[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 aw-server-rust --testing server (this module ports the same algorithm): 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: test_newest_first_inputs_are_sorted_before_merging feeds reversed lists. It fails without the sort and passes with it. The full pytest tests suite passes (359 passed, 5 skipped) and ruff check is clean.

Counterpart of ActivityWatch/aw-server-rust#838. The Python server is what aw-qt autostarts in the v0.14.1 Qt bundle, so this is the path most desktop users hit.

Also reproduced live on the released Python aw-server v0.14.1 (--testing, isolated home), using the same buckets: unsorted 4200.0, sorted 2400.0. A chained activityQuery-style union (a = []; a = union_no_overlap(a, afk); a = union_no_overlap(a, window)) returns 3600.0 where the correct coverage is 2400.0.

[greptile-apps]

Confidence Score: 5/5

[Medium impact] This PR appears safe to merge.

Summary

union_no_overlap now sorts copied inputs by timestamp before merging, so newest-first events no longer cause double-counting.

• Event unions sort both inputs before removing overlaps.

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[TimeToBuildBob]

CI-green and mergeable — 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.

[TimeToBuildBob]

🤖 AI code review

The PR changes union_no_overlap to sort deep copies of both input lists by Event.timestamp before merging and updates its docstring to describe this behavior. It adds a regression test comparing ascending and newest-first inputs, checking union invariants and a total duration of 40 minutes.

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No findings. The diff looks correct to me on this pass.

Files changed (2) — the diff as I read it

• aw_transform/union_no_overlap.py — Sorts both copied input lists by timestamp before merging and updates the input-order documentation.
• tests/test_union_no_overlap.py — Adds test_newest_first_inputs_are_sorted_before_merging to compare reversed inputs with ascending inputs and check invariants and total duration.

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Outage coverage: 1-pass, not merge evidence. Subscription review supplied findings while full consensus capacity was unavailable. The consensus merge gate remains unsatisfied.