feat(db): ORM models + Alembic migrations 0001–0003 — T09/T10/T11

SQLAlchemy ORM (src/activity_core/orm.py):
  - ActivityDefinition, ActivityRun, TaskInstance mapped to Base.metadata
  - Wired into migrations/env.py for autogenerate support

Migrations (chained 0001 → 0002 → 0003):
  - 0001: activity_definitions (id, name, enabled, trigger_type,
          trigger_config JSONB, context_sources JSONB, task_templates JSONB,
          dedupe_key_strategy, version, created_at, updated_at)
  - 0002: activity_runs (run_id, activity_id FK→activity_definitions,
          scheduled_for, fired_at, context_snapshot JSONB, tasks_spawned,
          version_used) + index on activity_id
  - 0003: task_instances (id, run_id FK→activity_runs CASCADE,
          type, params JSONB, status, created_at) + index on run_id

Apply with: ACTCORE_DB_URL=... alembic upgrade head

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

migrations/env.py

@@ -8,7 +8,8 @@ from sqlalchemy.ext.asyncio import async_engine_from_config
 
 from alembic import context
 
-from activity_core.db import Base  # noqa: F401 — imports all ORM models via submodules
+from activity_core.db import Base  # noqa: F401
+import activity_core.orm  # noqa: F401 — registers all ORM tables into Base.metadata
 
 # Alembic Config object — access to values in alembic.ini
 config = context.config

migrations/versions/0001_create_activity_definitions.py

@@ -0,0 +1,51 @@
+"""create_activity_definitions
+
+Revision ID: 0001
+Revises:
+Create Date: 2026-03-26
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision: str = "0001"
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "activity_definitions",
+        sa.Column("id", sa.UUID(), nullable=False),
+        sa.Column("name", sa.Text(), nullable=False),
+        sa.Column("enabled", sa.Boolean(), nullable=False, server_default="true"),
+        sa.Column("trigger_type", sa.Text(), nullable=False),
+        sa.Column("trigger_config", JSONB(), nullable=False),
+        sa.Column("context_sources", JSONB(), nullable=False, server_default="[]"),
+        sa.Column("task_templates", JSONB(), nullable=False, server_default="[]"),
+        sa.Column(
+            "dedupe_key_strategy", sa.Text(), nullable=False, server_default="skip"
+        ),
+        sa.Column("version", sa.Integer(), nullable=False, server_default="1"),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("activity_definitions")

migrations/versions/0002_create_activity_runs.py

@@ -0,0 +1,47 @@
+"""create_activity_runs
+
+Revision ID: 0002
+Revises: 0001
+Create Date: 2026-03-26
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision: str = "0002"
+down_revision: Union[str, Sequence[str], None] = "0001"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "activity_runs",
+        sa.Column("run_id", sa.UUID(), nullable=False),
+        sa.Column("activity_id", sa.UUID(), nullable=False),
+        sa.Column("scheduled_for", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "fired_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.Column("context_snapshot", JSONB(), nullable=False, server_default="{}"),
+        sa.Column("tasks_spawned", sa.Integer(), nullable=False, server_default="0"),
+        sa.Column("version_used", sa.Integer(), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["activity_id"],
+            ["activity_definitions.id"],
+            ondelete="RESTRICT",
+        ),
+        sa.PrimaryKeyConstraint("run_id"),
+    )
+    op.create_index("ix_activity_runs_activity_id", "activity_runs", ["activity_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_activity_runs_activity_id", table_name="activity_runs")
+    op.drop_table("activity_runs")

migrations/versions/0003_create_task_instances.py

@@ -0,0 +1,46 @@
+"""create_task_instances
+
+Revision ID: 0003
+Revises: 0002
+Create Date: 2026-03-26
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision: str = "0003"
+down_revision: Union[str, Sequence[str], None] = "0002"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "task_instances",
+        sa.Column("id", sa.UUID(), nullable=False),
+        sa.Column("run_id", sa.UUID(), nullable=False),
+        sa.Column("type", sa.Text(), nullable=False),
+        sa.Column("params", JSONB(), nullable=False, server_default="{}"),
+        sa.Column("status", sa.Text(), nullable=False, server_default="pending"),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.ForeignKeyConstraint(
+            ["run_id"],
+            ["activity_runs.run_id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index("ix_task_instances_run_id", "task_instances", ["run_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_task_instances_run_id", table_name="task_instances")
+    op.drop_table("task_instances")