diff --git a/.github/actions/setup-apt-mirrors/action.yml b/.github/actions/setup-apt-mirrors/action.yml
index 5beff201d188e..ec1df94c0c04c 100644
--- a/.github/actions/setup-apt-mirrors/action.yml
+++ b/.github/actions/setup-apt-mirrors/action.yml
@@ -5,7 +5,7 @@ runs:
   steps:
     - shell: bash
       run: |
-        # Replace the existing Blacksmith mirror list as well as direct sources.
+        # Replace GitHub and Blacksmith mirror lists as well as direct sources.
         printf '%s\tpriority:%s\n' \
           https://archive.ubuntu.com/ubuntu 1 \
           https://mirrors.edge.kernel.org/ubuntu 2 \
@@ -15,7 +15,7 @@ runs:
         # APT's mirror transport retries each file against the next server.
         sudo find /etc/apt -maxdepth 2 -type f \( -name '*.list' -o -name '*.sources' \) \
           -exec sed -i -E \
-          's#https?://(([^/]+\.)?archive|security)\.ubuntu\.com/ubuntu/?#mirror+file:/etc/apt/blacksmith-ubuntu-mirrors.txt#g' {} +
+          's#https?://(([^/]+\.)?archive|security)\.ubuntu\.com/ubuntu/?|mirror\+file:/etc/apt/apt-mirrors\.txt#mirror+file:/etc/apt/blacksmith-ubuntu-mirrors.txt#g' {} +
 
         # Move on to a fallback before an unreachable server exhausts the job.
         printf '%s\n' 'Acquire::http::Timeout "15";' 'Acquire::https::Timeout "15";' \
diff --git a/.github/scripts/fork-dependencies.test.cjs b/.github/scripts/fork-dependencies.test.cjs
new file mode 100644
index 0000000000000..a73c3bf74514f
--- /dev/null
+++ b/.github/scripts/fork-dependencies.test.cjs
@@ -0,0 +1,132 @@
+const assert = require("node:assert/strict");
+const { spawnSync } = require("node:child_process");
+const fs = require("node:fs");
+const os = require("node:os");
+const path = require("node:path");
+const test = require("node:test");
+
+function fixture(t) {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "t3-fork-dependencies-"));
+  t.after(() => fs.rmSync(root, { recursive: true, force: true }));
+  return root;
+}
+
+function run(script, env) {
+  const result = spawnSync(
+    "bash",
+    ["--noprofile", "--norc", "-e", "-o", "pipefail", "-c", script],
+    {
+      encoding: "utf8",
+      env: { ...process.env, ...env },
+    },
+  );
+  assert.ifError(result.error);
+  return result;
+}
+
+test("APT failover covers GitHub mirror lists, direct Ubuntu sources, and existing Blacksmith sources", (t) => {
+  const root = fixture(t);
+  fs.mkdirSync(path.join(root, "sources.list.d"));
+  fs.mkdirSync(path.join(root, "apt.conf.d"));
+  const sources = {
+    "sources.list": [
+      "deb http://azure.archive.ubuntu.com/ubuntu/ noble main",
+      "deb https://archive.ubuntu.com/ubuntu noble-updates main",
+      "deb http://security.ubuntu.com/ubuntu/ noble-security main",
+      "deb https://packages.example.invalid/ubuntu noble main",
+    ].join("\n"),
+    "sources.list.d/ubuntu.sources":
+      "Types: deb\nURIs: mirror+file:/etc/apt/apt-mirrors.txt\nSuites: noble noble-updates\nComponents: main universe\n",
+    "sources.list.d/blacksmith.sources":
+      "Types: deb\nURIs: mirror+file:/etc/apt/blacksmith-ubuntu-mirrors.txt\nSuites: noble\nComponents: main\n",
+  };
+  for (const [file, contents] of Object.entries(sources)) {
+    fs.writeFileSync(path.join(root, file), contents);
+  }
+  const action = fs.readFileSync(
+    path.join(__dirname, "../actions/setup-apt-mirrors/action.yml"),
+    "utf8",
+  );
+  const step = action.match(/      run: \|\n([\s\S]+)/);
