feat(desktop): polish desktop shell and shared WebUI surfaces (#4195)

* feat(desktop): add native host scaffold

* feat(webui): track turns and usage in gateway

* feat(webui): polish desktop chat experience

* feat(apps): add ArcGIS and Joplin logos

* feat(desktop): polish shell and shared surfaces

* fix(webui): avoid preview chips for glob references

* test: align CI expectations for token fallback

* feat(webui): preview prompt rail entries

* feat(webui): add prompt navigator drawer

* style(webui): refine prompt navigator placement

* style(webui): align prompt navigator with header actions

* style(webui): simplify prompt navigator header

* refactor(webui): clean thread resource refresh

* feat(desktop): add native reply notifications

* fix(webui): preserve desktop restart and replay state

* fix(desktop): harden gateway proxy startup

* fix(web): fall back when readability is unavailable

* fix(desktop): hide window instead of closing on macos

* fix(webui): unify desktop header actions

* fix(webui): simplify prompt history rows

* fix(desktop): log notification delivery failures

* chore(desktop): clean source package artifacts

* fix(cron): support one-time relative reminders

* fix(webui): reveal scroll button in place

* Revert "fix(cron): support one-time relative reminders"

This reverts commit 4c4661da120a3c7283e0768412bae48604e7390b.

* refactor(webui): extract token usage heatmap

* docs(desktop): clarify contributor guides

---------

Co-authored-by: chengyongru <2755839590@qq.com>

webui/src/lib/activity-timeline.ts

@@ -38,6 +38,10 @@ export type TurnUnit =
   | { type: "activity"; messages: UIMessage[]; items: ActivityItem[]; turnLatencyMs?: number }
   | { type: "message"; message: UIMessage };
 
+interface NormalizeActivityTimelineOptions {
+  preserveTrailingActivity?: boolean;
+}
+
 export function isReasoningOnlyAssistant(message: UIMessage): boolean {
   if (message.role !== "assistant" || message.kind === "trace") return false;
   if (message.content.trim().length > 0) return false;
@@ -48,24 +52,30 @@ export function isAgentActivityMember(message: UIMessage): boolean {
   return isReasoningOnlyAssistant(message) || message.kind === "trace";
 }
 
-export function normalizeActivityTimeline(messages: UIMessage[]): TurnUnit[] {
+export function normalizeActivityTimeline(
+  messages: UIMessage[],
+  options: NormalizeActivityTimelineOptions = {},
+): TurnUnit[] {
   const units: TurnUnit[] = [];
   let turnMessages: UIMessage[] = [];
+  let activeTurnId: string | undefined;
 
-  const flushTurn = () => {
+  const flushTurn = (flushOptions: NormalizeActivityTimelineOptions = {}) => {
     if (turnMessages.length === 0) return;
 
-    const visibleMessages = visibleMessagesForTurn(turnMessages);
+    const turnUnits: TurnUnit[] = [];
+    const orderedTurnMessages = orderMessagesByTurnSeq(turnMessages);
+    const visibleMessages = visibleMessagesForTurn(orderedTurnMessages);
     let visibleIndex = 0;
     let activityMessages: UIMessage[] = [];
 
     const flushActivityMessages = () => {
       if (!activityMessages.length) return;
-      pushActivityUnits(units, activityMessages, visibleMessages.slice(visibleIndex));
+      pushActivityUnits(turnUnits, activityMessages, visibleMessages.slice(visibleIndex));
       activityMessages = [];
     };
 
-    for (const message of turnMessages) {
+    for (const message of orderedTurnMessages) {
       if (isAgentActivityMember(message)) {
         activityMessages.push(message);
         continue;
@@ -74,34 +84,87 @@ export function normalizeActivityTimeline(messages: UIMessage[]): TurnUnit[] {
       if (assistantHasInlineReasoning(message)) {
         activityMessages.push(reasoningOnlyMessageFromAnswer(message));
         flushActivityMessages();
-        units.push({ type: "message", message: stripInlineReasoning(message) });
+        turnUnits.push({ type: "message", message: stripInlineReasoning(message) });
         visibleIndex += 1;
         continue;
       }
 
       flushActivityMessages();
-      units.push({ type: "message", message });
+      turnUnits.push({ type: "message", message });
       visibleIndex += 1;
     }
 
     flushActivityMessages();
+    units.push(...normalizeCompletedTurnUnits(turnUnits, flushOptions));
     turnMessages = [];
+    activeTurnId = undefined;
   };
 
   for (const message of messages) {
     if (message.role === "user") {
       flushTurn();
       units.push({ type: "message", message });
+      activeTurnId = message.turnId;
       continue;
     }
 
+    if (message.turnId && activeTurnId && message.turnId !== activeTurnId) {
+      flushTurn();
+    }
+    if (message.turnId) {
+      activeTurnId = message.turnId;
+    }
     turnMessages.push(message);
   }
 
-  flushTurn();
+  flushTurn(options);
   return units;
 }
 
+function orderMessagesByTurnSeq(messages: UIMessage[]): UIMessage[] {
+  if (
+    messages.length < 2
+    || !messages.every((message) => Number.isFinite(message.turnSeq))
+  ) {
+    return messages;
+  }
+  return messages
+    .map((message, index) => ({ message, index }))
+    .sort((left, right) => {
+      const bySeq = (left.message.turnSeq ?? 0) - (right.message.turnSeq ?? 0);
+      return bySeq || left.index - right.index;
+    })
+    .map(({ message }) => message);
+}
+
+function normalizeCompletedTurnUnits(
+  turnUnits: TurnUnit[],
+  options: NormalizeActivityTimelineOptions,
+): TurnUnit[] {
+  if (options.preserveTrailingActivity || turnUnits.length < 2) return turnUnits;
+  if (turnUnits[turnUnits.length - 1]?.type !== "activity") return turnUnits;
+
+  let trailingStart = turnUnits.length - 1;
+  while (trailingStart > 0 && turnUnits[trailingStart - 1]?.type === "activity") {
+    trailingStart -= 1;
+  }
+
+  const previous = turnUnits[trailingStart - 1];
+  if (
+    !previous
+    || previous.type !== "message"
+    || previous.message.role !== "assistant"
+  ) {
+    return turnUnits;
+  }
+
+  return [
+    ...turnUnits.slice(0, trailingStart - 1),
+    ...turnUnits.slice(trailingStart),
+    previous,
+  ];
+}
+
 function visibleMessagesForTurn(messages: UIMessage[]): UIMessage[] {
   const visibleMessages: UIMessage[] = [];
   for (const message of messages) {