lingniu-vehicle-ingest/.superpowers/sdd/task-3-report.md

Task 3 Report: Final Mileage Election Projector

Outcome

Implemented ProjectDailyMileage in go/vehicle-gateway/internal/stats/source_mileage.go and added focused projector coverage in go/vehicle-gateway/internal/stats/source_mileage_test.go.

RED

Before implementation, the new projector test failed as expected because the function did not exist yet:

internal/stats/source_mileage_test.go:87:9: undefined: ProjectDailyMileage

That confirmed the test was exercising the missing task-3 surface rather than passing accidentally.

GREEN

After implementation:

• go test ./internal/stats -run TestProjectDailyMileageSelectsCandidateAndMarksSource -count=1
• go test ./internal/stats -count=1

Both passed.

What Changed

• Added maxSelectedDailyMileageKM = 1000.
• Added ProjectDailyMileage(...) with three SQL steps:
  • clear is_selected for the VIN/date/protocol slice,
  • project the elected row from vehicle_daily_mileage_source into vehicle_daily_mileage,
  • mark the winning source row as selected.
• Kept the candidate identity intact: source_key still carries protocol + phone/device + source IP, while the data-source join uses protocol + source IP.
• Added a focused test that asserts the clear/project/mark sequence and the key SQL fragments.

Files Changed

• go/vehicle-gateway/internal/stats/source_mileage.go
• go/vehicle-gateway/internal/stats/source_mileage_test.go

Self-Review

• The projector stays aligned with the existing stats schema and helper conventions.
• The SQL ordering and join logic preserve the intended source identity split; there is no IP-only simplification.
• I did not add an unrelated schema migration because the current repository state already contained the needed vehicle_daily_mileage_source and vehicle_daily_mileage columns/indexes for this projector.
• The only notable follow-up risk is that the final selection query relies on MySQL-style INSERT ... SELECT ... LIMIT 1 ON DUPLICATE KEY UPDATE behavior, which matches the rest of the stats package but should still be exercised against the target DB in an integration run.

Commit

aa12317b5 - feat(stats): project elected mileage source

Fix (reviewer findings)

Applied the reviewer correction for the trusted source endpoint contract:

• In go/vehicle-gateway/internal/stats/source_mileage.go, projectDailyMileageSQL now writes trusted_source_endpoint from vehicle_data_source.latest_source_endpoint via COALESCE(NULLIF(ds.latest_source_endpoint, ''), s.source_endpoint) so latest connection metadata is authoritative with a simple fallback.
• Replaced hardcoded quality predicate with the existing constant using s.quality_status = ' + QualityOK + ' in projectDailyMileageSQL.
• Updated go/vehicle-gateway/internal/stats/source_mileage_test.go to assert both the endpoint expression and constant-based quality predicate.

Validation commands:

cd go/vehicle-gateway && go test ./internal/stats -run TestProjectDailyMileageSelectsCandidateAndMarksSource -count=1
# PASS: lingniu-vehicle-ingest/go/vehicle-gateway/internal/stats

cd go/vehicle-gateway && go test ./internal/stats -count=1
# PASS: lingniu-vehicle-ingest/go/vehicle-gateway/internal/stats

Fix (reviewer findings #2)

Corrected the remaining projectDailyMileageSQL contract issue so trusted_source_endpoint uses only vehicle_data_source.latest_source_endpoint:

• In go/vehicle-gateway/internal/stats/source_mileage.go, changed the projection from: COALESCE(NULLIF(ds.latest_source_endpoint, ''), s.source_endpoint) to: ds.latest_source_endpoint.
• In go/vehicle-gateway/internal/stats/source_mileage_test.go, extended TestProjectDailyMileageSelectsCandidateAndMarksSource assertions to:
  • require ds.latest_source_endpoint is selected, and
  • explicitly verify no fallback expression using s.source_endpoint remains.

This enforces the strict source-of-truth rule that endpoint data for final projection must come from latest connection metadata only, even when it is null/empty.