fix: remove dead airllm provider type from cascade router

Remove the airllm provider block from providers.yaml, the airllm
availability check from cascade.py, and associated tests. Renumber
remaining provider priorities (OpenAI → 2, Anthropic → 3).

Fixes #459

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

config/providers.yaml

@@ -54,25 +54,11 @@ providers:
         context_window: 2048
         capabilities: [text, vision, streaming]
     
-  # Secondary: Local AirLLM (if installed)
-  - name: airllm-local
-    type: airllm
-    enabled: false  # Enable if pip install airllm
-    priority: 2
-    models:
-      - name: 70b
-        default: true
-        capabilities: [text, tools, json, streaming]
-      - name: 8b
-        capabilities: [text, tools, json, streaming]
-      - name: 405b
-        capabilities: [text, tools, json, streaming]
-    
-  # Tertiary: OpenAI (if API key available)
+  # Secondary: OpenAI (if API key available)
   - name: openai-backup
     type: openai
     enabled: false  # Enable by setting OPENAI_API_KEY
-    priority: 3
+    priority: 2
     api_key: "${OPENAI_API_KEY}"  # Loaded from environment
     base_url: null  # Use default OpenAI endpoint
     models:
@@ -84,11 +70,11 @@ providers:
         context_window: 128000
         capabilities: [text, vision, tools, json, streaming]
     
-  # Quaternary: Anthropic (if API key available)
+  # Tertiary: Anthropic (if API key available)
   - name: anthropic-backup
     type: anthropic
     enabled: false  # Enable by setting ANTHROPIC_API_KEY
-    priority: 4
+    priority: 3
     api_key: "${ANTHROPIC_API_KEY}"
     models:
       - name: claude-3-haiku-20240307

src/infrastructure/router/cascade.py

@@ -100,7 +100,7 @@ class Provider:
     """LLM provider configuration and state."""
 
     name: str
-    type: str  # ollama, openai, anthropic, airllm
+    type: str  # ollama, openai, anthropic
     enabled: bool
     priority: int
     url: str | None = None
@@ -308,15 +308,6 @@ class CascadeRouter:
                 logger.debug("Ollama provider check error: %s", exc)
                 return False
 
-        elif provider.type == "airllm":
-            # Check if airllm is installed
-            try:
-                import importlib.util
-
-                return importlib.util.find_spec("airllm") is not None
-            except (ImportError, ModuleNotFoundError):
-                return False
-
         elif provider.type in ("openai", "anthropic", "grok"):
             # Check if API key is set
             return provider.api_key is not None and provider.api_key != ""

tests/infrastructure/test_router_cascade.py

@@ -2,7 +2,7 @@
 
 import time
 from pathlib import Path
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
 import yaml
@@ -489,34 +489,6 @@ class TestProviderAvailabilityCheck:
 
         assert router._check_provider_available(provider) is False
 
-    def test_check_airllm_installed(self):
-        """Test AirLLM when installed."""
-        router = CascadeRouter(config_path=Path("/nonexistent"))
-
-        provider = Provider(
-            name="airllm",
-            type="airllm",
-            enabled=True,
-            priority=1,
-        )
-
-        with patch("importlib.util.find_spec", return_value=MagicMock()):
-            assert router._check_provider_available(provider) is True
-
-    def test_check_airllm_not_installed(self):
-        """Test AirLLM when not installed."""
-        router = CascadeRouter(config_path=Path("/nonexistent"))
-
-        provider = Provider(
-            name="airllm",
-            type="airllm",
-            enabled=True,
-            priority=1,
-        )
-
-        with patch("importlib.util.find_spec", return_value=None):
-            assert router._check_provider_available(provider) is False
-
 
 class TestCascadeRouterReload:
     """Test hot-reload of providers.yaml."""