diff --git a/plugins/anime-companion/hooks/register.tsx b/plugins/anime-companion/hooks/register.tsx
index da79fb4..3c135d3 100644
--- a/plugins/anime-companion/hooks/register.tsx
+++ b/plugins/anime-companion/hooks/register.tsx
@@ -1,4 +1,15 @@
 import type { Register } from 'claude-code'
 
-// 骨架：載入後尚無 hook。人格卡注入與強度見 W7、W8（議題 #8、#9）。
-export const register: Register = () => {}
+import { resolveConfig } from './config'
+import { buildRules, SECTION_ID } from './rules'
+
+// 依強度與稱呼把規則段落加到系統提示最後；人格卡與檢索見 W5～W7。
+export const register: Register = (on, options) => {
+  const config = resolveConfig(options)
+  on('prompt.compose', async ($, e, next) => {
+    const result = await next(e)
+    const text = buildRules(config)
+    if (text === null) return result
+    return { sections: [...result.sections, { id: SECTION_ID, text, scope: 'session' }] }
+  })
+}
diff --git a/plugins/anime-companion/hooks/rules.test.ts b/plugins/anime-companion/hooks/rules.test.ts
new file mode 100644
index 0000000..1e51c72
--- /dev/null
+++ b/plugins/anime-companion/hooks/rules.test.ts
@@ -0,0 +1,71 @@
+import { describe, expect, test } from 'claude-code/testing'
+
+import { resolveConfig } from './config'
+import { buildRules, SECTION_ID } from './rules'
+
+const cfg = (o: Record<string, unknown> = {}) => resolveConfig({ defaultCharacter: 'sao-asuna', ...o })
+
+describe('buildRules', () => {
+  test('強度 0 與未選角色不注入', () => {
+    expect(buildRules(cfg({ intensity: '0' }))).toBeNull()
+    expect(buildRules(resolveConfig({}))).toBeNull()
+  })
+
+  test('強度 1 只換稱呼與句尾，沒有氣泡與旁白', () => {
+    const t = buildRules(cfg({ intensity: '1' }))!
+    expect(t).toContain('只換稱呼與句尾')
+    expect(t).not.toContain('前後各一個氣泡')
+    expect(t).not.toContain('最前面再加一行動作旁白')
+  })
+
+  test('強度 2 前後各一個氣泡，無旁白', () => {
+    const t = buildRules(cfg())!
+    expect(t).toContain('前後各一個氣泡')
+    expect(t).toContain('最多一兩句')
+    expect(t).toContain('不加動作旁白')
+  })
+
+  test('強度 3 加動作旁白', () => {
+    const t = buildRules(cfg({ intensity: '3' }))!
+    expect(t).toContain('前後各一個氣泡')
+    expect(t).toContain('最前面再加一行動作旁白')
+    expect(t).not.toContain('不加動作旁白')
+  })
+
+  test('稱呼依角色，設定可覆寫', () => {
+    expect(buildRules(cfg())!).toContain('「桐人」')
+    expect(buildRules(cfg(), 'sao-suguha')!).toContain('「哥哥」')
+    expect(buildRules(cfg({ address: '阿桐' }))!).toContain('「阿桐」')
+  })
+
+  test('各強度都保留安全規則：先用一句清楚的話，需確認時省略收尾氣泡', () => {
+    for (const intensity of ['1', '2', '3']) {
+      const t = buildRules(cfg({ intensity }))!
+      expect(t).toContain('第一句用中性、清楚的話')
+      expect(t).toContain('不加收尾的對話氣泡')
+    }
+  })
+
+  test('角色語氣不進程式碼、commit 與檔案內容', () => {
+    expect(buildRules(cfg())!).toContain('程式碼、commit 訊息與檔案內容保持中性')
+  })
+})
+
+describe('prompt.compose hook', () => {
+  const input = { model: 'm', promptModel: 'm', surfaces: [], tools: [], outputStyle: null, traits: [] }
+  const base = { sections: [{ id: 'intro', text: 'x', scope: 'shared' as const }] }
+
+  test('在原有段落後加入規則段落', { options: { defaultCharacter: 'sao-asuna', intensity: '2' } }, async ($, on) => {
+    on('prompt.compose', ($, e, next) => base)
+    const r = await $.prompt.compose(input)
+    expect(r.sections.at(-1)?.id).toBe(SECTION_ID)
+    expect(r.sections.at(-1)?.scope).toBe('session')
+    expect(r.sections[0]?.id).toBe('intro')
+  })
+
+  test('強度 0 不加段落', { options: { defaultCharacter: 'sao-asuna', intensity: '0' } }, async ($, on) => {
+    on('prompt.compose', ($, e, next) => base)
+    const r = await $.prompt.compose(input)
+    expect(r.sections.some(s => s.id === SECTION_ID)).toBe(false)
+  })
+})
diff --git a/plugins/anime-companion/hooks/rules.ts b/plugins/anime-companion/hooks/rules.ts
new file mode 100644
index 0000000..c521fcc
--- /dev/null
+++ b/plugins/anime-companion/hooks/rules.ts
@@ -0,0 +1,49 @@
+import { CHARACTERS, type CharacterCode } from './characters'
+import { addressFor, type Config, type Intensity } from './config'
+
+export const SECTION_ID = 'anime-companion:rules'
+
+// 任何強度（含 3）都適用：先把該說的事用一句清楚的話說完，再加角色語氣。
+const SAFETY = [
+  '錯誤、風險與需要使用者確認的事，第一句用中性、清楚的話直接說完（不帶角色語氣、不被旁白蓋過），之後才可加角色語氣。',
+  '危險操作需要確認時，不加收尾的對話氣泡與角色語氣的收尾，只留清楚的問句。',
+]
+
+const SCOPE =
+  '角色語氣只套在對使用者說的話；程式碼、commit 訊息與檔案內容保持中性，不得出現角色口吻。'
+
+function levelRules(name: string, intensity: 1 | 2 | 3): string[] {
+  switch (intensity) {
+    case 1:
+      return ['只換稱呼與句尾語氣；不加口癖、吐槽、對話氣泡或動作旁白。']
+    case 2:
+      return [
+        `加入口癖與簡短吐槽，每則回覆最多一兩句角色化的話。`,
+        `角色化的話放進對話氣泡（引用區塊，標示角色名，如「> **${name}**：…」），內容前後各一個氣泡，正文放在兩個氣泡之間。`,
+        '不加動作旁白，不做常駐的狀態列。',
+      ]
+    case 3:
+      return [
+        '完整演出角色：口癖、吐槽、情緒都可充分表現。',
+        `角色化的話放進對話氣泡（引用區塊，標示角色名，如「> **${name}**：…」），內容前後各一個氣泡，正文放在兩個氣泡之間。`,
+        '最前面再加一行動作旁白（斜體，如「*動作描寫*」）。',
+        '不做常駐的狀態列。',
+      ]
+  }
+}
+
+// 依強度與稱呼組成注入系統提示的規則段落；強度 0 或未選角色時回傳 null（不注入）。
+export function buildRules(config: Config, character: CharacterCode | null = config.character): string | null {
+  if (character === null || config.intensity === 0) return null
+  const { name } = CHARACTERS[character]
+  const intensity = config.intensity as Exclude<Intensity, 0>
+  return [
+    `你現在以《刀劍神域》的「${name}」的個性與語氣與使用者對話，同時照常協助使用者做事。`,
+    `稱呼使用者為「${addressFor(config, character)}」。`,
+    SCOPE,
+    ...levelRules(name, intensity),
+    ...SAFETY,
+  ]
+    .map(line => `- ${line}`)
+    .join('\n')
+}