feat(decisioning): property_list resolver + intersection helper for get_products (#500)

* feat(decisioning): property_list resolver + intersection helper for get_products

Closes #494

Adds capability-gated framework support for buyer-side property_list
filtering in get_products, mirroring the webhook_emit post-adapter
pattern. When Features(property_list_filtering=True) is declared and a
PropertyListFetcher is wired, the framework fetches the buyer's
authorized property IDs and filters the platform's product list
post-adapter, setting response.property_list_applied=True.

https://claude.ai/code/session_01GqPV3vkvFdC6DesCzwKFNQ

* fixup(decisioning/property_list): address pre-PR review blockers

- Remove {exc} interpolation from wire error message to prevent
  auth_token / credential leakage through upstream exception reprs
- Extract property_list_capability_enabled() helper to eliminate
  duplicate getattr chains in handler.py and serve.py
- Export validate_property_list_config and property_list_capability_enabled
  from adcp.decisioning public __all__ so self-managed adopters can
  call the boot guard themselves
- Add two tests for by_id with empty property_ids (strict + permissive)
  confirming the vacuous-subset guard works

https://claude.ai/code/session_01GqPV3vkvFdC6DesCzwKFNQ

---------

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

Author: bokelley

src/adcp/decisioning/__init__.py

@@ -114,6 +114,13 @@ def create_media_buy(
     DecisioningPlatform,
 )
 from adcp.decisioning.platform_router import PlatformRouter
+from adcp.decisioning.property_list import (
+    PropertyListFetcher,
+    filter_products_by_property_list,
+    property_list_capability_enabled,
+    resolve_property_list,
+    validate_property_list_config,
+)
 from adcp.decisioning.registry import (
     ApiKeyCredential,
     BillingMode,
@@ -298,9 +305,14 @@ def __init__(self, *args: object, **kwargs: object) -> None:
     "PostgresTaskRegistry",
     "Proposal",
     "PropertyList",
+    "PropertyListFetcher",
     "PropertyListReference",
     "ProductConfigStore",
+    "property_list_capability_enabled",
     "PropertyListsPlatform",
+    "filter_products_by_property_list",
+    "resolve_property_list",
+    "validate_property_list_config",
     "RateLimitedBuyerAgentRegistry",
     "RateLimitedError",
     "RequestContext",

src/adcp/decisioning/handler.py

@@ -45,6 +45,10 @@
 )
 from adcp.decisioning.implementation_config import ProductConfigStore
 from adcp.decisioning.pagination import _query_hash, apply_framework_pagination
+from adcp.decisioning.property_list import (
+    maybe_apply_property_list_filter,
+    property_list_capability_enabled,
+)
 from adcp.decisioning.webhook_emit import maybe_emit_sync_completion
 from adcp.server.base import ADCPHandler, ToolContext
 
@@ -151,6 +155,7 @@
     from concurrent.futures import ThreadPoolExecutor
 
     from adcp.decisioning.platform import DecisioningPlatform
+    from adcp.decisioning.property_list import PropertyListFetcher
     from adcp.decisioning.registry import BuyerAgent, BuyerAgentRegistry
     from adcp.decisioning.resolve import ResourceResolver
     from adcp.decisioning.state import StateReader
@@ -696,6 +701,7 @@ def __init__(
         auto_emit_completion_webhooks: bool = True,
         buyer_agent_registry: BuyerAgentRegistry | None = None,
         config_store: ProductConfigStore | None = None,
+        property_list_fetcher: PropertyListFetcher | None = None,
     ) -> None:
         super().__init__()
         self._platform = platform
@@ -708,6 +714,7 @@ def __init__(
         self._auto_emit_completion_webhooks = auto_emit_completion_webhooks
         self._buyer_agent_registry = buyer_agent_registry
         self._config_store = config_store
+        self._property_list_fetcher = property_list_fetcher
 
         # Cache whether the platform's create_media_buy accepts 'configs'
         # so we only pay the inspect.signature cost at construction time.
@@ -1076,6 +1083,16 @@ async def get_products(  # type: ignore[override]
                 registry=self._registry,
             ),
         )
+        # Post-adapter: capability-gated property-list filter.
+        response = cast(
+            "GetProductsResponse",
+            await maybe_apply_property_list_filter(
+                params=params,
+                response=response,
+                fetcher=self._property_list_fetcher,
+                capability_enabled=property_list_capability_enabled(self._platform),
+            ),
+        )
         if self._platform.capabilities.auto_paginate and params.pagination is not None:
             response = cast(
                 "GetProductsResponse",