test(smoke): add smoke_guard.sh for guard and ghost-file invariants

Asserts that query handlers return a guard error for unknown projects
and that no ghost .db file is created in the cache directory.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/smoke_guard.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+# smoke_guard.sh — Smoke test for guard and ghost-file invariants.
+#
+# Verifies two properties:
+#   1. Query handlers return "project not indexed" for unknown projects.
+#   2. No ghost .db file is created for the unknown project name.
+#
+# Usage: bash tests/smoke_guard.sh
+# Exit 0 on success, non-zero on failure.
+
+set -euo pipefail
+
+PROJECT_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BINARY="$PROJECT_ROOT/build/c/codebase-memory-mcp"
+FAKE_PROJECT="nonexistent_smoke_test_xyz"
+CACHE_DIR="${HOME}/.cache/codebase-memory-mcp"
+GHOST_FILE="$CACHE_DIR/${FAKE_PROJECT}.db"
+
+# ── Step 1: Build ─────────────────────────────────────────────────
+echo "[smoke_guard] Building project..."
+make -f "$PROJECT_ROOT/Makefile.cbm" cbm -C "$PROJECT_ROOT" --quiet 2>&1
+if [ ! -x "$BINARY" ]; then
+    echo "[smoke_guard] FAIL: binary not found at $BINARY after build" >&2
+    exit 1
+fi
+echo "[smoke_guard] Build OK: $BINARY"
+
+# ── Step 2: Pre-clean ghost file if somehow present ───────────────
+if [ -f "$GHOST_FILE" ]; then
+    echo "[smoke_guard] WARNING: ghost file already exists before test; removing: $GHOST_FILE"
+    rm -f "$GHOST_FILE"
+fi
+
+# ── Step 3: Invoke query tool with unknown project ────────────────
+echo "[smoke_guard] Invoking search_graph with project='$FAKE_PROJECT'..."
+RESPONSE="$("$BINARY" cli search_graph "{\"project\":\"$FAKE_PROJECT\",\"name_pattern\":\".*\"}" 2>/dev/null)"
+echo "[smoke_guard] Response: $RESPONSE"
+
+# ── Step 4: Assert error message present ─────────────────────────
+# For a truly absent project (no .db file), cbm_store_open_path_query returns
+# NULL, so REQUIRE_STORE fires with "no project loaded" before
+# verify_project_indexed is reached. Both messages confirm the guard is active.
+if ! echo "$RESPONSE" | grep -qE "no project loaded|not indexed"; then
+    echo "[smoke_guard] FAIL: response does not contain guard error ('no project loaded' or 'not indexed')" >&2
+    echo "[smoke_guard] Got: $RESPONSE" >&2
+    exit 1
+fi
+echo "[smoke_guard] PASS: guard error message present"
+
+# ── Step 5: Assert no ghost .db file was created ─────────────────
+if [ -f "$GHOST_FILE" ]; then
+    echo "[smoke_guard] FAIL: ghost file was created at $GHOST_FILE" >&2
+    rm -f "$GHOST_FILE"
+    exit 1
+fi
+echo "[smoke_guard] PASS: no ghost .db file created"
+
+echo "[smoke_guard] All checks passed."
+exit 0