Vibecode MailerLite
track this build5 phases, 16 steps, beginner friendly0%KINDA · weekend project
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.
the project pack5 files · written for this build, step by step
You are building a lean indie version of MailerLite. Create the following project files first, then implement the application by following them. Keep the files updated as decisions change. Do not collapse this into a single README or prompt. ===== README.md ===== # MailerLite · indie build Build a signup landing page with groups and a modest welcome campaign. Estimated effort: **multi-day**. Work `BUILD_PLAN.md` top to bottom · every phase ends in a check that has to pass before the next one starts. ## Stack | Part | Choice | Why | | --- | --- | --- | | Runtime | Python 3.12+ and Flask | A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. | | Storage | SQLite through Python sqlite3 | Local ownership with explicit transactions and a portable backup path. | | Interface | Jinja HTML templates, CSS and vanilla JavaScript | Implement the specified screens directly with labelled controls and progressive enhancement. | | Verification | Python unittest and browser acceptance fixtures | Check invariants and the actual user workflow before the next phase. | ## Before you start Have every one of these ready. The plan assumes them from step one. - [ ] **Python 3.12 or newer and a terminal** · Python is free; this local prototype requires no hosting subscription. - Why: The local backend, tests and storage use Python. - Get it: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. - Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. - [ ] **A current desktop browser and text editor** · No paid service required for this local step. - Why: You need to view the local interface and edit generated project files. - Get it: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. - Verify: You can create a text file in the project folder and open browser developer tools. - [ ] **MailerLite acceptance sample** · No paid service required for this local step. - Why: This fixture makes the first end-to-end check reproducible. - Get it: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. - Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. - [ ] **Confirm the bounded replacement** · No paid service required for this local step. - Why: The full commercial product is larger than this guide. - Get it: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. - Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. - [ ] **An SMTP relay and one verified test recipient** · Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Why: Outbound confirmations or replies need a delivery provider; a fake adapter covers automated tests. - Get it: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. - Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. ## Quick start ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` Then copy `.env.example` to `.env` and fill in the values it documents. ## Honest limits This build deliberately does not replace: - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks If one of those is essential to you, that is the reason to keep paying for MailerLite, and the README should say so rather than pretend. ===== BRIEF.md ===== # Build brief · MailerLite The one-shot brief this plan expands. `BUILD_PLAN.md` (or `MILESTONES.md`) is the same sequence broken into steps and checks; where the two disagree, the plan wins. Build me a signup landing page with groups and a modest welcome campaign as a bounded replacement for MailerLite. Build it in phases in the order below. Do not write the whole product in one pass. Finish the current phase, run its Done when checks, fix failures, then continue. Indie mode completes Phases 1-5. Phase 6 is required before shared or public deployment. ### Stack (fixed, do not substitute) - Runtime: Python 3.12+ and Flask. A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. - Storage: SQLite through Python sqlite3. Local ownership with explicit transactions and a portable backup path. - Interface: Jinja HTML templates, CSS and vanilla JavaScript. Implement the specified screens directly with labelled controls and progressive enhancement. - Verification: Python unittest and browser acceptance fixtures. Check invariants and the actual user workflow before the next phase. ### Data model (create this before Phase 1) - pages(id,slug,title,body,group_id,published) - subscribers(id,email,state,confirmed_at) - groups(id,name) - memberships(subscriber_id,group_id) - welcomes(id,group_id,subject,body) - deliveries(id,subscriber_id,welcome_id,state) - Use stable ids and explicit relationships; add auxiliary tables named by the phases before those phases use them. - Acceptance fixture: Two landing pages for different groups and one email signing up on both. ### Prerequisites and configuration - Python 3.12 or newer and a terminal: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. Cost: Python is free; this local prototype requires no hosting subscription. - A current desktop browser and text editor: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. Verify: You can create a text file in the project folder and open browser developer tools. Cost: No paid service required for this local step. - MailerLite acceptance sample: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. Cost: No paid service required for this local step. - Confirm the bounded replacement: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. Cost: No paid service required for this local step. - An SMTP relay and one verified test recipient: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. Cost: Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Configuration: DATA_DIR, SECRET_KEY, APP_MODE, SITE_URL, SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, MAIL_FROM, MAIL_TEST_TO. Ship .env.example, replace placeholders and exclude secrets from git. ### Phase 1 · Local foundation and data contract Build: Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. - Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Commands, after creating the named files: `python -m venv .venv`; `python -m pip install Flask Flask-WTF python-dotenv waitress tzdata`; `python -m pip freeze > requirements.txt`; `python -m flask --app app run --host 127.0.0.1`. - For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Commands, after creating the named files: `python manage.py init`; `python manage.py seed`. - Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. - Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Commands, after creating the named files: `python scripts/smtp_probe.py`. - Trap: The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. Done when: The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. Restarting preserves the seeded records or canonical files; running init again deletes nothing. A cross-origin state-changing request to an admin route is refused. Do not build yet: Do not start landing form and confirmation until these checks pass. ### Phase 2 · Landing form and confirmation Build: Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. - Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: A confirmation link should confirm only the intended signup and group. Done when: An unconfirmed signup never enters the send queue. Submitting the same email twice does not create a second subscriber. Do not build yet: Do not start group welcome until these checks pass. ### Phase 3 · Group welcome Build: Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. - Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Groups and computed segments have different meanings; keep this v1 group-based. Done when: The reader confirmed for both groups gets at most one copy of each distinct welcome. An unsubscribe blocks future welcomes across all groups. Do not build yet: Do not start manage and recover until these checks pass. ### Phase 4 · Manage and recover Build: Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. - Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. Done when: Importing an old backup cannot automatically unsuppress an address in the current database. A timeout after SMTP transmission creates unknown rather than a duplicate retry. Do not build yet: Do not start portable delivery and clean-start proof until these checks pass. ### Phase 5 · Portable delivery and clean-start proof Build: Finish the MailerLite replacement with a documented first-run path and a recoverable export. - Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. - Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. - Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Commands, after creating the named files: `python -m pip install -r requirements.txt`; `python -m unittest discover -s test`. - Trap: Export without an import or restore rehearsal is not verified portability. Done when: A new folder reaches the documented fixture outcome using only README instructions. A backup restored in isolation preserves the proof data and can be opened. Do not build yet: Do not start operate and share with access controls until these checks pass. ### Phase 6 · Operate and share with access controls (product-builder only) Build: Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. - Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. - Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Commands, after creating the named files: `waitress-serve --listen=127.0.0.1:5000 app:app`. - Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. - Trap: Product mode is additional engineering, not a switch that makes a local prototype production-ready. Done when: An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. Do not build yet: Do not add new providers or vendor-scale features until the release gates are recorded. ### Out of scope (and why) - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations: retain the paid product if this capability is essential; it is outside this bounded build. - inbox-placement expertise: retain the paid product if this capability is essential; it is outside this bounded build. - advanced automations: retain the paid product if this capability is essential; it is outside this bounded build. - commerce integrations: retain the paid product if this capability is essential; it is outside this bounded build. - recommendation and ad networks: retain the paid product if this capability is essential; it is outside this bounded build. ### README must contain - Exact install, configure, initialize, start, test and recovery commands for a clean folder. - The schema, fixture, acceptance results, private data locations and export format. - Every prerequisite and secret source, actual running costs and deliberately excluded capabilities. - An honest distinction between tests actually run and checks still awaiting real credentials or deployment. - Dependency documentation reviewed 2026-09-05: https://flask.palletsprojects.com/en/stable/installation/ ; https://docs.python.org/3/library/sqlite3.html ; https://flask-wtf.readthedocs.io/en/1.2.x/csrf/ ; https://docs.pylonsproject.org/projects/waitress/en/stable/usage.html ; https://docs.python.org/3/library/smtplib.html. Recheck before upgrading; freeze the versions actually tested. ===== AGENTS.md ===== # Agent instructions · MailerLite indie build - Read `README.md` and `BUILD_PLAN.md` before writing code. The stack is fixed: Python 3.12+ and Flask, SQLite through Python sqlite3, Jinja HTML templates, CSS and vanilla JavaScript, Python unittest and browser acceptance fixtures. Do not substitute. - Work one phase at a time, in order. Do not start a phase until every "Done when" item of the previous one passes. - Prefer the fewest moving parts that satisfy the step. No frameworks, services or dependencies the plan does not name. - Secrets live in `.env`, never in source or logs. Keep `.env.example` current when a variable is introduced. - Do not invent cryptography, security guarantees, APIs or compliance claims. - Add a focused test for every destructive, security-sensitive or data-loss path the plan names. - Run the project checks before declaring a phase complete, and record any deliberate shortcut in the README under "Tradeoffs". ## Known traps - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. - A confirmation link should confirm only the intended signup and group. - Groups and computed segments have different meanings; keep this v1 group-based. - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - Export without an import or restore rehearsal is not verified portability. ===== BUILD_PLAN.md ===== # Build plan · MailerLite Build a signup landing page with groups and a modest welcome campaign. Phases are in dependency order. Each ends in a "Done when" list; treat an unticked item as a blocker, not a note. ## Phase 1 · Local foundation and data contract Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. ### Steps 1. Create and start the local application Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Files: `app.py`, `requirements.txt`, `.env.example`, `.gitignore` ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` 2. Implement storage and seed the named fixture For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Files: `schema.sql`, `db.py`, `manage.py`, `fixtures/README.md` ```sh python manage.py init python manage.py seed ``` 3. Protect the local request boundary Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. Files: `app.py`, `templates/base.html`, `test/test_foundation.py` 4. Implement and test the email adapter Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Files: `providers/mail.py`, `scripts/smtp_probe.py` ```sh python scripts/smtp_probe.py ``` ### Done when - [ ] The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. - [ ] Restarting preserves the seeded records or canonical files; running init again deletes nothing. - [ ] A cross-origin state-changing request to an admin route is refused. ### Watch out - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. ## Phase 2 · Landing form and confirmation Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. ### Steps 1. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Files: `features/landing_form_and_confirmation.py`, `templates/landing_form_and_confirmation.html` 2. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Files: `features/landing_form_and_confirmation.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_landing_form_and_confirmation.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] An unconfirmed signup never enters the send queue. - [ ] Submitting the same email twice does not create a second subscriber. ### Watch out - A confirmation link should confirm only the intended signup and group. ## Phase 3 · Group welcome Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. ### Steps 1. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Files: `features/group_welcome.py`, `templates/group_welcome.html` 2. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Files: `features/group_welcome.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_group_welcome.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] An unsubscribe blocks future welcomes across all groups. ### Watch out - Groups and computed segments have different meanings; keep this v1 group-based. ## Phase 4 · Manage and recover Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. ### Steps 1. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Files: `features/manage_and_recover.py`, `templates/manage_and_recover.html` 2. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Files: `features/manage_and_recover.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_manage_and_recover.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A timeout after SMTP transmission creates unknown rather than a duplicate retry. ### Watch out - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. ## Phase 5 · Portable delivery and clean-start proof Finish the MailerLite replacement with a documented first-run path and a recoverable export. ### Steps 1. Write the user-facing runbook Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. Files: `README.md`, `.env.example` 2. Create and rehearse a recoverable backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Files: `OPERATIONS.md`, `scripts/backup.py` 3. Reproduce the first-run experience Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Files: `README.md`, `verification.md` ```sh python -m pip install -r requirements.txt python -m unittest discover -s test ``` ### Done when - [ ] A new folder reaches the documented fixture outcome using only README instructions. - [ ] A backup restored in isolation preserves the proof data and can be opened. ### Watch out - Export without an import or restore rehearsal is not verified portability. ## Not in this build - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks ## After v1, if you want it - Extend manage and recover only after the fixture and recovery checks pass. - Before adding another integration, document its credentials, limits, cost and failure behavior with primary-source links. ===== .env.example ===== # Copy to .env and fill in. Never commit .env; this file documents it. # Required. A new private folder this application creates on first run; never serve it as static files. DATA_DIR=./data/mailerlite # Required · secret. Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. SECRET_KEY=replace-with-a-random-secret # Required. Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. APP_MODE=indie # Required. The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. SITE_URL=http://127.0.0.1:5000 # Required. Copy the SMTP hostname from the relay dashboard. SMTP_HOST=replace-with-relay-host # Required. Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. SMTP_PORT=587 # Required · secret. Copy the relay username; it may differ from your sign-in email. SMTP_USER=replace-with-smtp-user # Required · secret. Create SMTP credentials in the relay dashboard, not your personal mailbox password. SMTP_PASSWORD=replace-with-smtp-password # Required. Your relay-verified sender address; replace before real sends. MAIL_FROM=owner@example.com # Required. An inbox you control for the explicit preflight test. MAIL_TEST_TO=owner@example.com
You are building a lean indie version of MailerLite. Create the following project files first, then implement the application by following them. Keep the files updated as decisions change. Do not collapse this into a single README or prompt. ===== README.md ===== # MailerLite · indie build Build a signup landing page with groups and a modest welcome campaign. Estimated effort: **multi-day**. Work `BUILD_PLAN.md` top to bottom · every phase ends in a check that has to pass before the next one starts. ## Stack | Part | Choice | Why | | --- | --- | --- | | Runtime | Python 3.12+ and Flask | A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. | | Storage | SQLite through Python sqlite3 | Local ownership with explicit transactions and a portable backup path. | | Interface | Jinja HTML templates, CSS and vanilla JavaScript | Implement the specified screens directly with labelled controls and progressive enhancement. | | Verification | Python unittest and browser acceptance fixtures | Check invariants and the actual user workflow before the next phase. | ## Before you start Have every one of these ready. The plan assumes them from step one. - [ ] **Python 3.12 or newer and a terminal** · Python is free; this local prototype requires no hosting subscription. - Why: The local backend, tests and storage use Python. - Get it: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. - Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. - [ ] **A current desktop browser and text editor** · No paid service required for this local step. - Why: You need to view the local interface and edit generated project files. - Get it: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. - Verify: You can create a text file in the project folder and open browser developer tools. - [ ] **MailerLite acceptance sample** · No paid service required for this local step. - Why: This fixture makes the first end-to-end check reproducible. - Get it: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. - Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. - [ ] **Confirm the bounded replacement** · No paid service required for this local step. - Why: The full commercial product is larger than this guide. - Get it: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. - Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. - [ ] **An SMTP relay and one verified test recipient** · Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Why: Outbound confirmations or replies need a delivery provider; a fake adapter covers automated tests. - Get it: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. - Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. ## Quick start ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` Then copy `.env.example` to `.env` and fill in the values it documents. ## Honest limits This build deliberately does not replace: - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks If one of those is essential to you, that is the reason to keep paying for MailerLite, and the README should say so rather than pretend. ===== BRIEF.md ===== # Build brief · MailerLite The one-shot brief this plan expands. `BUILD_PLAN.md` (or `MILESTONES.md`) is the same sequence broken into steps and checks; where the two disagree, the plan wins. Build me a signup landing page with groups and a modest welcome campaign as a bounded replacement for MailerLite. Build it in phases in the order below. Do not write the whole product in one pass. Finish the current phase, run its Done when checks, fix failures, then continue. Indie mode completes Phases 1-5. Phase 6 is required before shared or public deployment. ### Stack (fixed, do not substitute) - Runtime: Python 3.12+ and Flask. A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. - Storage: SQLite through Python sqlite3. Local ownership with explicit transactions and a portable backup path. - Interface: Jinja HTML templates, CSS and vanilla JavaScript. Implement the specified screens directly with labelled controls and progressive enhancement. - Verification: Python unittest and browser acceptance fixtures. Check invariants and the actual user workflow before the next phase. ### Data model (create this before Phase 1) - pages(id,slug,title,body,group_id,published) - subscribers(id,email,state,confirmed_at) - groups(id,name) - memberships(subscriber_id,group_id) - welcomes(id,group_id,subject,body) - deliveries(id,subscriber_id,welcome_id,state) - Use stable ids and explicit relationships; add auxiliary tables named by the phases before those phases use them. - Acceptance fixture: Two landing pages for different groups and one email signing up on both. ### Prerequisites and configuration - Python 3.12 or newer and a terminal: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. Cost: Python is free; this local prototype requires no hosting subscription. - A current desktop browser and text editor: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. Verify: You can create a text file in the project folder and open browser developer tools. Cost: No paid service required for this local step. - MailerLite acceptance sample: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. Cost: No paid service required for this local step. - Confirm the bounded replacement: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. Cost: No paid service required for this local step. - An SMTP relay and one verified test recipient: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. Cost: Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Configuration: DATA_DIR, SECRET_KEY, APP_MODE, SITE_URL, SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, MAIL_FROM, MAIL_TEST_TO. Ship .env.example, replace placeholders and exclude secrets from git. ### Phase 1 · Local foundation and data contract Build: Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. - Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Commands, after creating the named files: `python -m venv .venv`; `python -m pip install Flask Flask-WTF python-dotenv waitress tzdata`; `python -m pip freeze > requirements.txt`; `python -m flask --app app run --host 127.0.0.1`. - For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Commands, after creating the named files: `python manage.py init`; `python manage.py seed`. - Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. - Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Commands, after creating the named files: `python scripts/smtp_probe.py`. - Trap: The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. Done when: The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. Restarting preserves the seeded records or canonical files; running init again deletes nothing. A cross-origin state-changing request to an admin route is refused. Do not build yet: Do not start landing form and confirmation until these checks pass. ### Phase 2 · Landing form and confirmation Build: Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. - Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: A confirmation link should confirm only the intended signup and group. Done when: An unconfirmed signup never enters the send queue. Submitting the same email twice does not create a second subscriber. Do not build yet: Do not start group welcome until these checks pass. ### Phase 3 · Group welcome Build: Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. - Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Groups and computed segments have different meanings; keep this v1 group-based. Done when: The reader confirmed for both groups gets at most one copy of each distinct welcome. An unsubscribe blocks future welcomes across all groups. Do not build yet: Do not start manage and recover until these checks pass. ### Phase 4 · Manage and recover Build: Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. - Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. Done when: Importing an old backup cannot automatically unsuppress an address in the current database. A timeout after SMTP transmission creates unknown rather than a duplicate retry. Do not build yet: Do not start portable delivery and clean-start proof until these checks pass. ### Phase 5 · Portable delivery and clean-start proof Build: Finish the MailerLite replacement with a documented first-run path and a recoverable export. - Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. - Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. - Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Commands, after creating the named files: `python -m pip install -r requirements.txt`; `python -m unittest discover -s test`. - Trap: Export without an import or restore rehearsal is not verified portability. Done when: A new folder reaches the documented fixture outcome using only README instructions. A backup restored in isolation preserves the proof data and can be opened. Do not build yet: Do not start operate and share with access controls until these checks pass. ### Phase 6 · Operate and share with access controls (product-builder only) Build: Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. - Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. - Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Commands, after creating the named files: `waitress-serve --listen=127.0.0.1:5000 app:app`. - Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. - Trap: Product mode is additional engineering, not a switch that makes a local prototype production-ready. Done when: An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. Do not build yet: Do not add new providers or vendor-scale features until the release gates are recorded. ### Out of scope (and why) - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations: retain the paid product if this capability is essential; it is outside this bounded build. - inbox-placement expertise: retain the paid product if this capability is essential; it is outside this bounded build. - advanced automations: retain the paid product if this capability is essential; it is outside this bounded build. - commerce integrations: retain the paid product if this capability is essential; it is outside this bounded build. - recommendation and ad networks: retain the paid product if this capability is essential; it is outside this bounded build. ### README must contain - Exact install, configure, initialize, start, test and recovery commands for a clean folder. - The schema, fixture, acceptance results, private data locations and export format. - Every prerequisite and secret source, actual running costs and deliberately excluded capabilities. - An honest distinction between tests actually run and checks still awaiting real credentials or deployment. - Dependency documentation reviewed 2026-09-05: https://flask.palletsprojects.com/en/stable/installation/ ; https://docs.python.org/3/library/sqlite3.html ; https://flask-wtf.readthedocs.io/en/1.2.x/csrf/ ; https://docs.pylonsproject.org/projects/waitress/en/stable/usage.html ; https://docs.python.org/3/library/smtplib.html. Recheck before upgrading; freeze the versions actually tested. ===== AGENTS.md ===== # Agent instructions · MailerLite indie build - Read `README.md` and `BUILD_PLAN.md` before writing code. The stack is fixed: Python 3.12+ and Flask, SQLite through Python sqlite3, Jinja HTML templates, CSS and vanilla JavaScript, Python unittest and browser acceptance fixtures. Do not substitute. - Work one phase at a time, in order. Do not start a phase until every "Done when" item of the previous one passes. - Prefer the fewest moving parts that satisfy the step. No frameworks, services or dependencies the plan does not name. - Secrets live in `.env`, never in source or logs. Keep `.env.example` current when a variable is introduced. - Do not invent cryptography, security guarantees, APIs or compliance claims. - Add a focused test for every destructive, security-sensitive or data-loss path the plan names. - Run the project checks before declaring a phase complete, and record any deliberate shortcut in the README under "Tradeoffs". ## Known traps - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. - A confirmation link should confirm only the intended signup and group. - Groups and computed segments have different meanings; keep this v1 group-based. - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - Export without an import or restore rehearsal is not verified portability. ===== BUILD_PLAN.md ===== # Build plan · MailerLite Build a signup landing page with groups and a modest welcome campaign. Phases are in dependency order. Each ends in a "Done when" list; treat an unticked item as a blocker, not a note. ## Phase 1 · Local foundation and data contract Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. ### Steps 1. Create and start the local application Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Files: `app.py`, `requirements.txt`, `.env.example`, `.gitignore` ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` 2. Implement storage and seed the named fixture For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Files: `schema.sql`, `db.py`, `manage.py`, `fixtures/README.md` ```sh python manage.py init python manage.py seed ``` 3. Protect the local request boundary Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. Files: `app.py`, `templates/base.html`, `test/test_foundation.py` 4. Implement and test the email adapter Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Files: `providers/mail.py`, `scripts/smtp_probe.py` ```sh python scripts/smtp_probe.py ``` ### Done when - [ ] The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. - [ ] Restarting preserves the seeded records or canonical files; running init again deletes nothing. - [ ] A cross-origin state-changing request to an admin route is refused. ### Watch out - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. ## Phase 2 · Landing form and confirmation Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. ### Steps 1. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Files: `features/landing_form_and_confirmation.py`, `templates/landing_form_and_confirmation.html` 2. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Files: `features/landing_form_and_confirmation.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_landing_form_and_confirmation.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] An unconfirmed signup never enters the send queue. - [ ] Submitting the same email twice does not create a second subscriber. ### Watch out - A confirmation link should confirm only the intended signup and group. ## Phase 3 · Group welcome Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. ### Steps 1. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Files: `features/group_welcome.py`, `templates/group_welcome.html` 2. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Files: `features/group_welcome.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_group_welcome.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] An unsubscribe blocks future welcomes across all groups. ### Watch out - Groups and computed segments have different meanings; keep this v1 group-based. ## Phase 4 · Manage and recover Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. ### Steps 1. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Files: `features/manage_and_recover.py`, `templates/manage_and_recover.html` 2. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Files: `features/manage_and_recover.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_manage_and_recover.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A timeout after SMTP transmission creates unknown rather than a duplicate retry. ### Watch out - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. ## Phase 5 · Portable delivery and clean-start proof Finish the MailerLite replacement with a documented first-run path and a recoverable export. ### Steps 1. Write the user-facing runbook Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. Files: `README.md`, `.env.example` 2. Create and rehearse a recoverable backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Files: `OPERATIONS.md`, `scripts/backup.py` 3. Reproduce the first-run experience Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Files: `README.md`, `verification.md` ```sh python -m pip install -r requirements.txt python -m unittest discover -s test ``` ### Done when - [ ] A new folder reaches the documented fixture outcome using only README instructions. - [ ] A backup restored in isolation preserves the proof data and can be opened. ### Watch out - Export without an import or restore rehearsal is not verified portability. ## Not in this build - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks ## After v1, if you want it - Extend manage and recover only after the fixture and recovery checks pass. - Before adding another integration, document its credentials, limits, cost and failure behavior with primary-source links. ===== .env.example ===== # Copy to .env and fill in. Never commit .env; this file documents it. # Required. A new private folder this application creates on first run; never serve it as static files. DATA_DIR=./data/mailerlite # Required · secret. Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. SECRET_KEY=replace-with-a-random-secret # Required. Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. APP_MODE=indie # Required. The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. SITE_URL=http://127.0.0.1:5000 # Required. Copy the SMTP hostname from the relay dashboard. SMTP_HOST=replace-with-relay-host # Required. Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. SMTP_PORT=587 # Required · secret. Copy the relay username; it may differ from your sign-in email. SMTP_USER=replace-with-smtp-user # Required · secret. Create SMTP credentials in the relay dashboard, not your personal mailbox password. SMTP_PASSWORD=replace-with-smtp-password # Required. Your relay-verified sender address; replace before real sends. MAIL_FROM=owner@example.com # Required. An inbox you control for the explicit preflight test. MAIL_TEST_TO=owner@example.com
You are building a production product version of MailerLite. Create the following project files first, then implement the application by following them. Keep the files updated as decisions change. Do not collapse this into a single README or prompt. ===== PRODUCT.md ===== # MailerLite · product brief ## Problem 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. ## Product outcome An operated version of a signup landing page with groups and a modest welcome campaign, with authorized access, restore evidence and honest scope limits. ## Target user A builder who needs a maintainable product foundation, not a one-off demo. ## Required capabilities - Amazon SES account - verified sending domain - PostgreSQL - public HTTPS deploy target - DNS access ## Explicit non-goals for v1 - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks ## Success criteria - An unconfirmed signup never enters the send queue. - The reader confirmed for both groups gets at most one copy of each distinct welcome. - Importing an old backup cannot automatically unsuppress an address in the current database. - A private-data authorization check passes using a second identity. - An off-host restore drill has a date, observed result and recovery time in OPERATIONS.md. - README names the excluded vendor capabilities and actual provider/hosting costs. ===== BRIEF.md ===== # Build brief · MailerLite The one-shot brief this plan expands. `BUILD_PLAN.md` (or `MILESTONES.md`) is the same sequence broken into steps and checks; where the two disagree, the plan wins. Build me a signup landing page with groups and a modest welcome campaign as a bounded replacement for MailerLite. Build it in phases in the order below. Do not write the whole product in one pass. Finish the current phase, run its Done when checks, fix failures, then continue. Indie mode completes Phases 1-5. Phase 6 is required before shared or public deployment. ### Stack (fixed, do not substitute) - Runtime: Python 3.12+ and Flask. A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. - Storage: SQLite through Python sqlite3. Local ownership with explicit transactions and a portable backup path. - Interface: Jinja HTML templates, CSS and vanilla JavaScript. Implement the specified screens directly with labelled controls and progressive enhancement. - Verification: Python unittest and browser acceptance fixtures. Check invariants and the actual user workflow before the next phase. ### Data model (create this before Phase 1) - pages(id,slug,title,body,group_id,published) - subscribers(id,email,state,confirmed_at) - groups(id,name) - memberships(subscriber_id,group_id) - welcomes(id,group_id,subject,body) - deliveries(id,subscriber_id,welcome_id,state) - Use stable ids and explicit relationships; add auxiliary tables named by the phases before those phases use them. - Acceptance fixture: Two landing pages for different groups and one email signing up on both. ### Prerequisites and configuration - Python 3.12 or newer and a terminal: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. Cost: Python is free; this local prototype requires no hosting subscription. - A current desktop browser and text editor: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. Verify: You can create a text file in the project folder and open browser developer tools. Cost: No paid service required for this local step. - MailerLite acceptance sample: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. Cost: No paid service required for this local step. - Confirm the bounded replacement: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. Cost: No paid service required for this local step. - An SMTP relay and one verified test recipient: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. Cost: Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Configuration: DATA_DIR, SECRET_KEY, APP_MODE, SITE_URL, SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, MAIL_FROM, MAIL_TEST_TO. Ship .env.example, replace placeholders and exclude secrets from git. ### Phase 1 · Local foundation and data contract Build: Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. - Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Commands, after creating the named files: `python -m venv .venv`; `python -m pip install Flask Flask-WTF python-dotenv waitress tzdata`; `python -m pip freeze > requirements.txt`; `python -m flask --app app run --host 127.0.0.1`. - For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Commands, after creating the named files: `python manage.py init`; `python manage.py seed`. - Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. - Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Commands, after creating the named files: `python scripts/smtp_probe.py`. - Trap: The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. Done when: The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. Restarting preserves the seeded records or canonical files; running init again deletes nothing. A cross-origin state-changing request to an admin route is refused. Do not build yet: Do not start landing form and confirmation until these checks pass. ### Phase 2 · Landing form and confirmation Build: Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. - Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: A confirmation link should confirm only the intended signup and group. Done when: An unconfirmed signup never enters the send queue. Submitting the same email twice does not create a second subscriber. Do not build yet: Do not start group welcome until these checks pass. ### Phase 3 · Group welcome Build: Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. - Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Groups and computed segments have different meanings; keep this v1 group-based. Done when: The reader confirmed for both groups gets at most one copy of each distinct welcome. An unsubscribe blocks future welcomes across all groups. Do not build yet: Do not start manage and recover until these checks pass. ### Phase 4 · Manage and recover Build: Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. - Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. Done when: Importing an old backup cannot automatically unsuppress an address in the current database. A timeout after SMTP transmission creates unknown rather than a duplicate retry. Do not build yet: Do not start portable delivery and clean-start proof until these checks pass. ### Phase 5 · Portable delivery and clean-start proof Build: Finish the MailerLite replacement with a documented first-run path and a recoverable export. - Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. - Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. - Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Commands, after creating the named files: `python -m pip install -r requirements.txt`; `python -m unittest discover -s test`. - Trap: Export without an import or restore rehearsal is not verified portability. Done when: A new folder reaches the documented fixture outcome using only README instructions. A backup restored in isolation preserves the proof data and can be opened. Do not build yet: Do not start operate and share with access controls until these checks pass. ### Phase 6 · Operate and share with access controls (product-builder only) Build: Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. - Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. - Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Commands, after creating the named files: `waitress-serve --listen=127.0.0.1:5000 app:app`. - Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. - Trap: Product mode is additional engineering, not a switch that makes a local prototype production-ready. Done when: An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. Do not build yet: Do not add new providers or vendor-scale features until the release gates are recorded. ### Out of scope (and why) - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations: retain the paid product if this capability is essential; it is outside this bounded build. - inbox-placement expertise: retain the paid product if this capability is essential; it is outside this bounded build. - advanced automations: retain the paid product if this capability is essential; it is outside this bounded build. - commerce integrations: retain the paid product if this capability is essential; it is outside this bounded build. - recommendation and ad networks: retain the paid product if this capability is essential; it is outside this bounded build. ### README must contain - Exact install, configure, initialize, start, test and recovery commands for a clean folder. - The schema, fixture, acceptance results, private data locations and export format. - Every prerequisite and secret source, actual running costs and deliberately excluded capabilities. - An honest distinction between tests actually run and checks still awaiting real credentials or deployment. - Dependency documentation reviewed 2026-09-05: https://flask.palletsprojects.com/en/stable/installation/ ; https://docs.python.org/3/library/sqlite3.html ; https://flask-wtf.readthedocs.io/en/1.2.x/csrf/ ; https://docs.pylonsproject.org/projects/waitress/en/stable/usage.html ; https://docs.python.org/3/library/smtplib.html. Recheck before upgrading; freeze the versions actually tested. ===== ARCHITECTURE.md ===== # Architecture · MailerLite ## Stack | Part | Choice | Why | | --- | --- | --- | | Runtime | Python 3.12+ and Flask | A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. | | Storage | SQLite through Python sqlite3 | Local ownership with explicit transactions and a portable backup path. | | Interface | Jinja HTML templates, CSS and vanilla JavaScript | Implement the specified screens directly with labelled controls and progressive enhancement. | | Verification | Python unittest and browser acceptance fixtures | Check invariants