feat(confidence-engine): v0.60c identity-aware investigation storage

- loadInvestigation(id) selects by durable ID when provided, null for unknown
- saveInvestigation(snapshot, id) persists under provider-chosen key derived from id
- clearInvestigation(id) removes specific investigation by identity when provided
- localStorage representation: confidence-engine-investigation:<durable-id>
- Backward-compatible singleton path preserved for existing unmigrated callers
- 6 new targeted tests proving two independently addressable Investigations

tests/storage/investigation-storage.test.js

@@ -226,3 +226,110 @@ describe("investigation-storage provider", () => {
   });
 
 });
+
+// ── v0.60c — identity-aware multi-investigation persistence ────────────
+
+describe("investigation-storage v0.60c identity-aware", () => {
+
+  function newId() {
+    return `inv-${Math.random().toString(36).slice(2, 9)}`;
+  }
+
+  beforeEach(() => {
+    globalThis.window.localStorage.clear();
+  });
+
+  // ── A: saveInvestigation(A) persists A under A.id ───────────────
+
+  it("save with id persists under that id key", async () => {
+    const { load, save } = await getModule();
+    const idA = newId();
+    const snapA = makeSnapshot({ id: idA, title: "Alpha" });
+
+    save(snapA, idA);
+
+    const loaded = load(idA);
+    expect(loaded).not.toBeNull();
+    expect(loaded.id).toBe(idA);
+    expect(loaded.title).toBe("Alpha");
+  });
+
+  // ── B: saveInvestigation(B) persists B independently under B.id ──
+
+  it("save two investigations with different ids are independent", async () => {
+    const { load, save } = await getModule();
+    const idA = newId();
+    const idB = newId();
+    const snapA = makeSnapshot({ id: idA, title: "Alpha" });
+    const snapB = makeSnapshot({ id: idB, title: "Beta" });
+
+    save(snapA, idA);
+    save(snapB, idB);
+
+    // A survives B save
+    const loadedA = load(idA);
+    expect(loadedA).not.toBeNull();
+    expect(loadedA.id).toBe(idA);
+    expect(loadedA.title).toBe("Alpha");
+  });
+
+  // ── A loads by A.id ──────────────────────────────────────────────
+
+  it("loadInvestigation(A.id) returns A", async () => {
+    const { load, save } = await getModule();
+    const idA = newId();
+    const snapA = makeSnapshot({ id: idA, title: "Alpha" });
+    save(snapA, idA);
+
+    const loaded = load(idA);
+    expect(loaded).not.toBeNull();
+    expect(loaded.id).toBe(idA);
+    expect(loaded.title).toBe("Alpha");
+  });
+
+  // ── B loads by B.id ──────────────────────────────────────────────
+
+  it("loadInvestigation(B.id) returns B", async () => {
+    const { load, save } = await getModule();
+    const idA = newId();
+    const idB = newId();
+    const snapA = makeSnapshot({ id: idA, title: "Alpha" });
+    const snapB = makeSnapshot({ id: idB, title: "Beta" });
+
+    save(snapA, idA);
+    save(snapB, idB);
+
+    const loaded = load(idB);
+    expect(loaded).not.toBeNull();
+    expect(loaded.id).toBe(idB);
+    expect(loaded.title).toBe("Beta");
+  });
+
+  // ── unknown ID returns null ──────────────────────────────────────
+
+  it("loadInvestigation(unknownId) returns null", async () => {
+    const { load } = await getModule();
+    const loaded = load("non-existent-id-xyz");
+    expect(loaded).toBeNull();
+  });
+
+  // ── save does not invent or change the supplied ID ───────────────
+
+  it("saveInvestigation does not invent or replace the supplied id", async () => {
+    const { save } = await getModule();
+    const originalId = `inv-unique-77`;
+    const snapA = makeSnapshot({ id: originalId, title: "Alpha" });
+
+    save(snapA, originalId);
+
+    // Verify the persisted record still carries exactly the supplied id
+    // (the deep clone should not have mutated it)
+    const raw = globalThis.window.localStorage.getItem(
+      `confidence-engine-investigation:${originalId}`
+    );
+    expect(raw).not.toBeNull();
+    const parsed = JSON.parse(raw);
+    expect(parsed.id).toBe(originalId);
+  });
+
+});