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+name: runner-probe
+
+# Probe-only workflow — answers all runner unknowns before real CI is designed.
+# Runs ONLY on the feature branch; never on main.
+# All steps that may fail on this runner use continue-on-error: true or || true
+# so the probe REPORTS findings instead of red-failing on an expected unknown.
+# Do NOT reference any secret in this workflow (T-08-01).
+#
+# Checks performed: P-01 through P-11 + P-13
+# P-12 (docker login) is deferred to Plan 04 (publish) — DO NOT add it here.
+
+on:
+  push:
+    branches:
+      - gsd/phase-08-gitea-ci
+
+jobs:
+  probe:
+    name: runner-probe
+    runs-on: self-hosted
+
+    # P-05: Service container — probe whether it spawns and on which hostname.
+    # Uses healthcheck.sh --connect --innodb_initialized.
+    # Note: healthcheck.sh is used because the binary from older clients was
+    # removed from mariadb:11 (Pitfall 11).
+    services:
+      mariadb:
+        image: mariadb:11
+        env:
+          MARIADB_ROOT_PASSWORD: root
+          MARIADB_DATABASE: familysync
+          MARIADB_USER: familysync
+          MARIADB_PASSWORD: testpass
+        options: >-
+          --health-cmd="healthcheck.sh --connect --innodb_initialized"
+          --health-interval=10s
+          --health-timeout=5s
+          --health-retries=10
+          --health-start-period=30s
+
+    steps:
+      # ─── P-07: actions/checkout ──────────────────────────────────────────────
+      # Must be first real step. Reaching subsequent steps proves it resolves.
+      - name: P-07 checkout (actions/checkout@v4)
+        uses: actions/checkout@v4
+
+      # ─── P-08: actions/setup-node ────────────────────────────────────────────
+      - name: P-08 setup-node (actions/setup-node@v4 — pin Node 22)
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      # ─── P-01: Node.js version ───────────────────────────────────────────────
+      - name: P-01 Node.js version
+        run: |
+          echo "=== P-01: Node.js version ==="
+          node --version
+          echo "Expected: v22.x"
+
+      # ─── P-02: pnpm availability ─────────────────────────────────────────────
+      - name: P-02 pnpm availability
+        run: |
+          echo "=== P-02: pnpm availability ==="
+          pnpm --version 2>/dev/null || (
+            echo "pnpm not found — attempting corepack activation"
+            corepack enable pnpm
+            pnpm --version
+          )
+          echo "Expected: pnpm 11.x (from packageManager field in package.json)"
+
+      # ─── P-03: Runner mode — THE critical fork ───────────────────────────────
+      # Docker-executor mode:  job runs inside a Docker container
+      #   → services: works; DB_HOST=mariadb
+      # Host-executor mode:    job runs directly on the Unraid host
+      #   → services: not supported; must use docker run -d fallback
+      - name: P-03 runner mode detection (Docker vs host — critical fork)
+        run: |
+          echo "=== P-03: Runner mode (critical fork) ==="
+          echo "--- /proc/1/cgroup (first 5 lines) ---"
+          cat /proc/1/cgroup 2>/dev/null | head -5 || echo "(not readable)"
+          echo "--- hostname ---"
+          hostname
+          echo "--- /.dockerenv presence ---"
+          ls -la /.dockerenv 2>&1
+          echo "--- Conclusion ---"
+          if [ -f /.dockerenv ]; then
+            echo "RUNNER MODE: Docker-executor (job is running inside a Docker container)"
+            echo "  → services: will work; MariaDB hostname = service label name (mariadb)"
+            echo "  → DB_HOST=mariadb in downstream jobs"
+          else
+            echo "RUNNER MODE: host-executor (job is running directly on the host)"
+            echo "  → services: NOT supported (nektos/act#2711)"
+            echo "  → Downstream jobs must use: docker run -d mariadb:11 + explicit readiness loop"
+            echo "  → DB_HOST=127.0.0.1 with -p 3306:3306 in docker run"
+          fi
+
+      # ─── P-04: Docker socket access ──────────────────────────────────────────
+      - name: P-04 Docker socket access
+        continue-on-error: true
+        run: |
+          echo "=== P-04: Docker socket access ==="
+          docker info 2>&1 | head -20
+          echo "--- docker ps (first few lines) ---"
+          docker ps 2>&1 | head
+
+      # ─── P-05: Service container spawn check ─────────────────────────────────
+      - name: P-05 service container spawn (mariadb:11 visible in docker ps?)
+        continue-on-error: true
+        run: |
+          echo "=== P-05: Service container spawn ==="
+          docker ps 2>&1 | grep -i maria \
+            && echo "RESULT: MariaDB service container IS visible in docker ps (Docker-executor mode confirmed)" \
+            || echo "RESULT: no mariadb container visible in docker ps (likely host-executor mode — services: not supported)"
+
+      # ─── P-06: MariaDB reachability — try BOTH hostnames ─────────────────────
+      # Does NOT fail the job: records which hostname resolves.
