Pinned chats

[marksftw]

As a user who has chats that I use on a daily basis, it would be helpful to have those chats at the top of the list so I don't have to go find them. History pagination has made the search box less helpful because it can't find chats that haven't loaded yet. I'll make a separate issue for that (#347). For example, I have a "Proof Read" chat that I use for a final grammar and spelling check before sending out important communications.

Here's a feature spec for Pinned Chats.

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Pinned Chats Feature Specification

Feature Description
Enables users to pin high-priority chats (e.g., daily-use conversations) to keep them permanently visible at the top of the chat history. Pinned chats appear in a dedicated section above the standard history, ensuring immediate access regardless of history pagination or chronological order. This feature addresses usability challenges when searching for frequently used chats (#347).

Key User Flow

• User opens the contextual menu ("…" button) for a chat in history or within an open chat.
• User selects "Pin chat" to pin or "Unpin chat" to unpin.
• Pinned chats appear alphabetically by title in the "Pinned" section above history.
• Unpinned chats return to their chronological position in history.

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Acceptance Criteria

Core Functionality

1. Pin/Unpin Mechanism

   • "Pin chat" option added to the contextual menu ("…" button) for all chats in history and chat headers.
   • Menu dynamically changes to "Unpin chat" for pinned chats.

2. Pinned Section Behavior

   • "Pinned" section appears above "History" only when ≥1 chat is pinned.
   • Section auto-hides when all chats are unpinned, restoring "History" to default position.

3. Sorting & Storage

   • Pinned chats ordered alphabetically by title (case-insensitive, A-Z).
   • Pinned status persists across app restarts, logins, and sessions.
   • Renaming a pinned chat instantly updates its alphabetical position in the "Pinned" section.

4. Edge Handling

   • Maximum of 20 pinned chats per user; exceeding this shows: "Maximum pinned chats reached."
   • Deleting a pinned chat automatically removes it from the "Pinned" section and unpins it.

5. Cross-Device Sync

   • Pin/unpin actions sync in real-time across devices via backend.
   • Conflicts resolved via last-action-wins (e.g., unpin overrides pin if simultaneous).

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Edge Cases to Validate

1. Pinning Limits

   • Attempt pinning a 21st chat → error message appears.
   • Unpin 1 chat → pin a new chat → verify new chat appears without errors.

2. Deletion & Cleanup

   • Delete a pinned chat via history → ensure removed from "Pinned" section and unpinned.
   • Clear all history → verify "Pinned" section disappears and all pins removed.

3. Order & State Conflicts

   • Pin same chat simultaneously from two devices → verify last action wins after sync.

4. Empty Conditions

   • Unpin all chats → verify "Pinned" section disappears instantly.