fix(web): filter AI usage-limit 402 errors out of Sentry

[eshurakov]

Summary

Filters AI_APICallError with statusCode: 402 out of Sentry in beforeSend, alongside the existing tRPC 4xx filter.

Why

The AI gateway returns 402 (usage_limit_exceeded — "Add credits to continue, or switch to a free model", llm-proxy-helpers.ts) when the caller's own credit balance is exhausted. Server-side callers acting on behalf of a user — e.g. Kilo Bot processing /api/internal/bot-session-callback — surface this as an unhandled AI_APICallError (statusCode 402), which captureException then reports. Each event just means "a user ran out of credits mid-workflow": expected per-user billing state, not an application bug, and it scales with free/low-credit usage.

This is safe to filter globally because upstream provider 402s (our provider account) never reach AI SDK callers: the gateway converts them to a 503 and reports them itself via captureProxyError({ trackInSentry: true }) in app/api/openrouter/[...path]/route.ts, so that failure mode stays visible.

Changes

• apps/web/sentry.server.config.ts: add exported isAIUsageLimitError predicate (duck-typed like the existing isTRPC4xxError, so the ai package stays out of the Sentry init bundle) and apply it in beforeSend.
• apps/web/src/sentry.server.config.test.ts: tests for the predicate, including one built from the real APICallError class to pin the duck-type contract.

Verification

• jest src/sentry.server.config.test.ts: 24/24 pass (run with a scratch config identical to jest.config.ts minus the DB-backed global setup — this sandbox has no Docker/Postgres; the standard config's setup requires it. The suite itself has no DB dependency, so CI should behave the same).
• oxlint on the changed test file: clean.
• oxfmt applied to both files.
• Scoped tsgo typecheck of both changed files: clean. Full apps/web typecheck not run (its @kilocode/trpc build prerequisite exceeded the sandbox time limit).

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

Reviewed the Sentry beforeSend filter for AI usage-limit 402 errors and its tests; the duck-typed predicate is type-safe, the claim that upstream provider 402s are converted to 503 and reported separately was verified against the gateway route, and no platform-side 402 path is hidden by the filter.

Files Reviewed (2 files)

• apps/web/sentry.server.config.ts
• apps/web/src/sentry.server.config.test.ts

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_{Reviewed by kimi-k3 · Input: 62.1K · Output: 13.5K · Cached: 633.9K}

_{Review guidance: REVIEW.md from base branch main}

[chrarnoldus]

Would it be better to fix the source?