and the actual user workflow before the next phase. | ## Modules Each module has one owner concern and a documented way to replace it. | Module | Owns | How to replace it | | --- | --- | --- | | Data and identity | pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state) | Keep stable ids and a versioned repository interface; migrate storage behind it with a fixture round-trip. | | Landing form and confirmation | Build a small responsive landing template with a signup form, source-page id and explicit consent text. | Keep the acceptance contract: An unconfirmed signup never enters the send queue. Replace only this module after replaying its fixture; preserve ids and existing records. | | Group welcome | Allow one approved welcome message per group with text/HTML previews and a test send to the owner. | Keep the acceptance contract: The reader confirmed for both groups gets at most one copy of each distinct welcome. Replace only this module after replaying its fixture; preserve ids and existing records. | | Manage and recover | Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. | Keep the acceptance contract: Importing an old backup cannot automatically unsuppress an address in the current database. Replace only this module after replaying its fixture; preserve ids and existing records. | | Operations | Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. | Change host or backup destination only after an isolated restore and authorization check. | ## Configuration Every runtime setting is an environment variable documented in `.env.example`, validated at startup, with a safe local default wherever one exists. - `DATA_DIR` · required · A new private folder this application creates on first run; never serve it as static files. - `SECRET_KEY` · required, secret · Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. - `APP_MODE` · required · Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. - `SITE_URL` · required · The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. - `SMTP_HOST` · required · Copy the SMTP hostname from the relay dashboard. - `SMTP_PORT` · required · Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. - `SMTP_USER` · required, secret · Copy the relay username; it may differ from your sign-in email. - `SMTP_PASSWORD` · required, secret · Create SMTP credentials in the relay dashboard, not your personal mailbox password. - `MAIL_FROM` · required · Your relay-verified sender address; replace before real sends. - `MAIL_TEST_TO` · required · An inbox you control for the explicit preflight test. ## Production baseline - Security: least privilege, input validation at every boundary, secret redaction in logs, rate limits on abuse-prone paths, no invented security primitives. - Data: explicit schema and migrations, transactional writes where integrity matters, backup and restore procedures that have been exercised. - Integrations: adapters around third-party providers, idempotent webhook or job processing, bounded retries, timeouts. - Observability: structured logs with request or operation ids, an error-tracking hook, and health and readiness checks where a server exists. - Quality: unit tests for domain rules, integration tests at module boundaries, one end-to-end test of the critical path. ## Decision records For each dependency in the stack table, keep a short note: why it was chosen, its failure mode, and how it is replaced. Do not add infrastructure until a requirement in `PRODUCT.md` justifies it. ===== AGENTS.md ===== # Agent instructions · MailerLite product build - Read `PRODUCT.md` and `ARCHITECTURE.md` before changing code. The stack is fixed: Python 3.12+ and Flask, SQLite through Python sqlite3, Jinja HTML templates, CSS and vanilla JavaScript, Python unittest and browser acceptance fixtures. - Implement milestone by milestone from `MILESTONES.md`; keep each change reviewable and leave the application runnable at every commit. - Treat authentication, payments, encryption, imports, webhooks and destructive actions as high-risk boundaries when present. - Never invent cryptography or silently weaken a requirement to make a check pass. - Put every external service behind an interface with a deterministic fake for tests. - Add migrations and rollback or recovery notes for every persistent data change. - Log useful operational context without credentials, tokens, passwords or personal data. - Update documentation and run every check before completing a milestone. ## Known traps - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. - A confirmation link should confirm only the intended signup and group. - Groups and computed segments have different meanings; keep this v1 group-based. - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - Export without an import or restore rehearsal is not verified portability. - Product mode is additional engineering, not a switch that makes a local prototype production-ready. ===== MILESTONES.md ===== # Delivery milestones · MailerLite Estimated effort: **multi-day** for the indie phases; the production-only milestones add the trust and operability layer. ## M1 · Local foundation and data contract Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. ### Steps 1. Create and start the local application Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Files: `app.py`, `requirements.txt`, `.env.example`, `.gitignore` ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` 2. Implement storage and seed the named fixture For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Files: `schema.sql`, `db.py`, `manage.py`, `fixtures/README.md` ```sh python manage.py init python manage.py seed ``` 3. Protect the local request boundary Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. Files: `app.py`, `templates/base.html`, `test/test_foundation.py` 4. Implement and test the email adapter Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Files: `providers/mail.py`, `scripts/smtp_probe.py` ```sh python scripts/smtp_probe.py ``` ### Done when - [ ] The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. - [ ] Restarting preserves the seeded records or canonical files; running init again deletes nothing. - [ ] A cross-origin state-changing request to an admin route is refused. ### Watch out - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. ## M2 · Landing form and confirmation Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. ### Steps 1. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Files: `features/landing_form_and_confirmation.py`, `templates/landing_form_and_confirmation.html` 2. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Files: `features/landing_form_and_confirmation.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_landing_form_and_confirmation.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] An unconfirmed signup never enters the send queue. - [ ] Submitting the same email twice does not create a second subscriber. ### Watch out - A confirmation link should confirm only the intended signup and group. ## M3 · Group welcome Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. ### Steps 1. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Files: `features/group_welcome.py`, `templates/group_welcome.html` 2. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Files: `features/group_welcome.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_group_welcome.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] An unsubscribe blocks future welcomes across all groups. ### Watch out - Groups and computed segments have different meanings; keep this v1 group-based. ## M4 · Manage and recover Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. ### Steps 1. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Files: `features/manage_and_recover.py`, `templates/manage_and_recover.html` 2. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Files: `features/manage_and_recover.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_manage_and_recover.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A timeout after SMTP transmission creates unknown rather than a duplicate retry. ### Watch out - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. ## M5 · Portable delivery and clean-start proof Finish the MailerLite replacement with a documented first-run path and a recoverable export. ### Steps 1. Write the user-facing runbook Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. Files: `README.md`, `.env.example` 2. Create and rehearse a recoverable backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Files: `OPERATIONS.md`, `scripts/backup.py` 3. Reproduce the first-run experience Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Files: `README.md`, `verification.md` ```sh python -m pip install -r requirements.txt python -m unittest discover -s test ``` ### Done when - [ ] A new folder reaches the documented fixture outcome using only README instructions. - [ ] A backup restored in isolation preserves the proof data and can be opened. ### Watch out - Export without an import or restore rehearsal is not verified portability. ## M6 · Operate and share with access controls (production only) Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. ### Steps 1. Establish owner access before exposure Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. Files: `ARCHITECTURE.md`, `OPERATIONS.md` 2. Deploy a monitored service Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Files: `Caddyfile`, `OPERATIONS.md` ```sh waitress-serve --listen=127.0.0.1:5000 app:app ``` 3. Rehearse loss and recovery Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. Files: `OPERATIONS.md`, `release-checklist.md` ### Done when - [ ] An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. - [ ] A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. - [ ] Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. ### Watch out - Product mode is additional engineering, not a switch that makes a local prototype production-ready. ===== OPERATIONS.md ===== # Operations · MailerLite ## Backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. ## Restore Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Do a restore drill before the first real user, and write the date here when it passes. ## Monitoring Check HTTP availability, free disk, backup age and domain failures for Landing form and confirmation, Group welcome, Manage and recover. Alert without logging private payloads. ## Incident checklist Pause outbound jobs and public intake as appropriate, preserve redacted diagnostics, restore an isolated verified backup, rotate affected credentials and reconcile uncertain effects before reopening. 1. Contain the issue without destroying evidence or user data. 2. Record the timeline and affected scope. 3. Rotate exposed secrets and revoke compromised sessions or credentials. 4. Restore from a verified backup when needed. 5. Document the root cause, the remediation and the regression test. ## Release gate - [ ] An unconfirmed signup never enters the send queue. - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A private-data authorization check passes using a second identity. - [ ] An off-host restore drill has a date, observed result and recovery time in OPERATIONS.md. - [ ] README names the excluded vendor capabilities and actual provider/hosting costs. ## Launch constraint Do not market omitted MailerLite capabilities as implemented. The non-goals in `PRODUCT.md` remain user-visible limitations until they are deliberately delivered. ===== .env.example ===== # Copy to .env and fill in. Never commit .env; this file documents it. # Required. A new private folder this application creates on first run; never serve it as static files. DATA_DIR=./data/mailerlite # Required · secret. Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. SECRET_KEY=replace-with-a-random-secret # Required. Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. APP_MODE=indie # Required. The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. SITE_URL=http://127.0.0.1:5000 # Required. Copy the SMTP hostname from the relay dashboard. SMTP_HOST=replace-with-relay-host # Required. Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. SMTP_PORT=587 # Required · secret. Copy the relay username; it may differ from your sign-in email. SMTP_USER=replace-with-smtp-user # Required · secret. Create SMTP credentials in the relay dashboard, not your personal mailbox password. SMTP_PASSWORD=replace-with-smtp-password # Required. Your relay-verified sender address; replace before real sends. MAIL_FROM=owner@example.com # Required. An inbox you control for the explicit preflight test. MAIL_TEST_TO=owner@example.com
README.md
# MailerLite · indie build Build a signup landing page with groups and a modest welcome campaign. Estimated effort: **multi-day**. Work `BUILD_PLAN.md` top to bottom · every phase ends in a check that has to pass before the next one starts. ## Stack | Part | Choice | Why | | --- | --- | --- | | Runtime | Python 3.12+ and Flask | A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. | | Storage | SQLite through Python sqlite3 | Local ownership with explicit transactions and a portable backup path. | | Interface | Jinja HTML templates, CSS and vanilla JavaScript | Implement the specified screens directly with labelled controls and progressive enhancement. | | Verification | Python unittest and browser acceptance fixtures | Check invariants and the actual user workflow before the next phase. | ## Before you start Have every one of these ready. The plan assumes them from step one. - [ ] **Python 3.12 or newer and a terminal** · Python is free; this local prototype requires no hosting subscription. - Why: The local backend, tests and storage use Python. - Get it: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. - Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. - [ ] **A current desktop browser and text editor** · No paid service required for this local step. - Why: You need to view the local interface and edit generated project files. - Get it: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. - Verify: You can create a text file in the project folder and open browser developer tools. - [ ] **MailerLite acceptance sample** · No paid service required for this local step. - Why: This fixture makes the first end-to-end check reproducible. - Get it: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. - Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. - [ ] **Confirm the bounded replacement** · No paid service required for this local step. - Why: The full commercial product is larger than this guide. - Get it: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. - Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. - [ ] **An SMTP relay and one verified test recipient** · Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Why: Outbound confirmations or replies need a delivery provider; a fake adapter covers automated tests. - Get it: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. - Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. ## Quick start ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` Then copy `.env.example` to `.env` and fill in the values it documents. ## Honest limits This build deliberately does not replace: - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks If one of those is essential to you, that is the reason to keep paying for MailerLite, and the README should say so rather than pretend.
BRIEF.md
# Build brief · MailerLite The one-shot brief this plan expands. `BUILD_PLAN.md` (or `MILESTONES.md`) is the same sequence broken into steps and checks; where the two disagree, the plan wins. Build me a signup landing page with groups and a modest welcome campaign as a bounded replacement for MailerLite. Build it in phases in the order below. Do not write the whole product in one pass. Finish the current phase, run its Done when checks, fix failures, then continue. Indie mode completes Phases 1-5. Phase 6 is required before shared or public deployment. ### Stack (fixed, do not substitute) - Runtime: Python 3.12+ and Flask. A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. - Storage: SQLite through Python sqlite3. Local ownership with explicit transactions and a portable backup path. - Interface: Jinja HTML templates, CSS and vanilla JavaScript. Implement the specified screens directly with labelled controls and progressive enhancement. - Verification: Python unittest and browser acceptance fixtures. Check invariants and the actual user workflow before the next phase. ### Data model (create this before Phase 1) - pages(id,slug,title,body,group_id,published) - subscribers(id,email,state,confirmed_at) - groups(id,name) - memberships(subscriber_id,group_id) - welcomes(id,group_id,subject,body) - deliveries(id,subscriber_id,welcome_id,state) - Use stable ids and explicit relationships; add auxiliary tables named by the phases before those phases use them. - Acceptance fixture: Two landing pages for different groups and one email signing up on both. ### Prerequisites and configuration - Python 3.12 or newer and a terminal: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. Cost: Python is free; this local prototype requires no hosting subscription. - A current desktop browser and text editor: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. Verify: You can create a text file in the project folder and open browser developer tools. Cost: No paid service required for this local step. - MailerLite acceptance sample: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. Cost: No paid service required for this local step. - Confirm the bounded replacement: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. Cost: No paid service required for this local step. - An SMTP relay and one verified test recipient: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. Cost: Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Configuration: DATA_DIR, SECRET_KEY, APP_MODE, SITE_URL, SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, MAIL_FROM, MAIL_TEST_TO. Ship .env.example, replace placeholders and exclude secrets from git. ### Phase 1 · Local foundation and data contract Build: Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. - Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Commands, after creating the named files: `python -m venv .venv`; `python -m pip install Flask Flask-WTF python-dotenv waitress tzdata`; `python -m pip freeze > requirements.txt`; `python -m flask --app app run --host 127.0.0.1`. - For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Commands, after creating the named files: `python manage.py init`; `python manage.py seed`. - Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. - Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Commands, after creating the named files: `python scripts/smtp_probe.py`. - Trap: The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. Done when: The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. Restarting preserves the seeded records or canonical files; running init again deletes nothing. A cross-origin state-changing request to an admin route is refused. Do not build yet: Do not start landing form and confirmation until these checks pass. ### Phase 2 · Landing form and confirmation Build: Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. - Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: A confirmation link should confirm only the intended signup and group. Done when: An unconfirmed signup never enters the send queue. Submitting the same email twice does not create a second subscriber. Do not build yet: Do not start group welcome until these checks pass. ### Phase 3 · Group welcome Build: Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. - Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Groups and computed segments have different meanings; keep this v1 group-based. Done when: The reader confirmed for both groups gets at most one copy of each distinct welcome. An unsubscribe blocks future welcomes across all groups. Do not build yet: Do not start manage and recover until these checks pass. ### Phase 4 · Manage and recover Build: Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. - Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. Done when: Importing an old backup cannot automatically unsuppress an address in the current database. A timeout after SMTP transmission creates unknown rather than a duplicate retry. Do not build yet: Do not start portable delivery and clean-start proof until these checks pass. ### Phase 5 · Portable delivery and clean-start proof Build: Finish the MailerLite replacement with a documented first-run path and a recoverable export. - Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. - Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. - Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Commands, after creating the named files: `python -m pip install -r requirements.txt`; `python -m unittest discover -s test`. - Trap: Export without an import or restore rehearsal is not verified portability. Done when: A new folder reaches the documented fixture outcome using only README instructions. A backup restored in isolation preserves the proof data and can be opened. Do not build yet: Do not start operate and share with access controls until these checks pass. ### Phase 6 · Operate and share with access controls (product-builder only) Build: Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. - Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. - Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Commands, after creating the named files: `waitress-serve --listen=127.0.0.1:5000 app:app`. - Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. - Trap: Product mode is additional engineering, not a switch that makes a local prototype production-ready. Done when: An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. Do not build yet: Do not add new providers or vendor-scale features until the release gates are recorded. ### Out of scope (and why) - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations: retain the paid product if this capability is essential; it is outside this bounded build. - inbox-placement expertise: retain the paid product if this capability is essential; it is outside this bounded build. - advanced automations: retain the paid product if this capability is essential; it is outside this bounded build. - commerce integrations: retain the paid product if this capability is essential; it is outside this bounded build. - recommendation and ad networks: retain the paid product if this capability is essential; it is outside this bounded build. ### README must contain - Exact install, configure, initialize, start, test and recovery commands for a clean folder. - The schema, fixture, acceptance results, private data locations and export format. - Every prerequisite and secret source, actual running costs and deliberately excluded capabilities. - An honest distinction between tests actually run and checks still awaiting real credentials or deployment. - Dependency documentation reviewed 2026-09-05: https://flask.palletsprojects.com/en/stable/installation/ ; https://docs.python.org/3/library/sqlite3.html ; https://flask-wtf.readthedocs.io/en/1.2.x/csrf/ ; https://docs.pylonsproject.org/projects/waitress/en/stable/usage.html ; https://docs.python.org/3/library/smtplib.html. Recheck before upgrading; freeze the versions actually tested.
AGENTS.md
# Agent instructions · MailerLite indie build - Read `README.md` and `BUILD_PLAN.md` before writing code. The stack is fixed: Python 3.12+ and Flask, SQLite through Python sqlite3, Jinja HTML templates, CSS and vanilla JavaScript, Python unittest and browser acceptance fixtures. Do not substitute. - Work one phase at a time, in order. Do not start a phase until every "Done when" item of the previous one passes. - Prefer the fewest moving parts that satisfy the step. No frameworks, services or dependencies the plan does not name. - Secrets live in `.env`, never in source or logs. Keep `.env.example` current when a variable is introduced. - Do not invent cryptography, security guarantees, APIs or compliance claims. - Add a focused test for every destructive, security-sensitive or data-loss path the plan names. - Run the project checks before declaring a phase complete, and record any deliberate shortcut in the README under "Tradeoffs". ## Known traps - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. - A confirmation link should confirm only the intended signup and group. - Groups and computed segments have different meanings; keep this v1 group-based. - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - Export without an import or restore rehearsal is not verified portability.
