test(core): the resumed unwind halt is a stated halt, not a compensate() over no rows

Claude-Session: https://claude.ai/code/session_01DDZNkDVwPQnevTFcYE47H3
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

packages/core/src/utils/migration-journal.test.ts

@@ -599,7 +599,11 @@ describe('a resume compares what the run started over, not what load() returns n
     expect(await chunkEvents(restarted, runId, 'compensated')).toEqual([1]);
     const failure = (await readRunJournal(asEngine(restarted), runId)).at(-1)!;
     expect(failure).toMatchObject({ kind: 'run_failed', chunk_index: 0 });
-    expect(JSON.parse(failure.detail!)).toMatchObject({ phase: 'compensate', step: 'shrinking' });
+    const detail = JSON.parse(failure.detail!);
+    expect(detail).toMatchObject({ phase: 'compensate', step: 'shrinking' });
+    // A halt that says why — not a compensate() that was handed no rows and threw.
+    expect(detail).toHaveProperty('reason');
+    expect(detail).not.toHaveProperty('error');
   });
 });
 

packages/core/src/utils/migration-journal.ts

@@ -610,7 +610,7 @@ function planResumedRun(
  * step's preflight fails; the plan declares `onCrash: 'compensate'` but some
  * step cannot compensate; or a resume's plan disagrees with what its run
  * started over — its hash, or rows that bind to that chunk plan under neither
- * reading `planResumedRun` accepts.
+ * reading {@link MigrationPlanStep.load} documents.
  */
 export async function runMigrationJournal(
   engine: IObjectQLEngine,