feat(cli): add py script type & Python interpreter resolution (#3278) (#3285)

* feat(cli): add `py` script type & Python interpreter resolution (#3278)

Introduce a third script variant alongside `sh`/`ps` as the foundation
for unifying workflow scripts under a single Python implementation.

- Add `"py": "Python"` to `SCRIPT_TYPE_CHOICES`; `VALID_SCRIPT_TYPES`
  consumers (init workflow step, init command, _helpers) pick it up
  automatically since they derive from that mapping.
- Add `IntegrationBase.resolve_python_interpreter()` (project venv →
  `python3` → `python`, falling back to `python3`).
- Prefix the resolved interpreter when `process_template()` expands
  `{SCRIPT}` for the `py` script type so `.py` scripts run portably
  (notably on Windows); thread `project_root` through callers so venv
  preference works.
- Make `install_scripts()` mark copied `.py` files executable too.

Includes positive and negative unit tests for interpreter resolution,
`py` template processing, the new choice, and script installation.

Assisted-by: GitHub Copilot (model: Claude Opus 4.8, autonomous)
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(cli): return repo-relative venv interpreter & correct docstring

Address PR review feedback on #3285:

- `resolve_python_interpreter()` now returns the venv interpreter as a
  path relative to the project root (`.venv/bin/python` /
  `.venv/Scripts/python.exe`) instead of an absolute/joined path, so the
  generated `{SCRIPT}` invocation stays portable and runnable from the
  repo root regardless of where the project lives.
- Update `install_scripts()` docstring to note `.py` scripts are now
  made executable alongside `.sh`.
- Update tests to assert the repo-relative interpreter path.

Assisted-by: GitHub Copilot (model: Claude Opus 4.8, autonomous)
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(cli): fall back to sys.executable for interpreter resolution

When neither python3 nor python is discoverable on PATH (and no project
venv is found), resolve_python_interpreter() now returns the running
interpreter (sys.executable) so the generated {SCRIPT} invocation works
in the current environment, falling back to "python3" only if that is
also unavailable. Update unit tests accordingly.

* fix(cli): quote py interpreter path when it contains whitespace

For the `py` script type, the resolved interpreter may be an absolute
path containing spaces (notably `sys.executable` under Windows
`Program Files`). Quote it when it contains whitespace so the `{SCRIPT}`
invocation isn't split into multiple arguments. Add positive/negative
tests for the quoting behavior.

* test: guard executable-bit assertions from Windows chmod semantics

The Windows CI job failed because `os.chmod` does not set POSIX
executable bits on Windows, so `install_scripts()` cannot make `.py`/
`.sh` files executable there (nor is it needed — the interpreter is
invoked explicitly). Split the install_scripts test so file-copy
behavior is still verified cross-platform, and skip the executable-bit
assertions on win32 (matching the repo's existing pattern).

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/specify_cli/_agent_config.py

@@ -17,4 +17,8 @@ AGENT_CONFIG: dict[str, dict[str, Any]] = _build_agent_config()
 
 DEFAULT_INIT_INTEGRATION = "copilot"
 
-SCRIPT_TYPE_CHOICES: dict[str, str] = {"sh": "POSIX Shell (bash/zsh)", "ps": "PowerShell"}
+SCRIPT_TYPE_CHOICES: dict[str, str] = {
+    "sh": "POSIX Shell (bash/zsh)",
+    "ps": "PowerShell",
+    "py": "Python",
+}

src/specify_cli/integrations/base.py

@@ -17,6 +17,7 @@ import os
 import re
 import shlex
 import shutil
+import sys
 from abc import ABC
 from dataclasses import dataclass
 from pathlib import Path
@@ -495,8 +496,8 @@ class IntegrationBase(ABC):
 
         Copies files from this integration's ``scripts/`` directory to
         ``.specify/integrations/<key>/scripts/`` in the project.  Shell
-        scripts are made executable.  All copied files are recorded in
-        *manifest*.
+        (``.sh``) and Python (``.py``) scripts are made executable.  All
+        copied files are recorded in *manifest*.
 
