mcp: the probe tool takes at, points whose nearest nodes are probed (#105)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/mcp/src/tests.rs

@@ -224,6 +224,22 @@ fn screenshot_takes_a_camera_orientation() {
     assert_eq!(again, turned);
 }
 
+/// `probe {at}` reads a structural result at the nodes nearest to points (#105); hostile points
+/// are refused without a panic.
+#[test]
+fn probe_takes_points_at() {
+    let mut s = server();
+    ok(&mut s, "execute", json!({"command": "file.sample", "params": {"name": "cantilever"}}));
+    ok(&mut s, "solve", json!({"analysis": "static", "step": "Load"}));
+    let r = ok(&mut s, "probe", json!({"step": "Load", "at": [[0, 0, 0]]}));
+    let node = &r["nodes"][0];
+    assert!(node["xyz"].is_array() && node["distance"].is_number(), "{r}");
+    for at in [json!([[1e308, "x"]]), json!(vec![json!([0, 0, 0]); 20_000])] {
+        let (text, err) = call(&mut s, "probe", json!({"step": "Load", "at": at}));
+        assert!(err && text.len() < 100_000, "{text}");
+    }
+}
+
 #[test]
 fn a_batch_stops_at_the_first_error() {
     let mut s = server();

crates/mcp/src/tools.rs

@@ -251,7 +251,7 @@ pub fn tool_definitions() -> Vec<Value> {
         tool(
             "probe",
             "Probe results",
-            "Stored results at nodes (solve.probe): displacement, reaction, stress and von Mises (static), the shape of \
+            "Stored results at nodes, or at the nodes nearest to points `at` (solve.probe): displacement, reaction, stress and von Mises (static), the shape of \
              mode `mode` (frequency), displacement and velocity in field frame `frame` (explicit) and, with `elements`, \
              explicit element values; for a fluid step, the flow at `points` and the force histories of `forces`.",
             obj(
@@ -259,6 +259,7 @@ pub fn tool_definitions() -> Vec<Value> {
                     "step": string("Solved step"),
                     "nodes": {"type": "array", "items": {"type": "integer"}, "description": "Node labels"},
                     "elements": {"type": "array", "items": {"type": "integer"}, "description": "Element labels (explicit)"},
+                    "at": {"type": "array", "items": {"type": "array"}, "description": "Points [x, y, z]; the nearest nodes are probed (structural steps)"},
                     "points": {"type": "array", "items": {"type": "array"}, "description": "Points [x, y, z] (fluid)"},
                     "forces": {"type": "array", "items": {"type": "string"}, "description": "Walls or faces whose force histories to return (fluid)"},
                     "mode": integer("Mode, from 1 (frequency)"),
@@ -497,7 +498,7 @@ fn dispatch(b: &mut dyn Backend, name: &str, a: &Map<String, Value>) -> Result<V
             b.execute(command, params)
         }
         "show_results" => show_results(b, a),
-        "probe" => b.execute("solve.probe", pick(a, &["step", "nodes", "elements", "points", "forces", "mode", "frame"])),
+        "probe" => b.execute("solve.probe", pick(a, &["step", "nodes", "at", "elements", "points", "forces", "mode", "frame"])),
         "reactions" => b.execute("results.reactions", pick(a, &["step", "sets", "about"])),
         "select" => {
             let p = pick(a, &["filter", "box_mode", "mode", "clear", "geometry", "nodes", "elements", "faces", "at", "box"]);

docs/mcp.md

@@ -102,7 +102,7 @@ software on the computer.
 | `mesh` | `method`, `params?` | Runs the mesher (`tet`: `mesh.tet.generate`; `hex`, `hex_sweep`, `hex_mapped`, `hex_blocks`: the structured hex meshers; `cells`: `mesh.cells`, a partitioned part cell by cell; `mirror`: `mesh.mirror`, a meshed half reflected across a plane; `block`: `mesh.block`; `planar`: `mesh.planar`) and replies with its result, `model.info` and `mesh.quality`. |
 | `solve` | `analysis` (static, frequency, explicit, fluid; heat as it lands), `step?`, `options?` | `solve.<analysis>` with the step and the solver's caps and settings. |
 | `show_results` | `step?`, `field?`, `bands?`, `deformed?`, `scale?`, `mode?`, `frame?`, `time?` | The `results.*` commands its arguments ask for (`deformed: false` draws the undeformed mesh; `scale` is a factor, 0 for the undeformed shape so a sequence from 0 swings the deformation out, or `"auto"`); the reply has the contour range (smallest and largest value and their nodes: `field: "displacement"` gives the largest displacement), modes or frames. |
-| `probe` | `step?`, `nodes?`, `elements?`, `points?`, `forces?`, `mode?`, `frame?` | `solve.probe`: stored results at nodes, elements (explicit) or points (fluid). |
+| `probe` | `step?`, `nodes?`, `at?`, `elements?`, `points?`, `forces?`, `mode?`, `frame?` | `solve.probe`: stored results at nodes, at the nodes nearest to points `at` (structural steps), elements (explicit) or points (fluid). |
 | `reactions` | `step?`, `sets?`, `about?` | `results.reactions`: reaction force and moment per node set and in total. |
 | `screenshot` | `view?`, `camera?`, `source?` (window, model), `width?`, `height?`, `path?` | A PNG image content block and what it shows. Headless: a CPU render framing the model, the geometry, the analysis setup's symbols (boundary conditions, loads, reference points, couplings; `sampled_symbols` lists definitions drawn with a sample) and the results display (deformed shape, contour bands). Bridged: the whole app window drawn offscreen (`ui.capture`, the default) or a model render with the app's camera (`ui.render`). `view` turns the camera to a standard view first; `camera` `{yaw, pitch, distance?}` to any orientation, in degrees (yaw 0 looks along +Y, −45 is the iso view's; pitch is the elevation, clamped to ±90) and model units (`ui.camera`; headless, the picture is framed unless `distance` is given). Give one of the two; the orientation is kept for the next picture, so a sequence of `camera` angles orbits smoothly. |
 | `select` | `filter?`, `box_mode?`, `mode?`, `clear?`, `geometry?`, `nodes?`, `elements?`, `faces?`, `at?`, `box?` | Bridged only: changes the app's viewport selection (`ui.select`; control-protocol.md, Selection) and returns it. Headless it is an error: selection belongs to the window. |