feat: workstream attachments at creation time + SDK + UI parity (#362)

* feat: workstream attachments at creation time + SDK + UI parity

Closes the two big deferred items from PR #356: attaching files as part
of the initial workstream-creation request, and full SDK coverage of the
attachment surface.

Server: POST /v1/api/workstreams/new now accepts multipart/form-data
(meta JSON + 0..N file parts).  Files are validated and saved as pending
under the new ws; when initial_message is also set the create handler
reserves them onto that turn before the dispatch worker fires, mirroring
the /v1/api/send pattern.  Validation failure rolls back the workstream
via delete_workstream so we don't leak orphan rows or emit a phantom
ws_created/ws_closed pair on SSE.  JSON path is unchanged.

Console routing: route_create accepts multipart with ?ws_id=<hex> as a
query parameter (the console hashes the id before the body lands).
Added /v1/api/route/workstreams/{ws_id}/attachments POST/GET/DELETE +
.../{attachment_id}/content GET proxies that forward raw bytes and
preserve upstream headers (Content-Disposition, X-Content-Type-Options,
CSP sandbox).

Python + TypeScript SDKs: AttachmentUpload type, upload_attachment,
list_attachments, get_attachment_content, delete_attachment, and
send(attachment_ids=...).  create_workstream(attachments=...) sends
multipart and pre-generates a ws_id client-side so cluster routing
works.  SDKs reject attachments+target_node combinations since the
multipart route doesn't honor target_node.

Web UI: dashboard composer refactored to a single unified create flow.
Replaced the inconsistent split (Enter created+sent raw, "New Chat"
opened a modal) with one rich composer carrying a textarea, paperclip
+ chip strip, drag-drop, paste-image, and a collapsible Options panel
for model/judge_model/skill.  Submit button dynamically labels Create
vs Send.  New-workstream modal also gained the same paperclip + chip
strip + first-message field for the tab-bar + entry point.

Tests: 30 new tests across server multipart create, console route
multipart + attachment proxies, Python + TS SDK attachment surfaces,
plus regressions for the three review-flagged bugs (Content-Type
boundary preservation, attachments+target_node rejection, no phantom
ws_created on validation failure).

* fix: address Copilot review feedback on PR #362

- web_helpers: docstring now matches behaviour — read_multipart_create_or_400
  does enforce the optional max_per_file_bytes cap as defense-in-depth.
- app.js: drop the duplicated _formatAttachSize definition (one already
  exists earlier for pane chips); add a shared _isAttachmentAllowed helper
  that mirrors the server's classifier (png/jpeg/gif/webp images, text/*
  MIMEs, allowlisted application/* MIMEs, known text extensions) and call
  it from both _newWsAddFiles and _addDashboardFiles so unsupported files
  fail fast client-side instead of after a server roundtrip.
- app.js: dashboardSubmit catch now suppresses the redundant error toast
  on authFetch's "auth" Error and falls back to a generic message when
  err.message is undefined, instead of rendering "Connection error: undefined".
- SendResponse (Pydantic + TS): document and expose attached_ids,
  dropped_attachment_ids, priority, and msg_id so attachment-aware SDK
  callers can detect partial reservations and dequeue queued messages.
- test_server_attachments_on_create: drop the dual `import turnstone.server`
  + `from turnstone.server import` style — use monkeypatch.setattr by
  dotted path for module-level mutation and `from … import …` for the
  helpers, keeping a single import style.

sdk/typescript/tests/console.test.ts

@@ -62,6 +62,28 @@ describe("TurnstoneConsole", () => {
     expect(url).toContain("page=2");
   });
 
+  it("routeCreateWorkstream rejects attachments + target_node", async () => {
+    const fetchFn = vi.fn().mockResolvedValue(
+      new Response("{}", {
+        status: 500,
+        headers: { "content-type": "application/json" },
+      }),
+    );
+    const client = new TurnstoneConsole({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const data = new TextEncoder().encode("hi");
+    await expect(
+      client.routeCreateWorkstream({
+        name: "x",
+        target_node: "n1",
+        attachments: [{ filename: "a.txt", data }],
+      }),
+    ).rejects.toThrow(/target_node/);
+    expect(fetchFn).not.toHaveBeenCalled();
+  });
+
   it("health returns parsed response", async () => {
     const fetchFn = mockFetch({
       status: "ok",

