diff --git a/src/components/dice-tray.js b/src/components/dice-tray.js
index 141ff22..f080334 100644
--- a/src/components/dice-tray.js
+++ b/src/components/dice-tray.js
@@ -11,6 +11,7 @@ export class DiceTray extends HTMLElement {
     this._systemId = 'year-zero';
     this.rng = Math.random;
     this.last = null;
+    this.params = {};
   }
   get sides() { return this._sides; }
   set sides(v) { this._sides = Number(v); this.render(); }
@@ -24,7 +25,7 @@ export class DiceTray extends HTMLElement {
   roll() {
     const { results, total } = rollPool([{ sides: this._sides, count: this._count }], this.rng);
     const pack = getRulePack(this._systemId);
-    const verdict = pack ? pack.interpret(results) : null;
+    const verdict = pack ? pack.interpret(results, this.params) : null;
     this.last = { results, total, verdict };
     this.render();
     this.dispatchEvent(new CustomEvent('rolled', { detail: this.last, bubbles: true }));
@@ -36,9 +37,9 @@ export class DiceTray extends HTMLElement {
     const felt = this.last
       ? this.last.results.map((r) => `<span class="rolled" data-value="${r.value}">${r.value}</span>`).join('')
       : '<span class="hint">Tap Roll</span>';
+    const pack = getRulePack(this._systemId);
     const verdict = this.last?.verdict
-      ? `${this.last.verdict.successes} success${this.last.verdict.successes === 1 ? '' : 'es'}` +
-        (this.last.verdict.ones ? ` · ${this.last.verdict.ones} stress` : '')
+      ? (pack && pack.summary ? pack.summary(this.last.verdict) : '')
       : '';
 
     this.innerHTML = `
diff --git a/src/dice/rulepacks/index.js b/src/dice/rulepacks/index.js
index 32c6973..8432605 100644
--- a/src/dice/rulepacks/index.js
+++ b/src/dice/rulepacks/index.js
@@ -4,3 +4,6 @@ const packs = new Map([[yearZero.id, yearZero]]);
 
 export function getRulePack(id) { return packs.get(id) || null; }
 export function registerRulePack(pack) { packs.set(pack.id, pack); }
+export function listRulePacks() {
+  return [...packs.values()].map((p) => ({ id: p.id, label: p.label }));
+}
diff --git a/src/dice/rulepacks/year-zero.js b/src/dice/rulepacks/year-zero.js
index 246a085..3c9e5fd 100644
--- a/src/dice/rulepacks/year-zero.js
+++ b/src/dice/rulepacks/year-zero.js
@@ -1,7 +1,8 @@
 export const yearZero = {
   id: 'year-zero',
   label: 'Year-Zero',
-  interpret(results) {
+  params: [],
+  interpret(results, params = {}) {
     let successes = 0, ones = 0;
     for (const r of results) {
       if (r.value >= 10) successes += 2;
@@ -10,4 +11,8 @@ export const yearZero = {
     }
     return { successes, ones, canPush: true, isCritical: successes >= 2 };
   },
+  summary(v) {
+    const base = `${v.successes} success${v.successes === 1 ? '' : 'es'}`;
+    return v.ones ? `${base} · ${v.ones} stress` : base;
+  },
 };
diff --git a/tests/dice/rulepacks-registry.test.js b/tests/dice/rulepacks-registry.test.js
new file mode 100644
index 0000000..f84adc8
--- /dev/null
+++ b/tests/dice/rulepacks-registry.test.js
@@ -0,0 +1,9 @@
+import { describe, it, expect } from 'vitest';
+import { getRulePack, listRulePacks } from '../../src/dice/rulepacks/index.js';
+
+describe('rule-pack registry', () => {
+  it('lists registered packs as {id,label}', () => {
+    const packs = listRulePacks();
+    expect(packs.some((p) => p.id === 'year-zero' && typeof p.label === 'string')).toBe(true);
+  });
+});
diff --git a/tests/dice/year-zero.test.js b/tests/dice/year-zero.test.js
index 7d0971a..9c5b2e7 100644
--- a/tests/dice/year-zero.test.js
+++ b/tests/dice/year-zero.test.js
@@ -24,3 +24,15 @@ describe('year-zero rule-pack', () => {
     expect(getRulePack('x')).toBe(custom);
   });
 });
+
+describe('year-zero contract v2', () => {
+  it('exposes an empty params list and a summary string', () => {
+    expect(yearZero.params).toEqual([]);
+    expect(yearZero.summary({ successes: 2, ones: 1 })).toBe('2 successes · 1 stress');
+    expect(yearZero.summary({ successes: 1, ones: 0 })).toBe('1 success');
+  });
+  it('interpret ignores a params argument', () => {
+    const v = yearZero.interpret([{ sides: 8, value: 8 }], { anything: true });
+    expect(v.successes).toBe(1);
+  });
+});