         Returns the list of files created.
         """
@@ -513,7 +514,7 @@ class IntegrationBase(ABC):
                 continue
             dst_script = scripts_dest / src_script.name
             shutil.copy2(src_script, dst_script)
-            if dst_script.suffix == ".sh":
+            if dst_script.suffix in (".sh", ".py"):
                 dst_script.chmod(dst_script.stat().st_mode | 0o111)
             self.record_file_in_manifest(dst_script, project_root, manifest)
             created.append(dst_script)
@@ -538,6 +539,47 @@ class IntegrationBase(ABC):
             content,
         )
 
+    @staticmethod
+    def resolve_python_interpreter(project_root: Path | None = None) -> str:
+        """Resolve a portable Python interpreter command for ``{SCRIPT}``.
+
+        Used to build the invocation string for the ``py`` script type so
+        that ``.py`` workflow scripts run consistently across platforms
+        (notably Windows, where ``.py`` files are not directly executable).
+
+        Resolution order:
+
+        1. A project virtual environment (``.venv``) interpreter, if one
+           exists under *project_root* (POSIX ``bin/python`` or Windows
+           ``Scripts/python.exe``).  The returned path is **relative to the
+           project root** (e.g. ``.venv/bin/python``) so generated
+           ``{SCRIPT}`` invocations stay portable and runnable from the
+           repo root regardless of where the project lives.
+        2. ``python3`` on ``PATH``.
+        3. ``python`` on ``PATH``.
+
+        Falls back to the running interpreter (``sys.executable``) when
+        ``PATH`` resolution fails so the generated command is guaranteed
+        to work in the current environment, and finally to ``"python3"``
+        if even that is unavailable.
+        """
+        if project_root is not None:
+            # (existence check path, repo-root-relative invocation string)
+            venv_candidates = (
+                (project_root / ".venv" / "bin" / "python", ".venv/bin/python"),
+                (
+                    project_root / ".venv" / "Scripts" / "python.exe",
+                    ".venv/Scripts/python.exe",
+                ),
+            )
+            for candidate, relative in venv_candidates:
+                if candidate.exists():
+                    return relative
+        for name in ("python3", "python"):
+            if shutil.which(name):
+                return name
+        return sys.executable or "python3"
+
     @staticmethod
     def process_template(
         content: str,
@@ -545,6 +587,7 @@ class IntegrationBase(ABC):
         script_type: str,
         arg_placeholder: str = "$ARGUMENTS",
         invoke_separator: str = ".",
+        project_root: Path | None = None,
     ) -> str:
         """Process a raw command template into agent-ready content.
 
@@ -578,6 +621,17 @@ class IntegrationBase(ABC):
 
         # 2. Replace {SCRIPT}
         if script_command:
+            # For the Python script type, prefix the resolved interpreter so
+            # the command is portable (``.py`` files are not directly
+            # executable on Windows).
+            if script_type == "py":
+                interpreter = IntegrationBase.resolve_python_interpreter(project_root)
+                # Quote the interpreter if it contains whitespace (e.g. an
+                # absolute ``sys.executable`` path under Windows
+                # ``Program Files``) so it isn't split into multiple args.
+                if any(ch.isspace() for ch in interpreter):
+                    interpreter = f'"{interpreter}"'
+                script_command = f"{interpreter} {script_command}"
             content = content.replace("{SCRIPT}", script_command)
 
         # 3. Strip scripts: section from frontmatter
@@ -784,6 +838,7 @@ class MarkdownIntegration(IntegrationBase):
             raw = src_file.read_text(encoding="utf-8")
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
             )
             dst_name = self.command_filename(src_file.stem)
             dst_file = self.write_file_and_record(
@@ -986,6 +1041,7 @@ class TomlIntegration(IntegrationBase):
             description = self._extract_description(raw)
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
             )
             _, body = self._split_frontmatter(processed)
             toml_content = self._render_toml(description, body)
@@ -1186,6 +1242,7 @@ class YamlIntegration(IntegrationBase):
 
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
             )
             _, body = self._split_frontmatter(processed)
             yaml_content = self._render_yaml(
@@ -1381,6 +1438,7 @@ class SkillsIntegration(IntegrationBase):
             # Process body through the standard template pipeline
             processed_body = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
                 invoke_separator=self.invoke_separator,
             )
             # Strip the processed frontmatter — we rebuild it for skills.

src/specify_cli/integrations/copilot/__init__.py

@@ -370,6 +370,7 @@ class CopilotIntegration(IntegrationBase):
             raw = src_file.read_text(encoding="utf-8")
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
             )
             dst_name = self.command_filename(src_file.stem)
             dst_file = self.write_file_and_record(

src/specify_cli/integrations/forge/__init__.py

@@ -134,6 +134,7 @@ class ForgeIntegration(MarkdownIntegration):
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
                 invoke_separator=self.invoke_separator,
+                project_root=project_root,
             )
 
             # FORGE-SPECIFIC: Ensure any remaining $ARGUMENTS placeholders are

src/specify_cli/integrations/generic/__init__.py

@@ -123,6 +123,7 @@ class GenericIntegration(MarkdownIntegration):
             raw = src_file.read_text(encoding="utf-8")
             processed = self.process_template(
                 raw, self.key, script_type, arg_placeholder,
+                project_root=project_root,
             )
             dst_name = self.command_filename(src_file.stem)
             dst_file = self.write_file_and_record(

src/specify_cli/integrations/hermes/__init__.py

@@ -140,6 +140,7 @@ class HermesIntegration(SkillsIntegration):
                 script_type,
                 arg_placeholder,
                 invoke_separator=self.invoke_separator,
+                project_root=project_root,
             )
             # Strip the processed frontmatter — we rebuild it for skills.
             if processed_body.startswith("---"):

tests/integrations/test_base.py

@@ -1,5 +1,7 @@
 """Tests for IntegrationOption, IntegrationBase, MarkdownIntegration, and primitives."""
 
