diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5094e27..c2d53ea 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -47,6 +47,36 @@ jobs:
       - name: Run verification suite
         run: npm run verify
 
+  node20:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+
+      - name: Set up lowest supported Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '20.19.0'
+          cache: 'npm'
+          cache-dependency-path: |
+            package-lock.json
+            server/package-lock.json
+
+      - name: Install root dependencies
+        run: npm ci
+
+      - name: Install server dependencies
+        run: npm ci
+        working-directory: server
+
+      - name: Run unit and relay integration gates
+        run: |
+          npm run test:coverage
+          node scripts/test-server-routes.mjs
+          node scripts/test-server-ws.mjs
+        env:
+          ADMIN_METRICS_TOKEN: verify-admin-token-with-more-than-32-chars
+
   e2e:
     # Kept separate from `verify`: this job needs a downloaded browser, so a
     # failure here should read as "the browser flow broke", not as a broken
@@ -66,6 +96,10 @@ jobs:
       - name: Install root dependencies
         run: npm ci
 
+      - name: Install server dependencies
+        run: npm ci
+        working-directory: server
+
       - name: Install Playwright browsers
         run: npx playwright install --with-deps chromium chromium-headless-shell firefox webkit
 
@@ -75,3 +109,14 @@ jobs:
 
       - name: Run cross-browser detection and extension E2E tests
         run: npm run test:e2e
+
+      - name: Upload browser failure diagnostics
+        if: failure()
+        uses: actions/upload-artifact@v7
+        with:
+          name: e2e-failure-diagnostics
+          path: |
+            test-results/
+            playwright-report/
+          if-no-files-found: error
+          retention-days: 14
diff --git a/.github/workflows/race-tests.yml b/.github/workflows/race-tests.yml
index 7529a3b..8f14849 100644
--- a/.github/workflows/race-tests.yml
+++ b/.github/workflows/race-tests.yml
@@ -15,7 +15,7 @@ concurrency:
 jobs:
   extension-races:
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 60
     steps:
       - name: Checkout code
         uses: actions/checkout@v7
@@ -30,6 +30,10 @@ jobs:
       - name: Install dependencies
         run: npm ci
 
+      - name: Install server dependencies
+        run: npm ci
+        working-directory: server
+
       - name: Install Playwright Chromium
         run: npx playwright install --with-deps chromium chromium-headless-shell
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index f8f43a6..b627534 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -5,14 +5,139 @@ on:
     tags:
       - 'v*'
 
-# A release run must never be interrupted (it commits back to main and publishes
-# artifacts). Only dedupe accidental re-pushes of the same tag.
 concurrency:
   group: release-${{ github.ref_name }}
   cancel-in-progress: false
 
 jobs:
+  preflight:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      checks: read
+    outputs:
+      version: ${{ steps.release-ref.outputs.version }}
+      tag-commit: ${{ steps.release-ref.outputs.tag_commit }}
+    steps:
+      - name: Checkout release tag
+        uses: actions/checkout@v7
+        with:
+          fetch-depth: 0
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+          cache: 'npm'
+          cache-dependency-path: |
+            package-lock.json
+            server/package-lock.json
+
+      - name: Validate annotated tag, main commit, and required checks
+        id: release-ref
+        run: node scripts/release-preflight.mjs
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install root dependencies
+        run: npm ci
+
+      - name: Install server dependencies
+        run: npm ci
+        working-directory: server
+
+      - name: Run complete release verification
+        run: npm run verify
+
+      - name: Install Playwright browsers
+        run: npx playwright install --with-deps chromium chromium-headless-shell firefox webkit
+
+      - name: Run browser E2E suite
+        run: npm run test:e2e
+
+      - name: Build relay container without publishing
+        run: docker build --file server/Dockerfile --tag koalasync-release-preflight .
+
+      - name: Smoke-test relay container
+        run: |
+          CONTAINER_ID=$(docker run --detach --publish 127.0.0.1::3000 --env SERVER_SALT=release-preflight-salt-with-more-than-thirty-two-chars koalasync-release-preflight)
+          trap 'docker rm --force "$CONTAINER_ID" >/dev/null 2>&1 || true' EXIT
+          HOST_PORT=$(docker port "$CONTAINER_ID" 3000/tcp | sed 's/.*://')
+          for attempt in $(seq 1 30); do
+            if curl --fail --silent "http://127.0.0.1:$HOST_PORT/health" >/dev/null; then
+              exit 0
+            fi
+            sleep 1
+          done
+          docker logs "$CONTAINER_ID"
+          exit 1
+
+  release-extension-draft:
+    needs: preflight
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      id-token: write
+      attestations: write
+    steps:
+      - name: Checkout release tag
+        uses: actions/checkout@v7
+        with:
+          fetch-depth: 0
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+          cache: 'npm'
+
+      - name: Install dependencies and build release artifacts
+        run: |
+          npm ci
+          npm run build:extension
+          node website/build.cjs
+
+      - name: Validate Firefox package
+        run: npx addons-linter --warnings-as-errors dist/koalasync-firefox.zip
+
+      - name: Generate extension checksums
+        working-directory: dist
+        run: sha256sum koalasync-chrome.zip koalasync-firefox.zip > SHA256SUMS
+
+      - name: Validate release assets before publication
+        run: node scripts/verify-published-release.mjs "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY" --asset-dir dist --skip-attestation
+
+      - name: Attest extension archives
+        uses: actions/attest@v4
+        with:
+          subject-path: dist/koalasync-*.zip
+
+      - name: Create draft GitHub release
+        uses: softprops/action-gh-release@v3
+        with:
+          files: |
+            dist/koalasync-chrome.zip
+            dist/koalasync-firefox.zip
+            dist/SHA256SUMS
+          name: Release ${{ github.ref_name }}
+          generate_release_notes: true
+          draft: true
+          prerelease: false
+
+      - name: Verify draft extension release
+        run: node scripts/verify-published-release.mjs "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Upload website artifacts
+        uses: actions/upload-artifact@v7
+        with:
+          name: website-www
+          path: website/www/
+          if-no-files-found: error
+
   release-server:
+    needs: [preflight, release-extension-draft]
     runs-on: ubuntu-latest
     permissions:
       contents: read
@@ -20,7 +145,7 @@ jobs:
       id-token: write
       attestations: write
     steps:
-      - name: Checkout code
+      - name: Checkout release tag
         uses: actions/checkout@v7
 
       - name: Set up Docker Buildx
@@ -52,131 +177,46 @@ jobs:
           platforms: linux/amd64,linux/arm64
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          # Reuse layers across releases to speed up the multi-arch build.
           cache-from: type=gha
           cache-to: type=gha,mode=max
 
-      - name: Generate artifact attestation
+      - name: Attest relay image
         uses: actions/attest@v4
         with:
           subject-name: ghcr.io/${{ github.repository }}
           subject-digest: ${{ steps.build.outputs.digest }}
           push-to-registry: true
 
-  release-extension:
+      - name: Verify manifest, provenance, and running image
+        env:
+          DIGEST: ${{ steps.build.outputs.digest }}
+          IMAGE: ghcr.io/${{ github.repository }}
+          SOURCE_DIGEST: ${{ needs.preflight.outputs.tag-commit }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          docker buildx imagetools inspect "$IMAGE@$DIGEST" --raw > /tmp/koalasync-manifest.json
+          node -e 'const m=require("/tmp/koalasync-manifest.json"); const p=new Set(m.manifests.map(x=>`${x.platform.os}/${x.platform.architecture}`)); for (const x of ["linux/amd64","linux/arm64"]) if(!p.has(x)) throw new Error(`missing platform ${x}`)'
+          gh attestation verify "oci://$IMAGE@$DIGEST" --repo "$GITHUB_REPOSITORY" --signer-workflow "$GITHUB_REPOSITORY/.github/workflows/release.yml" --source-ref "$GITHUB_REF" --source-digest "$SOURCE_DIGEST" --deny-self-hosted-runners
+          docker pull --platform linux/amd64 "$IMAGE@$DIGEST"
+          CONTAINER_ID=$(docker run --detach --publish 127.0.0.1::3000 --env SERVER_SALT=release-smoke-salt-with-more-than-thirty-two-chars "$IMAGE@$DIGEST")
+          trap 'docker rm --force "$CONTAINER_ID" >/dev/null 2>&1 || true' EXIT
+          HOST_PORT=$(docker port "$CONTAINER_ID" 3000/tcp | sed 's/.*://')
+          for attempt in $(seq 1 30); do
+            if curl --fail --silent "http://127.0.0.1:$HOST_PORT/health" >/dev/null; then
+              exit 0
+            fi
+            sleep 1
+          done
+          docker logs "$CONTAINER_ID"
+          exit 1
+
+  finalize-release:
+    needs: [preflight, release-extension-draft, release-server]
     runs-on: ubuntu-latest
     permissions:
       contents: write
-      id-token: write
-      attestations: write
     steps:
-      - name: Checkout code
-        uses: actions/checkout@v7
-        with:
-          fetch-depth: 0
-
-      - name: Set up Node.js
-        uses: actions/setup-node@v6
-        with:
-          node-version: '24'
-          cache: 'npm'
-
-      - name: Extract version from tag
-        id: version
-        run: echo "VERSION=${GITHUB_REF_NAME#v}" >> $GITHUB_OUTPUT
-
-      - name: Inject version into source files
-        run: |
-          VERSION=${{ steps.version.outputs.VERSION }}
-          DATE=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
-          echo "Injecting version $VERSION from tag $GITHUB_REF_NAME..."
-
-          # 1. extension/manifest.base.json
-          jq --arg v "$VERSION" '.version = $v' extension/manifest.base.json > tmp.json && mv tmp.json extension/manifest.base.json
-          echo "  ✓ manifest.base.json -> $VERSION"
-
-          # 2. shared/constants.js — APP_VERSION
-          sed -i "s/export const APP_VERSION = [\"'].*[\"']/export const APP_VERSION = \"$VERSION\"/" shared/constants.js
-          echo "  ✓ shared/constants.js -> $VERSION"
-
-          # 3. package.json
-          jq --arg v "$VERSION" '.version = $v' package.json > tmp.json && mv tmp.json package.json
-          echo "  ✓ package.json -> $VERSION"
-
-          # 4. package-lock.json root package metadata
-          jq --arg v "$VERSION" '.version = $v | .packages[""].version = $v' package-lock.json > tmp.json && mv tmp.json package-lock.json
-          echo "  ✓ package-lock.json -> $VERSION"
-
-          # 5. website/version.json
-          jq -n --arg v "$VERSION" --arg d "$DATE" '{version: $v, date: $d}' > website/version.json
-          echo "  ✓ website/version.json -> version $VERSION, date $DATE"
-
-          # 6. website/template.html — SoftwareApplication schema
-          sed -i "s/\"softwareVersion\": \".*\"/\"softwareVersion\": \"$VERSION\"/" website/template.html
-          echo "  ✓ website/template.html -> softwareVersion $VERSION"
-
-          # 7. website/llms.txt — machine-readable release metadata
-          sed -i "s/Current website release: .*/Current website release: $VERSION/" website/llms.txt
-          echo "  ✓ website/llms.txt -> $VERSION"
-
-          # 8. README.md — version badge & banner
-          sed -i "s|Release-v[0-9]\+\.[0-9]\+\.[0-9]\+-blue|Release-v$VERSION-blue|g" README.md
-          sed -i "s/New v[0-9]\+\.[0-9]\+\.[0-9]\+ Release/New v$VERSION Release/g" README.md
-          echo "  ✓ README.md -> v$VERSION"
-
-          echo "Version injection complete."
-
-      - name: Commit and push version updates back to main
-        run: |
-          git config --local user.email "action@github.com"
-          git config --local user.name "GitHub Action"
-          git add extension/manifest.base.json shared/constants.js package.json package-lock.json website/version.json website/template.html website/llms.txt README.md
-          git commit -m "chore(release): update versions to $GITHUB_REF_NAME [skip ci]" || echo "No changes to commit"
-          git push origin HEAD:main
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: Build Extensions
-        run: |
-          npm ci
-          npm run build:extension
-
-      - name: Generate extension checksums
-        run: |
-          cd dist
-          sha256sum koalasync-chrome.zip koalasync-firefox.zip > SHA256SUMS
-          cat SHA256SUMS
-
-      - name: Generate artifact attestation for extensions
-        uses: actions/attest@v4
-        with:
-          subject-path: dist/koalasync-*.zip
-
-      - name: Build Website
-        run: node website/build.cjs
-
-      - name: Upload Website Artifacts
-        uses: actions/upload-artifact@v7
-        with:
-          name: website-www
-          path: website/www/
-          if-no-files-found: error
-
-      - name: Create GitHub Release
-        uses: softprops/action-gh-release@v3
-        with:
-          files: |
-            dist/koalasync-chrome.zip
-            dist/koalasync-firefox.zip
-            dist/SHA256SUMS
-          name: Release ${{ github.ref_name }}
-          generate_release_notes: true
-          draft: false
-          prerelease: false
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-      - name: Verify published extension release
-        run: node scripts/verify-published-release.mjs "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY"
+      - name: Publish verified GitHub release
+        run: gh release edit "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY" --draft=false --verify-tag
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index abba016..4fce658 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -96,7 +96,9 @@ KoalaSync uses a **single source of truth** for all protocol constants in `share
 ## Version Numbers
 
 > [!CAUTION]
-> **Never manually bump version numbers.** The CI pipeline injects the version from the git tag into `manifest.base.json`, `shared/constants.js`, and `package.json` during release builds. Manual bumps cause conflicts.
+> **Never edit release versions independently.** Release maintainers run
+> `npm run prepare:release -- MAJOR.MINOR.PATCH` on a branch and merge the
+> resulting version changes through a CI-green pull request before tagging.
 
 ---
 
diff --git a/docs/AI_INIT.md b/docs/AI_INIT.md
index 7fddb36..b1a0ae2 100644
--- a/docs/AI_INIT.md
+++ b/docs/AI_INIT.md
@@ -118,17 +118,23 @@ Before starting any task, committing, or pushing, you **MUST** run `git pull --r
 > [!CAUTION]
 > **AI AGENTS MUST FOLLOW THIS EXACT SEQUENCE WHEN RELEASING A NEW VERSION OR TAGGING.**
 > 
-> **🚫 NO MANUAL VERSION BUMPING**: You MUST **NEVER** manually modify the version strings in `package.json`, `extension/manifest.base.json`, or `website/version.json`. The GitHub Actions CI pipeline automatically extracts the version from the git tag (e.g. `v2.0.5` -> `2.0.5`), injects it into all target files, and commits the updates back to `main` with `[skip ci]`. Manual bumps will cause merge conflicts and build failures.
+> **🚫 NO INDEPENDENT VERSION EDITS**: Run `npm run prepare:release -- MAJOR.MINOR.PATCH` on a release-preparation branch. Never edit only one version source, and never expect the tag workflow to modify `main`.
 > - **Website Versioning**: **NEVER** manually modify generated version strings in `website/www/`. The website build injects version data from `website/version.json` into generated output.
 1. **MANDATORY SYNTAX & LINT CHECKS**: Before staging, committing, or pushing any changes, you **MUST** run both checks on every modified JavaScript file:
    - **Syntax Validation**: Run `node -c` on every single modified JavaScript file (e.g., `node -c extension/background.js` and `node -c extension/content.js`). **NEVER** commit or push code that fails this check.
    - **ESLint Validation**: Run `npm run lint` (or `npx eslint .`). The output must show **zero errors and zero warnings**. ESLint is configured to catch undefined variables, unused vars, unreachable code, and other semantic issues. **NEVER** commit or push code that fails this check.
-2. Commit all verified code changes and push to `main`.
-3. Create and push a new tag. **MANDATORY**: Tags MUST start with a `v` (e.g., `v1.4.0`). The GitHub Actions release workflow is strictly configured to ignore any tags without the `v` prefix.
+2. Commit the prepared version and release-note changes on a branch, push it,
+   open a pull request, and wait for required `verify`, `node20`, and `e2e`
+   checks. Direct pushes to `main` are not part of the release process.
+3. After the PR is merged, update local `main` and create an annotated exact
+   SemVer tag (`git tag -a v1.4.0 -m "Release v1.4.0"`) on the same commit as
+   `origin/main`.
    - **🚫 TAG IMMUTABILITY**: Once a tag is pushed to `origin`, it is **PERMANENT**. You MUST **NEVER** reuse, move, or force-push an existing tag — not even to "fix" a mistake. If a release is missing a fix, increment the version and create a **new** tag (e.g., `v1.7.0` → `v1.7.1`). Tags are immutable identifiers; moving them breaks CI pipelines, corrupts the release history, and causes unreproducible builds.
    - **🚫 WHEN NOT TO TAG**: Do NOT create a release tag for changes that do NOT affect the shipped extension or server artifacts. Website text changes, documentation updates (`.md` files), and landing page content do NOT require a version tag. Tags trigger the full CI pipeline (Docker build, extension packaging, GitHub Release) — running this for a typo fix wastes CI resources and creates meaningless releases. Only tag when extension code (`extension/`), server code (`server/`), or shared protocol constants (`shared/`) have changed.
-4. The CI will extract the version from the tag (e.g., `v1.4.0` → `1.4.0`), inject it into all source files, build the extension artifacts, publish the Docker image, and create a GitHub Release.
-5. Verify the release builds on GitHub Actions.
+4. The release workflow validates the unchanged tagged source, creates a draft
+   release, publishes and verifies the relay image, and makes the release public
+   only after every gate succeeds.
+5. Verify GitHub assets, attestations, GHCR platforms/digest, and health smoke.
 
 ### 🚫 Force Push Policy
 > [!CAUTION]
diff --git a/docs/SYNC_GUIDE.md b/docs/SYNC_GUIDE.md
index df0f69b..6fec6ac 100644
--- a/docs/SYNC_GUIDE.md
+++ b/docs/SYNC_GUIDE.md
@@ -35,7 +35,10 @@ The build script performs the following actions:
 The system enforces a strict `protocolVersion` check during the `JOIN_ROOM` handshake. 
 - The version is defined in `shared/constants.js`.
 - If the extension and server versions mismatch, the server will reject the connection with an `Incompatible protocol version` error.
-- **Never manually bump version numbers**. The CI pipeline automatically injects the version from the git tag into `manifest.base.json`, `shared/constants.js`, and `package.json` during release builds. Run the build script to synchronize other constant updates.
+- Never edit release versions independently. Run
+  `npm run prepare:release -- MAJOR.MINOR.PATCH` on a release-preparation branch;
+  the release tag is accepted only after that change reaches `main` with all CI
+  checks passing.
 
 > [!CAUTION]
 > **NEVER** edit the files inside `extension/shared/` directly. They will be overwritten the next time the build script is run. Always edit the files in the root `shared/` directory and then run the build script.
diff --git a/docs/devops.md b/docs/devops.md
index a9d08e0..6cf702b 100644
--- a/docs/devops.md
+++ b/docs/devops.md
@@ -4,30 +4,32 @@ This document describes the deployment and release process for KoalaSync.
 
 ## Tag-Based Releases
 
-KoalaSync uses a fully automated release pipeline triggered by Git tags. 
+KoalaSync uses a gated release pipeline triggered by immutable Git tags.
 
 > [!IMPORTANT]
-> **DO NOT** manually bump the version numbers in any files (such as `package.json`, `manifest.base.json`, `shared/constants.js`, etc.) before creating a release. 
-> Bumping versions manually is redundant, leads to conflicts, and is completely handled by the CI/CD pipeline.
+> **DO NOT** edit individual version files or tag an unmerged branch. Run
+> `npm run prepare:release -- MAJOR.MINOR.PATCH` on a branch, review all generated
+> source changes, and merge them through a pull request with successful CI.
 
 ### How it Works
 
-When you push a Git tag matching `v*` (e.g., `v2.5.1`), the GitHub Actions release workflow (`.github/workflows/release.yml`) is triggered. The workflow performs the following actions:
+When an annotated tag matching exact `vMAJOR.MINOR.PATCH` is pushed, the GitHub
+Actions workflow performs these ordered gates:
 
-1. **Extracts the version** from the tag (e.g., `2.5.1` from `v2.5.1`).
-2. **Injects the version** automatically into the following files:
-   - `extension/manifest.base.json`
-   - `shared/constants.js` (updates `APP_VERSION`)
-   - `package.json`
-   - `package-lock.json` (root package metadata)
-   - `website/version.json`
-   - `website/template.html` (updates `softwareVersion` schema)
-   - `README.md` (updates badge and announcement banner)
-   - `website/sitemap.xml` (updates `lastmod` dates)
-3. **Commits and pushes** these version updates back to the `main` branch automatically with the commit message `chore(release): update versions to vX.X.X [skip ci]`.
-4. **Builds the extension** for both Chrome and Firefox and publishes the zipped archives with a `SHA256SUMS` checksum file and signed provenance attestations.
-5. **Builds the website** and uploads website artifacts.
-6. **Builds and publishes** the Docker image for the relay server to the GitHub Container Registry (`ghcr.io`).
+1. Confirms that the tag is annotated, points exactly at current `origin/main`,
+   and matches every committed version source.
+2. Requires successful `verify`, `node20`, and `e2e` checks for that commit.
+3. Re-runs release verification, cross-browser E2E, and an unpublished relay
+   container smoke test.
+4. Builds and locally validates Chrome/Firefox archives, checksums, AMO output,
+   website output, archive parity, and manifests.
+5. Creates an attested **draft** GitHub Release.
+6. Publishes the multi-architecture relay image, verifies both platforms,
+   attestation identity, digest, tag source, and a running health check.
+7. Makes the GitHub Release public only after every preceding gate succeeds.
+
+The release workflow never writes to `main` and never derives shell code from a
+tag. Version changes must pass normal branch protection first.
 
