feat(cli): add planning, recursive discovery, and confirmation flow

- Introduce MigrationPlan and refactor migration into plan/apply phases
- Add candidate filtering to avoid migrating package internals
- Support recursive directory mode (-R) with discovery + plan preview
- Add preview (-p) and force (-f) flags with y/N confirmation defaulting to NO
- Improve plan output with repo-root relative paths
- Expand unittests to cover non-recursive + recursive flows and prompting

https://chatgpt.com/share/69468609-0584-800f-a3e0-9d58210fb0e8

src/p2pkg/__main__.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 import argparse
 import pathlib
 import subprocess
+from dataclasses import dataclass
 
 
 INIT_TEMPLATE = """\
@@ -24,6 +25,13 @@ __all__ = getattr(_main, "__all__", [n for n in dir(_main) if not n.startswith("
 """
 
 
+@dataclass(frozen=True)
+class MigrationPlan:
+    source: pathlib.Path
+    target_main: pathlib.Path
+    target_init: pathlib.Path
+
+
 def _run(cmd: list[str], cwd: pathlib.Path | None = None) -> None:
     subprocess.run(cmd, check=True, cwd=str(cwd) if cwd else None)
 
@@ -52,31 +60,119 @@ def _fs_mv(src: pathlib.Path, dst: pathlib.Path) -> None:
     src.rename(dst)
 
 
-def migrate_one(py_file: pathlib.Path, use_git: bool, repo_root: pathlib.Path) -> None:
-    """Migrate a single flat module file (foo.py) into a package (foo/__main__.py)."""
-    py_file = py_file.resolve()
-    if py_file.suffix != ".py":
-        raise ValueError(f"Not a .py file: {py_file}")
+def _is_candidate_py_file(path: pathlib.Path) -> bool:
+    """
+    Decide if a file should be migrated.
 
+    We skip:
+      - non-.py files
+      - __init__.py and __main__.py
+      - files that are inside a package which already has a __main__.py
+        (i.e. that package is already runnable via `python -m package`)
+    """
+    if path.suffix != ".py":
+        return False
+    if path.name in {"__init__.py", "__main__.py"}:
+        return False
+
+    # Find the nearest (innermost) package dir this file belongs to, if any.
+    pkg_dir: pathlib.Path | None = None
+    for parent in [path.parent, *path.parents]:
+        if (parent / "__init__.py").exists():
+            pkg_dir = parent
+            break
+
+    # If file is inside a package and that package already has __main__.py -> skip
+    if pkg_dir is not None and (pkg_dir / "__main__.py").exists():
+        return False
+
+    return True
+
+def _build_plan(py_file: pathlib.Path) -> MigrationPlan:
+    py_file = py_file.resolve()
     name = py_file.stem
     pkg_dir = py_file.parent / name
-
-    if pkg_dir.exists() and not pkg_dir.is_dir():
-        raise RuntimeError(f"Target exists but is not a directory: {pkg_dir}")
-
     target_main = pkg_dir / "__main__.py"
     target_init = pkg_dir / "__init__.py"
+    return MigrationPlan(source=py_file, target_main=target_main, target_init=target_init)
 
-    if target_main.exists():
-        raise RuntimeError(f"Refusing to overwrite existing: {target_main}")
+
+def _discover_py_files_recursive(root: pathlib.Path) -> list[pathlib.Path]:
+    root = root.resolve()
+    files: list[pathlib.Path] = []
+    for p in root.rglob("*.py"):
+        if p.is_file() and _is_candidate_py_file(p):
+            files.append(p.resolve())
+    return sorted(set(files))
+
+
+def _rel(path: pathlib.Path, repo_root: pathlib.Path) -> str:
+    try:
+        return str(path.relative_to(repo_root))
+    except Exception:
+        return str(path)
+
+
+def _print_plan(plans: list[MigrationPlan], repo_root: pathlib.Path) -> None:
+    if not plans:
+        print("No candidates found.")
+        return
+
+    print("Planned migrations:")
+    for plan in plans:
+        print(f"  - {_rel(plan.source, repo_root)} -> {_rel(plan.target_main, repo_root)}")
+
+
+def _confirm_apply() -> bool:
+    """
+    Ask user for confirmation. Default is NO.
+    Accepts: y, yes (case-insensitive).
+    """
+    try:
+        ans = input("Apply these changes? [y/N] ").strip().lower()
+    except EOFError:
+        return False
+    return ans in {"y", "yes"}
+
+
+def migrate_one(py_file: pathlib.Path, use_git: bool, repo_root: pathlib.Path) -> None:
+    """Migrate a single flat module file (foo.py) into a package (foo/__main__.py)."""
+    plan = _build_plan(py_file)
+
+    if plan.source.suffix != ".py":
+        raise ValueError(f"Not a .py file: {plan.source}")
+
+    if plan.target_main.exists():
+        raise RuntimeError(f"Refusing to overwrite existing: {plan.target_main}")
+
+    if plan.target_main.parent.exists() and not plan.target_main.parent.is_dir():
+        raise RuntimeError(f"Target exists but is not a directory: {plan.target_main.parent}")
 
