[Bug] Multi-agent workflows terminate on transient server errors instead of retrying with backoff

Bug Description
Subject: Multi-agent workflows die on transient server-side errors instead of retrying — forcing token-costly manual re-runs

What happens: When a Claude Code workflow agent hits a server-side error — "500 Internal server error", "529 Overloaded", or "Server is temporarily limiting requests (not your usage limit) · Rate limited" — the agent terminates and can take the whole workflow run down with it. The partial work is discarded and the run must be relaunched manually, re-consuming tokens already spent on work that completed.

Observed in a single session (2026-06-23/24):

1. One server-side rate-limit event killed two concurrent workflows at once — one after ~94k agent tokens, the other after ~278k — both returning zero usable output and requiring full re-launch (~372k tokens redone).
2. A review workflow hit "529 Overloaded" and failed. Re-running via resume reused the cached build agents (good — so the partial work is recoverable), but the review re-ran.
3. A main-loop "500 Internal server error" interrupted the session (recovered via --continue).

Suggested fix: Treat transient server-side errors (5xx / overload / server-side rate-limit — i.e. not the user's usage limit) as retryable inside the workflow — auto-retry the failing agent with backoff rather than terminating the run. The resume-with-cache mechanism already proves the completed agents are recoverable; making that retry automatic on transient server failures would eliminate the wasted tokens and the manual relaunches.

Frequency: Several times per day.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.183
• Feedback ID: fe491fd7-66cf-4cfc-95bc-8e972b962544

Errors

[{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011CcLLHygLxG7ZGPje9BEDR\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:12:69182)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:52:7688)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-06-23T14:16:21.038Z"},{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011CcLLTCodbPpeR6R4hhaPW\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:12:69182)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:52:7688)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-06-23T14:18:26.209Z"},{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011CcLLVRTgzvu92tp3EeLPw\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:12:69182)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:52:7688)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-06-23T14:18:56.258Z"}]