+  assert.ok(step);
+  const script =
+    `sudo() {
+      local arg
+      local args=()
+      for arg in "$@"; do
+        if [[ "$arg" == /etc/apt* ]]; then
+          args+=("$FIXTURE_APT\${arg#/etc/apt}")
+        else
+          args+=("$arg")
+        fi
+      done
+      "\${args[@]}"
+    }\n` + step[1].replace(/^        /gm, "");
+  const env = { FIXTURE_APT: root.replaceAll("\\", "/") };
+  const result = run(script, env);
+  assert.equal(result.status, 0, result.stderr);
+  const mirror = "mirror+file:/etc/apt/blacksmith-ubuntu-mirrors.txt";
+  assert.equal(
+    fs.readFileSync(path.join(root, "sources.list"), "utf8"),
+    [
+      `deb ${mirror} noble main`,
+      `deb ${mirror} noble-updates main`,
+      `deb ${mirror} noble-security main`,
+      "deb https://packages.example.invalid/ubuntu noble main",
+    ].join("\n"),
+  );
+  assert.equal(
+    fs.readFileSync(path.join(root, "sources.list.d/ubuntu.sources"), "utf8"),
+    sources["sources.list.d/ubuntu.sources"].replace(
+      "mirror+file:/etc/apt/apt-mirrors.txt",
+      mirror,
+    ),
+  );
+  assert.equal(
+    fs.readFileSync(path.join(root, "sources.list.d/blacksmith.sources"), "utf8"),
+    sources["sources.list.d/blacksmith.sources"],
+  );
+  assert.equal(run(script, env).status, 0);
+});
+
+test("fork browser dependency checks avoid unnecessary APT installs without masking failures", (t) => {
+  const scripts = ["fork-nightly.yml", "fork-pr.yml"].map((file) => {
+    const workflow = fs.readFileSync(path.join(__dirname, "../workflows", file), "utf8");
+    const step = workflow.match(
+      /- name: Install missing Chromium system dependencies\n        run: \|\n((?:          .*\n|\n)+)/,
+    );
+    assert.ok(step, `${file} must check cached Chromium dependencies`);
+    return step[1].replace(/^          /gm, "");
+  });
+  assert.equal(scripts[0], scripts[1]);
+  for (const { browser = true, libraries = "", lddExit = 0, installExit = 0, status, installs } of [
+    { status: 0, installs: false },
+    { libraries: "libnss3.so => not found", status: 0, installs: true },
+    { browser: false, status: 1, installs: false },
+    { lddExit: 2, status: 2, installs: false },
+    { libraries: "libnss3.so => not found", installExit: 100, status: 100, installs: true },
+  ]) {
+    const root = fixture(t);
+    const cache = path.join(root, ".cache", "ms-playwright", "chromium_headless_shell-1234");
+    fs.mkdirSync(cache, { recursive: true });
+    if (browser) fs.writeFileSync(path.join(cache, "chrome-headless-shell"), "");
+    const calls = path.join(root, "calls");
+    const result = run(
+      `ldd() { printf '%s\\n' "$FIXTURE_LIBRARIES"; return "$FIXTURE_LDD_EXIT"; }
+       node() { printf '%s\\n' "$*" >> "$FIXTURE_CALLS"; return "$FIXTURE_INSTALL_EXIT"; }\n` +
+        scripts[0],
+      {
+        HOME: root.replaceAll("\\", "/"),
+        FIXTURE_CALLS: calls.replaceAll("\\", "/"),
+        FIXTURE_LIBRARIES: libraries,
+        FIXTURE_LDD_EXIT: String(lddExit),
+        FIXTURE_INSTALL_EXIT: String(installExit),
+      },
+    );
+    assert.equal(result.status, status, result.stderr);
+    assert.equal(
+      fs.existsSync(calls) ? fs.readFileSync(calls, "utf8") : "",
+      installs ? "apps/web/node_modules/playwright/cli.js install-deps chromium\n" : "",
+    );
+  }
+});
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6f75c92562d03..b8717f97770f1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
   # open: if the diff cannot be resolved, everything runs.
   changes:
     name: Changes
-    runs-on: blacksmith-2vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-2vcpu-ubuntu-2404' }}
     timeout-minutes: 5
     outputs:
       typecheck: ${{ steps.detect.outputs.typecheck }}
@@ -64,7 +64,7 @@ jobs:
       contents: read
       id-token: write
     name: Lint
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     timeout-minutes: 10
     steps:
       - name: Checkout
@@ -120,7 +120,7 @@ jobs:
     name: Build and Typecheck
     needs: changes
     if: ${{ !cancelled() && (needs.changes.outputs.build != 'false' || needs.changes.outputs.typecheck != 'false') }}
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     timeout-minutes: 10
     steps:
       - name: Checkout
@@ -275,7 +275,7 @@ jobs:
     name: Test
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.test != 'false' }}
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     timeout-minutes: 10
     steps:
       - name: Checkout
@@ -365,7 +365,7 @@ jobs:
     name: Test Web ${{ matrix.shard }}
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.test_web != 'false' }}
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     timeout-minutes: 10
     strategy:
       fail-fast: false
@@ -403,6 +403,9 @@ jobs:
         if: steps.chromium_cache.outputs.cache-hit != 'true'
         run: node apps/web/node_modules/playwright/cli.js install --only-shell chromium
 
+      - uses: ./.github/actions/setup-apt-mirrors
+        if: github.repository == 'amv146/t3code'
+
       - name: Install missing Chromium system dependencies
         run: |
           browser=$(find "$HOME/.cache/ms-playwright" -name chrome-headless-shell -type f -print -quit)
@@ -427,7 +430,7 @@ jobs:
       contents: read
       id-token: write
     name: Test Server ${{ matrix.shard }}
-    runs-on: blacksmith-4vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-4vcpu-ubuntu-2404' }}
     # Shards take 2-5 minutes. When the shared task cache throttles reads, each
     # failed fetch stalls vp for 15-90s, which pushed shards past 10 minutes.
     timeout-minutes: 20
@@ -478,6 +481,9 @@ jobs:
         if: steps.changes.outputs.test_server != 'false' && steps.chromium_cache.outputs.cache-hit != 'true'
         run: node apps/server/node_modules/playwright-core/cli.js install --only-shell chromium
 
+      - uses: ./.github/actions/setup-apt-mirrors
+        if: github.repository == 'amv146/t3code' && steps.changes.outputs.test_server != 'false'
+
       - name: Install missing Chromium system dependencies
         if: steps.changes.outputs.test_server != 'false'
         run: |
@@ -553,7 +559,7 @@ jobs:
     name: Rust
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.rust != 'false' }}
-    runs-on: blacksmith-4vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-4vcpu-ubuntu-2404' }}
     timeout-minutes: 10
     steps:
       - name: Checkout
@@ -586,7 +592,7 @@ jobs:
     name: Mobile Native Static Analysis
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.mobile_native != 'false' }}
-    runs-on: blacksmith-6vcpu-macos-26
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'macos-26' || 'blacksmith-6vcpu-macos-26' }}
     timeout-minutes: 10
     steps:
       - name: Checkout
@@ -619,7 +625,7 @@ jobs:
     name: Release Smoke
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.release_smoke != 'false' }}
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     timeout-minutes: 15
     steps:
       - name: Checkout
@@ -659,7 +665,7 @@ jobs:
         mobile_native_static_analysis,
         release_smoke,
       ]
-    runs-on: blacksmith-2vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-2vcpu-ubuntu-2404' }}
     timeout-minutes: 5
     steps:
       - name: Require every job to pass
diff --git a/.github/workflows/fork-nightly.yml b/.github/workflows/fork-nightly.yml
index 065f97342d887..043abd6af77cd 100644
--- a/.github/workflows/fork-nightly.yml
+++ b/.github/workflows/fork-nightly.yml
@@ -42,7 +42,7 @@ jobs:
           fetch-depth: 0
           token: ${{ secrets.FORK_SYNC_TOKEN }}
       - name: Check sync logic
-        run: node --test .github/scripts/fork-nightly.test.cjs
+        run: node --test .github/scripts/fork-nightly.test.cjs .github/scripts/fork-dependencies.test.cjs
       - name: Merge the latest published upstream nightly
         id: prepare
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
@@ -71,13 +71,32 @@ jobs:
             !/.repos/