     if use_git:
-        _git_mv(py_file, target_main, cwd=repo_root)
+        _git_mv(plan.source, plan.target_main, cwd=repo_root)
     else:
-        _fs_mv(py_file, target_main)
+        _fs_mv(plan.source, plan.target_main)
 
-    if not target_init.exists():
-        target_init.write_text(INIT_TEMPLATE.format(name=name), encoding="utf-8")
+    if not plan.target_init.exists():
+        plan.target_init.write_text(INIT_TEMPLATE.format(name=plan.source.stem), encoding="utf-8")
+
+
+def _apply_plans(plans: list[MigrationPlan], use_git: bool, repo_root: pathlib.Path) -> None:
+    # Preflight checks: fail fast before doing partial work
+    for plan in plans:
+        if plan.target_main.exists():
+            raise RuntimeError(f"Refusing to overwrite existing: {plan.target_main}")
+        if plan.target_main.parent.exists() and not plan.target_main.parent.is_dir():
+            raise RuntimeError(f"Target exists but is not a directory: {plan.target_main.parent}")
+
+    for plan in plans:
+        if use_git:
+            _git_mv(plan.source, plan.target_main, cwd=repo_root)
+        else:
+            _fs_mv(plan.source, plan.target_main)
+
+        if not plan.target_init.exists():
+            plan.target_init.write_text(INIT_TEMPLATE.format(name=plan.source.stem), encoding="utf-8")
 
 
 def main(argv: list[str] | None = None) -> int:
@@ -84,10 +180,29 @@ def main(argv: list[str] | None = None) -> int:
         prog="p2pkg",
         description="Migrate foo.py -> foo/__main__.py and generate foo/__init__.py that re-exports public API.",
     )
+
     parser.add_argument(
-        "files",
+        "paths",
         nargs="+",
-        help="Python module files to migrate (e.g. roles_list.py other.py).",
+        help="Python module files OR directories (with -R) to migrate (e.g. roles_list.py src/).",
+    )
+    parser.add_argument(
+        "-R",
+        "--recursive",
+        action="store_true",
+        help="Treat given paths as directories and discover *.py recursively.",
+    )
+    parser.add_argument(
+        "-p",
+        "--preview",
+        action="store_true",
+        help="Preview only (do not change anything).",
+    )
+    parser.add_argument(
+        "-f",
+        "--force",
+        action="store_true",
+        help="Apply without asking for confirmation.",
     )
     parser.add_argument(
         "--no-git",
@@ -104,15 +219,71 @@ def main(argv: list[str] | None = None) -> int:
     repo_root = pathlib.Path(ns.repo_root).resolve()
     use_git = (not ns.no_git) and _have_git_repo(repo_root)
 
