MailerLite

Build the following focused alternative to MailerLite. This is a deliberately limited personal or small-team substitute, not parity with the paid service.

WORKING SLICE
Collect confirmed newsletter subscriptions through an embedded form, send a reviewed welcome sequence and publish campaign archives.

SETUP AND ARCHITECTURE
Use TypeScript, Node, PostgreSQL, a scheduled worker and one user-supplied email delivery provider. Prerequisites: A verified sending domain, a provider account, consented example recipients and its current webhook/signature documentation. Before integrating anything, record actual versions and permissions, plus model files or provider limits only where used, in the README; make unavailable dependencies visible rather than simulating success.

DOMAIN MODEL AND INVARIANTS
Store Signup, ConsentEvent, SequenceVersion, SubscriberStep and Suppression; a subscriber's sequence progress is independent of later template edits and suppression is checked at each step.

IMPLEMENTATION CONTRACT
Separate drafts, recipient snapshots, attempts and provider receipts. Honor unsubscribe and suppression at dispatch time, authenticate provider webhooks, and never replay an ambiguous send automatically. Provide an input/setup view, the main work view, and a review/export view appropriate to this workflow. Preserve the last saved state if a job or save fails. Include empty, loading, permission-denied, partial and retryable-error states. Log identifiers and error categories without secret values or unnecessary private content.

APP-SPECIFIC BOUNDARY AND RECOVERY
Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.

ACCEPTANCE SCENARIO
Unsubscribe between welcome steps, resubscribe deliberately and replay the confirmation callback; avoid duplicate subscription records or sending an old queued step. Also reopen the app after an interrupted operation, confirm the saved record/export remains inspectable, and document the recovery action. These are implementation acceptance requirements, not a claim that this guide has been tested.

DELIVERY
Deliver a runnable repository with migrations or project-format versioning, a non-sensitive example, environment/permission setup, the exact manual acceptance steps, and a backup/export-and-restore walkthrough. Implement the working slice before optional integrations; list any deferred paid-product capabilities honestly. Do not add capabilities outside the working slice just to resemble the original product.

PROJECT RULES FOR AGENTS.md
Keep the domain invariants above executable at the write boundary. Propose scope changes before adding providers or permissions. Never fabricate source evidence, publish results, identity matches or successful delivery. Preserve user originals and require an explicit confirmation for destructive changes or external publication.

# AGENTS.md — Build guide for MailerLite

## Project scope
Collect confirmed newsletter subscriptions through an embedded form, send a reviewed welcome sequence and publish campaign archives.

Catalogue verdict: kinda. The core loop is buildable, but a dependable replacement becomes a real weekend or multi-day project. For MailerLite, send newsletters, build forms, and run a small welcome sequence. The hard boundary is deliverability, editor polish, landing pages, automations, and integrations, plus deliverability, growth network, and integrations.
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
- Runtime and tools: TypeScript, Node, PostgreSQL, a scheduled worker and one user-supplied email delivery provider.
- Before starting: A verified sending domain, a provider account, consented example recipients and its current webhook/signature documentation.

## Stack and architecture
- TypeScript, Node, PostgreSQL, a scheduled worker and one user-supplied email delivery provider
- Data design: Store Signup, ConsentEvent, SequenceVersion, SubscriberStep and Suppression; a subscriber's sequence progress is independent of later template edits and suppression is checked at each step.
- Setup: A verified sending domain, a provider account, consented example recipients and its current webhook/signature documentation

## Security and data integrity
- Separate drafts, recipient snapshots, attempts and provider receipts. Honor unsubscribe and suppression at dispatch time, authenticate provider webhooks, and never replay an ambiguous send automatically.
- Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.
- Keep secrets outside client bundles and exported projects; document what leaves the device and make retention/deletion controls visible.

## Agent implementation rules
- Project rule — domain: Store Signup, ConsentEvent, SequenceVersion, SubscriberStep and Suppression; a subscriber's sequence progress is independent of later template edits and suppression is checked at each step.
- Project rule — scope and recovery: Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.
- Project rule — acceptance: Unsubscribe between welcome steps, resubscribe deliberately and replay the confirmation callback; avoid duplicate subscription records or sending an old queued step.
- Project rule — delivery: document real setup commands and permissions; do not claim a build, accuracy level, performance result or security certification that has not been demonstrated.

