feat(cases): accept replay-safe ticket escalations

README.md

@@ -26,7 +26,10 @@ The executable backend slice now exposes:
   assignment/evidence/Decision/record references, and replay-safe lifecycle
   events; and
 - `cases.service_launcher`, which opens exactly one deterministic case from an
-  exact published Service revision and safely replays the same Portal launch.
+  exact published Service revision and safely replays the same Portal launch;
+  and
+- `tickets.case_escalation`, which creates exactly one formal Case from an
+  authorized Ticket handoff while preserving a governed Ticket reference.
 
 Cases does not own institutional Service, Party, representation, identity,
 address, Mandate, Decision, file, workflow, or task lifecycles. The `/cases`
@@ -50,3 +53,14 @@ Historical case evidence is retained; current open case and active access facts
 require authorized manual review through the existing lifecycle. Applicant
 identity correlation remains a Parties responsibility and is never guessed
 from a case's party references.
+
+## Ticket escalation
+
+When Tickets requests escalation, Cases rechecks tenant membership and
+`cases:case:create`, resolves the exact active Case type and its initial status,
+and derives a deterministic Case ID from the Ticket and idempotency key. A retry
+returns the same Case. The Case keeps only the stable Ticket reference, source
+revision, number, and authorized handoff note in governed context; it does not
+copy Ticket comments, attachments, participants, or lifecycle state. If Cases
+is absent or the configured type is unavailable, Tickets remains usable and
+shows the integration consequence to the operator.