diff --git a/src/db.ts b/src/db.ts
index 7fba354..5aaf0b1 100644
--- a/src/db.ts
+++ b/src/db.ts
@@ -561,6 +561,10 @@ export function setSession(groupFolder: string, sessionId: string): void {
   ).run(groupFolder, sessionId);
 }
 
+export function deleteSession(groupFolder: string): void {
+  db.prepare('DELETE FROM sessions WHERE group_folder = ?').run(groupFolder);
+}
+
 export function getAllSessions(): Record<string, string> {
   const rows = db
     .prepare('SELECT group_folder, session_id FROM sessions')
diff --git a/src/index.ts b/src/index.ts
index eaf9432..e186c40 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -33,6 +33,7 @@ import {
   getAllChats,
   getAllRegisteredGroups,
   getAllSessions,
+  deleteSession,
   getAllTasks,
   getLastBotMessageTimestamp,
   getMessagesSince,
@@ -402,6 +403,24 @@ async function runAgent(
     }
 
     if (output.status === 'error') {
+      // Detect stale/corrupt session — clear it so the next retry starts fresh.
+      // The session .jsonl can go missing after a crash mid-write, manual
+      // deletion, or disk-full. The existing backoff in group-queue.ts
+      // handles the retry; we just need to remove the broken session ID.
+      const isStaleSession =
+        sessionId &&
+        output.error &&
+        /no conversation found|ENOENT.*\.jsonl|session.*not found/i.test(output.error);
+
+      if (isStaleSession) {
+        logger.warn(
+          { group: group.name, staleSessionId: sessionId, error: output.error },
+          'Stale session detected — clearing for next retry',
+        );
+        delete sessions[group.folder];
+        deleteSession(group.folder);
+      }
+
       logger.error(
         { group: group.name, error: output.error },
         'Container agent error',