# ============================================================================
# classifier_tool.py — PLACEHOLDER for Pattern Confirmation (Step 3)
# ============================================================================
#
# Pure tool stub. Will eventually wrap training.train_classifier to validate
# the researcher-refined cluster labels from Step 2. Currently returns a
# placeholder dict so the file exists in the expected location for when
# Step 3 gets built.
# ============================================================================


SCHEMA = {
    "name": "train_classifier_on_refined_labels",
    "description": (
        "PLACEHOLDER. Will train a supervised classifier on the "
        "researcher-refined cluster labels from Pattern Refinement "
        "(Step 2) and evaluate on held-out data. Implements Step 3 of "
        "Nelson's framework (selective coding / Pattern Confirmation)."
    ),
    "parameters": {
        "refined_rows": "list[dict] - sentences with researcher-approved labels",
        "test_ratio": "float - fraction of data held out for evaluation",
    },
    "returns": (
        "dict with accuracy, per_class_metrics, confusion_matrix, "
        "classifier_state"
    ),
}


def train_classifier_on_refined_labels(refined_rows, test_ratio=0.2):
    """Placeholder. Raises NotImplementedError until Step 3 is built."""
    raise NotImplementedError(
        "Step 3 (Pattern Confirmation) is not yet implemented. "
        "Blocked on Step 2 (Pattern Refinement) producing refined labels."
    )