fix: propagate score_lines errors, fix compact response shape (CodeRabbit follow-up)

[getappz]

Summary

Follow-up addressing 2 CodeRabbit findings from the PR #193 review that were on src/compact.rs/src/memory/mcp.rs (unrelated to #193's actual scope — that code came from an earlier duplicate branch and was reconciled against the already-merged, already-fixed version from #192/#195; these 2 are new findings against that merged code).

• score_lines() used .expect() on every SQLite call (connection, table create, insert, query) and would panic on any SQLite failure, even though handle_compact (its only non-hook caller) already returns a Result. Now returns rusqlite::Result<Vec<ScoredLine>> and propagates. The PreCompact hook caller has no Result to propagate through, so it fails soft (skips output) on error, consistent with its existing degrade-gracefully pattern for a missing/unreadable transcript.
• handle_compact's empty-entries early-return response ({"lines": [], "kept": 0, "total": 0}) was missing the "query" field the full response includes — a client relying on a consistent response shape could break on the empty-input path. Added it.

Test plan

• cargo test --workspace — all passing, new regression test for the response-shape fix
• cargo clippy --workspace --all-targets -- -D warnings -A unsafe_code -A clippy::pedantic — clean
• cargo fmt --check — clean

Summary by CodeRabbit

• Bug Fixes
  • Improved error handling during line scoring to prevent crashes when database or query operations fail.
  • Compaction now safely stops when scoring cannot be completed.
  • Empty compaction responses now consistently include the submitted query.
• Tests
  • Added coverage for query details in empty compaction responses and updated scoring tests for error handling.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: fe6574ef-7419-4480-b6b5-10bda53ef86b

📥 Commits

Reviewing files that changed from the base of the PR and between be22ffc and 094edd5.

📒 Files selected for processing (3)

• src/compact.rs
• src/hook.rs
• src/memory/mcp.rs

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📝 Walkthrough

Walkthrough

Compact scoring now returns SQLite errors instead of panicking, and callers handle failures explicitly. Empty compaction responses now retain the input query, with tests updated for both behaviors.

Changes

Compact scoring and response handling

Layer / File(s)	Summary
Fallible scoring API src/compact.rs	score_lines returns rusqlite::Result, propagates SQLite and row-mapping errors, and tests unwrap successful results.
Caller errors and empty responses src/hook.rs, src/memory/mcp.rs	pre_compact exits when scoring fails, while empty handle_compact responses include and test the supplied query.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• getappz/agentflare#192: Introduces the related score_lines BM25/FTS5 functionality modified here.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: error propagation in score_lines and the compact response shape fix.
Description check	✅ Passed	The description covers the required Summary and Test plan sections; the reviewer notes section is missing but non-critical.
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.

✨ 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 fix/compact-error-propagation-and-response-shape

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