Spin up a Vercel Sandbox, shallow-clone the bound GitHub repo, gather a spec-targeted codebase slice, and synthesize an Implementation Context via Gemini. Streams progress as NDJSON. Sole writer of intent_specs.implementation_context.

Cookie-session only — uses createClient() from @/lib/supabase/server + auth.getUser(); does NOT accept pm_live_ API keys. Role gate requires owner|admin|editor membership (treated as admin scope). Double-gated: paid plan (pro/team — free is 403) AND workspace flag implementation_context_enabled. Response is streamed NDJSON, Content-Type 'application/x-ndjson; charset=utf-8', Cache-Control no-store. Each line is a ProgressEvent { phase, message, partialResult?, updatedSpec?, error? }; errors after the 200 surface as a {phase:'error'} line, not an HTTP error. Rate limit keyed by workspace:<id>, NOT user; example products (is_example) are exempt from the cap. analyzedSpecVersion is a 16-char sha256 of canonical spec content. updatedSpec is the full mapIntentRowToApiIntent shape.