Task 003: add postgres schema and seed data

apps/backend/alembic/env.py

@@ -0,0 +1,68 @@
+from __future__ import annotations
+
+import os
+import sys
+from logging.config import fileConfig
+from pathlib import Path
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+
+BACKEND_ROOT = Path(__file__).resolve().parents[1]
+for import_root in (BACKEND_ROOT, BACKEND_ROOT.parents[1]):
+    if (import_root / "src").exists():
+        sys.path.insert(0, str(import_root))
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = None
+
+
+def _database_url() -> str:
+    configured = os.environ.get("DATABASE_URL") or os.environ.get("POSTGRES_DSN")
+    if not configured:
+        return config.get_main_option("sqlalchemy.url")
+
+    if configured.startswith("postgresql://"):
+        return "postgresql+psycopg://" + configured.removeprefix("postgresql://")
+    if configured.startswith("postgres://"):
+        return "postgresql+psycopg://" + configured.removeprefix("postgres://")
+    return configured
+
+
+def run_migrations_offline() -> None:
+    context.configure(
+        url=_database_url(),
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    configuration = config.get_section(config.config_ini_section, {})
+    configuration["sqlalchemy.url"] = _database_url()
+    connectable = engine_from_config(
+        configuration,
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

apps/backend/alembic/script.py.mako

@@ -0,0 +1,26 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+"""
+
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

apps/backend/alembic/versions/202605210003_initial_postgres_schema.py

@@ -0,0 +1,45 @@
+"""initial postgres schema
+
+Revision ID: 202605210003
+Revises:
+Create Date: 2026-05-21 00:03:00.000000
+"""
+
+from __future__ import annotations
+
+from alembic import op
+
+from src.infrastructure.schema import POSTGRES_SCHEMA_STATEMENTS
+
+
+revision = "202605210003"
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    for statement in POSTGRES_SCHEMA_STATEMENTS:
+        op.execute(statement)
+
+
+def downgrade() -> None:
+    for table_name in (
+        "prompt_versions",
+        "publish_commits",
+        "research_run_manifests",
+        "agent_jobs",
+        "workflow_events",
+        "assets",
+        "article_drafts",
+        "claims",
+        "evidence_items",
+        "plan_sections",
+        "article_plans",
+        "boundary_questions",
+        "articles",
+        "script_config_versions",
+        "target_sites",
+        "users",
+    ):
+        op.execute(f"DROP TABLE IF EXISTS {table_name} CASCADE")