Python project detection falls back to `pip install -e .` for uv projects when uv.lock is gitignored

[basnijholt]

Bug

agent-cli dev new falls back to pip install -e . (generic Python detection) for projects that use uv when uv.lock is gitignored and pyproject.toml doesn't contain the literal string "uv".

Reproducer

Any Python project using uv where:

1. uv.lock is in .gitignore (common for libraries)
2. pyproject.toml uses a different build backend (e.g., hatchling) and has no [tool.uv] section

# Setup: a minimal uv project with gitignored lockfile
mkdir /tmp/test-uv-project && cd /tmp/test-uv-project
git init
cat > pyproject.toml << 'TOML'
[project]
name = "example"
version = "0.1.0"
requires-python = ">=3.12"
dependencies = ["rich>=13.0.0"]

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"
TOML
echo "uv.lock" >> .gitignore
uv sync  # creates uv.lock locally but it's gitignored
git add -A && git commit -m "init"

# Now create a worktree — uv.lock won't exist there
agent-cli dev new test-branch -a
# Output:
# → Detected Python project        ← should say "Python project with uv"
# → Running: pip install -e .       ← should run "uv sync --all-extras"
# Warning: Setup failed: pip: command not found

Real-world example: basnijholt/matrix-cli — uses uv with hatchling backend, uv.lock is gitignored, pyproject.toml contains no "uv" substring.

Root Cause

In agent_cli/dev/project.py, the detect_project_type() function checks for uv at lines 151-159:

# Python with uv
if (path / "uv.lock").exists() or (
    (path / "pyproject.toml").exists() and "uv" in (path / "pyproject.toml").read_text()
):
    return ProjectType(
        name="python-uv",
        setup_commands=["uv sync --all-extras"],
        description="Python project with uv",
    )

When uv.lock is gitignored, the worktree doesn't have it. And when pyproject.toml doesn't happen to contain the substring "uv" (no [tool.uv] section, no uv-related deps), the detection falls through to the generic Python handler at lines 192-198 which runs pip install -e ..

Suggested Fix

Add uv CLI detection as a fallback — if uv is on PATH and a pyproject.toml exists, prefer uv sync over pip install -e .:

# In the generic Python fallback:
if (path / "pyproject.toml").exists():
    # Prefer uv if available
    if shutil.which("uv"):
        return ProjectType(
            name="python-uv",
            setup_commands=["uv sync --all-extras"],
            description="Python project with uv",
        )
    return ProjectType(
        name="python",
        setup_commands=["pip install -e ."],
        description="Python project",
    )

Or alternatively, check for .python-version file (commonly created by uv init), or detect uv in the build-system requires.

Environment

• agent-cli version: latest
• OS: Linux
• Python: 3.12 (managed by uv, no system pip)