fix: make task error_message clearable

[bsbodden]

Summary

• Use a sentinel default for error_message in update_task_status to distinguish "not provided" from "clear the field"
• Passing error_message="" now clears a previously set error to None
• Omitting the argument leaves the existing value unchanged

Changes

• agent_memory_server/tasks.py: Replace None default with _UNSET sentinel, treat empty string as clear
• tests/integration/test_task_error_message_clearable.py: 3 tests covering clear, no-change, and replace behavior

Test plan

• All 3 new integration tests pass
• Full existing test suite passes (710 passed, 0 failures)

Closes #206

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Note

Low Risk
Low risk, localized change to update_task_status semantics plus a regression test; main risk is behavioral change for callers that previously relied on passing None to clear the field.

Overview
Fixes task error handling so update_task_status can distinguish “not provided” from “clear the field” by introducing an _UNSET sentinel default for error_message.

Passing error_message="" (or None) now clears Task.error_message to None, while omitting error_message leaves any existing value unchanged. Adds an integration regression test covering clear/no-change/replace behavior.

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[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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^{Security scan by Jit}

[github-actions]

Review completed. Found one potential issue with the error_message handling logic that could lead to unexpected behavior when explicitly passing None.

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[Copilot]

Pull request overview

Updates task status updating logic so callers can clear an existing Task.error_message (previously “sticky”) while preserving the ability to omit the parameter and leave the stored value unchanged.

Changes:

• Introduce an _UNSET sentinel default for error_message in update_task_status to distinguish “not provided” vs “provided”.
• Interpret error_message="" as a request to clear the stored error message (None).
• Add integration tests covering clear / no-change / replace behaviors.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
agent_memory_server/tasks.py	Adds _UNSET sentinel and updates update_task_status to support clearing error_message.
tests/integration/test_task_error_message_clearable.py	Adds regression coverage for clearing vs leaving error_message unchanged.

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[justin-cechmanek]

👍🏼