Move the review agent's AI calls to the internal agents gateway and turn on agent tracing

[bryanfawcett]

The review agent in worker/ is internal tooling: it only acts on Nyuchi's own allowlisted repositories, and only Nyuchi team members can summon it. Move internal AI to the internal agents gateway (fundi), not the gateway reserved for consumer-facing Shamwari chat.

Scope:

• Route env.AI.run through fundi (AI_GATEWAY_ID), cache off, with metadata attribution (worker, job, repository, trigger kind) and no content or user identifiers.
• No gateway guardrails on this path.
• Keep the model a var so it can point at a gateway dynamic route (dynamic/review) without a code change.
• Cut waste: do not call the model at all when the commit already carries a review (webhook redelivery / re-request), instead of reviewing and then discarding the result.
• Enable Workers tracing (observability.traces.enabled = true, 100% sampling) and instrument the review turn with metadata-only agent spans (invoke_agent / chat, no prompts, diffs or responses).
• Validate (type check, tests, wrangler deploy --dry-run), merge, confirm the deploy, confirm traffic on the new gateway.

[bryanfawcett]

Hand-off — 2026-10-04

• Merged feat(worker): route reviews through the internal fundi gateway, with metadata-only tracing #24 (squash 574235b); Deploy worker workflow succeeded. Live settings confirm AI_GATEWAY_ID=fundi and Workers traces enabled.
• Gateway name: the owner renamed the internal agents gateway to fundi ("all agents carry the fundi name"); nyuchi-agents was deleted before it carried traffic. Reviews are agent runs fired by GitHub events / team mentions → fundi (not consumer shamwari, not staff chat nyuchi-ai).
• Validation: npm run build pass, npm test 161/161, wrangler deploy --dry-run pass, CI green.
• Cost: review traffic over 30 days was ~zero on every gateway, so there is no before/after to measure; spend is bounded by the mention allowlist, the 200 KB diff cap, the already-reviewed check (now before the model call) and the REVIEW_ENABLED kill switch. No daily counter (no DO/D1 in this Worker).

Left for the owner

• Publish dynamic/review on fundi (route table: mukoko-dev/mukoko-ingestion-pipeline#77), then set REVIEW_MODEL = "dynamic/review".
• The old nyuchi-github-mcp Worker (last modified 2026-09-19) is an orphan — candidate for deletion.