# AGENTS.md — Build guide for Appointlet

## Project scope
Publish one host's booking page, collect a short intake form, reserve a suitable slot, write the calendar event and send an ICS confirmation. Offer signed cancellation and rescheduling links.

Catalogue verdict: kinda. The visible booking links loop is buildable, but a credible replacement needs more than the first screen. Appointlet earns its keep through OAuth, calendar reliability, so expect a weekend or multi-day build and a narrower personal scope.
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- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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
- Google OAuth credentials, a registered HTTPS callback and calendar access granted by the owner. Confirm the provider scopes and publishing requirements before adding guests.
- 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. One Google Calendar OAuth adapter, a timezone-aware date library, and an outbox worker for email/ICS delivery.
- Scope boundary: team routing and round robin; reliable reminders and timezone edge cases

## 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.
- One Google Calendar OAuth adapter, a timezone-aware date library, and an outbox worker for email/ICS delivery.
- Domain model: meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts

## Security and data integrity
- Encrypt refresh tokens with a separately managed key; expose busy intervals rather than event titles publicly. Hash guest management tokens and bound their lifetime.
- Correctness boundary: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
- Store UTC instants plus the intended IANA timezone. Reserve locally in a transaction, recheck provider availability, create with a stable external ID, then reconcile timeouts before retrying.
- 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: meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts
- Project rule — preserve this invariant: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
- Project rule — acceptance evidence: Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking.

## Optional agent skills and references
- Optional external skill: [gws-calendar](https://github.com/googleworkspace/cli/blob/main/skills/gws-calendar/SKILL.md) — Use Google Calendar calendars, events, recurrence, free/busy queries and integration discovery through the gws CLI. 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.
- 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.

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 Appointlet-inspired workflow with owned or clearly labeled sample data: Publish one host's booking page, collect a short intake form, reserve a suitable slot, write the calendar event and send an ICS confirmation. Offer signed cancellation and rescheduling links.
- Publish a reproducible walkthrough with this observable result: Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking.
- Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: team routing and round robin; reliable reminders and timezone edge cases Avoid guaranteed savings, performance scores or implied endorsement.

## Engineering roadmap
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Publish one host's booking page, collect a short intake form, reserve a suitable slot, write the calendar event and send an ICS confirmation. Offer signed cancellation and rescheduling links. Record prerequisites, select representative user-owned fixtures and document the unsupported features: team routing and round robin; reliable reminders and timezone edge cases
2. Phase 2 — Durable model. Model meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
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. Store UTC instants plus the intended IANA timezone. Reserve locally in a transaction, recheck provider availability, create with a stable external ID, then reconcile timeouts before retrying.
4. Phase 4 — Permissions and integration failure. Encrypt refresh tokens with a separately managed key; expose busy intervals rather than event titles publicly. Hash guest management tokens and bound their lifetime. 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. Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking. 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
- team routing and round robin
- reliable reminders and timezone edge cases
- calendar-provider edge cases and timezone correctness
- multi-calendar conflict handling
- race-free booking under load

## Implementation prompt
WORKING SLICE
Publish one host's booking page, collect a short intake form, reserve a suitable slot, write the calendar event and send an ICS confirmation. Offer signed cancellation and rescheduling links.

Build this scoped Appointlet-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.
- One Google Calendar OAuth adapter, a timezone-aware date library, and an outbox worker for email/ICS delivery.

Prerequisites and limits
Google OAuth credentials, a registered HTTPS callback and calendar access granted by the owner. Confirm the provider scopes and publishing requirements before adding guests.
Outside this release: team routing and round robin; reliable reminders and timezone edge cases

Data model and correctness
meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts
Invariant: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
Store UTC instants plus the intended IANA timezone. Reserve locally in a transaction, recheck provider availability, create with a stable external ID, then reconcile timeouts before retrying.

Security and privacy
Encrypt refresh tokens with a separately managed key; expose busy intervals rather than event titles publicly. Hash guest management tokens and bound their lifetime.

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: Publish one host's booking page, collect a short intake form, reserve a suitable slot, write the calendar event and send an ICS confirmation. Offer signed cancellation and rescheduling links. Record prerequisites, select representative user-owned fixtures and document the unsupported features: team routing and round robin; reliable reminders and timezone edge cases
2. Phase 2 — Durable model. Model meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
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. Store UTC instants plus the intended IANA timezone. Reserve locally in a transaction, recheck provider availability, create with a stable external ID, then reconcile timeouts before retrying.
4. Phase 4 — Permissions and integration failure. Encrypt refresh tokens with a separately managed key; expose busy intervals rather than event titles publicly. Hash guest management tokens and bound their lifetime. 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. Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

Acceptance
Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking.
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: [gws-calendar](https://github.com/googleworkspace/cli/blob/main/skills/gws-calendar/SKILL.md) — Use Google Calendar calendars, events, recurrence, free/busy queries and integration discovery through the gws CLI. 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.
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.
Project rule — data model: meeting types, host working hours, exceptions, buffers, guest answers and booking/provider receipts
Project rule — preserve this invariant: A booking is confirmed only after the calendar event is known to exist; two guests cannot hold the same reserved interval.
Project rule — acceptance evidence: Two concurrent guests choose the same slot and only one confirms; a calendar timeout enters reconciliation, and rescheduling preserves a link to the original booking.

## 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.