Reduce CI cost: disable Depot, gate arm64/Tauri PR builds, self-testing CI routing (#7028)

## What

CI cost/routing cleanup. Four changes, each reversible with no code
deleted.

### 1. Disable Depot repo-wide (reversible)
Depot ran on trusted (non-fork) triggers via the `is_fork` output of
`_runner-pick.yml`, driving both the `depot-*` runner selection and the
Depot docker build actions. It's now disabled everywhere behind a single
kill-switch:

- `_runner-pick.yml` gains a dedicated `use_depot` output, forced
`false` via `DEPOT_ENABLED=false`. `is_fork` stays truthful for trust
gating (e.g. `build-enterprise` skipping on forks).
- All `runs-on:` and `USE_DEPOT:` expressions now key off `use_depot`,
so every job falls back to `ubuntu-latest` + buildx.
- `settings.gradle` Depot remote build cache (`cache.depot.dev`) gated
behind `depotCacheEnabled = false`.

**Switch back on:** set `DEPOT_ENABLED=true` in `_runner-pick.yml` (and
`depotCacheEnabled = true` in `settings.gradle`). Depot then reactivates
on trusted triggers exactly as before.

### 2. arm64 PR docker build only on Dockerfile changes
`test-build-docker.yml` was building `linux/amd64,linux/arm64/v8` on
every PR matching the broad `project` filter. With Depot off, the arm64
leg runs under slow QEMU emulation on every code PR. New `dockerfiles`
path filter (`docker/**/Dockerfile*`) gates the arm64 leg: normal code
PRs build amd64 only; PRs that touch a Dockerfile still build amd64 +
arm64. arm64 is still fully exercised on the base-image publish and on
release.

### 3. Tauri PR build -> Linux only, unsigned, deb-only
The PR path built the full 3-OS matrix (Windows + macOS-universal +
Linux), plus the flaky Linux AppImage pass (#6127). PRs now build Linux
only (fastest + cheapest to compile) via a new `minimal` input on
`tauri-build.yml`: Linux deb only, no rpm, no AppImage. The full signed
multi-OS matrix still runs on release, and nightly still warms the Rust
cache with all-OS defaults (unchanged).

Tradeoff: Windows/macOS desktop build breaks are caught by nightly
(all-OS) rather than the introducing PR.

### 4. CI self-testing routing
Editing `build.yml` only matched the `project` filter, so a change to
how e2e / enterprise / tauri / engine jobs are dispatched didn't
actually run those jobs. Added a `ci` anchor (`build.yml` +
`.github/config/.files.yaml`) that every job-gating area filter now
includes, so editing the router or the filter config runs every job.
Also added the orphaned reusable workflows (`e2e-*`,
`frontend-validation`, `docker-compose-tests`, `test-build-docker`,
`check-openapi`, `check-licence`) to their area filters so editing a
reusable workflow self-tests.

## Validation
- All workflow YAML + `.files.yaml` parse; anchor resolution verified
(every job-gating filter resolves to include the `ci` paths).
- Gradle evaluates `settings.gradle` cleanly; `spotlessGradleCheck`
passes.

.github/config/.files.yaml

@@ -1,16 +1,34 @@
+# CI routing infra. Editing the top-level router (build.yml) or this filter
+# config re-runs every area's jobs, so every job-gating filter below includes
+# *ci. That makes a change to how jobs are dispatched actually exercise those
+# jobs (self-testing), instead of a router edit only matching the project filter.
+ci: &ci
+  - .github/workflows/build.yml
+  - .github/config/.files.yaml
+
 build: &build
+  - *ci
   - build.gradle
   - app/(common|core|proprietary|saas)/build.gradle
   - Taskfile.yml
   - .taskfiles/backend.yml
+  - .github/workflows/check-licence.yml
 
 openapi: &openapi
+  - *ci
   - *build
   - app/(common|core|proprietary|saas)/src/main/java/**
+  - .github/workflows/check-openapi.yml
 
 docker-base: &docker-base
   - docker/base/Dockerfile
 
+# Dockerfiles only (base + embedded + unoserver). Gates the slow multi-arch
+# (arm64) leg of the PR docker test build: arm64 is only rebuilt when a
+# Dockerfile itself changes, not on every code PR.
+dockerfiles: &dockerfiles
+  - docker/**/Dockerfile*
+
 docker: &docker
   - docker/embedded/Dockerfile
   - docker/embedded/Dockerfile.fat
@@ -23,13 +41,11 @@ docker: &docker
   - *docker-base
 
