Bug Description

JsonFileReadError: File changed during read occurs when paired.json is rewritten while another component is reading it. This is a transient race condition that should be handled gracefully rather than causing gateway failures.

Steps to Reproduce

1. Have multiple gateway clients active (Discord, Control UI, CLI)
2. Trigger a paired.json rewrite (e.g., open openclaw logs --follow)
3. Another component reads paired.json during the temp-file + rename operation
4. Observe error: JsonFileReadError: Failed to read JSON file: /home/simon/.openclaw/devices/paired.json
5. Followed by: gateway closed (1000)

Expected Behavior

JSON file reads should be resilient to concurrent rewrites:

• Retry on File changed during read (max 3 attempts, 50ms backoff)
• Distinguish between "file changed" (retry) and "file corrupted" (fail)
• Do not surface transient read races as gateway failures

Actual Behavior

• Single read attempt fails immediately
• Error propagates as gateway failure
• Triggers websocket reconnect
• Reconnect may trigger another paired.json rewrite → amplification loop

Environment

• OpenClaw version: 2026.5.12
• File write pattern: temp-file + fsync + rename (atomic)
• Read pattern: single attempt, no retry

Related Issues

• paired_devices.createdAt / lastSeenAt are null — cannot identify stale paired clients #81169 — paired.json stale entries and rewrite frequency
• openclaw logs --follow registers as paired device, rewrites paired.json #83656 — openclaw logs --follow registers as paired device
• [Bug]: Gateway data loss: Silent read error on paired.json leads to overwrite of all pairings #71873 — Silent read error on paired.json

Recommendation

Implement bounded retry logic for JSON file reads:

// Pseudocode
async function readJsonFile(path, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fs.readJson(path);
    } catch (err) {
      if (err.message.includes('File changed during read') && i < maxRetries - 1) {
        await sleep(50 * Math.pow(2, i)); // exponential backoff
        continue;
      }
      throw err;
    }
  }
}

This is a standard pattern for atomic file operations and should be applied to all JSON config reads, not just paired.json.