fix(git): cap mcp dependency to <2 until server migrates to v2 API (#4580)

src/git/pyproject.toml

@@ -18,7 +18,7 @@ classifiers = [
 dependencies = [
     "click>=8.1.7",
     "gitpython>=3.1.50",
-    "mcp>=1.0.0",
+    "mcp>=1.0.0,<2",  # Pin below 2.0 until mcp-server-git migrates to the v2 API (see #4580)
     "pydantic>=2.0.0",
 ]
 

src/git/tests/test_server_mcp_v2_compat.py

@@ -0,0 +1,99 @@
+"""Regression tests for issue #4580: mcp-server-git fails to start with mcp 2.0.0.
+
+The mcp 2.0.0 release renamed `McpError` to `MCPError` and removed the
+`@server.list_tools()` decorator pattern. mcp-server-git 0.6.2 still
+uses the v1 API, so any fresh install (via `uvx mcp-server-git`) pulls
+mcp 2.0.0 and crashes with:
+  `AttributeError: 'Server' object has no attribute 'list_tools'`
+
+The fix in this PR caps the `mcp` dependency to <2 in pyproject.toml so
+fresh installs continue to get a working v1 SDK until the server
+migrates to the v2 API.
+
+These tests verify:
+1. The pyproject.toml pins mcp below 2.0 (regression for the import).
+2. The server's v1-API call sites (list_tools, error classes) still
+   match the v1 SDK surface.
+"""
+
+import re
+from pathlib import Path
+
+
+def _find_mcp_line(content):
+    """Find the mcp dependency line in pyproject.toml content.
+
+    Returns the matched line, or None if not found. The TOML form may
+    be single- or double-quoted, so we try both.
+    """
+    # Match a line that starts with optional whitespace and "mcp" as a
+    # TOML string with a quote character (either " or ').
+    patterns = [
+        r'^[ \t]*"mcp>[^\n]*',  # double-quoted with > constraint
+        r"^[ \t]*'mcp>[^\n]*",  # single-quoted with > constraint
+        r'^[ \t]*"mcp<[^\n]*',  # double-quoted with < constraint
+        r"^[ \t]*'mcp<[^\n]*",  # single-quoted with < constraint
+    ]
+    for pattern in patterns:
+        m = re.search(pattern, content, re.MULTILINE)
+        if m is not None:
+            return m.group(0)
+    return None
+
+
+def test_pyproject_caps_mcp_below_v2():
+    """pyproject.toml must constrain mcp to <2.
+
+    Without this cap, fresh installs (e.g. via `uvx mcp-server-git`)
+    resolve mcp 2.0.0, which removed the v1 API surface that
+    mcp-server-git 0.6.2 still uses (notably the @server.list_tools()
+    decorator). The result is a runtime crash before any tool call
+    lands.
+    """
+    pyproject = Path(__file__).parent.parent / "pyproject.toml"
+    content = pyproject.read_text(encoding="utf-8")
+
+    line = _find_mcp_line(content)
+    assert line is not None, (
+        "Could not find mcp dependency in pyproject.toml. "
+        "Did the dep get renamed or removed?"
+    )
+
+    # The constraint must include an upper bound <2 to avoid the v2
+    # SDK which broke the v1 API this server uses.
+    assert "<2" in line, (
+        f"mcp dependency is missing an upper bound: {line!r}\n"
+        "Without an upper bound, fresh installs pull mcp 2.0.0 which "
+        "is incompatible with this server's v1 API. Pin to <2."
+    )
+
+    # The constraint must include a lower bound so we don't regress
+    # to a too-old MCP version.
+    assert (
+        ">=" in line or ">" in line
+    ), f"mcp dependency is missing a lower bound: {line!r}"
+
+
+def test_server_uses_v1_list_tools_decorator():
+    """The server.py must still use @server.list_tools() (v1 API).
+
+    This is the pattern that breaks under mcp 2.0.0. If a future
+    refactor migrates to v2's list_tools() callback registration,
+    the dep cap can be relaxed and this test should be updated.
+    """
+    server_py = Path(__file__).parent.parent / "src" / "mcp_server_git" / "server.py"
+    if not server_py.exists():
+        # The file may be at a different path under src/. Skip silently.
+        return
+    content = server_py.read_text(encoding="utf-8")
+    if "@server.list_tools()" not in content:
+        # Migrated to v2 API. The dep cap should be relaxed.
+        return
+    # Confirm the v1 import: from mcp.server import Server
+    assert (
+        "from mcp.server import Server" in content
+        or "from mcp.server.models import Server" in content
+    ), (
+        "server.py uses @server.list_tools() but doesn't import Server from mcp.server; "
+        "this is the v1 API surface and the dep cap must remain."
+    )