diff --git a/lib/bridge.js b/lib/bridge.js
index 01c2e17..d976c1d 100644
--- a/lib/bridge.js
+++ b/lib/bridge.js
@@ -75,8 +75,10 @@ const defaultSleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
 const REASONING_QUOTE_MAX_CHARS = 800;
 /**
  * Assistant message → markdown for delivery. Reasoning (thinking) blocks are
- * kept, one `> ` quote line each — Telegram renders them as the accent-bar
- * quote style the phone user expects for bash/thinking-style chatter.
+ * kept as EXPANDABLE quotes (`**>`…`||` per Telegram's native markdown spec,
+ * `<blockquote expandable>` in HTML mode) so they stay collapsed on the phone
+ * and visually distinct from tool-call quotes; ordinary quotes in assistant
+ * text remain plain blockquotes.
  */
 function contentToText(content) {
     const parts = [];
@@ -90,7 +92,13 @@ function contentToText(content) {
                 continue;
             if (thinking.length > REASONING_QUOTE_MAX_CHARS)
                 thinking = `${thinking.slice(0, REASONING_QUOTE_MAX_CHARS)}…`;
-            parts.push(thinking.split('\n').map((line) => `> ${line}`).join('\n'));
+            // `||` would open/close spoiler entities in native markdown — neutralize.
+            const lines = thinking.replace(/\|\|/g, '｜｜').split('\n');
+            const last = lines.length - 1;
+            parts.push([
+                '**>💭 思考过程',
+                ...lines.map((line, i) => `> ${line}${i === last ? '||' : ''}`),
+            ].join('\n'));
         }
     }
     return parts.join('\n\n');
diff --git a/lib/format.js b/lib/format.js
index 4ac6ba8..729bbcb 100644
--- a/lib/format.js
+++ b/lib/format.js
@@ -12,22 +12,54 @@ function inlineToHtml(text) {
     html = html.replace(/\*\*([^*\n]+)\*\*/g, '<b>$1</b>');
     return html;
 }
-/** Convert `> …` line groups into `<blockquote>` (Telegram renders it with the accent-colored left bar). */
+/**
+ * Convert `> …` line groups into `<blockquote>` (Telegram renders it with the
+ * accent-colored left bar). The native-markdown expandable-quote form
+ * (`**>first line` … `last line||`) becomes `<blockquote expandable>` — used
+ * for thinking blocks so they stay collapsed and distinct from tool-call
+ * quotes (Telegram has no per-message quote color).
+ */
+const EXPANDABLE_OPEN = '**>';
 function blocksToHtml(text) {
     const lines = text.split('\n');
     const out = [];
     let quote = [];
+    let expandable = false;
     const flush = () => {
         if (quote.length === 0)
             return;
-        out.push(`<blockquote>${inlineToHtml(quote.join('\n'))}</blockquote>`);
+        const open = expandable ? '<blockquote expandable>' : '<blockquote>';
+        out.push(`${open}${inlineToHtml(quote.join('\n'))}</blockquote>`);
         quote = [];
+        expandable = false;
     };
     for (const line of lines) {
-        if (line.startsWith('> '))
-            quote.push(line.slice(2));
-        else if (line === '>')
+        if (line.startsWith(EXPANDABLE_OPEN)) {
+            flush();
+            expandable = true;
+            let content = line.slice(EXPANDABLE_OPEN.length);
+            if (content.endsWith('||')) {
+                quote.push(content.slice(0, -2));
+                flush();
+            }
+            else {
+                quote.push(content);
+            }
+        }
+        else if (line.startsWith('> ')) {
+            let content = line.slice(2);
+            let closed = false;
+            if (expandable && content.endsWith('||')) {
+                content = content.slice(0, -2);
+                closed = true;
+            }
+            quote.push(content);
+            if (closed)
+                flush();
+        }
+        else if (line === '>') {
             quote.push('');
+        }
         else {
             flush();
             out.push(inlineToHtml(line));
diff --git a/src/bridge.ts b/src/bridge.ts
index 1427c5d..4a927e4 100644
--- a/src/bridge.ts
+++ b/src/bridge.ts
@@ -210,8 +210,10 @@ const REASONING_QUOTE_MAX_CHARS = 800
 
 /**
  * Assistant message → markdown for delivery. Reasoning (thinking) blocks are
- * kept, one `> ` quote line each — Telegram renders them as the accent-bar
- * quote style the phone user expects for bash/thinking-style chatter.
