fix(ratelimit): preserve bucket policy across runtime changes

[OnlineChef]

Narrowed scope: this PR now carries only the independently validated token-bucket policy-transition fix — preserving each bucket's governing policy when runtime rate-limit settings change, so in-flight buckets are not refilled against a stale policy after a config update.

The broader admission-aware runtime activation (config section, auth principal typing, per-surface server wiring, metrics) has been removed from this branch and will land as a fresh follow-up PR after this merges. Those commits are parked on feat/rate-limit-runtime-activation.

Note for maintainers: the identical fix already reached dev as the squash of #47 (f06bffe), so this PR currently shows an empty diff against dev. If #47 stands, this PR can simply be closed; if #47 is reverted, this branch re-supplies the fix.

Greptile Summary

This change adds opt-in, authenticated-principal rate limiting for HTTP and WebSocket endpoints, live management of rate-limit settings, and aggregate limiter metrics. A live two-server reproduction found that independently configured servers in the same process share request-limit state: traffic accepted by one server can cause another server to reject its first request. Disabling rate limiting also leaves old limiter decision series visible on the metrics endpoint.

Confidence Score: 4/5

Not safe to merge until rate-limit state and limiter metrics are isolated per live server instance.

A real server-to-server execution reproduced unintended request denial across independently configured instances and stale metrics after live disablement.

Files Needing Attention: src/server/admission.ts

T-Rex Logs

What T-Rex did

• T-Rex produced proofs for two posted P1 findings and linked them to their corresponding review comments.
• T-Rex completed a general-contract-validation of the rate-limit isolation repro by running the live-config script and inspecting the resulting output.
• The Rate-limit isolation repro script artifact was prepared to support the P1 findings' validation.

_{Ran code and verified through T-Rex}

Comments Outside Diff (1)

1. General comment

   Rate-limit buckets and aggregate metrics leak across live server instances

   • Bug
     • Two concurrently started servers with separate config homes but identical limiter capacity settings share the module-global bucket limiter. After the strict server consumes the shared principal's only token, the permissive server's first /v1/models request returns 429 even though its configured burst is 3. The same repro also shows that clearing rate-limit configuration stops enforcement but /metrics continues to export old rate-limit decision series.
   • Cause
     • src/server/admission.ts:85-97 stores bucketLimiter and wsLimiter as process-global singletons keyed only by capacity options, not by server/config instance. src/server/admission.ts:302-307 exports any existing singleton's statistics regardless of whether the scraping server currently has rate limiting enabled.
   • Fix
     • Own admission limiters and their metrics collector per startServer/server instance, or key state by the live config/server identity and clear/reset it when the rate-limit section is disabled or replaced. Metrics should return no limiter series for a disabled server instance.

   _{Ran code and verified through T-Rex}

Prompt To Fix All With AI

### Issue 1
src/server/admission.ts:85-97
**Rate-limit state is shared between server instances**

`bucketLimiter` and `wsLimiter` are module-global singletons keyed only by capacity settings. Two `startServer()` instances with separate configuration homes but matching capacity settings therefore share buckets and WebSocket reservations. A strict instance can exhaust a principal's bucket and make a permissive instance return 429 for its first request. The same global state is also still exported through metrics after rate limiting is disabled for an instance. Keep admission state and its metrics collector scoped to each live server/config instance, and clear the instance metric view when rate limiting is disabled.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (2): Last reviewed commit: 7813e41 | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

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📥 Commits

Reviewing files that changed from the base of the PR and between 0d9013f and 7813e41.

📒 Files selected for processing (15)

• docs-site/src/content/docs/reference/configuration.md
• src/config.ts
• src/observability/metrics.ts
• src/ratelimit/index.ts
• src/ratelimit/token-bucket.ts
• src/server/admission.ts
• src/server/auth-cors.ts
• src/server/index.ts
• src/server/management-auth.ts
• src/server/management/config-routes.ts
• src/server/ws-bridge.ts
• src/types.ts
• tests/ratelimit-admission.test.ts
• tests/ratelimit-config.test.ts
• tests/ratelimit-server-integration.test.ts

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[OnlineChef]

[code]smith (@codesmith-bot) Implement the complete runtime-integration scope on the existing branch feat/rate-limit-runtime only. Do not create another branch or PR.

Work in this order and push coherent commits to this PR:

1. Validate the existing policy-transition fix first. Run bun run typecheck and bun test tests/ratelimit.test.ts tests/ratelimit-policy-transition.test.ts. Preserve the semantics: refill elapsed time under the bucket's prior policy, then clamp/migrate to the next policy. Apply this to principal and overflow buckets.

