feat(confidence-engine): v0.60e route investigation identity

Migrate the Investigation page route to own durable investigation identity
via its route [id] segment, passing that ID through to ScenarioForm for
hydration and persistence.

- Remove hardcoded INVESTIGATION_ID constant from page.jsx
- Use params.id as routeId; loadInvestigation(routeId) loads by identity
- Pass investigationId prop into ScenarioForm in both branch paths
- Session restore calls loadInvestigation(investigationId)
- All 4 save call sites include id: investigationId in snapshot
- Missing identified Investigation starts clean (no singleton fallback)
- Legacy singleton is not migrated/fallback-loaded
- Portfolio remains unmigrated; Report remains unmigrated; Restart untouched

Deterministic tests: 34/34 pass (scenario-form-persistence + investigation-storage)
Build: PASS
Live Playwright: all criteria verified at /investigations/v060e-live

app/investigations/[id]/page.jsx

@@ -4,18 +4,18 @@ import React from "react";
 import { loadInvestigation } from "@/lib/storage/investigation-storage";
 import ScenarioForm from "@/components/scenario-form";
 import Link from "next/link";
-import { useRouter } from "next/navigation";
+import { useParams, useRouter } from "next/navigation";
 import { useEffect, useState } from "react";
 
-const INVESTIGATION_ID = "case-1";
+export default function InvestigationPage({ params }) {
-
-export default function InvestigationPage() {
   const router = useRouter();
+  const routeId = typeof params?.id === "string" ? params.id : "";
   const [existing, setExisting] = useState(null);
 
   useEffect(() => {
-    setExisting(loadInvestigation());
+    if (!routeId) return;
-  }, []);
+    setExisting(loadInvestigation(routeId));
+  }, [routeId]);
 
   return (
     <main className="mx-auto max-w-[1600px] px-6 py-12">
@@ -37,12 +37,14 @@ export default function InvestigationPage() {
       </p>
       {existing ? (
         <ScenarioForm
+          investigationId={routeId}
           existingSnapshot={existing}
-          onNavigateToReport={() => router.push(`/investigations/${INVESTIGATION_ID}/report`)}
+          onNavigateToReport={() => router.push(`/investigations/${routeId}/report`)}
         />
       ) : (
         <ScenarioForm
-          onNavigateToReport={() => router.push(`/investigations/${INVESTIGATION_ID}/report`)}
+          investigationId={routeId}
+          onNavigateToReport={() => router.push(`/investigations/${routeId}/report`)}
         />
       )}
     </main>

components/scenario-form.jsx

@@ -271,7 +271,7 @@ export async function executeEpisodeDone({
   return { success: true, nextGraph, synthesisResult };
 }
 
-export default function ScenarioForm({ onNavigateToReport }) {
+export default function ScenarioForm({ investigationId, onNavigateToReport }) {
   const [scenario, setScenario] = useState("");
   const [status, setStatus] = useState("idle"); // idle | loading | error | success
   const [result, setResult] = useState(null);
@@ -476,6 +476,7 @@ export default function ScenarioForm({ onNavigateToReport }) {
 
         // Trigger autosave to persist the report
         void saveInvestigation({
+          id: investigationId,
           scenario,
           situationGraph: result.situationGraph,
           selectedQuestion: result.selectedQuestion,
@@ -543,7 +544,7 @@ export default function ScenarioForm({ onNavigateToReport }) {
   /* Restore persisted session on mount ─────────── */
   useEffect(() => {
     if (typeof window === "undefined") return;
-    const saved = loadInvestigation();
+    const saved = investigationId ? loadInvestigation(investigationId) : null;
     if (!saved) return;
 
     const hasGraph = Boolean(saved.situationGraph);
@@ -580,6 +581,7 @@ export default function ScenarioForm({ onNavigateToReport }) {
     if (!result?.situationGraph) return;
 
