a spawned session says who started it

The other half of making a spawned agent visible. The commander's pane now lists
its children; opening one gave no way back — no link to the conversation that owns
it, and nothing to tell it apart from a chat somebody had started themselves and
forgotten.

`parentCommanderOf` is the row `ingestSpawnedChildren` already writes, read from
the other end. So this needed no table and no write path: a commander's children
were recorded because deleting one has to take them with it, and that record
answers "who is my parent" for free. Nothing had asked.

`GET /chat/sessions/:id` carries `spawnedBy`, and the chat panel renders one line
above the transcript linking back to the commander. Null for almost every session,
which is the normal case rather than a miss — a chat somebody opened has no parent
— so the bar renders nothing at all rather than saying so. Never fatal: a session
must open when this lookup will not.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/databases/officer_db/src/command-hq/index.ts

@@ -15,6 +15,7 @@ export {
   disarmCommandHqWatcher,
   recordCommandHqTurn,
   ingestSpawnedChildren,
+  parentCommanderOf,
   recordSpawnedOutcome,
   getCommandHqCostSummary,
   listCommandHqTurns,

src/databases/officer_db/src/command-hq/queries.ts

@@ -475,3 +475,44 @@ export async function recordSpawnedOutcome(
       and(eq(commandHqSpawned.sessionRowId, sessionRowId), eq(commandHqSpawned.spawnedSessionId, spawnedSessionId)),
     );
 }
+
+export type SpawnParent = {
+  /** The commander's transcript id — what `/command-hq/<id>` opens. */
+  sessionId: string;
+  /** What the owner called it, or null for a commander filed before the column existed. */
+  name: string | null;
+  firstSeenAt: string;
+  finishedAt: string | null;
+};
+
+/**
+ * Which commander spawned this session, if any.
+ *
+ * The same row `ingestSpawnedChildren` writes, read from the other end — so this needed no new table and no
+ * new write path. A commander's children were already recorded because deleting one has to take them with
+ * it; that record answers "who is my parent" for free, and nothing was asking.
+ *
+ * Null for almost every session, and that is the normal case rather than a miss: a chat somebody opened
+ * themselves has no parent, and a session spawned by anything other than a commander has no row here. The
+ * caller must treat absence as "not spawned", never as "lookup failed".
+ */
+export async function parentCommanderOf(spawnedSessionId: string): Promise<SpawnParent | null> {
+  const [row] = await db
+    .select({
+      sessionId: commandHqSessions.sessionId,
+      name: commandHqSessions.name,
+      firstSeenAt: commandHqSpawned.firstSeenAt,
+      finishedAt: commandHqSpawned.finishedAt,
+    })
+    .from(commandHqSpawned)
+    .innerJoin(commandHqSessions, eq(commandHqSessions.id, commandHqSpawned.sessionRowId))
+    .where(eq(commandHqSpawned.spawnedSessionId, spawnedSessionId))
+    .limit(1);
+  if (!row) return null;
+  return {
+    sessionId: row.sessionId,
+    name: row.name,
+    firstSeenAt: row.firstSeenAt.toISOString(),
+    finishedAt: row.finishedAt ? row.finishedAt.toISOString() : null,
+  };
+}