Fine Structure

Create a new application from a natural language prompt. The AI generates a complete web app with pages, components, styling, and data models. Returns a job_id - poll get_job_status to track progress. When the job is done, the app is ready.

Agency mode only. Create or update a client record for an account-level agent. This does not create a verified Fine Structure user account and does not transfer ownership.

Agency mode only. List client records and app handoff status for the authenticated agent.

Agency mode only. Create a new app owned by the agent, start generation, and create a claim link for the client. Ownership transfers only when the invited client logs in with the same email and accepts the claim link.

Agency mode only. Create a client claim link for an existing app owned by the agent. The client must log in with the invited email before ownership transfers.

Agency mode only. Inspect one handoff status without exposing the raw claim token.

Update an existing application with a new prompt. The AI modifies the app based on your instructions. Creates a Saved Version before the update. Returns a job_id - poll get_job_status to track progress.

Publish an app - freeze current state and make it live at a URL. Also configures whether the public URL is open, app-login gated, private, or inferred from the app.

Return a machine-readable Fine Structure / FSe2 guide for AI agents. Call this at the start of an MCP session to learn app files, entities, safe edit workflows, validation, publishing, A/B testing, secrets, and platform rules.

Return the recommended MCP tool sequence for a task type. Use this before creating apps, editing files, seeding data, publishing, setting up A/B tests, restoring versions, or configuring secrets/integrations.

Poll the status of an async generation job. Use this after create_app or update_app to know when the job is done. Returns status ('running' or 'done'), progress events, and result summary when complete.

Get app overview: files, published state, URL, active jobs.

Return editor, preview, published path, subdomain, and custom-domain links plus whether each works for anonymous visitors, app users, or Studio users based on publish and auth settings.

List an app's platform path, subdomain, and configured custom domain with verification, SSL, primary-domain, redirect, publish, and login-gating status.

Set or clear the app platform subdomain - the '<subdomain>.<base domain>' host Fine Structure already serves the app on. Runs the same ownership, format, reserved-name and uniqueness checks as the Studio subdomain field because it calls the same model function. Replacing a subdomain takes effect immediately and creates NO redirect: the previous name stops resolving to this app and is released for anyone to claim. Pass an empty subdomain to clear it. For a domain the user owns, use add_custom_dom

Check whether a platform subdomain can be claimed before calling set_app_subdomain. Returns available plus a status of available, invalid, reserved, taken, current, or empty, with the exact reason. Pass app_id (an app you own) to have that app's own current subdomain reported as 'current' instead of 'taken'.

Attach or replace the app custom domain through the same Fine Structure Studio custom-domain flow. Returns exact DNS verification and routing records for the user to configure at their DNS provider.

Return the exact DNS records and instructions required to verify and route the app custom domain.

Check Fine Structure custom-domain verification and SSL status for the configured custom domain, then save the latest status.

Set which app host should be treated as primary for generated links and custom-domain redirects.

Remove the configured custom domain from the app and clean up the platform-side hostname registration when possible.

Return SSL/certificate status and pending certificate validation DNS records for the app custom domain.

Configure custom-domain redirect policy: primary domain, optional www/root redirect, and HTTPS enforcement.

List applications owned by the authenticated user, newest activity first. Returns up to `limit` apps per call plus the total count; page with `offset` when the account has more.

Get the file tree for an app with paths and byte sizes.

Read one source file from an app's virtual filesystem. Paths follow the Fine Structure app file API, documented at https://finestructure.ai/api/mcp/docs.

Read several source files from an app's virtual filesystem. Paths follow the Fine Structure app file API, documented at https://finestructure.ai/api/mcp/docs.

Create or replace one file in an app's virtual filesystem. Creates a Saved Version before changing content. Paths and file model follow the Fine Structure app file API, documented at https://finestructure.ai/api/mcp/docs.

Patch one file by replacing exact text. Safer than full overwrite for targeted edits. Creates a Saved Version before changing content. Paths follow the Fine Structure app file API, documented at https://finestructure.ai/api/mcp/docs.

Rename or move one app source file atomically. Internally stages an upsert at new_path and a delete at old_path, validates the resulting app state, and creates a Saved Version before applying.

Deep introspection of an app: entities, pages, settings, integrations, environment variables, and file structure. Use this to understand what an app contains before updating it.

Get all entity (data model) schemas for an app, with record counts. Each entity has fields, types, and relationships.

Query app data records for one entity with optional exact-match filters.

Compatibility tool for starter-record creation. Inserts directly for the authenticated app owner; by default it only seeds an empty entity (skip_if_not_empty).

Create/insert records in one app entity. Executes directly for the authenticated app owner and returns the created record ids.

Compatibility tool that updates one record by ID. Executes directly for the authenticated app owner.

Update exact records. Select explicit record_ids or exact-match filters and provide shared changes, or provide per-record updates. Executes directly for the authenticated app owner; expected_count aborts the write on a mismatch.

Delete exact records by ID or exact-match filters. Executes directly for the authenticated app owner; pass expected_count as a safety check to abort on a mismatch.

Get all pages in an app with their file paths and sizes.

Get recent runtime errors for an app (last 20). Useful for diagnosing issues before updating.