feat: redesign tool confirmation as fixed bottom bar with fullscreen mode

[platypusrex]

Problem

When the model sends 10+ tool calls, the ConfirmingView renders inline inside the scrollbox message list (tool-message.tsx line 634). The confirmation UI gets buried off-screen and users must scroll to find it. This is especially bad for sequential unsafe tools (write_file, run_command) where each stacks a pending->confirming sequence.

The InputBox is already disabled during confirmation (index.tsx line 480), so it occupies space for no reason.

Solution

Replace the inline ConfirmingView with a fixed-position ConfirmationBar that replaces the InputBox during confirmation. Add Ctrl+F fullscreen toggle for reviewing large diffs.

Normal confirmation mode (~20 lines)

+-------------------------------------+-----------+
| <scrollbox> (chat messages)         | SidePanel |
| ...                                 |           |
+------------------------------ ------+           |
| ConfirmationBar (~20 lines)         |           |
|   triangle write_file src/foo.ts    |           |
|   +---------------------------+     |           |
|   | scrollable diff preview   |     |           |
|   | ...                       |     |           |
|   +---------------------------+     |           |
|   [Y]es [N]o [A]lways              |           |
|             Ctrl+F: fullscreen      |           |
+------------------------------ ------+-----------+

• Replaces InputBox (which is disabled during confirmation anyway)
• Shows: tool header, scrollable diff/command preview (~20 lines), [Y]es [N]o [A]lways buttons
• Ctrl+F hint at bottom

Fullscreen mode (Ctrl+F toggle)

+------------------------------------------------+
| ConfirmationBar (full terminal)                |
|   triangle write_file src/foo.ts               |
|   +------------------------------------------+ |
|   | full scrollable diff preview             | |
|   | ...                                      | |
|   | ...                                      | |
|   +------------------------------------------+ |
|   [Y]es [N]o [A]lways                         |
|              Ctrl+F: exit fullscreen           |
+------------------------------------------------+

• Hides scrollbox AND SidePanel
• ConfirmationBar fills entire terminal with flexGrow={1}
• Full scrollable diff preview with maximum width
• Ctrl+F returns to normal mode
• Y/N/A/Esc still work in fullscreen

Inline indicator

The ToolMessage confirming case shows a minimal InlineTool:

triangle write_file src/foo.ts (awaiting confirmation...)

No keyboard handler, no preview inline — all interaction moves to the bottom bar.

File Changes

File	Change
src/tui/components/confirmation-bar.tsx	New — standalone component with scrollable preview, action buttons, keyboard handler (Y/N/A/Ctrl+F)
src/tui/components/tool-message.tsx	Remove ConfirmingView component entirely. Confirming case in ToolMessage switch returns InlineTool with suffix="(awaiting confirmation...)". Remove onConfirmationResponse, isActiveConfirmation, isModalOpen from ToolMessageProps.
src/tui/components/index.ts	Add ConfirmationBar export
src/tui/index.tsx	Add confirmationFullscreen signal. Derive confirmingMessage from displayMessages() + confirmingToolId(). Wrap <scrollbox> in <Show when={!confirmationFullscreen()}>. Wrap <SidePanel> in <Show when={!confirmationFullscreen()}>. In flexShrink={0} container: <Show when={confirmingToolId()} fallback={<InputBox .../>}> renders <ConfirmationBar>. When fullscreen, bar gets flexGrow={1}. Remove isActiveConfirmation, onConfirmationResponse, isModalOpen props from <ToolMessage> usage.

Data Flow

1. onConfirmationNeeded -> setConfirmingToolId(toolId) + tool state becomes 'confirming'
2. confirmingToolId() is non-null -> InputBox hides, ConfirmationBar renders
3. ConfirmationBar finds its ToolDisplayMessage from displayMessages() by matching ID
4. User presses Ctrl+F -> confirmationFullscreen toggles -> scrollbox + sidebar hide/show
5. User presses Y/N/A -> handleToolConfirmation() -> clears confirmingToolId -> bar unmounts, InputBox returns
6. If fullscreen was active, it auto-resets when confirmation clears

Keyboard

Key	Action
Y	Allow tool execution
N / Esc / Q	Deny tool execution
A	Always allow this tool type
Ctrl+F	Toggle fullscreen preview

Acceptance Criteria

• Confirmation bar replaces InputBox during confirmation
• Diff preview is scrollable within the ~20 line compact height
• Command preview shows $ command with cwd
• Ctrl+F toggles fullscreen (hides scrollbox + sidebar)
• Ctrl+F again returns to normal mode
• Y/N/A work in both normal and fullscreen modes
• Inline ToolMessage shows "awaiting confirmation..." indicator (no preview, no keyboard)
• When 10+ tool calls stack, confirmation is always visible at bottom
• Fullscreen auto-clears when confirmation resolves
• No regressions: modal suppression still works (command menu / session picker open -> keys suppressed)

Related

Part of the message history consistency work (#56). The current inline confirmation stacking was identified as a UX issue during Phase 7 testing.