Merge branch 'feat/tool-definition-manifest' into dev

Conflicts resolved:
- models/__init__.py: kept both TerminalSessionModel (from dev) and
  ToolDefinitionManifest (from feature branch)
- alembic migration: kept full migration (already applied to DB)
- openspec/config.yaml: kept full config with SDD settings

apps/api/src/models/__init__.py

@@ -4,6 +4,7 @@ from src.models.config_profile import ConfigProfile, ConfigProfileInclude
 from src.models.git_repository import GitRepository
 from src.models.project import Project
 from src.models.ssh_key import SSHKey
+from src.models.terminal_session import TerminalSessionModel
 from src.models.tool_definition_manifest import ToolDefinitionManifest
 from src.models.tool_instance import ToolInstance
 from src.models.tool_type import ToolType
@@ -18,6 +19,7 @@ __all__ = [
     "GitRepository",
     "Project",
     "SSHKey",
+    "TerminalSessionModel",
     "ToolDefinitionManifest",
     "ToolInstance",
     "ToolType",

apps/api/src/models/terminal_session.py

@@ -0,0 +1,37 @@
+"""Terminal session database model."""
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String
+from sqlalchemy import Uuid as UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from src.models.base import Base, TimestampMixin, UUIDPrimaryKeyMixin
+
+
+class TerminalSessionModel(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    """Database model for terminal session metadata."""
+
+    __tablename__ = "terminal_sessions"
+
+    instance_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(),
+        ForeignKey("tool_instances.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    name: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    status: Mapped[str] = mapped_column(
+        String(50),
+        nullable=False,
+        default="active",
+    )
+    last_activity_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    closed_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )