feat(ui): show target Space in approval dialog + teach the @mux trigger

- MetaToolApprovalDialog renders a "Space: <name>" chip from the new payload
  field so a user can see (and reject) a write aimed at a Space other than the
  one they expect — important now that a client may pass any space_id.
- Tool Optimization shelf shows an @mux tip so users learn the trigger word for
  driving these tools from their AI client (reads silent, writes approved).
- e2e (meta-tools.wdio): assert the @mux tip renders, and that the approval
  dialog surfaces the target-Space chip; synthetic payloads use the real
  manage_feature_set / bind_current_workspace tool names with space_name.

Signed-off-by: Mohammod Al Amin Ashik <maa.ashik00@gmail.com>

Author: its-mash

apps/desktop/src/features/builtinServers/BuiltinServersPage.tsx

@@ -263,6 +263,20 @@ export function BuiltinServersPage() {
                       </span>
                     )}
                   </div>
+                  <p
+                    className="mb-3 text-xs text-[rgb(var(--muted))]"
+                    data-testid="builtin-mux-trigger-tip"
+                  >
+                    Tip: in your AI client, start a request with{' '}
+                    <code className="rounded bg-[rgb(var(--surface))] px-1 py-0.5 font-mono text-[11px]">
+                      @mux
+                    </code>{' '}
+                    so it knows to drive these tools — e.g.{' '}
+                    <span className="italic">
+                      “@mux build a minimal toolset for this repo”
+                    </span>
+                    . Reads are silent; writes ask for your approval.
+                  </p>
                   <div
                     className={`overflow-hidden rounded-xl border border-[rgb(var(--border))] transition-opacity ${
                       selected.enabled ? '' : 'opacity-50'

apps/desktop/src/features/metaTools/MetaToolApprovalDialog.tsx

@@ -14,6 +14,13 @@ export interface ApprovalRequest {
   payload: {
     tool_name: string;
     summary: string;
+    /**
+     * Name of the Space this write targets. Surfaced as a chip so a change
+     * aimed at a Space other than the one the user expects is obvious — a
+     * client may now pass any `space_id`. Absent for writes with no single
+     * target Space.
+     */
+    space_name?: string | null;
     /**
      * Tool-list diff the dialog renders. Freeform by design — the backend's
      * `ApprovalPayload.diff` is an arbitrary JSON value and each write tool
@@ -112,9 +119,19 @@ export function MetaToolApprovalDialog() {
         <CardContent className="space-y-4">
           <div className="text-sm">
             <p className="font-medium">{current.payload.summary}</p>
-            <p className="text-xs text-[rgb(var(--muted))] mt-1 font-mono">
-              tool:&nbsp;{current.payload.tool_name}
-            </p>
+            <div className="flex flex-wrap items-center gap-2 mt-1">
+              {current.payload.space_name && (
+                <span
+                  className="inline-flex items-center gap-1 rounded-full border border-[rgb(var(--border-subtle))] bg-[rgb(var(--surface))] px-2 py-0.5 text-xs"
+                  data-testid="meta-tool-approval-space"
+                >
+                  Space:&nbsp;<span className="font-medium">{current.payload.space_name}</span>
+                </span>
+              )}
+              <span className="text-xs text-[rgb(var(--muted))] font-mono">
+                tool:&nbsp;{current.payload.tool_name}
+              </span>
+            </div>
           </div>
 
           {current.payload.affects_other_clients && (

tests/e2e/specs/meta-tools.wdio.ts

@@ -29,6 +29,11 @@ describe('Built-in Servers - Tool Optimization UI', () => {
     const card = await byTestId('builtin-server-tool-optimization');
     await expect(card).toBeDisplayed();
 
+    // Selecting the capability surfaces the `@mux` trigger tip so users learn
+    // the language for driving these tools from their AI client.
+    await safeClick(card);
+    await expect(await byTestId('builtin-mux-trigger-tip')).toBeDisplayed();
+
     const space = await getDefaultSpace();
     if (!space) throw new Error('No default space — cannot set up test');
 
@@ -79,8 +84,9 @@ describe('Meta tools - Approval dialog', () => {
       request_id: requestId,
       client_id: '00000000-0000-0000-0000-0000000000aa',
       payload: {
-        tool_name: 'mcpmux_pin_this_session',
-        summary: 'E2E: pin to FeatureSet "tiny" (3 tools)',
+        tool_name: 'mcpmux_manage_feature_set',
+        summary: "Update FeatureSet 'tiny' in Space 'My Space': +0 / -2",
+        space_name: 'My Space',
         diff: {
           before: ['github_create_issue', 'firebase_deploy', 'slack_send'],
           after: ['github_create_issue'],
@@ -96,6 +102,9 @@ describe('Meta tools - Approval dialog', () => {
     const dialog = await byTestId('meta-tool-approval-dialog');
     await dialog.waitForDisplayed({ timeout: TIMEOUT.medium });
 
+    // The target Space is named so cross-Space changes are obvious.
+    await expect(await byTestId('meta-tool-approval-space')).toBeDisplayed();
+
     // Every button is present and clickable.
     await expect(await byTestId('meta-tool-approval-allow-once')).toBeDisplayed();
     await expect(await byTestId('meta-tool-approval-always')).toBeDisplayed();
@@ -110,10 +119,11 @@ describe('Meta tools - Approval dialog', () => {
       request_id: requestId,
       client_id: '00000000-0000-0000-0000-0000000000bb',
       payload: {
-        tool_name: 'mcpmux_set_space_active',
-        summary: 'E2E deny: change space active FS',
+        tool_name: 'mcpmux_bind_current_workspace',
+        summary: "E2E deny: bind workspace in Space 'My Space'",
+        space_name: 'My Space',
         diff: null,
-        raw_args: {},
+        raw_args: { space_id: '22222222-2222-2222-2222-222222222222' },
         affects_other_clients: true,
       },
       expires_at_unix_secs: Math.floor(Date.now() / 1000) + 60,