feat(mystery): add Zod schemas for markdown frontmatter

Defines runtime validation schemas (roomFrontmatterSchema,
itemFrontmatterSchema, endingFrontmatterSchema, encounterFrontmatterSchema)
and their inferred TypeScript types. All 8 TDD tests pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/world/schema.test.ts

@@ -0,0 +1,81 @@
+import { describe, it, expect } from 'vitest'
+import { roomFrontmatterSchema, itemFrontmatterSchema, endingFrontmatterSchema, encounterFrontmatterSchema } from './schema'
+
+describe('roomFrontmatterSchema', () => {
+  it('accepts a fully populated room', () => {
+    const data = {
+      id: 'foyer',
+      title: '[ Foyer ]',
+      exitN: 'hallway',
+      exitS: null,
+      exitE: null,
+      exitW: null,
+      exitU: null,
+      exitD: null,
+      items: ['letter'],
+      encounter: null,
+      safe: true,
+    }
+    expect(() => roomFrontmatterSchema.parse(data)).not.toThrow()
+  })
+
+  it('accepts a locked exit with sibling fields', () => {
+    const data = {
+      id: 'hall',
+      title: '[ Hall ]',
+      exitN: null, exitS: null, exitE: null, exitW: null, exitU: null,
+      exitD: 'vault',
+      exitDRequires: 'rusted-key',
+      exitDLockedText: 'The door is locked.',
+      items: [],
+    }
+    expect(() => roomFrontmatterSchema.parse(data)).not.toThrow()
+  })
+
+  it('rejects a room missing a required exit field', () => {
+    const data = { id: 'r', title: '[ R ]', exitN: null, items: [] }
+    expect(() => roomFrontmatterSchema.parse(data)).toThrow()
+  })
+})
+
+describe('itemFrontmatterSchema', () => {
+  it('accepts an item with state', () => {
+    const data = {
+      id: 'lamp',
+      names: ['lamp', 'oil lamp'],
+      short: 'an oil lamp',
+      takeable: true,
+      initialState: { lit: false },
+    }
+    expect(() => itemFrontmatterSchema.parse(data)).not.toThrow()
+  })
+
+  it('accepts an item without state (defaults to {})', () => {
+    const parsed = itemFrontmatterSchema.parse({
+      id: 'letter',
+      names: ['letter'],
+      short: 'a letter',
+      takeable: true,
+    })
+    expect(parsed.initialState).toEqual({})
+  })
+})
+
+describe('endingFrontmatterSchema', () => {
+  it('accepts true ending shape', () => {
+    const data = { id: 'true', whenFlags: { ratGone: true } }
+    expect(() => endingFrontmatterSchema.parse(data)).not.toThrow()
+  })
+
+  it('rejects unknown ending id', () => {
+    const data = { id: 'mercy', whenFlags: {} }
+    expect(() => endingFrontmatterSchema.parse(data)).toThrow()
+  })
+})
+
+describe('encounterFrontmatterSchema', () => {
+  it('accepts an encounter narration doc', () => {
+    const data = { id: 'rat', startsIn: 'cellar-stair', initialPhase: 'lurking' }
+    expect(() => encounterFrontmatterSchema.parse(data)).not.toThrow()
+  })
+})

src/world/schema.ts

@@ -0,0 +1,57 @@
+import { z } from 'zod'
+
+const stateValueSchema = z.union([z.string(), z.boolean(), z.number()])
+const stateRecordSchema = z.record(z.string(), stateValueSchema)
+
+export const roomFrontmatterSchema = z.object({
+  id: z.string().min(1),
+  title: z.string().min(1),
+  exitN: z.string().nullable(),
+  exitS: z.string().nullable(),
+  exitE: z.string().nullable(),
+  exitW: z.string().nullable(),
+  exitU: z.string().nullable(),
+  exitD: z.string().nullable(),
+  exitNRequires: z.string().optional(),
+  exitNLockedText: z.string().optional(),
+  exitSRequires: z.string().optional(),
+  exitSLockedText: z.string().optional(),
+  exitERequires: z.string().optional(),
+  exitELockedText: z.string().optional(),
+  exitWRequires: z.string().optional(),
+  exitWLockedText: z.string().optional(),
+  exitURequires: z.string().optional(),
+  exitULockedText: z.string().optional(),
+  exitDRequires: z.string().optional(),
+  exitDLockedText: z.string().optional(),
+  items: z.array(z.string()).default([]),
+  encounter: z.string().nullable().optional(),
+  safe: z.boolean().optional(),
+})
+
+export type RoomFrontmatter = z.infer<typeof roomFrontmatterSchema>
+
+export const itemFrontmatterSchema = z.object({
+  id: z.string().min(1),
+  names: z.array(z.string().min(1)).min(1),
+  short: z.string().min(1),
+  takeable: z.boolean(),
+  initialState: stateRecordSchema.default({}),
+})
+
+export type ItemFrontmatter = z.infer<typeof itemFrontmatterSchema>
+
+export const endingFrontmatterSchema = z.object({
+  id: z.enum(['true', 'wrong', 'bad']),
+  whenFlags: stateRecordSchema.default({}),
+})
+
+export type EndingFrontmatter = z.infer<typeof endingFrontmatterSchema>
+
+export const encounterFrontmatterSchema = z.object({
+  id: z.string().min(1),
+  startsIn: z.string().min(1),
+  initialPhase: z.string().min(1),
+})
+
+export type EncounterFrontmatter = z.infer<typeof encounterFrontmatterSchema>