 project: &project
+  - *ci
   - app/(common|core|proprietary|saas)/src/(main|test)/java/**
   - *build
   - "app/(common|core|proprietary|saas)/src/(main|test)/resources/**/!(messages_*.properties|*.md)*"
   - exampleYmlFiles/**
-  - gradle/**
-  - libs/**
-  - "testing/**/!(requirements*.txt|requirements*.in)*"
   - *docker
   - *docker-base
   - gradle.properties
@@ -45,8 +61,11 @@ project: &project
   - .taskfiles/docker.yml
   - scripts/db-migration/**
   - .github/workflows/db-migration-test.yml
+  - .github/workflows/docker-compose-tests.yml
+  - .github/workflows/test-build-docker.yml
 
 frontend: &frontend
+  - *ci
   - frontend/**
   - .github/workflows/testdriver.yml
   - testing/**
@@ -63,10 +82,14 @@ frontend: &frontend
   - Taskfile.yml
   - .taskfiles/frontend.yml
   - .taskfiles/e2e.yml
+  - .github/workflows/frontend-validation.yml
+  - .github/workflows/e2e-stubbed.yml
+  - .github/workflows/e2e-live.yml
 
 # Files that affect the Tauri desktop bundle. Gate the multi-OS Tauri build
 # job on changes to any of these.
 tauri: &tauri
+  - *ci
   - frontend/editor/src-tauri/**
   - frontend/editor/src/desktop/**
   - frontend/editor/tsconfig.desktop.vite.json
@@ -81,6 +104,7 @@ tauri: &tauri
 # the engine validation job on changes to engine sources or to the Java
 # tool surfaces it generates models from.
 engine: &engine
+  - *ci
   - engine/**
   - app/(common|core|proprietary|saas)/src/main/java/**
   - .github/workflows/ai-engine.yml
@@ -93,6 +117,7 @@ engine: &engine
 # tasks that drive generation. Deliberately excludes the broad frontend/docker/
 # testing globs, so a CSS-only PR does not boot the backend to rebuild the spec.
 generated-models: &generated-models
+  - *ci
   - *openapi
   - frontend/editor/scripts/generate-tool-api-types.mts
   - frontend/editor/src/core/types/toolApiTypes.ts
@@ -115,6 +140,7 @@ licenses-backend: &licenses-backend
 # Files that can affect premium / enterprise behaviour. Gate the enterprise
 # Playwright job on changes to any of these on PRs.
 proprietary: &proprietary
+  - *ci
   - app/proprietary/**
   - frontend/editor/src/proprietary/**
   - frontend/editor/src/core/tests/enterprise/**

.github/workflows/PR-Auto-Deploy-V2.yml

@@ -29,7 +29,7 @@ jobs:
   check-pr:
     if: (github.event_name == 'pull_request' && github.event.action != 'closed') || github.event_name == 'workflow_dispatch'
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     outputs:
       should_deploy: ${{ steps.decide.outputs.should_deploy }}
       is_fork: ${{ steps.resolve.outputs.is_fork }}
@@ -102,7 +102,7 @@ jobs:
 
   deploy-v2-pr:
     needs: [pick, check-pr]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     if: needs.check-pr.outputs.should_deploy == 'true' && (needs.check-pr.outputs.is_fork == 'false' || needs.check-pr.outputs.allow_fork == 'true')
     # Concurrency control - only one deployment per PR at a time
     concurrency:
@@ -114,7 +114,7 @@ jobs:
       pull-requests: write
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
       # Single source of truth for whether this preview embeds the admin portal:
       # drives the image build-arg and the deployment comment.
@@ -475,7 +475,7 @@ jobs:
   cleanup-v2-deployment:
     if: github.event.action == 'closed'
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       contents: read
       issues: write

.github/workflows/PR-Demo-Comment-with-react.yml

@@ -39,7 +39,7 @@ jobs:
 
   check-comment:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       issues: write
     if: |
@@ -180,13 +180,13 @@ jobs:
 
   deploy-pr:
     needs: [pick, check-comment]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       issues: write
       pull-requests: write
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
 
     steps:
@@ -511,7 +511,7 @@ jobs:
   handle-label-commands:
     if: ${{ github.event.issue.pull_request != null }}
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3

.github/workflows/_runner-pick.yml

@@ -5,6 +5,11 @@ name: _runner-pick
 # can pick a runner class without each one duplicating the 200-char gate
 # expression in their own `runs-on:`.
 #
+# It also owns the single Depot kill-switch (use_depot). Depot is currently
+# disabled repo-wide; downstream jobs gate their Depot runner/build usage on
+# use_depot so nothing has to be deleted to turn Depot off. Flip DEPOT_ENABLED
+# in the decide step to switch Depot back on.
+#
 # Caller pattern:
 #
 #   jobs:
@@ -13,12 +18,15 @@ name: _runner-pick
 #
 #     real-work:
 #       needs: pick
-#       runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-8' }}
+#       runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-8' || 'ubuntu-latest' }}
 #       steps: [...]
 #
-# Output:
-#   is_fork: "true" when the trigger is a pull_request from a fork or an
-#            untrusted author_association, "false" otherwise.
+# Outputs:
+#   is_fork:   "true" when the trigger is a pull_request from a fork or an
+#              untrusted author_association, "false" otherwise. Use this for
+#              trust gating (skipping secret-dependent jobs on forks).
+#   use_depot: "true" when downstream jobs should use Depot runners/builders.
+#              Currently forced "false" (Depot disabled repo-wide).
 
 on:
   workflow_call:
@@ -26,6 +34,9 @@ on:
       is_fork:
         description: '"true" if the trigger is an untrusted fork PR.'
         value: ${{ jobs.pick.outputs.is_fork }}
+      use_depot:
+        description: '"true" when downstream jobs should use Depot. Currently forced off.'
+        value: ${{ jobs.pick.outputs.use_depot }}
 
 permissions:
   contents: read
@@ -36,6 +47,7 @@ jobs:
     timeout-minutes: 1
     outputs:
       is_fork: ${{ steps.decide.outputs.is_fork }}
+      use_depot: ${{ steps.decide.outputs.use_depot }}
     steps:
       - name: Harden the runner (Audit all outbound calls)
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3
@@ -50,21 +62,33 @@ jobs:
           AUTHOR_ASSOC: ${{ github.event.pull_request.author_association }}
         run: |
           set -eu
+
+          # Depot kill-switch. Depot is disabled repo-wide: no job uses Depot
+          # runners or the Depot build actions while this is false. All the
+          # Depot wiring is left in place - set DEPOT_ENABLED=true to switch it
+          # back on (it then activates on trusted, non-fork triggers as before).
+          DEPOT_ENABLED=false
+
           if [ -z "${PR_NUMBER:-}" ]; then
             # Not a pull_request event at all (push, schedule, workflow_dispatch,
             # workflow_call from a non-PR trigger) -> trusted by default.
-            echo "is_fork=false" >> "$GITHUB_OUTPUT"
-            exit 0
+            is_fork=false
+          elif [ "${HEAD_REPO_FORK}" = "true" ]; then
+            is_fork=true
+          else
+            case "${AUTHOR_ASSOC}" in
+              OWNER|MEMBER|COLLABORATOR) is_fork=false ;;
+              *) is_fork=true ;;
+            esac
           fi
-          if [ "${HEAD_REPO_FORK}" = "true" ]; then
-            echo "is_fork=true" >> "$GITHUB_OUTPUT"
-            exit 0
+
+          # Depot only ever ran on trusted triggers, so gate it on both the
+          # kill-switch and is_fork.
+          if [ "${DEPOT_ENABLED}" = "true" ] && [ "${is_fork}" = "false" ]; then
+            use_depot=true
+          else
+            use_depot=false
           fi
-          case "${AUTHOR_ASSOC}" in
-            OWNER|MEMBER|COLLABORATOR)
-              echo "is_fork=false" >> "$GITHUB_OUTPUT"
-              ;;
-            *)
-              echo "is_fork=true" >> "$GITHUB_OUTPUT"
-              ;;
-          esac
+
+          echo "is_fork=${is_fork}" >> "$GITHUB_OUTPUT"
+          echo "use_depot=${use_depot}" >> "$GITHUB_OUTPUT"

.github/workflows/backend-build.yml

@@ -24,7 +24,7 @@ jobs:
 
   build:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-8' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-8' || 'ubuntu-latest' }}
     env:
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     strategy:

.github/workflows/build-enterprise.yml

@@ -54,7 +54,7 @@ jobs:
     # (nor DEPOT_TOKEN), so the suite can't boot premium and would fail. See the
     # header comment. GitHub reports the skipped reusable workflow as success.
     if: needs.pick.outputs.is_fork != 'true'
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') || 'ubuntu-latest' }}
     timeout-minutes: 45
     env:
       PREMIUM_KEY: ${{ secrets.PREMIUM_KEY_ENTERPRISE }}

