Fork assistant turns into new drafts (#1788)

* feat(chat): fork assistant turns into new drafts

Builds chat-history attachments on the daemon and routes them into draft composers so users can continue an assistant turn in an existing workspace tab or New Workspace.

* fix(chat): clean up fork draft handling

* fix(chat): address fork draft review feedback

* fix(server): build fork context from bounded timeline

* fix(app): restore assistant turn footer in streams

* fix(app): preserve fork draft setup

* fix(app): tighten assistant fork footers

* fix(app): lock active fork draft handoff

* fix(app): preserve attachment-only draft retries

* fix(app): unify composer attachment scopes

* fix(app): align chat history attachment labels

* fix(app): centralize attachment pill content

* fix(app): trim fork context for workspace naming

packages/app/src/attachments/workspace-attachments-store.test.ts

@@ -2,7 +2,9 @@ import { describe, expect, it } from "vitest";
 import type { WorkspaceComposerAttachment } from "./types";
 import {
   appendWorkspaceAttachment,
+  buildDraftWorkspaceAttachmentScopeKey,
   buildWorkspaceAttachmentScopeKey,
+  collectWorkspaceAttachmentsForScopes,
   resetWorkspaceAttachmentsStore,
   useWorkspaceAttachmentsStore,
 } from "./workspace-attachments-store";
@@ -57,6 +59,24 @@ function contextAttachment(id: string): WorkspaceComposerAttachment {
   };
 }
 
+function chatHistoryAttachment(id: string, text = "Previous chat."): WorkspaceComposerAttachment {
+  return {
+    kind: "chat_history",
+    id,
+    attachment: {
+      type: "text",
+      mimeType: "text/plain",
+      contextKind: "chat_history",
+      title: "Chat history",
+      text,
+    },
+    source: {
+      serverId: "local",
+      agentId: "agent-1",
+    },
+  };
+}
+
 describe("workspace attachments store", () => {
   it("scopes workspace attachments by server and workspace before cwd fallback", () => {
     expect(
@@ -76,6 +96,12 @@ describe("workspace attachments store", () => {
     ).toBe("workspace-attachments:server=local:cwd=%2Frepo");
   });
 
+  it("scopes draft attachments by draft id", () => {
+    expect(buildDraftWorkspaceAttachmentScopeKey("draft-1")).toBe(
+      "workspace-attachments:draft=draft-1",
+    );
+  });
+
   it("publishes and clears attachments for a workspace scope", () => {
     resetWorkspaceAttachmentsStore();
     const scopeKey = buildWorkspaceAttachmentScopeKey({
@@ -116,6 +142,13 @@ describe("workspace attachments store", () => {
     expect(appendWorkspaceAttachment([original], replacement)).toEqual([replacement]);
   });
 
+  it("dedupes repeated chat history attachments by id", () => {
+    const original = chatHistoryAttachment("chat_history:draft-1", "Original chat.");
+    const replacement = chatHistoryAttachment("chat_history:draft-1", "Updated chat.");
+
+    expect(appendWorkspaceAttachment([original], replacement)).toEqual([replacement]);
+  });
+
   it("adds a workspace attachment against the current scope state", () => {
     resetWorkspaceAttachmentsStore();
     const scopeKey = buildWorkspaceAttachmentScopeKey({
@@ -138,4 +171,25 @@ describe("workspace attachments store", () => {
       context,
     ]);
   });
+
+  it("collects attachments across requested scopes in scope order", () => {
+    const draftScopeKey = buildDraftWorkspaceAttachmentScopeKey("draft-1");
+    const workspaceScopeKey = buildWorkspaceAttachmentScopeKey({
+      serverId: "local",
+      workspaceId: "workspace-1",
+      cwd: "/repo",
+    });
+    const draftContext = chatHistoryAttachment("chat_history:draft-1");
+    const workspaceContext = contextAttachment("comment-1");
+
+    expect(
+      collectWorkspaceAttachmentsForScopes({
+        attachmentsByScope: {
+          [workspaceScopeKey]: [workspaceContext],
+          [draftScopeKey]: [draftContext],
+        },
+        scopeKeys: [` ${draftScopeKey} `, "", workspaceScopeKey],
+      }),
+    ).toEqual([draftContext, workspaceContext]);
+  });
 });