fix(blockrun): surface Surf endpoint discovery so the agent stops guessing

[KillerQueen-Z]

Problem

A user hit this cascade (real report):

✗ BlockRun GET /v1/surf/market/concept-ranking failed: Not Found (404)
✗ BlockRun GET /v1/surf/market/token-ranking  failed: Not Found (404)
✗ BlockRun GET /openapi.json — path must start with "/v1/" or "/.well-known/"
✗ BlockRun has failed 3 times this session and is now disabled.

Reproduced locally: the agent guessed non-existent Surf paths, tried to self-correct via /openapi.json (which 404s through this tool), and tripped the tool-failure circuit breaker.

Root cause (two issues, neither is "the LLM being dumb")

1. The prompt invited guessing. Surf was advertised as wildcards (/v1/surf/market/*) + prose ("token rankings"), with no exact paths inline. The model completed the prose into a plausible-but-wrong path (market/token-ranking). The exact list lives in a skill doc that isn't reliably loaded, and /openapi.json only covers 17 of 83 surf endpoints and is unreachable through this tool (it prepends /api, and the openapi rewrite is site-root).

2. The gateway already returned the answer — the tool hid it. A wrong /v1/surf/... path returns a 404 whose body lists every valid endpoint under available (all 83, straight from the live registry). But the tool put that in fullOutput and only showed the model "Not Found", so the agent never saw it.

Fix (prevention + cure)

• Inline high-frequency Surf endpoints with exact paths (market/ranking, fear-greed, price, etf, options, exchange/*, liquidations, indicators) + an explicit guard: "there is no market/token-ranking or market/concept-ranking".
• Discovery note: tell the model a wrong /v1/surf/ path returns available — read it and retry instead of looping.
• Surface available + message into the model-visible output on any 4xx (blockrun.ts). Comes straight from the live registry, so it's complete and never drifts. Guarded with Array.isArray so non-Surf 4xx bodies are unaffected.

Regression

Same repro prompt, after the fix:

> Use the BlockRun surf API to get the current crypto market token rankings...
→ agent calls /v1/surf/market/ranking on the FIRST try
→ returns top-20 table with prices / 24h change / market cap
→ no 404s, no circuit breaker

(Tested with a forced model since the router's default pick nvidia/deepseek-v4-flash was provider-side 503 at the time — unrelated infra.)

Known limitation / follow-up

The inlined list in context.ts is hand-written, so it can drift from the gateway's surf.ts registry over time. The durable fix is a generated typed Surf tool whose endpoint enum is derived from SURF_ENDPOINTS (or /openapi.json) — tracked as a follow-up. This PR is the immediate, low-risk stop-gap; the 404-surfacing cure already covers all 83 endpoints regardless of what's inlined.

Scope

Two files (src/tools/blockrun.ts, src/agent/context.ts), +18/-7. No behavior change for non-Surf endpoints. npm run build clean.