feat(wren): add dlt DuckDB introspection and project generation

wren/src/wren/context.py

@@ -198,6 +198,119 @@ def convert_mdl_to_project(mdl_json: dict) -> list[ProjectFile]:
     return files
 
 
+def convert_dlt_to_project(
+    duckdb_path: str | Path,
+    *,
+    project_name: str | None = None,
+) -> list[ProjectFile]:
+    """Introspect a dlt DuckDB file and generate Wren v2 project files.
+
+    Args:
+        duckdb_path: Path to .duckdb file produced by dlt.
+        project_name: Project name (defaults to DuckDB filename stem).
+
+    Returns:
+        List of ProjectFile ready for write_project_files().
+    """
+    from datetime import datetime  # noqa: PLC0415
+
+    from wren.dlt_introspect import DltIntrospector  # noqa: PLC0415
+
+    duckdb_path = Path(duckdb_path)
+    project_name = project_name or duckdb_path.stem
+
+    with DltIntrospector(duckdb_path) as introspector:
+        tables, relationships = introspector.introspect()
+
+    # Guard: same table name in multiple schemas would silently overwrite model files
+    seen: dict[str, str] = {}
+    for table in tables:
+        prev_schema = seen.setdefault(table.name, table.schema)
+        if prev_schema != table.schema:
+            raise ValueError(
+                f"Duplicate table name across schemas is ambiguous for project "
+                f"generation: {table.name!r} appears in {prev_schema!r} "
+                f"and {table.schema!r}. Rename one of the tables before importing."
+            )
+
+    files: list[ProjectFile] = []
+
+    # ── wren_project.yml ──────────────────────────────────────
+    project_config: dict[str, Any] = {
+        "schema_version": 2,
+        "name": project_name,
+        "version": "1.0",
+        "catalog": "",
+        "schema": "public",
+        "data_source": "duckdb",
+    }
+    files.append(
+        ProjectFile(
+            relative_path="wren_project.yml",
+            content=yaml.dump(
+                project_config, default_flow_style=False, sort_keys=False
+            ),
+        )
+    )
+
+    # ── Models ────────────────────────────────────────────────
+    for table in tables:
+        model: dict[str, Any] = {
+            "name": table.name,
+            "table_reference": {
+                "catalog": table.catalog,
+                "schema": table.schema,
+                "table": table.name,
+            },
+            "columns": [
+                {
+                    "name": col.name,
+                    "type": col.normalized_type,
+                    "is_calculated": False,
+                    "not_null": not col.is_nullable,
+                    "properties": {},
+                }
+                for col in table.columns
+            ],
+            "cached": False,
+            "properties": {"description": "Imported from dlt pipeline"},
+        }
+        files.append(
+            ProjectFile(
+                relative_path=f"models/{table.name}/metadata.yml",
+                content=yaml.dump(model, default_flow_style=False, sort_keys=False),
+            )
+        )
+
+    # ── Relationships ─────────────────────────────────────────
+    files.append(
+        ProjectFile(
+            relative_path="relationships.yml",
+            content=yaml.dump(
+                {"relationships": relationships},
+                default_flow_style=False,
+                sort_keys=False,
+            ),
+        )
+    )
+
+    # ── Instructions ──────────────────────────────────────────
+    now = datetime.utcnow().isoformat(timespec="seconds")
+    files.append(
+        ProjectFile(
+            relative_path="instructions.md",
+            content=(
+                "# Instructions\n\n"
+                "This project was generated from a dlt DuckDB pipeline.\n"
+                f"Source: {duckdb_path}\n"
+                f"Generated: {now}\n"
+            ),
+        )
+    )
+
+    return files
+
+
 def write_project_files(
     files: list[ProjectFile],
     output_dir: Path,

wren/src/wren/context_cli.py

@@ -31,19 +31,41 @@ def init(
         Optional[str],
         typer.Option("--from-mdl", help="Import from MDL JSON file (camelCase)."),
     ] = None,
+    from_dlt: Annotated[
+        Optional[str],
+        typer.Option("--from-dlt", help="Import from dlt-produced DuckDB file."),
+    ] = None,
+    profile: Annotated[
+        Optional[str],
+        typer.Option(
+            "--profile",
+            help="Create a named DuckDB connection profile (requires --from-dlt).",
+        ),
+    ] = None,
     force: Annotated[
         bool,
         typer.Option("--force", help="Overwrite existing project files."),
     ] = False,
 ) -> None:
     """Initialize a new Wren project.
 
-    Without --from-mdl: scaffolds an empty project structure.
+    Without flags: scaffolds an empty project structure.
     With --from-mdl: imports an existing MDL JSON and produces a complete
     v2 YAML project, ready for `wren context validate/build`.
+    With --from-dlt: introspects a dlt DuckDB file and generates models,
+    relationships, and project config automatically.
     """
     project_path = Path(path).expanduser() if path else Path.cwd()
 
+    if from_mdl and from_dlt:
+        typer.echo(
+            "Error: --from-mdl and --from-dlt cannot be used together.", err=True
+        )
+        raise typer.Exit(1)
+    if profile and not from_dlt:
+        typer.echo("Error: --profile requires --from-dlt.", err=True)
+        raise typer.Exit(1)
+
     if from_mdl:
         # ── Import from MDL JSON ──────────────────────────────
         from wren.context import (  # noqa: PLC0415
@@ -77,6 +99,67 @@ def init(
         typer.echo(f"  wren context build --path {project_path}")
         return
 
+    if from_dlt:
+        # ── Import from dlt DuckDB ────────────────────────────
+        from wren.context import (  # noqa: PLC0415
+            convert_dlt_to_project,
+            write_project_files,
+        )
+
+        duckdb_path = Path(from_dlt).expanduser()
+        if not duckdb_path.exists():
+            typer.echo(f"Error: {duckdb_path} not found.", err=True)
+            raise typer.Exit(1)
+
+        try:
+            files = convert_dlt_to_project(duckdb_path)
+        except Exception as e:
+            typer.echo(f"Error reading DuckDB file: {e}", err=True)
+            raise typer.Exit(1)
+
+        try:
+            write_project_files(files, project_path, force=force)
+        except SystemExit as e:
+            typer.echo(str(e), err=True)
+            raise typer.Exit(1)
+
+        # Count models and relationships from generated files
+        model_count = sum(
+            1
+            for f in files
+            if f.relative_path.startswith("models/")
+            and f.relative_path.endswith("/metadata.yml")
+        )
+        rel_count = 0
+        for f in files:
+            if f.relative_path == "relationships.yml":
+                import yaml as _yaml  # noqa: PLC0415
+
+                data = _yaml.safe_load(f.content) or {}
+                rel_count = len(data.get("relationships", []))
+                break
+
+        typer.echo(f"Imported dlt DuckDB to YAML project at {project_path}/")
+        typer.echo(f"  {model_count} models, {rel_count} relationships")
+
+        if profile:
+            from wren.profile import add_profile  # noqa: PLC0415
+
+            add_profile(
+                profile,
+                {
+                    "datasource": "duckdb",
+                    "url": str(duckdb_path.resolve()),
+                },
+                activate=True,
+            )
+            typer.echo(f"  Profile '{profile}' created and activated.")
+
+        typer.echo("\nNext steps:")
+        typer.echo(f"  wren context validate --path {project_path}")
+        typer.echo(f"  wren context build --path {project_path}")
+        return
+
     # ── Scaffold empty project (existing behavior) ────────────
     project_file = project_path / "wren_project.yml"
     if project_file.exists() and not force: