diff --git a/app/src/pages/conversations/components/ToolTimelineBlock.tsx b/app/src/pages/conversations/components/ToolTimelineBlock.tsx
index e19b80c90..e4545c925 100644
--- a/app/src/pages/conversations/components/ToolTimelineBlock.tsx
+++ b/app/src/pages/conversations/components/ToolTimelineBlock.tsx
@@ -12,6 +12,7 @@ import {
   stripToolCallEnvelopes,
 } from '../../../utils/toolTimelineFormatting';
 import { parseWorkerThreadRef } from '../utils/workerThreadRef';
+import { BubbleMarkdown } from './AgentMessageBubble';
 import { agentNameTone, AgentTimelineRail } from './AgentTimelineRail';
 import { WorkerThreadRefCard, type WorkerThreadStatus } from './WorkerThreadRefCard';
 
@@ -99,20 +100,30 @@ function ToolCallRow({
 }) {
   const tone = toolCallTone(call.status);
   return (
-    <div className="flex items-center gap-1.5" data-testid="subagent-tool-call">
-      <span className={`text-[11px] ${tone}`}>•</span>
-      <span className="text-[12px] text-content-secondary">
+    <div className="flex min-w-0 items-center gap-1.5" data-testid="subagent-tool-call">
+      <span aria-hidden className={`shrink-0 text-[11px] ${tone}`}>
+        •
+      </span>
+      <span className="shrink-0 text-[12px] whitespace-nowrap text-content-secondary">
         {call.displayName ?? formatToolName(call.toolName)}
       </span>
+      {/* The contextual arg (path / recipient / query) can be long, so it
+          truncates to a single line and absorbs the row's spare width — the
+          full value stays available on hover — instead of wrapping into a
+          multi-line box that knocks the name and status out of alignment. */}
       {call.detail ? (
-        <span className="rounded bg-surface-subtle px-1 font-mono text-[11px] text-content-muted">
+        <span
+          title={call.detail}
+          className="min-w-0 truncate rounded bg-surface-subtle px-1 py-px font-mono text-[11px] text-content-muted">
           {call.detail}
         </span>
       ) : null}
       {/* Status reads as a tinted "Done" / "Failed" / "Running" tag. */}
-      <StatusTag status={call.status} />
+      <span className="shrink-0">
+        <StatusTag status={call.status} />
+      </span>
       {call.elapsedMs != null && call.status !== 'running' ? (
-        <span className="text-[11px] text-content-faint">
+        <span className="shrink-0 text-[11px] text-content-faint">
           {call.elapsedMs >= 1000
             ? `${(call.elapsedMs / 1000).toFixed(1)}s`
             : `${call.elapsedMs}ms`}
@@ -132,14 +143,21 @@ function ToolCallRow({
  */
 function ThoughtBlock({ text }: { text: string }) {
   // Drop any inline `<tool_call>…</tool_call>` envelope the model emitted as
-  // text — the call already shows as its own row — then flatten to one line.
-  const clean = stripToolCallEnvelopes(text).replace(/\s+/g, ' ').trim();
+  // text — the call already shows as its own row. Keep the original newlines
+  // (only trim the ends) so the markdown renderer can see headings, lists,
+  // code fences and emphasis instead of flattening them to one plain line.
+  const clean = stripToolCallEnvelopes(text).trim();
   if (!clean) return null;
+  // Rendered through the shared `BubbleMarkdown` so a thought formats markdown
+  // (bold, code, lists) — but scaled back to the original quiet thought look:
+  // small (12px) and light/muted, not the larger, darker agent-bubble prose.
+  // Descendant overrides on `.prose` beat the typography plugin's base sizing;
+  // code keeps its accent colour so inline `tool_names` still read clearly.
   return (
     <div
       data-testid="subagent-thought"
-      className="my-0.5 border-l-2 border-line pl-2 text-[12px] break-words text-content-muted italic">
-      “{clean}”
+      className="my-0.5 break-words [&_.prose]:text-[12px] [&_.prose]:leading-relaxed [&_.prose]:text-content-muted [&_.prose_strong]:text-content-muted [&_.prose_:is(h1,h2,h3,h4,h5,h6)]:text-[12px] [&_.prose_:is(h1,h2,h3,h4,h5,h6)]:text-content-muted">
+      <BubbleMarkdown content={clean} />
     </div>
   );
 }