Versions

• gstack: 1.40.0.0
• gbrain CLI: gbrain0.35.7.0
• Affected file: bin/gstack-gbrain-sync.ts

Symptom
Running /sync-gbrain (or bun bin/gstack-gbrain-sync.ts --full) when the migration planner inspects a legacy source:

[gbrain-sync] mode=full engine=supabase
gstack-gbrain-sync fatal: list.find is not a function. (In 'list.find((s) => s.id === sourceId)', 'list.find' is undefined)

Exit code 1, orchestrator aborts before any stage runs.

Root cause
sourceLocalPath() (lines 291-299) types the gbrain sources list --json response as a bare array:

const list = execGbrainJson<Array<{ id: string; local_path?: string }>>(
  ["sources", "list", "--json"],
  { baseEnv: env },
);
if (!list) return null;
const found = list.find((s) => s.id === sourceId);

But the CLI actually returns the array wrapped in a sources key:

{
  "sources": [
    { "id": "default", "page_count": 114, ... },
    { "id": "gstack-artifacts-kennedy", "page_count": 0, ... }
  ]
}

So list is the wrapper object, list.find is undefined, and the orchestrator crashes.

The two sibling helpers in lib/gbrain-sources.ts (probeSource at line 51 and sourcePageCount at line 162) already unwrap .sources correctly — only sourceLocalPath was missed.

Fix (three-line patch)

```diff
export function sourceLocalPath(sourceId: string, env?: NodeJS.ProcessEnv): string | null {

• const list = execGbrainJson<Array<{ id: string; local_path?: string }>>(

• const response = execGbrainJson<{ sources?: Array<{ id: string; local_path?: string }> }>(
  ["sources", "list", "--json"],
  { baseEnv: env },
  );

• if (!list) return null;

• if (!response) return null;
• const list = response.sources ?? [];
  const found = list.find((s) => s.id === sourceId);
  return found?.local_path ?? null;
  }
  ```

Trigger conditions
sourceLocalPath is called from planHostnameFoldMigration whenever the hostname-fold migration runs (legacy path-only-hash source id differs from the new hostname-fold id). Anyone upgrading from a pre-#1468 install hits it on their next /sync-gbrain run.

Suggested test
Add a fixture for execGbrainJson returning {sources: [{id:"x", local_path:"/p"}]} and assert sourceLocalPath("x") returns "/p" — current code returns null even before the throw on real input.