Adding first working version

backend/test/caInitialConditionGenerators.test.ts

@@ -8,8 +8,11 @@ import {
 
 describe('CA initial condition runtimes', () => {
   it('registers the built-in random soup generator', () => {
-    expect(listInitialConditionRuntimes().map((runtime) => runtime.id)).toContain('random-soup')
+    expect(listInitialConditionRuntimes().map((runtime) => runtime.id)).toEqual(
+      expect.arrayContaining(['random-soup', 'naga-markov'])
+    )
     expect(getInitialConditionRuntime('random-soup')?.label).toBe('Random soup')
+    expect(getInitialConditionRuntime('naga-markov')?.label).toBe('Naga Markov chains')
   })
 
   it('generates deterministic cell coordinates for the same seed and density', () => {
@@ -47,6 +50,49 @@ describe('CA initial condition runtimes', () => {
     }).cells).toEqual([[1, 1, 0]])
   })
 
+  it('generates collision-free Naga Markov chains with directional continuity', () => {
+    const generated = generateInitialCondition('naga-markov', {
+      caClass: { dimensions: 3, states: 7 },
+      settings: { simulation: { grid: { size: [12, 12, 12] } } },
+      params: { count: 2, length: 5, sameTypeProbability: 1, seed: 'straight-nagas' }
+    })
+
+    expect(generated.cells).toHaveLength(10)
+    expect(new Set(generated.cells.map(([x, y, z]) => `${x}_${y}_${z}`)).size).toBe(10)
+    expect(generated.generator).toMatchObject({
+      kind: 'naga-markov',
+      count: 2,
+      length: 5,
+      sameTypeProbability: 1,
+      seed: 'straight-nagas',
+      created: 2
+    })
+
+    const occupied = new Set(generated.cells.map(([x, y, z]) => `${x}_${y}_${z}`))
+    for (let start = 0; start < generated.cells.length; start += 5) {
+      for (let index = start; index < start + 4; index += 1) {
+        const [x, y, z, arrow] = generated.cells[index]
+        const [nextX, nextY, nextZ, nextArrow] = generated.cells[index + 1]
+        expect(nextArrow).toBe(arrow)
+        if (arrow === 1) expect([nextX, nextY, nextZ]).toEqual([x + 1, y, z])
+        if (arrow === 2) expect([nextX, nextY, nextZ]).toEqual([x, y + 1, z])
+        if (arrow === 3) expect([nextX, nextY, nextZ]).toEqual([x, y, z + 1])
+        if (arrow === 4) expect([nextX, nextY, nextZ]).toEqual([x - 1, y, z])
+        if (arrow === 5) expect([nextX, nextY, nextZ]).toEqual([x, y - 1, z])
+        if (arrow === 6) expect([nextX, nextY, nextZ]).toEqual([x, y, z - 1])
+      }
+      const [x, y, z, arrow] = generated.cells[start + 4]
+      const terminalTarget =
+        arrow === 1 ? [x + 1, y, z] :
+        arrow === 2 ? [x, y + 1, z] :
+        arrow === 3 ? [x, y, z + 1] :
+        arrow === 4 ? [x - 1, y, z] :
+        arrow === 5 ? [x, y - 1, z] :
+        [x, y, z - 1]
+      expect(occupied.has(terminalTarget.join('_'))).toBe(false)
+    }
+  })
+
   it('rejects duplicate runtime ids and missing implementations', () => {
     expect(() =>
       registerInitialConditionRuntime({