refactor: eliminate duplicated code patterns across command modules

[Copilot]

Five internal refactors to remove ~65 lines of duplicated code across command modules. No public API or CLI behaviour changes.

Changes

• Centralize LOCK_FILE — removed duplicate ".rhiza/template.lock" definitions from status.py and tree.py; both now import from _sync_helpers.py

• Extract _load_lock_or_warn(target) in _sync_helpers.py — eliminates the identical 4-line lock-load-or-warn pattern repeated in status.py and tree.py:

  def _load_lock_or_warn(target: Path) -> TemplateLock | None:
      lock_path = (target / LOCK_FILE).resolve()
      if not lock_path.exists():
          logger.warning("No template.lock found — run `rhiza sync` first")
          return None
      return TemplateLock.from_yaml(lock_path)

• _CONFIG_FILES frozenset in summarise.py — replaces the _get_config_files() function (a constant wrapped in a function) with a module-level frozenset[str]

• _validate_git_host() via StrEnum try/except in init.py — replaces manual _value2member_map_ lookup with idiomatic try/except ValueError on the GitHost() constructor

• Extract _log_list(header, items) in sync.py — replaces three identical logging loops in _load_template_from_project():

  _log_list("Templates", template.templates)
  _log_list("Include paths", template.include)
  _log_list("Exclude paths", template.exclude)

Original prompt

Overview

Refactor the codebase to eliminate duplicated code patterns across several command modules. The goal is to save approximately 65+ lines of code by applying the following 5 changes:

---

1. Centralize the LOCK_FILE constant (~8 lines saved)

The string ".rhiza/template.lock" is defined as a module-level constant in three separate files:

• src/rhiza/commands/status.py — LOCK_FILE = ".rhiza/template.lock"
• src/rhiza/commands/tree.py — LOCK_FILE = ".rhiza/template.lock"
• src/rhiza/commands/_sync_helpers.py — LOCK_FILE = ".rhiza/template.lock"

Fix: Keep the definition only in src/rhiza/commands/_sync_helpers.py (it's already there), and import it from there in status.py and tree.py. Remove the duplicate definitions.

---

2. Extract a shared _load_lock_or_warn(target) helper (~20 lines saved)

Both status.py and tree.py repeat the exact same pattern:

lock_path = (target / LOCK_FILE).resolve()
if not lock_path.exists():
    logger.warning("No template.lock found — run `rhiza sync` first")
    return
lock = TemplateLock.from_yaml(lock_path)

Fix: Add the following helper to src/rhiza/commands/_sync_helpers.py:

def _load_lock_or_warn(target: Path) -> "TemplateLock | None":
    """Load the template.lock file, or log a warning and return None if missing."""
    lock_path = (target / LOCK_FILE).resolve()
    if not lock_path.exists():
        logger.warning("No template.lock found — run `rhiza sync` first")
        return None
    return TemplateLock.from_yaml(lock_path)

Then update status.py and tree.py to use this helper instead of repeating the pattern inline.

---

3. Replace _get_config_files() with a module-level constant in summarise.py (~12 lines saved)

In src/rhiza/commands/summarise.py, the function _get_config_files() is just a constant wrapped in a function. Replace it with a module-level frozenset:

_CONFIG_FILES: frozenset[str] = frozenset({
    "Makefile",
    "ruff.toml",
    "pytest.ini",
    ".editorconfig",
    ".gitignore",
    ".pre-commit-config.yaml",
    "renovate.json",
    ".python-version",
})

Update all call sites of _get_config_files() in summarise.py to use _CONFIG_FILES directly.

---

4. Simplify _validate_git_host() in init.py using StrEnum (~10 lines saved)

In src/rhiza/commands/init.py, the function _validate_git_host() manually checks GitHost._value2member_map_. Since GitHost is a StrEnum, use a try/except instead:

def _validate_git_host(git_host: str | None) -> GitHost | None:
    """Validate git_host parameter.

    Args:
        git_host: Git hosting platform.

    Returns:
        Validated GitHost enum value or None.

    Raises:
        ValueError: If git_host is invalid.
    """
    if git_host is None:
        return None
    try:
        return GitHost(git_host.lower())
    except ValueError:
        logger.error(f"Invalid git-host: {git_host}. Must be 'github' or 'gitlab'")
        raise

---

5. Extract a _log_list() helper in sync.py (~15 lines saved)

In src/rhiza/commands/sync.py, the function _load_template_from_project() repeats the same logging pattern three times. Extract a helper:

def _log_list(header: str, items: list[str]) -> None:
    """Log a labelled list of items, if non-empty."""
    if items:
        logger.info(f"{header}:")
        for item in items:
            logger.info(f"  - {item}")

Then replace the three repeated blocks with:

_log_list("Templates", template.templates)
_log_list("Include paths", template.include)
_log_list("Exclude paths", template.exclude)

---

Requirements

• All existing tests must continue to pass.
• Do not change any public API or CLI behaviour — this is purely internal refactoring.
• The changes should be applied across the files listed above.
• Imports should be updated wherever the centralized constant or new helpers are used.

This pull request was created from Copilot chat.

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