Can a prompt replace Basecamp?

Build a project workspace where email is a first-class client, not a notification channel.

Stack: your choice, Postgres, Docker Compose, a domain, and a transactional email provider with a signed inbound webhook.

Structure: a Project has exactly five sections, fixed, not configurable — Messages, To-dos, Docs & Files, Schedule, and Automatic Check-ins. Resist adding a sixth.

Messages: a threaded board. Posting notifies subscribers by email. **Replying to that email posts the reply** — parse the inbound webhook, strip the quoted history with a real quote-stripping routine rather than a naive marker search, match the thread by a token in the reply-to address, and attach any files. Test it against replies from Gmail, Outlook and Apple Mail, whose quoting conventions all differ. This is the feature the whole build turns on.

To-dos: named lists of items with an assignee and a due date. Completing one notifies whoever is subscribed to the list. No priorities, no statuses beyond done and not done, no custom fields.

Docs & Files: Markdown documents with version history, plus uploads to local disk with a content-hash filename.

Schedule: dated events, and every to-do with a due date appears here automatically.

Automatic Check-ins: a recurring question on a schedule ("What did you work on today?"), sent by email, answerable by replying, with all answers collected on one page per question per day. This is the second feature worth copying and it depends entirely on the email path working.

Subscription model: per person, per section, defaulting to on for anything you create or are assigned. One digest option that batches a day's notifications into a single email.

Guests: a role that sees only the sections marked client-visible, invited by magic link with no password. Test that a guest cannot reach a non-visible section by direct URL.

Write tests for quote stripping across the three mail clients, for reply-token matching, and for guest visibility.

Do not add custom fields, statuses, or a second project layout. The absence is the product.