release: cut 0.2.0 baseline

cross_eval/worktree.py

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+"""Git worktree lifecycle management for agentic mode."""
+from __future__ import annotations
+
+import logging
+import shutil
+import subprocess
+from datetime import datetime
+from pathlib import Path
+
+logger = logging.getLogger(__name__)
+
+
+class WorktreeError(RuntimeError):
+    """Error during worktree operations."""
+
+
+def make_branch_name(preset_name: str) -> str:
+    """Generate a branch name for agentic results."""
+    ts = datetime.now().strftime("%Y%m%d_%H%M%S")
+    return f"cross-eval/{preset_name}_{ts}"
+
+
+def create_worktree(base_cwd: Path, work_dir: Path, branch_name: str) -> Path:
+    """Create a git worktree on a new branch from HEAD.
+
+    1. Create branch from HEAD
+    2. Create worktree checked out to that branch
+
+    The branch lives in the original repo, so it survives worktree removal.
+    """
+    work_dir = work_dir.resolve()
+    if work_dir.exists():
+        shutil.rmtree(work_dir)
+
+    # Create the branch at HEAD
+    try:
+        subprocess.run(
+            ["git", "branch", branch_name, "HEAD"],
+            cwd=base_cwd,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+    except subprocess.CalledProcessError as e:
+        raise WorktreeError(
+            f"Failed to create branch '{branch_name}': {e.stderr.strip()}"
+        ) from e
+
+    # Create worktree on that branch
+    try:
+        subprocess.run(
+            ["git", "worktree", "add", str(work_dir), branch_name],
+            cwd=base_cwd,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+    except subprocess.CalledProcessError as e:
+        # Clean up the branch if worktree creation fails
+        subprocess.run(
+            ["git", "branch", "-D", branch_name],
+            cwd=base_cwd,
+            capture_output=True,
+        )
+        raise WorktreeError(
+            f"Failed to create worktree at {work_dir}: {e.stderr.strip()}"
+        ) from e
+
+    logger.debug("Created worktree on branch '%s': %s", branch_name, work_dir)
+    return work_dir
+
+
+def capture_diff(worktree_path: Path) -> str:
+    """Capture all changes made in the worktree as a unified diff.
+
+    Includes both tracked modifications and new untracked files.
+    """
+    subprocess.run(
+        ["git", "add", "-A"],
+        cwd=worktree_path,
+        capture_output=True,
+        check=True,
+    )
+
+    result = subprocess.run(
+        ["git", "diff", "--cached", "HEAD"],
+        cwd=worktree_path,
+        capture_output=True,
+        text=True,
+    )
+    return result.stdout.strip()
+
+
+def commit_worktree(worktree_path: Path, message: str) -> bool:
+    """Stage and commit all changes in the worktree.
+
+    Returns True if a commit was made, False if nothing to commit.
+    """
+    subprocess.run(
+        ["git", "add", "-A"],
+        cwd=worktree_path,
+        capture_output=True,
+        check=True,
+    )
+
+    result = subprocess.run(
+        ["git", "commit", "-m", message],
+        cwd=worktree_path,
+        capture_output=True,
+        text=True,
+    )
+    # exit code 1 = nothing to commit
+    return result.returncode == 0
+
+
+def remove_worktree(base_cwd: Path, work_dir: Path) -> None:
+    """Remove a git worktree (branch is preserved in the original repo)."""
+    work_dir = work_dir.resolve()
+    try:
+        subprocess.run(
+            ["git", "worktree", "remove", "--force", str(work_dir)],
+            cwd=base_cwd,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+    except subprocess.CalledProcessError:
+        if work_dir.exists():
+            shutil.rmtree(work_dir, ignore_errors=True)
+        subprocess.run(
+            ["git", "worktree", "prune"],
+            cwd=base_cwd,
+            capture_output=True,
+        )
+    logger.debug("Removed worktree: %s (branch preserved)", work_dir)