sub(#250) Phase 1: ToolResultRenderer extension point and default renderers

[mmogr]

Summary

Add a ToolResultRenderer extension point to the tool registry so each tool can declare how its results should be rendered in the chat UI. Implement default renderers for built-in tools.

Context

Currently, all tool results are rendered as plain JSON text in the chat UI. The summarizeToolResult function in agentLoop.ts simply stringifies res.data and truncates it. There's no per-tool rendering — a web search result, a file listing, and a model info response all look the same.

Proposed Changes

1. Define ToolResultRenderer interface

// src/services/tools/types.ts

export interface ToolResultRenderer {
  /** Render tool result into a React node for display in chat */
  renderResult(data: unknown, toolName: string): React.ReactNode;
  /** Optional: render a compact inline summary (for collapsed view) */
  renderSummary?(data: unknown, toolName: string): string;
}

2. Extend ToolRegistration to accept a renderer

// src/services/tools/types.ts - extend existing ToolRegistration
export interface ToolRegistration {
  // ... existing fields ...
  renderer?: ToolResultRenderer;
}

3. Extend ToolRegistry to store/retrieve renderers

// src/services/tools/registry.ts

class ToolRegistry {
  // ... existing code ...
  
  getRenderer(toolName: string): ToolResultRenderer | undefined {
    return this.tools.get(toolName)?.renderer;
  }
}

4. Implement default renderers for built-in tools

Create renderers for the core tools:

Tool	Renderer
web_search	Card list with title, URL, snippet
fetch_url	Content preview with domain badge
read_file	Syntax-highlighted code block with filename header
list_directory	File tree view
execute_command	Terminal-style output block with exit code badge
Generic fallback	Pretty-printed JSON with collapsible sections

5. Create src/services/tools/renderers/ directory

src/services/tools/renderers/
├── index.ts              # Re-exports all renderers
├── FallbackRenderer.tsx  # Generic JSON renderer (default)
├── WebSearchRenderer.tsx # web_search results
├── FileRenderer.tsx      # read_file results  
├── CommandRenderer.tsx   # execute_command results
└── DirectoryRenderer.tsx # list_directory results

Files to Create/Modify

File	Change
src/services/tools/types.ts	Add ToolResultRenderer interface
src/services/tools/registry.ts	Add getRenderer() method
src/services/tools/renderers/	Create renderer directory with implementations
src/services/tools/builtinTools.ts (or equivalent)	Attach renderers when registering built-in tools

Acceptance Criteria

• ToolResultRenderer interface defined with renderResult and optional renderSummary
• ToolRegistration extended with optional renderer field
• ToolRegistry.getRenderer() method available
• At least 3 built-in tool renderers implemented (web_search, read_file, execute_command)
• Fallback renderer handles any unknown tool result as pretty-printed JSON
• Renderers are tree-shakeable (lazy-loaded or conditionally imported)
• Unit tests for each renderer with sample tool result data