feat: cross-machine usage aggregation with device-level dedup

[Yeachan-Heo]

Summary

• Ports the device-level deduplication logic from PR feat: cross-machine usage aggregation + automatic sync #55 (feat/cross-machine-aggregation-sync) into the current client-based codebase structure
• Each client (e.g., "claude", "cursor") now tracks per-device contributions via a devices field keyed by API token ID
• On resubmit from the same device, only that device's data is replaced — other devices' data is preserved, preventing double-counting
• Legacy data (without device tracking) is gracefully migrated to a __legacy__ device key on first merge
• Client-level totals and model breakdowns are recalculated from the sum of all devices

Changes

• helpers.ts: Added DeviceClientData interface, devices? field on ClientBreakdownData, recalculateClientAggregate helper, and updated mergeClientBreakdowns to accept deviceId and perform device-level merge with legacy migration
• route.ts: INSERT path now initializes devices[tokenId] from the start; UPDATE path passes tokenRecord.tokenId to the merge function
• schema.ts: Added devices? to the sourceBreakdown JSONB type definition
• submit.test.ts: Added 8 new tests covering device-level dedup scenarios (resubmit, multi-device aggregation, legacy migration, device removal, cross-device model aggregation, multi-client multi-device)

Test plan

• All 28 tests pass (20 existing + 8 new device-level dedup tests)
• No TypeScript errors in modified files
• Manual verification: submit from device A, submit from device B, verify totals = A + B
• Manual verification: resubmit from device A with updated data, verify totals = A' + B (not A + A' + B)
• Verify backward compatibility with existing data (no devices field) — should auto-migrate to __legacy__

🤖 Generated with Claude Code

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Summary by cubic

Add per-device usage tracking and dedup to client aggregation to support cross‑machine submissions. Resubmits now replace only that device’s data, preventing double counting and keeping totals accurate.

• New Features
  • Track per-device contributions in client breakdowns via devices[tokenId]; mergeClientBreakdowns now replaces only the submitting device and recalculates aggregates.
  • POST /api/submit initializes devices[tokenId] on insert and passes tokenId on update to avoid legacy paths and resubmit inflation.
  • Legacy data auto-migrates to a legacy device on first merge; client totals and model breakdowns are rebuilt from device data.
  • Schema adds devices to sourceBreakdown; 8 tests cover resubmit, multi-device aggregation, legacy migration, device removal, and cross-device model sums.

^{Written for commit 556afd9. Summary will update on new commits.}

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[cubic-dev-ai]

1 issue found across 4 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/frontend/src/lib/db/helpers.ts">

<violation number="1" location="packages/frontend/src/lib/db/helpers.ts:222">
P2: Legacy incoming payloads that only provide modelId (no models) will drop model-level attribution after recalculation because device contributions only copy incomingClient.models. recalculateClientAggregate rebuilds client.models exclusively from device.models, so legacy modelId data is lost.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}