Fix /_/health reporting stale degraded status after schema recovers

src/__tests__/handler/schema-guard.test.ts

@@ -308,6 +308,22 @@ describe("GET /_/health", () => {
     expect(body.status).toBe("degraded");
     expect(body.schema.error).toContain("D1 is unavailable right now");
   });
+
+  it("recovers once a fresh live read reports the schema ready, even with a failure remembered from before", async () => {
+    // This isolate's first attempt hits a transient error and remembers it.
+    await worker.fetch(req("/x"), { ...env, DB: brokenDb("D1 is unavailable right now") }, createExecutionContext());
+    // The schema is then genuinely applied for real, the way another isolate
+    // racing the same cold start would: through migrate() directly, without
+    // this isolate's ensureSchema() ever running again to clear its memo.
+    await migrate(env);
+
+    const res = await SELF.fetch(req("/_/health"));
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { status: string; schema: { ready: boolean; error?: string } };
+    expect(body.status).toBe("ok");
+    expect(body.schema.ready).toBe(true);
+    expect(body.schema.error).toBeUndefined();
+  });
 });
 
 describe("/_/setup", () => {

src/api/health.ts

@@ -25,6 +25,11 @@ export async function handleHealth(env: Env): Promise<Response> {
     const status = await schemaStatus(env);
     applied = status.applied.length > 0 ? status.applied[status.applied.length - 1].name : null;
     ready = status.ready;
+    // A live read that finds every migration applied is direct proof the
+    // schema is fine right now, even on an isolate that still remembers an
+    // earlier attempt failing (its own, or one it never repeated because
+    // health is exempt from ensureSchema()).
+    if (ready) error = null;
   } catch (err) {
     error = err instanceof Error ? err.message : String(err);
   }