feat(render): fasthep render graph renders a compile output's graph

CHANGELOG.md

@@ -10,6 +10,12 @@ Add new entries under `## [Unreleased]`, in the category they belong to. At rele
 
 ## [Unreleased]
 
+### Added
+
+- `fasthep render graph <build dir>` renders `graph/graph.d2` of a compile output directory to
+  `graph/graph.svg`. The compile step skips this for large graphs (fasthep-render), and its warning
+  names this command.
+
 ### Changed
 
 - Depends on `fasthep-flow`, `fasthep-curator`, `fasthep-render`, and `fasthep-toolbench[display,http]`

src/fasthep_cli/commands/render.py

@@ -46,3 +46,29 @@ def render_spec_command(
     typer.echo("Render complete")
     typer.echo(f"Status: {outcome.status.value}")
     typer.echo(f"Output: {outcome.output_path}")
+
+
+@render_app.command("graph")
+def render_graph_command(
+    build_dir: Path = typer.Argument(
+        ...,
+        exists=True,
+        file_okay=False,
+        help="Compile output directory (the --outdir of fasthep compile or run).",
+    ),
+) -> None:
+    """Render graph/graph.d2 of a compile output directory to graph/graph.svg.
+
+    The compile step skips this for large graphs because it can take minutes.
+    """
+    try:
+        graph_hooks = import_module("fasthep_render.graph.compile_hooks")
+    except ModuleNotFoundError as exc:
+        msg = "fasthep-render is required for 'fasthep render graph'"
+        raise typer.BadParameter(msg) from exc
+
+    result = graph_hooks.render_compile_graph(build_dir)
+    typer.echo(f"Status: {result['status']}")
+    if result.get("message"):
+        typer.echo(f"Message: {result['message']}")
+    typer.echo(f"Output: {result['output']}")

tests/test_cli_render.py

@@ -4,6 +4,7 @@
 from pathlib import Path
 
 import fasthep_render.api as render_api
+import fasthep_render.graph.compile_hooks as graph_hooks
 import pytest
 import yaml
 from fasthep_render.model import RenderStatus
@@ -190,3 +191,25 @@ def test_render_command_has_no_dispatch_helpers() -> None:
     assert not hasattr(render_command_module, "render_resolved")
     assert not hasattr(render_command_module, "resolve_runtime_registry")
     assert not hasattr(render_command_module, "read_pickle")
+
+
+def test_render_graph_command_renders_the_compile_graph(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    calls: list[tuple[Path, int | None]] = []
+
+    def fake_render_compile_graph(
+        build_root: Path, *, max_bytes: int | None = None
+    ) -> dict[str, str]:
+        calls.append((build_root, max_bytes))
+        return {"status": "rendered", "output": str(build_root / "graph" / "graph.svg")}
+
+    monkeypatch.setattr(graph_hooks, "render_compile_graph", fake_render_compile_graph)
+
+    result = runner.invoke(app, ["render", "graph", str(tmp_path)])
+
+    assert result.exit_code == 0, strip_ansi(result.output)
+    assert calls == [(tmp_path, None)]
+    assert "Status: rendered" in result.output
+    assert str(tmp_path / "graph" / "graph.svg") in result.output