sdk/typescript/tests/server-attachments.test.ts

@@ -0,0 +1,168 @@
+import { describe, expect, it, vi } from "vitest";
+import { TurnstoneServer } from "../src/server.js";
+
+function mockFetch(response: object, status = 200): typeof globalThis.fetch {
+  return vi.fn().mockResolvedValue(
+    new Response(JSON.stringify(response), {
+      status,
+      headers: { "content-type": "application/json" },
+    }),
+  );
+}
+
+function mockFetchBytes(
+  body: Uint8Array,
+  contentType: string,
+  filename = "",
+): typeof globalThis.fetch {
+  const headers: Record<string, string> = { "content-type": contentType };
+  if (filename)
+    headers["content-disposition"] = `inline; filename="${filename}"`;
+  return vi
+    .fn()
+    .mockResolvedValue(new Response(body, { status: 200, headers }));
+}
+
+describe("TurnstoneServer attachments", () => {
+  it("uploadAttachment sends multipart with filename", async () => {
+    const fetchFn = mockFetch({
+      attachment_id: "att-1",
+      filename: "a.txt",
+      mime_type: "text/plain",
+      size_bytes: 5,
+      kind: "text",
+    });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const data = new TextEncoder().encode("hello");
+    const result = await client.uploadAttachment("ws-X", {
+      filename: "a.txt",
+      data,
+      mimeType: "text/plain",
+    });
+    expect(result.attachment_id).toBe("att-1");
+
+    const [url, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(url).toBe("http://test/v1/api/workstreams/ws-X/attachments");
+    expect(init.method).toBe("POST");
+    expect(init.body).toBeInstanceOf(FormData);
+    // Browser/Node fetch sets the Content-Type header from FormData itself
+    expect(init.headers["Content-Type"]).toBeUndefined();
+  });
+
+  it("listAttachments hits the GET endpoint", async () => {
+    const fetchFn = mockFetch({ attachments: [] });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const resp = await client.listAttachments("ws-X");
+    expect(resp.attachments).toEqual([]);
+    const [url, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(url).toBe("http://test/v1/api/workstreams/ws-X/attachments");
+    expect(init.method).toBe("GET");
+  });
+
+  it("getAttachmentContent returns raw bytes + parsed headers", async () => {
+    const bytes = new TextEncoder().encode("hello world");
+    const fetchFn = mockFetchBytes(
+      bytes,
+      "text/plain; charset=utf-8",
+      "notes.md",
+    );
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const result = await client.getAttachmentContent("ws-X", "att-1");
+    expect(new TextDecoder().decode(result.bytes)).toBe("hello world");
+    expect(result.contentType).toBe("text/plain; charset=utf-8");
+    expect(result.filename).toBe("notes.md");
+  });
+
+  it("deleteAttachment hits the DELETE endpoint", async () => {
+    const fetchFn = mockFetch({ status: "deleted" });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const resp = await client.deleteAttachment("ws-X", "att-1");
+    expect(resp.status).toBe("deleted");
+    const [, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(init.method).toBe("DELETE");
+  });
+
+  it("send threads attachment_ids when provided", async () => {
+    const fetchFn = mockFetch({ status: "ok" });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    await client.send("hi", "ws-X", { attachmentIds: ["a1", "a2"] });
+    const [, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(JSON.parse(init.body)).toEqual({
+      message: "hi",
+      ws_id: "ws-X",
+      attachment_ids: ["a1", "a2"],
+    });
+  });
+
+  it("send omits attachment_ids when not supplied", async () => {
+    const fetchFn = mockFetch({ status: "ok" });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    await client.send("hi", "ws-X");
+    const [, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(JSON.parse(init.body)).toEqual({ message: "hi", ws_id: "ws-X" });
+  });
+
+  it("createWorkstream with attachments sends multipart and auto-generates ws_id", async () => {
+    const fetchFn = mockFetch({
+      ws_id: "00ff00000000000000000000000000ff",
+      name: "demo",
+      attachment_ids: ["att-1"],
+    });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    const data = new TextEncoder().encode("hello");
+    const resp = await client.createWorkstream({
+      name: "demo",
+      initial_message: "describe",
+      attachments: [{ filename: "a.txt", data, mimeType: "text/plain" }],
+    });
+    expect(resp.attachment_ids).toEqual(["att-1"]);
+
+    const [url, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(url).toBe("http://test/v1/api/workstreams/new");
+    expect(init.method).toBe("POST");
+    expect(init.body).toBeInstanceOf(FormData);
+
+    const form = init.body as FormData;
+    const meta = JSON.parse(form.get("meta") as string);
+    expect(meta.name).toBe("demo");
+    expect(meta.initial_message).toBe("describe");
+    expect(meta.ws_id).toMatch(/^[0-9a-f]{32}$/);
+    expect(meta.attachments).toBeUndefined();
+
+    const file = form.get("file");
+    expect(file).toBeInstanceOf(Blob);
+  });
+
+  it("createWorkstream without attachments uses JSON body", async () => {
+    const fetchFn = mockFetch({ ws_id: "ws-json", name: "j" });
+    const client = new TurnstoneServer({
+      baseUrl: "http://test",
+      fetch: fetchFn,
+    });
+    await client.createWorkstream({ name: "j" });
+    const [, init] = (fetchFn as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(init.headers["Content-Type"]).toBe("application/json");
+    expect(JSON.parse(init.body)).toEqual({ name: "j" });
+  });
+});