feat(backend): Add Syndarix domain models with CRUD operations

- Add Project model with slug, description, autonomy level, and settings
- Add AgentType model for agent templates with model config and failover
- Add AgentInstance model for running agents with status and memory
- Add Issue model with external tracker sync (Gitea/GitHub/GitLab)
- Add Sprint model with velocity tracking and lifecycle management
- Add comprehensive Pydantic schemas with validation
- Add full CRUD operations for all models with filtering/sorting
- Add 280+ tests for models, schemas, and CRUD operations

Implements #23, #24, #25, #26, #27

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/schemas/syndarix/__init__.py

@@ -0,0 +1,113 @@
+# app/schemas/syndarix/__init__.py
+"""
+Syndarix domain schemas.
+
+This package contains Pydantic schemas for validating and serializing
+Syndarix domain entities.
+"""
+
+from .agent_instance import (
+    AgentInstanceCreate,
+    AgentInstanceInDB,
+    AgentInstanceListResponse,
+    AgentInstanceMetrics,
+    AgentInstanceResponse,
+    AgentInstanceTerminate,
+    AgentInstanceUpdate,
+)
+from .agent_type import (
+    AgentTypeCreate,
+    AgentTypeInDB,
+    AgentTypeListResponse,
+    AgentTypeResponse,
+    AgentTypeUpdate,
+)
+from .enums import (
+    AgentStatus,
+    AutonomyLevel,
+    IssuePriority,
+    IssueStatus,
+    ProjectStatus,
+    SprintStatus,
+    SyncStatus,
+)
+from .issue import (
+    IssueAssign,
+    IssueClose,
+    IssueCreate,
+    IssueInDB,
+    IssueListResponse,
+    IssueResponse,
+    IssueStats,
+    IssueSyncUpdate,
+    IssueUpdate,
+)
+from .project import (
+    ProjectCreate,
+    ProjectInDB,
+    ProjectListResponse,
+    ProjectResponse,
+    ProjectUpdate,
+)
+from .sprint import (
+    SprintBurndown,
+    SprintComplete,
+    SprintCreate,
+    SprintInDB,
+    SprintListResponse,
+    SprintResponse,
+    SprintStart,
+    SprintUpdate,
+    SprintVelocity,
+)
+
+__all__ = [
+    # AgentInstance schemas
+    "AgentInstanceCreate",
+    "AgentInstanceInDB",
+    "AgentInstanceListResponse",
+    "AgentInstanceMetrics",
+    "AgentInstanceResponse",
+    "AgentInstanceTerminate",
+    "AgentInstanceUpdate",
+    # Enums
+    "AgentStatus",
+    # AgentType schemas
+    "AgentTypeCreate",
+    "AgentTypeInDB",
+    "AgentTypeListResponse",
+    "AgentTypeResponse",
+    "AgentTypeUpdate",
+    "AutonomyLevel",
+    # Issue schemas
+    "IssueAssign",
+    "IssueClose",
+    "IssueCreate",
+    "IssueInDB",
+    "IssueListResponse",
+    "IssuePriority",
+    "IssueResponse",
+    "IssueStats",
+    "IssueStatus",
+    "IssueSyncUpdate",
+    "IssueUpdate",
+    # Project schemas
+    "ProjectCreate",
+    "ProjectInDB",
+    "ProjectListResponse",
+    "ProjectResponse",
+    "ProjectStatus",
+    "ProjectUpdate",
+    # Sprint schemas
+    "SprintBurndown",
+    "SprintComplete",
+    "SprintCreate",
+    "SprintInDB",
+    "SprintListResponse",
+    "SprintResponse",
+    "SprintStart",
+    "SprintStatus",
+    "SprintUpdate",
+    "SprintVelocity",
+    "SyncStatus",
+]

