diff --git a/container/agent-runner/src/db/connection.ts b/container/agent-runner/src/db/connection.ts
index 3ca44a8..ac563fa 100644
--- a/container/agent-runner/src/db/connection.ts
+++ b/container/agent-runner/src/db/connection.ts
@@ -27,6 +27,13 @@ const DEFAULT_HEARTBEAT_PATH = '/workspace/.heartbeat';
 let _inbound: Database | null = null;
 let _outbound: Database | null = null;
 let _heartbeatPath: string = DEFAULT_HEARTBEAT_PATH;
+// True when initTestSessionDb() set _inbound to an in-memory DB. Used by
+// openInboundDb() so tests don't try to open the missing /workspace path.
+let _inboundIsTest = false;
+// Saved real close() for the in-memory inbound singleton. We no-op the
+// public .close() during tests so caller try/finally doesn't tear down
+// the shared DB; closeSessionDb() invokes this to do the real teardown.
+let _inboundOriginalClose: (() => void) | null = null;
 
 /**
  * Avoid all cached db reads; open inbound.db read-only with mmap and page cache disabled. 
@@ -42,6 +49,12 @@ let _heartbeatPath: string = DEFAULT_HEARTBEAT_PATH;
  * Cost is microseconds per query, so safe for universal use.
  */
 export function openInboundDb(): Database {
+  // In test mode the inbound DB is an in-memory singleton — there is no
+  // file at DEFAULT_INBOUND_PATH. Return the singleton directly; its
+  // .close() was no-op'd in initTestSessionDb so caller try/finally
+  // cleanup doesn't tear down the shared DB.
+  if (_inboundIsTest && _inbound) return _inbound;
+
   const db = new Database(DEFAULT_INBOUND_PATH, { readonly: true });
   db.exec('PRAGMA busy_timeout = 5000');
   db.exec('PRAGMA mmap_size = 0');
@@ -171,6 +184,12 @@ export function clearStaleProcessingAcks(): void {
 /** For tests — creates in-memory DBs with the session schemas. */
 export function initTestSessionDb(): { inbound: Database; outbound: Database } {
   _inbound = new Database(':memory:');
+  _inboundIsTest = true;
+  // No-op .close() so callers using openInboundDb()'s try/finally pattern
+  // don't tear down our shared singleton. closeSessionDb() does the real
+  // teardown via the saved original.
+  _inboundOriginalClose = _inbound.close.bind(_inbound);
+  _inbound.close = () => {};
   _inbound.exec('PRAGMA foreign_keys = ON');
   _inbound.exec(`
     CREATE TABLE messages_in (
@@ -244,8 +263,14 @@ export function initTestSessionDb(): { inbound: Database; outbound: Database } {
 }
 
 export function closeSessionDb(): void {
-  _inbound?.close();
+  if (_inboundOriginalClose) {
+    _inboundOriginalClose();
+    _inboundOriginalClose = null;
+  } else {
+    _inbound?.close();
+  }
   _inbound = null;
+  _inboundIsTest = false;
   _outbound?.close();
   _outbound = null;
 }