 ---
 
@@ -35,18 +37,29 @@ When you push a Git tag matching `v*` (e.g., `v2.5.1`), the GitHub Actions relea
 
 To release a new version (e.g., `v2.5.1`), follow these steps:
 
-1. Make sure your local repository is synced on `main`:
+1. Create a release-preparation branch from current `main` and update every
+   version source atomically:
    ```bash
    git checkout main
    git pull origin main
+   git checkout -b release/v2.5.1
+   npm run prepare:release -- 2.5.1
+   npm run verify
    ```
-2. Create a local Git tag:
+2. Commit the release notes and prepared version changes, open a pull request,
+   and wait for required `verify`, `node20`, and `e2e` checks.
+3. After the PR is merged, fast-forward local `main` and create an **annotated**
+   tag on that exact commit:
    ```bash
-   git tag v2.5.1
+   git checkout main
+   git pull --ff-only origin main
+   git tag -a v2.5.1 -m "Release v2.5.1"
    ```
-3. Push the tag to GitHub:
+4. Verify the tag target, then push it once:
    ```bash
+   test "$(git rev-parse v2.5.1^{commit})" = "$(git rev-parse origin/main)"
    git push origin v2.5.1
    ```
 
-The release pipeline will take care of the rest! You can monitor the progress under the **Actions** tab of the GitHub repository.
+Never reuse or move a published tag. Monitor every release job and verify both
+the public GitHub assets and GHCR digest before calling the release complete.
diff --git a/extension/host-access.test.mjs b/extension/host-access.test.mjs
index 82d5e2c..f3767b0 100644
--- a/extension/host-access.test.mjs
+++ b/extension/host-access.test.mjs
@@ -1,7 +1,7 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { describe, expect, it } from 'vitest';
+import { afterEach, describe, expect, it, vi } from 'vitest';
 import {
     HOST_ACCESS_REQUIRED_STATUS,
     addTabHostAccessRequest,
@@ -16,6 +16,8 @@ import {
 const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
 
 describe('host access helpers', () => {
+    afterEach(() => vi.useRealTimers());
+
     it('normalizes only positive safe tab IDs', () => {
         expect(HOST_ACCESS_REQUIRED_STATUS).toBe('host_permission_required');
         for (const invalid of [null, undefined, '', 0, true, [42], '42.5', Number.MAX_SAFE_INTEGER + 1]) {
@@ -38,6 +40,11 @@ describe('host access helpers', () => {
         });
         expect(describeTabUrl('chrome://extensions/')).toBeNull();
         expect(describeTabUrl('not a url')).toBeNull();
+        expect(describeTabUrl('file:///Users/koala/movie.mp4')).toEqual({
+            url: 'file:///Users/koala/movie.mp4',
+            host: 'local file',
+            originPattern: 'file:///*'
+        });
     });
 
     it('checks the selected tab origin and preserves an unknown callback result', async () => {
@@ -112,9 +119,43 @@ describe('host access helpers', () => {
         };
         await expect(requestOriginPermission(callbackChrome, 'https://video.example/*')).resolves.toBe(true);
         await expect(requestOriginPermission({ permissions: {} }, 'https://video.example/*')).resolves.toBeNull();
+        await expect(requestOriginPermission(callbackChrome, '')).resolves.toBeNull();
+        await expect(requestOriginPermission({
+            permissions: { request: async () => { throw new Error('denied'); } }
+        }, 'https://video.example/*')).resolves.toBe(false);
+        await expect(addTabHostAccessRequest({
+            permissions: { addHostAccessRequest: async () => { throw new Error('denied'); } }
+        }, 42)).resolves.toBe(false);
+        await expect(removeTabHostAccessRequest({
+            permissions: { removeHostAccessRequest: async () => { throw new Error('denied'); } }
+        }, 42)).resolves.toBe(false);
         expect(isHostAccessError(new Error('Missing host permission for the tab'))).toBe(true);
         expect(isHostAccessError(new Error('No tab with id: 42'))).toBe(false);
     });
+
+    it('treats permission inspection errors and timeouts as advisory unknowns', async () => {
+        const base = {
+            tabs: { get: async () => ({ url: 'https://video.example/watch' }) }
+        };
+        await expect(inspectTabHostAccess({
+            ...base,
+            permissions: { contains: async () => { throw new Error('permission API failed'); } }
+        }, 42)).resolves.toMatchObject({ granted: null });
+
+        await expect(inspectTabHostAccess({
+            ...base,
+            runtime: { lastError: { message: 'permission callback failed' } },
+            permissions: { contains: (_request, callback) => callback(false) }
+        }, 42)).resolves.toMatchObject({ granted: null });
+
+        vi.useFakeTimers();
+        const pending = inspectTabHostAccess({
+            ...base,
+            permissions: { contains: () => undefined }
+        }, 42);
+        await vi.advanceTimersByTimeAsync(1000);
+        await expect(pending).resolves.toMatchObject({ granted: null });
+    });
 });
 
 describe('host access recovery contracts', () => {
diff --git a/extension/popup.html b/extension/popup.html
index 8a8035e..05af8db 100644
--- a/extension/popup.html
+++ b/extension/popup.html
@@ -1413,16 +1413,16 @@
                     </a>
                 </div>
 
-    <div class="tabs">
-        <button class="tab-btn active" data-tab="tab-room" data-i18n="TAB_ROOM" data-i18n-title="TAB_ROOM_TOOLTIP" title="Room settings and connection">Room</button>
-        <button class="tab-btn" data-tab="tab-sync" data-i18n="TAB_SYNC" data-i18n-title="TAB_SYNC_TOOLTIP" title="Video sync controls and remote actions">Sync</button>
-        <button class="tab-btn" data-tab="tab-settings" data-i18n="TAB_SETTINGS" data-i18n-title="TAB_SETTINGS_TOOLTIP" title="Extension preferences">Settings</button>
-        <button class="tab-btn" data-tab="tab-dev" data-i18n="TAB_STATUS" data-i18n-title="TAB_STATUS_TOOLTIP" title="Advanced Diagnostics & Logs">Status</button>
-        <button id="devToolsTabBtn" class="tab-btn" data-tab="tab-devtools" style="display:none;">Dev</button>
+    <div class="tabs" role="tablist" aria-label="KoalaSync sections">
+        <button id="tab-room-button" class="tab-btn active" role="tab" aria-selected="true" aria-controls="tab-room" data-tab="tab-room" data-i18n="TAB_ROOM" data-i18n-title="TAB_ROOM_TOOLTIP" title="Room settings and connection">Room</button>
+        <button id="tab-sync-button" class="tab-btn" role="tab" aria-selected="false" aria-controls="tab-sync" tabindex="-1" data-tab="tab-sync" data-i18n="TAB_SYNC" data-i18n-title="TAB_SYNC_TOOLTIP" title="Video sync controls and remote actions">Sync</button>
+        <button id="tab-settings-button" class="tab-btn" role="tab" aria-selected="false" aria-controls="tab-settings" tabindex="-1" data-tab="tab-settings" data-i18n="TAB_SETTINGS" data-i18n-title="TAB_SETTINGS_TOOLTIP" title="Extension preferences">Settings</button>
+        <button id="tab-dev-button" class="tab-btn" role="tab" aria-selected="false" aria-controls="tab-dev" tabindex="-1" data-tab="tab-dev" data-i18n="TAB_STATUS" data-i18n-title="TAB_STATUS_TOOLTIP" title="Advanced Diagnostics & Logs">Status</button>
+        <button id="devToolsTabBtn" class="tab-btn" role="tab" aria-selected="false" aria-controls="tab-devtools" tabindex="-1" data-tab="tab-devtools" style="display:none;">Dev</button>
     </div>
 
     <!-- Room Tab -->
-    <div id="tab-room" class="tab-content active">
+    <div id="tab-room" class="tab-content active" role="tabpanel" aria-labelledby="tab-room-button">
 
         <!-- JOIN SECTION: Visible when not in a room -->
         <div id="section-join">
@@ -1510,7 +1510,7 @@
     </div>
 
     <!-- Sync Tab -->
-    <div id="tab-sync" class="tab-content">
+    <div id="tab-sync" class="tab-content" role="tabpanel" aria-labelledby="tab-sync-button" aria-hidden="true">
         <!-- SYNC ACTIVE: Visible when in a room -->
         <div id="sync-active">
         <div class="form-group" style="position: relative;">
@@ -1576,7 +1576,7 @@
     </div>
     
     <!-- Settings Tab -->
-    <div id="tab-settings" class="tab-content">
+    <div id="tab-settings" class="tab-content" role="tabpanel" aria-labelledby="tab-settings-button" aria-hidden="true">
         <details class="form-group" name="settings-accordion" open>
             <summary title="Change your username, theme, and language." data-i18n="LABEL_SETTINGS_GROUP_PROFILE" data-i18n-title="LABEL_SETTINGS_GROUP_PROFILE_TOOLTIP">Profile &amp; Appearance</summary>
             <div class="details-content">
@@ -1813,7 +1813,7 @@
     </div>
 
     <!-- Dev Tab -->
-    <div id="tab-dev" class="tab-content">
+    <div id="tab-dev" class="tab-content" role="tabpanel" aria-labelledby="tab-dev-button" aria-hidden="true">
         <label title="Current WebSocket connection state" data-i18n="LABEL_CONN_STATUS" data-i18n-title="LABEL_CONN_STATUS_TOOLTIP">Connection Status</label>
         <div id="connStatus" class="info-card" style="display:flex; align-items:center; gap: 10px;">
             <span id="connDot" class="status-dot status-offline"></span>
@@ -1845,7 +1845,7 @@
         <div id="logList"></div>
     </div>
 
