feat(git): add git_current_branch, git_default_branch, and git_remote tools

Add three new tools to the Git MCP server:

- git_current_branch: Returns the active branch name, or the short
  SHA with a detached HEAD indicator when HEAD is detached.
- git_default_branch: Determines the default branch for a remote,
  returning in 'remote/branch' format (e.g. 'origin/main'). Uses
  git ls-remote --symref (parsed via regex), with fallback to
  rev-parse for local ref resolution, then common branch name
  detection. Accepts an optional remote parameter (defaults to
  "origin").
- git_remote: Lists all configured remotes with their fetch and
  push URLs (wraps git remote -v).

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

Author: cblecker

src/git/src/mcp_server_git/server.py

@@ -1,4 +1,5 @@
 import logging
+import re
 from pathlib import Path
 from typing import Sequence, Optional
 from mcp.server import Server
@@ -93,6 +94,19 @@ class GitBranch(BaseModel):
     )
 
 
+class GitCurrentBranch(BaseModel):
+    repo_path: str
+
+class GitDefaultBranch(BaseModel):
+    repo_path: str
+    remote: str = Field(
+        "origin",
+        description="The remote to get the default branch for (defaults to 'origin')"
+    )
+
+class GitRemote(BaseModel):
+    repo_path: str
+
 class GitTools(str, Enum):
     STATUS = "git_status"
     DIFF_UNSTAGED = "git_diff_unstaged"
@@ -107,6 +121,9 @@ class GitTools(str, Enum):
     SHOW = "git_show"
 
     BRANCH = "git_branch"
+    CURRENT_BRANCH = "git_current_branch"
+    DEFAULT_BRANCH = "git_default_branch"
+    REMOTE = "git_remote"
 
 def git_status(repo: git.Repo) -> str:
     return repo.git.status()
@@ -289,6 +306,42 @@ def git_branch(repo: git.Repo, branch_type: str, contains: str | None = None, no
 
     return branch_info
 
+def git_current_branch(repo: git.Repo) -> str:
+    if repo.head.is_detached:
+        return f"HEAD detached at {repo.head.commit.hexsha[:7]}"
+    return repo.active_branch.name
+
+def git_default_branch(repo: git.Repo, remote: str = "origin") -> str:
+    # Try git ls-remote --symref to detect remote HEAD
+    try:
+        output = repo.git.ls_remote("--symref", remote, "HEAD")
+        # Output format: "ref: refs/heads/main\tHEAD\n<sha>\tHEAD"
+        match = re.search(r"^ref: refs/heads/(\S+)\t", output, re.MULTILINE)
+        if match:
+            return f"{remote}/{match.group(1)}"
+    except git.GitCommandError:
+        pass
+
+    # Try local ref resolution via rev-parse (returns "origin/main" directly)
+    try:
+        return repo.git.rev_parse("--abbrev-ref", f"{remote}/HEAD")
+    except git.GitCommandError:
+        pass
+
+    # Fallback: check for common local branch names
+    local_branches = [ref.name for ref in repo.branches]
+    if "main" in local_branches:
+        return f"{remote}/main"
+    if "master" in local_branches:
+        return f"{remote}/master"
+
+    raise ValueError(
+        f"Could not determine the default branch for remote '{remote}'"
+    )
+
+def git_remote(repo: git.Repo) -> str:
+    return repo.git.remote("-v")
+
 
 async def serve(repository: Path | None) -> None:
     logger = logging.getLogger(__name__)
@@ -437,7 +490,22 @@ async def list_tools() -> list[Tool]:
                     idempotentHint=True,
                     openWorldHint=False,
                 ),
-            )
+            ),
+            Tool(
+                name=GitTools.CURRENT_BRANCH,
+                description="Returns the name of the currently checked out branch, or the commit SHA if HEAD is detached",
+                inputSchema=GitCurrentBranch.model_json_schema(),
+            ),
+            Tool(
+                name=GitTools.DEFAULT_BRANCH,
+                description="Returns the default branch for a remote in '<remote>/<branch>' format (e.g., 'origin/main'). Queries the remote directly, with fallback to local ref resolution and branch detection.",
+                inputSchema=GitDefaultBranch.model_json_schema(),
+            ),
+            Tool(
+                name=GitTools.REMOTE,
+                description="Lists all configured remotes with their fetch and push URLs",
+                inputSchema=GitRemote.model_json_schema(),
+            ),
         ]
 
     async def list_repos() -> Sequence[str]:
@@ -579,6 +647,30 @@ async def call_tool(name: str, arguments: dict) -> list[TextContent]:
                     text=result
                 )]
 
+            case GitTools.CURRENT_BRANCH:
+                result = git_current_branch(repo)
+                return [TextContent(
+                    type="text",
+                    text=result
+                )]
+
+            case GitTools.DEFAULT_BRANCH:
+                result = git_default_branch(
+                    repo,
+                    arguments.get("remote", "origin")
+                )
+                return [TextContent(
+                    type="text",
+                    text=result
+                )]
+
+            case GitTools.REMOTE:
+                result = git_remote(repo)
+                return [TextContent(
+                    type="text",
+                    text=result
+                )]
+
             case _:
                 raise ValueError(f"Unknown tool: {name}")
 

src/git/tests/test_server.py

@@ -5,6 +5,9 @@
 from mcp_server_git.server import (
     git_checkout,
     git_branch,
+    git_current_branch,
+    git_default_branch,
+    git_remote,
     git_add,
     git_status,
     git_diff_unstaged,
@@ -482,3 +485,145 @@ def test_git_branch_rejects_contains_flag_injection(test_repository):
 