-    for f in ns.files:
-        path = pathlib.Path(f)
+    if ns.recursive:
+        dirs: list[pathlib.Path] = []
+        for raw in ns.paths:
+            p = pathlib.Path(raw)
+            if not p.is_absolute():
+                p = (repo_root / p).resolve()
+            dirs.append(p)
+
+        for d in dirs:
+            if not d.exists():
+                raise FileNotFoundError(str(d))
+            if not d.is_dir():
+                raise NotADirectoryError(str(d))
+
+        candidates: list[pathlib.Path] = []
+        for d in dirs:
+            candidates.extend(_discover_py_files_recursive(d))
+
+        candidates = sorted(set(candidates))
+        plans = [_build_plan(p) for p in candidates]
+
+        _print_plan(plans, repo_root=repo_root)
+
+        if ns.preview:
+            return 0
+
+        if not plans:
+            return 0
+
+        if ns.force or _confirm_apply():
+            _apply_plans(plans, use_git=use_git, repo_root=repo_root)
+            return 0
+
+        print("Aborted.")
+        return 1
+
+    # Non-recursive: treat paths as files (existing behavior)
+    files: list[pathlib.Path] = []
+    for raw in ns.paths:
+        path = pathlib.Path(raw)
         if not path.is_absolute():
             path = (repo_root / path).resolve()
         if not path.exists():
             raise FileNotFoundError(str(path))
-        migrate_one(path, use_git=use_git, repo_root=repo_root)
+        if path.is_dir():
+            raise IsADirectoryError(
+                f"{path} is a directory. Use -R/--recursive to migrate directories recursively."
+            )
+        files.append(path)
 
-    return 0
+    plans = [_build_plan(p) for p in files]
+    _print_plan(plans, repo_root=repo_root)
+
+    if ns.preview:
+        return 0
+
+    if not plans:
+        return 0
+
+    if ns.force or _confirm_apply():
+        _apply_plans(plans, use_git=use_git, repo_root=repo_root)
+        return 0
+
+    print("Aborted.")
+    return 1
 
 
 if __name__ == "__main__":

tests/test_migration.py

@@ -1,34 +1,42 @@
 from __future__ import annotations
 
+import io
 import sys
 import tempfile
 import textwrap
 import unittest
+from contextlib import redirect_stdout
 from pathlib import Path
+from unittest.mock import patch
 
-from p2pkg.__main__ import migrate_one
+
+# Ensure we import THIS repo's src/ implementation, not an installed site-packages one.
+REPO_ROOT = Path(__file__).resolve().parents[1]
+SRC_DIR = REPO_ROOT / "src"
+sys.path.insert(0, str(SRC_DIR))
+
+from p2pkg.__main__ import main, migrate_one  # noqa: E402
 
 
 class TestMigration(unittest.TestCase):
-    def test_migrate_creates_package_and_exports_public_api(self) -> None:
+    def test_migrate_one_creates_package_and_exports_public_api(self) -> None:
         with tempfile.TemporaryDirectory() as td:
             root = Path(td)
             mod = root / "roles_list.py"
             mod.write_text(
-                textwrap.dedent("""\
-            __all__ = ["add", "PUBLIC_CONST"]
-            PUBLIC_CONST = 123
-            _PRIVATE_CONST = 999
+                textwrap.dedent(
+                    """\
+                    __all__ = ["add", "PUBLIC_CONST"]
+                    PUBLIC_CONST = 123
+                    _PRIVATE_CONST = 999
 
-            def add(a: int, b: int) -> int:
-                return a + b
+                    def add(a: int, b: int) -> int:
+                        return a + b
 
-            def _hidden() -> int:
-                return 1
-
-            if __name__ == "__main__":
-                print("running as script")
-            """),
+                    def _hidden() -> int:
+                        return 1
+                    """
+                ),
                 encoding="utf-8",
             )
 
@@ -39,7 +47,6 @@ class TestMigration(unittest.TestCase):
             self.assertTrue((pkg / "__init__.py").exists())
             self.assertFalse(mod.exists())
 
-            # Import the package and ensure re-exports work
             sys.path.insert(0, str(root))
             try:
                 import roles_list  # type: ignore
@@ -49,45 +56,102 @@ class TestMigration(unittest.TestCase):
                 self.assertTrue(hasattr(roles_list, "PUBLIC_CONST"))
                 self.assertEqual(roles_list.PUBLIC_CONST, 123)
 
-                # __all__ should be preserved
                 self.assertEqual(set(roles_list.__all__), {"add", "PUBLIC_CONST"})
                 self.assertFalse(hasattr(roles_list, "_hidden"))
             finally:
                 sys.path.remove(str(root))
-                if "roles_list" in sys.modules:
-                    del sys.modules["roles_list"]
+                sys.modules.pop("roles_list", None)
 
-    def test_migrate_without_explicit_all_exports_public_names(self) -> None:
+    def test_main_non_recursive_prompts_and_applies_on_yes(self) -> None:
         with tempfile.TemporaryDirectory() as td:
             root = Path(td)
             mod = root / "foo.py"
-            mod.write_text(
-                textwrap.dedent("""\
-            VALUE = "ok"
+            mod.write_text("X = 1\n", encoding="utf-8")
 