backend/app/schemas/syndarix/agent_instance.py

@@ -0,0 +1,122 @@
+# app/schemas/syndarix/agent_instance.py
+"""
+Pydantic schemas for AgentInstance entity.
+"""
+
+from datetime import datetime
+from decimal import Decimal
+from typing import Any
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field
+
+from .enums import AgentStatus
+
+
+class AgentInstanceBase(BaseModel):
+    """Base agent instance schema with common fields."""
+
+    agent_type_id: UUID
+    project_id: UUID
+    status: AgentStatus = AgentStatus.IDLE
+    current_task: str | None = None
+    short_term_memory: dict[str, Any] = Field(default_factory=dict)
+    long_term_memory_ref: str | None = Field(None, max_length=500)
+    session_id: str | None = Field(None, max_length=255)
+
+
+class AgentInstanceCreate(BaseModel):
+    """Schema for creating a new agent instance."""
+
+    agent_type_id: UUID
+    project_id: UUID
+    status: AgentStatus = AgentStatus.IDLE
+    current_task: str | None = None
+    short_term_memory: dict[str, Any] = Field(default_factory=dict)
+    long_term_memory_ref: str | None = Field(None, max_length=500)
+    session_id: str | None = Field(None, max_length=255)
+
+
+class AgentInstanceUpdate(BaseModel):
+    """Schema for updating an agent instance."""
+
+    status: AgentStatus | None = None
+    current_task: str | None = None
+    short_term_memory: dict[str, Any] | None = None
+    long_term_memory_ref: str | None = None
+    session_id: str | None = None
+    last_activity_at: datetime | None = None
+    tasks_completed: int | None = Field(None, ge=0)
+    tokens_used: int | None = Field(None, ge=0)
+    cost_incurred: Decimal | None = Field(None, ge=0)
+
+
+class AgentInstanceTerminate(BaseModel):
+    """Schema for terminating an agent instance."""
+
+    reason: str | None = None
+
+
+class AgentInstanceInDB(AgentInstanceBase):
+    """Schema for agent instance in database."""
+
+    id: UUID
+    last_activity_at: datetime | None = None
+    terminated_at: datetime | None = None
+    tasks_completed: int = 0
+    tokens_used: int = 0
+    cost_incurred: Decimal = Decimal("0.0000")
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AgentInstanceResponse(BaseModel):
+    """Schema for agent instance API responses."""
+
+    id: UUID
+    agent_type_id: UUID
+    project_id: UUID
+    status: AgentStatus
+    current_task: str | None = None
+    short_term_memory: dict[str, Any] = Field(default_factory=dict)
+    long_term_memory_ref: str | None = None
+    session_id: str | None = None
+    last_activity_at: datetime | None = None
+    terminated_at: datetime | None = None
+    tasks_completed: int = 0
+    tokens_used: int = 0
+    cost_incurred: Decimal = Decimal("0.0000")
+    created_at: datetime
+    updated_at: datetime
+
+    # Expanded fields from relationships
+    agent_type_name: str | None = None
+    agent_type_slug: str | None = None
+    project_name: str | None = None
+    project_slug: str | None = None
+    assigned_issues_count: int | None = 0
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AgentInstanceListResponse(BaseModel):
+    """Schema for paginated agent instance list responses."""
+
+    agent_instances: list[AgentInstanceResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int
+
+
+class AgentInstanceMetrics(BaseModel):
+    """Schema for agent instance metrics summary."""
+
+    total_instances: int
+    active_instances: int
+    idle_instances: int
+    total_tasks_completed: int
+    total_tokens_used: int
+    total_cost_incurred: Decimal

backend/app/schemas/syndarix/agent_type.py

@@ -0,0 +1,151 @@
+# app/schemas/syndarix/agent_type.py
+"""
+Pydantic schemas for AgentType entity.
+"""
+
+import re
+from datetime import datetime
+from typing import Any
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator
+
+
+class AgentTypeBase(BaseModel):
+    """Base agent type schema with common fields."""
+
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: str | None = Field(None, min_length=1, max_length=255)
+    description: str | None = None
+    expertise: list[str] = Field(default_factory=list)
+    personality_prompt: str = Field(..., min_length=1)
+    primary_model: str = Field(..., min_length=1, max_length=100)
+    fallback_models: list[str] = Field(default_factory=list)
+    model_params: dict[str, Any] = Field(default_factory=dict)
+    mcp_servers: list[str] = Field(default_factory=list)
+    tool_permissions: dict[str, Any] = Field(default_factory=dict)
+    is_active: bool = True
+
+    @field_validator("slug")
+    @classmethod
+    def validate_slug(cls, v: str | None) -> str | None:
+        """Validate slug format: lowercase, alphanumeric, hyphens only."""
+        if v is None:
+            return v
+        if not re.match(r"^[a-z0-9-]+$", v):
+            raise ValueError(
+                "Slug must contain only lowercase letters, numbers, and hyphens"
+            )
+        if v.startswith("-") or v.endswith("-"):
+            raise ValueError("Slug cannot start or end with a hyphen")
+        if "--" in v:
+            raise ValueError("Slug cannot contain consecutive hyphens")
+        return v
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str) -> str:
+        """Validate agent type name."""
+        if not v or v.strip() == "":
+            raise ValueError("Agent type name cannot be empty")
+        return v.strip()
+
+    @field_validator("expertise")
+    @classmethod
+    def validate_expertise(cls, v: list[str]) -> list[str]:
+        """Validate and normalize expertise list."""
+        return [e.strip().lower() for e in v if e.strip()]
+
+    @field_validator("mcp_servers")
+    @classmethod
+    def validate_mcp_servers(cls, v: list[str]) -> list[str]:
+        """Validate MCP server list."""
+        return [s.strip() for s in v if s.strip()]
+
+
+class AgentTypeCreate(AgentTypeBase):
+    """Schema for creating a new agent type."""
+
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: str = Field(..., min_length=1, max_length=255)
+    personality_prompt: str = Field(..., min_length=1)
+    primary_model: str = Field(..., min_length=1, max_length=100)
+
+
+class AgentTypeUpdate(BaseModel):
+    """Schema for updating an agent type."""
+
+    name: str | None = Field(None, min_length=1, max_length=255)
+    slug: str | None = Field(None, min_length=1, max_length=255)
+    description: str | None = None
+    expertise: list[str] | None = None
+    personality_prompt: str | None = None
+    primary_model: str | None = Field(None, min_length=1, max_length=100)
+    fallback_models: list[str] | None = None
+    model_params: dict[str, Any] | None = None
+    mcp_servers: list[str] | None = None
+    tool_permissions: dict[str, Any] | None = None
+    is_active: bool | None = None
+
+    @field_validator("slug")
+    @classmethod
+    def validate_slug(cls, v: str | None) -> str | None:
+        """Validate slug format."""
+        if v is None:
+            return v
+        if not re.match(r"^[a-z0-9-]+$", v):
+            raise ValueError(
+                "Slug must contain only lowercase letters, numbers, and hyphens"
+            )
+        if v.startswith("-") or v.endswith("-"):
+            raise ValueError("Slug cannot start or end with a hyphen")
+        if "--" in v:
+            raise ValueError("Slug cannot contain consecutive hyphens")
+        return v
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str | None) -> str | None:
+        """Validate agent type name."""
+        if v is not None and (not v or v.strip() == ""):
+            raise ValueError("Agent type name cannot be empty")
+        return v.strip() if v else v
+
+    @field_validator("expertise")
+    @classmethod
+    def validate_expertise(cls, v: list[str] | None) -> list[str] | None:
+        """Validate and normalize expertise list."""
+        if v is None:
+            return v
+        return [e.strip().lower() for e in v if e.strip()]
+
+
+class AgentTypeInDB(AgentTypeBase):
+    """Schema for agent type in database."""
+
+    id: UUID
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AgentTypeResponse(AgentTypeBase):
+    """Schema for agent type API responses."""
+
+    id: UUID
+    created_at: datetime
+    updated_at: datetime
+    instance_count: int | None = 0
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AgentTypeListResponse(BaseModel):
+    """Schema for paginated agent type list responses."""
+
+    agent_types: list[AgentTypeResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int

backend/app/schemas/syndarix/enums.py

@@ -0,0 +1,26 @@
+# app/schemas/syndarix/enums.py
+"""
+Re-export enums from models for use in schemas.
+
+This allows schemas to import enums without depending on SQLAlchemy models directly.
+"""
+
+from app.models.syndarix.enums import (
+    AgentStatus,
+    AutonomyLevel,
+    IssuePriority,
+    IssueStatus,
+    ProjectStatus,
+    SprintStatus,
+    SyncStatus,
+)
+
+__all__ = [
+    "AgentStatus",
+    "AutonomyLevel",
+    "IssuePriority",
+    "IssueStatus",
+    "ProjectStatus",
+    "SprintStatus",
+    "SyncStatus",
+]

