diff --git a/bin/gstack-gbrain-sync.ts b/bin/gstack-gbrain-sync.ts
index 61d9e677f7..b64bbad3ab 100644
--- a/bin/gstack-gbrain-sync.ts
+++ b/bin/gstack-gbrain-sync.ts
@@ -289,11 +289,17 @@ function gbrainSupportsSourcesRename(env?: NodeJS.ProcessEnv): boolean {
  * helper can be exercised without a real gbrain CLI.
  */
 export function sourceLocalPath(sourceId: string, env?: NodeJS.ProcessEnv): string | null {
-  const list = execGbrainJson<Array<{ id: string; local_path?: string }>>(
-    ["sources", "list", "--json"],
-    { baseEnv: env },
-  );
-  if (!list) return null;
+  // gbrain v0.30+ returns {"sources":[...]}; older releases returned a bare
+  // array. Handle both shapes so this works across the compat window. The
+  // sibling helper in lib/gbrain-sources.ts (statusForSourceId) already does
+  // this; the v1.40 hostname-fold migration was the lone holdout and crashed
+  // with `list.find is not a function` on every gbrain v0.30+ install.
+  const raw = execGbrainJson<
+    | Array<{ id: string; local_path?: string }>
+    | { sources?: Array<{ id: string; local_path?: string }> }
+  >(["sources", "list", "--json"], { baseEnv: env });
+  if (!raw) return null;
+  const list = Array.isArray(raw) ? raw : raw.sources || [];
   const found = list.find((s) => s.id === sourceId);
   return found?.local_path ?? null;
 }
diff --git a/test/gstack-gbrain-sync.test.ts b/test/gstack-gbrain-sync.test.ts
index 0f1edec214..d3feed12eb 100644
--- a/test/gstack-gbrain-sync.test.ts
+++ b/test/gstack-gbrain-sync.test.ts
@@ -837,4 +837,40 @@ describe("sourceLocalPath", () => {
     });
     expect(sourceLocalPath("any-id", envWithBindir(bindir))).toBeNull();
   });
+
+  // Regression: gbrain v0.30+ wraps the list as {"sources":[...]} instead of
+  // returning a bare array. The previous implementation crashed with
+  // `list.find is not a function` on every current gbrain install, which
+  // broke `runCodeImport`'s hostname-fold migration on first sync after
+  // upgrading to gstack v1.40 + gbrain v0.30+. Both shapes must work to
+  // keep the compat window intact.
+  it("returns local_path when gbrain wraps the list as {sources: [...]} (v0.30+ shape)", () => {
+    makeShim(bindir, {
+      "sources list --json": {
+        stdout: JSON.stringify({
+          sources: [
+            { id: "other-source", local_path: "/x" },
+            { id: "target-id", local_path: "/repo/wrapped" },
+          ],
+        }),
+      },
+    });
+    expect(sourceLocalPath("target-id", envWithBindir(bindir))).toBe("/repo/wrapped");
+  });
+
+  it("returns null when the wrapped {sources: [...]} shape has no matching id", () => {
+    makeShim(bindir, {
+      "sources list --json": {
+        stdout: JSON.stringify({ sources: [{ id: "other", local_path: "/x" }] }),
+      },
+    });
+    expect(sourceLocalPath("missing-id", envWithBindir(bindir))).toBeNull();
+  });
+
+  it("treats {sources: undefined} the same as an empty list", () => {
+    makeShim(bindir, {
+      "sources list --json": { stdout: JSON.stringify({}) },
+    });
+    expect(sourceLocalPath("any-id", envWithBindir(bindir))).toBeNull();
+  });
 });