[UX] Attachment Copy Disambiguation

[mishudark]

Problem Statement

When a user message contains both text content and attachments (particularly text-based attachments like pasted code), pressing c or y to copy creates ambiguity:

• Current behavior: Only message text is copied
• User confusion: No visual indication of what will be copied

Scenarios

1. Pasted long text → Creates paste_1.txt attachment

   • User may want to copy the original pasted content
   • OR the message text they typed

2. Multiple attachments → User may want:

   • Specific attachment content
   • All attachments
   • Message text only
   • Combined content

3. Mixed attachments (images + text files) → Different copy needs for each type

Proposed Solution

Phase 1: Index-Based Attachment Selection (MVP)

UX Flow:

[User presses 'c' or 'y' on message with attachments]
         ↓
[Show ephemeral status: "Press 0-9 to copy attachment, Enter for message text"]
         ↓
[User presses number → Copy attachment N content]
[User presses Enter → Copy message text (original behavior)]
[User presses Esc → Cancel]

Key Bindings:

State	Key	Action
Normal	c/y	Initiate copy mode if attachments exist
Copy Mode	0-9	Copy attachment at index (if text type) or path (if binary)
Copy Mode	Enter/c/y	Copy message text (default)
Copy Mode	Esc	Cancel copy mode
Copy Mode	a	Copy ALL text attachment contents concatenated

Visual Indicator:

When copy mode is active, temporarily highlight attachments with their index numbers:

[Message text here...]

📄 paste_001.txt [0]  📄 config.yaml [1]  🖼️ screenshot.png [2]

Phase 2: Enhanced Selection UI (Future)

• Visual selection overlay on attachments
• Preview of what will be copied
• "Copy as" options (raw content, file path, markdown link)

Acceptance Criteria

Must Have (MVP)

• Pressing c/y on message without attachments copies message text (existing behavior)
• Pressing c/y on message with attachments enters "copy selection mode"
• In copy selection mode, numbered keys (0-9) copy specific attachment:
  • Text attachments: copy content
  • Binary attachments: copy file path
• In copy selection mode, Enter or second c/y copies message text
• In copy selection mode, Esc cancels without copying
• Visual feedback shows attachment indices during selection mode
• Status message indicates what was copied ("Attachment 0 copied", "Message text copied")

Should Have

• Key a copies ALL text attachment contents (concatenated with separators)
• If only ONE text attachment exists, c/y copies it directly (no selection mode)

Code

#2170