🤖 tests: characterize session usage repricing in WorkspaceStore

[ThomasK33]

Summary

Adds characterization tests for how WorkspaceStore reprices loaded session usage. They pin which rows keep their recorded costs (gateway-billed rows) and which rows get the current model pricing. Test-only change, no production code changes.

Background

This PR is part of the CRAP code-quality campaign. isCostsIncludedEntry in src/browser/stores/WorkspaceStore.ts had CC 18 and no test reached it (CRAP 342, the highest score in the file). With these tests, merged CI coverage plus a local run scores it at 100% coverage, CRAP 18.

Implementation

The tests go through the public store surface: a getSessionUsage response, the provider config (providers.getConfig, onConfigChanged), and getWorkspaceUsage().sessionByModel / .lastRequest. They cover:

• stale recorded costs are repriced (one non-zero component is enough);
• costsIncluded: true keeps zero costs, and it wins over hasUnknownCosts;
• legacy all-zero rows of a billable model stay zero (no unknown-cost flag);
• hasUnknownCosts: true rows get priced;
• all-zero rows of an unpriced model are repriced (they get flagged as unknown, not treated as gateway-billed);
• a mapped custom model is classified by the pricing of its mapped model;
• a provider config change that adds a mapping prices rows that were unknown before.

Each workspace gets a caught-up chat first. Before catch-up, getWorkspaceUsage serves the pre-replay snapshot, which would hide the repriced rows.

Validation

• 8 mutants of isCostsIncludedEntry and its repriceSessionUsage call sites (drop each check, swap the marker order, use the raw model for pricing, check only the input cost, never set hasTokens, ignore the marker for lastRequest): every mutant fails at least one new test.

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Generated with xum • Model: anthropic:claude-opus-5-5 • Thinking: high

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-13T08:24:43.421875Z	3b3287f	PR opened
🔒 Security Review	✅ Completed 2026-10-13T08:25:05.810886Z	3b3287f	PR opened

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