fix(agent): 输入草稿按会话保留,切换会话、关抽屉不丢

会话面板与新对话输入框的草稿原来是组件内状态,切到别的会话或 Esc 关抽屉就没了。
改为按会话(以及列表页 / 抽屉两处新对话)分键记在模块里,发送成功后清掉。

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

apps/web/app/components/agent/agent-drawer.tsx

@@ -13,6 +13,7 @@ import { Popover, PopoverContent, PopoverTrigger } from "~/components/ui/popover
 import { Sheet, SheetContent, SheetDescription, SheetHeader, SheetTitle } from "~/components/ui/sheet.tsx";
 import { errorMessage } from "~/lib/api.ts";
 import { capabilityMeta, isDenied, RunStatusBadge } from "./agent-conversation.tsx";
+import { DRAFT_DRAWER_GOAL, writeDraft } from "./agent-nav.ts";
 import { AgentRunPanel, GoalComposer } from "./agent-run-panel.tsx";
 import { AgentSessionList, drawerListMemory } from "./agent-session-list.tsx";
 import {
@@ -170,12 +171,16 @@ export function AgentDrawer() {
                   context={name}
                   onClearContext={clearAgentContext}
                   defaultGoal={context?.goal ?? ""}
+                  draftKey={DRAFT_DRAWER_GOAL}
                   pending={create.isPending}
                   onSubmit={(goal, opts) =>
                     create.mutate(
                       { goal: `${prefix}${goal}`, ...opts },
                       {
-                        onSuccess: (run) => showAgentRunInDrawer(run.id),
+                        onSuccess: (run) => {
+                          writeDraft(DRAFT_DRAWER_GOAL, "");
+                          showAgentRunInDrawer(run.id);
+                        },
                         onError: (e) => toast.error(errorMessage(e)),
                       },
                     )