-    <div id="tab-devtools" class="tab-content">
+    <div id="tab-devtools" class="tab-content" role="tabpanel" aria-labelledby="devToolsTabBtn" aria-hidden="true">
         <label>Remote Seek</label>
         <div class="info-card" style="display:flex; gap:8px; margin-bottom:15px;">
             <button id="remoteSeekBack" class="secondary" style="flex:1; font-size:12px;">-30s</button>
diff --git a/extension/popup.js b/extension/popup.js
index 5d81aa0..59fbad9 100644
--- a/extension/popup.js
+++ b/extension/popup.js
@@ -1791,12 +1791,22 @@ elements.serverUrl.addEventListener('change', () => {
 
 elements.tabs.forEach(btn => {
     btn.addEventListener('click', () => {
-        elements.tabs.forEach(b => b.classList.remove('active'));
-        elements.contents.forEach(c => c.classList.remove('active'));
+        elements.tabs.forEach(b => {
+            b.classList.remove('active');
+            b.setAttribute('aria-selected', 'false');
+            b.tabIndex = -1;
+        });
+        elements.contents.forEach(c => {
+            c.classList.remove('active');
+            c.setAttribute('aria-hidden', 'true');
+        });
         btn.classList.add('active');
+        btn.setAttribute('aria-selected', 'true');
+        btn.tabIndex = 0;
         
         const targetContent = document.getElementById(btn.dataset.tab);
         targetContent.classList.add('active');
+        targetContent.removeAttribute('aria-hidden');
         
         targetContent.classList.remove('tab-active-animate');
         void targetContent.offsetWidth; // Force reflow to restart animation
@@ -1808,6 +1818,20 @@ elements.tabs.forEach(btn => {
         
         chrome.storage.local.set({ activeTab: btn.dataset.tab });
     });
+
+    btn.addEventListener('keydown', event => {
+        if (!['ArrowLeft', 'ArrowRight', 'Home', 'End'].includes(event.key)) return;
+        const visibleTabs = [...elements.tabs].filter(tab => window.getComputedStyle(tab).display !== 'none');
+        const currentIndex = visibleTabs.indexOf(btn);
+        const nextIndex = event.key === 'Home'
+            ? 0
+            : event.key === 'End'
+                ? visibleTabs.length - 1
+                : (currentIndex + (event.key === 'ArrowRight' ? 1 : -1) + visibleTabs.length) % visibleTabs.length;
+        event.preventDefault();
+        visibleTabs[nextIndex].focus();
+        visibleTabs[nextIndex].click();
+    });
 });
 
 function showToast(message, type = 'info', duration = 3000) {
diff --git a/extension/title-privacy.test.mjs b/extension/title-privacy.test.mjs
index d020e23..846434b 100644
--- a/extension/title-privacy.test.mjs
+++ b/extension/title-privacy.test.mjs
@@ -21,13 +21,20 @@ describe('title privacy', () => {
         expect(normalizeTabTitle('(12) Testvideo - YouTube')).toBe('Testvideo - YouTube');
         expect(normalizeTabTitle('[999+] Testvideo - YouTube')).toBe('Testvideo - YouTube');
         expect(normalizeTabTitle('(500) Days of Summer')).toBe('Days of Summer');
+        for (const title of ['[7] Testvideo', '(99+) Testvideo', '(999+) Testvideo', '(101) Testvideo', '[101] Testvideo']) {
+            expect(normalizeTabTitle(title)).toBe('Testvideo');
+        }
+        expect(normalizeTabTitle(null)).toBeNull();
         expect(normalizeTabTitle('   ')).toBeNull();
+        expect(sanitizeTabTitle('', true)).toBeNull();
     });
 
     it('keeps tab-title and media-title privacy independent', () => {
         expect(sanitizeTabTitle('(12) Private Tab', true)).toBe('Private Tab');
         expect(sanitizeTabTitle('Private Tab', false)).toBeNull();
         expect(sanitizeSharedTitle('Example Movie', 'full')).toBe('Example Movie');
+        expect(sanitizeSharedTitle('', 'full')).toBeNull();
+        expect(sanitizeSharedTitle(null, 'full')).toBeNull();
         expect(sanitizeSharedTitle('Show Name - S01/E04 - Title', 'episode')).toBe('S01E04');
         expect(sanitizeSharedTitle('Folge 7 - Private Server', 'episode')).toBe('EP007');
         expect(sanitizeSharedTitle('Example Movie', 'episode')).toBeNull();
diff --git a/package-lock.json b/package-lock.json
index 3c68566..63b6f7a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -23,7 +23,7 @@
         "vitest": "^4.1.10"
       },
       "engines": {
-        "node": ">=20.9.0"
+        "node": ">=20.19.0"
       }
     },
     "node_modules/@babel/code-frame": {
diff --git a/package.json b/package.json
index 0b737e4..1f2a46e 100644
--- a/package.json
+++ b/package.json
@@ -5,13 +5,14 @@
   "private": true,
   "type": "module",
   "engines": {
-    "node": ">=20.9.0"
+    "node": ">=20.19.0"
   },
   "scripts": {
     "build:extension": "node scripts/build-extension.cjs",
     "indexnow": "node website/submit-indexnow.cjs",
     "lint": "eslint .",
     "lint:fix": "eslint . --fix",
+    "prepare:release": "node scripts/prepare-release.mjs",
     "subset-flags": "node website/tools/subset-flag-font.mjs",
     "test": "npm run verify",
     "test:e2e": "playwright test --config tests/e2e/playwright.config.mjs",
diff --git a/scripts/README.md b/scripts/README.md
index 09c9062..4b6a70b 100644
--- a/scripts/README.md
+++ b/scripts/README.md
@@ -10,6 +10,7 @@ npm run verify
 npm run lint
 npm run test:unit
 npm run test:coverage
+npm run prepare:release -- 3.1.5
 ```
 
 - `npm run build:extension` runs `scripts/build-extension.cjs`.
@@ -17,6 +18,7 @@ npm run test:coverage
 - `npm run lint` runs ESLint across the repository.
 - `npm run test:unit` runs Vitest tests.
 - `npm run test:coverage` runs the same tests with the enforced coverage floor.
+- `npm run prepare:release -- MAJOR.MINOR.PATCH` updates every release-version source consistently before the release PR.
 
 ## build-extension.cjs
 
@@ -89,10 +91,17 @@ both global and risk-specific per-module floors. Browser entry points
 (`background.js`, `content.js`, and `popup.js`) and server process startup are
 deliberately measured by extension E2E and integration tests instead of being
 reported as zero-coverage unit code.
+`scripts/check-coverage-inventory.mjs` additionally requires every JavaScript
+source file to be classified as V8-covered or assigned to a named external
+integration gate. New unclassified files fail `npm run verify`.
 
 ## Published Release Verification
 
-After a GitHub Release is created, the release workflow runs:
+Before publication, the release workflow validates the exact annotated SemVer
+tag, requires it to point at current `origin/main`, requires successful
+`verify`, `node20`, and `e2e` checks, and runs the complete gates again. It then
+creates a draft release, publishes and smoke-tests the relay image, and only
+afterwards makes the GitHub Release public. The published-asset gate runs:
 
