feat(frontend): viewer humain fil-par-paire en lecture seule (LS7)

Frontend pur, lecture seule, consomme read_conversation_page (LS6) ; aucun changement backend.
- adapters : conversation.ts (gateway) + conversationNormalization.ts.
- features/conversations : useConversationThread, ConversationViewer, index.
- domain (types LS7), ports (port + Gateways.conversation), adapters/index, mock (+ clé inventaire).
- features/workstate : ProjectWorkStatePanel prop onOpenConversation.
- features/projects : ProjectsView swap viewer.
- tests (QA, verts) : conversationNormalization, mock/conversationGateway,
  useConversationThread, ConversationViewer, ProjectsView.ls7. tsc 0, vitest 443/443 (+36).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/adapters/conversationNormalization.test.ts

@@ -0,0 +1,164 @@
+/**
+ * LS7 — wire → domain normalization for the conversation transcript read, and the
+ * `TauriConversationGateway.readPage` argument shape (single flat `request`).
+ */
+import { describe, it, expect, vi, beforeEach } from "vitest";
+
+import { normalizeTurnPage } from "./conversationNormalization";
+
+const invokeMock = vi.fn();
+vi.mock("@tauri-apps/api/core", () => ({
+  invoke: (...args: unknown[]) => invokeMock(...args),
+}));
+
+describe("normalizeTurnPage", () => {
+  it("maps a full camelCase TurnPageDto to the domain TurnPage", () => {
+    const page = normalizeTurnPage({
+      turns: [
+        {
+          id: "t1",
+          atMs: 1_700_000_000_000,
+          role: "prompt",
+          source: { kind: "human" },
+          text: "bonjour",
+          textLen: 7,
+        },
+        {
+          id: "t2",
+          atMs: 1_700_000_000_500,
+          role: "response",
+          source: { kind: "agent", agentId: "agent-7" },
+          text: "réponse complète",
+          textLen: 16,
+        },
+        {
+          id: "t3",
+          atMs: 1_700_000_001_000,
+          role: "toolActivity",
+          source: { kind: "agent", agentId: "agent-7" },
+          text: "tool run",
+          textLen: 8,
+        },
+      ],
+      hasMore: true,
+      nextAnchor: "t3",
+    });
+
+    expect(page.hasMore).toBe(true);
+    expect(page.nextAnchor).toBe("t3");
+    expect(page.turns).toHaveLength(3);
+    expect(page.turns[0]).toEqual({
+      id: "t1",
+      atMs: 1_700_000_000_000,
+      role: "prompt",
+      source: { kind: "human" },
+      text: "bonjour",
+      textLen: 7,
+    });
+    // source.kind mapping: agent carries the agentId.
+    expect(page.turns[1].source).toEqual({ kind: "agent", agentId: "agent-7" });
+    // The three roles round-trip verbatim.
+    expect(page.turns.map((t) => t.role)).toEqual([
+      "prompt",
+      "response",
+      "toolActivity",
+    ]);
+  });
+
+  it("preserves the full (unbounded) turn text", () => {
+    const big = "Z".repeat(40_000);
+    const page = normalizeTurnPage({
+      turns: [{ id: "t1", atMs: 1, role: "response", source: { kind: "human" }, text: big, textLen: 40_000 }],
+      hasMore: false,
+    });
+    expect(page.turns[0].text).toHaveLength(40_000);
+    expect(page.turns[0].textLen).toBe(40_000);
+  });
+
+  it("omits nextAnchor when absent and defaults hasMore to false", () => {
+    const page = normalizeTurnPage({ turns: [] });
+    expect(page.turns).toEqual([]);
+    expect(page.hasMore).toBe(false);
+    expect("nextAnchor" in page).toBe(false);
+  });
+
+  it("degrades defensively on a malformed payload (never throws)", () => {
+    const page = normalizeTurnPage({
+      turns: [{ id: 42, role: "weird", source: { kind: "ghost" } }, null, "nope"],
+      hasMore: "yes",
+      nextAnchor: 99,
+    });
+    // hasMore only true on a strict boolean; non-string nextAnchor dropped.
+    expect(page.hasMore).toBe(false);
+    expect("nextAnchor" in page).toBe(false);
+    // Unknown role ⇒ "prompt"; non-record source ⇒ human; missing text ⇒ "".
+    expect(page.turns[0].role).toBe("prompt");
+    expect(page.turns[1].source).toEqual({ kind: "human" });
+    expect(page.turns[0].text).toBe("");
+    // An unknown source.kind degrades to human.
+    expect(page.turns[0].source).toEqual({ kind: "human" });
+  });
+
+  it("returns an empty page for a non-object payload", () => {
+    expect(normalizeTurnPage(null)).toEqual({ turns: [], hasMore: false });
+    expect(normalizeTurnPage(undefined)).toEqual({ turns: [], hasMore: false });
+  });
+});
+
+describe("TauriConversationGateway.readPage", () => {
+  beforeEach(() => {
+    invokeMock.mockReset();
+  });
+
+  it("invokes read_conversation_page with a single flat request, default direction backward", async () => {
+    invokeMock.mockResolvedValue({ turns: [], hasMore: false });
+    const { TauriConversationGateway } = await import("./conversation");
+    const gw = new TauriConversationGateway();
+
+    await gw.readPage("proj-1", "conv-1");
+
+    expect(invokeMock).toHaveBeenCalledTimes(1);
+    const [command, args] = invokeMock.mock.calls[0];
+    expect(command).toBe("read_conversation_page");
+    // Single `request` argument with FLAT fields (no nested `cursor`).
+    expect(args).toEqual({
+      request: {
+        projectId: "proj-1",
+        conversationId: "conv-1",
+        anchor: undefined,
+        direction: "backward",
+        limit: undefined,
+      },
+    });
+  });
+
+  it("forwards anchor/direction/limit and normalizes the result", async () => {
+    invokeMock.mockResolvedValue({
+      turns: [{ id: "t9", atMs: 5, role: "response", source: { kind: "human" }, text: "ok", textLen: 2 }],
+      hasMore: true,
+      nextAnchor: "t9",
+    });
+    const { TauriConversationGateway } = await import("./conversation");
+    const gw = new TauriConversationGateway();
+
+    const page = await gw.readPage("p", "c", {
+      anchor: "t5",
+      direction: "forward",
+      limit: 25,
+    });
+
+    expect(invokeMock.mock.calls[0][1]).toEqual({
+      request: {
+        projectId: "p",
+        conversationId: "c",
+        anchor: "t5",
+        direction: "forward",
+        limit: 25,
+      },
+    });
+    // Result is normalized to the domain TurnPage.
+    expect(page.turns[0].id).toBe("t9");
+    expect(page.nextAnchor).toBe("t9");
+    expect(page.hasMore).toBe(true);
+  });
+});