diff --git a/navi/core/agent.py b/navi/core/agent.py
index cafadfc..0275924 100644
--- a/navi/core/agent.py
+++ b/navi/core/agent.py
@@ -600,7 +600,7 @@
         """
         tool_map = {t.name: t for t in tools}
         for tc in turn_tool_calls:
-            yield ToolStarted(tool_name=tc.name, arguments=tc.arguments)
+            yield ToolStarted(tool_name=tc.name, arguments=tc.arguments, tool_call_id=tc.id)
 
             sink: asyncio.Queue = asyncio.Queue()
             sink_token = current_event_sink.set(sink)
@@ -647,6 +647,7 @@
                     yield ToolEvent(
                         tool_name=tc.name, arguments=tc.arguments,
                         result="Tool execution was stopped by the user.", success=False,
+                        tool_call_id=tc.id,
                     )
                     session.messages.append(Message(
                         role="tool", content="Tool execution was stopped by the user.",
@@ -664,6 +665,7 @@
                     tool_event = ToolEvent(
                         tool_name=tc.name, arguments=tc.arguments,
                         result=f"Error: {r}", success=False,
+                        tool_call_id=tc.id,
                     )
                     msg = Message(role="tool", content=f"Error: {r}", tool_call_id=tc.id, name=tc.name, metadata={})
                     image_msg = None
diff --git a/navi/core/events.py b/navi/core/events.py
index 6449d7f..33f5ffc 100644
--- a/navi/core/events.py
+++ b/navi/core/events.py
@@ -10,6 +10,7 @@
     tool_name: str
     arguments: dict
     is_subagent: bool = False   # True when emitted from inside run_ephemeral
+    tool_call_id: str = ""      # Stable id for client-side tool_started → tool_call pairing
 
     def to_wire(self) -> dict:
         return {
@@ -17,6 +18,7 @@
             "tool": self.tool_name,
             "args": self.arguments,
             "is_subagent": self.is_subagent,
+            "tool_call_id": self.tool_call_id,
         }
 
 
@@ -30,6 +32,7 @@
     success: bool
     is_subagent: bool = False   # True when emitted from inside run_ephemeral
     metadata: dict = field(default_factory=dict)  # Extra data for client rendering
+    tool_call_id: str = ""      # Stable id for client-side tool_started → tool_call pairing
 
     def to_wire(self) -> dict:
         return {
@@ -40,6 +43,7 @@
             "success": self.success,
             "is_subagent": self.is_subagent,
             "metadata": self.metadata,
+            "tool_call_id": self.tool_call_id,
         }
 
 
diff --git a/navi/core/subagent_runner.py b/navi/core/subagent_runner.py
index 72f8210..1c6c202 100644
--- a/navi/core/subagent_runner.py
+++ b/navi/core/subagent_runner.py
@@ -350,6 +350,7 @@
                                 tool_name=tc.name,
                                 arguments=tc.arguments,
                                 is_subagent=True,
+                                tool_call_id=tc.id,
                             )
                         )
 
@@ -398,6 +399,7 @@
                                 result=content,
                                 success=success,
                                 is_subagent=True,
+                                tool_call_id=tc.id,
                             )
                         )
 
diff --git a/navi/core/tool_executor.py b/navi/core/tool_executor.py
index 4cc77c9..7c049b5 100644
--- a/navi/core/tool_executor.py
+++ b/navi/core/tool_executor.py
@@ -97,7 +97,8 @@
         if tool is None:
             content = f"Error: tool '{tc.name}' not found."
             event = ToolEvent(tool_name=tc.name, arguments=tc.arguments,
-                              result=content, success=False)
+                              result=content, success=False,
+                              tool_call_id=tc.id)
         else:
             log.info("tool.execute", tool=resolved_name, requested_tool=tc.name, args=tc.arguments)
             middlewares = getattr(self._tools, "_middlewares", [])
@@ -110,7 +111,8 @@
             metadata = result.metadata or {}
             event = ToolEvent(tool_name=resolved_name, arguments=tc.arguments,
                               result=content, success=result.success,
-                              metadata=metadata)
+                              metadata=metadata,
+                              tool_call_id=tc.id)
             if result.success and result.metadata and result.metadata.get("is_image"):
                 b64 = result.metadata.get("base64")
                 if b64:
diff --git a/tests/unit/core/test_events.py b/tests/unit/core/test_events.py
index b3b1222..e023397 100644
--- a/tests/unit/core/test_events.py
+++ b/tests/unit/core/test_events.py
@@ -30,6 +30,7 @@
             "tool": "fs",
             "args": {"action": "read"},
             "is_subagent": False,
+            "tool_call_id": "",
         }
 
     def test_to_wire_subagent(self):
@@ -54,6 +55,7 @@
             "success": True,
             "is_subagent": False,
             "metadata": {"size": 42},
+            "tool_call_id": "",
         }
 
 
diff --git a/webclient/src/stores/chat.js b/webclient/src/stores/chat.js
index 5f787a7..524226f 100644
--- a/webclient/src/stores/chat.js
+++ b/webclient/src/stores/chat.js
@@ -312,6 +312,7 @@
     const card = {
       kind: 'tool',
       id: `tool_${Date.now()}`,
+      toolCallId: data.tool_call_id ?? null,
       name: data.tool,
       args: data.args,
       result: null,
@@ -338,7 +339,10 @@
         let step = null
         for (let i = spawn.steps.length - 1; i >= 0; i--) {
           const t = spawn.steps[i]
-          if (t.kind === 'tool' && t.name === data.tool && t.pending) { step = t; break }
+          const match = data.tool_call_id
+            ? t.toolCallId === data.tool_call_id
+            : t.kind === 'tool' && t.name === data.tool && t.pending
+          if (match) { step = t; break }
         }
         if (step) {
           step.result = data.result
@@ -352,7 +356,10 @@
     let card = null
     for (let i = msg.tools.length - 1; i >= 0; i--) {
       const t = msg.tools[i]
-      if (t.kind === 'tool' && t.name === data.tool && t.pending) { card = t; break }
+      const match = data.tool_call_id
+        ? t.toolCallId === data.tool_call_id
+        : t.kind === 'tool' && t.name === data.tool && t.pending
+      if (match) { card = t; break }
     }
     if (card) {
       card.result = data.result