fix: prevent race condition from deleting wrong API messages

[hannesrudolph]

Summary

Fixes a race condition bug where deleting a user message from chat history incorrectly removed assistant API messages that logically preceded the deleted message.

Problem

When deleting a user_feedback clineMessage, the system was using that message's timestamp as the cutoff for filtering API messages. Due to async execution during streaming (tool execution happens concurrently with stream completion), a clineMessage could have a timestamp BEFORE the corresponding assistant API message. This caused the assistant message to be incorrectly removed.

Timeline Example (Bug Scenario)

Timestamp	Message Type	Expected
T1=100	clineMessage "user_feedback"	Delete
T2=200	API assistant (tool_use)	Keep
T3=300	API user (tool_result)	Delete

With the old logic (ts < 100), both API messages at T2 and T3 were removed.

Solution

Modified src/core/message-manager/index.ts to detect the race condition scenario by checking:

1. If there's no exact timestamp match between clineMessage and API messages
2. If there are messages before the cutoff that should be preserved

When both conditions are true (indicating a race condition), the fix finds the first API user message at or after the cutoff and uses that as the actual boundary. This ensures assistant messages that logically preceded the user's response are preserved.

Changes

• src/core/message-manager/index.ts - Added race condition detection and handling in truncateApiHistoryWithCleanup
• src/core/message-manager/index.spec.ts - Added 4 new test cases covering:
  • Race condition scenario (clineMessage timestamp earlier than assistant API message)
  • Normal case (timestamps properly aligned)
  • Fallback when no user message found at or after cutoff
  • Multiple assistant messages in race condition

---

Important

Fixes race condition in message deletion logic by adjusting cutoff timestamp handling in truncateApiHistoryWithCleanup to ensure correct message preservation.

• Behavior:
  • Fixes race condition in truncateApiHistoryWithCleanup in index.ts by adjusting cutoff timestamp logic to preserve assistant messages when clineMessage timestamp is earlier.
  • Uses first API user message at or after cutoff as boundary if no exact match and messages exist before cutoff.
• Tests:
  • Adds 4 test cases in index.spec.ts for race condition handling, normal timestamp alignment, fallback when no user message at or after cutoff, and multiple assistant messages in race condition.

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[roomote]

Oroocle   See task on Roo Cloud

Re-review complete. No new issues found in the latest changes; the existing follow-up item remains.

• Tighten/gate the new actualCutoff heuristic in truncateApiHistoryWithCleanup so it does not change semantics for non-race rewinds (e.g. assistant-message rewinds where the next API user message is much later).

Previous reviews

• acc5567: Review #1
• 51858f3: Review #2

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}