# AGENTS.md — Build guide for Fillout

## Project scope
Build a branching public form that creates a row in one approved database. Validate answers locally on the server, preview field mappings and display whether each response was stored and externally synchronized.

Catalogue verdict: yes. The core loop is small enough for a capable coding agent to produce a useful local version in one sitting. For Fillout, build a polished form that writes to a user-owned database and supports simple branching. The hard boundary is excellent airtable and notion integrations, scheduling, payments, and hosted polish, plus integrations, deliverability, and workflow depth.
Use the implementation prompt below to define the deliverable. Complete each phase's acceptance checks before extending the scope.

## Working agreement
- Inspect the repository and its existing instructions before choosing paths, dependencies or commands. Keep one coherent stack and explain changes to the proposed architecture.
- Plan a vertical slice that accepts a real input and produces the useful output described below. Persist only the state the prompt calls for; respect memory-only and upstream-managed workflows. Use fixtures only when they are clearly labelled.
- After scaffolding, document the actual install, development, check and build commands in README and keep them synchronized with the package or project manifest. Do not report commands as successful unless they ran.
- Work in small steps. At handoff, list implemented flows, checks actually performed, remaining blockers, and any credentials or provider setup the owner must supply.
- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.

## Prerequisites
- A supported Node release, PostgreSQL, HTTPS for a shared deployment, and a backup destination. Begin with one workspace and explicit owner/member permissions.
- Implementation components: Next.js App Router and TypeScript for server-rendered pages and validated mutations. PostgreSQL with Drizzle migrations; Better Auth sessions for a small private workspace. A versioned JSON form schema shared by a controlled builder, public renderer and server-side validator.
- Scope boundary: excellent Airtable and Notion integrations, scheduling, payments, and hosted polish; advanced branching

## Stack and architecture
- Next.js App Router and TypeScript for server-rendered pages and validated mutations.
- PostgreSQL with Drizzle migrations; Better Auth sessions for a small private workspace.
- A versioned JSON form schema shared by a controlled builder, public renderer and server-side validator.
- Domain model: form versions, conditional steps, external row mappings, submissions and synchronization receipts

## Security and data integrity
- Authorize every record read and mutation on the server using its workspace membership; validate payloads, protect mutations against CSRF, and escape user-authored HTML. Apply per-form submission limits and spam controls; keep responses private and separate public form IDs from management permissions.
- Correctness boundary: The response is retained even if the external database is down; a retry must not create a second mapped row.
- Commit related database changes in one transaction. Use version checks for competing edits and an outbox for external notifications; retry delivery independently of saving the record.
- Export versioned JSON plus attachments and a readable CSV summary. Restore into a separate database and compare record IDs and attachment checksums before switching.

## Agent implementation rules
- Project rule — data model: form versions, conditional steps, external row mappings, submissions and synchronization receipts
- Project rule — preserve this invariant: The response is retained even if the external database is down; a retry must not create a second mapped row.
- Project rule — acceptance evidence: Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema.

## Optional agent skills and references
- Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
- Optional external skill: [vercel-composition-patterns](https://github.com/vercel-labs/agent-skills/blob/main/skills/composition-patterns/SKILL.md) — Design reusable React components with composition, context and explicit component variants. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
- Optional external skill: [supabase-postgres-best-practices](https://github.com/supabase/agent-skills/blob/main/skills/supabase-postgres-best-practices/SKILL.md) — Review PostgreSQL schemas, queries, indexes, pooling, concurrency and row-level security. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.

Read the linked SKILL.md and its dependencies before adding a skill. Select only the skills matching this project's runtime and task; their documentation does not supply API access, credentials or approval to perform external actions. Pin the reviewed revision where the tool supports it. Follow the chosen agent's documented project-level installation mechanism.

## Distribution ideas
These are optional planning notes. Obtain the owner's approval before publishing or contacting anyone.
- Demonstrate the actual Fillout-inspired workflow with owned or clearly labeled sample data: Build a branching public form that creates a row in one approved database. Validate answers locally on the server, preview field mappings and display whether each response was stored and externally synchronized.
- Publish a reproducible walkthrough with this observable result: Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema.
- Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: excellent Airtable and Notion integrations, scheduling, payments, and hosted polish; advanced branching Avoid guaranteed savings, performance scores or implied endorsement.

