fix: make guardian names deterministic per floor instead of using Math.random()

- generateGuardianName() now takes a floor parameter and uses floor % prefixes.length for deterministic prefix selection
- generateComboGuardianName() now takes a floor parameter and uses (floor + i) % prefixes.length for each element
- getGuardianForFloor() passes floor to generateGuardianName for static guardians with empty names
- getExtendedGuardian() passes floor to generateComboGuardianName for combo guardians
- Removes dependency on Math.random() → names are stable across ticks/refreshes

Fixes #161

docs/circular-deps.txt

@@ -1,4 +1,4 @@
 # Circular Dependencies
-Generated: 2026-05-27T09:16:38.657Z
+Generated: 2026-05-27T09:18:37.387Z
 
 No circular dependencies found. ✅

docs/dependency-graph.json

@@ -1,6 +1,6 @@
 {
   "_meta": {
-    "generated": "2026-05-27T09:16:36.915Z",
+    "generated": "2026-05-27T09:18:35.464Z",
     "description": "Import dependency graph for src/lib/game. Keys are files, values are arrays of files they import.",
     "usage": "To find what a file affects, search for its path in the VALUES. To find what a file depends on, look at its KEY entry."
   },

docs/project-structure.txt

@@ -213,6 +213,7 @@ Mana-Loop/
 │       │   │   ├── floor-utils.test.ts
 │       │   │   ├── floor-utils.upgraded.test.ts
 │       │   │   ├── formatting.test.ts
+│       │   │   ├── guardian-names.test.ts
 │       │   │   ├── mana-utils.test.ts
 │       │   │   ├── pact-utils.test.ts
 │       │   │   ├── regression-fixes.test.ts

src/lib/game/__tests__/guardian-names.test.ts

@@ -0,0 +1,137 @@
+// ─── Guardian Name Determinism Test ───────────────────────────────────────────
+// Regression test for #161: Guardian names must be deterministic per floor.
+// Names derived from Math.random() would change on every call.
+
+import { describe, it, expect } from 'vitest';
+import {
+  generateGuardianName,
+  generateComboGuardianName,
+  getGuardianForFloor,
+  getExtendedGuardian,
+} from '../data/guardian-encounters';
+
+describe('generateGuardianName', () => {
+  it('should return the same name for the same element and floor', () => {
+    const name1 = generateGuardianName('fire', 90);
+    const name2 = generateGuardianName('fire', 90);
+    expect(name1).toBe(name2);
+  });
+
+  it('should return different names for different elements', () => {
+    const nameFire = generateGuardianName('fire', 90);
+    const nameWater = generateGuardianName('water', 90);
+    expect(nameFire).not.toBe(nameWater);
+  });
+
+  it('should return different names for different floors', () => {
+    const name90 = generateGuardianName('fire', 90);
+    const name100 = generateGuardianName('fire', 100);
+    expect(name90).not.toBe(name100);
+  });
+
+  it('should produce non-empty names', () => {
+    const name = generateGuardianName('metal', 90);
+    expect(name).toBeTruthy();
+    expect(name.length).toBeGreaterThan(0);
+  });
+
+  it('should follow the "Prefix the Title" pattern', () => {
+    const name = generateGuardianName('crystal', 120);
+    expect(name).toMatch(/^[\w]+ the [\w]+$/);
+  });
+
+  it('should produce "Unknown the <title>" for unknown element', () => {
+    const name = generateGuardianName('nonexistent', 90);
+    expect(name).toMatch(/^Unknown the [\w]+$/);
+  });
+});
+
+describe('generateComboGuardianName', () => {
+  it('should return the same name for the same elements and floor', () => {
+    const name1 = generateComboGuardianName(['fire', 'water'], 150);
+    const name2 = generateComboGuardianName(['fire', 'water'], 150);
+    expect(name1).toBe(name2);
+  });
+
+  it('should return different names for different floors', () => {
+    const name150 = generateComboGuardianName(['fire', 'water'], 150);
+    const name160 = generateComboGuardianName(['fire', 'water'], 160);
+    expect(name150).not.toBe(name160);
+  });
+
+  it('should combine both element prefixes with hyphen', () => {
+    const name = generateComboGuardianName(['fire', 'water'], 150);
+    expect(name).toMatch(/^[\w]+-[\w]+ the [\w]+$/);
+  });
+});
+
+describe('getGuardianForFloor', () => {
+  it('should return stable names for compound guardians (floors 90-110)', () => {
+    const g90a = getGuardianForFloor(90);
+    const g90b = getGuardianForFloor(90);
+    expect(g90a).not.toBeNull();
+    expect(g90b).not.toBeNull();
+    expect(g90a!.name).toBe(g90b!.name);
+
+    const g100a = getGuardianForFloor(100);
+    const g100b = getGuardianForFloor(100);
+    expect(g100a!.name).toBe(g100b!.name);
+
+    const g110a = getGuardianForFloor(110);
+    const g110b = getGuardianForFloor(110);
+    expect(g110a!.name).toBe(g110b!.name);
+  });
+
+  it('should return stable names for exotic guardians (floors 120-140)', () => {
+    for (const floor of [120, 130, 140]) {
+      const a = getGuardianForFloor(floor);
+      const b = getGuardianForFloor(floor);
+      expect(a).not.toBeNull();
+      expect(a!.name).toBe(b!.name);
+    }
+  });
+
+  it('should preserve existing names for base guardians', () => {
+    const g10 = getGuardianForFloor(10);
+    expect(g10!.name).toBe('Ignis Prime');
+  });
+
+  it('should return different names for different floors', () => {
+    const g90 = getGuardianForFloor(90);
+    const g120 = getGuardianForFloor(120);
+    expect(g90!.name).not.toBe(g120!.name);
+  });
+});
+
+describe('getExtendedGuardian', () => {
+  it('should return stable names for combo guardians (floor 150+)', () => {
+    const a = getExtendedGuardian(150);
+    const b = getExtendedGuardian(150);
+    expect(a).not.toBeNull();
+    expect(b).not.toBeNull();
+    expect(a!.name).toBe(b!.name);
+  });
+
+  it('should return different names for different combo floors', () => {
+    const g150 = getExtendedGuardian(150);
+    const g160 = getExtendedGuardian(160);
+    expect(g150).not.toBeNull();
+    expect(g160).not.toBeNull();
+    expect(g150!.name).not.toBe(g160!.name);
+  });
+
+  it('should return null for non-guardian floors', () => {
+    expect(getExtendedGuardian(151)).toBeNull();
+    expect(getExtendedGuardian(155)).toBeNull();
+  });
+
+  it('should produce unique names across many repeated calls', () => {
+    const names = new Set<string>();
+    for (let i = 0; i < 100; i++) {
+      const g = getGuardianForFloor(90);
+      names.add(g!.name);
+    }
+    // All 100 calls should produce exactly 1 unique name
+    expect(names.size).toBe(1);
+  });
+});