 ```bash
 node scripts/verify-published-release.mjs v3.1.4 --repo Shik3i/KoalaSync
diff --git a/scripts/check-coverage-inventory.mjs b/scripts/check-coverage-inventory.mjs
new file mode 100644
index 0000000..a5b463d
--- /dev/null
+++ b/scripts/check-coverage-inventory.mjs
@@ -0,0 +1,62 @@
+#!/usr/bin/env node
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { EXTERNALLY_GATED_SOURCES, VITEST_COVERAGE_INCLUDE } from './coverage-plan.mjs';
+
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+const SOURCE_ROOTS = Object.freeze(['extension', 'scripts', 'server', 'shared', 'website']);
+const SOURCE_EXTENSION = /\.(?:cjs|js|mjs)$/u;
+const TEST_FILE = /\.test\.(?:cjs|js|mjs)$/u;
+const GENERATED_OR_DEPENDENCY_DIRECTORIES = new Set(['extension/shared', 'server/node_modules', 'website/www']);
+
+export function validateCoverageInventory(discoveredSources, coveredSources, externallyGatedSources) {
+    const discovered = new Set(discoveredSources);
+    const assignments = [...coveredSources, ...externallyGatedSources];
+    const assigned = new Set();
+    const duplicates = new Set();
+    for (const source of assignments) {
+        if (assigned.has(source)) duplicates.add(source);
+        assigned.add(source);
+    }
+    const unclassified = [...discovered].filter(source => !assigned.has(source)).sort();
+    const stale = [...assigned].filter(source => !discovered.has(source)).sort();
+    if (duplicates.size || unclassified.length || stale.length) {
+        const details = [];
+        if (duplicates.size) details.push(`assigned more than once: ${[...duplicates].sort().join(', ')}`);
+        if (unclassified.length) details.push(`unclassified sources: ${unclassified.join(', ')}`);
+        if (stale.length) details.push(`stale assignments: ${stale.join(', ')}`);
+        throw new Error(details.join('; '));
+    }
+}
+
+function collectSources(directory, output = []) {
+    for (const entry of fs.readdirSync(directory, { withFileTypes: true })) {
+        const absolutePath = path.join(directory, entry.name);
+        if (entry.isDirectory()) {
+            const relativeDirectory = path.relative(repoRoot, absolutePath).split(path.sep).join('/');
+            if (!GENERATED_OR_DEPENDENCY_DIRECTORIES.has(relativeDirectory)) collectSources(absolutePath, output);
+        } else if (SOURCE_EXTENSION.test(entry.name) && !TEST_FILE.test(entry.name)) {
+            output.push(path.relative(repoRoot, absolutePath).split(path.sep).join('/'));
+        }
+    }
+    return output;
+}
+
+function main() {
+    const discoveredSources = SOURCE_ROOTS.flatMap(root => collectSources(path.join(repoRoot, root))).sort();
+    const externallyGatedSources = Object.values(EXTERNALLY_GATED_SOURCES).flat();
+    validateCoverageInventory(discoveredSources, VITEST_COVERAGE_INCLUDE, externallyGatedSources);
+    console.log(`Coverage inventory passed: ${VITEST_COVERAGE_INCLUDE.length} V8-covered, ${externallyGatedSources.length} externally gated`);
+}
+
+const isMainModule = process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1];
+if (isMainModule) {
+    try {
+        main();
+    } catch (error) {
+        console.error(`Coverage inventory failed: ${error.message}`);
+        process.exitCode = 1;
+    }
+}
diff --git a/scripts/coverage-plan.mjs b/scripts/coverage-plan.mjs
new file mode 100644
index 0000000..601dabd
--- /dev/null
+++ b/scripts/coverage-plan.mjs
@@ -0,0 +1,68 @@
+export const VITEST_COVERAGE_INCLUDE = Object.freeze([
+    'server/chat.js',
+    'server/ops.js',
+    'server/rate-limiter.js',
+    'shared/blacklist.js',
+    'shared/invite-links.js',
+    'shared/names.js',
+    'extension/chat-activity.js',
+    'extension/chat-crypto.js',
+    'extension/chat-format.js',
+    'extension/chat-session.js',
+    'extension/chat-wire.js',
+    'extension/episode-utils.js',
+    'extension/host-access.js',
+    'extension/media-frame-target.js',
+    'extension/title-privacy.js',
+    'scripts/release-artifact-checks.mjs'
+]);
+
+// Exact list by design: adding a runtime/tooling module requires choosing its
+// automated gate instead of silently leaving it unmeasured.
+export const EXTERNALLY_GATED_SOURCES = Object.freeze({
+    'packed extension E2E': Object.freeze([
+        'extension/audio-options.js',
+        'extension/background.js',
+        'extension/bridge.js',
+        'extension/chat-overlay.js',
+        'extension/content.js',
+        'extension/i18n.js',
+        'extension/media-frame-monitor.js',
+        'extension/modules/tab-manager.js',
+        'extension/page-api-seek-overrides.js',
+        'extension/popup.js',
+        'extension/theme-init.js',
+        'shared/constants.js'
+    ]),
+    'relay integration': Object.freeze([
+        'server/index.js'
+    ]),
+    'release and repository integration': Object.freeze([
+        'scripts/build-extension.cjs',
+        'scripts/check-coverage-inventory.mjs',
+        'scripts/coverage-plan.mjs',
+        'scripts/prepare-release.mjs',
+        'scripts/release-preflight.mjs',
+        'scripts/test-audio-settings.mjs',
+        'scripts/test-chat-settings.mjs',
+        'scripts/test-content-video-finder.cjs',
+        'scripts/test-locales.cjs',
+        'scripts/test-popup-refresh-cooldown.mjs',
+        'scripts/test-server-routes.mjs',
+        'scripts/test-server-ws.mjs',
+        'scripts/test-website-locales.mjs',
+        'scripts/test-website-theme.mjs',
+        'scripts/translate-locales-tool.cjs',
+        'scripts/validate-brand-names.cjs',
+        'scripts/verify-published-release.mjs',
+        'scripts/verify-release.mjs'
+    ]),
+    'website build and contract checks': Object.freeze([
+        'website/app.js',
+        'website/build.cjs',
+        'website/flag-font-utils.cjs',
+        'website/lang-init.js',
+        'website/submit-indexnow.cjs',
+        'website/tools/subset-flag-font.mjs'
+    ])
+});
diff --git a/scripts/coverage-plan.test.mjs b/scripts/coverage-plan.test.mjs
new file mode 100644
index 0000000..06a3f6f
--- /dev/null
+++ b/scripts/coverage-plan.test.mjs
@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest';
+import { validateCoverageInventory } from './check-coverage-inventory.mjs';
+
+describe('coverage inventory', () => {
+    it('accepts an exact, unique classification', () => {
+        expect(() => validateCoverageInventory(
+            ['covered.js', 'browser.js'],
+            ['covered.js'],
+            ['browser.js']
+        )).not.toThrow();
+    });
+
+    it('rejects unclassified, stale, and duplicate assignments', () => {
+        expect(() => validateCoverageInventory(['new.js'], [], []))
+            .toThrow('unclassified sources: new.js');
+        expect(() => validateCoverageInventory([], ['deleted.js'], []))
+            .toThrow('stale assignments: deleted.js');
+        expect(() => validateCoverageInventory(['same.js'], ['same.js'], ['same.js']))
+            .toThrow('assigned more than once: same.js');
+    });
+});
diff --git a/scripts/prepare-release.mjs b/scripts/prepare-release.mjs
new file mode 100644
index 0000000..f7c2fc2
--- /dev/null
+++ b/scripts/prepare-release.mjs
@@ -0,0 +1,80 @@
+#!/usr/bin/env node
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { versionFromTag } from './release-artifact-checks.mjs';
+
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+
+export function replaceExactly(text, pattern, replacement, label) {
+    const matches = String(text).match(pattern);
+    if (!matches || matches.length !== 1) {
+        throw new Error(`${label} must contain exactly one release-version marker`);
+    }
+    return text.replace(pattern, replacement);
+}
+
+function writeJson(relativePath, update) {
+    const absolutePath = path.join(repoRoot, relativePath);
+    const value = JSON.parse(fs.readFileSync(absolutePath, 'utf8'));
+    update(value);
+    fs.writeFileSync(absolutePath, `${JSON.stringify(value, null, 2)}\n`, 'utf8');
+}
+
+function updateText(relativePath, pattern, replacement, label) {
+    const absolutePath = path.join(repoRoot, relativePath);
+    const current = fs.readFileSync(absolutePath, 'utf8');
+    fs.writeFileSync(absolutePath, replaceExactly(current, pattern, replacement, label), 'utf8');
+}
+
+export function prepareRelease(version, date = new Date()) {
+    versionFromTag(`v${version}`);
+    const timestamp = date.toISOString().replace(/\.\d{3}Z$/u, 'Z');
+    writeJson('package.json', value => { value.version = version; });
+    writeJson('package-lock.json', value => {
+        value.version = version;
+        value.packages[''].version = version;
+    });
+    writeJson('extension/manifest.base.json', value => { value.version = version; });
+    writeJson('website/version.json', value => {
+        value.version = version;
+        value.date = timestamp;
+    });
+    updateText(
+        'shared/constants.js',
+        /export const APP_VERSION = ["'][^"']+["'];/gu,
+        `export const APP_VERSION = "${version}";`,
+        'shared/constants.js'
+    );
+    updateText(
+        'website/template.html',
+        /"softwareVersion": "[^"]+"/gu,
+        `"softwareVersion": "${version}"`,
+        'website/template.html'
+    );
+    updateText(
+        'website/llms.txt',
+        /Current website release: .+/gu,
+        `Current website release: ${version}`,
+        'website/llms.txt'
+    );
+    updateText(
+        'README.md',
+        /Release-v\d+\.\d+\.\d+-blue/gu,
+        `Release-v${version}-blue`,
+        'README.md release badge'
+    );
+    console.log(`Prepared release v${version} at ${timestamp}`);
+}
+
+const isMainModule = process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1];
+if (isMainModule) {
+    try {
+        if (process.argv.length !== 3) throw new Error('Usage: npm run prepare:release -- MAJOR.MINOR.PATCH');
+        prepareRelease(process.argv[2]);
+    } catch (error) {
+        console.error(`Release preparation failed: ${error.message}`);
+        process.exitCode = 1;
+    }
+}
diff --git a/scripts/prepare-release.test.mjs b/scripts/prepare-release.test.mjs
new file mode 100644
index 0000000..8e1faf1
--- /dev/null
+++ b/scripts/prepare-release.test.mjs
@@ -0,0 +1,13 @@
+import { describe, expect, it } from 'vitest';
+import { replaceExactly } from './prepare-release.mjs';
+
+describe('release preparation helpers', () => {
+    it('replaces one and only one version marker', () => {
+        expect(replaceExactly('version=3.1.4', /version=\d+\.\d+\.\d+/gu, 'version=3.1.5', 'fixture'))
+            .toBe('version=3.1.5');
+        expect(() => replaceExactly('none', /version=\d+/gu, 'version=4', 'fixture'))
+            .toThrow('fixture must contain exactly one release-version marker');
+        expect(() => replaceExactly('version=1 version=2', /version=\d+/gu, 'version=3', 'fixture'))
+            .toThrow('fixture must contain exactly one release-version marker');
+    });
+});
diff --git a/scripts/release-preflight.mjs b/scripts/release-preflight.mjs
new file mode 100644
index 0000000..da6dcaa
--- /dev/null
+++ b/scripts/release-preflight.mjs
@@ -0,0 +1,111 @@
+#!/usr/bin/env node
+
+import { execFileSync } from 'node:child_process';
+import fs from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+import { versionFromTag } from './release-artifact-checks.mjs';
+
+export const REQUIRED_RELEASE_CHECKS = Object.freeze(['verify', 'node20', 'e2e']);
+
+export function parseCheckRuns(text) {
+    return String(text).split(/\r?\n/u).filter(Boolean).map(line => {
+        const [name, conclusion, url = ''] = line.split('\t');
+        if (!name || !conclusion) throw new Error(`Invalid check-run record: ${line}`);
+        return { name, conclusion, url };
+    });
+}
+
+export function validateRequiredChecks(checkRuns, required = REQUIRED_RELEASE_CHECKS) {
+    for (const name of required) {
+        const matches = checkRuns.filter(check => check.name === name);
+        if (matches.length === 0) throw new Error(`Required check is missing for the release commit: ${name}`);
+        if (matches.some(check => check.conclusion !== 'success')) {
+            const conclusions = matches.map(check => check.conclusion).join(', ');
+            throw new Error(`Required check ${name} did not succeed: ${conclusions}`);
+        }
+    }
+}
+
+function run(command, args) {
+    return execFileSync(command, args, {
+        cwd: process.cwd(),
+        encoding: 'utf8',
+        stdio: ['ignore', 'pipe', 'pipe']
+    }).trim();
+}
+
+export function validateRepositoryName(repo) {
+    if (!/^[^/\s]+\/[^/\s]+$/u.test(repo || '')) {
+        throw new Error(`Invalid GitHub repository: ${repo || '<empty>'}`);
+    }
+    return repo;
+}
+
+export function validateVersionSnapshot(expectedVersion, snapshot) {
+    for (const [label, actualVersion] of Object.entries(snapshot)) {
+        if (actualVersion !== expectedVersion) {
+            throw new Error(`${label} version ${actualVersion || '<missing>'} does not match tag version ${expectedVersion}`);
+        }
+    }
+}
+
+export function validateReleaseSourceVersion(expectedVersion, repoRoot = process.cwd()) {
+    const readJson = relativePath => JSON.parse(fs.readFileSync(path.join(repoRoot, relativePath), 'utf8'));
+    const packageJson = readJson('package.json');
+    const packageLock = readJson('package-lock.json');
+    const manifest = readJson('extension/manifest.base.json');
+    const websiteVersion = readJson('website/version.json');
+    const constants = fs.readFileSync(path.join(repoRoot, 'shared/constants.js'), 'utf8');
+    const appVersion = /export const APP_VERSION = ["']([^"']+)["']/u.exec(constants)?.[1] || '';
+    validateVersionSnapshot(expectedVersion, {
+        'package.json': packageJson.version,
+        'package-lock.json': packageLock.version,
+        'package-lock root package': packageLock.packages?.['']?.version,
+        'extension manifest': manifest.version,
+        'shared constants': appVersion,
+        'website/version.json': websiteVersion.version
+    });
+}
+
+export function verifyReleaseRef({ tag, repo }) {
+    const version = versionFromTag(tag);
+    validateRepositoryName(repo);
+    validateReleaseSourceVersion(version);
+    const tagRef = `refs/tags/${tag}`;
+    if (run('git', ['cat-file', '-t', tagRef]) !== 'tag') {
+        throw new Error(`${tag} must be an annotated tag`);
+    }
+    const tagCommit = run('git', ['rev-list', '-n', '1', tagRef]);
+    const mainCommit = run('git', ['rev-parse', 'origin/main']);
+    if (tagCommit !== mainCommit) {
+        throw new Error(`Release tag ${tag} points to ${tagCommit}, but origin/main is ${mainCommit}`);
+    }
+
+    const checks = parseCheckRuns(run('gh', [
+        'api', `repos/${repo}/commits/${tagCommit}/check-runs`,
+        '--jq', '.check_runs[] | [.name, .conclusion, .html_url] | @tsv'
+    ]));
+    validateRequiredChecks(checks);
+    return { version, tagCommit };
+}
+
+function main() {
+    const tag = process.env.GITHUB_REF_NAME || '';
+    const repo = process.env.GITHUB_REPOSITORY || '';
+    const outputPath = process.env.GITHUB_OUTPUT || '';
+    const result = verifyReleaseRef({ tag, repo });
+    if (!outputPath) throw new Error('GITHUB_OUTPUT is required');
+    fs.appendFileSync(outputPath, `version=${result.version}\ntag_commit=${result.tagCommit}\n`, 'utf8');
+    console.log(`Release preflight accepted ${tag} at ${result.tagCommit}`);
+}
+
+const isMainModule = process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1];
+if (isMainModule) {
+    try {
+        main();
+    } catch (error) {
+        console.error(`Release preflight failed: ${error.message}`);
+        process.exitCode = 1;
+    }
+}
diff --git a/scripts/release-preflight.test.mjs b/scripts/release-preflight.test.mjs
new file mode 100644
index 0000000..52390f7
--- /dev/null
+++ b/scripts/release-preflight.test.mjs
@@ -0,0 +1,59 @@
+import { describe, expect, it } from 'vitest';
+import {
+    parseCheckRuns,
+    validateRepositoryName,
+    validateRequiredChecks,
+    validateVersionSnapshot
+} from './release-preflight.mjs';
+
+describe('release preflight helpers', () => {
+    it('parses successful GitHub check runs', () => {
+        const checks = parseCheckRuns('verify\tsuccess\thttps://example.test/1\nnode20\tsuccess\thttps://example.test/2\ne2e\tsuccess\thttps://example.test/3');
+        expect(checks).toEqual([
+            { name: 'verify', conclusion: 'success', url: 'https://example.test/1' },
+            { name: 'node20', conclusion: 'success', url: 'https://example.test/2' },
+            { name: 'e2e', conclusion: 'success', url: 'https://example.test/3' }
+        ]);
+        expect(() => validateRequiredChecks(checks)).not.toThrow();
+    });
+
+    it('rejects missing, pending, and failed release checks', () => {
+        expect(() => validateRequiredChecks([{ name: 'verify', conclusion: 'success' }]))
+            .toThrow('Required check is missing for the release commit: node20');
+        expect(() => validateRequiredChecks([
+            { name: 'verify', conclusion: 'success' },
+            { name: 'node20', conclusion: 'success' },
+            { name: 'e2e', conclusion: 'in_progress' }
+        ])).toThrow('Required check e2e did not succeed: in_progress');
+        expect(() => validateRequiredChecks([
+            { name: 'verify', conclusion: 'failure' },
+            { name: 'node20', conclusion: 'success' },
+            { name: 'e2e', conclusion: 'success' }
+        ])).toThrow('Required check verify did not succeed: failure');
+        expect(() => validateRequiredChecks([
+            { name: 'verify', conclusion: 'success' },
+            { name: 'verify', conclusion: 'failure' },
+            { name: 'node20', conclusion: 'success' },
+            { name: 'e2e', conclusion: 'success' }
+        ])).toThrow('Required check verify did not succeed: success, failure');
+    });
+
+    it('validates repository names and malformed check output', () => {
+        expect(validateRepositoryName('Shik3i/KoalaSync')).toBe('Shik3i/KoalaSync');
+        for (const invalid of ['', 'KoalaSync', 'owner/repo/extra', 'owner /repo']) {
+            expect(() => validateRepositoryName(invalid)).toThrow('Invalid GitHub repository');
+        }
+        expect(() => parseCheckRuns('verify')).toThrow('Invalid check-run record');
+    });
+
+    it('requires every release source to already match the tag version', () => {
+        expect(() => validateVersionSnapshot('3.1.5', {
+            package: '3.1.5',
+            manifest: '3.1.5'
+        })).not.toThrow();
+        expect(() => validateVersionSnapshot('3.1.5', {
+            package: '3.1.5',
+            manifest: '3.1.4'
+        })).toThrow('manifest version 3.1.4 does not match tag version 3.1.5');
+    });
+});
diff --git a/scripts/verify-published-release.mjs b/scripts/verify-published-release.mjs
index 6b69354..1237200 100644
--- a/scripts/verify-published-release.mjs
+++ b/scripts/verify-published-release.mjs
@@ -85,7 +85,8 @@ async function verify() {
     if (run('git', ['cat-file', '-t', tagRef]).trim() !== 'tag') {
         throw new Error(`${options.tag} must be an annotated tag`);
     }
-    run('git', ['merge-base', '--is-ancestor', tagRef, 'HEAD']);
+    run('git', ['merge-base', '--is-ancestor', tagRef, 'origin/main']);
+    const tagCommit = run('git', ['rev-list', '-n', '1', tagRef]).trim();
 