+ * kept as EXPANDABLE quotes (`**>`…`||` per Telegram's native markdown spec,
+ * `<blockquote expandable>` in HTML mode) so they stay collapsed on the phone
+ * and visually distinct from tool-call quotes; ordinary quotes in assistant
+ * text remain plain blockquotes.
  */
 function contentToText(content: readonly ContentBlock[]): string {
   const parts: string[] = []
@@ -223,7 +225,13 @@ function contentToText(content: readonly ContentBlock[]): string {
       if (!thinking) continue
       if (thinking.length > REASONING_QUOTE_MAX_CHARS)
         thinking = `${thinking.slice(0, REASONING_QUOTE_MAX_CHARS)}…`
-      parts.push(thinking.split('\n').map((line) => `> ${line}`).join('\n'))
+      // `||` would open/close spoiler entities in native markdown — neutralize.
+      const lines = thinking.replace(/\|\|/g, '｜｜').split('\n')
+      const last = lines.length - 1
+      parts.push([
+        '**>💭 思考过程',
+        ...lines.map((line, i) => `> ${line}${i === last ? '||' : ''}`),
+      ].join('\n'))
     }
   }
   return parts.join('\n\n')
diff --git a/src/format.ts b/src/format.ts
index 0b0fa22..b2b160d 100644
--- a/src/format.ts
+++ b/src/format.ts
@@ -14,20 +14,50 @@ function inlineToHtml(text: string): string {
   return html
 }
 
-/** Convert `> …` line groups into `<blockquote>` (Telegram renders it with the accent-colored left bar). */
+/**
+ * Convert `> …` line groups into `<blockquote>` (Telegram renders it with the
+ * accent-colored left bar). The native-markdown expandable-quote form
+ * (`**>first line` … `last line||`) becomes `<blockquote expandable>` — used
+ * for thinking blocks so they stay collapsed and distinct from tool-call
+ * quotes (Telegram has no per-message quote color).
+ */
+const EXPANDABLE_OPEN = '**>'
+
 function blocksToHtml(text: string): string {
   const lines = text.split('\n')
   const out: string[] = []
   let quote: string[] = []
+  let expandable = false
   const flush = (): void => {
     if (quote.length === 0) return
-    out.push(`<blockquote>${inlineToHtml(quote.join('\n'))}</blockquote>`)
+    const open = expandable ? '<blockquote expandable>' : '<blockquote>'
+    out.push(`${open}${inlineToHtml(quote.join('\n'))}</blockquote>`)
     quote = []
+    expandable = false
   }
   for (const line of lines) {
-    if (line.startsWith('> ')) quote.push(line.slice(2))
-    else if (line === '>') quote.push('')
-    else {
+    if (line.startsWith(EXPANDABLE_OPEN)) {
+      flush()
+      expandable = true
+      let content = line.slice(EXPANDABLE_OPEN.length)
+      if (content.endsWith('||')) {
+        quote.push(content.slice(0, -2))
+        flush()
+      } else {
+        quote.push(content)
+      }
+    } else if (line.startsWith('> ')) {
+      let content = line.slice(2)
+      let closed = false
+      if (expandable && content.endsWith('||')) {
+        content = content.slice(0, -2)
+        closed = true
+      }
+      quote.push(content)
+      if (closed) flush()
+    } else if (line === '>') {
+      quote.push('')
+    } else {
       flush()
       out.push(inlineToHtml(line))
     }