feat: add early trigger check and caching to CI workflows

Before this change the workflows installed ffmpeg (~94 MB, 100 packages)
and Playwright Chromium on every run, even when the trigger config
(on-demand / smart mode) would decide to skip the pipeline.

Changes:
- Add packages/action/src/check.ts: lightweight pre-check entrypoint
  that evaluates the trigger and writes a `should-run` step output.
  Mirrors the early logic in index.ts but exits before any heavy work.
- Update build script to also compile check.ts → dist/check.js.
- demo.yml: run the trigger check immediately after `pnpm install`,
  then gate ffmpeg, Playwright, app start, and the action itself with
  `if: steps.check.outputs.should-run == 'true'`.
  Also adds pnpm store caching and Playwright browser caching.
- ci.yml: add pnpm store caching to both jobs, add Playwright browser
  caching to the integration-tests job.

On skipped runs the job now exits after a few seconds of lightweight
setup. On cache-hit runs the heavy installs are also significantly
faster.

https://claude.ai/code/session_014X9H6DRMx8hHT9En1GXDGt

Author: claude

.github/workflows/ci.yml

@@ -14,6 +14,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: '20'
+          cache: 'pnpm'
 
       - uses: pnpm/action-setup@v4
 
@@ -32,6 +33,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: '20'
+          cache: 'pnpm'
 
       - uses: pnpm/action-setup@v4
 
@@ -41,6 +43,13 @@ jobs:
       - name: Install ffmpeg
         run: sudo apt-get install -y ffmpeg
 
+      - name: Cache Playwright browsers
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-${{ hashFiles('pnpm-lock.yaml') }}
+          restore-keys: playwright-chromium-
+
       - name: Install Playwright Chromium
         run: pnpm --filter @git-glimpse/core exec playwright install chromium --with-deps
 

.github/workflows/demo.yml

@@ -30,22 +30,49 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: '20'
+          cache: 'pnpm'
 
       - uses: pnpm/action-setup@v4
 
       - name: Install dependencies
         run: pnpm install
 
+      - name: Build action check script
+        run: pnpm --filter @git-glimpse/action build
+
+      # Check whether the pipeline should run before installing heavy dependencies.
+      # Subsequent steps are gated on this output to skip ffmpeg/Playwright when
+      # the trigger config (on-demand, smart, etc.) decides to skip the run.
+      - name: Check if glimpse should run
+        id: check
+        run: node packages/action/dist/check.js
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          INPUT_CONFIG-PATH: examples/simple-app/git-glimpse.config.ts
+          INPUT_TRIGGER-MODE: ''
+
       - name: Install FFmpeg
+        if: steps.check.outputs.should-run == 'true'
         run: sudo apt-get install -y ffmpeg
 
+      - name: Cache Playwright browsers
+        if: steps.check.outputs.should-run == 'true'
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-${{ hashFiles('pnpm-lock.yaml') }}
+          restore-keys: playwright-chromium-
+
       - name: Install Playwright Chromium
+        if: steps.check.outputs.should-run == 'true'
         run: pnpm --filter @git-glimpse/core exec playwright install chromium --with-deps
 
       - name: Start example app
+        if: steps.check.outputs.should-run == 'true'
         run: node examples/simple-app/server.js &
 
       - name: Wait for app to be ready
+        if: steps.check.outputs.should-run == 'true'
         run: |
           for i in $(seq 1 15); do
             curl -sf http://localhost:3000 && echo "App ready" && exit 0
@@ -55,6 +82,7 @@ jobs:
           echo "App did not become ready" && exit 1
 
       - uses: ./packages/action
+        if: steps.check.outputs.should-run == 'true'
         with:
           preview-url: 'http://localhost:3000'
           config-path: examples/simple-app/git-glimpse.config.ts