     const temporaryDirectory = options.assetDir
         ? null
@@ -132,7 +133,14 @@ async function verify() {
             validateManifest(browserName, manifest, version);
             assertRuntimeBuild(browserName, archivePath, version);
             if (!options.skipAttestation && !options.assetDir) {
-                run('gh', ['attestation', 'verify', archivePath, '--repo', repo], { capture: false });
+                run('gh', [
+                    'attestation', 'verify', archivePath,
+                    '--repo', repo,
+                    '--signer-workflow', `${repo}/.github/workflows/release.yml`,
+                    '--source-ref', tagRef,
+                    '--source-digest', tagCommit,
+                    '--deny-self-hosted-runners'
+                ], { capture: false });
             }
         }
         validateArchiveParity(archiveEntries.chrome, archiveEntries.firefox);
diff --git a/scripts/verify-release.mjs b/scripts/verify-release.mjs
index 334988a..d0f2f1a 100644
--- a/scripts/verify-release.mjs
+++ b/scripts/verify-release.mjs
@@ -7,6 +7,7 @@ import path from 'node:path';
 const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
 
 const checks = [
+  ['coverage source inventory', 'node', ['scripts/check-coverage-inventory.mjs']],
   ['vitest unit tests and coverage', 'npm', ['run', 'test:coverage']],
   ['server routes', 'node', ['scripts/test-server-routes.mjs'], {
     env: { ADMIN_METRICS_TOKEN: 'verify-admin-token-with-more-than-32-chars' }
diff --git a/server/rate-limiter.test.mjs b/server/rate-limiter.test.mjs
index 49571bc..f06ee54 100644
--- a/server/rate-limiter.test.mjs
+++ b/server/rate-limiter.test.mjs
@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import {
     checkAdminMetricsAuthRate,
     checkAuthRate,
@@ -12,6 +12,11 @@ import {
     CHAT_MESSAGE_RATE_LIMIT,
     CHAT_MESSAGE_RATE_WINDOW_MS,
     chatMessageCounts,
+    connectionCounts,
+    eventCounts,
+    healthCounts,
+    adminMetricsAuthCounts,
+    roomListCooldowns,
     failedAuthAttempts,
     LEAVE_ROOM_RATE_LIMIT,
     LEAVE_ROOM_RATE_WINDOW_MS,
@@ -180,6 +185,56 @@ describe('remaining relay rate limits', () => {
             stopRateLimitCleanup();
         }).not.toThrow();
     });
+
+    it('clears every rate-limit map', () => {
+        const maps = [
+            connectionCounts,
+            failedAuthAttempts,
+            eventCounts,
+            chatMessageCounts,
+            healthCounts,
+            adminMetricsAuthCounts,
+            roomListCooldowns,
+            leaveRoomCounts
+        ];
+        maps.forEach((map, index) => map.set(`key-${index}`, { count: 1 }));
+        clearRateLimitMaps();
+        maps.forEach(map => expect(map.size).toBe(0));
+    });
+
+    it('removes expired and disconnected entries in both cleanup intervals', async () => {
+        vi.useFakeTimers();
+        vi.setSystemTime(new Date('2026-08-21T10:00:00Z'));
+        const now = Date.now();
+        const sockets = new Map([['connected', {}]]);
+        connectionCounts.set('expired-ip', { count: 1, resetTime: now - 1 });
+        connectionCounts.set('live-ip', { count: 1, resetTime: now + 120000 });
+        eventCounts.set('disconnected', { count: 1, resetTime: now + 120000 });
+        eventCounts.set('connected', { count: 1, resetTime: now + 120000 });
+        chatMessageCounts.set('disconnected', { count: 1, resetTime: now + 120000 });
+        leaveRoomCounts.set('disconnected', { count: 1, resetTime: now + 120000 });
+        healthCounts.set('expired-health', { count: 1, resetTime: now - 1 });
+        adminMetricsAuthCounts.set('expired-admin', { count: 1, resetTime: now - 1 });
+        roomListCooldowns.set('disconnected', now);
+        roomListCooldowns.set('connected', now);
+        failedAuthAttempts.set('expired-auth', { count: 1, lastAttempt: now - (16 * 60 * 1000) });
+        failedAuthAttempts.set('live-auth', { count: 1, lastAttempt: now });
+
+        startRateLimitCleanup({ sockets: { sockets } });
+        await vi.advanceTimersByTimeAsync(60000);
+        expect([...connectionCounts.keys()]).toEqual(['live-ip']);
+        expect([...eventCounts.keys()]).toEqual(['connected']);
+        expect(chatMessageCounts.size).toBe(0);
+        expect(leaveRoomCounts.size).toBe(0);
+        expect(healthCounts.size).toBe(0);
+        expect(adminMetricsAuthCounts.size).toBe(0);
+        expect([...roomListCooldowns.keys()]).toEqual(['connected']);
+
+        await vi.advanceTimersByTimeAsync(14 * 60 * 1000);
+        expect([...failedAuthAttempts.keys()]).toEqual(['live-auth']);
+        stopRateLimitCleanup();
+        vi.useRealTimers();
+    });
 });
 
 describe('Rate Limit Constants', () => {
diff --git a/tests/e2e/README.md b/tests/e2e/README.md
index 19481f3..09987b6 100644
--- a/tests/e2e/README.md
+++ b/tests/e2e/README.md
@@ -19,6 +19,8 @@ npm run test:e2e:race      # @race scenarios, repeated 20 times
 | :--- | :--- |
 | `detection.spec.mjs` | Runs the shipped `findVideo()` against the fixture pages |
 | `extension.spec.mjs` | Loads `dist/chrome`, injects into a tab, applies remote play/pause/seek |
+| `room-sync.spec.mjs` | Starts a local relay and proves two packed clients, relay restart, and MV3 worker recovery |
+| `popup-accessibility.spec.mjs` | Checks visible control names and keyboard tab activation in the real popup |
 | `fixture-server.mjs` | Static server for the fixtures, with byte-range support for media |
 | `fixtures/pages/` | One page per scenario |
 | `fixtures/media/` | Small generated clips (see below) |
diff --git a/tests/e2e/extension.spec.mjs b/tests/e2e/extension.spec.mjs
index 3892e95..94732b6 100644
--- a/tests/e2e/extension.spec.mjs
+++ b/tests/e2e/extension.spec.mjs
@@ -263,7 +263,7 @@ test('applies remote play, pause and seek to the framed player', async ({ contex
     ).toBeGreaterThan(5);
 });
 
