1 files changed, 182 insertions, 0 deletions
diff --git a/src/features/layout/adapter/http.test.ts b/src/features/layout/adapter/http.test.ts
new file mode 100644
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+++ b/src/features/layout/adapter/http.test.ts
@@ -0,0 +1,182 @@
+import { DEFAULT_LAYOUT } from "@dispatch/layout-contract";
+import { describe, expect, it } from "vitest";
+import { createLayoutHttp } from "./http";
+
+/**
+ * Layout HTTP adapter tests — the OUTERMOST edge (fetch) is the only fake:
+ * a scripted `fetchImpl` returning canned Responses. No internal mocks.
+ */
+
+const LAYOUT_URL = "http://backend.test/workspaces/ws-a/layout";
+
+function fetchReturning(
+  status: number,
+  body: unknown,
+  capture?: { url?: string; init?: RequestInit | undefined },
+): typeof fetch {
+  return async (input: string | URL | Request, init?: RequestInit): Promise<Response> => {
+    if (capture !== undefined) {
+      capture.url =
+        typeof input === "string" ? input : input instanceof URL ? input.href : input.url;
+      capture.init = init;
+    }
+    return new Response(JSON.stringify(body), {
+      status,
+      headers: { "Content-Type": "application/json" },
+    });
+  };
+}
+
+describe("createLayoutHttp — getTree", () => {
+  it("GETs the well-known route and unwraps { tree }", async () => {
+    const capture: { url?: string; init?: RequestInit } = {};
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(200, { tree: DEFAULT_LAYOUT }, capture),
+    );
+    const result = await http.getTree("ws-a");
+    expect(result).toEqual({ ok: true, tree: DEFAULT_LAYOUT });
+    expect(capture.url).toBe(LAYOUT_URL);
+    expect(capture.init?.method).toBeUndefined(); // GET is the default
+  });
+
+  it("maps a 404 to the no-provider signal (notFound: true)", async () => {
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(404, { error: "No layout provider is active" }),
+    );
+    const result = await http.getTree("ws-a");
+    expect(result).toEqual({
+      ok: false,
+      notFound: true,
+      error: "No layout provider is active",
+    });
+  });
+
+  it("maps a 500 to a non-notFound failure carrying the body's error", async () => {
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(500, { error: "Layout storage failure" }),
+    );
+    const result = await http.getTree("ws-a");
+    expect(result).toEqual({ ok: false, notFound: false, error: "Layout storage failure" });
+  });
+
+  it("a network failure degrades to notFound (the no-provider mode)", async () => {
+    const http = createLayoutHttp("http://backend.test", async () => {
+      throw new TypeError("Failed to fetch");
+    });
+    const result = await http.getTree("ws-a");
+    expect(result.ok).toBe(false);
+    if (!result.ok) {
+      expect(result.notFound).toBe(true);
+      expect(result.error).toContain("Failed to fetch");
+    }
+  });
+
+  it("a malformed 200 (SPA-fallback JSON without a tree) degrades to notFound", async () => {
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(200, { chunks: [], historyEpoch: 0, latestSeq: 0 }),
+    );
+    const result = await http.getTree("ws-a");
+    expect(result).toMatchObject({ ok: false, notFound: true });
+  });
+});
+
+describe("createLayoutHttp — putTree", () => {
+  it("PUTs { tree } as JSON and unwraps the echo", async () => {
+    const capture: { url?: string; init?: RequestInit } = {};
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(200, { tree: DEFAULT_LAYOUT }, capture),
+    );
+    const result = await http.putTree("ws-a", DEFAULT_LAYOUT);
+    expect(result).toEqual({ ok: true, tree: DEFAULT_LAYOUT });
+    expect(capture.init?.method).toBe("PUT");
+    expect(capture.init?.body).toBe(JSON.stringify({ tree: DEFAULT_LAYOUT }));
+  });
+
+  it("maps a 400 { error } to a validation failure (not notFound)", async () => {
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(400, { error: "root: split has no children" }),
+    );
+    const result = await http.putTree("ws-a", DEFAULT_LAYOUT);
+    expect(result).toEqual({
+      ok: false,
+      notFound: false,
+      error: "root: split has no children",
+    });
+  });
+
+  it("maps a 404 to the no-provider signal", async () => {
+    const http = createLayoutHttp("http://backend.test", fetchReturning(404, {}));
+    const result = await http.putTree("ws-a", DEFAULT_LAYOUT);
+    expect(result).toMatchObject({ ok: false, notFound: true });
+  });
+});
+
+describe("createLayoutHttp — deleteTree", () => {
+  it("DELETEs and unwraps the fresh seed", async () => {
+    const capture: { url?: string; init?: RequestInit } = {};
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(200, { tree: DEFAULT_LAYOUT }, capture),
+    );
+    const result = await http.deleteTree("ws-a");
+    expect(result).toEqual({ ok: true, tree: DEFAULT_LAYOUT });
+    expect(capture.init?.method).toBe("DELETE");
+  });
+
+  it("maps a 404 to the no-provider signal", async () => {
+    const http = createLayoutHttp("http://backend.test", fetchReturning(404, {}));
+    const result = await http.deleteTree("ws-a");
+    expect(result).toMatchObject({ ok: false, notFound: true });
+  });
+});
+
+describe("createLayoutHttp — postOps (plan 04 §4.2)", () => {
+  it("POSTs { ops } to the ops route and unwraps { tree, applied }", async () => {
+    const capture: { url?: string; init?: RequestInit } = {};
+    const ops = [{ type: "ensurePanel", panels: "side", view: "demo" }] as const;
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(200, { tree: DEFAULT_LAYOUT, applied: 1 }, capture),
+    );
+    const result = await http.postOps("ws-a", ops);
+    expect(result).toEqual({ ok: true, tree: DEFAULT_LAYOUT, applied: 1 });
+    expect(capture.url).toBe(`${LAYOUT_URL}/ops`);
+    expect(capture.init?.method).toBe("POST");
+    expect(capture.init?.body).toBe(JSON.stringify({ ops }));
+  });
+
+  it("maps a 404 to the typed no-provider error (the ABI's documented failure)", async () => {
+    const http = createLayoutHttp("http://backend.test", fetchReturning(404, {}));
+    const result = await http.postOps("ws-a", []);
+    expect(result).toEqual({ ok: false, error: "no layout provider active" });
+  });
+
+  it("maps a 400 { error, failedOp } to the atomic-reject failure", async () => {
+    const http = createLayoutHttp(
+      "http://backend.test",
+      fetchReturning(400, { error: "op 1: no such node", failedOp: 1 }),
+    );
+    const result = await http.postOps("ws-a", [{ type: "removeNode", target: "x" }]);
+    expect(result).toEqual({ ok: false, error: "op 1: no such node", failedOp: 1 });
+  });
+
+  it("a malformed 200 (no tree in the body) is a failure, never a silent ok", async () => {
+    const http = createLayoutHttp("http://backend.test", fetchReturning(200, { applied: 2 }));
+    const result = await http.postOps("ws-a", []);
+    expect(result).toMatchObject({ ok: false });
+  });
+
+  it("a network failure degrades to a typed failure (never throws)", async () => {
+    const http = createLayoutHttp("http://backend.test", async () => {
+      throw new TypeError("fetch failed");
+    });
+    const result = await http.postOps("ws-a", []);
+    expect(result).toEqual({ ok: false, error: "fetch failed" });
+  });
+});