Pin pending tool approvals at bottom of viewport

[tcdent]

Problem

When sub-agents request tool approval while the primary agent is outputting text, the approval prompts get pushed up in the transcript and scroll out of view. The user may not notice pending approvals until they stop scrolling.

Current Behavior

The transcript renders linearly - new content (including agent messages) appends to the bottom, pushing earlier content (including pending approval blocks) upward.

Proposed Solution

Keep pending tool approval prompts "pinned" at the bottom of the viewport, visible regardless of other transcript content being added above them.

Possible approaches:

1. Pinned approval zone - A separate UI region at the bottom that always shows pending approvals
2. Notification/overlay system - Surface pending approvals prominently outside the main transcript flow
3. Split rendering - Transcript content above, pending actions below

Related

• PR feat: notifications primitive #49 (notifications primitive) may provide infrastructure for this

Context

This became noticeable with sub-agent support - sub-agents can request tool approval while the primary agent continues responding, making it easy to miss approval prompts.