Move viz deps to optional extra; install on first ./mfc.sh viz

pyproject.toml: matplotlib, seaborn, h5py, imageio, imageio-ffmpeg,
plotext, textual, textual-plotext, dash, plotly, and tqdm moved from
[project.dependencies] to [project.optional-dependencies] viz = [...].
None of these are imported by any toolchain command other than viz.

viz.py: _ensure_viz_deps() runs at the top of viz() before any viz
imports. It checks for matplotlib as a sentinel; if absent, installs
the local toolchain[viz] extra via uv (or pip fallback) using the same
UV_LINK_MODE=copy strategy as bootstrap/python.sh. On first run the
user sees a one-time "Installing viz dependencies..." message; subsequent
runs are instant (sentinel import succeeds immediately).

This means ./mfc.sh build, run, test, etc. no longer pull in ~700 MB
of visualization packages that most HPC users never need.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sbryngelson

toolchain/mfc/viz/viz.py

@@ -5,12 +5,50 @@
 """
 
 import os
+import importlib
+import shutil
+import subprocess
+import sys
 
 from mfc.state import ARG
-from mfc.common import MFCException
+from mfc.common import MFC_ROOT_DIR, MFCException
 from mfc.printer import cons
 
 
+def _ensure_viz_deps() -> None:
+    """Install the [viz] optional extras on first use.
+
+    Checks for matplotlib as the sentinel package.  If it is missing the
+    whole viz extra is assumed to be absent and gets installed via uv (or pip
+    as a fallback) from the local toolchain directory.
+    """
+    try:
+        import matplotlib  # noqa: F401  # pylint: disable=import-outside-toplevel,unused-import
+        return  # already installed
+    except ImportError:
+        pass
+
+    toolchain_path = os.path.join(MFC_ROOT_DIR, "toolchain")
+    cons.print("[bold]Installing viz dependencies[/bold] "
+               "(first run — this may take a minute)...")
+
+    env = {**os.environ, "UV_LINK_MODE": "copy"}
+    if shutil.which("uv"):
+        cmd = ["uv", "pip", "install", f"{toolchain_path}[viz]"]
+    else:
+        cmd = [sys.executable, "-m", "pip", "install", f"{toolchain_path}[viz]"]
+
+    result = subprocess.run(cmd, env=env, check=False)
+    if result.returncode != 0:
+        raise MFCException(
+            "Failed to install viz dependencies. "
+            f"Try manually: pip install '{toolchain_path}[viz]'"
+        )
+
+    importlib.invalidate_caches()
+    cons.print("[bold green]Viz dependencies installed.[/bold green]\n")
+
+
 _CMAP_POPULAR = (
     'viridis, plasma, inferno, magma, turbo, '
     'coolwarm, RdBu_r, bwr, hot, jet, gray, seismic'
@@ -82,6 +120,8 @@ def _parse_steps(step_arg, available_steps):
 
 def viz():  # pylint: disable=too-many-locals,too-many-statements,too-many-branches
     """Main viz command dispatcher."""
+    _ensure_viz_deps()
+
     from .reader import discover_format, discover_timesteps, assemble  # pylint: disable=import-outside-toplevel
     from .renderer import render_1d, render_1d_tiled, render_2d, render_3d_slice, render_mp4  # pylint: disable=import-outside-toplevel
 

toolchain/pyproject.toml

@@ -33,18 +33,6 @@ dependencies = [
     "numpy",
     "pandas",
 
-    # Plotting
-    "seaborn",
-    "matplotlib",
-
-    # Visualization
-    "h5py",
-    "imageio>=2.33",
-    "imageio-ffmpeg>=0.5.0",
-    "plotext>=5.2.0",
-    "textual>=0.47.0",
-    "textual-plotext>=0.2.0",
-
     # Chemistry
     "cantera>=3.1.0",
     #"pyrometheus == 1.0.5",
@@ -53,16 +41,40 @@ dependencies = [
     # Frontier Profiling
     "astunparse==1.6.2",
     "colorlover",
-    "dash>=2.0",
     "pymongo",
     "tabulate",
-    "tqdm",
     "dash-svg",
     "dash-bootstrap-components",
     "kaleido",
     "plotille"
 ]
 
+[project.optional-dependencies]
+viz = [
+    # 2D/3D plotting (renderer, TUI)
+    "matplotlib",
+    "seaborn",
+
+    # Silo-HDF5 reader
+    "h5py",
+
+    # MP4 export
+    "imageio>=2.33",
+    "imageio-ffmpeg>=0.5.0",
+
+    # Terminal UI (--tui)
+    "plotext>=5.2.0",
+    "textual>=0.47.0",
+    "textual-plotext>=0.2.0",
+
+    # Interactive web UI (--interactive)
+    "dash>=2.0",
+    "plotly",
+
+    # Progress bar (PNG/MP4 batch rendering)
+    "tqdm",
+]
+
 [tool.hatch.metadata]
 allow-direct-references = true