           sparse-checkout-cone-mode: false
       - uses: ./.github/actions/setup-ci-deps
+      - uses: ./.github/actions/setup-apt-mirrors
+      - name: Resolve Playwright version
+        id: playwright_version
+        run: echo "version=$(node -p "require('./apps/web/node_modules/playwright/package.json').version")" >> "$GITHUB_OUTPUT"
+      - name: Cache Chromium
+        id: chromium_cache
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-shell-${{ runner.os }}-${{ runner.arch }}-${{ steps.playwright_version.outputs.version }}
       - name: Install Chromium for changed browser tests
-        run: node apps/web/node_modules/playwright/cli.js install --with-deps --only-shell chromium
+        if: steps.chromium_cache.outputs.cache-hit != 'true'
+        run: node apps/web/node_modules/playwright/cli.js install --only-shell chromium
+      - name: Install missing Chromium system dependencies
+        run: |
+          browser=$(find "$HOME/.cache/ms-playwright" -name chrome-headless-shell -type f -print -quit)
+          test -n "$browser"
+          libraries=$(ldd "$browser")
+          if grep '=> not found' <<< "$libraries"; then
+            node apps/web/node_modules/playwright/cli.js install-deps chromium
+          fi
       - name: Check fork changes against the upstream nightly
         env:
           UPSTREAM_SHA: ${{ needs.sync.outputs.upstream_sha }}
         run: |
-          node --test .github/scripts/fork-nightly.test.cjs
+          node --test .github/scripts/fork-nightly.test.cjs .github/scripts/fork-dependencies.test.cjs
           vp run check:changed "$UPSTREAM_SHA"
       - name: Load public T3 Connect configuration
         id: config
@@ -148,6 +167,7 @@ jobs:
           cargo build --locked --release --manifest-path native/resource-monitor/Cargo.toml --target x86_64-unknown-linux-gnu
           mkdir -p "$RUNNER_TEMP/cli-resource-monitor/linux-x64"
           cp native/resource-monitor/target/x86_64-unknown-linux-gnu/release/t3-resource-monitor "$RUNNER_TEMP/cli-resource-monitor/linux-x64/"
+      - uses: ./.github/actions/setup-apt-mirrors
       - name: Install archive build libraries
         run: sudo apt-get update && sudo apt-get install -y patchelf libsecret-1-dev pkg-config
       - name: Build matching WSL runtime
diff --git a/.github/workflows/fork-pr.yml b/.github/workflows/fork-pr.yml
index 86cfa0095fdd5..4e07f2ccd88fa 100644
--- a/.github/workflows/fork-pr.yml
+++ b/.github/workflows/fork-pr.yml
@@ -34,8 +34,27 @@ jobs:
             !/.repos/
           sparse-checkout-cone-mode: false
       - uses: ./.github/actions/setup-ci-deps
+      - uses: ./.github/actions/setup-apt-mirrors
+      - name: Resolve Playwright version
+        id: playwright_version
+        run: echo "version=$(node -p "require('./apps/web/node_modules/playwright/package.json').version")" >> "$GITHUB_OUTPUT"
+      - name: Cache Chromium
+        id: chromium_cache
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-shell-${{ runner.os }}-${{ runner.arch }}-${{ steps.playwright_version.outputs.version }}
       - name: Install Chromium for changed browser tests
-        run: node apps/web/node_modules/playwright/cli.js install --with-deps --only-shell chromium
+        if: steps.chromium_cache.outputs.cache-hit != 'true'
+        run: node apps/web/node_modules/playwright/cli.js install --only-shell chromium
+      - name: Install missing Chromium system dependencies
+        run: |
+          browser=$(find "$HOME/.cache/ms-playwright" -name chrome-headless-shell -type f -print -quit)
+          test -n "$browser"
+          libraries=$(ldd "$browser")
+          if grep '=> not found' <<< "$libraries"; then
+            node apps/web/node_modules/playwright/cli.js install-deps chromium
+          fi
       - name: Check changes against the target branch
         env:
           BASE: ${{ github.event.pull_request.base.sha || format('origin/{0}', inputs.base) }}
diff --git a/.github/workflows/mobile-fingerprint-check.yml b/.github/workflows/mobile-fingerprint-check.yml
index 9fabb3a5f2ad2..62e905d45656c 100644
--- a/.github/workflows/mobile-fingerprint-check.yml
+++ b/.github/workflows/mobile-fingerprint-check.yml
@@ -25,7 +25,7 @@ concurrency:
 jobs:
   fingerprint:
     name: Native fingerprint diff
-    runs-on: blacksmith-8vcpu-ubuntu-2404
+    runs-on: ${{ github.repository == 'amv146/t3code' && 'ubuntu-24.04' || 'blacksmith-8vcpu-ubuntu-2404' }}
     permissions:
       contents: read
     env: