bug: API conversation history file truncated to empty array during task resume

[KJ7LNW]

When resuming a task while opening and closing orchestrator tasks, the API conversation history file is sometimes truncated to an empty array [].

I am speculating that there was a race condition which caused multiple simultaneous writes to api_conversation_history.json when I was clicking between tasks, and #3772 will probably fix this because it is atomic and has a lock to prevent simultaneous activity on the same file.

Error

mainThreadExtensionService.ts:78 [RooVeterinaryInc.roo-cline]Unexpected: No existing API conversation history
mainThreadExtensionService.ts:79 Error: Unexpected: No existing API conversation history
    at _Task.resumeTaskFromHistory (vscode-file://vscode…task/Task.ts:922:10)
log.ts:460   ERR An unknown error occurred. Please consult the log for more details.

Debug Information

Added debug logging shows that the file exists but contains an empty array:

[Roo-Debug] readApiMessages: Found API conversation history file, but it's empty. TaskId: 33369d03-10fb-436e-a708-ec3cdde71d80, Path: ~/.config/Code - Insiders/User/globalStorage/rooveterinaryinc.roo-cline/tasks/33369d03-10fb-436e-a708-ec3cdde71d80/api_conversation_history.json

Reproduction Steps

1. Open a task
2. Open an orchestrator task from within that task
3. Close the orchestrator task
4. Attempt to resume the original task

Potential Fix

PR #3772 (#3772) may address this issue, though the exact cause is still unknown.

Impact

This causes task resumption to fail with the error "Unexpected: No existing API conversation history" and prevents users from continuing their work.

[hannesrudolph]

I feel like this issue needs to be dug into more and that the PR to add the logging in not the answer though whoever is working on this would find that PR helpful to load up and try and trigger this with repro steps.

[KJ7LNW]

the PR to add the logging in not the answer

That is absolutely true it is not intended to be the answer, and it probably should not close the issue---however it may help others to get some debug and save someone time in troubleshooting if they had the same problem.