From ab593cb3e138701aa288191b15edc4beb10e943c Mon Sep 17 00:00:00 2001
From: laofoot <laofoot@gmail.com>
Date: Wed, 17 Jun 2026 14:47:21 +0800
Subject: [PATCH] fix(sessions): detach child sessions before delete to avoid
 FK rollback

deleteSessionRows deleted messages + the session row but never handled
rows referencing it via the self-referential FK parent_session_id ->
sessions.id (set by the agent backend for subagent runs / branches).

better-sqlite3 enables PRAGMA foreign_keys=ON by default, so deleting a
parent that still has a child threw 'FOREIGN KEY constraint failed'.
deleteSession/deleteSessions run inside one transaction, so the violation
rolled back the entire transaction -> 0 rows deleted, with no surfaced
error (the renderer only console.errors it). A select-all delete almost
always contains a parent->child pair, so the whole batch deleted nothing.

Detach children (UPDATE parent_session_id = NULL) before deleting, guarded
by a column-existence check for older schemas. Children are preserved
(not cascade-deleted) so a session the user didn't select is never removed.

Closes #276
---
 src/main/sessions.ts | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/main/sessions.ts b/src/main/sessions.ts
index d75994395..cf69cfad5 100644
--- a/src/main/sessions.ts
+++ b/src/main/sessions.ts
@@ -724,9 +724,39 @@ function normalizeSessionIds(sessionIds: string[]): string[] {
   return normalized;
 }
 
+// sessions has a self-referential FK parent_session_id -> sessions.id (set by
+// the agent for subagent runs / branches). Cached after first lookup.
+let sessionsHasParentColumn: boolean | null = null;
+function hasParentSessionColumn(db: Database.Database): boolean {
+  if (sessionsHasParentColumn !== null) return sessionsHasParentColumn;
+  try {
+    sessionsHasParentColumn =
+      db
+        .prepare(
+          "SELECT 1 FROM pragma_table_info('sessions') WHERE name = 'parent_session_id'",
+        )
+        .get() != null;
+  } catch {
+    sessionsHasParentColumn = false;
+  }
+  return sessionsHasParentColumn;
+}
+
 function deleteSessionRows(db: Database.Database, sessionId: string): number {
   deletePromptImageAttachmentsForSession(db, sessionId);
   deleteSessionContinuationForSession(db, sessionId);
+  // Unlink any child sessions first. better-sqlite3 enables
+  // PRAGMA foreign_keys=ON by default, so deleting a parent while a child
+  // still references it via parent_session_id throws "FOREIGN KEY constraint
+  // failed", which rolls back the whole delete transaction -> 0 rows deleted
+  // with no surfaced error (and a select-all batch deletes nothing, since one
+  // violation aborts the entire transaction). Detach children rather than
+  // cascade-delete so a session the user didn't select is never removed.
+  if (hasParentSessionColumn(db)) {
+    db.prepare(
+      "UPDATE sessions SET parent_session_id = NULL WHERE parent_session_id = ?",
+    ).run(sessionId);
+  }
   db.prepare("DELETE FROM messages WHERE session_id = ?").run(sessionId);
   const result = db.prepare("DELETE FROM sessions WHERE id = ?").run(sessionId);
   return result.changes;