     with pytest.raises(BadName):
         git_branch(test_repository, "local", not_contains="--exec=evil")
+
+
+# Tests for git_current_branch
+
+def test_git_current_branch(test_repository):
+    result = git_current_branch(test_repository)
+    assert result == test_repository.active_branch.name
+
+def test_git_current_branch_detached_head(test_repository):
+    commit_sha = test_repository.head.commit.hexsha
+    test_repository.git.checkout(commit_sha)
+    result = git_current_branch(test_repository)
+    assert "detached" in result.lower()
+    assert commit_sha[:7] in result
+
+
+# Tests for git_default_branch
+
+def test_git_default_branch_fallback_local(test_repository):
+    """Repo with no remote; falls back to detecting the local default branch name."""
+    default_branch = test_repository.active_branch.name
+    result = git_default_branch(test_repository)
+    assert result == f"origin/{default_branch}"
+
+def test_git_default_branch_with_remote(tmp_path):
+    """Create a bare remote repo, add it as origin, verify ls-remote detection works."""
+    # Create a bare repo to act as the remote
+    bare_path = tmp_path / "bare_remote.git"
+    bare_repo = git.Repo.init(bare_path, bare=True)
+
+    # Create a local repo and push to the bare remote
+    local_path = tmp_path / "local_repo"
+    local_repo = git.Repo.init(local_path)
+
+    Path(local_path / "test.txt").write_text("test")
+    local_repo.index.add(["test.txt"])
+    local_repo.index.commit("initial commit")
+
+    local_repo.create_remote("origin", str(bare_path))
+    local_repo.git.push("--set-upstream", "origin", local_repo.active_branch.name)
+
+    result = git_default_branch(local_repo)
+    assert result == f"origin/{local_repo.active_branch.name}"
+
+    shutil.rmtree(local_path)
+    shutil.rmtree(bare_path)
+
+def test_git_default_branch_custom_remote(tmp_path):
+    """Add a remote with a non-'origin' name, verify the remote parameter selects it."""
+    bare_path = tmp_path / "custom_remote.git"
+    bare_repo = git.Repo.init(bare_path, bare=True)
+
+    local_path = tmp_path / "local_repo"
+    local_repo = git.Repo.init(local_path)
+
+    Path(local_path / "test.txt").write_text("test")
+    local_repo.index.add(["test.txt"])
+    local_repo.index.commit("initial commit")
+
+    local_repo.create_remote("upstream", str(bare_path))
+    local_repo.git.push("--set-upstream", "upstream", local_repo.active_branch.name)
+
+    result = git_default_branch(local_repo, remote="upstream")
+    assert result == f"upstream/{local_repo.active_branch.name}"
+
+    shutil.rmtree(local_path)
+    shutil.rmtree(bare_path)
+
+def test_git_default_branch_undetectable(tmp_path):
+    """Repo with no remotes and no main/master branch; should raise ValueError."""
+    repo_path = tmp_path / "no_default_repo"
+    repo = git.Repo.init(repo_path)
+
+    # Create a commit on a non-standard branch name
+    repo.git.checkout("-b", "develop")
+    Path(repo_path / "test.txt").write_text("test")
+    repo.index.add(["test.txt"])
+    repo.index.commit("initial commit")
+
+    with pytest.raises(ValueError, match="Could not determine the default branch"):
+        git_default_branch(repo)
+
+    shutil.rmtree(repo_path)
+
+def test_git_default_branch_revparse_fallback(tmp_path):
+    """When ls-remote fails but local ref cache exists, rev-parse fallback should work."""
+    # Create a bare repo to act as the remote
+    bare_path = tmp_path / "bare_remote.git"
+    git.Repo.init(bare_path, bare=True)
+
+    # Create a local repo and push to the bare remote
+    local_path = tmp_path / "local_repo"
+    local_repo = git.Repo.init(local_path)
+
+    Path(local_path / "test.txt").write_text("test")
+    local_repo.index.add(["test.txt"])
+    local_repo.index.commit("initial commit")
+
+    active_branch = local_repo.active_branch.name
+    local_repo.create_remote("origin", str(bare_path))
+    local_repo.git.push("--set-upstream", "origin", active_branch)
+
+    # Populate local ref cache for origin/HEAD
+    local_repo.git.remote("set-head", "origin", "--auto")
+
+    # Replace remote URL with an invalid path so ls-remote will fail
+    local_repo.git.remote("set-url", "origin", "/nonexistent/path")
+
+    result = git_default_branch(local_repo)
+    assert result == f"origin/{active_branch}"
+
+    shutil.rmtree(local_path)
+    shutil.rmtree(bare_path)
+
+
+# Tests for git_remote
+
+def test_git_remote_no_remotes(test_repository):
+    """Repo with no remotes; verify empty output."""
+    result = git_remote(test_repository)
+    assert result == ""
+
+def test_git_remote_with_remote(tmp_path):
+    """Repo with a remote configured; verify remote name and URL appear in output."""
+    bare_path = tmp_path / "bare_remote.git"
+    git.Repo.init(bare_path, bare=True)
+
+    local_path = tmp_path / "local_repo"
+    local_repo = git.Repo.init(local_path)
+
+    Path(local_path / "test.txt").write_text("test")
+    local_repo.index.add(["test.txt"])
+    local_repo.index.commit("initial commit")
+
+    local_repo.create_remote("origin", str(bare_path))
+
+    result = git_remote(local_repo)
+    assert "origin" in result
+    assert str(bare_path) in result
+
+    shutil.rmtree(local_path)
+    shutil.rmtree(bare_path)