test: comprehensive tests for model metadata + firecrawl config

model_metadata tests (61 tests, was 39):
  - Token estimation: concrete value assertions, unicode, tool_call messages,
    vision multimodal content, additive verification
  - Context length resolution: cache-over-API priority, no-base_url skips cache,
    missing context_length key in API response
  - API metadata fetch: canonical_slug aliasing, TTL expiry with time mock,
    stale cache fallback on API failure, malformed JSON resilience
  - Probe tiers: above-max returns 2M, zero returns None
  - Error parsing: Anthropic format ('X > Y maximum'), LM Studio, empty string,
    unreasonably large numbers — also fixed parser to handle Anthropic format
  - Cache: corruption resilience (garbage YAML, wrong structure), value updates,
    special chars in model names

Firecrawl config tests (8 tests, was 4):
  - Singleton caching (core purpose — verified constructor called once)
  - Constructor failure recovery (retry after exception)
  - Return value actually asserted (not just constructor args)
  - Empty string env vars treated as absent
  - Proper setup/teardown for env var isolation

tests/tools/test_web_tools_config.py

@@ -1,4 +1,9 @@
-"""Tests for Firecrawl client configuration."""
+"""Tests for Firecrawl client configuration and singleton behavior.
+
+Coverage:
+  _get_firecrawl_client() — configuration matrix, singleton caching,
+  constructor failure recovery, return value verification, edge cases.
+"""
 
 import os
 import pytest
@@ -6,69 +11,109 @@ from unittest.mock import patch, MagicMock
 
 
 class TestFirecrawlClientConfig:
-    """Test suite for Firecrawl client initialization with API URL support."""
+    """Test suite for Firecrawl client initialization."""
 
-    def teardown_method(self):
-        """Reset client between tests."""
+    def setup_method(self):
+        """Reset client and env vars before each test."""
         import tools.web_tools
-
         tools.web_tools._firecrawl_client = None
-
-    def _clear_firecrawl_env(self):
-        """Remove Firecrawl env vars so tests start clean."""
         for key in ("FIRECRAWL_API_KEY", "FIRECRAWL_API_URL"):
             os.environ.pop(key, None)
 
-    def test_client_with_api_key_only(self):
-        """Test client initialization with only API key (cloud mode)."""
-        self._clear_firecrawl_env()
-        with patch.dict(os.environ, {"FIRECRAWL_API_KEY": "test-key"}, clear=False):
-            with patch("tools.web_tools.Firecrawl") as mock_firecrawl:
+    def teardown_method(self):
+        """Reset client after each test."""
+        import tools.web_tools
+        tools.web_tools._firecrawl_client = None
+        for key in ("FIRECRAWL_API_KEY", "FIRECRAWL_API_URL"):
+            os.environ.pop(key, None)
+
+    # ── Configuration matrix ─────────────────────────────────────────
+
+    def test_cloud_mode_key_only(self):
+        """API key without URL → cloud Firecrawl."""
+        with patch.dict(os.environ, {"FIRECRAWL_API_KEY": "fc-test"}):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
                 from tools.web_tools import _get_firecrawl_client
+                result = _get_firecrawl_client()
+                mock_fc.assert_called_once_with(api_key="fc-test")
+                assert result is mock_fc.return_value
 
-                _get_firecrawl_client()
-                mock_firecrawl.assert_called_once_with(api_key="test-key")
-
-    def test_client_with_api_key_and_url(self):
-        """Test client initialization with API key and custom URL."""
-        self._clear_firecrawl_env()
-        with patch.dict(
-            os.environ,
-            {
-                "FIRECRAWL_API_KEY": "test-key",
-                "FIRECRAWL_API_URL": "http://localhost:3002",
-            },
-            clear=False,
-        ):
-            with patch("tools.web_tools.Firecrawl") as mock_firecrawl:
+    def test_self_hosted_with_key(self):
+        """Both key + URL → self-hosted with auth."""
+        with patch.dict(os.environ, {
+            "FIRECRAWL_API_KEY": "fc-test",
+            "FIRECRAWL_API_URL": "http://localhost:3002",
+        }):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
                 from tools.web_tools import _get_firecrawl_client
-
-                _get_firecrawl_client()
-                mock_firecrawl.assert_called_once_with(
-                    api_key="test-key", api_url="http://localhost:3002"
+                result = _get_firecrawl_client()
+                mock_fc.assert_called_once_with(
+                    api_key="fc-test", api_url="http://localhost:3002"
                 )
+                assert result is mock_fc.return_value
 