## Optional agent skills and references
- Recommended skill: [supabase-postgres-best-practices](https://github.com/supabase/agent-skills/blob/main/skills/supabase-postgres-best-practices/SKILL.md) — review this PostgreSQL domain schema, uniqueness constraints, transaction boundaries and access-scoped queries; Supabase hosting is not required. Follow the maintainer's installation instructions and match its requirements to the chosen runtime.
- Recommended skill: [sharp-edges](https://github.com/trailofbits/skills/blob/main/plugins/sharp-edges/skills/sharp-edges/SKILL.md) — review configuration and API defaults against the app-specific invariants and recovery boundaries above; this is not a security certification. Follow the maintainer's installation instructions and match its requirements to the chosen runtime.

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 this working slice using synthetic or explicitly authorized non-sensitive examples: Collect confirmed newsletter subscriptions through an embedded form, send a reviewed welcome sequence and publish campaign archives.
- Share a synthetic example export and the acceptance walkthrough; keep real customer, health, financial and source data private: Unsubscribe between welcome steps, resubscribe deliberately and replay the confirmation callback; avoid duplicate subscription records or sending an old queued step.
- State the limits before asking someone to replace their existing tool: Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.

## Engineering roadmap
1. Phase 1 — Pin the working slice and create its example input: Collect confirmed newsletter subscriptions through an embedded form, send a reviewed welcome sequence and publish campaign archives. Confirm setup: A verified sending domain, a provider account, consented example recipients and its current webhook/signature documentation.
2. Phase 2 — Implement persistence and write-time invariants before decorating the UI: Store Signup, ConsentEvent, SequenceVersion, SubscriberStep and Suppression; a subscriber's sequence progress is independent of later template edits and suppression is checked at each step.
3. Phase 3 — Connect the working view to real saved state. Separate drafts, recipient snapshots, attempts and provider receipts. Honor unsubscribe and suppression at dispatch time, authenticate provider webhooks, and never replay an ambiguous send automatically.
4. Phase 4 — Expose the app-specific limits and recovery path in context: Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.
5. Phase 5 — Walk through this concrete acceptance case and preserve its exported evidence: Unsubscribe between welcome steps, resubscribe deliberately and replay the confirmation callback; avoid duplicate subscription records or sending an old queued step. Finish the README and backup/restore instructions; report unfinished capabilities explicitly.

## Paid-product capabilities outside this build
- deliverability, editor polish, landing pages, automations, and integrations
- inbox-placement expertise
- advanced automations
- commerce integrations
- recommendation and ad networks

## Implementation prompt
Build the following focused alternative to MailerLite. This is a deliberately limited personal or small-team substitute, not parity with the paid service.

WORKING SLICE
Collect confirmed newsletter subscriptions through an embedded form, send a reviewed welcome sequence and publish campaign archives.

SETUP AND ARCHITECTURE
Use TypeScript, Node, PostgreSQL, a scheduled worker and one user-supplied email delivery provider. Prerequisites: A verified sending domain, a provider account, consented example recipients and its current webhook/signature documentation. Before integrating anything, record actual versions and permissions, plus model files or provider limits only where used, in the README; make unavailable dependencies visible rather than simulating success.

DOMAIN MODEL AND INVARIANTS
Store Signup, ConsentEvent, SequenceVersion, SubscriberStep and Suppression; a subscriber's sequence progress is independent of later template edits and suppression is checked at each step.

IMPLEMENTATION CONTRACT
Separate drafts, recipient snapshots, attempts and provider receipts. Honor unsubscribe and suppression at dispatch time, authenticate provider webhooks, and never replay an ambiguous send automatically. Provide an input/setup view, the main work view, and a review/export view appropriate to this workflow. Preserve the last saved state if a job or save fails. Include empty, loading, permission-denied, partial and retryable-error states. Log identifiers and error categories without secret values or unnecessary private content.

APP-SPECIFIC BOUNDARY AND RECOVERY
Use one sending provider and a small sequence. Sender reputation, spam complaints and inbox placement require ongoing operations; do not promise deliverability from a template engine.

ACCEPTANCE SCENARIO
Unsubscribe between welcome steps, resubscribe deliberately and replay the confirmation callback; avoid duplicate subscription records or sending an old queued step. Also reopen the app after an interrupted operation, confirm the saved record/export remains inspectable, and document the recovery action. These are implementation acceptance requirements, not a claim that this guide has been tested.

DELIVERY
Deliver a runnable repository with migrations or project-format versioning, a non-sensitive example, environment/permission setup, the exact manual acceptance steps, and a backup/export-and-restore walkthrough. Implement the working slice before optional integrations; list any deferred paid-product capabilities honestly. Do not add capabilities outside the working slice just to resemble the original product.

PROJECT RULES FOR AGENTS.md
Keep the domain invariants above executable at the write boundary. Propose scope changes before adding providers or permissions. Never fabricate source evidence, publish results, identity matches or successful delivery. Preserve user originals and require an explicit confirmation for destructive changes or external publication.

## 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.