.github/workflows/build.yml

@@ -41,6 +41,7 @@ jobs:
       openapi: ${{ steps.changes.outputs.openapi }}
       frontend: ${{ steps.changes.outputs.frontend }}
       docker-base: ${{ steps.changes.outputs.docker-base }}
+      dockerfiles: ${{ steps.changes.outputs.dockerfiles }}
       tauri: ${{ steps.changes.outputs.tauri }}
       engine: ${{ steps.changes.outputs.engine }}
       generated-models: ${{ steps.changes.outputs.generated-models }}
@@ -153,6 +154,7 @@ jobs:
     secrets: inherit
     with:
       docker-base-changed: ${{ needs.files-changed.outputs.docker-base }}
+      dockerfiles-changed: ${{ needs.files-changed.outputs.dockerfiles }}
 
   tauri-build:
     if: needs.files-changed.outputs.tauri == 'true'
@@ -162,6 +164,13 @@ jobs:
       pull-requests: write
     uses: ./.github/workflows/tauri-build.yml
     secrets: inherit
+    # PR smoke build: Linux only (fastest + cheapest to compile), unsigned,
+    # deb-only, no AppImage. The full signed multi-OS matrix runs on release;
+    # nightly still warms the Rust cache with all-OS defaults.
+    with:
+      platform: linux
+      sign: false
+      minimal: true
 
   ai-engine:
     if: needs.files-changed.outputs.engine == 'true'

.github/workflows/check-openapi.yml

@@ -15,7 +15,7 @@ jobs:
 
   check-generate-openapi-docs:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     env:
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     steps:

.github/workflows/coverage-aggregate.yml

@@ -34,7 +34,7 @@ jobs:
 
   aggregate:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     timeout-minutes: 15
     steps:
       - name: Harden Runner

.github/workflows/db-migration-test.yml

@@ -17,7 +17,7 @@ jobs:
 
   migration-test:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-8' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-8' || 'ubuntu-latest' }}
     timeout-minutes: 30
     env:
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}

.github/workflows/deploy-on-v2-commit.yml

@@ -15,7 +15,7 @@ jobs:
 
   deploy-v2-on-push:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     concurrency:
       group: deploy-v2-push-V2
       cancel-in-progress: true
@@ -23,7 +23,7 @@ jobs:
       contents: read
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
 
     steps:

.github/workflows/docker-compose-tests.yml

@@ -26,7 +26,7 @@ jobs:
 
   docker-compose-tests:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '4') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '4') || 'ubuntu-latest' }}
     permissions:
       actions: write
       contents: read

.github/workflows/e2e-live.yml

@@ -21,7 +21,7 @@ jobs:
 
   playwright-e2e-live:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') || 'ubuntu-latest' }}
     timeout-minutes: 30
     steps:
       - name: Harden Runner

.github/workflows/e2e-stubbed.yml

@@ -21,7 +21,7 @@ jobs:
 
   playwright-e2e:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') || 'ubuntu-latest' }}
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3

.github/workflows/frontend-backend-licenses-update.yml

@@ -25,7 +25,7 @@ jobs:
   files-changed:
     name: detect what files changed
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     timeout-minutes: 3
     outputs:
       licenses-frontend: ${{ steps.changes.outputs.licenses-frontend }}
@@ -49,7 +49,7 @@ jobs:
     if: needs.files-changed.outputs.licenses-frontend == 'true'
     name: Generate Frontend License Report
     needs: [pick, files-changed]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       contents: write
       pull-requests: write
@@ -320,7 +320,7 @@ jobs:
     if: needs.files-changed.outputs.licenses-backend == 'true'
     needs: [pick, files-changed]
     name: Generate Backend License Report
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       contents: write
       pull-requests: write

.github/workflows/frontend-validation.yml

@@ -16,7 +16,7 @@ jobs:
 
   frontend-validation:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3

.github/workflows/multiOSReleases.yml

@@ -42,7 +42,7 @@ jobs:
   determine-matrix:
     if: ${{ vars.CI_PROFILE != 'lite' }}
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     outputs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
       version: ${{ steps.versionNumber.outputs.versionNumber }}
@@ -113,7 +113,7 @@ jobs:
 
   build-jars:
     needs: [pick, determine-matrix]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     env:
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     strategy:
@@ -639,7 +639,7 @@ jobs:
 
   collect-and-release:
     needs: [pick, determine-matrix, build, build-jars]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       contents: write
     steps:

.github/workflows/nightly.yml

@@ -19,7 +19,7 @@ jobs:
   playwright-all-browsers:
     name: Playwright (chromium + firefox + webkit)
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     steps:
       - name: Harden the runner (Audit all outbound calls)
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3

.github/workflows/swagger.yml

@@ -28,7 +28,7 @@ jobs:
   push:
     if: ${{ vars.CI_PROFILE != 'lite' }}
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     env:
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     steps:

.github/workflows/tauri-build.yml

@@ -21,6 +21,11 @@ on:
         required: false
         type: boolean
         default: true
+      minimal:
+        description: "Fast smoke build: Linux deb only, skip rpm and the flaky AppImage pass. Used by PR builds."
+        required: false
+        type: boolean
+        default: false
   workflow_dispatch:
     inputs:
       platform:
@@ -38,6 +43,11 @@ on:
         required: false
         default: true
         type: boolean
+      minimal:
+        description: "Fast smoke build: Linux deb only, skip rpm and the flaky AppImage pass."
+        required: false
+        default: false
+        type: boolean
 
 permissions:
   contents: read
@@ -386,10 +396,10 @@ jobs:
         with:
           projectPath: ./frontend/editor
           tauriScript: npx tauri
-          # Linux: build deb+rpm only here. AppImage runs in its own
-          # continue-on-error step below so its persistent linuxdeploy
-          # failure (#6127 onwards) does not tank deb/rpm uploads.
-          args: ${{ matrix.platform == 'ubuntu-22.04' && '--bundles deb,rpm' || matrix.args }}
+          # Linux: build deb+rpm only here (deb-only on minimal smoke builds).
+          # AppImage runs in its own continue-on-error step below so its
+          # persistent linuxdeploy failure (#6127 onwards) does not tank uploads.
+          args: ${{ matrix.platform == 'ubuntu-22.04' && (inputs.minimal && '--bundles deb' || '--bundles deb,rpm') || matrix.args }}
 
       - name: Build Tauri app (unsigned)
         if: ${{ !inputs.sign }}
@@ -406,15 +416,16 @@ jobs:
         with:
           projectPath: ./frontend/editor
           tauriScript: npx tauri
-          # Linux: build deb+rpm only here. AppImage runs in its own
-          # continue-on-error step below so its persistent linuxdeploy
-          # failure (#6127 onwards) does not tank deb/rpm uploads.
-          args: ${{ matrix.platform == 'ubuntu-22.04' && '--bundles deb,rpm' || matrix.args }}
+          # Linux: build deb+rpm only here (deb-only on minimal smoke builds).
+          # AppImage runs in its own continue-on-error step below so its
+          # persistent linuxdeploy failure (#6127 onwards) does not tank uploads.
+          args: ${{ matrix.platform == 'ubuntu-22.04' && (inputs.minimal && '--bundles deb' || '--bundles deb,rpm') || matrix.args }}
 
       # AppImage is decoupled so its linuxdeploy run gets a fresh process
       # (rpm scratch state torn down) and its failure can't tank deb/rpm.
+      # Skipped on minimal smoke builds (flaky + slow, deb is enough to verify).
       - name: Build Tauri app (Linux AppImage)
-        if: matrix.platform == 'ubuntu-22.04'
+        if: matrix.platform == 'ubuntu-22.04' && !inputs.minimal
         continue-on-error: true
         uses: tauri-apps/tauri-action@84b9d35b5fc46c1e45415bdb6144030364f7ebc5 # v0.6.2
         env:

.github/workflows/test-build-docker.yml

@@ -12,6 +12,11 @@ on:
         required: false
         type: string
         default: "false"
+      dockerfiles-changed:
+        description: "Whether any Dockerfile changed (forwarded from files-changed). Gates the slow arm64 build leg."
+        required: false
+        type: string
+        default: "false"
       depot_cores:
         description: "Depot runner vCPU count (used in runs-on). Override for benchmarking."
         required: false
@@ -41,12 +46,12 @@ jobs:
   # `task backend:build:ci` produce equivalent JARs (verify before wiring).
   test-build-docker-images:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') || 'ubuntu-latest' }}
     permissions:
       contents: read
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' && inputs.docker-base-changed != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' && inputs.docker-base-changed != 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     strategy:
       fail-fast: false
@@ -146,13 +151,22 @@ jobs:
         # GITHUB_EVENT_NAME is already provided by the runner.
         env:
           DOCKER_BASE_CHANGED: ${{ inputs.docker-base-changed }}
+          DOCKERFILES_CHANGED: ${{ inputs.dockerfiles-changed }}
         run: |
           if [ "$GITHUB_EVENT_NAME" = "pull_request" ] && [ "$DOCKER_BASE_CHANGED" = "true" ]; then
+            # Base Dockerfile changed: build against the locally-built base,
+            # which only exists for amd64.
             echo "base_image=stirling-pdf-base:pr-test" >> "$GITHUB_OUTPUT"
             echo "platforms=linux/amd64" >> "$GITHUB_OUTPUT"
-          else
+          elif [ "$DOCKERFILES_CHANGED" = "true" ]; then
+            # A Dockerfile changed: also verify the arm64 build (slow QEMU leg).
             echo "base_image=stirlingtools/stirling-pdf-base:latest" >> "$GITHUB_OUTPUT"
             echo "platforms=linux/amd64,linux/arm64/v8" >> "$GITHUB_OUTPUT"
+          else
+            # No Dockerfile change: amd64 only. arm64 is exercised on the base
+            # image publish and on release, not on every code PR.
+            echo "base_image=stirlingtools/stirling-pdf-base:latest" >> "$GITHUB_OUTPUT"
+            echo "platforms=linux/amd64" >> "$GITHUB_OUTPUT"
           fi
 
       # Base-changed PRs build the embedded image with the local docker driver
@@ -214,12 +228,12 @@ jobs:
 
   test-build-unoserver-image:
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && format('depot-ubuntu-24.04-{0}', inputs.depot_cores || '8') || 'ubuntu-latest' }}
     permissions:
       contents: read
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' && inputs.docker-base-changed != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' && inputs.docker-base-changed != 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     steps:
       - name: Harden Runner

.github/workflows/testdriver.yml

@@ -26,12 +26,12 @@ jobs:
   deploy:
     if: ${{ vars.CI_PROFILE != 'lite' }}
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     permissions:
       contents: read
       id-token: write
     env:
-      USE_DEPOT: ${{ needs.pick.outputs.is_fork != 'true' }}
+      USE_DEPOT: ${{ needs.pick.outputs.use_depot == 'true' }}
       DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
     steps:
       - name: Harden Runner
@@ -154,7 +154,7 @@ jobs:
     if: always()
     name: detect what files changed
     needs: pick
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     timeout-minutes: 3
     outputs:
       frontend: ${{ steps.changes.outputs.frontend }}
@@ -175,7 +175,7 @@ jobs:
   test:
     if: needs.files-changed.outputs.frontend == 'true'
     needs: [pick, deploy, files-changed]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@ab7a9404c0f3da075243ca237b5fac12c98deaa5 # v2.19.3
@@ -209,7 +209,7 @@ jobs:
 
   cleanup:
     needs: [pick, deploy, test]
-    runs-on: ${{ needs.pick.outputs.is_fork == 'true' && 'ubuntu-latest' || 'depot-ubuntu-24.04-4' }}
+    runs-on: ${{ needs.pick.outputs.use_depot == 'true' && 'depot-ubuntu-24.04-4' || 'ubuntu-latest' }}
     if: always()
 
     steps:

settings.gradle

@@ -23,15 +23,17 @@ plugins {
     id 'org.gradle.toolchains.foojay-resolver-convention' version '1.0.0'
 }
 
-// Depot remote build cache. Silently no-ops when DEPOT_TOKEN is absent
-// (local dev without depot login, and fork PRs where GitHub hides secrets),
-// so contributors without Depot access still build fine on local cache only.
+// Depot remote build cache. Disabled repo-wide via depotCacheEnabled below;
+// flip it back to true to re-enable. Even when enabled it silently no-ops
+// without DEPOT_TOKEN (local dev without depot login, and fork PRs where
+// GitHub hides secrets), so contributors build fine on local cache only.
 buildCache {
+    def depotCacheEnabled = false
     def depotToken = System.getenv('DEPOT_TOKEN')
     local {
         enabled = true
     }
-    if (depotToken) {
+    if (depotCacheEnabled && depotToken) {
         remote(HttpBuildCache) {
             url = 'https://cache.depot.dev'
             enabled = true