-test('reinjects after the target tab navigates', async ({ context, extensionId, baseURL }) => {
+test('@race reinjects after the target tab navigates', async ({ context, extensionId, baseURL }) => {
     const first = `${baseURL}/pages/iframe-player.html`;
     const page = await context.newPage();
     await page.goto(first);
@@ -286,7 +286,7 @@ test('reinjects after the target tab navigates', async ({ context, extensionId,
     ).toBe('true');
 });
 
-test('re-attaches after the player frame swaps its document', async ({ context, extensionId, baseURL }) => {
+test('@race re-attaches after the player frame swaps its document', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/reloading-frame.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -313,7 +313,7 @@ test('re-attaches after the player frame swaps its document', async ({ context,
     ).toBe('true');
 });
 
-test('re-attaches when a nested player frame swaps its document', async ({ context, extensionId, baseURL }) => {
+test('@race re-attaches when a nested player frame swaps its document', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/nested-frame.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -342,7 +342,7 @@ test('re-attaches when a nested player frame swaps its document', async ({ conte
     ).toBe('true');
 });
 
-test('moves local event listeners after a CSS-only player switch', async ({ context, extensionId, baseURL }) => {
+test('@race moves local event listeners after a CSS-only player switch', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/player-css-switch.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -451,7 +451,7 @@ test('targets a visible nested cross-origin player and keeps top-page debug cont
     });
 });
 
-test('re-elects the visible cross-origin player after an iframe switch', async ({ context, extensionId, baseURL }) => {
+test('@race re-elects the visible cross-origin player after an iframe switch', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/cross-origin-switching.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -476,7 +476,7 @@ test('re-elects the visible cross-origin player after an iframe switch', async (
     expect(await first.locator('video').evaluate(video => video.paused)).toBe(true);
 });
 
-test('immediately adopts and syncs when switching mirrors while first mirror was active and playing', async ({ context, extensionId, baseURL }) => {
+test('@race immediately adopts and syncs when switching mirrors while first mirror was active and playing', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/cross-origin-switching.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -530,7 +530,7 @@ test('keeps commands flowing during continuous player-frame geometry changes', a
     }
 });
 
-test('deactivates media monitors in child frames after a target-tab switch', async ({ context, extensionId, baseURL }) => {
+test('@race deactivates media monitors in child frames after a target-tab switch', async ({ context, extensionId, baseURL }) => {
     const firstUrl = `${baseURL}/pages/cross-origin-nested.html`;
     const secondUrl = `${baseURL}/pages/simple-player.html`;
     const firstPage = await context.newPage();
@@ -580,7 +580,7 @@ test('re-attaches after a selected cross-origin frame navigates', async ({ conte
     expect(state).toMatchObject({ found: true, inIframe: true });
 });
 
-test('discovers a video inserted late inside a cross-origin frame', async ({ context, extensionId, baseURL }) => {
+test('@race discovers a video inserted late inside a cross-origin frame', async ({ context, extensionId, baseURL }) => {
     const url = `${baseURL}/pages/cross-origin-late.html`;
     const page = await context.newPage();
     await page.goto(url);
@@ -668,7 +668,7 @@ test('selects the visible anime player nested behind a same-origin wrapper', asy
     });
 });
 
-test('selects an anime tab before playback and promotes the player once it appears', async ({ context, extensionId, baseURL }) => {
+test('@race selects an anime tab before playback and promotes the player once it appears', async ({ context, extensionId, baseURL }) => {
     // The live case: at selection time the page has no video anywhere, because
     // the host only builds the player when the viewer presses play.
     const url = `${baseURL}/pages/yummy-deferred-player.html`;
@@ -804,7 +804,7 @@ test('controls and adopts a nested player even while the top frame is elected',
     expect(status).toMatchObject({ targetTabId: tabId, targetHasVideo: true });
 });
 
-test('recovers when the adopted player frame is torn down and rebuilt', async ({ context, extensionId, baseURL }) => {
+test('@race recovers when the adopted player frame is torn down and rebuilt', async ({ context, extensionId, baseURL }) => {
     test.setTimeout(90000);
     // Kodik rebuilds its player frame on quality and part changes, which kills
     // the documentId the election is pinned to. The election has to be given up,
diff --git a/tests/e2e/helpers/extension-fixture.mjs b/tests/e2e/helpers/extension-fixture.mjs
index 9ce16c1..91f7806 100644
--- a/tests/e2e/helpers/extension-fixture.mjs
+++ b/tests/e2e/helpers/extension-fixture.mjs
@@ -7,30 +7,83 @@ import { test as base, chromium } from '@playwright/test';
 const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../../..');
 export const extensionPath = path.join(repoRoot, 'dist/chrome');
 
+function isLocalTestUrl(rawUrl) {
+    try {
+        const url = new URL(rawUrl);
+        if (!['http:', 'https:', 'ws:', 'wss:'].includes(url.protocol)) return true;
+        return url.hostname === 'localhost' || url.hostname === '127.0.0.1' || url.hostname === '::1';
+    } catch (_error) {
+        return false;
+    }
+}
+
+export async function launchExtensionContext() {
+    if (!fs.existsSync(path.join(extensionPath, 'manifest.json'))) {
+        throw new Error('dist/chrome is missing. Run: npm run build:extension');
+    }
+    const userDataDir = fs.mkdtempSync(path.join(os.tmpdir(), 'koalasync-e2e-'));
+    let context;
+    try {
+        context = await chromium.launchPersistentContext(userDataDir, {
+            channel: 'chromium',
+            headless: true,
+            args: [
+                `--disable-extensions-except=${extensionPath}`,
+                `--load-extension=${extensionPath}`,
+                '--autoplay-policy=no-user-gesture-required',
+                '--host-resolver-rules=MAP * 0.0.0.0, EXCLUDE localhost, EXCLUDE 127.0.0.1'
+            ]
+        });
+        await context.route('**/*', route => {
+            if (isLocalTestUrl(route.request().url())) return route.continue();
+            return route.abort('blockedbyclient');
+        });
+        if (typeof context.routeWebSocket === 'function') {
+            await context.routeWebSocket(/.*/u, webSocketRoute => {
+                if (isLocalTestUrl(webSocketRoute.url())) {
+                    webSocketRoute.connectToServer();
+                } else {
+                    webSocketRoute.close({ code: 1008, reason: 'External network blocked by E2E harness' });
+                }
+            });
+        }
+        let [worker] = context.serviceWorkers();
+        if (!worker) worker = await context.waitForEvent('serviceworker');
+        const extensionId = worker.url().split('/')[2];
+        return {
+            context,
+            extensionId,
+            async close() {
+                try {
+                    await context.close();
+                } finally {
+                    fs.rmSync(userDataDir, { recursive: true, force: true });
+                }
+            }
+        };
+    } catch (error) {
+        if (context) await context.close().catch(() => {});
+        if (fs.existsSync(userDataDir)) {
+            fs.rmSync(userDataDir, { recursive: true, force: true });
+        }
+        throw error;
+    }
+}
+
 /**
  * A browser with the packed extension loaded, plus its extension id. Each test
  * gets a throwaway profile so storage from one test cannot leak into the next.
  */
 export const test = base.extend({
     context: async ({}, use) => {
-        if (!fs.existsSync(path.join(extensionPath, 'manifest.json'))) {
-            throw new Error('dist/chrome is missing. Run: npm run build:extension');
+        // The headless shell does not run MV3 service workers; the full
+        // Chromium build in new headless mode does.
+        const launched = await launchExtensionContext();
+        try {
+            await use(launched.context);
+        } finally {
+            await launched.close();
         }
-        const userDataDir = fs.mkdtempSync(path.join(os.tmpdir(), 'koalasync-e2e-'));
-        const context = await chromium.launchPersistentContext(userDataDir, {
-            // The headless shell does not run MV3 service workers; the full
-            // Chromium build in new headless mode does.
-            channel: 'chromium',
-            headless: true,
-            args: [
-                `--disable-extensions-except=${extensionPath}`,
-                `--load-extension=${extensionPath}`,
-                '--autoplay-policy=no-user-gesture-required'
-            ]
-        });
-        await use(context);
-        await context.close();
-        fs.rmSync(userDataDir, { recursive: true, force: true });
     },
     extensionId: async ({ context }, use) => {
         let [worker] = context.serviceWorkers();
@@ -85,3 +138,20 @@ export async function readStorage(page, keys) {
 export async function writeStorage(page, values) {
     return page.evaluate(v => chrome.storage.local.set(v), values);
 }
+
+export async function terminateServiceWorker(context, extensionId) {
+    const page = await context.newPage();
+    let session;
+    try {
+        await page.goto(`chrome-extension://${extensionId}/audio-options.html`);
+        session = await context.newCDPSession(page);
+        const { targetInfos } = await session.send('Target.getTargets');
+        const worker = targetInfos.find(target => target.type === 'service_worker'
+            && target.url.startsWith(`chrome-extension://${extensionId}/`));
+        if (!worker) throw new Error(`service worker target missing for ${extensionId}`);
+        await session.send('Target.closeTarget', { targetId: worker.targetId });
+    } finally {
+        if (session) await session.detach().catch(() => {});
+        await page.close().catch(() => {});
+    }
+}
diff --git a/tests/e2e/helpers/relay-process.mjs b/tests/e2e/helpers/relay-process.mjs
new file mode 100644
index 0000000..da5ef5e
--- /dev/null
+++ b/tests/e2e/helpers/relay-process.mjs
@@ -0,0 +1,62 @@
+import { spawn } from 'node:child_process';
+import net from 'node:net';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../../..');
+
+export async function reservePort() {
+    const server = net.createServer();
+    await new Promise((resolve, reject) => {
+        server.once('error', reject);
+        server.listen(0, '127.0.0.1', resolve);
+    });
+    const address = server.address();
+    const port = typeof address === 'object' && address ? address.port : null;
+    await new Promise((resolve, reject) => server.close(error => error ? reject(error) : resolve()));
+    if (!port) throw new Error('failed to reserve relay port');
+    return port;
+}
+
+export async function startRelay(port) {
+    const output = [];
+    const child = spawn(process.execPath, ['server/index.js'], {
+        cwd: repoRoot,
+        env: {
+            ...process.env,
+            PORT: String(port),
+            SERVER_SALT: 'koalasync-e2e-relay-salt-with-more-than-thirty-two-chars'
+        },
+        stdio: ['ignore', 'pipe', 'pipe']
+    });
+    child.stdout.on('data', chunk => output.push(String(chunk)));
+    child.stderr.on('data', chunk => output.push(String(chunk)));
+    const deadline = Date.now() + 15000;
+    while (Date.now() < deadline) {
+        if (child.exitCode !== null) {
+            throw new Error(`relay exited with ${child.exitCode}: ${output.join('')}`);
+        }
+        try {
+            const response = await fetch(`http://127.0.0.1:${port}/health`);
+            if (response.ok) return { child, output };
+        } catch (_error) {
+            // Relay is still starting.
+        }
+        await new Promise(resolve => setTimeout(resolve, 100));
+    }
+    child.kill('SIGTERM');
+    throw new Error(`relay did not become healthy: ${output.join('')}`);
+}
+
+export async function stopRelay(relay) {
+    if (!relay || relay.child.exitCode !== null) return;
+    relay.child.kill('SIGTERM');
+    const stopped = await Promise.race([
+        new Promise(resolve => relay.child.once('exit', () => resolve(true))),
+        new Promise(resolve => setTimeout(() => resolve(false), 7000))
+    ]);
+    if (stopped) return;
+    relay.child.kill('SIGKILL');
+    await new Promise(resolve => relay.child.once('exit', resolve));
+    throw new Error(`relay required SIGKILL: ${relay.output.join('')}`);
+}
diff --git a/tests/e2e/playwright.config.mjs b/tests/e2e/playwright.config.mjs
index 2c91a36..a72f3be 100644
--- a/tests/e2e/playwright.config.mjs
+++ b/tests/e2e/playwright.config.mjs
@@ -12,7 +12,7 @@ export default defineConfig({
     fullyParallel: false,
     forbidOnly: !!process.env.CI,
     retries: 0,
-    reporter: process.env.CI ? 'list' : [['list']],
+    reporter: process.env.CI ? [['list'], ['html', { open: 'never' }]] : [['list']],
     timeout: 30_000,
     expect: { timeout: 10_000 },
     use: {
diff --git a/tests/e2e/popup-accessibility.spec.mjs b/tests/e2e/popup-accessibility.spec.mjs
new file mode 100644
index 0000000..c86e3e6
--- /dev/null
+++ b/tests/e2e/popup-accessibility.spec.mjs
@@ -0,0 +1,29 @@
+import { expect, openPopup, test } from './helpers/extension-fixture.mjs';
+
+test('popup exposes names and keyboard access for every visible control', async ({ context, extensionId }) => {
+    const page = await openPopup(context, extensionId, { openEditor: false });
+    const unnamed = await page.locator('button, input, select, textarea, a[href]').evaluateAll(elements => elements
+        .filter(element => {
+            const style = window.getComputedStyle(element);
+            return !element.disabled && style.display !== 'none' && style.visibility !== 'hidden'
+                && element.getClientRects().length > 0;
+        })
+        .filter(element => {
+            const label = element.getAttribute('aria-label')
+                || element.getAttribute('aria-labelledby')
+                || element.getAttribute('title')
+                || element.labels?.[0]?.textContent
+                || element.textContent;
+            return !String(label || '').trim();
+        })
+        .map(element => `${element.tagName.toLowerCase()}#${element.id || '<no-id>'}`));
+    expect(unnamed).toEqual([]);
+
+    await page.locator('body').press('Tab');
+    await expect(page.locator(':focus')).not.toHaveCount(0);
+    const settingsTab = page.locator('.tab-btn[data-tab="tab-settings"]');
+    await settingsTab.focus();
+    await page.keyboard.press('Enter');
+    await expect(settingsTab).toHaveAttribute('aria-selected', 'true');
+    await expect(page.locator('#tab-settings')).toBeVisible();
+});
diff --git a/tests/e2e/room-sync.spec.mjs b/tests/e2e/room-sync.spec.mjs
new file mode 100644
index 0000000..1e639b8
--- /dev/null
+++ b/tests/e2e/room-sync.spec.mjs
@@ -0,0 +1,117 @@
+import {
+    expect,
+    launchExtensionContext,
+    terminateServiceWorker,
+    test
+} from './helpers/extension-fixture.mjs';
+import { reservePort, startRelay, stopRelay } from './helpers/relay-process.mjs';
+
+// popup.html intentionally performs connection setup. Use a neutral extension
+// page for privileged test messages so opening the test transport cannot race
+// the server settings being exercised.
+async function withExtensionPage(context, extensionId, fn) {
+    const page = await context.newPage();
+    await page.goto(`chrome-extension://${extensionId}/audio-options.html`);
+    try {
+        return await fn(page);
+    } finally {
+        await page.close();
+    }
+}
+
+function getStatus(context, extensionId) {
+    return withExtensionPage(context, extensionId, page => page.evaluate(
+        () => chrome.runtime.sendMessage({ type: 'GET_STATUS' })
+    ));
+}
+
+async function selectTarget(context, extensionId, url) {
+    return withExtensionPage(context, extensionId, page => page.evaluate(async targetUrl => {
+        const [tab] = await chrome.tabs.query({ url: targetUrl });
+        if (!tab) throw new Error(`target tab missing: ${targetUrl}`);
+        const result = await chrome.runtime.sendMessage({ type: 'SET_TARGET_TAB', tabId: tab.id, tabTitle: tab.title });
+        return { tabId: tab.id, result };
+    }, url));
+}
+
+async function connect(context, extensionId, { relayUrl, roomId, username }) {
+    await withExtensionPage(context, extensionId, page => page.evaluate(async settings => {
+        await chrome.storage.local.set({
+            roomId: settings.roomId,
+            password: '',
+            chatKey: '',
+            username: settings.username,
+            useCustomServer: true,
+            serverUrl: settings.relayUrl
+        });
+        await chrome.runtime.sendMessage({ type: 'CONNECT' });
+    }, { relayUrl, roomId, username }));
+}
+
+test('@race synchronizes two packed clients across relay and service-worker restarts', async ({ context, extensionId, baseURL }) => {
+    test.setTimeout(120000);
+    const second = await launchExtensionContext();
+    const port = await reservePort();
+    let relay = await startRelay(port);
+    try {
+        const firstUrl = `${baseURL}/pages/simple-player.html?client=first`;
+        const secondUrl = `${baseURL}/pages/simple-player.html?client=second`;
+        const firstPage = await context.newPage();
+        const secondPage = await second.context.newPage();
+        await Promise.all([firstPage.goto(firstUrl), secondPage.goto(secondUrl)]);
+        await Promise.all([
+            firstPage.waitForFunction(() => window.__fixtureReady === true),
+            secondPage.waitForFunction(() => window.__fixtureReady === true)
+        ]);
+        await selectTarget(context, extensionId, firstUrl);
+        await selectTarget(second.context, second.extensionId, secondUrl);
+
+        const connection = { relayUrl: `ws://127.0.0.1:${port}`, roomId: 'E2E-ROOM-42' };
+        await connect(context, extensionId, { ...connection, username: 'First' });
+        await expect.poll(() => getStatus(context, extensionId)).toMatchObject({
+            status: 'connected',
+            roomId: connection.roomId,
+            peers: [expect.objectContaining({ username: 'First' })]
+        });
+        await connect(second.context, second.extensionId, { ...connection, username: 'Second' });
+        let latestStates = [];
+        try {
+            await expect.poll(async () => {
+                latestStates = await Promise.all([
+                    getStatus(context, extensionId),
+                    getStatus(second.context, second.extensionId)
+                ]);
+                return latestStates.map(state => state.peers.length);
+            }).toEqual([2, 2]);
+        } catch (error) {
+            console.error(`Two-client join diagnostics: ${JSON.stringify(latestStates)}`);
+            console.error(`Relay diagnostics: ${relay.output.join('')}`);
+            throw error;
+        }
+        for (const state of latestStates) expect(state.serverUrl).toBe(connection.relayUrl);
+
+        await firstPage.locator('video').evaluate(video => video.play());
+        await expect.poll(() => secondPage.locator('video').evaluate(video => video.paused)).toBe(false);
+        await firstPage.locator('video').evaluate(video => video.pause());
+        await expect.poll(() => secondPage.locator('video').evaluate(video => video.paused)).toBe(true);
+
+        await stopRelay(relay);
+        relay = null;
+        await expect.poll(() => getStatus(context, extensionId).then(status => status.status))
+            .not.toBe('connected');
+        relay = await startRelay(port);
+        await expect.poll(() => Promise.all([
+            getStatus(context, extensionId),
+            getStatus(second.context, second.extensionId)
+        ]).then(states => states.map(state => state.status)), { timeout: 45000 }).toEqual(['connected', 'connected']);
+
+        await terminateServiceWorker(second.context, second.extensionId);
+        await expect.poll(() => getStatus(second.context, second.extensionId), { timeout: 45000 })
+            .toMatchObject({ status: 'connected', roomId: connection.roomId });
+        await expect.poll(() => getStatus(context, extensionId).then(status => status.peers.length), { timeout: 45000 })
+            .toBe(2);
+    } finally {
+        await stopRelay(relay);
+        await second.close();
+    }
+});
diff --git a/vitest.config.mjs b/vitest.config.mjs
index b2e16be..a5ff824 100644
--- a/vitest.config.mjs
+++ b/vitest.config.mjs
@@ -1,4 +1,5 @@
 import { defineConfig } from 'vitest/config';
+import { VITEST_COVERAGE_INCLUDE } from './scripts/coverage-plan.mjs';
 
 export default defineConfig({
     test: {
@@ -20,12 +21,7 @@ export default defineConfig({
             // by Vitest. Browser entry points and subprocess integration tests
             // have separate E2E/integration gates and must not be reported as
             // zero-coverage unit-test targets.
-            include: [
-                'server/{chat,ops,rate-limiter}.js',
-                'shared/{blacklist,invite-links,names}.js',
-                'extension/{chat-activity,chat-crypto,chat-format,chat-session,chat-wire,episode-utils,host-access,media-frame-target,title-privacy}.js',
-                'scripts/release-artifact-checks.mjs'
-            ],
+            include: VITEST_COVERAGE_INCLUDE,
             exclude: [
                 '**/node_modules/**'
             ],