feat: support ANTHROPIC_BASE_URL for third-party endpoints

* feat: support ANTHROPIC_BASE_URL for third-party Anthropic-compatible endpoints

Allow users to configure a custom base URL for the Anthropic API client
via the ANTHROPIC_BASE_URL environment variable. This enables use with
third-party providers (e.g. z.ai) that expose an Anthropic-compatible
API without modifying the source.

When ANTHROPIC_BASE_URL is not set, behavior is unchanged (default
Anthropic endpoint).

* fix: align README environment variable table columns

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Cobdog

README.md

@@ -213,11 +213,12 @@ After saving the config, **restart Claude Desktop / Claude Code** for the server
 
 Environment variables are optional:
 
-| Variable            | Purpose                                      |
-| ------------------- | -------------------------------------------- |
-| `GITHUB_TOKEN`      | Higher GitHub API limits / private access    |
-| `ANTHROPIC_API_KEY` | AI-generated summaries via Claude Haiku (takes priority) |
-| `GOOGLE_API_KEY`    | AI-generated summaries via Gemini Flash      |
+| Variable             | Purpose                                                  |
+| -------------------- | -------------------------------------------------------- |
+| `GITHUB_TOKEN`       | Higher GitHub API limits / private access                |
+| `ANTHROPIC_API_KEY`  | AI-generated summaries via Claude Haiku (takes priority) |
+| `ANTHROPIC_BASE_URL` | Third-party Anthropic-compatible endpoints (e.g. z.ai)   |
+| `GOOGLE_API_KEY`     | AI-generated summaries via Gemini Flash                  |
 
 ---
 
@@ -362,6 +363,7 @@ For **LM Studio**, ensure the Local Server is running (usually on port 1234):
 | --------------------------- | ------------------------- | -------- |
 | `GITHUB_TOKEN`              | GitHub API auth           | No       |
 | `ANTHROPIC_API_KEY`         | Symbol summaries via Claude Haiku (takes priority) | No       |
+| `ANTHROPIC_BASE_URL`        | Third-party Anthropic-compatible endpoints (e.g. z.ai) | No       |
 | `GOOGLE_API_KEY`            | Symbol summaries via Gemini Flash | No       |
 | `OPENAI_API_BASE`           | Base URL for local LLMs (e.g. `http://localhost:11434/v1`) | No |
 | `OPENAI_API_KEY`            | API key for local LLMs (default: `local-llm`) | No |

src/jcodemunch_mcp/summarizer/batch_summarize.py

@@ -63,7 +63,11 @@ def _init_client(self):
             from anthropic import Anthropic
             api_key = os.environ.get("ANTHROPIC_API_KEY")
             if api_key:
-                self.client = Anthropic(api_key=api_key)
+                base_url = os.environ.get("ANTHROPIC_BASE_URL")
+                kwargs = {"api_key": api_key}
+                if base_url:
+                    kwargs["base_url"] = base_url
+                self.client = Anthropic(**kwargs)
         except ImportError:
             if os.environ.get("ANTHROPIC_API_KEY"):
                 import warnings

tests/test_summarizer.py

@@ -110,6 +110,46 @@ def test_simple_summarize_fallback_to_signature():
     assert "def foo" in result[0].summary
 
 
+def test_anthropic_summarizer_base_url():
+    """BatchSummarizer passes ANTHROPIC_BASE_URL to Anthropic client when set."""
+    import sys
+
+    mock_anthropic_module = MagicMock()
+    mock_client = MagicMock()
+    mock_anthropic_module.Anthropic.return_value = mock_client
+
+    with patch.dict(sys.modules, {"anthropic": mock_anthropic_module}):
+        with patch.dict("os.environ", {
+            "ANTHROPIC_API_KEY": "sk-test-key",
+            "ANTHROPIC_BASE_URL": "https://proxy.example.com/v1",
+        }, clear=True):
+            from jcodemunch_mcp.summarizer.batch_summarize import BatchSummarizer
+            summarizer = BatchSummarizer()
+
+    mock_anthropic_module.Anthropic.assert_called_once_with(
+        api_key="sk-test-key",
+        base_url="https://proxy.example.com/v1",
+    )
+    assert summarizer.client is mock_client
+
+
+def test_anthropic_summarizer_no_base_url():
+    """BatchSummarizer omits base_url when ANTHROPIC_BASE_URL is not set."""
+    import sys
+
+    mock_anthropic_module = MagicMock()
+    mock_client = MagicMock()
+    mock_anthropic_module.Anthropic.return_value = mock_client
+
+    with patch.dict(sys.modules, {"anthropic": mock_anthropic_module}):
+        with patch.dict("os.environ", {"ANTHROPIC_API_KEY": "sk-test-key"}, clear=True):
+            from jcodemunch_mcp.summarizer.batch_summarize import BatchSummarizer
+            summarizer = BatchSummarizer()
+
+    mock_anthropic_module.Anthropic.assert_called_once_with(api_key="sk-test-key")
+    assert summarizer.client is mock_client
+
+
 def test_gemini_summarizer_no_api_key():
     """GeminiBatchSummarizer falls back to signature when no API key is set."""
     with patch.dict("os.environ", {}, clear=True):