pg_policy

pg_policy adds an Agent Policy Language (APL) to PostgreSQL for AI-agent guardrails, guidance, and session-aware controls. It complements—not replaces—row-level security.

Install

make install
psql -c "CREATE EXTENSION pg_policy;"

Quick start

SELECT pg_policy.upsert_policy('block_ddl', $apl$
forbid
  principal agent "research_bot"
  action tool "execute_sql"
  when { context.statement_type in ["DROP", "TRUNCATE", "ALTER", "CREATE"] }
  reason "Research agents may not run DDL"
$apl$);

SELECT pg_policy.set_setting('enforcement_mode', 'enforce');

SELECT pg_policy.evaluate(
  'agent', 'research_bot', 'tool', 'execute_sql',
  '*', '*', '{"statement_type":"DROP"}'::jsonb
);

Concepts

Concept Role
Guardrail (forbid/permit) Hard authorization
Guidance (guide) Soft obligations and advice
Session events Temporal quotas and prerequisites
Decision log Audit trail for every evaluation
Enforcement mode log_only → guide → enforce

See also