+      - name: P-06 MariaDB reachability (hostname=mariadb — Docker mode)
+        continue-on-error: true
+        run: |
+          echo "=== P-06a: MariaDB via hostname 'mariadb' (Docker-executor mode) ==="
+          mysql -h mariadb -P 3306 -u familysync -ptestpass -e "SELECT 1" 2>&1 | head \
+            && echo "P-06a RESULT: mariadb hostname RESOLVES — Docker mode" \
+            || echo "P-06a RESULT: mariadb hostname DOES NOT resolve (expected if host-executor mode)"
+
+      - name: P-06 MariaDB reachability (hostname=127.0.0.1 — host mode)
+        continue-on-error: true
+        run: |
+          echo "=== P-06b: MariaDB via 127.0.0.1 (host-executor mode fallback) ==="
+          mysql -h 127.0.0.1 -P 3306 -u familysync -ptestpass -e "SELECT 1" 2>&1 | head \
+            && echo "P-06b RESULT: 127.0.0.1 RESOLVES — host mode" \
+            || echo "P-06b RESULT: 127.0.0.1 does not resolve (expected if Docker-executor mode uses 'mariadb' hostname)"
+
+      # ─── P-09: actions/cache ─────────────────────────────────────────────────
+      # Known issue: cache server runs in runner container; job container on different
+      # network may cause socket hang-up. continue-on-error so probe reports finding.
+      - name: P-09 cache action (actions/cache@v4 — may time out in Docker mode)
+        uses: actions/cache@v4
+        continue-on-error: true
+        with:
+          path: /tmp/probe-cache-test
+          key: runner-probe-cache-test-${{ github.sha }}
+
+      - name: P-09 cache result
+        run: |
+          echo "=== P-09: Cache action result ==="
+          echo "If the previous 'cache' step completed without hanging, cache IS usable."
+          echo "If it timed out or errored, fall back to no-cache in downstream jobs."
+
+      # ─── P-10: Playwright WebKit system deps ────────────────────────────────
+      # Confirms WebKit system deps install without sudo/apt failure (Assumption A10).
+      # Runs from apps/pwa where @playwright/test is installed.
+      - name: P-10 Playwright WebKit + Chromium system deps
+        continue-on-error: true
+        working-directory: apps/pwa
+        run: |
+          echo "=== P-10: Playwright browser system deps (webkit + chromium) ==="
+          npx playwright install --with-deps webkit chromium 2>&1 | tail -30
+          echo "--- Exit code: $? ---"
+          echo "If the above shows installed without 'sudo' or 'apt' errors, WebKit deps are OK."
+
+      # ─── P-11: gitea-upload-artifact fork ───────────────────────────────────
+      # The official upload-artifact action is broken on Gitea (detected as GHES, aborts).
+      # Use ChristopherHX/gitea-upload-artifact@v4 — the confirmed Gitea fix (RESEARCH T-08-SC).
+      - name: P-11 write dummy artifact for upload test
+        run: |
+          echo "=== P-11: Upload artifact test ==="
+          mkdir -p /tmp/probe-artifact
+          echo "runner-probe artifact: sha=${GITHUB_SHA}" > /tmp/probe-artifact/probe.txt
+          cat /tmp/probe-artifact/probe.txt
+
+      - name: P-11 artifact upload (ChristopherHX/gitea-upload-artifact@v4)
+        uses: https://github.com/ChristopherHX/gitea-upload-artifact@v4
+        continue-on-error: true
+        with:
+          name: runner-probe-artifact
+          path: /tmp/probe-artifact/
+          retention-days: 3
+
+      # ─── P-13: GITHUB_SHA short SHA expression ───────────────────────────────
+      - name: P-13 short SHA expression (D-04 tag validation)
+        run: |
+          echo "=== P-13: GITHUB_SHA short SHA ==="
+          echo "GITHUB_SHA full  = ${GITHUB_SHA}"
+          echo "short sha = ${GITHUB_SHA:0:7}"
+          echo "Expected: a 7-character hex string — confirms D-04 tag expression works"
+          if [ "${#GITHUB_SHA}" -ge 7 ]; then
+            echo "P-13 RESULT: OK — GITHUB_SHA is available and bash substring works"
+          else
+            echo "P-13 RESULT: WARN — GITHUB_SHA is shorter than expected or empty"
+          fi
+
+      # ─── SUMMARY: one-line verdict per fork ──────────────────────────────────
+      # Plans 02–04 consume these answers to pick the correct implementation path.
+      - name: SUMMARY — fork verdicts (record answers for SUMMARY.md)
+        run: |
+          echo "========================================================"
+          echo "  RUNNER PROBE SUMMARY — FORK ANSWERS"
+          echo "========================================================"
+          echo ""
+          echo "P-03 Runner mode:"
+          if [ -f /.dockerenv ]; then
+            echo "  DOCKER-EXECUTOR — job runs in a container"
+            echo "  → services: works; DB_HOST=mariadb"
+          else
+            echo "  HOST-EXECUTOR — job runs directly on host"
+            echo "  → services: NOT supported; use docker run -d + DB_HOST=127.0.0.1"
+          fi
+          echo ""
+          echo "P-05/P-06 MariaDB service container:"
+          MARIA_CONTAINER=$(docker ps 2>/dev/null | grep -i maria | head -1 || true)
+          if [ -n "$MARIA_CONTAINER" ]; then
+            echo "  Service container IS visible — hostname 'mariadb' should resolve"
+          else
+            echo "  Service container NOT visible — use docker run -d fallback"
+          fi
+          echo ""
+          echo "P-09 Cache: see 'cache' step result above (continue-on-error — pass = usable)"
+          echo "P-10 WebKit deps: see 'playwright install' step above (continue-on-error)"
+          echo "P-11 Upload artifact: see 'gitea-upload-artifact' step above (continue-on-error)"
+          echo ""
+          echo "P-13 Short SHA: ${GITHUB_SHA:0:7}"
+          echo ""
+          echo "  SECURITY CHECK: this probe references NO secrets (T-08-01 compliant)"
+          echo "  P-12 (docker login/push) is deferred to Plan 04 — NOT in this probe."
+          echo "========================================================"