feat(ai): zod due_date field + prompt {{TODAY_KST}} injection

AiResponse extends with dueDate: string|null. zod regex
^\d{4}-\d{2}-\d{2}$, follow-up roundtrip check coerces invalid
dates (2026-13-99 etc.) to null. PROMPT_VERSION → 2: prompt now
takes todayKst arg, asks model to extract due_date as ISO or null.

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

src/main/ai/prompt.ts

@@ -1,8 +1,10 @@
-export const PROMPT_VERSION = 1;
+export const PROMPT_VERSION = 2;
 
-export function buildPrompt(rawText: string): string {
+export function buildPrompt(rawText: string, todayKst: string): string {
   return `You organize raw personal notes into structured metadata.
 
+Today's date in Korea Standard Time (KST): ${todayKst}
+
 Input note (raw text, may be fragmented, any language):
 ---
 ${rawText}
@@ -12,10 +14,12 @@ Return a JSON object with EXACTLY these keys:
 - "title": concise title in KOREAN (max 60 chars)
 - "summary": 3-line summary in KOREAN. Each line max 120 chars. Lines separated by "\\n".
 - "tags": array of 0 to 3 tags in lowercase kebab-case (English letters and digits only, e.g., "api-timeout", "weekly-retro"). Empty array if no clear tags.
+- "due_date": ISO YYYY-MM-DD date if you can clearly extract a deadline relative to today (${todayKst} KST), else null. Examples: "월말" → last day of current month; "주말" → upcoming Saturday; "퇴근 전" → today. Be conservative — only return a date if confident.
 
 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).
+- due_date MUST be ISO YYYY-MM-DD format or null. Never include time-of-day.
 - 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

@@ -2,17 +2,20 @@ import { z } from 'zod';
 
 const KOREAN_REGEX = /[가-힣]/;
 const KEBAB_REGEX = /^[a-z0-9]+(-[a-z0-9]+)*$/;
+const ISO_DATE_REGEX = /^\d{4}-\d{2}-\d{2}$/;
 
 const RawResponseSchema = z.object({
   title: z.string().trim().min(1).max(200),
   summary: z.string().min(1),
-  tags: z.array(z.string()).default([])
+  tags: z.array(z.string()).default([]),
+  due_date: z.string().regex(ISO_DATE_REGEX).nullable().optional()
 });
 
 export interface AiResponse {
   title: string;
   summary: string;
   tags: string[];
+  dueDate: string | null;
 }
 
 function normalizeSummary(raw: string): string {
@@ -28,6 +31,14 @@ function normalizeSummary(raw: string): string {
   return [...head, tail].join('\n');
 }
 
+function validateDueDate(d: string | null | undefined): string | null {
+  if (d === null || d === undefined) return null;
+  // Re-verify the date is actually valid (regex passes 2026-13-99 which is invalid)
+  const dt = new Date(d + 'T00:00:00Z');
+  if (Number.isNaN(dt.getTime()) || dt.toISOString().slice(0, 10) !== d) return null;
+  return d;
+}
+
 export function parseAiResponse(raw: unknown): AiResponse {
   const parsed = RawResponseSchema.parse(raw);
   if (!KOREAN_REGEX.test(parsed.title)) {
@@ -36,6 +47,7 @@ export function parseAiResponse(raw: unknown): AiResponse {
   return {
     title: parsed.title.slice(0, 60),
     summary: normalizeSummary(parsed.summary),
-    tags: parsed.tags.filter((t) => KEBAB_REGEX.test(t)).slice(0, 3)
+    tags: parsed.tags.filter((t) => KEBAB_REGEX.test(t)).slice(0, 3),
+    dueDate: validateDueDate(parsed.due_date)
   };
 }

tests/unit/ai-schema.test.ts

@@ -52,4 +52,49 @@ describe('parseAiResponse', () => {
   it('rejects non-object input', () => {
     expect(() => parseAiResponse('nope')).toThrow();
   });
+
+  it('parses note with valid due_date', () => {
+    const r = parseAiResponse({
+      title: '내일 회의',
+      summary: 'a\nb\nc',
+      tags: [],
+      due_date: '2026-04-27'
+    });
+    expect(r.dueDate).toBe('2026-04-27');
+  });
+
+  it('null due_date passes through', () => {
+    const r = parseAiResponse({
+      title: '내일 회의',
+      summary: 'a\nb\nc',
+      tags: []
+    });
+    expect(r.dueDate).toBeNull();
+  });
+
+  it('explicit null due_date passes through', () => {
+    const r = parseAiResponse({
+      title: '내일 회의',
+      summary: 'a\nb\nc',
+      tags: [],
+      due_date: null
+    });
+    expect(r.dueDate).toBeNull();
+  });
+
+  it('rejects malformed due_date string', () => {
+    expect(() =>
+      parseAiResponse({ title: '내일', summary: 'a\nb\nc', tags: [], due_date: 'tomorrow' })
+    ).toThrow();
+  });
+
+  it('coerces invalid date that passes regex (e.g. 2026-13-99) to null', () => {
+    const r = parseAiResponse({
+      title: '내일 회의',
+      summary: 'a\nb\nc',
+      tags: [],
+      due_date: '2026-13-99'
+    });
+    expect(r.dueDate).toBeNull();
+  });
 });