port: sync from Mike/pygienium@595ce48f

src/modes/check-runner.ts

@@ -142,7 +142,12 @@ export async function runCheck(
 ): Promise<CheckRunOutcome> {
 	const startMs = Date.now();
 	const outcome = await runCheckImpl(opts);
-	postCheckCompletion(opts, outcome, Date.now() - startMs);
+	try {
+		postCheckCompletion(opts, outcome, Date.now() - startMs);
+	} catch {
+		// Completion posting is best-effort chat UI: a renderer or send
+		// failure must never reject the run after its state was persisted.
+	}
 	return outcome;
 }
 
@@ -383,7 +388,16 @@ async function runCheckImplInner(
 		error = err instanceof Error ? err.message : String(err);
 		markCheckStatus(state, check.name, "failed", error);
 		markRunStatus(state, reconcileRunStatus(state));
-		await saveRunState(state);
+		try {
+			await saveRunState(state);
+		} catch (saveErr) {
+			// A failing state save inside the error path must not mask the
+			// original error or escape as an unhandled rejection (which would
+			// kill the run with nothing persisted or reported).
+			error += `; (also failed to persist run-state: ${
+				saveErr instanceof Error ? saveErr.message : String(saveErr)
+			})`;
+		}
 		return { status: "failed", error, findings, changes, state };
 	} finally {
 		strip.done();