fix: ensure procedural guardian names are unique across floors

- Modified generateGuardianName() in guardian-encounters.ts to add a cycleOffset (floor/50) that shifts prefix selection for the same elements at different 100-floor ranges
- For multi-element names, also shift the title by cycleOffset to further reduce collision chance
- Added regression test guardian-names-unique.test.ts with 7 test cases covering:
  * Previously colliding floors (170/370 crystal, 200/230 exotic convergence, 210/240 astral convergence)
  * All static guardian floors (10-240) uniqueness
  * All procedural guardian floors (250-490) uniqueness
  * Full range (10-490) uniqueness
  * Determinism check
  * Title format validation

Fixes #376

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

@@ -0,0 +1,82 @@
+import { describe, it, expect } from 'vitest';
+import { generateGuardianName } from '../data/guardian-encounters';
+import { getProceduralGuardian } from '../data/guardian-procedural';
+import { getGuardianForFloor } from '../data/guardian-encounters';
+
+describe('guardian name uniqueness', () => {
+  it('generateGuardianName produces different names for same element at different 100-floor cycles', () => {
+    // These floors previously collided: same element, same prefix, same title
+    const name170 = generateGuardianName(['crystal'], 170);
+    const name370 = generateGuardianName(['crystal'], 370);
+    expect(name170).not.toBe(name370);
+  });
+
+  it('generateGuardianName produces different names for multi-element guardians at different cycles', () => {
+    // Floors 200/230 share elements [crystal, stellar, void]
+    const name200 = generateGuardianName(['crystal', 'stellar', 'void'], 200);
+    const name230 = generateGuardianName(['crystal', 'stellar', 'void'], 230);
+    expect(name200).not.toBe(name230);
+
+    // Floors 210/240 share elements [soul, time, plasma]
+    const name210 = generateGuardianName(['soul', 'time', 'plasma'], 210);
+    const name240 = generateGuardianName(['soul', 'time', 'plasma'], 240);
+    expect(name210).not.toBe(name240);
+  });
+
+  it('all static guardian floors (10-240) produce unique names', () => {
+    const names = new Map<string, number>();
+    for (let floor = 10; floor <= 240; floor += 10) {
+      const g = getGuardianForFloor(floor);
+      if (g) {
+        const existing = names.get(g.name);
+        expect(existing).toBeUndefined(
+          `Duplicate name "${g.name}" at floors ${existing} and ${floor}`,
+        );
+        names.set(g.name, floor);
+      }
+    }
+  });
+
+  it('all procedural guardian floors (250-490) produce unique names', () => {
+    const names = new Map<string, number>();
+    for (let floor = 250; floor <= 490; floor += 10) {
+      const g = getProceduralGuardian(floor);
+      if (g) {
+        const existing = names.get(g.name);
+        expect(existing).toBeUndefined(
+          `Duplicate name "${g.name}" at floors ${existing} and ${floor}`,
+        );
+        names.set(g.name, floor);
+      }
+    }
+  });
+
+  it('all guardian floors (10-490) produce unique names', () => {
+    const names = new Map<string, number>();
+    for (let floor = 10; floor <= 490; floor += 10) {
+      const g = getGuardianForFloor(floor);
+      if (g) {
+        const existing = names.get(g.name);
+        expect(existing).toBeUndefined(
+          `Duplicate name "${g.name}" at floors ${existing} and ${floor}`,
+        );
+        names.set(g.name, floor);
+      }
+    }
+  });
+
+  it('generateGuardianName is deterministic (same inputs always produce same output)', () => {
+    const name1 = generateGuardianName(['fire', 'water'], 250);
+    const name2 = generateGuardianName(['fire', 'water'], 250);
+    expect(name1).toBe(name2);
+
+    const name3 = generateGuardianName(['crystal'], 170);
+    const name4 = generateGuardianName(['crystal'], 170);
+    expect(name3).toBe(name4);
+  });
+
+  it('generateGuardianName includes a title', () => {
+    const name = generateGuardianName(['crystal'], 170);
+    expect(name).toMatch(/ the (Warden|Keeper|Lord|Titan|Sovereign|Guardian|Sentinel|Champion|Overlord|Archon)$/);
+  });
+});

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

@@ -46,11 +46,17 @@ const GUARDIAN_TITLES: string[] = [
 ];
 
 export function generateGuardianName(elements: string[], floor: number = 0): string {
+  // Use a cycle offset to ensure the same elements at different 100-floor ranges
+  // produce different names. Without this, floors 170/370/570 etc. with the same
+  // element(s) would produce identical names because both prefix and title cycle.
+  const cycleOffset = Math.floor(floor / 50);
   const parts = elements.map((el, i) => {
     const prefixes = GUARDIAN_PREFIXES[el] || ['Unknown'];
-    return prefixes[(floor + i) % prefixes.length];
+    return prefixes[(floor + i + cycleOffset) % prefixes.length];
   });
-  const title = GUARDIAN_TITLES[Math.floor(floor / 10) % GUARDIAN_TITLES.length];
+  const titleIndex = Math.floor(floor / 10) % GUARDIAN_TITLES.length;
+  // For multi-element names, also shift the title to reduce collision chance
+  const title = GUARDIAN_TITLES[(titleIndex + (elements.length > 1 ? cycleOffset : 0)) % GUARDIAN_TITLES.length];
   return `${parts.join('-')} the ${title}`;
 }