refactor: log best-effort cleanup failures instead of swallowing them

[bhekanik]

What

Routes three best-effort cleanup calls in the mutation handler through a new log_non_fatal helper instead of discarding their errors with let _ = …. Audit backlog item P2 #19 (swallowed-error sweep). Off main.

Why

A silent cleanup failure hides real state drift:

• a sent draft that fails to delete lingers in mxr drafts list;
• an undo entry that fails to delete after a successful undo stays replayable until it expires;
• an expired undo entry that fails to delete just accumulates.

None of these should abort the caller, but they shouldn't vanish either.

How

A small log_non_fatal(context, result) helper logs Err as a warn with context and otherwise does nothing. Applied to the three delete_undo_entry / delete_draft cleanups.

Scope note (honest)

The audit framed this as a broad sweep, but a survey of let _ = …await across the daemon found only these three are store writes whose failure is meaningful — the rest are genuine fire-and-forget (channel sends, broadcast, notify) that are correct to ignore. So the change is deliberately narrow rather than a blanket rewrite.

Verification

mxr daemon undo/mutation tests (95) pass; clippy + fmt clean. No user-facing contract change (internal observability), so no docs update.

Generated with Claude Code

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Summary by cubic

Log best-effort cleanup failures in the mutation handler instead of swallowing them. Warnings now surface when deleting expired/spent undo entries or sent drafts fails, preventing silent state drift (lingering drafts or replayable undo IDs) while keeping these errors non-fatal.

^{Written for commit 72e2365. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes
  • Enhanced error logging for background cleanup operations in data management workflows, improving system diagnostics and reliability without affecting user-facing functionality.

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Project	Deployment	Actions	Updated (UTC)
mxr-mail	Ready	Preview, Comment	Jun 10, 2026 8:17pm

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fa9cac03-f328-4d90-a99f-5465d2b95ba3

📥 Commits

Reviewing files that changed from the base of the PR and between 7bb7a09 and 72e2365.

📒 Files selected for processing (1)

• crates/daemon/src/handler/mutations.rs

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📝 Walkthrough

Walkthrough

This PR introduces a log_non_fatal helper function to emit warnings when best-effort cleanup operations fail. The helper is then applied to three mutation cleanup sites: expired-undo deletion, post-success undo deletion, and draft deletion after send. Cleanup failures are now logged but do not affect operation success.

Changes

Non-fatal cleanup logging

Layer / File(s)	Summary
log_non_fatal helper definition crates/daemon/src/handler/mutations.rs	log_non_fatal is a generic helper that logs tracing::warn! when a best-effort Result is Err, preserving non-fatal cleanup semantics.
Apply logging to undo and draft cleanup crates/daemon/src/handler/mutations.rs	Three cleanup sites in undo_mutation and send_stored_draft now call log_non_fatal(...) instead of silently discarding delete operation results, so deletion failures are warned about while the operations continue unaffected.

🎯 2 (Simple) | ⏱️ ~5 minutes

🐰 A helper hops through the code with care,
Warning us when cleanups fail to fare.
Three mutations now log their might,
Keeping best-effort work in sight!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'refactor: log best-effort cleanup failures instead of swallowing them' accurately and specifically describes the main change: adding logging for previously silent cleanup errors in mutation handlers.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/log-non-fatal-cleanup-errors

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[cubic-dev-ai]

No issues found across 1 file

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