diff --git a/src/core/schema.ts b/src/core/schema.ts
new file mode 100644
index 0000000..451bb22
--- /dev/null
+++ b/src/core/schema.ts
@@ -0,0 +1,92 @@
+import { z } from 'zod';
+
+export const TaskStatus = z.enum(['open', 'in_progress', 'review', 'done', 'cancelled']);
+export const DecisionStatus = z.enum(['proposed', 'accepted', 'rejected', 'superseded']);
+export const MemoryCategory = z.enum(['architecture', 'product', 'technical', 'implementation', 'lesson']);
+export const Priority = z.enum(['low', 'medium', 'high', 'critical']);
+export const Role = z.enum(['architect', 'implementer', 'reviewer', 'tester']);
+export const DelegationMode = z.enum(['manual', 'suggest', 'auto']);
+
+export const TaskSchema = z.object({
+  id: z.string().regex(/^TSK-\d+$/),
+  title: z.string().min(1),
+  description: z.string().default(''),
+  status: TaskStatus,
+  priority: Priority.default('medium'),
+  role: Role.optional(),
+  assignedTo: z.string().optional(),
+  createdAt: z.string().datetime(),
+  updatedAt: z.string().datetime(),
+  dueDate: z.string().datetime().optional(),
+  tags: z.array(z.string()).default([]),
+  acceptanceCriteria: z.array(z.string()).default([]),
+  sourceHandoff: z.string().optional(),
+});
+
+export const HandoffSchema = z.object({
+  id: z.string().regex(/^HOF-\d+$/),
+  fromRole: z.string().min(1),
+  toRole: z.string().min(1),
+  fromAgent: z.string().optional(),
+  toAgent: z.string().optional(),
+  taskId: z.string().optional(),
+  summary: z.string().min(1),
+  context: z.string().default(''),
+  decisions: z.array(z.string()).default([]),
+  openQuestions: z.array(z.string()).default([]),
+  nextSteps: z.array(z.string()).default([]),
+  createdAt: z.string().datetime(),
+});
+
+export const DecisionSchema = z.object({
+  id: z.string().regex(/^DEC-\d+$/),
+  title: z.string().min(1),
+  status: DecisionStatus.default('accepted'),
+  context: z.string().default(''),
+  decision: z.string().min(1),
+  consequences: z.array(z.string()).default([]),
+  alternatives: z.array(z.string()).default([]),
+  relatedDecisions: z.array(z.string()).default([]),
+  createdAt: z.string().datetime(),
+  updatedAt: z.string().datetime(),
+});
+
+export const MemorySchema = z.object({
+  id: z.string().min(1),
+  title: z.string().min(1),
+  category: MemoryCategory.default('technical'),
+  content: z.string().min(1),
+  tags: z.array(z.string()).default([]),
+  relatedTasks: z.array(z.string()).default([]),
+  relatedDecisions: z.array(z.string()).default([]),
+  createdAt: z.string().datetime(),
+  updatedAt: z.string().datetime(),
+});
+
+export const StatusSchema = z.object({
+  generatedAt: z.string().datetime(),
+  activeTasks: z.array(z.string()).default([]),
+  blockedTasks: z.array(z.string()).default([]),
+  recentDecisions: z.array(z.string()).default([]),
+  recentHandoffs: z.array(z.string()).default([]),
+  summary: z.string().default(''),
+});
+
+export const RoleConfigSchema = z.object({
+  preferredAgent: z.string().min(1),
+  description: z.string().optional(),
+});
+
+export const ConfigSchema = z.object({
+  version: z.literal('1'),
+  projectName: z.string().min(1),
+  delegationMode: DelegationMode.default('suggest'),
+  roles: z.record(z.string(), RoleConfigSchema),
+});
+
+export type Task = z.infer<typeof TaskSchema>;
+export type Handoff = z.infer<typeof HandoffSchema>;
+export type Decision = z.infer<typeof DecisionSchema>;
+export type Memory = z.infer<typeof MemorySchema>;
+export type Status = z.infer<typeof StatusSchema>;
+export type Config = z.infer<typeof ConfigSchema>;
diff --git a/tests/schema.test.ts b/tests/schema.test.ts
new file mode 100644
index 0000000..2583f59
--- /dev/null
+++ b/tests/schema.test.ts
@@ -0,0 +1,28 @@
+import { describe, it, expect } from 'vitest';
+import { TaskSchema, HandoffSchema, DecisionSchema, MemorySchema, StatusSchema, ConfigSchema } from '../src/core/schema.js';
+
+describe('schemas', () => {
+  it('validates a minimal task', () => {
+    const result = TaskSchema.safeParse({
+      id: 'TSK-0001',
+      title: 'Implement DNS cache',
+      description: 'Add local cache',
+      status: 'open',
+      createdAt: '2026-06-24T10:00:00Z',
+      updatedAt: '2026-06-24T10:00:00Z',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects an invalid task id', () => {
+    const result = TaskSchema.safeParse({
+      id: 'task-1',
+      title: 'Implement DNS cache',
+      description: '',
+      status: 'open',
+      createdAt: '2026-06-24T10:00:00Z',
+      updatedAt: '2026-06-24T10:00:00Z',
+    });
+    expect(result.success).toBe(false);
+  });
+});