backend/app/schemas/syndarix/issue.py

@@ -0,0 +1,193 @@
+# app/schemas/syndarix/issue.py
+"""
+Pydantic schemas for Issue entity.
+"""
+
+from datetime import datetime
+from typing import Literal
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator
+
+from .enums import IssuePriority, IssueStatus, SyncStatus
+
+
+class IssueBase(BaseModel):
+    """Base issue schema with common fields."""
+
+    title: str = Field(..., min_length=1, max_length=500)
+    body: str = ""
+    status: IssueStatus = IssueStatus.OPEN
+    priority: IssuePriority = IssuePriority.MEDIUM
+    labels: list[str] = Field(default_factory=list)
+    story_points: int | None = Field(None, ge=0, le=100)
+
+    @field_validator("title")
+    @classmethod
+    def validate_title(cls, v: str) -> str:
+        """Validate issue title."""
+        if not v or v.strip() == "":
+            raise ValueError("Issue title cannot be empty")
+        return v.strip()
+
+    @field_validator("labels")
+    @classmethod
+    def validate_labels(cls, v: list[str]) -> list[str]:
+        """Validate and normalize labels."""
+        return [label.strip().lower() for label in v if label.strip()]
+
+
+class IssueCreate(IssueBase):
+    """Schema for creating a new issue."""
+
+    project_id: UUID
+    assigned_agent_id: UUID | None = None
+    human_assignee: str | None = Field(None, max_length=255)
+    sprint_id: UUID | None = None
+
+    # External tracker fields (optional, for importing from external systems)
+    external_tracker: Literal["gitea", "github", "gitlab"] | None = None
+    external_id: str | None = Field(None, max_length=255)
+    external_url: str | None = Field(None, max_length=1000)
+    external_number: int | None = None
+
+
+class IssueUpdate(BaseModel):
+    """Schema for updating an issue."""
+
+    title: str | None = Field(None, min_length=1, max_length=500)
+    body: str | None = None
+    status: IssueStatus | None = None
+    priority: IssuePriority | None = None
+    labels: list[str] | None = None
+    assigned_agent_id: UUID | None = None
+    human_assignee: str | None = Field(None, max_length=255)
+    sprint_id: UUID | None = None
+    story_points: int | None = Field(None, ge=0, le=100)
+    sync_status: SyncStatus | None = None
+
+    @field_validator("title")
+    @classmethod
+    def validate_title(cls, v: str | None) -> str | None:
+        """Validate issue title."""
+        if v is not None and (not v or v.strip() == ""):
+            raise ValueError("Issue title cannot be empty")
+        return v.strip() if v else v
+
+    @field_validator("labels")
+    @classmethod
+    def validate_labels(cls, v: list[str] | None) -> list[str] | None:
+        """Validate and normalize labels."""
+        if v is None:
+            return v
+        return [label.strip().lower() for label in v if label.strip()]
+
+
+class IssueClose(BaseModel):
+    """Schema for closing an issue."""
+
+    resolution: str | None = None  # Optional resolution note
+
+
+class IssueAssign(BaseModel):
+    """Schema for assigning an issue."""
+
+    assigned_agent_id: UUID | None = None
+    human_assignee: str | None = Field(None, max_length=255)
+
+    @model_validator(mode="after")
+    def validate_assignment(self) -> "IssueAssign":
+        """Ensure only one type of assignee is set."""
+        if self.assigned_agent_id and self.human_assignee:
+            raise ValueError(
+                "Cannot assign to both an agent and a human. Choose one."
+            )
+        return self
+
+
+class IssueSyncUpdate(BaseModel):
+    """Schema for updating sync-related fields."""
+
+    sync_status: SyncStatus
+    last_synced_at: datetime | None = None
+    external_updated_at: datetime | None = None
+
+
+class IssueInDB(IssueBase):
+    """Schema for issue in database."""
+
+    id: UUID
+    project_id: UUID
+    assigned_agent_id: UUID | None = None
+    human_assignee: str | None = None
+    sprint_id: UUID | None = None
+    external_tracker: str | None = None
+    external_id: str | None = None
+    external_url: str | None = None
+    external_number: int | None = None
+    sync_status: SyncStatus = SyncStatus.SYNCED
+    last_synced_at: datetime | None = None
+    external_updated_at: datetime | None = None
+    closed_at: datetime | None = None
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class IssueResponse(BaseModel):
+    """Schema for issue API responses."""
+
+    id: UUID
+    project_id: UUID
+    title: str
+    body: str
+    status: IssueStatus
+    priority: IssuePriority
+    labels: list[str] = Field(default_factory=list)
+    assigned_agent_id: UUID | None = None
+    human_assignee: str | None = None
+    sprint_id: UUID | None = None
+    story_points: int | None = None
+    external_tracker: str | None = None
+    external_id: str | None = None
+    external_url: str | None = None
+    external_number: int | None = None
+    sync_status: SyncStatus = SyncStatus.SYNCED
+    last_synced_at: datetime | None = None
+    external_updated_at: datetime | None = None
+    closed_at: datetime | None = None
+    created_at: datetime
+    updated_at: datetime
+
+    # Expanded fields from relationships
+    project_name: str | None = None
+    project_slug: str | None = None
+    sprint_name: str | None = None
+    assigned_agent_type_name: str | None = None
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class IssueListResponse(BaseModel):
+    """Schema for paginated issue list responses."""
+
+    issues: list[IssueResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int
+
+
+class IssueStats(BaseModel):
+    """Schema for issue statistics."""
+
+    total: int
+    open: int
+    in_progress: int
+    in_review: int
+    blocked: int
+    closed: int
+    by_priority: dict[str, int]
+    total_story_points: int | None = None
+    completed_story_points: int | None = None

