feat: Add global settings modal and simplify agent controls

Adds a settings system for global configuration with YOLO mode toggle and
model selection. Simplifies the agent control UI by removing redundant
status indicator and pause functionality.

## Settings System
- New SettingsModal with YOLO mode toggle and model selection
- Settings persisted in SQLite (registry.db) - shared across all projects
- Models fetched from API endpoint (/api/settings/models)
- Single source of truth for models in registry.py - easy to add new models
- Optimistic UI updates with rollback on error

## Agent Control Simplification
- Removed StatusIndicator ("STOPPED"/"RUNNING" label) - redundant
- Removed Pause/Resume buttons - just Start/Stop toggle now
- Start button shows flame icon with fiery gradient when YOLO mode enabled

## Code Review Fixes
- Added focus trap to SettingsModal for accessibility
- Fixed YOLO button color contrast (WCAG AA compliance)
- Added model validation to AgentStartRequest schema
- Added model to AgentStatus response
- Added aria-labels to all icon-only buttons
- Added role="radiogroup" to model selection
- Added loading indicator during settings save
- Added SQLite timeout (30s) and retry logic with exponential backoff
- Added thread-safe database engine initialization
- Added orphaned lock file cleanup on server startup

## Files Changed
- registry.py: Model config, Settings CRUD, SQLite improvements
- server/routers/settings.py: New settings API
- server/schemas.py: Settings schemas with validation
- server/services/process_manager.py: Model param, orphan cleanup
- ui/src/components/SettingsModal.tsx: New modal component
- ui/src/components/AgentControl.tsx: Simplified to Start/Stop only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server/routers/__init__.py

@@ -10,6 +10,7 @@ from .assistant_chat import router as assistant_chat_router
 from .features import router as features_router
 from .filesystem import router as filesystem_router
 from .projects import router as projects_router
+from .settings import router as settings_router
 from .spec_creation import router as spec_creation_router
 
 __all__ = [
@@ -19,4 +20,5 @@ __all__ = [
     "spec_creation_router",
     "filesystem_router",
     "assistant_chat_router",
+    "settings_router",
 ]

server/routers/agent.py

@@ -26,6 +26,21 @@ def _get_project_path(project_name: str) -> Path:
     return get_project_path(project_name)
 
 
+def _get_settings_defaults() -> tuple[bool, str]:
+    """Get YOLO mode and model defaults from global settings."""
+    import sys
+    root = Path(__file__).parent.parent.parent
+    if str(root) not in sys.path:
+        sys.path.insert(0, str(root))
+
+    from registry import DEFAULT_MODEL, get_all_settings
+
+    settings = get_all_settings()
+    yolo_mode = (settings.get("yolo_mode") or "false").lower() == "true"
+    model = settings.get("model", DEFAULT_MODEL)
+    return yolo_mode, model
+
+
 router = APIRouter(prefix="/api/projects/{project_name}/agent", tags=["agent"])
 
 # Root directory for process manager
@@ -69,6 +84,7 @@ async def get_agent_status(project_name: str):
         pid=manager.pid,
         started_at=manager.started_at,
         yolo_mode=manager.yolo_mode,
+        model=manager.model,
     )
 
 
@@ -80,7 +96,12 @@ async def start_agent(
     """Start the agent for a project."""
     manager = get_project_manager(project_name)
 
-    success, message = await manager.start(yolo_mode=request.yolo_mode)
+    # Get defaults from global settings if not provided in request
+    default_yolo, default_model = _get_settings_defaults()
+    yolo_mode = request.yolo_mode if request.yolo_mode is not None else default_yolo
+    model = request.model if request.model else default_model
+
+    success, message = await manager.start(yolo_mode=yolo_mode, model=model)
 
     return AgentActionResponse(
         success=success,

server/routers/settings.py

@@ -0,0 +1,75 @@
+"""
+Settings Router
+===============
+
+API endpoints for global settings management.
+Settings are stored in the registry database and shared across all projects.
+"""
+
+import sys
+from pathlib import Path
+
+from fastapi import APIRouter
+
+from ..schemas import ModelInfo, ModelsResponse, SettingsResponse, SettingsUpdate
+
+# Add root to path for registry import
+ROOT_DIR = Path(__file__).parent.parent.parent
+if str(ROOT_DIR) not in sys.path:
+    sys.path.insert(0, str(ROOT_DIR))
+
+from registry import (
+    AVAILABLE_MODELS,
+    DEFAULT_MODEL,
+    DEFAULT_YOLO_MODE,
+    get_all_settings,
+    set_setting,
+)
+
+router = APIRouter(prefix="/api/settings", tags=["settings"])
+
+
+def _parse_yolo_mode(value: str | None) -> bool:
+    """Parse YOLO mode string to boolean."""
+    return (value or "false").lower() == "true"
+
+
+@router.get("/models", response_model=ModelsResponse)
+async def get_available_models():
+    """Get list of available models.
+
+    Frontend should call this to get the current list of models
+    instead of hardcoding them.
+    """
+    return ModelsResponse(
+        models=[ModelInfo(id=m["id"], name=m["name"]) for m in AVAILABLE_MODELS],
+        default=DEFAULT_MODEL,
+    )
+
+
+@router.get("", response_model=SettingsResponse)
+async def get_settings():
+    """Get current global settings."""
+    all_settings = get_all_settings()
+
+    return SettingsResponse(
+        yolo_mode=_parse_yolo_mode(all_settings.get("yolo_mode")),
+        model=all_settings.get("model", DEFAULT_MODEL),
+    )
+
+
+@router.patch("", response_model=SettingsResponse)
+async def update_settings(update: SettingsUpdate):
+    """Update global settings."""
+    if update.yolo_mode is not None:
+        set_setting("yolo_mode", "true" if update.yolo_mode else "false")
+
+    if update.model is not None:
+        set_setting("model", update.model)
+
+    # Return updated settings
+    all_settings = get_all_settings()
+    return SettingsResponse(
+        yolo_mode=_parse_yolo_mode(all_settings.get("yolo_mode")),
+        model=all_settings.get("model", DEFAULT_MODEL),
+    )