BUILD_PLAN.md
# Build plan · MailerLite Build a signup landing page with groups and a modest welcome campaign. Phases are in dependency order. Each ends in a "Done when" list; treat an unticked item as a blocker, not a note. ## Phase 1 · Local foundation and data contract Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. ### Steps 1. Create and start the local application Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Files: `app.py`, `requirements.txt`, `.env.example`, `.gitignore` ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` 2. Implement storage and seed the named fixture For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Files: `schema.sql`, `db.py`, `manage.py`, `fixtures/README.md` ```sh python manage.py init python manage.py seed ``` 3. Protect the local request boundary Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. Files: `app.py`, `templates/base.html`, `test/test_foundation.py` 4. Implement and test the email adapter Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Files: `providers/mail.py`, `scripts/smtp_probe.py` ```sh python scripts/smtp_probe.py ``` ### Done when - [ ] The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. - [ ] Restarting preserves the seeded records or canonical files; running init again deletes nothing. - [ ] A cross-origin state-changing request to an admin route is refused. ### Watch out - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. ## Phase 2 · Landing form and confirmation Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. ### Steps 1. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Files: `features/landing_form_and_confirmation.py`, `templates/landing_form_and_confirmation.html` 2. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Files: `features/landing_form_and_confirmation.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_landing_form_and_confirmation.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] An unconfirmed signup never enters the send queue. - [ ] Submitting the same email twice does not create a second subscriber. ### Watch out - A confirmation link should confirm only the intended signup and group. ## Phase 3 · Group welcome Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. ### Steps 1. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Files: `features/group_welcome.py`, `templates/group_welcome.html` 2. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Files: `features/group_welcome.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_group_welcome.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] An unsubscribe blocks future welcomes across all groups. ### Watch out - Groups and computed segments have different meanings; keep this v1 group-based. ## Phase 4 · Manage and recover Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. ### Steps 1. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Files: `features/manage_and_recover.py`, `templates/manage_and_recover.html` 2. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Files: `features/manage_and_recover.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_manage_and_recover.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A timeout after SMTP transmission creates unknown rather than a duplicate retry. ### Watch out - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. ## Phase 5 · Portable delivery and clean-start proof Finish the MailerLite replacement with a documented first-run path and a recoverable export. ### Steps 1. Write the user-facing runbook Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. Files: `README.md`, `.env.example` 2. Create and rehearse a recoverable backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Files: `OPERATIONS.md`, `scripts/backup.py` 3. Reproduce the first-run experience Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Files: `README.md`, `verification.md` ```sh python -m pip install -r requirements.txt python -m unittest discover -s test ``` ### Done when - [ ] A new folder reaches the documented fixture outcome using only README instructions. - [ ] A backup restored in isolation preserves the proof data and can be opened. ### Watch out - Export without an import or restore rehearsal is not verified portability. ## Not in this build - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks ## After v1, if you want it - Extend manage and recover only after the fixture and recovery checks pass. - Before adding another integration, document its credentials, limits, cost and failure behavior with primary-source links.
.env.example
# Copy to .env and fill in. Never commit .env; this file documents it. # Required. A new private folder this application creates on first run; never serve it as static files. DATA_DIR=./data/mailerlite # Required · secret. Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. SECRET_KEY=replace-with-a-random-secret # Required. Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. APP_MODE=indie # Required. The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. SITE_URL=http://127.0.0.1:5000 # Required. Copy the SMTP hostname from the relay dashboard. SMTP_HOST=replace-with-relay-host # Required. Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. SMTP_PORT=587 # Required · secret. Copy the relay username; it may differ from your sign-in email. SMTP_USER=replace-with-smtp-user # Required · secret. Create SMTP credentials in the relay dashboard, not your personal mailbox password. SMTP_PASSWORD=replace-with-smtp-password # Required. Your relay-verified sender address; replace before real sends. MAIL_FROM=owner@example.com # Required. An inbox you control for the explicit preflight test. MAIL_TEST_TO=owner@example.com
PRODUCT.md
# MailerLite · product brief ## Problem 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. ## Product outcome An operated version of a signup landing page with groups and a modest welcome campaign, with authorized access, restore evidence and honest scope limits. ## Target user A builder who needs a maintainable product foundation, not a one-off demo. ## Required capabilities - Amazon SES account - verified sending domain - PostgreSQL - public HTTPS deploy target - DNS access ## Explicit non-goals for v1 - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations - inbox-placement expertise - advanced automations - commerce integrations - recommendation and ad networks ## Success criteria - An unconfirmed signup never enters the send queue. - The reader confirmed for both groups gets at most one copy of each distinct welcome. - Importing an old backup cannot automatically unsuppress an address in the current database. - A private-data authorization check passes using a second identity. - An off-host restore drill has a date, observed result and recovery time in OPERATIONS.md. - README names the excluded vendor capabilities and actual provider/hosting costs.
BRIEF.md
# Build brief · MailerLite The one-shot brief this plan expands. `BUILD_PLAN.md` (or `MILESTONES.md`) is the same sequence broken into steps and checks; where the two disagree, the plan wins. Build me a signup landing page with groups and a modest welcome campaign as a bounded replacement for MailerLite. Build it in phases in the order below. Do not write the whole product in one pass. Finish the current phase, run its Done when checks, fix failures, then continue. Indie mode completes Phases 1-5. Phase 6 is required before shared or public deployment. ### Stack (fixed, do not substitute) - Runtime: Python 3.12+ and Flask. A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. - Storage: SQLite through Python sqlite3. Local ownership with explicit transactions and a portable backup path. - Interface: Jinja HTML templates, CSS and vanilla JavaScript. Implement the specified screens directly with labelled controls and progressive enhancement. - Verification: Python unittest and browser acceptance fixtures. Check invariants and the actual user workflow before the next phase. ### Data model (create this before Phase 1) - pages(id,slug,title,body,group_id,published) - subscribers(id,email,state,confirmed_at) - groups(id,name) - memberships(subscriber_id,group_id) - welcomes(id,group_id,subject,body) - deliveries(id,subscriber_id,welcome_id,state) - Use stable ids and explicit relationships; add auxiliary tables named by the phases before those phases use them. - Acceptance fixture: Two landing pages for different groups and one email signing up on both. ### Prerequisites and configuration - Python 3.12 or newer and a terminal: Install Python from python.org. Open a terminal in a new empty project folder. On Windows, use py -3 where this guide says python if python is not on PATH; on macOS/Linux use python3 if needed. Create .venv and activate it before installing packages. Verify: python --version reports 3.12+ and python -c "import sqlite3" succeeds. Cost: Python is free; this local prototype requires no hosting subscription. - A current desktop browser and text editor: Use an installed Chrome, Firefox or Edge browser. Open the empty project folder in your editor; open the terminal there, not in this catalog repository. Verify: You can create a text file in the project folder and open browser developer tools. Cost: No paid service required for this local step. - MailerLite acceptance sample: Create synthetic sample data before implementation: Two landing pages for different groups and one email signing up on both. Save it under fixtures/ with the expected results in fixtures/README.md; use no real credentials or customer records. Verify: The fixture files and expected outcomes exist and can be inspected without a vendor account. Cost: No paid service required for this local step. - Confirm the bounded replacement: The deliverable is a signup landing page with groups and a modest welcome campaign. Read every exclusion below. Indie mode runs locally; any public or shared use requires the product access and deployment gates first. Verify: You can name the primary workflow and the vendor features this version deliberately leaves out. Cost: No paid service required for this local step. - An SMTP relay and one verified test recipient: Obtain SMTP host, port, username and password from your chosen relay dashboard under SMTP settings. Verify the sender/domain using that provider DNS instructions. Use only your own test recipient initially and record the actual plan and rate limit in OPERATIONS.md. Verify: The supplied smtp_probe.py sends one labelled test message to your own inbox and reports the relay response without logging credentials. Cost: Provider-specific relay fees and domain costs; no free tier or delivery guarantee is assumed. - Configuration: DATA_DIR, SECRET_KEY, APP_MODE, SITE_URL, SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, MAIL_FROM, MAIL_TEST_TO. Ship .env.example, replace placeholders and exclude secrets from git. ### Phase 1 · Local foundation and data contract Build: Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. - Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Commands, after creating the named files: `python -m venv .venv`; `python -m pip install Flask Flask-WTF python-dotenv waitress tzdata`; `python -m pip freeze > requirements.txt`; `python -m flask --app app run --host 127.0.0.1`. - For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Commands, after creating the named files: `python manage.py init`; `python manage.py seed`. - Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. - Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Commands, after creating the named files: `python scripts/smtp_probe.py`. - Trap: The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. Done when: The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. Restarting preserves the seeded records or canonical files; running init again deletes nothing. A cross-origin state-changing request to an admin route is refused. Do not build yet: Do not start landing form and confirmation until these checks pass. ### Phase 2 · Landing form and confirmation Build: Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Build a small responsive landing template with a signup form, source-page id and explicit consent text. - Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. - Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: A confirmation link should confirm only the intended signup and group. Done when: An unconfirmed signup never enters the send queue. Submitting the same email twice does not create a second subscriber. Do not build yet: Do not start group welcome until these checks pass. ### Phase 3 · Group welcome Build: Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Allow one approved welcome message per group with text/HTML previews and a test send to the owner. - Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. - Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Groups and computed segments have different meanings; keep this v1 group-based. Done when: The reader confirmed for both groups gets at most one copy of each distinct welcome. An unsubscribe blocks future welcomes across all groups. Do not build yet: Do not start manage and recover until these checks pass. ### Phase 4 · Manage and recover Build: Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. - Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. - Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Commands, after creating the named files: `python -m unittest discover -s test`. - Trap: Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. Done when: Importing an old backup cannot automatically unsuppress an address in the current database. A timeout after SMTP transmission creates unknown rather than a duplicate retry. Do not build yet: Do not start portable delivery and clean-start proof until these checks pass. ### Phase 5 · Portable delivery and clean-start proof Build: Finish the MailerLite replacement with a documented first-run path and a recoverable export. - Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. - Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. - Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Commands, after creating the named files: `python -m pip install -r requirements.txt`; `python -m unittest discover -s test`. - Trap: Export without an import or restore rehearsal is not verified portability. Done when: A new folder reaches the documented fixture outcome using only README instructions. A backup restored in isolation preserves the proof data and can be opened. Do not build yet: Do not start operate and share with access controls until these checks pass. ### Phase 6 · Operate and share with access controls (product-builder only) Build: Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. - Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. - Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Commands, after creating the named files: `waitress-serve --listen=127.0.0.1:5000 app:app`. - Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. - Trap: Product mode is additional engineering, not a switch that makes a local prototype production-ready. Done when: An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. Do not build yet: Do not add new providers or vendor-scale features until the release gates are recorded. ### Out of scope (and why) - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - This is a signup landing page with groups and a modest welcome campaign; full MailerLite feature parity, vendor hosting and support are not included. - deliverability, editor polish, landing pages, automations, and integrations: retain the paid product if this capability is essential; it is outside this bounded build. - inbox-placement expertise: retain the paid product if this capability is essential; it is outside this bounded build. - advanced automations: retain the paid product if this capability is essential; it is outside this bounded build. - commerce integrations: retain the paid product if this capability is essential; it is outside this bounded build. - recommendation and ad networks: retain the paid product if this capability is essential; it is outside this bounded build. ### README must contain - Exact install, configure, initialize, start, test and recovery commands for a clean folder. - The schema, fixture, acceptance results, private data locations and export format. - Every prerequisite and secret source, actual running costs and deliberately excluded capabilities. - An honest distinction between tests actually run and checks still awaiting real credentials or deployment. - Dependency documentation reviewed 2026-09-05: https://flask.palletsprojects.com/en/stable/installation/ ; https://docs.python.org/3/library/sqlite3.html ; https://flask-wtf.readthedocs.io/en/1.2.x/csrf/ ; https://docs.pylonsproject.org/projects/waitress/en/stable/usage.html ; https://docs.python.org/3/library/smtplib.html. Recheck before upgrading; freeze the versions actually tested.
