feat(tht): schema columns reader (name/description/type/pk) from catalog

harness/tests/test_schema_columns_cmd.py

@@ -0,0 +1,40 @@
+import json
+from datetime import datetime
+
+from typer.testing import CliRunner
+
+from tht.cli import app  # the root Typer app that mounts schema_app as "schema"
+from tht.mschema.models import ColumnPhysical, PhysicalSchema, TablePhysical
+
+
+def _write_catalog(tmp_path):
+    phys = PhysicalSchema(
+        database="d", schema="s", introspected_at=datetime(2026, 1, 1),
+        tables={
+            "dim_patient": TablePhysical(
+                comment="Anagrafica",
+                columns={
+                    "cod_paz": ColumnPhysical(type="bigint", pk=True, comment="Codice paziente"),
+                    "nome": ColumnPhysical(type="text", comment="Nome"),
+                },
+            )
+        },
+    )
+    out = tmp_path / "artifacts" / "mschema" / "physical.yaml"
+    phys.to_yaml(out)
+    return out
+
+
+def test_schema_columns_json(tmp_path, monkeypatch):
+    _write_catalog(tmp_path)
+    cfg = tmp_path / "workspace.yaml"
+    cfg.write_text(
+        "database: {database: d, schema: s, user: u, password: p, transport: direct}\n"
+        f"paths: {{artifacts: {tmp_path/'artifacts'}, indexes: {tmp_path/'i'}, sessions: {tmp_path/'s'}}}\n"
+    )
+    res = CliRunner().invoke(app, ["schema", "columns", "dim_patient", "--json", "-c", str(cfg)])
+    assert res.exit_code == 0, res.output
+    data = json.loads(res.output)
+    assert data["table"] == "dim_patient"
+    assert data["description"] == "Anagrafica"
+    assert {"name": "cod_paz", "description": "Codice paziente", "type": "bigint", "pk": True} in data["columns"]

harness/tht/cli/schema_cmd.py

@@ -156,3 +156,43 @@ def render_cmd(
         typer.secho(f"OK: scritto {output}", fg=typer.colors.GREEN)
     else:
         typer.echo(out)
+
+
+@schema_app.command("columns")
+def columns_cmd(
+    table: str = typer.Argument(..., help="Nome tabella (chiave in physical.yaml)."),
+    json_out: bool = typer.Option(False, "--json", help="Emetti JSON puro su stdout."),
+    config: Path = CONFIG_OPT,
+) -> None:
+    """Elenca nome/descrizione/tipo/pk delle colonne di una tabella dal catalogo."""
+    import json as _json
+
+    from tht.mschema.models import PhysicalSchema
+
+    cfg = _load_config_or_exit(config)
+    phys_file = physical_path(cfg)
+    if not phys_file.exists():
+        typer.secho(
+            f"ERRORE: {phys_file} non trovato. Esegui prima `tht schema introspect`.",
+            fg=typer.colors.RED, err=True,
+        )
+        raise typer.Exit(code=1)
+    physical = PhysicalSchema.from_yaml(phys_file)
+    tbl = physical.tables.get(table)
+    if tbl is None:
+        typer.secho(f"ERRORE: tabella non nel catalogo: {table}", fg=typer.colors.RED, err=True)
+        raise typer.Exit(code=1)
+    payload = {
+        "table": table,
+        "description": tbl.comment,
+        "columns": [
+            {"name": name, "description": col.comment, "type": col.type, "pk": col.pk}
+            for name, col in tbl.columns.items()
+        ],
+    }
+    if json_out:
+        typer.echo(_json.dumps(payload, ensure_ascii=False))
+        return
+    typer.echo(f"{table}: {tbl.comment}")
+    for c in payload["columns"]:
+        typer.echo(f"  {'*' if c['pk'] else ' '} {c['name']} ({c['type']}) — {c['description']}")