# Demo video

`make.py` regenerates the README's demo, `docs/media/ibeam-analysis.mp4` and
`docs/media/ibeam-analysis.gif`: an agent analyses an I-beam cantilever over MCP while the
desktop app shows each step.

```sh
python3 tools/demo-video/make.py                  # build, run, encode into docs/media
python3 tools/demo-video/make.py --no-build       # with the release binaries already built
python3 tools/demo-video/make.py --frames /tmp/f  # also keep the captured pictures
```

Needs Python 3 (standard library only), a display for the app window (the pictures are drawn
offscreen, so a locked screen is fine) and `ffmpeg` with libx264 on the `PATH` (or `FFMPEG`).
It honours `CARGO_TARGET_DIR`.

What it does:

1. Builds `fieldcraft`, `fieldcraft-cli` and the testkit's `corpus` tool (release).
2. Writes the corpus cantilever I-beam (`tests/corpus/cantilever-i-beam`: 40 x 40 mm, 3 mm
   flanges, a 2 mm web upright, 200 mm long along x) as a `.solidcraft` design to a temporary
   folder with `corpus --part cantilever-i-beam --design`.
3. Starts the app with `--control PORT` and `fieldcraft-cli mcp --connect 127.0.0.1:PORT`, and
   speaks MCP (JSON-RPC over stdio) to it. Every step is an MCP tool call: `open` the design,
   `mesh` (`hex_sweep`, 4 mm), `batch` (steel, a solid section, the root clamp, a kinematic
   coupling of the free end at x = 200 mm to a reference point loaded with 1000 N down, −z), `check_model`, `solve`
   (`static`), and `show_results` for the von Mises contours and the deformed shape, its `scale`
   stepped from 1 to 150 and back. Every picture is the MCP `screenshot` tool with
   `source: window` (the whole window drawn offscreen, `ui.capture`), turned to the `iso` or
   `front` view by its `view` argument.
4. Encodes the pictures at 10 frames per second, each held for its stage, into the MP4 (H.264,
   1280 px) and the GIF (960 px, its own palette), and prints the tip deflection and the peak
   von Mises stress.

The theme is the app's default (dark).

The script checks the solution against beam theory and stops when it is off. Tip deflection:
P L³ / 3 E I = 0.1429 mm in bending plus P L / G A_web = 0.0335 mm in shear, 0.1763 mm; the
solution gives 0.1764 mm (within 3 %). Root bending stress: P L c / I = 45.0 MPa
(I = 88 871 mm⁴); the solution's stress_xx on the top flange, fitted along the beam between one
depth from either end and extrapolated to the root, gives 44.8 MPa (within 2 %). At the root
itself the clamp, which stops the section's Poisson contraction, adds a local peak (62 MPa
stress_xx, 56 MPa von Mises) that beam theory does not have.