-    def test_client_with_url_only_no_key(self):
-        """Self-hosted mode: URL without API key should work."""
-        self._clear_firecrawl_env()
-        with patch.dict(
-            os.environ,
-            {"FIRECRAWL_API_URL": "http://localhost:3002"},
-            clear=False,
-        ):
-            with patch("tools.web_tools.Firecrawl") as mock_firecrawl:
+    def test_self_hosted_no_key(self):
+        """URL only, no key → self-hosted without auth."""
+        with patch.dict(os.environ, {"FIRECRAWL_API_URL": "http://localhost:3002"}):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
                 from tools.web_tools import _get_firecrawl_client
+                result = _get_firecrawl_client()
+                mock_fc.assert_called_once_with(api_url="http://localhost:3002")
+                assert result is mock_fc.return_value
 
-                _get_firecrawl_client()
-                mock_firecrawl.assert_called_once_with(
-                    api_url="http://localhost:3002"
-                )
-
-    def test_no_key_no_url_raises(self):
-        """Neither key nor URL set should raise a clear error."""
-        self._clear_firecrawl_env()
+    def test_no_config_raises_with_helpful_message(self):
+        """Neither key nor URL → ValueError with guidance."""
         with patch("tools.web_tools.Firecrawl"):
             from tools.web_tools import _get_firecrawl_client
-
             with pytest.raises(ValueError, match="FIRECRAWL_API_KEY"):
                 _get_firecrawl_client()
+
+    # ── Singleton caching ────────────────────────────────────────────
+
+    def test_singleton_returns_same_instance(self):
+        """Second call returns cached client without re-constructing."""
+        with patch.dict(os.environ, {"FIRECRAWL_API_KEY": "fc-test"}):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
+                from tools.web_tools import _get_firecrawl_client
+                client1 = _get_firecrawl_client()
+                client2 = _get_firecrawl_client()
+                assert client1 is client2
+                mock_fc.assert_called_once()  # constructed only once
+
+    def test_constructor_failure_allows_retry(self):
+        """If Firecrawl() raises, next call should retry (not return None)."""
+        import tools.web_tools
+        with patch.dict(os.environ, {"FIRECRAWL_API_KEY": "fc-test"}):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
+                mock_fc.side_effect = [RuntimeError("init failed"), MagicMock()]
+                from tools.web_tools import _get_firecrawl_client
+
+                with pytest.raises(RuntimeError):
+                    _get_firecrawl_client()
+
+                # Client stayed None, so retry should work
+                assert tools.web_tools._firecrawl_client is None
+                result = _get_firecrawl_client()
+                assert result is not None
+
+    # ── Edge cases ───────────────────────────────────────────────────
+
+    def test_empty_string_key_treated_as_absent(self):
+        """FIRECRAWL_API_KEY='' should not be passed as api_key."""
+        with patch.dict(os.environ, {
+            "FIRECRAWL_API_KEY": "",
+            "FIRECRAWL_API_URL": "http://localhost:3002",
+        }):
+            with patch("tools.web_tools.Firecrawl") as mock_fc:
+                from tools.web_tools import _get_firecrawl_client
+                _get_firecrawl_client()
+                # Empty string is falsy, so only api_url should be passed
+                mock_fc.assert_called_once_with(api_url="http://localhost:3002")
+
+    def test_empty_string_key_no_url_raises(self):
+        """FIRECRAWL_API_KEY='' with no URL → should raise."""
+        with patch.dict(os.environ, {"FIRECRAWL_API_KEY": ""}):
+            with patch("tools.web_tools.Firecrawl"):
+                from tools.web_tools import _get_firecrawl_client
+                with pytest.raises(ValueError):
+                    _get_firecrawl_client()