OpenAI Build Week

A local-first vertical slice, end to end.

Repset combines trusted Codex lifecycle hooks, an MCP server, a loopback runtime, on-device pose estimation, and a bounded GPT-5.6 selector.

The boundary flow

Codex Stopsanitized eventlocal eligibilitycurated challengeappend-only pointsMCPstatus in Codex

Codex’s role

Codex is both the product surface and the build collaborator. SessionStart initializes pseudonymous context; Stop checks a natural boundary; MCP exposes explicit status and break actions. The main Repset task remains the primary build record.

GPT-5.6’s role

GPT-5.6 receives only coarse session and preference fields and selects an ID from the reviewed catalog through strict JSON Schema. It cannot invent an exercise or infer a diagnosis. Missing credentials, timeout, refusal, malformed output, or a disallowed ID immediately uses the deterministic selector.

Technology

  • Next.jsPublic site and anonymous judge demo
  • Node 24 + SQLitePortable local runtime and append-only ledger
  • MCPExplicit Repset tools inside Codex
  • MediaPipeOn-device pose landmarks in a worker
  • Vitest + PlaywrightRules, privacy, browser, and accessibility verification

Evidence over claims

The release gate checks forbidden hook fields, loopback auth/origin controls, frame-network behavior, synthetic pose sequences, point caps, idempotency, camera denial, keyboard use, reduced motion, and a clean plugin install. Repset makes no unsupported health or credit claim.