seed-build-cache.yml

name: Build Size Cache

# Manual workflow to seed the build-sizes cache for a branch,
# or to verify that a cache entry already exists.
#
# Usage:
#   - "seed":   Build the selected branch and save its VSIX + webview sizes to the cache.
#   - "verify": Check whether a cache entry exists for the selected branch (no build needed).

on:
    workflow_dispatch:
        inputs:
            mode:
                description: 'Action to perform'
                required: true
                type: choice
                options:
                    - seed
                    - verify
                default: seed

jobs:
    seed:
        name: Seed build size cache
        runs-on: ubuntu-latest
        if: inputs.mode == 'seed'
        permissions:
            contents: read
            actions: write
        steps:
            - name: ✅ Checkout Repository
              uses: actions/checkout@v6

            - name: 🛠 Setup Node.js Environment (with cache)
              uses: actions/setup-node@v5
              with:
                  node-version-file: .nvmrc
                  cache: npm
                  cache-dependency-path: '**/package-lock.json'

            - name: 📦 Install Dependencies
              run: npm ci --prefer-offline --no-audit --no-fund --progress=false

            - name: 🏗 Build Project
              run: npm run build

            - name: 📦 Package Distributables
              run: npm run package

            - name: 📐 Collect build sizes
              id: sizes
              run: |
                  VSIX_FILE=$(find . -maxdepth 1 -name '*.vsix' | head -1)
                  VSIX_SIZE=$(stat --format=%s "$VSIX_FILE")
                  WEBVIEW_SIZE=$(stat --format=%s dist/views.js 2>/dev/null || echo 0)
                  CACHE_KEY="build-sizes-${{ github.ref_name }}-${{ github.sha }}"
                  echo "{\"vsixSize\": $VSIX_SIZE, \"webviewSize\": $WEBVIEW_SIZE}" > build-sizes.json
                  echo "### 📐 Build Sizes for \`${{ github.ref_name }}\`" >> $GITHUB_STEP_SUMMARY
                  echo "" >> $GITHUB_STEP_SUMMARY
                  echo "| Metric | Size |" >> $GITHUB_STEP_SUMMARY
                  echo "|--------|------|" >> $GITHUB_STEP_SUMMARY
                  echo "| VSIX (\`$(basename "$VSIX_FILE")\`) | $(numfmt --to=iec --suffix=B $VSIX_SIZE) |" >> $GITHUB_STEP_SUMMARY
                  echo "| Webview bundle (\`views.js\`) | $(numfmt --to=iec --suffix=B $WEBVIEW_SIZE) |" >> $GITHUB_STEP_SUMMARY
                  echo "" >> $GITHUB_STEP_SUMMARY
                  echo "Cache key: \`$CACHE_KEY\`" >> $GITHUB_STEP_SUMMARY

            - name: 💾 Save to cache
              uses: actions/cache/save@v5
              with:
                  path: build-sizes.json
                  key: build-sizes-${{ github.ref_name }}-${{ github.sha }}

            - name: ✅ Done
              run: echo "Cache seeded for ${{ github.ref_name }} @ ${{ github.sha }}"

    verify:
        name: Verify build size cache
        runs-on: ubuntu-latest
        if: inputs.mode == 'verify'
        permissions:
            actions: read
        steps:
            - name: 📥 Attempt exact cache restore
              id: exact
              uses: actions/cache/restore@v5
              with:
                  path: build-sizes.json
                  key: build-sizes-${{ github.ref_name }}-${{ github.sha }}
                  lookup-only: true

            - name: 📥 Attempt prefix cache restore
              id: prefix
              uses: actions/cache/restore@v5
              with:
                  path: build-sizes-prefix.json
                  key: build-sizes-${{ github.ref_name }}-${{ github.sha }}-impossible
                  restore-keys: |
                      build-sizes-${{ github.ref_name }}-
                  lookup-only: true

            - name: 📋 Report results
              uses: actions/github-script@v8
              with:
                  script: |
                      const branch  = '${{ github.ref_name }}';
                      const sha     = '${{ github.sha }}';
                      const exactHit   = '${{ steps.exact.outputs.cache-matched-key }}';
                      const prefixHit  = '${{ steps.prefix.outputs.cache-matched-key }}';

                      const lines = [
                        `### 🔍 Cache Verification for \`${branch}\``,
                        '',
                        `| Check | Result |`,
                        `|-------|--------|`,
                        `| Exact match (\`build-sizes-${branch}-${sha.slice(0,8)}…\`) | ${exactHit ? '✅ Hit: `' + exactHit + '`' : '❌ Miss'} |`,
                        `| Prefix match (\`build-sizes-${branch}-*\`) | ${prefixHit ? '✅ Hit: `' + prefixHit + '`' : '❌ Miss'} |`,
                      ];

                      if (!exactHit && !prefixHit) {
                        lines.push('', '> ⚠️ No cache exists for this branch. Run this workflow again with **seed** mode.');
                      } else if (!exactHit && prefixHit) {
                        lines.push('', `> ℹ️ No exact SHA match, but a previous cache entry exists. PRs will use this as the baseline.`);
                      } else {
                        lines.push('', '> ✅ Cache is up to date for the current HEAD.');
                      }

                      await core.summary.addRaw(lines.join('\n')).write();