## Engineering roadmap
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a branching public form that creates a row in one approved database. Validate answers locally on the server, preview field mappings and display whether each response was stored and externally synchronized. Record prerequisites, select representative user-owned fixtures and document the unsupported features: excellent Airtable and Notion integrations, scheduling, payments, and hosted polish; advanced branching
2. Phase 2 — Durable model. Model form versions, conditional steps, external row mappings, submissions and synchronization receipts Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: The response is retained even if the external database is down; a retry must not create a second mapped row.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Commit related database changes in one transaction. Use version checks for competing edits and an outbox for external notifications; retry delivery independently of saving the record.
4. Phase 4 — Permissions and integration failure. Authorize every record read and mutation on the server using its workspace membership; validate payloads, protect mutations against CSRF, and escape user-authored HTML. Apply per-form submission limits and spam controls; keep responses private and separate public form IDs from management permissions. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export versioned JSON plus attachments and a readable CSV summary. Restore into a separate database and compare record IDs and attachment checksums before switching. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

## Paid-product capabilities outside this build
- excellent Airtable and Notion integrations, scheduling, payments, and hosted polish
- advanced branching
- payment and CRM integrations
- large template libraries
- enterprise compliance

## Implementation prompt
WORKING SLICE
Build a branching public form that creates a row in one approved database. Validate answers locally on the server, preview field mappings and display whether each response was stored and externally synchronized.

Build this scoped Fillout-inspired workflow with a documented data model and visible failure states.

Architecture
- Next.js App Router and TypeScript for server-rendered pages and validated mutations.
- PostgreSQL with Drizzle migrations; Better Auth sessions for a small private workspace.
- A versioned JSON form schema shared by a controlled builder, public renderer and server-side validator.

Prerequisites and limits
A supported Node release, PostgreSQL, HTTPS for a shared deployment, and a backup destination. Begin with one workspace and explicit owner/member permissions.
Outside this release: excellent Airtable and Notion integrations, scheduling, payments, and hosted polish; advanced branching

Data model and correctness
form versions, conditional steps, external row mappings, submissions and synchronization receipts
Invariant: The response is retained even if the external database is down; a retry must not create a second mapped row.
Commit related database changes in one transaction. Use version checks for competing edits and an outbox for external notifications; retry delivery independently of saving the record.

Security and privacy
Authorize every record read and mutation on the server using its workspace membership; validate payloads, protect mutations against CSRF, and escape user-authored HTML. Apply per-form submission limits and spam controls; keep responses private and separate public form IDs from management permissions.

Recovery and export
Export versioned JSON plus attachments and a readable CSV summary. Restore into a separate database and compare record IDs and attachment checksums before switching.

Implementation order
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a branching public form that creates a row in one approved database. Validate answers locally on the server, preview field mappings and display whether each response was stored and externally synchronized. Record prerequisites, select representative user-owned fixtures and document the unsupported features: excellent Airtable and Notion integrations, scheduling, payments, and hosted polish; advanced branching
2. Phase 2 — Durable model. Model form versions, conditional steps, external row mappings, submissions and synchronization receipts Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: The response is retained even if the external database is down; a retry must not create a second mapped row.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Commit related database changes in one transaction. Use version checks for competing edits and an outbox for external notifications; retry delivery independently of saving the record.
4. Phase 4 — Permissions and integration failure. Authorize every record read and mutation on the server using its workspace membership; validate payloads, protect mutations against CSRF, and escape user-authored HTML. Apply per-form submission limits and spam controls; keep responses private and separate public form IDs from management permissions. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export versioned JSON plus attachments and a readable CSV summary. Restore into a separate database and compare record IDs and attachment checksums before switching. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

Acceptance
Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema.
Use real source data or clearly labeled fixtures. Explain unsupported input and provider failures; do not fabricate analytics, delivery receipts, accuracy claims or security guarantees.

Optional agent guidance
Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: [vercel-composition-patterns](https://github.com/vercel-labs/agent-skills/blob/main/skills/composition-patterns/SKILL.md) — Design reusable React components with composition, context and explicit component variants. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: [supabase-postgres-best-practices](https://github.com/supabase/agent-skills/blob/main/skills/supabase-postgres-best-practices/SKILL.md) — Review PostgreSQL schemas, queries, indexes, pooling, concurrency and row-level security. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Project rule — data model: form versions, conditional steps, external row mappings, submissions and synchronization receipts
Project rule — preserve this invariant: The response is retained even if the external database is down; a retry must not create a second mapped row.
Project rule — acceptance evidence: Submit while the connector is unavailable, then reconnect and deliver exactly one row; changing the form leaves prior responses bound to their original schema.

## Completion evidence
Demonstrate the prompt's acceptance scenarios against the scoped workflow. Include setup from a clean checkout and failure recovery. Check persistence across restart and export/restore only for the state the prompt says to store; for memory-only tools, confirm that temporary content is discarded as specified. Record actual results and remaining limitations. A detailed plan alone does not establish a working replacement.