Fix over-eager dive matching (time gate) + Consolidate for file imports

[ericgriffin]

Addresses a tester report on ScubaBoard (user stiebs): a Subsurface import was flagged as a 50% "possible duplicate" of an existing dive that was months apart, ~4.5 km away, at a different time of day — sharing only its 47-minute duration. The same report noted that Combine/Consolidate only worked for direct dive-computer downloads, not file imports.

Part 1 — Time is now a necessary gate in the matcher

File imports score candidates with DiveMatcher.calculateMatchScore, a weighted sum: time*0.50 + depth*0.30 + duration*0.20. With timeScore = 0 (starts >= 15 min apart), depth (0.30) + duration (0.20) alone summed to exactly 0.50 — the isPossibleDuplicate threshold — so two unrelated dives with a similar profile got flagged.

A dive is a single event in time; two recordings that do not line up in time cannot be the same dive. The fix makes time a necessary condition: once time evidence is zero, the pair is not a match, before the weighted sum runs. The dive-computer download path already gated on time via SQL, so it is unchanged.

stiebs's pair now scores 0.0 instead of 0.50.

Part 2 — Manual Consolidate for file imports

The consolidation capability already existed but was only wired into the dive-computer download adapter; the live file-import adapter (UniversalAdapter) offered only skip / import-as-new and hard-coded consolidatedCount: 0. This ports the proven wiring (performConsolidations + DiveConsolidationService) into UniversalAdapter:

• consolidate added to supportedDuplicateActions → the review UI renders the button automatically (one declarative set drives every layer of the UI).
• Exact source_uuid re-imports are flagged matchedExistingSource so they default to skip (never consolidated).
• performImport folds consolidate-flagged dives after import and reports an accurate count — folded dives are subtracted from the "imported as new" count instead of being double-counted.

File imports are manual-consolidate only: a file has no single "current computer" to prove a cross-computer match, so the user chooses. Consolidating onto a same-computer target fails gracefully (the fold is rejected, the standalone import is tombstoned via the existing compensating-delete path, and it is reported as skipped).

Testing

• DiveMatcher: gate tests incl. the exact ScubaBoard regression (months apart, identical depth + duration → 0.0), same-day-hours-apart, the 15-minute boundary, and a within-window guard.
• ImportDuplicateChecker: matchedExistingSource true for source_uuid / false for content matches; far-apart dives no longer matched.
• UniversalAdapter: supports consolidate; performImport folds a consolidate-flagged dive and adjusts counts (wiring test).
• Full suite green: 10449 passed / 12 skipped; flutter analyze clean (whole project); macOS build succeeds.

Design spec and implementation plan are included under docs/superpowers/.

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[Copilot]

Pull request overview

This PR tightens duplicate-dive detection for file imports by making time proximity a hard prerequisite in DiveMatcher, and it wires manual “Consolidate” support into the routed file-import adapter (UniversalAdapter) so file imports can fold duplicates the same way dive-computer downloads can.

Changes:

• Make time a necessary gate in DiveMatcher.calculateMatchScore so far-apart dives can’t reach duplicate thresholds via depth+duration alone.
• Flag exact source_uuid re-import matches as matchedExistingSource and enable manual DuplicateAction.consolidate for file imports, including post-import folding and corrected summary counts.
• Add targeted regression and wiring tests, plus design/spec documentation under docs/superpowers/.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/features/universal_import/data/services/import_duplicate_checker_test.dart	Adds tests for matchedExistingSource semantics and far-apart dives no longer matching.
test/features/import_wizard/data/adapters/universal_adapter_test.dart	Verifies consolidate is supported and performImport delegates fold + adjusts counts.
test/features/dive_import/domain/services/dive_matcher_test.dart	Adds time-gate regression/boundary tests for matcher scoring.
lib/features/universal_import/data/services/import_duplicate_checker.dart	Sets matchedExistingSource: true for exact source_uuid matches.
lib/features/import_wizard/data/adapters/universal_adapter.dart	Enables consolidate for file imports and performs post-import consolidation with updated result accounting.
lib/features/dive_import/domain/services/dive_matcher.dart	Implements the time-as-gate short-circuit in calculateMatchScore.
docs/superpowers/specs/2026-07-06-dive-matching-time-gate-and-file-import-consolidation-design.md	Design spec documenting the two fixes and rationale.
docs/superpowers/plans/2026-07-06-dive-matching-time-gate-and-file-import-consolidation.md	Implementation plan for the work (for traceability/process).