ARCHITECTURE.md
# Architecture · MailerLite ## Stack | Part | Choice | Why | | --- | --- | --- | | Runtime | Python 3.12+ and Flask | A small local HTTP application with readable server-side handlers and no JavaScript build pipeline. | | Storage | SQLite through Python sqlite3 | Local ownership with explicit transactions and a portable backup path. | | Interface | Jinja HTML templates, CSS and vanilla JavaScript | Implement the specified screens directly with labelled controls and progressive enhancement. | | Verification | Python unittest and browser acceptance fixtures | Check invariants and the actual user workflow before the next phase. | ## Modules Each module has one owner concern and a documented way to replace it. | Module | Owns | How to replace it | | --- | --- | --- | | Data and identity | pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state) | Keep stable ids and a versioned repository interface; migrate storage behind it with a fixture round-trip. | | Landing form and confirmation | Build a small responsive landing template with a signup form, source-page id and explicit consent text. | Keep the acceptance contract: An unconfirmed signup never enters the send queue. Replace only this module after replaying its fixture; preserve ids and existing records. | | Group welcome | Allow one approved welcome message per group with text/HTML previews and a test send to the owner. | Keep the acceptance contract: The reader confirmed for both groups gets at most one copy of each distinct welcome. Replace only this module after replaying its fixture; preserve ids and existing records. | | Manage and recover | Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. | Keep the acceptance contract: Importing an old backup cannot automatically unsuppress an address in the current database. Replace only this module after replaying its fixture; preserve ids and existing records. | | Operations | Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. | Change host or backup destination only after an isolated restore and authorization check. | ## Configuration Every runtime setting is an environment variable documented in `.env.example`, validated at startup, with a safe local default wherever one exists. - `DATA_DIR` · required · A new private folder this application creates on first run; never serve it as static files. - `SECRET_KEY` · required, secret · Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. - `APP_MODE` · required · Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. - `SITE_URL` · required · The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. - `SMTP_HOST` · required · Copy the SMTP hostname from the relay dashboard. - `SMTP_PORT` · required · Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. - `SMTP_USER` · required, secret · Copy the relay username; it may differ from your sign-in email. - `SMTP_PASSWORD` · required, secret · Create SMTP credentials in the relay dashboard, not your personal mailbox password. - `MAIL_FROM` · required · Your relay-verified sender address; replace before real sends. - `MAIL_TEST_TO` · required · An inbox you control for the explicit preflight test. ## Production baseline - Security: least privilege, input validation at every boundary, secret redaction in logs, rate limits on abuse-prone paths, no invented security primitives. - Data: explicit schema and migrations, transactional writes where integrity matters, backup and restore procedures that have been exercised. - Integrations: adapters around third-party providers, idempotent webhook or job processing, bounded retries, timeouts. - Observability: structured logs with request or operation ids, an error-tracking hook, and health and readiness checks where a server exists. - Quality: unit tests for domain rules, integration tests at module boundaries, one end-to-end test of the critical path. ## Decision records For each dependency in the stack table, keep a short note: why it was chosen, its failure mode, and how it is replaced. Do not add infrastructure until a requirement in `PRODUCT.md` justifies it.
AGENTS.md
# Agent instructions · MailerLite product build - Read `PRODUCT.md` and `ARCHITECTURE.md` before changing code. The stack is fixed: Python 3.12+ and Flask, SQLite through Python sqlite3, Jinja HTML templates, CSS and vanilla JavaScript, Python unittest and browser acceptance fixtures. - Implement milestone by milestone from `MILESTONES.md`; keep each change reviewable and leave the application runnable at every commit. - Treat authentication, payments, encryption, imports, webhooks and destructive actions as high-risk boundaries when present. - Never invent cryptography or silently weaken a requirement to make a check pass. - Put every external service behind an interface with a deterministic fake for tests. - Add migrations and rollback or recovery notes for every persistent data change. - Log useful operational context without credentials, tokens, passwords or personal data. - Update documentation and run every check before completing a milestone. ## Known traps - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. - A confirmation link should confirm only the intended signup and group. - Groups and computed segments have different meanings; keep this v1 group-based. - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. - Export without an import or restore rehearsal is not verified portability. - Product mode is additional engineering, not a switch that makes a local prototype production-ready.
MILESTONES.md
# Delivery milestones · MailerLite Estimated effort: **multi-day** for the indie phases; the production-only milestones add the trust and operability layer. ## M1 · Local foundation and data contract Create the runnable local foundation for a signup landing page with groups and a modest welcome campaign, including the real schema and acceptance fixture. ### Steps 1. Create and start the local application Run the venv command first, then stop and activate it before running the remaining commands. Use your OS instructions: Windows .venv\Scripts\activate.bat in cmd, or .venv\Scripts\Activate.ps1 in PowerShell; macOS/Linux source .venv/bin/activate. Then install the listed packages. Create app.py exposing app, load .env with python-dotenv, and add a /healthz route. Freeze tested dependency versions to requirements.txt. Create .env manually from .env.example; replace SECRET_KEY before launch. Files: `app.py`, `requirements.txt`, `.env.example`, `.gitignore` ```sh python -m venv .venv python -m pip install Flask Flask-WTF python-dotenv waitress tzdata python -m pip freeze > requirements.txt python -m flask --app app run --host 127.0.0.1 ``` 2. Implement storage and seed the named fixture For database-backed state create schema.sql and db.py using this model: pages(id,slug,title,body,group_id,published); subscribers(id,email,state,confirmed_at); groups(id,name); memberships(subscriber_id,group_id); welcomes(id,group_id,subject,body); deliveries(id,subscriber_id,welcome_id,state). Add the auxiliary relationships explicitly used in later phases; use stable ids, foreign keys, parameterized values and transactions. For canonical files use atomic replacement and hashes instead. Implement python manage.py init and python manage.py seed to create only synthetic data: Two landing pages for different groups and one email signing up on both. Re-running init must not erase data. Files: `schema.sql`, `db.py`, `manage.py`, `fixtures/README.md` ```sh python manage.py init python manage.py seed ``` 3. Protect the local request boundary Install Flask-WTF CSRF protection for forms and same-origin fetches, validate Host and Origin against SITE_URL, bound inputs and escape output. Deliberately public intake endpoints get bounded validation and rate limits; signed provider webhooks use signature checks instead of browser CSRF tokens. All other admin routes stay local until product authentication exists. When a later phase tests viewer/member permissions, implement the users, hashed passwords, expiring server sessions and role checks in this foundation first; product mode must never use a fabricated identity from request input. Add error, empty, keyboard-focus and retry states now. Files: `app.py`, `templates/base.html`, `test/test_foundation.py` 4. Implement and test the email adapter Create providers/mail.py using smtplib with a timeout, verified TLS/STARTTLS and an EmailMessage. Refuse placeholder credentials and non-test recipients until the owner enables sending. Implement scripts/smtp_probe.py to send one labelled message only to MAIL_TEST_TO, and provide a fake adapter for tests. Store no password or full message body in logs. Files: `providers/mail.py`, `scripts/smtp_probe.py` ```sh python scripts/smtp_probe.py ``` ### Done when - [ ] The documented start command serves /healthz and the initial screen at http://127.0.0.1:5000. - [ ] Restarting preserves the seeded records or canonical files; running init again deletes nothing. - [ ] A cross-origin state-changing request to an admin route is refused. ### Watch out - The Flask development server is for local development only. Loopback binding alone does not replace CSRF and origin validation. ## M2 · Landing form and confirmation Landing form and confirmation for MailerLite: Build a small responsive landing template with a signup form, source-page id and explicit consent text. ### Steps 1. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Build a small responsive landing template with a signup form, source-page id and explicit consent text. Files: `features/landing_form_and_confirmation.py`, `templates/landing_form_and_confirmation.html` 2. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Send expiring confirmation links and create pending group membership; use a generic response to avoid exposing existing subscriber status. Files: `features/landing_form_and_confirmation.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: An unconfirmed signup never enters the send queue. Then check: Submitting the same email twice does not create a second subscriber. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_landing_form_and_confirmation.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] An unconfirmed signup never enters the send queue. - [ ] Submitting the same email twice does not create a second subscriber. ### Watch out - A confirmation link should confirm only the intended signup and group. ## M3 · Group welcome Group welcome for MailerLite: Allow one approved welcome message per group with text/HTML previews and a test send to the owner. ### Steps 1. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Allow one approved welcome message per group with text/HTML previews and a test send to the owner. Files: `features/group_welcome.py`, `templates/group_welcome.html` 2. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Create a unique subscriber/welcome delivery after confirmation and recheck global suppression before dispatch. Files: `features/group_welcome.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: The reader confirmed for both groups gets at most one copy of each distinct welcome. Then check: An unsubscribe blocks future welcomes across all groups. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_group_welcome.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] An unsubscribe blocks future welcomes across all groups. ### Watch out - Groups and computed segments have different meanings; keep this v1 group-based. ## M4 · Manage and recover Manage and recover for MailerLite: Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. ### Steps 1. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Expose pending, confirmed and suppressed filters plus delivery accepted/failed/unknown outcomes. Files: `features/manage_and_recover.py`, `templates/manage_and_recover.html` 2. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Export subscriber, group and suppression data with ids and implement a non-reactivating import preview. Files: `features/manage_and_recover.py` 3. Exercise the acceptance fixture Use Two landing pages for different groups and one email signing up on both. Check: Importing an old backup cannot automatically unsuppress an address in the current database. Then check: A timeout after SMTP transmission creates unknown rather than a duplicate retry. Add a focused regression for the failure case under test/ using a temporary database or folder and fake external services; also perform the visible workflow in a browser. Files: `test/test_manage_and_recover.py` ```sh python -m unittest discover -s test ``` ### Done when - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A timeout after SMTP transmission creates unknown rather than a duplicate retry. ### Watch out - Advanced automation, hosted deliverability and ecommerce are outside this landing-page sender. ## M5 · Portable delivery and clean-start proof Finish the MailerLite replacement with a documented first-run path and a recoverable export. ### Steps 1. Write the user-facing runbook Document prerequisites, every configuration variable, data locations and the three domain workflows: Landing form and confirmation; Group welcome; Manage and recover. Include the exclusions, actual costs and source check date 2026-09-05. Commands shown earlier that reference project files are files the builder must implement before running them. Files: `README.md`, `.env.example` 2. Create and rehearse a recoverable backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Files: `OPERATIONS.md`, `scripts/backup.py` 3. Reproduce the first-run experience Use a new folder and only README instructions to reach the fixture outcome. Install from requirements.txt, initialize storage, run the tests and exercise the UI at 375px and 1280px; use keyboard-only controls and inspect browser errors. Record exactly what passed; do not mark unrun checks complete. Files: `README.md`, `verification.md` ```sh python -m pip install -r requirements.txt python -m unittest discover -s test ``` ### Done when - [ ] A new folder reaches the documented fixture outcome using only README instructions. - [ ] A backup restored in isolation preserves the proof data and can be opened. ### Watch out - Export without an import or restore rehearsal is not verified portability. ## M6 · Operate and share with access controls (production only) Product-builder only: make a signup landing page with groups and a modest welcome campaign operable for its stated audience before allowing remote access. ### Steps 1. Establish owner access before exposure Add owner/member/viewer authorization as appropriate, password hashes through Werkzeug, expiring server-side sessions, CSRF and login rate limits. Add users, sessions and audit schema migrations plus an owner-init command prompting securely for its password. Enforce ownership on every private read/write/download and fail closed when product setup is incomplete. Existing learner or admin identities must use this same boundary. Files: `ARCHITECTURE.md`, `OPERATIONS.md` 2. Deploy a monitored service Serve app:app with Waitress on loopback behind Caddy HTTPS. Configure trusted proxy headers narrowly, Secure/HttpOnly/SameSite cookies, upload limits, request ids and structured logs without private content. Run background jobs as a separate supervised process when the domain workflow requires them. Files: `Caddyfile`, `OPERATIONS.md` ```sh waitress-serve --listen=127.0.0.1:5000 app:app ``` 3. Rehearse loss and recovery Add a scheduled encrypted off-host backup using this procedure: Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. Monitor health, disk space, failed jobs and backup age. Stop the service to test an alert; rehearse recovery with outbound effects disabled and record recovery time. Rotate any exposed credentials and require reconciliation before resuming queues. Files: `OPERATIONS.md`, `release-checklist.md` ### Done when - [ ] An unauthenticated visitor cannot read private records, download private files or mutate the admin surface. - [ ] A viewer cannot mutate data by making a direct request, and guessed ids cannot cross ownership boundaries. - [ ] Stopping the service triggers the configured alert and the latest off-host backup restores the fixture in isolation. ### Watch out - Product mode is additional engineering, not a switch that makes a local prototype production-ready.
OPERATIONS.md
# Operations · MailerLite ## Backup Use sqlite3.Connection.backup for the database in DATA_DIR and pause writers while taking the matching attachment snapshot. Keep schema version, hashes and a manifest for mailerlite. ## Restore Restore into a separate empty directory or isolated deployment, with all outbound actions and schedules disabled. Recreate this proof: Two landing pages for different groups and one email signing up on both. Compare ids/counts and open the result before recording the restore date. Never test a restore over the only live copy. Do a restore drill before the first real user, and write the date here when it passes. ## Monitoring Check HTTP availability, free disk, backup age and domain failures for Landing form and confirmation, Group welcome, Manage and recover. Alert without logging private payloads. ## Incident checklist Pause outbound jobs and public intake as appropriate, preserve redacted diagnostics, restore an isolated verified backup, rotate affected credentials and reconcile uncertain effects before reopening. 1. Contain the issue without destroying evidence or user data. 2. Record the timeline and affected scope. 3. Rotate exposed secrets and revoke compromised sessions or credentials. 4. Restore from a verified backup when needed. 5. Document the root cause, the remediation and the regression test. ## Release gate - [ ] An unconfirmed signup never enters the send queue. - [ ] The reader confirmed for both groups gets at most one copy of each distinct welcome. - [ ] Importing an old backup cannot automatically unsuppress an address in the current database. - [ ] A private-data authorization check passes using a second identity. - [ ] An off-host restore drill has a date, observed result and recovery time in OPERATIONS.md. - [ ] README names the excluded vendor capabilities and actual provider/hosting costs. ## Launch constraint Do not market omitted MailerLite capabilities as implemented. The non-goals in `PRODUCT.md` remain user-visible limitations until they are deliberately delivered.
.env.example
# Copy to .env and fill in. Never commit .env; this file documents it. # Required. A new private folder this application creates on first run; never serve it as static files. DATA_DIR=./data/mailerlite # Required · secret. Generate with python -c "import secrets; print(secrets.token_hex(32))" and save only in .env. SECRET_KEY=replace-with-a-random-secret # Required. Use indie for loopback-only personal work. Product mode must refuse to start until owner login and the deployment gates are configured. APP_MODE=indie # Required. The origin used for local forms and links; replace with the chosen HTTPS origin in product mode. SITE_URL=http://127.0.0.1:5000 # Required. Copy the SMTP hostname from the relay dashboard. SMTP_HOST=replace-with-relay-host # Required. Use a relay supporting STARTTLS on this port; confirm it in its setup instructions. SMTP_PORT=587 # Required · secret. Copy the relay username; it may differ from your sign-in email. SMTP_USER=replace-with-smtp-user # Required · secret. Create SMTP credentials in the relay dashboard, not your personal mailbox password. SMTP_PASSWORD=replace-with-smtp-password # Required. Your relay-verified sender address; replace before real sends. MAIL_FROM=owner@example.com # Required. An inbox you control for the explicit preflight test. MAIL_TEST_TO=owner@example.com
$ choose a build depth, inspect the files, then open the complete pack in your agent
People still pay for MailerLite because newsletter operators pay for inbox placement, growth mechanics, and operational confidence on publication day. The recurring cost buys DNS authentication, reputation, bounces, complaints, unsubscribe compliance, templates, queues, analytics, backups, and support, not just the visible interface.
xdeliverability, editor polish, landing pages, automations, and integrations
xinbox-placement expertise
xadvanced automations
xcommerce integrations
xrecommendation and ad networks
share on X ↗"I just replaced MailerLite ($12/mo) with one prompt"
Don't feel like building it? These folks already made it free.
Brevo FreeCampaigns, forms and automation with a 300-email daily throttle.free↗
EmailOctopus FreeNewsletters, one form and a small welcome automation for 2,500 contacts.free↗
Kit FreeForms, landing pages and one sequence for up to 10,000 subscribers; one recommendation slot is not yours.free↗all 5 free alternatives to MailerLite →· no votes, no pay-to-list · just what's real
MailerLite pricing
| plan | monthly | annual (per mo) | what you get |
|---|---|---|---|
| free | $0/workspace | $0/workspace | 250 subscribers, 2,500 monthly emails, 2 seats, 1 website, 1 landing page, 3 forms, 3 active automations, 5 automation steps. |
| comfort | $12/workspace | $10.80/workspace | Starting paid plan; 3 seats, email sends 10x subscriber tier, 50 automations, 100 steps, 10 sites/landing pages/forms, 5 products/bookings. |
| power | $25/workspace | $22.50/workspace | Unlimited monthly emails, unlimited user seats, unlimited sites/landing pages/forms/automations, 100 automation steps, 24/7 live chat. |
| enterprise | custom | — | Custom terms above 200,000 subscribers. |
free tier$0; 250 subscribers, 2,500 monthly emails, 2 seats, 1 website, 1 landing page, 3 forms, 3 active automations, 5 automation steps.
billingmonthly + annual (-10%); subscriber-based tiers
hidden costsIf you outgrow subscriber limit, billing can move to the next tier; Free locks sending above 250 subscribers; dedicated IP add-on on higher tiers.
verified 2026-08-10 · source ↗
Vibecode MailerLite
Kinda. The core of MailerLite is buildable in a weekend with the prompt on this page, but there are real gaps: deliverability, editor polish, landing pages, automations, and integrations, inbox-placement expertise. Read the honest list above before committing.
How much does MailerLite cost?
MailerLite costs about $12/month (Comfort, checked 2026-08-10), which is $144 per year.
What do I lose by replacing MailerLite?
Honestly: deliverability, editor polish, landing pages, automations, and integrations; inbox-placement expertise; advanced automations; commerce integrations; recommendation and ad networks. If any of those are load-bearing for you, keep paying.
Is there an open-source alternative to MailerLite?
Yes: Brevo Free (Campaigns, forms and automation with a 300-email daily throttle.) EmailOctopus Free (Newsletters, one form and a small welcome automation for 2,500 contacts.) Kit Free (Forms, landing pages and one sequence for up to 10,000 subscribers; one recommendation slot is not yours.) All 5 curated free alternatives are at vibecodeit.com/mailerlite/alternatives. The prompt is for when you want it exactly your way.