feat: expand sudoku analysis and interoperability

tests/solver/variantGenerator.test.ts

@@ -196,6 +196,35 @@ describe("variant generator", () => {
     expect(generated.puzzle.rules).not.toMatch(/Kropki|negative/i);
   });
 
+  it("mines deterministically for a requested practice technique", () => {
+    const options = {
+      variant: "classic",
+      size: 9,
+      seed: "mine-practice",
+      targetDifficulty: "hard",
+      requiredTechnique: "naked-pair",
+      maxTechniqueAttempts: 6,
+      maxChecks: 72,
+    } as const;
+    const generated = generateVariant(options);
+    expect(generated.requestedTechnique).toBe("naked-pair");
+    expect(generated.generationAttempts).toBe(4);
+    expect(generated.difficulty.techniqueCounts["naked-pair"]).toBeGreaterThan(
+      0,
+    );
+    expect(generateVariant(options)).toEqual(generated);
+  });
+
+  it("keeps Killer-cage practice tied to the Killer generator", () => {
+    expect(() =>
+      generateVariant({
+        variant: "classic",
+        size: 4,
+        requiredTechnique: "killer-cage",
+      }),
+    ).toThrow(/requires the Killer generator/i);
+  });
+
   it("keeps the public variant ID type exhaustive", () => {
     const ids: GeneratorVariant[] = GENERATOR_VARIANTS.map(({ id }) => id);
     expect(new Set(ids).size).toBe(GENERATOR_VARIANTS.length);