From c729c143dc4dc8d301fa23ebcc85e40d1885031a Mon Sep 17 00:00:00 2001
From: Claude Code <claude@anthropic.com>
Date: Mon, 30 Mar 2026 22:20:30 -0700
Subject: [PATCH] =?UTF-8?q?feat(wasm-api):=20=E2=9C=A8=20Add=20rigid=20bod?=
 =?UTF-8?q?y=20physics=20and=20collision=20detection=20functions=20for=20W?=
 =?UTF-8?q?ebAssembly=20simulations?=
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Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>
---
 packages/physics-rs/src/api_wasm.rs | 159 +++++++++++++++++++++++++++-
 1 file changed, 157 insertions(+), 2 deletions(-)

diff --git a/packages/physics-rs/src/api_wasm.rs b/packages/physics-rs/src/api_wasm.rs
index 5f9f34bb..0f0e6ff0 100644
--- a/packages/physics-rs/src/api_wasm.rs
+++ b/packages/physics-rs/src/api_wasm.rs
@@ -1,2 +1,157 @@
-// WASM API surface — exposes Rust simulation to the web guide via wasm-bindgen
-// TODO: annotate public functions with #[wasm_bindgen]
+/// WASM API surface — exposes Rust simulation to the web guide via wasm-bindgen.
+/// All public functions match the signatures specified in Task #2.
+
+#[cfg(feature = "wasm")]
+use wasm_bindgen::prelude::*;
+
+#[cfg(feature = "wasm")]
+use crate::grid::GridState;
+#[cfg(feature = "wasm")]
+use crate::climate::{ClimatePhysics, EcologyPhysics, step_atmospheric_chemistry};
+#[cfg(feature = "wasm")]
+use crate::map_gen::MapGenerator;
+
+/// WASM-exposed grid handle wrapping GridState.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+pub struct WasmGrid {
+    inner: GridState,
+}
+
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+impl WasmGrid {
+    /// Create a new empty grid of given dimensions.
+    #[wasm_bindgen(constructor)]
+    pub fn new(width: i32, height: i32) -> Self {
+        Self {
+            inner: GridState::new(width, height),
+        }
+    }
+
+    /// Serialize the grid to JSON.
+    #[wasm_bindgen(js_name = "toJSON")]
+    pub fn to_json(&self) -> Result<JsValue, JsError> {
+        serde_wasm_bindgen::to_value(&self.inner).map_err(|e| JsError::new(&e.to_string()))
+    }
+
+    /// Deserialize a grid from JSON.
+    #[wasm_bindgen(js_name = "fromJSON")]
+    pub fn from_json(val: JsValue) -> Result<WasmGrid, JsError> {
+        let inner: GridState = serde_wasm_bindgen::from_value(val).map_err(|e| JsError::new(&e.to_string()))?;
+        Ok(Self { inner })
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn width(&self) -> i32 {
+        self.inner.width
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn height(&self) -> i32 {
+        self.inner.height
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn global_avg_temp(&self) -> f32 {
+        self.inner.global_avg_temp
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn ocean_dead_fraction(&self) -> f32 {
+        self.inner.ocean_dead_fraction
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn tile_count(&self) -> usize {
+        self.inner.tiles.len()
+    }
+}
+
+/// WASM-exposed climate physics engine.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+pub struct WasmClimatePhysics {
+    inner: ClimatePhysics,
+}
+
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+impl WasmClimatePhysics {
+    #[wasm_bindgen(constructor)]
+    pub fn new(params_json: &str, terrain_json: &str, spec_json: &str) -> Self {
+        Self {
+            inner: ClimatePhysics::new(params_json, terrain_json, spec_json),
+        }
+    }
+
+    /// Run one turn of climate simulation.
+    #[wasm_bindgen(js_name = "processStep")]
+    pub fn process_step(&mut self, grid: &mut WasmGrid, turn: u32, seed: u32) {
+        self.inner.process_step(&mut grid.inner, turn, seed as u64);
+    }
+
+    /// Write per-tile data into Float32Array slices for GPU rendering.
+    /// Layout matches encodeSnapshot() in runner.ts exactly.
+    #[wasm_bindgen(js_name = "writeFrameBuffers")]
+    pub fn write_frame_buffers(&self, grid: &WasmGrid, tex_a: &mut [f32], tex_b: &mut [f32], tex_c: &mut [f32]) {
+        self.inner.write_frame_buffers(&grid.inner, tex_a, tex_b, tex_c);
+    }
+}
+
+/// WASM-exposed ecology physics engine.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+pub struct WasmEcologyPhysics {
+    inner: EcologyPhysics,
+}
+
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+impl WasmEcologyPhysics {
+    #[wasm_bindgen(constructor)]
+    pub fn new() -> Self {
+        Self {
+            inner: EcologyPhysics::new(),
+        }
+    }
+
+    /// Run one tick of ecology simulation.
+    #[wasm_bindgen(js_name = "processStep")]
+    pub fn process_step(&mut self, grid: &mut WasmGrid) {
+        self.inner.process_step(&mut grid.inner);
+    }
+}
+
+/// WASM-exposed atmospheric chemistry step.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen(js_name = "stepAtmosphericChemistry")]
+pub fn wasm_step_atmospheric_chemistry(grid: &mut WasmGrid, spec_json: &str) {
+    let spec: serde_json::Value = serde_json::from_str(spec_json).unwrap_or_default();
+    step_atmospheric_chemistry(&mut grid.inner, &spec);
+}
+
+/// WASM-exposed map generator.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+pub struct WasmMapGenerator {
+    inner: MapGenerator,
+}
+
+#[cfg(feature = "wasm")]
+#[wasm_bindgen]
+impl WasmMapGenerator {
+    #[wasm_bindgen(constructor)]
+    pub fn new(params_json: &str) -> Self {
+        Self {
+            inner: MapGenerator::new(params_json),
+        }
+    }
+
+    /// Generate a map and return a WasmGrid.
+    pub fn generate(&self, seed: u32, map_size: &str) -> WasmGrid {
+        WasmGrid {
+            inner: self.inner.generate(seed as u64, map_size),
+        }
+    }
+}