diff --git a/.claude/hooks/enrich-context.sh b/.claude/hooks/enrich-context.sh
index 7bc6607c..592fcd4d 100644
--- a/.claude/hooks/enrich-context.sh
+++ b/.claude/hooks/enrich-context.sh
@@ -29,7 +29,9 @@ if [ -z "$REL_PATH" ]; then
 fi
 
 # Guard: codegraph DB must exist
-DB_PATH="${CLAUDE_PROJECT_DIR:-.}/.codegraph/graph.db"
+# Use git worktree root so each worktree reads its own DB (avoids WAL contention)
+WORK_ROOT=$(git rev-parse --show-toplevel 2>/dev/null) || WORK_ROOT="${CLAUDE_PROJECT_DIR:-.}"
+DB_PATH="$WORK_ROOT/.codegraph/graph.db"
 if [ ! -f "$DB_PATH" ]; then
   exit 0
 fi
diff --git a/.claude/hooks/update-graph.sh b/.claude/hooks/update-graph.sh
index 9c78e4d6..d0be9cf1 100644
--- a/.claude/hooks/update-graph.sh
+++ b/.claude/hooks/update-graph.sh
@@ -38,16 +38,18 @@ if echo "$FILE_PATH" | grep -qE '(fixtures|__fixtures__|testdata)/'; then
 fi
 
 # Guard: codegraph DB must exist (project has been built at least once)
-DB_PATH="${CLAUDE_PROJECT_DIR:-.}/.codegraph/graph.db"
+# Use git worktree root so each worktree uses its own DB (avoids WAL contention)
+WORK_ROOT=$(git rev-parse --show-toplevel 2>/dev/null) || WORK_ROOT="${CLAUDE_PROJECT_DIR:-.}"
+DB_PATH="$WORK_ROOT/.codegraph/graph.db"
 if [ ! -f "$DB_PATH" ]; then
   exit 0
 fi
 
 # Run incremental build (skips unchanged files via hash check)
 if command -v codegraph &>/dev/null; then
-  codegraph build "${CLAUDE_PROJECT_DIR:-.}" -d "$DB_PATH" 2>/dev/null || true
+  codegraph build "$WORK_ROOT" -d "$DB_PATH" 2>/dev/null || true
 else
-  node "${CLAUDE_PROJECT_DIR}/src/cli.js" build "${CLAUDE_PROJECT_DIR:-.}" -d "$DB_PATH" 2>/dev/null || true
+  node "${CLAUDE_PROJECT_DIR:-$WORK_ROOT}/src/cli.js" build "$WORK_ROOT" -d "$DB_PATH" 2>/dev/null || true
 fi
 
 exit 0
diff --git a/docs/examples/claude-code-hooks/enrich-context.sh b/docs/examples/claude-code-hooks/enrich-context.sh
index 52d80c3d..9a1ee94b 100644
--- a/docs/examples/claude-code-hooks/enrich-context.sh
+++ b/docs/examples/claude-code-hooks/enrich-context.sh
@@ -29,7 +29,9 @@ if [ -z "$REL_PATH" ]; then
 fi
 
 # Guard: codegraph DB must exist
-DB_PATH="${CLAUDE_PROJECT_DIR:-.}/.codegraph/graph.db"
+# Use git worktree root so each worktree reads its own DB (avoids WAL contention)
+WORK_ROOT=$(git rev-parse --show-toplevel 2>/dev/null) || WORK_ROOT="${CLAUDE_PROJECT_DIR:-.}"
+DB_PATH="$WORK_ROOT/.codegraph/graph.db"
 if [ ! -f "$DB_PATH" ]; then
   exit 0
 fi
diff --git a/docs/examples/claude-code-hooks/update-graph.sh b/docs/examples/claude-code-hooks/update-graph.sh
index 1d9fde02..6b5ee577 100644
--- a/docs/examples/claude-code-hooks/update-graph.sh
+++ b/docs/examples/claude-code-hooks/update-graph.sh
@@ -38,16 +38,18 @@ if echo "$FILE_PATH" | grep -qE '(fixtures|__fixtures__|testdata)/'; then
 fi
 
 # Guard: codegraph DB must exist (project has been built at least once)
-DB_PATH="${CLAUDE_PROJECT_DIR:-.}/.codegraph/graph.db"
+# Use git worktree root so each worktree uses its own DB (avoids WAL contention)
+WORK_ROOT=$(git rev-parse --show-toplevel 2>/dev/null) || WORK_ROOT="${CLAUDE_PROJECT_DIR:-.}"
+DB_PATH="$WORK_ROOT/.codegraph/graph.db"
 if [ ! -f "$DB_PATH" ]; then
   exit 0
 fi
 
