Merged PR 2257: refactor(representations): isolate finalisation boundary helpers (slice R8)

refactor(representations): isolate finalisation boundary helpers (slice R8)

Related work items: #22441

context/representations-refactor-tracker.md

@@ -321,6 +321,29 @@ Isolate submission logic.
 **Risk Level:** HIGH  
 (Must only be done after earlier slices stabilised)
 
+**Completion notes (this slice):**
+
+- Implemented on feature branch created from `refactor`: `rep-slice-r8-finalisation-boundary`.
+- Added a small representation-specific helper module:
+    - `components/case/representation/utils/finalisationBoundary.js`
+- Extracted only approved R8 seams:
+    - `buildRepresentationUpdateBody(...)` (pure shaping)
+    - `buildSubmitEnrichedValues(...)` (pure shaping)
+    - `runFinalisationSequence(...)` (ultra-thin orchestration wrapper)
+- Wired `components/case/representation/index.js` to use the new helpers while preserving parent-owned business branching.
+- Explicitly preserved R8 constraints:
+    - no completion-side-effect extraction from `representationComplete.js`
+    - no route/query changes
+    - no payload contract changes
+    - no validation logic changes
+    - no file upload/PDF/email behaviour changes
+    - no sequencing drift in finalisation success path
+
+**Validation evidence:**
+
+- `npm run lint` completed (warnings only, no new errors).
+- `npm run test:reps` completed: **7 passed (4.4m)**.
+
 ---
 
 ## Rules