fix(dispatch): publish to /dispatch/envelopes with event-card profile (doc 23)

The client posted a body-only envelope to {DISPATCH_API_URL}/messages — an
endpoint that does not exist. Now: /dispatch/envelopes, mandatory DispatchCard
block per the platform pydantic model (int schema_version=1/state_code=0,
task_id=0, int4-safe epoch-second sequence_number), payload under card.event,
UUID card_uid (stable uuid5 for ULID-style asset ids). Inbox accepts both
card.event and legacy root body.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/integrations/dispatch_client.py

@@ -17,6 +17,7 @@ Design notes:
 
 from __future__ import annotations
 
+import time
 import uuid
 from datetime import UTC, datetime
 from typing import Any
@@ -40,6 +41,16 @@ def deterministic_event_id(*parts: Any) -> str:
     return str(uuid.uuid5(_DISPATCH_NAMESPACE, ":".join(str(p) for p in parts)))
 
 
+def _card_uid(value: str) -> str:
+    """Envelope card_uid must be a UUID (dispatch_api/models.py). Business ids
+    that are already UUIDs pass through; ULID-style asset ids map to a stable
+    uuid5 so re-emits keep the same card."""
+    try:
+        return str(uuid.UUID(str(value)))
+    except ValueError:
+        return str(uuid.uuid5(_DISPATCH_NAMESPACE, str(value)))
+
+
 def build_envelope(
     message_type: str,
     card_uid: str,
@@ -49,15 +60,37 @@ def build_envelope(
     message_id: str | None = None,
     created_at: str | None = None,
 ) -> dict[str, Any]:
-    """Build the dispatch JSON envelope (INTER_MODULE_CONTRACT §2.4)."""
+    """Build the dispatch JSON envelope (02 §2.4 + platform doc 23 profile).
+
+    The card block mirrors the mandatory DispatchCard fields of the platform
+    pydantic model (dispatch_api/models.py): int schema_version/state_code,
+    task_id 0 for out-of-ticket events, int4-safe epoch-second
+    sequence_number; the event payload nests under card.event untouched.
+    """
+    now = created_at or datetime.now(tz=UTC).isoformat()
+    uid = _card_uid(card_uid)
     return {
         "message_id": message_id or str(uuid.uuid4()),
         "event_id": event_id or str(uuid.uuid4()),
-        "card_uid": str(card_uid),
+        "card_uid": uid,
+        "task_id": 0,
         "message_type": message_type,
         "participant_code": settings.dispatch_participant_code,
-        "created_at": created_at or datetime.now(tz=UTC).isoformat(),
-        "body": body,
+        "created_at": now,
+        "card": {
+            "schema_version": 1,
+            "card_uid": uid,
+            "task_id": 0,
+            "sequence_number": int(time.time()),
+            "created_at": now,
+            "updated_at": now,
+            "state_code": 0,
+            "specialist_status": "n/a",
+            "event": body,
+        },
+        "media_files": [],
+        "media_file_count": 0,
+        "local_delivery_status": {},
     }
 
 
@@ -80,7 +113,7 @@ def publish(
     envelope = build_envelope(message_type, card_uid, body, event_id=event_id)
     try:
         res = httpx.post(
-            f"{settings.dispatch_api_url.rstrip('/')}/messages",
+            f"{settings.dispatch_api_url.rstrip('/')}/dispatch/envelopes",
             json=envelope,
             headers={"X-API-Key": settings.dispatch_api_key},
             timeout=settings.dispatch_timeout_seconds,
@@ -172,7 +205,10 @@ def handle_inbox_message(envelope: dict[str, Any]) -> dict[str, Any]:
 
     event_id = str(envelope.get("event_id") or "")
     message_type = str(envelope.get("message_type") or "")
-    body = envelope.get("body") or {}
+    # Doc 23 profile nests the payload under card.event; legacy senders used a
+    # root-level body. Accept both at this external boundary.
+    card = envelope.get("card") or {}
+    body = card.get("event") or envelope.get("body") or {}
 
     with session_scope() as db:
         already = db.execute(