src/lib/game/data/guardian-encounters.ts

@@ -36,19 +36,19 @@ const GUARDIAN_TITLES: string[] = [
   'Guardian', 'Sentinel', 'Champion', 'Overlord', 'Archon',
 ];
 
-export function generateGuardianName(element: string): string {
+export function generateGuardianName(element: string, floor: number = 0): string {
   const prefixes = GUARDIAN_PREFIXES[element] || ['Unknown'];
-  const prefix = prefixes[Math.floor(Math.random() * prefixes.length)];
-  const title = GUARDIAN_TITLES[Math.floor(Math.random() * GUARDIAN_TITLES.length)];
+  const prefix = prefixes[floor % prefixes.length];
+  const title = GUARDIAN_TITLES[Math.floor(floor / 10) % GUARDIAN_TITLES.length];
   return `${prefix} the ${title}`;
 }
 
-export function generateComboGuardianName(elements: string[]): string {
-  const parts = elements.map((el) => {
+export function generateComboGuardianName(elements: string[], floor: number = 0): string {
+  const parts = elements.map((el, i) => {
     const prefixes = GUARDIAN_PREFIXES[el] || ['Unknown'];
-    return prefixes[Math.floor(Math.random() * prefixes.length)];
+    return prefixes[(floor + i) % prefixes.length];
   });
-  const title = GUARDIAN_TITLES[Math.floor(Math.random() * GUARDIAN_TITLES.length)];
+  const title = GUARDIAN_TITLES[Math.floor(floor / 10) % GUARDIAN_TITLES.length];
   return `${parts.join('-')} the ${title}`;
 }
 
@@ -115,7 +115,7 @@ export function getExtendedGuardian(floor: number): GuardianDef | null {
     const g = getComboGuardian(floor);
     if (!g.name) {
       const elements = g.element.split('+');
-      g.name = generateComboGuardianName(elements);
+      g.name = generateComboGuardianName(elements, floor);
     }
     return g;
   }
@@ -129,7 +129,7 @@ export function getExtendedGuardian(floor: number): GuardianDef | null {
 export function getGuardianForFloor(floor: number): GuardianDef | null {
   if (BASE_GUARDIANS[floor]) {
     const g = { ...BASE_GUARDIANS[floor] };
-    if (!g.name) g.name = generateGuardianName(g.element);
+    if (!g.name) g.name = generateGuardianName(g.element, floor);
     return g;
   }
   return getExtendedGuardian(floor);