fix(git): normalize git_log schema across filtered and unfiltered branches

src/git/src/mcp_server_git/server.py

@@ -157,45 +157,27 @@ def git_reset(repo: git.Repo) -> str:
     return "All staged changes reset"
 
 def git_log(repo: git.Repo, max_count: int = 10, start_timestamp: Optional[str] = None, end_timestamp: Optional[str] = None) -> list[str]:
-    if start_timestamp or end_timestamp:
-        # Defense in depth: reject timestamps starting with '-' to prevent flag injection
-        if start_timestamp and start_timestamp.startswith("-"):
-            raise ValueError(f"Invalid start_timestamp: '{start_timestamp}' - cannot start with '-'")
-        if end_timestamp and end_timestamp.startswith("-"):
-            raise ValueError(f"Invalid end_timestamp: '{end_timestamp}' - cannot start with '-'")
-        # Use git log command with date filtering
-        args = []
-        if start_timestamp:
-            args.extend(['--since', start_timestamp])
-        if end_timestamp:
-            args.extend(['--until', end_timestamp])
-        args.extend(['--format=%H%n%an%n%ad%n%s%n'])
-
-        log_output = repo.git.log(*args).split('\n')
-
-        log = []
-        # Process commits in groups of 4 (hash, author, date, message)
-        for i in range(0, len(log_output), 4):
-            if i + 3 < len(log_output) and len(log) < max_count:
-                log.append(
-                    f"Commit: {log_output[i]}\n"
-                    f"Author: {log_output[i+1]}\n"
-                    f"Date: {log_output[i+2]}\n"
-                    f"Message: {log_output[i+3]}\n"
-                )
-        return log
-    else:
-        # Use existing logic for simple log without date filtering
-        commits = list(repo.iter_commits(max_count=max_count))
-        log = []
-        for commit in commits:
-            log.append(
-                f"Commit: {commit.hexsha!r}\n"
-                f"Author: {commit.author!r}\n"
-                f"Date: {commit.authored_datetime}\n"
-                f"Message: {commit.message!r}\n"
-            )
-        return log
+    # Defense in depth: reject timestamps starting with '-' to prevent flag injection
+    if start_timestamp and start_timestamp.startswith("-"):
+        raise ValueError(f"Invalid start_timestamp: '{start_timestamp}' - cannot start with '-'")
+    if end_timestamp and end_timestamp.startswith("-"):
+        raise ValueError(f"Invalid end_timestamp: '{end_timestamp}' - cannot start with '-'")
+
+    rev_kwargs: dict[str, str] = {}
+    if start_timestamp:
+        rev_kwargs["since"] = start_timestamp
+    if end_timestamp:
+        rev_kwargs["until"] = end_timestamp
+
+    log = []
+    for commit in repo.iter_commits(max_count=max_count, **rev_kwargs):
+        log.append(
+            f"Commit: {commit.hexsha}\n"
+            f"Author: {commit.author}\n"
+            f"Date: {commit.authored_datetime}\n"
+            f"Message: {commit.message}\n"
+        )
+    return log
 
 def git_create_branch(repo: git.Repo, branch_name: str, base_branch: str | None = None) -> str:
     # Defense in depth: reject names starting with '-' to prevent flag injection

src/git/tests/test_server.py

@@ -234,6 +234,28 @@ def test_git_log_default(test_repository):
     assert len(result) >= 1
     assert "initial commit" in result[0]
 
+
+def test_git_log_schema_matches_across_filter_branches(test_repository):
+    """git_log emits the same string schema whether or not timestamp filters are supplied."""
+    for i in range(2):
+        file_path = Path(test_repository.working_dir) / f"schema_test_{i}.txt"
+        file_path.write_text(f"content {i}")
+        test_repository.index.add([f"schema_test_{i}.txt"])
+        test_repository.index.commit(f"schema commit {i}")
+
+    unfiltered = git_log(test_repository, max_count=1)
+    filtered = git_log(test_repository, max_count=1, start_timestamp="1970-01-01")
+
+    assert len(unfiltered) == 1
+    assert len(filtered) == 1
+    # Same keys, same order — parsers that split on "\n" and ":" must not care which branch produced the entry.
+    assert [line.split(":", 1)[0] for line in unfiltered[0].splitlines()] == \
+           [line.split(":", 1)[0] for line in filtered[0].splitlines()]
+    # And no repr() artefacts (leading quotes, angle brackets) that used to appear only in the unfiltered branch.
+    for entry in (unfiltered[0], filtered[0]):
+        commit_line = entry.splitlines()[0]
+        assert not commit_line.startswith("Commit: '"), f"Commit hash should not be repr-quoted: {commit_line!r}"
+
 def test_git_create_branch(test_repository):
     result = git_create_branch(test_repository, "new-feature-branch")