Fixed incorrect auto-compaction on 429 errorsPublic

Agent

Model

Claude Opus 4.5 (latest)

Started

Jan 28, 11:35 PM

Messages71

Downloads0

Summary

Closed, Completed

Understand
Analyzed GitHub issue and related comments.
Understand
Understand
Traced code path for error handling and context overflow.
Understand
Edit
Modified overflow detection to exclude 429 errors.
Edit
Edit
Updated retry logic and changelog.
Edit
Verify
Committed, pushed, and commented to close issue.
Verify

Analyze GitHub issue(s): https://github.com/badlogic/pi-mono/issues/1038 figure out why we auto-compact on 429

For each issue:

Read the issue in full, including all comments and linked issues/PRs.
For bugs:
- Ignore any root cause analysis in the issue (likely wrong)
- Read all related code files in full (no truncation)
- Trace the code path and identify the actual root cause
- Propose a fix
For feature requests:
- Read all related code files in full (no truncation)
- Propose the most concise implementation approach
- List affected files and changes needed

Do NOT implement unless explicitly asked. Analyze and propose only.

Now let me trace the code path. I'll look at how errors are handled and where context overflow detection occurs.

Let me look at the isContextOverflow function to understand how context overflow is detected:

Let me check the retry error handling logic:

Let me read the full retry error detection logic:

Analysis Complete

Issue Summary

429 HTTP status code (rate limiting) incorrectly triggers auto-compaction instead of retry with backoff.

Root Cause

File: packages/ai/src/utils/overflow.ts, lines 91-94

typescript

// Cerebras and Mistral return 400/413/429 with no body - check for status code pattern// 429 can indicate token-based rate limiting which correlates with context overflowif (/^4(00|13|29)\s*(status code)?\s*\(no body\)/i.test(message.errorMessage)) {    return true;}

The code treats 429 status code (no body) as context overflow. The comment's reasoning is flawed:

Token-based rate limiting (TPM): Limits tokens per minute/hour across all requests (throughput limit)
Context overflow: A single request's input exceeds the model's context window (size limit)

These are completely different concepts. 429 = "Too Many Requests" = rate limiting, NOT context overflow.

The Bug Flow

User sends requests → provider returns 429 status code (no body) (rate limited)
isContextOverflow() returns true (matches regex)
_isRetryableError() in agent-session.ts:1879 returns false:
typescript
```
if (isContextOverflow(message, contextWindow)) return false;
```
_checkCompaction() triggers auto-compaction because isContextOverflow() is true
Compaction attempt also gets 429 (still rate limited)
User sees nonsensical "Compacted from 35 tokens"

Proposed Fix

Change in packages/ai/src/utils/overflow.ts:

Keep:

400 (Bad Request) - could be context overflow from some providers
413 (Payload Too Large) - definitely could be context overflow

Remove:

429 (Too Many Requests) - rate limiting, should be retried

The retry logic already handles 429 correctly. In agent-session.ts:1886-1888:

Once isContextOverflow() stops returning true for 429, _isRetryableError() will correctly return true, and 429 errors will be retried with exponential backoff as expected.

Files to Change

packages/ai/src/utils/overflow.ts - Remove 429 from overflow regex
packages/ai/CHANGELOG.md - Document the fix

do it

Done. Changes made:

packages/ai/src/utils/overflow.ts:

Changed regex from /^4(00|13|29) to /^4(00|13) to exclude 429 from context overflow detection
Updated comments to reflect that 429 is rate limiting, not context overflow

packages/ai/CHANGELOG.md:

Added fix entry under [Unreleased]

The fix ensures 429 errors are now correctly handled by the retry logic (exponential backoff) in agent-session.ts instead of triggering auto-compaction. The existing retry regex already matches 429:

commit and push, leave a comment explaining the fix. close issue in commit message

Done. Committed, pushed, and commented on the issue. The issue will be auto-closed by GitHub due to fixes #1038 in the commit message.