Separate rate-budget accounting by authentication context - #29
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The budget gate held one REST ResourceBudget for two GitHub pools: App JWT (~5,000/hr for the app) and installation tokens (15,000/hr on GHEC). Their x-ratelimit headers overwrote each other's shared admission state, so during the 2026-08-04 incident ghsync reported remaining budget and kept admitting while GitHub returned rate limit exceeded for the installation. Budget state is now keyed by credential context. Every request path declares its context -- repository REST and GraphQL as installation auth; delivery list/redelivery as App JWT; installation-token MINT calls as App JWT (they authenticate with the App JWT even though they produce installation tokens), admitted inside the outer request's concurrency slot. Header observations update only their own context; floors, secondary backoff, and admission are per-context, so a JWT backoff cannot starve installation-class traffic or vice versa. The lease snapshot persists both contexts as additional installation_ budgets class rows (text keys; existing rest/graphql rows remain valid, no migration). C-B3 metrics gain an auth_context label with ops/alerts.yaml and ops/DASHBOARD.md expressions updated to match. A deterministic scripted-response regression proves conflicting concurrent headers from both contexts produce correct admission for each -- the merged-header masking failure mode. Fixes #25 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Fixes #25 — App-JWT and installation-token traffic no longer share one REST budget state.
ResourceBudget(installation REST / App-JWT REST / GraphQL), with per-context floors, secondary backoff, and admission; header observations update only their own context.installation_budgetsclass rows — migration-free, upgraded databases keep valid rows.auth_contextlabel;ops/alerts.yamlandops/DASHBOARD.mdupdated so no expression references the dead unlabeled series.Built and adversarially reviewed by paired Codex sol-xhigh agents in a dedicated worktree (parallel with #26/#27/#28). Full gate green locally.
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