## What
Rate-limit the API by **environment** rather than per API key.
Previously the limiter keyed its bucket on the hash of the full
`Authorization` header — one bucket per key. With additional environment
API keys (`tr_*_sk_*`), an environment can mint many keys and each got
its own full bucket, so more keys = higher effective rate limit. This
collapses all of an environment's keys onto a single shared
per-environment bucket, so the ceiling is exactly the configured limit
regardless of key mix.
## How
- `authorizationRateLimitMiddleware` now lets the override return `{
config?, identifier? }`. `identifier`, when present, is the rate limit
bucket key; otherwise it falls back to the hashed `Authorization` header
(unchanged legacy behavior, still used by `engineRateLimiter` and any
unauthenticated fallthrough).
- `apiRateLimiter`'s override resolves the environment id and uses it as
the identifier:
- **Additional keys** (`isAdditionalApiKey`) resolve via a new
`resolveAdditionalApiKeyRateLimitScope()` — a **scope-agnostic** keyHash
→ (environmentId, org limiter config) lookup. It is deliberately
permissive (restricted keys resolve too) because it's used **only for
bucketing, never as an auth decision** — request auth still goes through
the RBAC bearer controller, which enforces scopes. Revoked/expired keys
are excluded so they can't hold a bucket warm.
- **Root/legacy keys** reuse the environment already resolved by
`authenticateAuthorizationHeader` and key on `environment.id` too.
- The identifier is always the stable environment id, never the secret
key (which can rotate and would split the bucket).
- The whole override result is cached per key by the existing SWR cache,
so **no extra per-request lookup and no separate Redis mapping** is
added.
## Behavior notes
- Root + additional keys of the same environment now share one bucket
(ceiling = configured limit, not a multiple of it). Restricted
additional keys are included — they were the biggest gap, since they
authenticate via the RBAC controller and previously fell back to per-key
buckets.
- **Public JWTs** keep their existing fixed-window, per-token bucketing.
- One-time bucket reset on deploy (bucket keys change); harmless.
## Tests
- New: two tokens resolving to the same identifier share one bucket.
- New: with no identifier, bucketing stays per-key (legacy behavior
preserved).
- Updated existing override tests to the new `{ config }` return shape.
Base: `feat/multi-keys-surface`. Closes TRI-12888.
Chris Arderne
088f68b373