Keep warm sessions across project revision transitions (#17461)

server/src/services/heartbeat/workspaces.ts

@@ -2800,6 +2800,7 @@ function buildSessionConfigCategoryValues(input: {
   // the timestamp here makes every comment invalidate an otherwise reusable
   // task session.
   delete workspaceConfig.issueConfigRevisionAt;
+  delete workspaceConfig.projectConfigRevisionAt;
   // This row is runtime state, not requested configuration. It is absent
   // before the first reusable run is realized and present on the next turn;
   // fingerprinting that transition would rotate the native session exactly