test(examples): regression test for seller_agent PRODUCTS schema compliance (#324) (#327)

Validates all static products in seller_agent.py against the local AdCP
3.0.1 schema cache via the Python jsonschema validator, anchoring the
Python-side verdict that the CI divergence is in @adcp/client's Ajv
oneOf error reporter rather than in the response shape we emit.

https://claude.ai/code/session_019rDGvdv7HHDKwJeNri9Lff

Co-authored-by: Claude <noreply@anthropic.com>

Author: bokelley

tests/test_seller_agent_products_schema.py

@@ -0,0 +1,67 @@
+"""Regression test: every static product in seller_agent.py is 3.0.1 schema-valid.
+
+Anchors the Python-side verdict on issue #324 (CI vs local divergence with
+@adcp/client@5.21.1's Ajv validator).  The Python jsonschema validator confirms
+all products are compliant; the CI failures are in the npm-side oneOf error
+reporter, not in the response shape we emit.
+"""
+
+from __future__ import annotations
+
+import importlib.util
+from pathlib import Path
+from types import ModuleType
+from typing import Any
+
+import pytest
+
+from adcp.validation.schema_validator import validate_response
+
+
+def _load_seller_agent() -> ModuleType:
+    path = Path(__file__).parent.parent / "examples" / "seller_agent.py"
+    spec = importlib.util.spec_from_file_location("_seller_agent_test_module", path)
+    assert spec is not None and spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+# Snapshot at collection time — seed_product() mutates PRODUCTS in-place, so
+# a bare reference would change parametrize IDs across test runs in the same
+# process if an integration test instantiates DemoStore and calls seed_product.
+_PRODUCTS: list[dict[str, Any]] = list(_load_seller_agent().PRODUCTS)
+
+
+class TestStaticProductsSchemaCompliance:
+    """All static PRODUCTS in seller_agent.py must pass get_products response
+    validation against the local AdCP 3.0.1 schema cache."""
+
+    def test_full_products_list_passes_response_validation(self) -> None:
+        outcome = validate_response("get_products", {"products": _PRODUCTS})
+        assert outcome.variant != "skipped", (
+            "get_products schema not loaded — regression anchor is a no-op; "
+            "check that schemas/cache/ is present"
+        )
+        assert outcome.valid, (
+            f"get_products response with all {len(_PRODUCTS)} products failed "
+            f"Python-side schema validation: {outcome.issues}"
+        )
+
+    @pytest.mark.parametrize(
+        "product",
+        _PRODUCTS,
+        ids=[p["product_id"] for p in _PRODUCTS],
+    )
+    def test_individual_product_passes_response_validation(
+        self, product: dict[str, Any]
+    ) -> None:
+        outcome = validate_response("get_products", {"products": [product]})
+        assert outcome.variant != "skipped", (
+            "get_products schema not loaded — regression anchor is a no-op; "
+            "check that schemas/cache/ is present"
+        )
+        assert outcome.valid, (
+            f"Product {product.get('product_id')!r} failed Python-side schema "
+            f"validation: {outcome.issues}"
+        )