refactor(breadcrumbs): map step-back route branches into renderer group

memory-bank/change-log.md

@@ -709,6 +709,51 @@ Follow-ups:
 - Next smaller slice candidate: add a focused helper test for empty-string/whitespace path lookups to assert strict null behavior for non-exact keys.
 - Next larger slice candidate: evaluate whether `/newappeal/[appealtypes]` and `/myportal/[appealtypes]` back-link branches can be extracted with explicit callback/setter injection while preserving state-step semantics.
 
+### CL-22541-W: breadcrumbs larger slice — step-back route-group extraction (`/newappeal/[appealtypes]`, `/myportal/[appealtypes]`)
+
+date: 2026-04-09  
+author: Cline  
+scope: `lib/routing/{breadcrumbRendererFactories,breadcrumbRouteMaps}.js`, `components/breadcrumbs.js`, `tests/phase22/{breadcrumb-route-maps-helper,breadcrumbs-route-map-structure}.test.cjs`  
+type: change  
+rationale: Execute the next larger extraction slice by moving step-based back-link branches into a dedicated mapped route group with explicit setter callback injection, preserving section-navigation semantics.
+impact: Structural refactor with preserved back-link and step-state behavior; no intended route/auth/session/API/EN-CY/a11y behavior change.
+status: completed
+
+Summary:
+
+- Added `createStepBackRouteRenderers(...)` in `lib/routing/breadcrumbRendererFactories.js` to map:
+    - `/newappeal/[appealtypes]`
+    - `/myportal/[appealtypes]`
+- Preserved existing step semantics in mapped handlers:
+    - no crumb when `currentSection <= 1`
+    - service-name crumb when `currentSection === 9999`
+    - back-link crumb with existing class parity (`govuk-breadcrumbs__link-item` for new-appeal flow)
+- Introduced explicit injected handlers (`onStepBack`, `onStepBackWithInlineClass`) and injected crumb renderer dependency (`renderBackCrumb`) into grouped factory composition.
+- Extended map builder in `lib/routing/breadcrumbRouteMaps.js` with `stepBackRouteRenderersByPath` and updated precedence order:
+    - simple -> link-text -> myportal -> new-appeal -> callback -> step-back -> case detail -> detail/account.
+- Updated `components/breadcrumbs.js`:
+    - pass `currentSection` and step-back callbacks into `createMappedRouteRendererGroups(...)`
+    - include step-back map in `buildBreadcrumbRendererMaps(...)`
+    - remove inline `isPath("/newappeal/[appealtypes]")` and `isPath("/myportal/[appealtypes]")` branches.
+- Expanded tests:
+    - `tests/phase22/breadcrumb-route-maps-helper.test.cjs`
+        - updated grouped map count/order to include step-back map (8 total)
+    - `tests/phase22/breadcrumbs-route-map-structure.test.cjs`
+        - assert step-back factory export + mapped route presence
+        - assert grouped destructuring includes step-back map
+        - assert inline step-back branches are removed
+        - assert updated map-order invariant includes step-back group.
+
+Validation:
+
+- `npx eslint lib/routing/breadcrumbRendererFactories.js lib/routing/breadcrumbRouteMaps.js components/breadcrumbs.js tests/phase22/breadcrumb-route-maps-helper.test.cjs tests/phase22/breadcrumbs-route-map-structure.test.cjs tests/phase22/index.test.cjs` -> pass.
+- `node tests/phase22/index.test.cjs` -> pass (combined suite).
+
+Follow-ups:
+
+- Next smaller slice candidate: add focused helper test for strict null behavior on empty-string/whitespace/non-exact path keys.
+- Next larger slice candidate: evaluate extractability of `/myportal/representation` back-link states via explicit callback injection, only if questionnaire/submit side-effects remain parity-safe and readable.
+
 ### CL-00X: 22500 `components/elements/index.js` Phase 1 helper extraction
 
 date: 2026-04-07