+import sys
+
 import pytest
 
 from specify_cli.integrations.base import (
@@ -299,3 +301,186 @@ class TestResolveCommandRefs:
         text = "__SPECKIT_COMMAND_V2_PLAN__"
         result = IntegrationBase.resolve_command_refs(text, ".")
         assert result == "/speckit.v2.plan"
+
+
+class TestResolvePythonInterpreter:
+    def test_returns_python_on_path(self, monkeypatch):
+        # Positive: when python3 is on PATH it is preferred over python.
+        def fake_which(name):
+            return f"/usr/bin/{name}" if name in ("python3", "python") else None
+
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", fake_which
+        )
+        assert IntegrationBase.resolve_python_interpreter() == "python3"
+
+    def test_falls_back_to_python_when_no_python3(self, monkeypatch):
+        def fake_which(name):
+            return "/usr/bin/python" if name == "python" else None
+
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", fake_which
+        )
+        assert IntegrationBase.resolve_python_interpreter() == "python"
+
+    def test_falls_back_to_sys_executable_when_nothing_found(self, monkeypatch):
+        # Negative: nothing on PATH and no venv -> the running interpreter
+        # (sys.executable) is used so the command works in this environment.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", lambda name: None
+        )
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.sys.executable", "/opt/py/bin/python"
+        )
+        assert IntegrationBase.resolve_python_interpreter() == "/opt/py/bin/python"
+
+    def test_falls_back_to_python3_when_no_interpreter_at_all(self, monkeypatch):
+        # Negative edge: neither PATH nor sys.executable resolves.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", lambda name: None
+        )
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.sys.executable", ""
+        )
+        assert IntegrationBase.resolve_python_interpreter() == "python3"
+
+    def test_prefers_project_venv_posix(self, monkeypatch, tmp_path):
+        venv_python = tmp_path / ".venv" / "bin" / "python"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("")
+        # Even if python3 is on PATH, the project venv wins. The returned
+        # path is relative to the project root for portability.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which",
+            lambda name: "/usr/bin/python3",
+        )
+        result = IntegrationBase.resolve_python_interpreter(tmp_path)
+        assert result == ".venv/bin/python"
+
+    def test_prefers_project_venv_windows(self, monkeypatch, tmp_path):
+        venv_python = tmp_path / ".venv" / "Scripts" / "python.exe"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("")
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", lambda name: None
+        )
+        result = IntegrationBase.resolve_python_interpreter(tmp_path)
+        assert result == ".venv/Scripts/python.exe"
+
+    def test_ignores_missing_venv(self, monkeypatch, tmp_path):
+        # Negative: no venv directory -> PATH resolution is used instead.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which",
+            lambda name: "/usr/bin/python3" if name == "python3" else None,
+        )
+        assert IntegrationBase.resolve_python_interpreter(tmp_path) == "python3"
+
+
+class TestProcessTemplatePyScriptType:
+    CONTENT = (
+        "---\n"
+        "scripts:\n"
+        "  sh: scripts/bash/check-prerequisites.sh --json\n"
+        "  ps: scripts/powershell/check-prerequisites.ps1 -Json\n"
+        "  py: scripts/python/check-prerequisites.py --json\n"
+        "---\n"
+        "Run {SCRIPT} now."
+    )
+
+    def test_py_prefixes_interpreter(self, monkeypatch):
+        # Positive: py script type prefixes a resolved interpreter and the
+        # script path is rewritten to the .specify location.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which",
+            lambda name: "/usr/bin/python3" if name == "python3" else None,
+        )
+        result = IntegrationBase.process_template(self.CONTENT, "agent", "py")
+        assert "python3 .specify/scripts/python/check-prerequisites.py --json" in result
+        # The scripts: frontmatter block is stripped.
+        assert "scripts:" not in result
+
+    def test_sh_does_not_prefix_interpreter(self):
+        # Negative: non-py script types are never prefixed with an interpreter.
+        result = IntegrationBase.process_template(self.CONTENT, "agent", "sh")
+        assert ".specify/scripts/bash/check-prerequisites.sh --json" in result