 # Run incremental build (skips unchanged files via hash check)
 if command -v codegraph &>/dev/null; then
-  codegraph build "${CLAUDE_PROJECT_DIR:-.}" -d "$DB_PATH" 2>/dev/null || true
+  codegraph build "$WORK_ROOT" -d "$DB_PATH" 2>/dev/null || true
 else
-  npx --yes @optave/codegraph build "${CLAUDE_PROJECT_DIR:-.}" -d "$DB_PATH" 2>/dev/null || true
+  npx --yes @optave/codegraph build "$WORK_ROOT" -d "$DB_PATH" 2>/dev/null || true
 fi
 
 exit 0
diff --git a/src/db/connection.ts b/src/db/connection.ts
index e18b3c8b..333bc6ce 100644
--- a/src/db/connection.ts
+++ b/src/db/connection.ts
@@ -311,6 +311,7 @@ export function openReadonlyOrFail(customPath?: string): BetterSqlite3Database {
   }
   const Database = getDatabase();
   const db = new Database(dbPath, { readonly: true }) as unknown as BetterSqlite3Database;
+  db.pragma('busy_timeout = 5000');
 
   warnOnVersionMismatch(() => {
     const row = db
@@ -378,7 +379,13 @@ export function openRepo(
       // Re-throw user-visible errors (e.g. DB not found) — only silently
       // fall back for native-engine failures (e.g. incompatible native binary).
       if (e instanceof DbError) throw e;
-      debug(`openRepo: native path failed, falling back to better-sqlite3: ${toErrorMessage(e)}`);
+      // Re-throw locking/busy errors — falling back to better-sqlite3 would
+      // hit the same contention (and potentially hang without busy_timeout).
+      const msg = toErrorMessage(e);
+      if (/\b(busy|locked|SQLITE_BUSY|SQLITE_LOCKED)\b/i.test(msg)) {
+        throw new DbError(`Database is busy (another process may be writing): ${msg}`, {});
+      }
+      debug(`openRepo: native path failed, falling back to better-sqlite3: ${msg}`);
     }
   }
 
@@ -412,7 +419,12 @@ export function openReadonlyWithNative(customPath?: string): {
       const native = getNative();
       nativeDb = native.NativeDatabase.openReadonly(dbPath);
     } catch (e) {
-      debug(`openReadonlyWithNative: native path failed: ${toErrorMessage(e)}`);
+      const msg = toErrorMessage(e);
+      if (/\b(busy|locked|SQLITE_BUSY|SQLITE_LOCKED)\b/i.test(msg)) {
+        debug(`openReadonlyWithNative: native path busy, skipping native DB: ${msg}`);
+      } else {
+        debug(`openReadonlyWithNative: native path failed: ${msg}`);
+      }
     }
   }
 
diff --git a/tests/unit/db.test.ts b/tests/unit/db.test.ts
index 055afac9..1b635d5c 100644
--- a/tests/unit/db.test.ts
+++ b/tests/unit/db.test.ts
@@ -380,4 +380,16 @@ describe('openReadonlyOrFail', () => {
     expect(tables).toContain('nodes');
     readDb.close();
   });
+
+  it('sets busy_timeout pragma to 5000 on readonly connections', () => {
+    const dbPath = path.join(tmpDir, 'readonly-busy.db');
+    const db = openDb(dbPath);
+    initSchema(db);
+    closeDb(db);
+
+    const readDb = openReadonlyOrFail(dbPath);
+    const timeout = readDb.pragma('busy_timeout', { simple: true });
+    expect(timeout).toBe(5000);
+    readDb.close();
+  });
 });
diff --git a/tests/unit/openRepo-busy.test.ts b/tests/unit/openRepo-busy.test.ts
new file mode 100644
index 00000000..41c3e730
--- /dev/null
+++ b/tests/unit/openRepo-busy.test.ts
@@ -0,0 +1,54 @@
+/**
+ * Tests that openRepo re-throws SQLITE_BUSY errors from the native engine
+ * instead of silently falling back to better-sqlite3 (which could hang).
+ */
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
+
+// Mock native module to simulate SQLITE_BUSY
+vi.mock('../../src/infrastructure/native.js', () => ({
+  isNativeAvailable: () => true,
+  getNative: () => ({
+    NativeDatabase: {
+      openReadonly: () => {
+        throw new Error('Failed to open DB readonly: SQLITE_BUSY');
+      },
+    },
+  }),
+}));
+
+import { closeDb, initSchema, openDb, openRepo } from '../../src/db/index.js';
+
+let tmpDir: string;
+let dbPath: string;
+
+beforeAll(() => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-busy-'));
+  dbPath = path.join(tmpDir, 'graph.db');
+  const db = openDb(dbPath);
+  initSchema(db);
+  closeDb(db);
+});
+
+afterAll(() => {
+  if (tmpDir) fs.rmSync(tmpDir, { recursive: true, force: true });
+});
+
+describe('openRepo locking error handling', () => {
+  it('re-throws SQLITE_BUSY as DbError instead of falling back', () => {
+    expect(() => openRepo(dbPath)).toThrow(/Database is busy/);
+  });
+
+  it('thrown error is a DbError with code DB_ERROR', () => {
+    try {
+      openRepo(dbPath);
+      expect.unreachable('should have thrown');
+    } catch (err) {
+      expect(err.name).toBe('DbError');
+      expect(err.code).toBe('DB_ERROR');
+      expect(err.message).toContain('SQLITE_BUSY');
+    }
+  });
+});