fix(git): stop reporting staged files when nothing was staged

src/git/src/mcp_server_git/server.py

@@ -42,7 +42,7 @@ class GitCommit(BaseModel):
 
 class GitAdd(BaseModel):
     repo_path: str
-    files: list[str]
+    files: list[str] = Field(..., min_length=1)
 
 class GitReset(BaseModel):
     repo_path: str
@@ -125,11 +125,29 @@ def git_diff(repo: git.Repo, target: str, context_lines: int = DEFAULT_CONTEXT_L
     repo.rev_parse(target)  # Validates target is a real git ref, throws BadName if not
     return repo.git.diff(f"--unified={context_lines}", target)
 
+def _staged_paths(repo: git.Repo) -> list[str]:
+    """Paths the index currently holds as changes against HEAD."""
+    if not repo.head.is_valid():
+        # Unborn branch: everything in the index is staged for the first commit.
+        return [str(path) for path, _stage in repo.index.entries]
+    # A rename or delete leaves one side of the diff unset, so take whichever
+    # path the entry does carry and drop any entry with neither.
+    return [
+        path
+        for diff in repo.index.diff(repo.head.commit)
+        if (path := diff.a_path or diff.b_path) is not None
+    ]
+
 def git_commit(repo: git.Repo, message: str) -> str:
     commit = repo.index.commit(message)
     return f"Changes committed successfully with hash {commit.hexsha}"
 
 def git_add(repo: git.Repo, files: list[str]) -> str:
+    if not files:
+        raise ValueError(
+            "No files provided to stage. Pass one or more paths, "
+            "or ['.'] to stage everything."
+        )
     if files == ["."]:
         repo.git.add(".")
     else:
@@ -150,6 +168,15 @@ def git_add(repo: git.Repo, files: list[str]) -> str:
                 )
         # Use '--' to prevent files starting with '-' from being interpreted as options
         repo.git.add("--", *files)
+
+    # `git add` exits 0 when it stages nothing -- an empty pathspec, or '.' on a
+    # tree with no changes -- so the outcome has to be read back from the index
+    # rather than assumed from the exit status.
+    if not _staged_paths(repo):
+        return (
+            "No files staged: the given paths matched no changes. "
+            "git_status shows what is modified or untracked."
+        )
     return "Files staged successfully"
 
 def git_reset(repo: git.Repo) -> str:

src/git/tests/test_server.py

@@ -20,6 +20,7 @@
 )
 import shutil
 import unittest.mock as mock
+from pydantic import ValidationError
 
 @pytest.fixture
 def test_repository(tmp_path: Path):
@@ -111,6 +112,28 @@ def test_git_add_specific_files(test_repository):
     assert "file2.txt" not in staged_files
     assert result == "Files staged successfully"
 
+def test_git_add_reports_when_nothing_was_staged(test_repository):
+    """`git add` exits 0 when it stages nothing, so the old unconditional
+    "Files staged successfully" claimed work on an unchanged tree."""
+    assert not test_repository.is_dirty(untracked_files=True)
+
+    result = git_add(test_repository, ["."])
+
+    assert result != "Files staged successfully"
+    assert "No files staged" in result
+    assert not test_repository.index.diff(test_repository.head.commit)
+
+def test_git_add_rejects_an_empty_file_list(test_repository):
+    """`git add --` with no pathspec is a no-op that exits 0."""
+    with pytest.raises(ValueError, match="No files provided to stage"):
+        git_add(test_repository, [])
+
+def test_git_add_schema_rejects_an_empty_file_list():
+    from mcp_server_git.server import GitAdd
+
+    with pytest.raises(ValidationError):
+        GitAdd(repo_path=".", files=[])
+
 def test_git_add_rejects_path_traversal(test_repository):
     # Security invariant (CVE-2026-27735): a relative path escaping the
     # repository must never be staged. Accept rejection from either the