chore: initial commit of Go API gateway

Baseline for the Kong replacement on api.riotpiao.com. Brings the working tree under version control for the first time: gateway source, the task board that drives the agent runs, test fixtures, and K8s manifests. Anchor the gateway ignore rule to the repo root. Unanchored, "gateway" also matched the cmd/gateway/ source directory, so the program entrypoint was excluded from every commit. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
2026-08-19 20:54:34 -07:00
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+# 2.13 — Anthropic error shape on `/llm/*` (RED)
+
+Phase: 2 — LLM surfaces
+Stage: RED
+Depends on: [2.10](2.10-anthropic-request-translation.md), [4.3](4.3-problem-json-errors.md)
+
+`/v1/*` renders rejections as RFC 9457 `application/problem+json`. `/llm/*` must not.
+The same underlying rejection gets two renderings, chosen purely by which surface
+received the request. Write the failing tests against both renderings first.
+
+- [ ] Every error response from a `/llm/*` path has the body
+      `{"type":"error","error":{"type":"...","message":"..."}}` and
+      `Content-Type: application/json`
+- [ ] No `/llm/*` response ever carries `application/problem+json`, and no `/v1/*`
+      response ever carries the Anthropic error shape
+- [ ] An unknown or missing `model` returns `invalid_request_error` with a message
+      naming the rejected value and listing the configured model names, derived from
+      the registry rather than hardcoded
+- [ ] A request missing the required `max_tokens` returns `invalid_request_error`
+      naming `max_tokens`
+- [ ] A body that is not valid JSON returns `invalid_request_error` with a message
+      distinguishable from the unknown-model case
+- [ ] A request for an out-of-scope feature returns `invalid_request_error` naming the
+      feature, for example tools, images or prompt caching
+- [ ] Exhausting the shared slot queue returns HTTP 429 with error type
+      `rate_limit_error` and a `Retry-After` header
+- [ ] An upstream failure or timeout returns HTTP 5xx with error type `api_error`, and
+      the message leaks no upstream host, port or internal path
+- [ ] No rejection reaches an upstream, and none falls back to a default model
+- [ ] Each rejection is logged with its reason and its surface; the request body is
+      never logged
+- [ ] The same malformed request sent to `/v1/chat/completions` and `/llm/v1/messages`
+      yields the same HTTP status with the two different body shapes
+
+## Verify
+
+```bash
+curl -s -i localhost:8080/llm/v1/messages -H 'content-type: application/json' \
+  -d '{"model":"gpt-4","max_tokens":8,"messages":[]}'
+# expected: 4xx, content-type application/json, body {"type":"error","error":{"type":"invalid_request_error",...}}
+#           listing reasoning, ornith:35b, qwen2.5:3b-instruct
+
+curl -s -i localhost:8080/llm/v1/messages -H 'content-type: application/json' -d 'not json' \
+  | grep -i 'content-type'
+# expected: application/json, never application/problem+json
+
+curl -s -i localhost:8080/v1/chat/completions -H 'content-type: application/json' \
+  -d '{"model":"gpt-4","messages":[]}' | grep -i 'content-type'
+# expected: application/problem+json, confirming the two surfaces render differently
+```