# Ticket 11.10 — Tool Shimmer Animation for Running Tools

**Phase**: 11 — UI/UX Polish
**Priority**: Low
**Depends on**: None

## Description

The CSS for a tool shimmer animation is defined in style.css (`@keyframes tool-shimmer` and `.tool-activity-shimmer`) but is never applied to any component. Running tool items should have a subtle shimmer/loading effect to visually indicate active processing, similar to claude-relay's shimmer on running tools.

This is a small CSS wiring fix — the animation already exists, it just needs to be applied to ToolItem.svelte when the tool status is "running".

## Acceptance Criteria

### AC1: Running tools display the shimmer animation
```gherkin
Given a tool is currently executing (status is "running")
When the tool item is rendered in the chat
Then the tool item header displays the shimmer animation
And the shimmer is a subtle left-to-right gradient sweep
```

### AC2: Shimmer stops on completion or error
```gherkin
Given a tool item is displaying the shimmer animation
When the tool transitions to "completed" or "error" status
Then the shimmer animation stops
And the tool item displays its final static state
```

### AC3: Pending tools do not shimmer
```gherkin
Given a tool is in "pending" status (queued but not yet running)
When the tool item is rendered in the chat
Then the tool item does not display the shimmer animation
```

### AC4: Shimmer is visually subtle
```gherkin
Given a tool item is displaying the shimmer animation
When the user is reading other content in the chat
Then the shimmer is noticeable but not distracting
And it does not interfere with reading the tool name or status text
```

## Testable Components

| Component | Test Type | What to Assert |
|-----------|-----------|----------------|
| Running tool has shimmer class | E2E | ToolItem with status "running" has the `.tool-activity-shimmer` CSS class on its header |
| Completed tool does not have shimmer class | E2E | ToolItem with status "completed" does not have the `.tool-activity-shimmer` CSS class |
| Pending tool does not have shimmer class | E2E | ToolItem with status "pending" does not have the `.tool-activity-shimmer` CSS class |
| Shimmer animation visual | Storybook | A story renders a ToolItem in "running" state with the shimmer visible |

## Reference

- Existing CSS: `conduit/src/lib/public/style.css` (`@keyframes tool-shimmer`, `.tool-activity-shimmer`)
- ToolItem: `conduit/src/lib/public/components/chat/ToolItem.svelte` (status state machine lines 39-67)
