[TimeToBuildBob]

union_no_overlap walks both lists in ascending timestamp order, but query_bucket returns events newest-first, and the query function passes its arguments through unsorted. The result then contains overlapping events and durations are double-counted.

Repro against a v0.14.1 --testing server: window and AFK buckets that each fully cover the same 40 minutes.

union_no_overlap(query_bucket("w"), query_bucket("afk"))                                  -> sum_durations 4200.0
union_no_overlap(sort_by_timestamp(query_bucket("w")), sort_by_timestamp(query_bucket("afk"))) -> sum_durations 2400.0

aw-webui hits this path with raw bucket output:

• canonicalEvents: stopwatch_events = query_bucket(...) then union_no_overlap(stopwatch_events, events)
• activityQuery: not_afk_curr = filter_keyvals(query_bucket(...), ...) then union_no_overlap(not_afk, not_afk_curr), once per AFK bucket. With two or more devices the total is inflated.

The fix sorts both inputs inside the transform, as period_union and filter_period_intersect already do. Inputs that are already sorted produce the same output as before.

Test: newest_first_inputs_are_sorted_before_merging feeds reversed lists. It fails without the sort (six overlapping spans) and passes with it. cargo test -p aw-transform -p aw-query passes and cargo fmt --check is clean.

aw-core's Python union_no_overlap documents sorted input as a precondition and has the same exposure, so it needs a matching change.

[greptile-apps]

Confidence Score: 5/5

[Medium impact] This PR appears safe to merge.

Summary

union_no_overlap now sorts both inputs before merging, so newest-first events no longer cause double-counted durations.

• The event-union transform sorts both lists before merging.

_{Reviews (1) · Last reviewed commit: "fix(transform): sort union_no_overlap in..." · Reviewed by Greptile}

[TimeToBuildBob]

🤖 AI code review

In aw-transform/src/union_no_overlap.rs, union_no_overlap now calls sort_by_timestamp on both inputs before creating the merge iterators, and its documentation describes this ordering step. The new newest_first_inputs_are_sorted_before_merging test compares reversed inputs with ascending inputs, checks union invariants, and asserts a total duration of 40 minutes.

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No thread-worthy findings. Advisory notes follow; they are retained without opening review threads.

1 advisory finding (summary-only, not scored)

These P2 guard, heuristic, trade-off, or documentation claims are retained for judgment without opening review threads.

⚠️ P2 medium — aw-transform/src/union_no_overlap.rs

This is a fix(...) PR but no test files are included in the diff. Erik's feedback: 'where is the repro & fixes they are supposed to catch' (gptme#3441), 'that measurement should come with a regression test' (gptme#3446). Add a test that would have caught this bug. (Advisory: Erik merged all such PRs but consistently requested tests.)

Add a test file that reproduces the bug before the fix and passes after it.

_{How this was verified: static preflight: fix-commit + touched-files scan (rule 7)}

Files changed (1) — the diff as I read it

• aw-transform/src/union_no_overlap.rs — Imports sort_by_timestamp, sorts both merge inputs, documents the ordering step, and adds a regression test using newest-first event lists.

Previous review passes

commit	score	findings	engine	when
15cdf1a86f72	5/5	0	subscription	2026-10-26 04:42 UTC

_{Reviewed 15cdf1a86f72 · panel: codex:gpt-6.1-sol + claude-code:sonnet + grok-build:grok-4.6 · subscription engine · 16s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}

The optional OpenRouter verifier was unavailable. Findings retain their original severity.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.42%. Comparing base (656f3c9) to head (15cdf1a).
⚠️ Report is 219 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #838       +/-   ##
===========================================
+ Coverage   70.81%   85.42%   +14.61%     
===========================================
  Files          51       88       +37     
  Lines        2916    12613     +9697     
===========================================
+ Hits         2065    10775     +8710     
- Misses        851     1838      +987     

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[TimeToBuildBob]

The missing-test advisory is a false positive: this diff adds the inline Rust regression test newest_first_inputs_are_sorted_before_merging in aw-transform/src/union_no_overlap.rs. No extra test file is needed. All eight checks are green, and Greptile reports 5/5. No code change needed; waiting for a maintainer merge (Bob has triage, not push permission). The matching Python fix is ActivityWatch/aw-core#185.

[TimeToBuildBob]

CI-green and mergeable (Greptile 5/5) — waiting only on a maintainer click.

This PR is ready to merge, but the bot has pull-only access to this repo and can't self-merge — surfacing it here so it isn't lost. The monitoring loop will stop re-flagging it now that this note is posted.