feat(ai): zod schema validator + Korean-first prompt

Task 10 of the slice plan. parseAiResponse runs the model JSON
through a zod RawResponseSchema, then enforces slice rules:
- title MUST contain Korean characters; throw otherwise.
- summary normalized to exactly 3 lines (pad with empty when too
  few; collapse trailing lines into line 3 when too many).
- tags filtered to /^[a-z0-9]+(-[a-z0-9]+)*$/ kebab-case and
  capped at 3.
buildPrompt assembles the user-facing prompt with explicit
Korean-output / kebab-tag / no-fence rules (PROMPT_VERSION=1).

Verification: `npx vitest run tests/unit/ai-schema.test.ts`
7 passed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main/ai/prompt.ts

@@ -0,0 +1,22 @@
+export const PROMPT_VERSION = 1;
+
+export function buildPrompt(rawText: string): string {
+  return `You organize raw personal notes into structured metadata.
+
+Input note (raw text, may be fragmented, any language):
+---
+${rawText}
+---
+
+Return a JSON object with EXACTLY these keys:
+- "title": concise title in KOREAN (max 60 chars)
+- "summary": 3-line summary in KOREAN. Each line max 120 chars. Lines separated by "\\n".
+- "tags": array of 0 to 3 tags in lowercase kebab-case (English letters and digits only, e.g., "api-timeout", "weekly-retro"). Empty array if no clear tags.
+
+Rules:
+- title and summary MUST be written in Korean regardless of input language.
+- tags MUST be English kebab-case (for consistency across notes; easier to search/group).
+- Do NOT invent facts not present in the input.
+- Do NOT include markdown code fences or preamble.
+- Return ONLY the JSON object.`;
+}

src/main/ai/schema.ts

@@ -0,0 +1,41 @@
+import { z } from 'zod';
+
+const KOREAN_REGEX = /[가-힣]/;
+const KEBAB_REGEX = /^[a-z0-9]+(-[a-z0-9]+)*$/;
+
+const RawResponseSchema = z.object({
+  title: z.string().trim().min(1).max(200),
+  summary: z.string().min(1),
+  tags: z.array(z.string()).default([])
+});
+
+export interface AiResponse {
+  title: string;
+  summary: string;
+  tags: string[];
+}
+
+function normalizeSummary(raw: string): string {
+  const lines = raw.split(/\r?\n/).map((l) => l.trim()).filter((l) => l.length > 0);
+  if (lines.length === 0) throw new Error('summary is empty');
+  if (lines.length === 3) return lines.join('\n');
+  if (lines.length < 3) {
+    while (lines.length < 3) lines.push('');
+    return lines.join('\n');
+  }
+  const head = lines.slice(0, 2);
+  const tail = lines.slice(2).join(' ');
+  return [...head, tail].join('\n');
+}
+
+export function parseAiResponse(raw: unknown): AiResponse {
+  const parsed = RawResponseSchema.parse(raw);
+  if (!KOREAN_REGEX.test(parsed.title)) {
+    throw new Error('title must contain Korean characters');
+  }
+  return {
+    title: parsed.title.slice(0, 60),
+    summary: normalizeSummary(parsed.summary),
+    tags: parsed.tags.filter((t) => KEBAB_REGEX.test(t)).slice(0, 3)
+  };
+}

tests/unit/ai-schema.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect } from 'vitest';
+import { parseAiResponse } from '@main/ai/schema.js';
+
+describe('parseAiResponse', () => {
+  it('accepts valid Korean title, 3-line summary, kebab tags', () => {
+    const r = parseAiResponse({
+      title: '회의 요약',
+      summary: '첫 줄\n둘째 줄\n셋째 줄',
+      tags: ['api-timeout', 'meeting']
+    });
+    expect(r.title).toBe('회의 요약');
+    expect(r.summary.split('\n')).toHaveLength(3);
+    expect(r.tags).toEqual(['api-timeout', 'meeting']);
+  });
+
+  it('rejects title without Korean', () => {
+    expect(() =>
+      parseAiResponse({ title: 'English only', summary: 'a\nb\nc', tags: [] })
+    ).toThrow(/korean/i);
+  });
+
+  it('pads short summary to 3 lines', () => {
+    const r = parseAiResponse({ title: '제목', summary: '한 줄', tags: [] });
+    expect(r.summary.split('\n')).toHaveLength(3);
+  });
+
+  it('compresses long summary to 3 lines', () => {
+    const r = parseAiResponse({
+      title: '제목', summary: 'a\nb\nc\nd\ne', tags: []
+    });
+    const lines = r.summary.split('\n');
+    expect(lines).toHaveLength(3);
+    expect(lines[2]).toBe('c d e');
+  });
+
+  it('filters invalid tags', () => {
+    const r = parseAiResponse({
+      title: '제목', summary: 'a\nb\nc',
+      tags: ['good-tag', 'BadCase', 'has space', 'ok2', '']
+    });
+    expect(r.tags).toEqual(['good-tag', 'ok2']);
+  });
+
+  it('caps tags to 3', () => {
+    const r = parseAiResponse({
+      title: '제목', summary: 'a\nb\nc',
+      tags: ['a', 'b', 'c', 'd', 'e']
+    });
+    expect(r.tags).toHaveLength(3);
+  });
+
+  it('rejects non-object input', () => {
+    expect(() => parseAiResponse('nope')).toThrow();
+  });
+});