fix(workbench): refine agent dock and smooth map resizing

Unify dock surfaces, headers and dividers, and remove the visible context strip.
Limit pointer resizing to 400-640px and reveal the edge grip on hover.
Resize and redraw the map in the same layout cycle to prevent blanking and lag.
Preserve horizontal centering during conversation control press feedback.

Validation: isolated lint, typecheck, 21 focused unit tests, and 10 relevant
browser checks passed. Snapshot baselines regenerated from the isolated change.
The existing mobile alert summary test also fails on unchanged HEAD because
the expected demo alert source is unavailable in this environment.

src/features/workbench/components/workbench-agent-panels.tsx

@@ -1,6 +1,6 @@
 import { AgentCollapsedRail, AgentCommandPanel, AgentPersona } from "@/features/agent";
-import { useEffect, type ComponentProps } from "react";
-import { getWorkbenchViewportLayout } from "../layout/workbench-layout";
+import { useLayoutEffect, type ComponentProps } from "react";
+import { useAgentPanelResize } from "../hooks/use-agent-panel-resize";
 
 type AgentPanelProps = Omit<ComponentProps<typeof AgentCommandPanel>, "collapsing" | "onCollapse">;
 
@@ -11,6 +11,7 @@ type WorkbenchAgentPanelsProps = {
   personaState: ComponentProps<typeof AgentPersona>["state"];
   statusLabel: string;
   viewportWidth: number;
+  conditionExpanded?: boolean;
   onCollapsePanel: () => void;
   onExpandPanel: () => void;
   onWidthCommit?: (width: number) => void;
@@ -23,28 +24,48 @@ export function WorkbenchAgentPanels({
   personaState,
   statusLabel,
   viewportWidth,
+  conditionExpanded = false,
   onCollapsePanel,
   onExpandPanel,
   onWidthCommit
 }: WorkbenchAgentPanelsProps) {
-  const committedWidth = getWorkbenchViewportLayout(viewportWidth).agentWidth;
+  const { handlePointerDown, panelRef, resizing, width } = useAgentPanelResize(
+    viewportWidth,
+    conditionExpanded
+  );
 
-  useEffect(() => {
-    onWidthCommit?.(committedWidth);
-  }, [committedWidth, onWidthCommit]);
+  useLayoutEffect(() => {
+    onWidthCommit?.(width);
+  }, [width, onWidthCommit]);
 
   return (
     <div
-      className="pointer-events-none absolute bottom-0 left-0 top-14 z-50 hidden lg:block"
-      style={{ width: panelOpen ? committedWidth : 0 }}
+      ref={panelRef}
+      className={`pointer-events-none absolute bottom-0 left-0 top-14 z-50 hidden lg:block${resizing ? " select-none" : ""}`}
+      style={{ width: panelOpen ? width : 0 }}
     >
       {panelOpen ? (
-        <AgentCommandPanel
-          {...panelProps}
-          presentation="desktop-dock"
-          collapsing={panelCollapsing}
-          onCollapse={onCollapsePanel}
-        />
+        <>
+          <AgentCommandPanel
+            {...panelProps}
+            presentation="desktop-dock"
+            collapsing={panelCollapsing}
+            onCollapse={onCollapsePanel}
+          />
+          {!panelCollapsing ? (
+            <div
+              role="separator"
+              aria-label="调整 Agent 面板宽度"
+              aria-orientation="vertical"
+              data-resizing={resizing}
+              onPointerDown={handlePointerDown}
+              className="group pointer-events-auto absolute inset-y-0 -right-1.5 z-10 w-3 cursor-col-resize touch-none"
+            >
+              <span className="pointer-events-none absolute inset-y-0 left-[5px] w-px bg-transparent transition-colors duration-150 group-hover:bg-blue-300/70 group-data-[resizing=true]:bg-blue-400/80 motion-reduce:transition-none" />
+              <span className="agent-resize-grip pointer-events-none absolute left-1/2 top-1/2 h-11 w-[3px] -translate-x-1/2 -translate-y-1/2 rounded-full bg-blue-400 opacity-0 transition-opacity duration-150 group-hover:opacity-100 group-data-[resizing=true]:bg-blue-500 group-data-[resizing=true]:opacity-100 motion-reduce:transition-none" />
+            </div>
+          ) : null}
+        </>
       ) : (
         <div className="absolute left-3 top-5">
           <AgentCollapsedRail

src/features/workbench/components/workbench-top-bar.tsx

@@ -104,7 +104,7 @@ export function WorkbenchTopBar({
   };
 
   return (
-    <header className="acrylic-navigation pointer-events-auto absolute left-0 right-0 top-0 z-30 flex h-14 select-none items-center justify-between gap-2 border-b px-2 sm:gap-3 sm:px-4 md:px-5">
+    <header className="workbench-top-bar acrylic-navigation pointer-events-auto absolute left-0 right-0 top-0 z-30 flex h-14 select-none items-center justify-between gap-2 border-b px-2 sm:gap-3 sm:px-4 md:px-5">
       <div className="flex min-w-0 items-center gap-2 sm:gap-2.5 lg:shrink-0">
         <div
           className={cn(