Codex review on PR #4351: synthesizing toolCall content blocks for
Cursor's exec-channel native tools made the shared agent loop treat the
finalized assistant message as a fresh runnable tool turn. Because
executeToolCalls filters message.content for any toolCall block on
stop/toolUse, bash/write/delete/etc. ran a second time after Cursor
already executed them server-side via the bridge, duplicating side
effects and appending conflicting toolResults.
- packages/ai/src/utils/block-symbols.ts: add `kCursorExecResolved`
symbol and `CursorExecResolvedCarrier` carrier type. Symbol-keyed so
the marker never leaks into JSONL; rebuild pairs blocks with toolResult
messages by id.
- packages/ai/src/providers/cursor.ts: stamp the marker onto every
block `synthesizeCursorExecToolCall` emits and extend `ToolCallState`.
- packages/agent/src/agent-loop.ts: filter marked blocks out of the
runnable-toolCall extraction in both the main runnable path and the
error/aborted placeholder path, plus defense-in-depth inside
`executeToolCalls`. Marked blocks stay in `assistantMessage.content`
for persistence + rebuild rendering; they just never re-execute.
- packages/agent/test/agent-loop.test.ts: two regression tests — one
proves a marked block yields zero `tool.execute` calls and no
`tool_execution_*` events from the loop, the other verifies mixed
batches still run the unmarked blocks unchanged.
Fixes#4348
roboomp
eb64e7e5d1