group activity entries by plan step + remove inline renderers from chat

- Tool calls in Activity timeline are now tagged with current plan step
- Indented entries show which step they belong to
- Step tracking via update_plan_step(status=running) tool calls
- Removed inline tool renderers from chat (health summary, fleet snapshot, etc.)
  — all tool output now visible only in sidebar Activity timeline

web/src/lib/components/ActivityTimeline.svelte

@@ -59,7 +59,7 @@
             {/if}
             <button
               type="button"
-              class="flex w-full items-start gap-2 px-3 py-1.5 text-left text-xs hover:bg-muted/30 {hasDetail ? 'cursor-pointer' : 'cursor-default'}"
+              class="flex w-full items-start gap-2 {entry.indent ? 'pl-7' : 'px-3'} py-1.5 text-left text-xs hover:bg-muted/30 {hasDetail ? 'cursor-pointer' : 'cursor-default'}"
               onclick={() => hasDetail && toggle(entry.id)}
             >
               <!-- status icon -->

web/src/lib/stores/activity.ts

@@ -13,6 +13,8 @@ export interface ActivityEntry {
   detail?: string
   timestamp: number
   toolName?: string
+  stepSeq?: number
+  indent?: boolean
   status: 'running' | 'done' | 'failed'
 }
 
@@ -39,11 +41,23 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
     })
   }
 
-  // Tool calls (from messages)
+  // Tool calls (from messages). Tag each tool with the plan step that's
+  // currently running when it fires.
+  let currentStepSeq = 0
   let entryIdx = 0
   for (let mi = 0; mi < $msgs.length; mi++) {
     for (const t of $msgs[mi].tools) {
+      // Track current step from update_plan_step calls
+      if (t.type === 'tool_use' && t.name === 'update_plan_step') {
+        const s = (t.args as any)?.seq as number | undefined
+        const status = (t.args as any)?.status as string | undefined
+        if (s && status === 'running') currentStepSeq = s
+      } else if (t.name === 'set_goal' || t.name === 'propose_plan' || t.name === 'complete_task') {
+        currentStepSeq = 0
+      }
+
       const label = toolActivityLabel(t)
+      const stepTag = currentStepSeq > 0 ? currentStepSeq : undefined
       if (t.type === 'tool_use') {
         entries.push({
           id: t.id ?? `tool_${mi}_${entryIdx++}`,
@@ -51,10 +65,11 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
           description: label,
           timestamp: now - ($msgs.length - mi) * 1000,
           toolName: t.name,
+          stepSeq: stepTag,
+          indent: stepTag != null,
           status: 'running'
         })
       } else if (t.type === 'tool_result') {
-        // Find and update matching tool_use entry
         const running = entries.find((e) =>
           e.type === 'tool_running' && e.id === t.id && e.status === 'running'
         )
@@ -76,6 +91,8 @@ export const activityLog = derived([messages, planSteps, currentTask], ([$msgs,
             detail: !t.error ? (typeof t.result === 'string' ? t.result.slice(0, 200) : '') : undefined,
             timestamp: now - ($msgs.length - mi) * 1000,
             toolName: t.name,
+            stepSeq: stepTag,
+            indent: stepTag != null,
             status: t.error ? 'failed' : 'done'
           })
         }