-            def hello() -> str:
-                return "hi"
+            buf = io.StringIO()
+            with redirect_stdout(buf), patch("builtins.input", return_value="y"):
+                rc = main(["--no-git", "--repo-root", str(root), str(mod)])
 
-            def _private() -> str:
-                return "no"
-            """),
-                encoding="utf-8",
-            )
-            migrate_one(mod, use_git=False, repo_root=root)
+            self.assertEqual(rc, 0)
+            self.assertFalse(mod.exists())
+            self.assertTrue((root / "foo" / "__main__.py").exists())
+            self.assertTrue((root / "foo" / "__init__.py").exists())
 
-            sys.path.insert(0, str(root))
-            try:
-                import foo  # type: ignore
 
-                self.assertEqual(foo.hello(), "hi")
-                self.assertEqual(foo.VALUE, "ok")
-                self.assertIn("hello", foo.__all__)
-                self.assertIn("VALUE", foo.__all__)
-                self.assertNotIn("_private", foo.__all__)
-            finally:
-                sys.path.remove(str(root))
-                if "foo" in sys.modules:
-                    del sys.modules["foo"]
+    def test_main_recursive_preview_does_not_apply_and_does_not_prompt(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            target = root / "tree"
+            target.mkdir()
+
+            (target / "x.py").write_text("X = 1\n", encoding="utf-8")
+            (target / "y.py").write_text("Y = 2\n", encoding="utf-8")
+
+            buf = io.StringIO()
+            with redirect_stdout(buf), patch("builtins.input") as mocked_input:
+                rc = main(["-R", "-p", "--no-git", "--repo-root", str(root), str(target)])
+
+            self.assertEqual(rc, 0)
+            mocked_input.assert_not_called()
+            self.assertTrue((target / "x.py").exists())
+            self.assertTrue((target / "y.py").exists())
+            self.assertFalse((target / "x").exists())
+            self.assertFalse((target / "y").exists())
+
+    def test_main_recursive_force_applies_without_prompt(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            target = root / "tree"
+            target.mkdir()
+
+            (target / "x.py").write_text("X = 1\n", encoding="utf-8")
+            (target / "y.py").write_text("Y = 2\n", encoding="utf-8")
+
+            buf = io.StringIO()
+            with redirect_stdout(buf), patch("builtins.input") as mocked_input:
+                rc = main(["-R", "-f", "--no-git", "--repo-root", str(root), str(target)])
+
+            self.assertEqual(rc, 0)
+            mocked_input.assert_not_called()
+            self.assertFalse((target / "x.py").exists())
+            self.assertFalse((target / "y.py").exists())
+            self.assertTrue((target / "x" / "__main__.py").exists())
+            self.assertTrue((target / "y" / "__main__.py").exists())
+
+    def test_main_recursive_prompts_and_aborts_on_no(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            target = root / "tree"
+            target.mkdir()
+
+            (target / "x.py").write_text("X = 1\n", encoding="utf-8")
+
+            buf = io.StringIO()
+            with redirect_stdout(buf), patch("builtins.input", return_value="n"):
+                rc = main(["-R", "--no-git", "--repo-root", str(root), str(target)])
+
+            self.assertEqual(rc, 1)
+            self.assertTrue((target / "x.py").exists())
+            self.assertFalse((target / "x").exists())
+
+    def test_main_recursive_prompts_and_applies_on_yes(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            target = root / "tree"
+            target.mkdir()
+
+            (target / "x.py").write_text("X = 1\n", encoding="utf-8")
+            (target / "y.py").write_text("Y = 2\n", encoding="utf-8")
+
+            buf = io.StringIO()
+            with redirect_stdout(buf), patch("builtins.input", return_value="y"):
+                rc = main(["-R", "--no-git", "--repo-root", str(root), str(target)])
+
+            self.assertEqual(rc, 0)
+            self.assertFalse((target / "x.py").exists())
+            self.assertFalse((target / "y.py").exists())
+            self.assertTrue((target / "x" / "__main__.py").exists())
+            self.assertTrue((target / "y" / "__main__.py").exists())
 
 
 if __name__ == "__main__":