Function derive_skill

openspace/skill_engine/patch.py:181–279

Derive a new skill from one or more existing skills. **Single parent** (``source_dirs`` is one Path): Copies parent directory → applies LLM output. Supports PATCH / DIFF / FULL. **Multiple parents** (``source_dirs`` is a list of Paths): Creates a brand-new directory and applie

(
    source_dirs: Union[Path, List[Path]],
    target_dir: Path,
    content: str,
    patch_type: PatchType = PatchType.AUTO,
)

    )

def derive_skill(
    source_dirs: Union[Path, List[Path]],
    target_dir: Path,
    content: str,
    patch_type: PatchType = PatchType.AUTO,
) -> SkillEditResult:
    """Derive a new skill from one or more existing skills.

    **Single parent** (``source_dirs`` is one Path):
      Copies parent directory → applies LLM output.  Supports PATCH / DIFF / FULL.

    **Multiple parents** (``source_dirs`` is a list of Paths):
      Creates a brand-new directory and applies LLM output as FULL or PATCH
      (DIFF not supported for multi-parent — no single base to search/replace).
      ``content_diff`` is empty for multi-parent (no meaningful single-parent
      diff); ``content_snapshot`` captures the full result for lineage tracking.

    Source directories stay unchanged in both cases.

    Args:
        source_dirs: Parent skill directory (or list for multi-parent merge).
        target_dir: New skill directory (must not exist).
        content: LLM output.
        patch_type: Output format (AUTO to auto-detect).
    """
    # Normalise to list
    if isinstance(source_dirs, Path):
        sources = [source_dirs]
    else:
        sources = list(source_dirs)

    if not sources:
        return SkillEditResult(error="derive_skill requires at least one source directory")
    if target_dir.exists():
        return SkillEditResult(error=f"Target already exists: {target_dir}")

    # Validate all sources
    for sd in sources:
        if not sd.is_dir():
            return SkillEditResult(error=f"Source does not exist: {sd}")
        if not (sd / SKILL_FILENAME).exists():
            return SkillEditResult(error=f"Source SKILL.md not found: {sd / SKILL_FILENAME}")

    first_source = sources[0]
    is_multi_parent = len(sources) > 1

    if is_multi_parent:
        # Multi-parent merge: create new directory, apply content (FULL or PATCH)
        if patch_type == PatchType.AUTO:
            patch_type = detect_patch_type(content)
        if patch_type == PatchType.DIFF:
            # DIFF (SEARCH/REPLACE) is not meaningful for merge — no single base
            patch_type = PatchType.FULL

        try:
            target_dir.mkdir(parents=True, exist_ok=True)
            if patch_type == PatchType.PATCH:
                _apply_multi_file_patch(content, target_dir)