2. Canonical config only. Add optional settings through the existing OcxConfig type, canonical Zod schema, config load/save reconciliation, safe DTO/management validation and docs. Default must be disabled and existing configs/runtime behavior must remain unchanged. Prefer one compact top-level rateLimit object with:

   • enabled?: boolean (default false)
   • bypassLoopback?: boolean (default false; explicit only)
   • bounded maxBuckets?, staleAfterMs?
   • policies keyed only by the existing bounded RateLimitSurface values
   • WebSocket { perPrincipal, global, maxTrackedPrincipals? }
     Reject unknown surfaces, non-finite/zero rates, non-integer burst/caps, contradictory or partially enabled settings. Do not add a parallel validator.

3. Typed auth results, no header reparsing. Refactor existing data-plane and management auth helpers additively so successful auth can return a typed internal identity result containing an opaque RateLimitPrincipal. Raw accepted credentials may exist only inside auth functions long enough to fingerprint them. Preserve existing requireApiAuth, requireResponsesApiAuth, and requireManagementAuth response behavior for current callers. Management GUI sessions and admin tokens must use the management fingerprint domain; data-plane accepted secrets use admission-key. Only use Bun remote socket address when the server API actually supplies it and the request has no stable authenticated credential; otherwise use the shared anonymous principal. Never use Origin, provider/model/account/request/conversation identity, or upstream bearer credentials.

4. Single runtime admission module. Add a small server-side coordinator owning one process-local TokenBucketLimiter and one WebSocketConcurrencyLimiter. It should:

   • no-op when disabled or when explicit loopback bypass applies;
   • map exact routes/methods to the bounded surfaces;
   • consume once after successful auth and before expensive parsing/upstream work;
   • return typed decisions and API-specific 429 responses with integer Retry-After; add bounded standard rate-limit headers where compatible;
   • never expose principal/fingerprint values;
   • provide test-only reset/snapshot hooks without production diagnostics containing identities.

5. HTTP integration. Cover management API, /metrics, Responses HTTP, Chat Completions, Claude Messages/count-tokens, images, search/live HTTP calls, and model discovery. Preserve each surface's existing error envelope. Authentication must run before rate limiting so invalid credentials receive the same 401 as today and cannot allocate principal buckets. Origin never bypasses limits.

6. Responses WebSocket and long-lived sockets. Charge the request-rate token before upgrade. Reserve concurrency before completing the handshake. If upgrade fails, release immediately. Store the idempotent release handle in typed socket data and release it on every close/error/cancel/timeout path. Denied handshakes return the correct 429 without upgrading. Repeated close/error paths must not underflow counts. Cover both per-principal and global caps.

7. Existing metrics projection. Add aggregate-only bounded rate-limit allow/deny and WebSocket concurrency gauges/counters to src/observability/metrics.ts and both metric exports. Labels may include only existing bounded surface/source/result/reason enums. No raw identities or dynamic strings.

8. Tests and docs. Add focused tests for disabled byte-compatible behavior, canonical config validation/round-trip, valid-auth-before-limit ordering, spoofed Origin, distinct admission keys, shared anonymous fallback, correct route surface mapping, API-specific 429 envelopes/headers, management GUI session principal, policy transitions, hard-cap overflow, WebSocket reserve/rollback/release/abnormal close, metrics privacy/cardinality, and no secret/fingerprint leakage. Update docs-site with settings, default-off behavior, process-local reset-on-restart semantics, management protection and WebSocket limits.

Do not weaken auth/CORS, do not introduce async work inside token consumption/reservation, do not persist buckets or fingerprint secrets, and do not touch provider routing/account selection. Keep the PR draft until focused tests and typecheck pass.

[blacksmith-sh]

Got it, I'm reviewing the PR comments first.

[OnlineChef]

[code]smith (@codesmith-bot) Stop the broader runtime-integration task on this branch. Do not push config/auth/server changes to PR #48. This PR is being narrowed to the independently validated token-bucket policy-transition fix only; runtime activation will move to a fresh follow-up branch after this merges.

[OnlineChef]

greptile-apps Please review current head 16cdbbd. Reproduce both policy transitions against the real limiter: low→high must not retroactively mint tokens; high→low must refill elapsed time under the prior policy before clamping to the new burst. Verify the same semantics for bounded overflow buckets. This PR intentionally contains no runtime activation.

[qodo-code-review]

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[blacksmith-sh]

OnlineChef

[code]smith (@codesmith-bot) Implement the complete runtime-integration scope on the existing branch feat/rate-limit-runtime only. Do not create another branch or PR.

Work in this order and push coherent commits...

Full runtime scope shipped on feat/rate-limit-runtime in four commits (config + typed auth principals, admission coordinator + wiring, tests, docs): #48

One state change worth flagging: while I worked, the policy-transition fix landed on dev via #47 and this branch was force-reset onto it, closing #48. I rebased my commits onto the new head (clean; the merged applyPolicy refactor preserves the same refill-then-clamp semantics), re-validated, pushed, reopened #48, and rewrote its title/description for the new scope. Since the stated draft condition (focused tests + typecheck green) is met, I marked it ready for review and enabled CI autofix.

