When `allowSyntheticToolResults` is false (OpenAI, OpenRouter, and most
third-party providers), the guard never cleared its pending tool call map
when a user message arrived during in-flight tool execution. This left
orphaned tool_use blocks in the transcript with no matching tool_result,
causing the provider API to reject all subsequent requests with 400 errors
and permanently breaking the session.
The fix removes the `allowSyntheticToolResults` gate around the flush
calls. `flushPendingToolResults()` already handles both cases correctly:
it only inserts synthetic results when allowed, and always clears the
pending map. The gate was preventing the map from being cleared at all
for providers that disable synthetic results.
Fixes#32098
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
When an assistant message with toolCalls has stopReason 'aborted' or 'error',
the guard should not add those tool call IDs to the pending map. Creating
synthetic tool results for incomplete/aborted tool calls causes API 400 errors:
'unexpected tool_use_id found in tool_result blocks'
This aligns the WRITE path (session-tool-result-guard.ts) with the READ path
(session-transcript-repair.ts) which already skips aborted messages.
Fixes: orphaned tool_result causing session corruption
Tests added:
- does NOT create synthetic toolResult for aborted assistant messages
- does NOT create synthetic toolResult for errored assistant messages
Synchronous hook that lets plugins inspect and optionally block messages
before they are written to the session JSONL file. Primary use case is
private mode... when enabled, the plugin returns { block: true } and the
message never gets persisted.
The hook runs on the hot path (synchronous, like tool_result_persist).
Handlers execute sequentially in priority order. If any handler returns
{ block: true }, the write is skipped immediately. Handlers can also
return a modified message to write instead of the original.
Changes:
- src/plugins/types.ts: add hook name, event/result types, handler map entry
- src/plugins/hooks.ts: add runBeforeMessageWrite() following tool_result_persist pattern
- src/agents/session-tool-result-guard.ts: invoke hook before every originalAppend() call
- src/agents/session-tool-result-guard-wrapper.ts: wire hook runner to the guard
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* fix: gracefully handle oversized tool results causing context overflow
When a subagent reads a very large file or gets a huge tool result (e.g.,
gh pr diff on a massive PR), it can exceed the model's context window in
a single prompt. Auto-compaction can't help because there's no older
history to compact — just one giant tool result.
This adds two layers of defense:
1. Pre-emptive: Hard cap on tool result size (400K chars ≈ 100K tokens)
applied in the session tool result guard before persistence. This
prevents extremely large tool results from being stored in full,
regardless of model context window size.
2. Recovery: When context overflow is detected and compaction fails,
scan session messages for oversized tool results relative to the
model's actual context window (30% max share). If found, truncate
them in the session via branching (creating a new branch with
truncated content) and retry the prompt.
The truncation preserves the beginning of the content (most useful for
understanding what was read) and appends a notice explaining the
truncation and suggesting offset/limit parameters for targeted reads.
Includes comprehensive tests for:
- Text truncation with newline-boundary awareness
- Context-window-proportional size calculation
- In-memory message truncation
- Oversized detection heuristics
- Guard-level size capping during persistence
* fix: prep fixes for tool result truncation PR (#11579) (thanks @tyler6204)
