fix(task-store): tolerate Windows EPERM/EACCES rename during atomic save

[leonastar215gh]

fix(task-store): tolerate intermittent Windows EPERM/EACCES rename failures when saving tasks

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Summary

On Windows (especially in corporate environments with antivirus / file indexers / DLP), atomic rename(tmp -> target) can intermittently fail with EPERM/EACCES. When this happens inside the A2A gateway task store, the durable task state cannot be persisted and long-running A2A flows (async task mode, --non-blocking --wait / tasks/get) become unreliable.

This PR makes FileTaskStore.save() more resilient:

• keep atomic rename as the fast/primary path
• when rename fails with EPERM/EACCES, retry a few times with small backoff
• if it still fails, fall back to a best-effort non-atomic overwrite write, and clean up the tmp file

This changes a hard failure into a recoverable path so polling can continue.

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Why this matters

A2A async task mode relies on being able to persist incremental task states. A single failure to write the task JSON can break polling and make agent-to-agent messaging appear flaky.

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Repro (Windows)

1. Run A2A Gateway on Windows.
2. Trigger async tasks at a moderate rate (or concurrently), especially on a machine with active antivirus/indexing.
3. This is easiest to reproduce when running multiple OpenClaw profiles on the same machine/user (shared task store directory), but the underlying file-lock race can also happen in single-gateway setups.
4. Observe intermittent:

EPERM: operation not permitted, rename '<task>.json.<pid>.<ts>.tmp' -> '<task>.json'

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Fix

src/task-store.ts:

• wrap rename(tmp, target) in a try/catch
• only handle EPERM/EACCES
• short backoff retries
• fallback to writeFile(target, payload) + best-effort tmp cleanup

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Deployment / config note (recommended)

When running multiple OpenClaw profiles on the same Windows user, do not share the default task store directory.

Recommend configuring per-profile:

• plugins.entries.a2a-gateway.config.storage.tasksDir

Example:

{
  "plugins": {
    "entries": {
      "a2a-gateway": {
        "config": {
          "storage": {
            "tasksDir": "C:/Users/<user>/.openclaw-<profile>/a2a-tasks"
          }
        }
      }
    }
  }
}

This reduces cross-profile collisions and further improves stability.

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Testing

• npx tsc --noEmit
• npm test

CI already runs on ubuntu; the change is isolated and should be platform-safe.