fix(server): shed only retryable object-journal reads under load (#19176)

Client polling can exhaust the shared object journal queue and reject log persistence. Bound ordinary object-log and trace reads, keep persistence and internal verification queued, and return retryable 503 responses when reads are busy. Leave feedback exports unsent until every log page is available.

Validation: 72 latest-master affected tests and 10 workflow tests pass locally, with the workflow fixture passing strict TypeScript checks. The preceding broader run passed 280 server tests with two opt-in S3 skips. All applicable checks on d0a937768d are green (56 success, three skipped); exact-head Apex review is 5/5 with no unresolved findings. Background persistence still has no fixed queue bound during a prolonged storage outage.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/native-runtime/native-run-log-export.ts

@@ -309,7 +309,7 @@ export async function nativeRunLogPrefixCursor(input: {
   while (offset < bytes) {
     input.signal?.throwIfAborted();
     const page = await input.store.read(input.handle, {
-      offset, limitBytes: Math.min(256_000, bytes - offset), signal: input.signal,
+      offset, limitBytes: Math.min(256_000, bytes - offset), signal: input.signal, priority: "background",
     });
     const content = Buffer.from(page.content);
     if (!content.length || offset + content.length > bytes) throw unproven();

server/src/services/native-runtime/native-run-log-recovery.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it, vi } from "vitest";
+import type { Db } from "@paperclipai/db";
+import type { RunLogStore } from "../run-log-store.js";
+import { readRecoverableRunLog } from "./native-run-log-recovery.js";
+
+describe("recoverable run log reads", () => {
+  it("lets the client log poll be shed under load and keeps the caller's options", async () => {
+    const read = vi.fn(async () => ({ content: "", nextOffset: 0 }));
+    const store = { read } as unknown as RunLogStore;
+    const handle = { store: "local_file" as const, logRef: "logs/run.ndjson" };
+    const signal = new AbortController().signal;
+    await readRecoverableRunLog({} as Db, store, handle, { offset: 12, limitBytes: 64, signal });
+    expect(read).toHaveBeenCalledWith(handle, {
+      priority: "interactive",
+      offset: 12,
+      limitBytes: 64,
+      signal,
+    });
+  });
+});

server/src/services/native-runtime/native-run-log-recovery.ts

@@ -73,7 +73,7 @@ export async function readRecoverableRunLog(
         );
       },
     );
-  return store.read(handle, options);
+  return store.read(handle, { priority: "interactive", ...options });
 }
 
 export async function recoverSettledNativeRunLog(