feat(desktop): StreamingIndicator surfaces active tool + target

Replace the random spinner verb with a friendly description of the
tool currently running — "Reading foo.ts", "Editing bar.tsx",
"Running npm", "Searching <pattern>". Falls back to the verb / chatState
label when no tool is active.

Why: users were seeing "Percolating... 51s" with no idea whether the
agent was stuck or genuinely working. The chatStore already tracks
activeToolName + streamingToolInput, the indicator just wasn't using
either.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cc-haha/desktop/src/components/chat/StreamingIndicator.tsx

@@ -8,6 +8,78 @@ function formatElapsed(seconds: number): string {
   return `${m}m ${s}s`
 }
 
+function basename(p: string): string {
+  const parts = p.split(/[/\\]/)
+  return parts[parts.length - 1] || p
+}
+
+function truncate(s: string, n: number): string {
+  return s.length > n ? `${s.slice(0, n - 1)}…` : s
+}
+
+/**
+ * Build a short, user-facing description of the tool that is currently
+ * executing. Tries to parse the partially-streamed JSON input so the
+ * user sees e.g. "Reading foo.ts" instead of "Read".
+ */
+function describeActiveTool(toolName: string, rawInput: string): string {
+  let parsed: Record<string, unknown> | null = null
+  if (rawInput) {
+    try {
+      parsed = JSON.parse(rawInput) as Record<string, unknown>
+    } catch {
+      // Partial JSON during streaming — try regex extraction of common keys.
+      const grab = (key: string): string | null => {
+        const m = rawInput.match(new RegExp(`"${key}"\\s*:\\s*"([^"\\\\]*(?:\\\\.[^"\\\\]*)*)`))
+        return m && m[1] ? m[1] : null
+      }
+      parsed = {
+        file_path: grab('file_path'),
+        command: grab('command'),
+        pattern: grab('pattern'),
+        path: grab('path'),
+        url: grab('url'),
+        description: grab('description'),
+      }
+    }
+  }
+  const filePath = (parsed?.file_path as string | undefined) ?? null
+  const command = (parsed?.command as string | undefined) ?? null
+  const pattern = (parsed?.pattern as string | undefined) ?? null
+  const path = (parsed?.path as string | undefined) ?? null
+  const url = (parsed?.url as string | undefined) ?? null
+  const description = (parsed?.description as string | undefined) ?? null
+
+  switch (toolName) {
+    case 'Read':
+      return filePath ? `Reading ${basename(filePath)}` : 'Reading file'
+    case 'Edit':
+    case 'Write':
+      return filePath ? `Editing ${basename(filePath)}` : 'Editing file'
+    case 'Bash':
+    case 'PowerShell':
+      if (description) return truncate(description, 48)
+      return command ? `Running ${truncate(command.split(/\s+/)[0] || command, 32)}` : 'Running command'
+    case 'Grep':
+      return pattern ? `Searching ${truncate(pattern, 40)}` : 'Searching code'
+    case 'Glob':
+      return pattern ? `Finding ${truncate(pattern, 40)}` : 'Finding files'
+    case 'WebFetch':
+    case 'WebSearch':
+      return url ? `Fetching ${truncate(url, 40)}` : toolName === 'WebSearch' ? 'Searching web' : 'Fetching URL'
+    case 'TodoWrite':
+      return 'Updating plan'
+    case 'Agent':
+      return description ? `Delegating: ${truncate(description, 36)}` : 'Delegating to subagent'
+    case 'Task':
+      return description ? `Subtask: ${truncate(description, 40)}` : 'Running subtask'
+    default:
+      if (filePath) return `${toolName} ${basename(filePath)}`
+      if (path) return `${toolName} ${basename(path)}`
+      return `Running ${toolName}`
+  }
+}
+
 export function StreamingIndicator() {
   const activeTabId = useTabStore((s) => s.activeTabId)
   const sessionState = useChatStore((s) => activeTabId ? s.sessions[activeTabId] : undefined)
@@ -15,17 +87,22 @@ export function StreamingIndicator() {
   const statusVerb = sessionState?.statusVerb ?? ''
   const elapsedSeconds = sessionState?.elapsedSeconds ?? 0
   const tokenUsage = sessionState?.tokenUsage ?? { input_tokens: 0, output_tokens: 0 }
-  let verb: string
-  if (statusVerb) {
-    verb = statusVerb
+  const activeToolName = sessionState?.activeToolName ?? null
+  const streamingToolInput = sessionState?.streamingToolInput ?? ''
+
+  let label: string
+  if (activeToolName) {
+    label = describeActiveTool(activeToolName, streamingToolInput)
+  } else if (statusVerb) {
+    label = statusVerb
   } else {
-    verb = chatState === 'thinking' ? 'Thinking' : chatState === 'tool_executing' ? 'Running' : 'Working'
+    label = chatState === 'thinking' ? 'Thinking' : chatState === 'tool_executing' ? 'Running' : 'Working'
   }
 
   return (
     <div className="mb-2 flex w-fit items-center gap-2 rounded-full border border-[var(--color-border)]/40 bg-[var(--color-surface-container-low)] px-3 py-1">
       <span className="text-[var(--color-brand)] animate-shimmer text-xs">✦</span>
-      <span className="text-xs font-medium text-[var(--color-text-secondary)]">{verb}...</span>
+      <span className="text-xs font-medium text-[var(--color-text-secondary)]">{label}...</span>
       {elapsedSeconds > 0 && (
         <span className="text-[10px] text-[var(--color-text-tertiary)]">
           {formatElapsed(elapsedSeconds)}