fix(export): prefix CSV data keys that collide with id/timestamp/duration

[TimeToBuildBob]

The bucket CSV export (#722) writes id,timestamp,duration followed by the union of event data keys. A data key named id, timestamp or duration produced a duplicate header name, so the columns were unambiguous by position but not by name. Greptile flagged this on ActivityWatch/aw-server#178.

Fix: a data key that would repeat an earlier header name gets a data. prefix, repeated until unique (duration → data.duration; data keys arrive sorted, so a literal data.id key keeps data.id and the id key becomes data.data.id). Only the header changes; values are still read by the original key. Keys that don't collide are unchanged, and the >32-key single data JSON column is unaffected.

A matching aw-server (Python) PR follows so both servers emit the same header.

Tests: new csv_header_prefixes_data_keys_that_collide_with_columns (header) and streamed_csv_prefixed_columns_carry_original_key_values (full export, header↔row); cargo test -p aw-datastore --lib export 16 passed, the aw-server CSV API test passes, fmt and clippy clean.

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Changes how CSV export columns are named.

The PR appears safe to merge, with no outstanding findings.

Summary

The PR gives colliding CSV data headers a repeated data. prefix while keeping value lookup tied to the original keys.

• The change since the last review adds a full-export test that checks reserved fields and all four colliding data keys.
• This addresses the previous request to test that renamed columns contain the right values.
• No new actionable issues were found. Tests were not run during this review.

_{Reviews (2) · Last reviewed commit: "test(export): check prefixed CSV columns..."}

[TimeToBuildBob]

@greptileai review

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.96%. Comparing base (656f3c9) to head (292b112).
⚠️ Report is 185 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #795       +/-   ##
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+ Coverage   70.81%   83.96%   +13.14%     
===========================================
  Files          51       82       +31     
  Lines        2916    10806     +7890     
===========================================
+ Hits         2065     9073     +7008     
- Misses        851     1733      +882     

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[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.

[TimeToBuildBob]

🤖 AI code review

Adds csv_header_names(), which renames data keys that collide with the fixed id/timestamp/duration columns by prepending data. until the name is unique, and routes write_csv_header through it while value rows still read by the original key. Adds two tests covering the rename logic and header-to-row alignment for prefixed columns in a streamed export.

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-datastore/src/export.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-datastore/src/export.rs — Adds csv_header_names() that prefixes colliding data keys with data.; writes headers through it; adds two tests for prefixing and value alignment.

_{Reviewed 292b1124a9d1 · openrouter/deepseek/deepseek-v4-flash-0731 · llm engine · 901s · about this reviewer}

_{Maintainer commands}

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