Reusable widget for panes that need N runtime tab instances of the
same kind. First consumer is the Claude pane (primary + 0..N
secondaries per D-41); the generic shape lets other panes adopt it
later without reinventing tab strips.
Includes:
- Design doc with API sketch, rendering, interaction, persistence
boundary, integration sketch for the Claude pane, and three open
questions (keyboard scoping for nested cases, overflow, density).
- Wireframe of the Claude pane with primary (pinned) + 2 secondaries
+ add button, accent border on the active tab.
- Architecture diagram (sketch mode) showing the host / widget /
controller / IPC boundary that keeps the widget domain-free.
Co-Authored-By: Claude <noreply@anthropic.com>
