diff --git a/backend/app/schemas/task.py b/backend/app/schemas/task.py
new file mode 100644
index 0000000..7051578
--- /dev/null
+++ b/backend/app/schemas/task.py
@@ -0,0 +1,77 @@
+"""Task schemas."""
+from pydantic import BaseModel, Field
+from typing import Optional, Any
+from datetime import datetime
+
+
+class TaskCreate(BaseModel):
+    title: str = Field(..., min_length=1, max_length=500)
+    description: str = ""
+    priority: str = "medium"
+    task_type: str = "single_call"
+    input_data: str = ""  # JSON string: {prompt, context, parameters}
+    requires_review: bool = True
+    assignee_id: Optional[int] = None
+    worker_id: Optional[int] = None
+    due_date: Optional[datetime] = None
+    depends_on: str = "[]"
+
+
+class TaskUpdate(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    status: Optional[str] = None
+    priority: Optional[str] = None
+    assignee_id: Optional[int] = None
+    worker_id: Optional[int] = None
+    input_data: Optional[str] = None
+    requires_review: Optional[bool] = None
+    due_date: Optional[datetime] = None
+    depends_on: Optional[str] = None
+
+
+class TaskAssign(BaseModel):
+    assignee_id: Optional[int] = None
+    worker_id: Optional[int] = None
+
+
+class TaskExecute(BaseModel):
+    """Trigger task execution."""
+    override_input: Optional[str] = None  # override task input_data
+    max_retries: int = 3
+
+
+class TaskResponse(BaseModel):
+    id: int
+    project_id: int
+    title: str
+    description: str
+    status: str
+    priority: str
+    assignee_id: Optional[int] = None
+    worker_id: Optional[int] = None
+    task_type: str
+    input_data: str
+    output_data: Optional[str] = None
+    requires_review: bool
+    review_status: Optional[str] = None
+    due_date: Optional[datetime] = None
+    started_at: Optional[datetime] = None
+    completed_at: Optional[datetime] = None
+    tenant_id: int
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = {"from_attributes": True}
+
+
+class TaskExecutionResult(BaseModel):
+    """Result of executing a task via AI Worker."""
+    task_id: int
+    status: str  # success, error, needs_review
+    output: str = ""
+    token_usage: int = 0
+    cost_cents: int = 0
+    duration_ms: int = 0
+    error: Optional[str] = None
+    artifact_id: Optional[int] = None