Do not mandate global git config

hooks/pre_gen_project.py

@@ -1,9 +1,35 @@
 #!/bin/env python3
+import sys
 from subprocess import run
 
-# Check if git user.name and user.email are configured --> fail early if it's not set
-run(["git", "config", "user.name"], check=True)
-run(["git", "config", "user.email"], check=True)
+
+def git_config_get(key: str) -> str | None:
+    """Return the value of a git config key, or an empty string if it is not set."""
+    result = run(["git", "config", key], capture_output=True, text=True)
+    return result.stdout.strip() if result.returncode == 0 else None
+
 
 # use 'main' as default branch irrespective of git configuration
 run(["git", "init", "--initial-branch=main", "."], check=True)
+
+# Resolve the author identity for the initial commit.
+# We do *not* mandate a global git config: some users configure git per-repository only.
+# Prefer an existing git config (global or system) and fall back to the values the user
+# entered in cookiecutter.
+name = git_config_get("user.name") or "{{ cookiecutter.author_full_name }}".strip()
+email = git_config_get("user.email") or "{{ cookiecutter.author_email }}".strip()
+
+if not name or not email:
+    sys.exit(
+        "ERROR: could not determine an author name/email for the initial commit.\n"
+        "Either configure git (`git config --global user.name ...` and "
+        "`git config --global user.email ...`) or provide the author name/email "
+        "when prompted by the template."
+    )
+
+# Set the identity at the repo level only when it is not already resolvable from existing
+# git config, so we never clobber the user's real git identity.
+if not git_config_get("user.name"):
+    run(["git", "config", "user.name", name], check=True)
+if not git_config_get("user.email"):
+    run(["git", "config", "user.email", email], check=True)

scripts/tests/test_build.py

@@ -1,6 +1,8 @@
 from __future__ import annotations
 
+import os
 import re
+import subprocess
 from pathlib import Path
 from typing import TYPE_CHECKING
 
@@ -55,3 +57,33 @@ def test_build(tmp_path: Path, params: Mapping[str, Any], path: Path | str, patt
         assert pattern.search(path.read_text())
 
     assert not list(proj_dir.rglob("DELETE-ME"))
+
+
+def test_build_without_global_git_config(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    """Generation must succeed without a global/system git identity (see issue #389).
+
+    Users who configure git per-repository only have no global ``user.name``/``user.email``.
+    In that case the hooks should fall back to the cookiecutter ``author_full_name``/
+    ``author_email`` answers so the initial commit still succeeds.
+    """
+    # Neutralize any global/system git config so no ambient git identity is available.
+    monkeypatch.setenv("GIT_CONFIG_GLOBAL", os.devnull)
+    monkeypatch.setenv("GIT_CONFIG_SYSTEM", os.devnull)
+
+    cookiecutter(
+        str(HERE.parent.parent),
+        output_dir=tmp_path,
+        no_input=True,
+        extra_context={"author_full_name": "Jane Doe", "author_email": "jane@example.com"},
+    )
+    proj_dir = tmp_path / "project-name"
+    assert proj_dir.is_dir()
+
+    # The initial commit must exist and be authored by the cookiecutter answers.
+    author = subprocess.run(
+        ["/usr/bin/git", "-C", str(proj_dir), "log", "-1", "--format=%an <%ae>"],
+        capture_output=True,
+        text=True,
+        check=True,
+    ).stdout.strip()
+    assert author == "Jane Doe <jane@example.com>"