Add event-payload context resolver

src/activity_core/activities.py

@@ -11,6 +11,7 @@ activities that need DB access.
 
 from __future__ import annotations
 
+import json
 import uuid
 from datetime import datetime, timezone
 from typing import Any
@@ -65,6 +66,24 @@ def _bind_resolver_result(bind_key: str, result: Any) -> Any:
     return result
 
 
+def _parse_event_envelope(event_envelope_json: str | None) -> dict[str, Any] | None:
+    """Parse an event envelope JSON string for context resolvers."""
+    if not event_envelope_json:
+        return None
+    try:
+        payload = json.loads(event_envelope_json)
+    except (TypeError, json.JSONDecodeError) as exc:
+        activity.logger.warning("Invalid event envelope JSON - %s", exc)
+        return None
+    if not isinstance(payload, dict):
+        activity.logger.warning(
+            "Invalid event envelope JSON - expected object, got %s",
+            type(payload).__name__,
+        )
+        return None
+    return payload
+
+
 # ── Activities ─────────────────────────────────────────────────────────────────
 
 @activity.defn
@@ -124,6 +143,7 @@ async def resolve_context(
     from activity_core.context_resolvers.base import CONTEXT_RESOLVER_REGISTRY
 
     snapshot: dict = {}
+    event_envelope = _parse_event_envelope(event_envelope_json)
     for source in context_sources:
         source_type = source.get("type", "")
         query = source.get("query", "")
@@ -152,7 +172,7 @@ async def resolve_context(
             continue
 
         try:
-            resolved = resolver_cls().resolve(query, None, params)
+            resolved = resolver_cls().resolve(query, event_envelope, params)
             snapshot[bind_key] = _bind_resolver_result(bind_key, resolved)
         except Exception as exc:
             if required:

src/activity_core/context_resolvers/__init__.py

@@ -1 +1,7 @@
-from activity_core.context_resolvers import kaizen, ops_inventory, repo_scoping, state_hub  # noqa: F401
+from activity_core.context_resolvers import (  # noqa: F401
+    event_payload,
+    kaizen,
+    ops_inventory,
+    repo_scoping,
+    state_hub,
+)

src/activity_core/context_resolvers/event_payload.py

@@ -0,0 +1,51 @@
+"""Event payload context adapter.
+
+Registered as source type ``event-payload``. It exposes the triggering
+EventEnvelope attributes to event-triggered ActivityDefinitions without
+requiring an external context service call.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from activity_core.context_resolvers.base import CONTEXT_RESOLVER_REGISTRY, ContextResolver
+
+
+class EventPayloadContextResolver(ContextResolver):
+    """Resolve context from the triggering event envelope attributes."""
+
+    def resolve(self, query: str, event: Any, params: dict[str, Any]) -> Any:
+        attributes = _event_attributes(event)
+        if query in {"", "attributes"}:
+            return attributes
+        if query.startswith("attributes."):
+            return _resolve_path(attributes, query.removeprefix("attributes."))
+        return _resolve_path(attributes, query)
+
+
+def _event_attributes(event: Any) -> dict[str, Any]:
+    if not isinstance(event, dict):
+        raise RuntimeError("event-payload source requires an event envelope")
+    attributes = event.get("attributes")
+    if not isinstance(attributes, dict):
+        raise RuntimeError("event-payload source requires envelope attributes")
+    return attributes
+
+
+def _resolve_path(root: dict[str, Any], path: str) -> Any:
+    if not path:
+        return root
+    current: Any = root
+    for part in path.split("."):
+        if not part:
+            return {}
+        if not isinstance(current, dict):
+            return {}
+        current = current.get(part)
+        if current is None:
+            return {}
+    return current
+
+
+CONTEXT_RESOLVER_REGISTRY["event-payload"] = EventPayloadContextResolver