[020] Slack-like Team Chat (MVP)

[iliall]

Overview

Team chat with 5 fixed users from assets/users.csv (columns: username, display_name, password). Login required; invalid credentials rejected.

Build this as a Python backend service with no UI; expose the functionality below through an HTTP API.

Features

#general Channel

• Single public channel visible to all users
• Messages returned chronologically (oldest first, newest last)

Direct Messages (DMs)

• 1:1 private conversations between any two users
• Start DM via user search (case-insensitive partial match on username or display_name, excludes self)
• One DM thread per user pair; selecting same user reopens existing conversation
• A user's DM conversations can be listed alongside #general

Messaging (both #general and DMs)

• Text messages only; whitespace-only rejected, max 2000 characters
• Messages immutable (no edit/delete)

Search

• Global search across #general and the user's own DMs (not others' private DMs)
• Case-insensitive partial text match, results newest-first
• Each result identifies the conversation it belongs to

Out of Scope

Multiple channels, group DMs, file uploads, reactions, threads, typing indicators

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Provided starting files: see 020-team-chat/assets/ — these were in the agent's working directory when it solved the task.