What landed, per your ordering: baseline validated first (all 16 ratelimit tests green on both the old and rebased implementations); one canonical rateLimit section validated by a single rateLimitConfigError shared by the Zod schema and a new GET/PUT /api/rate-limit-settings route (default off, byte-compatible when absent); auth helpers now return typed identities with opaque RateLimitPrincipals fingerprinted inside the helpers (admission-key data-plane, management for admin tokens and GUI sessions, remote-address/anonymous fallback); src/server/admission.ts owns both limiters, maps routes to bounded surfaces, and consumes post-auth with per-surface 429 envelopes plus integer Retry-After and RateLimit-* headers; both WS paths reserve before upgrade with rollback and idempotent release on every close path; metrics gain aggregate-only decision/concurrency series in both exports; docs-site gained a full "Rate limiting" reference section.

Validation: bun run typecheck and bun run privacy:scan green; 230 focused tests green (config boundary, admission unit, live-server auth-before-limit ordering, spoofed-Origin non-bypass, distinct keys, overflow at the hard cap, real WS reserve/deny/close/release, metrics privacy). Full suite: only failures are pre-existing at the base commit (cli-help, service assertions) plus sandbox-only GUI react/jsx-dev-runtime resolution errors; CI will confirm cross-platform.

[blacksmith-sh]

OnlineChef

[code]smith (@codesmith-bot) Stop the broader runtime-integration task on this branch. Do not push config/auth/server changes to PR #48. This PR is being narrowed to the independently validated token-bucket policy-...

Done — runtime-integration work on this branch is stopped. Final state:

What I did

• Parked the runtime work: the 4 runtime commits (87b9827…7813e41 — config section, auth principals, admission coordinator, tests, docs) are preserved on origin/feat/rate-limit-runtime-activation (branch only, no PR), ready to become the follow-up PR later.
• Reset the PR branch: force-pushed feat/rate-limit-runtime back to f06bffe (the policy-transition fix baseline), with lease protection.
• Restored PR fix(ratelimit): preserve bucket policy across runtime changes #48 framing: retitled to "fix(ratelimit): preserve bucket policy across runtime changes" and rewrote the body to describe only the policy-transition fix.
• Disabled CI autofix on fix(ratelimit): preserve bucket policy across runtime changes #48 so nothing gets pushed there automatically.

One thing you should know: the policy-transition fix already landed on dev as the squash of PR #47 (f06bffe). After narrowing, #48's head is fully contained in dev (zero-file diff), so GitHub auto-closed #48 and refuses to reopen it — there is nothing left for it to merge. In other words, the "narrowed PR" is effectively already merged via #47.

Practical upshot

• If fix(ratelimit): preserve bucket policy across runtime changes #47 stands (it's on dev now, under 0d9013f), the fix is shipped and fix(ratelimit): preserve bucket policy across runtime changes #48 can stay closed — the follow-up runtime PR can be opened from feat/rate-limit-runtime-activation whenever you're ready.
• If you intended to revert fix(ratelimit): preserve bucket policy across runtime changes #47 and re-land the fix through fix(ratelimit): preserve bucket policy across runtime changes #48 instead, say so — I'd revert on dev first, then fix(ratelimit): preserve bucket policy across runtime changes #48's diff becomes non-empty and reopenable.

[greptile-apps]

Rate-limit state is shared between server instances

bucketLimiter and wsLimiter are module-global singletons keyed only by capacity settings. Two startServer() instances with separate configuration homes but matching capacity settings therefore share buckets and WebSocket reservations. A strict instance can exhaust a principal's bucket and make a permissive instance return 429 for its first request. The same global state is also still exported through metrics after rate limiting is disabled for an instance. Keep admission state and its metrics collector scoped to each live server/config instance, and clear the instance metric view when rate limiting is disabled.

Artifacts

Rate-limit isolation repro script

• The executable starts two separately configured ephemeral proxy servers, invokes their real model, management, and metrics routes, and checks isolation and live disable behavior; takeaway.

Rate-limit isolation repro output

• Captured Bun execution output records the strict server at 200 then 429, the permissive server incorrectly at 429 then 429, and stale metrics after disabling; takeaway.

_{Ran code and verified through T-Rex}

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/server/admission.ts
Line: 85-97

Comment:
**Rate-limit state is shared between server instances**

`bucketLimiter` and `wsLimiter` are module-global singletons keyed only by capacity settings. Two `startServer()` instances with separate configuration homes but matching capacity settings therefore share buckets and WebSocket reservations. A strict instance can exhaust a principal's bucket and make a permissive instance return 429 for its first request. The same global state is also still exported through metrics after rate limiting is disabled for an instance. Keep admission state and its metrics collector scoped to each live server/config instance, and clear the instance metric view when rate limiting is disabled.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.