+        assert "python" not in result
+
+    def test_py_quotes_interpreter_with_spaces(self, monkeypatch):
+        # An interpreter path containing whitespace (e.g. Windows
+        # ``Program Files``) must be quoted so it isn't split into args.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which", lambda name: None
+        )
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.sys.executable",
+            r"C:\Program Files\Python\python.exe",
+        )
+        result = IntegrationBase.process_template(self.CONTENT, "agent", "py")
+        assert (
+            '"C:\\Program Files\\Python\\python.exe" '
+            ".specify/scripts/python/check-prerequisites.py --json"
+        ) in result
+
+    def test_py_does_not_quote_interpreter_without_spaces(self, monkeypatch):
+        # Negative: a whitespace-free interpreter is left unquoted.
+        monkeypatch.setattr(
+            "specify_cli.integrations.base.shutil.which",
+            lambda name: "/usr/bin/python3" if name == "python3" else None,
+        )
+        result = IntegrationBase.process_template(self.CONTENT, "agent", "py")
+        assert '"' not in result.split("check-prerequisites.py")[0]
+
+    def test_py_uses_project_venv(self, monkeypatch, tmp_path):
+        venv_python = tmp_path / ".venv" / "bin" / "python"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("")
+        result = IntegrationBase.process_template(
+            self.CONTENT, "agent", "py", project_root=tmp_path
+        )
+        assert ".venv/bin/python .specify/scripts/python/check-prerequisites.py" in result
+
+
+class TestInstallScriptsPython:
+    def _make_integration_with_scripts(self, monkeypatch, tmp_path):
+        scripts_src = tmp_path / "bundled_scripts"
+        scripts_src.mkdir()
+        (scripts_src / "common.py").write_text("print('hi')\n")
+        (scripts_src / "common.sh").write_text("echo hi\n")
+        (scripts_src / "notes.txt").write_text("not executable\n")
+        integration = StubIntegration()
+        monkeypatch.setattr(
+            integration, "integration_scripts_dir", lambda: scripts_src
+        )
+        return integration
+
+    def test_copies_all_script_files(self, monkeypatch, tmp_path):
+        # Cross-platform: every bundled file is copied into the project.
+        integration = self._make_integration_with_scripts(monkeypatch, tmp_path)
+        project_root = tmp_path / "proj"
+        project_root.mkdir()
+        manifest = IntegrationManifest("stub", project_root.resolve())
+
+        created = integration.install_scripts(project_root, manifest)
+        names = {p.name for p in created}
+        assert {"common.py", "common.sh", "notes.txt"} == names
+
+    @pytest.mark.skipif(
+        sys.platform == "win32", reason="chmod exec bit not reliable on Windows"
+    )
+    def test_marks_py_and_sh_executable(self, monkeypatch, tmp_path):
+        integration = self._make_integration_with_scripts(monkeypatch, tmp_path)
+        project_root = tmp_path / "proj"
+        project_root.mkdir()
+        manifest = IntegrationManifest("stub", project_root.resolve())
+
+        integration.install_scripts(project_root, manifest)
+
+        dest = project_root / ".specify" / "integrations" / "stub" / "scripts"
+        py_file = dest / "common.py"
+        sh_file = dest / "common.sh"
+        txt_file = dest / "notes.txt"
+        # Positive: .py and .sh are executable.
+        assert py_file.stat().st_mode & 0o111
+        assert sh_file.stat().st_mode & 0o111
+        # Negative: a non-script file is not made executable.
+        assert not (txt_file.stat().st_mode & 0o111)

tests/test_commands_package.py

@@ -24,6 +24,20 @@ def test_agent_config_importable():
     assert "sh" in SCRIPT_TYPE_CHOICES
 
 
+def test_script_type_choices_includes_python():
+    from specify_cli._agent_config import SCRIPT_TYPE_CHOICES
+    assert SCRIPT_TYPE_CHOICES.get("py") == "Python"
+    # The three supported variants are sh, ps, and py.
+    assert {"sh", "ps", "py"} <= set(SCRIPT_TYPE_CHOICES)
+
+
+def test_workflow_init_valid_script_types_includes_python():
+    from specify_cli.workflows.steps.init import VALID_SCRIPT_TYPES
+    assert "py" in VALID_SCRIPT_TYPES
+    # Negative: an unknown variant is not accepted.
+    assert "rb" not in VALID_SCRIPT_TYPES
+
+
 def test_agent_config_re_exported_from_init():
     from specify_cli import AGENT_CONFIG, SCRIPT_TYPE_CHOICES
     assert isinstance(AGENT_CONFIG, dict)