feat(decisioning): PgBuyerAgentRegistry — durable Tier 2 commercial-identity store (#364)

Postgres-backed BuyerAgentRegistry implementation for adopters who
need durable commercial-identity gating without forking the
SQLAlchemy reference example. Mirrors the design of
adcp.signing.pg.PgReplayStore — caller-owned ConnectionPool,
table-name validation, idempotent ``create_schema()``, raw DDL
ships separately for migration tools (Alembic, Flyway, psql).

* ``src/adcp/decisioning/pg/buyer_agent_registry.py`` — sync
  psycopg-pool implementation; the async BuyerAgentRegistry
  Protocol methods bridge via ``asyncio.to_thread`` so the
  framework's dispatch event loop stays responsive.
* ``src/adcp/decisioning/pg/buyer_agent_registry.sql`` — canonical
  schema for migration tools. JSONB columns for billing_capabilities,
  default_terms, allowed_brands, ext. CHECK constraint on status.
  Partial index on api_key_id for the bearer-credential lookup
  path. Partial index on status WHERE status <> 'active' for
  admin tools.
* Admin CRUD: upsert(), set_status(), delete(). Status validated
  against the framework's literal enum.
* SQL injection / Unicode-homoglyph defenses on the table_name
  kwarg matching PgReplayStore's posture.
* 15 conformance tests gated on ADCP_PG_TEST_URL — all 15 pass
  against postgres:16. CI's existing pg job (renamed
  pg-replay-store → pg-conformance) now runs them too.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: bokelley

.github/workflows/ci.yml

@@ -39,8 +39,8 @@ jobs:
         run: |
           pytest tests/ -v --cov=src/adcp --cov-report=term-missing
 
-  pg-replay-store:
-    name: PgReplayStore tests (Postgres 16)
+  pg-conformance:
+    name: Postgres conformance tests (Postgres 16)
     runs-on: ubuntu-latest
     services:
       postgres:
@@ -73,12 +73,13 @@ jobs:
           python -m pip install --upgrade pip
           pip install -e ".[dev,pg]"
 
-      - name: Run PgReplayStore tests (unit + full-wire e2e)
+      - name: Run Postgres conformance tests
         env:
           ADCP_PG_TEST_URL: postgresql://postgres@localhost:5432/adcp_test
         run: |
           pytest tests/conformance/signing/test_pg_replay_store.py \
                  tests/conformance/signing/test_pg_replay_store_e2e.py \
+                 tests/conformance/decisioning/test_pg_buyer_agent_registry.py \
                  -v
 
   conventional-commits:

src/adcp/decisioning/pg/__init__.py

@@ -0,0 +1,32 @@
+"""PostgreSQL-backed implementations for the decisioning module.
+
+Ships durable backends behind the ``[pg]`` optional extra so the
+base ``adcp.decisioning`` import path stays free of SQL dependencies
+for adopters who only need the in-memory primitives.
+
+Available when ``adcp[pg]`` is installed:
+
+* :class:`PgBuyerAgentRegistry` — durable Tier 2 commercial-identity
+  layer for v3 sellers. The framework calls the registry on every
+  request to gate dispatch on the seller's commercial relationship
+  with the buyer agent (allowlist + onboarding state + billing
+  capabilities).
+
+The schema DDL ships alongside the Python code (e.g.
+``adcp/decisioning/pg/buyer_agent_registry.sql``) so adopters can run
+it through whatever migration tool they use (Alembic, Flyway, psql).
+"""
+
+from __future__ import annotations
+
+from adcp.decisioning.pg.buyer_agent_registry import (
+    DEFAULT_TABLE_NAME,
+    PG_AVAILABLE,
+    PgBuyerAgentRegistry,
+)
+
+__all__ = [
+    "DEFAULT_TABLE_NAME",
+    "PG_AVAILABLE",
+    "PgBuyerAgentRegistry",
+]