backend/app/schemas/syndarix/project.py

@@ -0,0 +1,127 @@
+# app/schemas/syndarix/project.py
+"""
+Pydantic schemas for Project entity.
+"""
+
+import re
+from datetime import datetime
+from typing import Any
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator
+
+from .enums import AutonomyLevel, ProjectStatus
+
+
+class ProjectBase(BaseModel):
+    """Base project schema with common fields."""
+
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: str | None = Field(None, min_length=1, max_length=255)
+    description: str | None = None
+    autonomy_level: AutonomyLevel = AutonomyLevel.MILESTONE
+    status: ProjectStatus = ProjectStatus.ACTIVE
+    settings: dict[str, Any] = Field(default_factory=dict)
+
+    @field_validator("slug")
+    @classmethod
+    def validate_slug(cls, v: str | None) -> str | None:
+        """Validate slug format: lowercase, alphanumeric, hyphens only."""
+        if v is None:
+            return v
+        if not re.match(r"^[a-z0-9-]+$", v):
+            raise ValueError(
+                "Slug must contain only lowercase letters, numbers, and hyphens"
+            )
+        if v.startswith("-") or v.endswith("-"):
+            raise ValueError("Slug cannot start or end with a hyphen")
+        if "--" in v:
+            raise ValueError("Slug cannot contain consecutive hyphens")
+        return v
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str) -> str:
+        """Validate project name."""
+        if not v or v.strip() == "":
+            raise ValueError("Project name cannot be empty")
+        return v.strip()
+
+
+class ProjectCreate(ProjectBase):
+    """Schema for creating a new project."""
+
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: str = Field(..., min_length=1, max_length=255)
+    owner_id: UUID | None = None
+
+
+class ProjectUpdate(BaseModel):
+    """Schema for updating a project."""
+
+    name: str | None = Field(None, min_length=1, max_length=255)
+    slug: str | None = Field(None, min_length=1, max_length=255)
+    description: str | None = None
+    autonomy_level: AutonomyLevel | None = None
+    status: ProjectStatus | None = None
+    settings: dict[str, Any] | None = None
+    owner_id: UUID | None = None
+
+    @field_validator("slug")
+    @classmethod
+    def validate_slug(cls, v: str | None) -> str | None:
+        """Validate slug format."""
+        if v is None:
+            return v
+        if not re.match(r"^[a-z0-9-]+$", v):
+            raise ValueError(
+                "Slug must contain only lowercase letters, numbers, and hyphens"
+            )
+        if v.startswith("-") or v.endswith("-"):
+            raise ValueError("Slug cannot start or end with a hyphen")
+        if "--" in v:
+            raise ValueError("Slug cannot contain consecutive hyphens")
+        return v
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str | None) -> str | None:
+        """Validate project name."""
+        if v is not None and (not v or v.strip() == ""):
+            raise ValueError("Project name cannot be empty")
+        return v.strip() if v else v
+
+
+class ProjectInDB(ProjectBase):
+    """Schema for project in database."""
+
+    id: UUID
+    owner_id: UUID | None = None
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class ProjectResponse(ProjectBase):
+    """Schema for project API responses."""
+
+    id: UUID
+    owner_id: UUID | None = None
+    created_at: datetime
+    updated_at: datetime
+    agent_count: int | None = 0
+    issue_count: int | None = 0
+    active_sprint_name: str | None = None
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class ProjectListResponse(BaseModel):
+    """Schema for paginated project list responses."""
+
+    projects: list[ProjectResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int

backend/app/schemas/syndarix/sprint.py

@@ -0,0 +1,135 @@
+# app/schemas/syndarix/sprint.py
+"""
+Pydantic schemas for Sprint entity.
+"""
+
+from datetime import date, datetime
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator
+
+from .enums import SprintStatus
+
+
+class SprintBase(BaseModel):
+    """Base sprint schema with common fields."""
+
+    name: str = Field(..., min_length=1, max_length=255)
+    number: int = Field(..., ge=1)
+    goal: str | None = None
+    start_date: date
+    end_date: date
+    status: SprintStatus = SprintStatus.PLANNED
+    planned_points: int | None = Field(None, ge=0)
+    completed_points: int | None = Field(None, ge=0)
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str) -> str:
+        """Validate sprint name."""
+        if not v or v.strip() == "":
+            raise ValueError("Sprint name cannot be empty")
+        return v.strip()
+
+    @model_validator(mode="after")
+    def validate_dates(self) -> "SprintBase":
+        """Validate that end_date is after start_date."""
+        if self.end_date < self.start_date:
+            raise ValueError("End date must be after or equal to start date")
+        return self
+
+
+class SprintCreate(SprintBase):
+    """Schema for creating a new sprint."""
+
+    project_id: UUID
+
+
+class SprintUpdate(BaseModel):
+    """Schema for updating a sprint."""
+
+    name: str | None = Field(None, min_length=1, max_length=255)
+    goal: str | None = None
+    start_date: date | None = None
+    end_date: date | None = None
+    status: SprintStatus | None = None
+    planned_points: int | None = Field(None, ge=0)
+    completed_points: int | None = Field(None, ge=0)
+
+    @field_validator("name")
+    @classmethod
+    def validate_name(cls, v: str | None) -> str | None:
+        """Validate sprint name."""
+        if v is not None and (not v or v.strip() == ""):
+            raise ValueError("Sprint name cannot be empty")
+        return v.strip() if v else v
+
+
+class SprintStart(BaseModel):
+    """Schema for starting a sprint."""
+
+    start_date: date | None = None  # Optionally override start date
+
+
+class SprintComplete(BaseModel):
+    """Schema for completing a sprint."""
+
+    completed_points: int | None = Field(None, ge=0)
+    notes: str | None = None
+
+
+class SprintInDB(SprintBase):
+    """Schema for sprint in database."""
+
+    id: UUID
+    project_id: UUID
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class SprintResponse(SprintBase):
+    """Schema for sprint API responses."""
+
+    id: UUID
+    project_id: UUID
+    created_at: datetime
+    updated_at: datetime
+
+    # Expanded fields from relationships
+    project_name: str | None = None
+    project_slug: str | None = None
+    issue_count: int | None = 0
+    open_issues: int | None = 0
+    completed_issues: int | None = 0
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class SprintListResponse(BaseModel):
+    """Schema for paginated sprint list responses."""
+
+    sprints: list[SprintResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int
+
+
+class SprintVelocity(BaseModel):
+    """Schema for sprint velocity metrics."""
+
+    sprint_number: int
+    sprint_name: str
+    planned_points: int | None
+    completed_points: int | None
+    velocity: float | None  # completed/planned ratio
+
+
+class SprintBurndown(BaseModel):
+    """Schema for sprint burndown data point."""
+
+    date: date
+    remaining_points: int
+    ideal_remaining: float