_config.extensions.receipts is not None:
-            receipts_response = await self.get_receipts_extension_response(
+            receipts_coro = self.get_receipts_extension_response(
                sync_config=sync_config,
                previous_connection_state=previous_connection_state,
                new_connection_state=new_connection_state,
@@ -141,9 +144,9 @@ class SlidingSyncExtensionHandler:
                from_token=from_token,
            )

-        typing_response = None
+        typing_coro = None
        if sync_config.extensions.typing is not None:
-            typing_response = await self.get_typing_extension_response(
+            typing_coro = self.get_typing_extension_response(
                sync_config=sync_config,
                actual_lists=actual_lists,
                actual_room_ids=actual_room_ids,
@@ -153,6 +156,20 @@ class SlidingSyncExtensionHandler:
                from_token=from_token,
            )

+        (
+            to_device_response,
+            e2ee_response,
+            account_data_response,
+            receipts_response,
+            typing_response,
+        ) = await gather_optional_coroutines(
+            to_device_coro,
+            e2ee_coro,
+            account_data_coro,
+            receipts_coro,
+            typing_coro,
+        )
+
        return SlidingSyncResult.Extensions(
            to_device=to_device_response,
            e2ee=e2ee_response,
@@ -572,7 +589,8 @@ class SlidingSyncExtensionHandler:

            # Now record which rooms are now up to data, and which rooms have
            # pending updates to send.
-            new_connection_state.account_data.record_sent_rooms(relevant_room_ids)
+            new_connection_state.account_data.record_sent_rooms(previously_rooms.keys())
+            new_connection_state.account_data.record_sent_rooms(initial_rooms)
            missing_updates = (
                all_updates_since_the_from_token.keys() - relevant_room_ids
            )
@@ -763,9 +781,10 @@ class SlidingSyncExtensionHandler:

                room_id_to_receipt_map[room_id] = {"type": type, "content": content}

-        # Now we update the per-connection state to track which receipts we have
-        # and haven't sent down.
-        new_connection_state.receipts.record_sent_rooms(relevant_room_ids)
+            # Update the per-connection state to track which rooms we have sent
+            # all the receipts for.
+            new_connection_state.receipts.record_sent_rooms(previously_rooms.keys())
+            new_connection_state.receipts.record_sent_rooms(initial_rooms)

        if from_token:
            # Now find the set of rooms that may have receipts that we're not sending
--- a/synapse/handlers/sliding_sync/room_lists.py
+++ b/synapse/handlers/sliding_sync/room_lists.py
@@ -123,6 +123,19 @@ class SlidingSyncInterestedRooms:
    newly_left_rooms: AbstractSet[str]
    dm_room_ids: AbstractSet[str]

+    @staticmethod
+    def empty() -> "SlidingSyncInterestedRooms":
+        return SlidingSyncInterestedRooms(
+            lists={},
+            relevant_room_map={},
+            relevant_rooms_to_send_map={},
+            all_rooms=set(),
+            room_membership_for_user_map={},
+            newly_joined_rooms=set(),
+            newly_left_rooms=set(),
+            dm_room_ids=set(),
+        )
+

 def filter_membership_for_sync(
    *,
@@ -181,6 +194,14 @@ class SlidingSyncRoomLists:
        from_token: Optional[StreamToken],
    ) -> SlidingSyncInterestedRooms:
        """Fetch the set of rooms that match the request"""
+        has_lists = sync_config.lists is not None and len(sync_config.lists) > 0
+        has_room_subscriptions = (
+            sync_config.room_subscriptions is not None
+            and len(sync_config.room_subscriptions) > 0
+        )
+
+        if not has_lists and not has_room_subscriptions:
+            return SlidingSyncInterestedRooms.empty()

        if await self.store.have_finished_sliding_sync_background_jobs():
            return await self._compute_interested_rooms_new_tables(
@@ -479,6 +500,16 @@ class SlidingSyncRoomLists:
                # depending on the `required_state` requested (see below).
                partial_state_rooms = await self.store.get_partial_rooms()

+                # Fetch any rooms that we have not already fetched from the database.
+                subscription_sliding_sync_rooms = (
+                    await self.store.get_sliding_sync_room_for_user_batch(
+                        user_id,
+                        sync_config.room_subscriptions.keys()
+                        - room_membership_for_user_map.keys(),
+                    )
+                )
+                room_membership_for_user_map.update(subscription_sliding_sync_rooms)
+
                for (
                    room_id,
                    room_subscription,
@@ -486,17 +517,11 @@ class SlidingSyncRoomLists:
                    # Check if we have a membership for the room, but didn't pull it out
                    # above. This could be e.g. a leave that we don't pull out by
                    # default.
-                    current_room_entry = (
-                        await self.store.get_sliding_sync_room_for_user(
-                            user_id, room_id
-                        )
-                    )
+                    current_room_entry = room_membership_for_user_map.get(room_id)
                    if not current_room_entry:
                        # TODO: Handle rooms the user isn't in.
                        continue

-                    room_membership_for_user_map[room_id] = current_room_entry
-
                    all_rooms.add(room_id)

                    # Take the superset of the `RoomSyncConfig` for each room.
--- a/Show More
+++ b/Show More
				`@@ -1 +0,0 @@`
				`Remove spurious "TODO UPDATE ALL THIS" note in the Debian installation docs.`