     void saveInvestigation({
+      id: investigationId,
       scenario,
       situationGraph: result.situationGraph,
       selectedQuestion: result.selectedQuestion,
@@ -678,7 +680,7 @@ export default function ScenarioForm({ onNavigateToReport }) {
         setResult(normalised);
         /* ── v0.59a — provenance: first meaningful change sets revision to 1 ── */
         setInvestigationRevision(1);
-        saveInvestigation({ scenario, situationGraph: normalised.situationGraph, selectedQuestion: normalised.selectedQuestion, summary: data.summary ?? null, updatedAt: new Date().toISOString(), focusedContributions, findings: [], investigationReport, investigationRevision: 1 });
+        saveInvestigation({ id: investigationId, scenario, situationGraph: normalised.situationGraph, selectedQuestion: normalised.selectedQuestion, summary: data.summary ?? null, updatedAt: new Date().toISOString(), focusedContributions, findings: [], investigationReport, investigationRevision: 1 });
       } else {
         setStatus("error");
         setCurrentUnderstanding(data.summary ?? null);
@@ -765,7 +767,7 @@ export default function ScenarioForm({ onNavigateToReport }) {
         /* ── v0.59a — provenance: meaningful change advances revision ── */
         const nextRev = (investigationRevision ?? 0) + 1;
         setInvestigationRevision(nextRev);
-        saveInvestigation({ scenario, situationGraph: nextGraph, selectedQuestion: normaliseUpdateSelectedQuestion(outcome.selectedQuestion), summary: currentUnderstanding, updatedAt: new Date().toISOString(), focusedContributions, findings: nextFindings, investigationReport, investigationRevision: nextRev });
+        saveInvestigation({ id: investigationId, scenario, situationGraph: nextGraph, selectedQuestion: normaliseUpdateSelectedQuestion(outcome.selectedQuestion), summary: currentUnderstanding, updatedAt: new Date().toISOString(), focusedContributions, findings: nextFindings, investigationReport, investigationRevision: nextRev });
       } else {
         setUpdateStatus("error");
         setUpdateError(outcome);

docs/current-handoff.md

@@ -381,7 +381,42 @@ Migrate existing application callers to the identity-aware contract signatures:
 
 **Status:** UI/routes are **not** migrated. All existing callers continue via the singleton compatibility path (they call `saveInvestigation({ ... })` with no explicit second parameter, and their snapshots carry no `id` field). No production caller was modified in this increment.
 
-**Next restart point:** Caller migration — update application consumers to pass investigation ID through save calls so canonical identity-aware semantics activate for all writes.
+## v0.60e — Route-Owned Investigation Identity
+
+**Purpose:** Migrate the Investigation page route to own durable investigation identity via its route `[id]` segment, passing that ID through to ScenarioForm for hydration and persistence without migrating legacy singleton data or changing Portfolio/Report behaviour.
+
+### What was implemented
+
+| File | Change |
+|---|---|
+| `app/investigations/[id]/page.jsx` | Removed hardcoded `INVESTIGATION_ID = "case-1"` constant; route `[id]` param extracted as `routeId` via `params.id`; `loadInvestigation(routeId)` loads by route identity; `investigationId={routeId}` passed to ScenarioForm in both branch paths; report navigation uses `routeId`. |
+| `components/scenario-form.jsx` | Added `investigationId` prop; session restore calls `loadInvestigation(investigationId)` when provided; all 4 save call sites include `id: investigationId` in snapshot (autosave effect, start-case submit, update-case submit, report overview autosave). |
+
+### Contract crossings verified by deterministic test
+
+- **Owning test files:** `tests/storage/scenario-form-persistence.test.js` (11 tests) + `tests/storage/investigation-storage.test.js` (23 tests, including v0.60d canonical identity section)
+- All 34 tests pass on first run; no reruns required
+
+### Verified behaviour
+
+- Route ID is passed from `[id]/page.jsx` into ScenarioForm as `investigationId`: **YES**
+- Missing identified Investigation (`loadInvestigation("v060e-live")` → null) starts clean: **YES**
+- Legacy singleton fallback used: **NO** — no backward-compat load was needed; the route ID was absent from storage
+- First meaningful saved snapshot carries route ID: **YES** (all 4 save sites inject `id: investigationId`)
+- Subsequent save identity preserved: **YES** (storage layer uses `snapshot.id` as sole identity authority)
+- Storage provider changed: **NO** — only `investigation-storage.js` wrapper, already-proved in v0.60d
+
+### Portfolio
+
+Not migrated. `app/page.jsx` retains hardcoded `INVESTIGATION_ID = "case-1"`. Create New navigation to a durable-ID route is later work.
+
+### Report
+
+Not migrated. `app/investigations/[id]/report/page.jsx` untouched. Remains a later caller migration increment.
+
+### Restart
+
+Untouched in this increment. All `clearInvestigation()` calls remain without an id argument (legacy singleton path). If identity-aware restart is needed, the next increment should pass `investigationId` through those clear calls.
 
 ## Next implementation boundary