diff --git a/internal/llm/client_completions.go b/internal/llm/client_completions.go
index 9dbb42a..8e3e3af 100644
--- a/internal/llm/client_completions.go
+++ b/internal/llm/client_completions.go
@@ -177,18 +177,21 @@ func (c *Client) completions(
 
 // StreamEvent wraps a message or delta produced during streaming.
 type StreamEvent struct {
-	// Type identifies the event kind: delta, done, or message.
+	// Type identifies the event kind: delta, reasoning_delta, done, or message.
 	Type string
 	// Delta is a text fragment from the assistant response.
 	Delta string
+	// ReasoningDelta is a reasoning text fragment from the assistant response.
+	ReasoningDelta string
 	// Message is the complete chat completion message.
 	Message Message
 }
 
 const (
-	streamEventDelta   = "delta"
-	streamEventDone    = "done"
-	streamEventMessage = "message"
+	streamEventDelta          = "delta"
+	streamEventReasoningDelta = "reasoning_delta"
+	streamEventDone           = "done"
+	streamEventMessage        = "message"
 )
 
 // CompletionsStream sends messages to the LLM using the specified model and
@@ -403,6 +406,10 @@ func (c *Client) completionsStream(ctx context.Context, messages []Message, mode
 				acc.reasoning.WriteString(
 					delta.ReasoningContent,
 				)
+				events <- StreamEvent{
+					Type:           streamEventReasoningDelta,
+					ReasoningDelta: delta.ReasoningContent,
+				}
 			}
 			// Accumulate tool call deltas by index.
 			for _, tc := range delta.ToolCalls {
diff --git a/internal/service/service.go b/internal/service/service.go
index ea4fbe8..80086b0 100644
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -585,6 +585,8 @@ type StreamMessage struct {
 	Error string `json:"error,omitempty"`
 	// Delta is a text fragment from the assistant response.
 	Delta string `json:"delta,omitempty"`
+	// ReasoningDelta is a reasoning text fragment from the assistant response.
+	ReasoningDelta string `json:"reasoning_delta,omitempty"`
 	// Message is the chat completion message.
 	Message *llm.Message `json:"message,omitempty"`
 	// Provider is the LLM provider used for the response.
@@ -709,9 +711,10 @@ func (svc *Service) chatStream(w http.ResponseWriter, r *http.Request) {
 	// Consume events and send as SSE.
 	for evt := range events {
 		msg := StreamMessage{
-			Delta:    evt.Delta,
-			Provider: provider,
-			Model:    model,
+			Delta:          evt.Delta,
+			ReasoningDelta: evt.ReasoningDelta,
+			Provider:       provider,
+			Model:          model,
 		}
 		if evt.Message.Role != "" {
 			msg.Message = &evt.Message
diff --git a/internal/service/static/main.js b/internal/service/static/main.js
index a426743..f801a44 100644
--- a/internal/service/static/main.js
+++ b/internal/service/static/main.js
@@ -5,6 +5,7 @@ const PROVIDER_KEY = 'odidere_provider';
 const STORAGE_KEY = 'odidere_history';
 const STREAM_ENDPOINT = '/v1/chat/voice/stream';
 const StreamEventDelta = 'delta';
+const StreamEventReasoningDelta = 'reasoning_delta';
 const StreamEventDone = 'done';
 const StreamEventMessage = 'message';
 const SYSTEM_MESSAGE_KEY = 'odidere_system_message';
@@ -1583,7 +1584,10 @@ class Odidere {
             continue;
           }
 
-          if (eventType === StreamEventDelta) {
+          if (
+            eventType === StreamEventDelta ||
+            eventType === StreamEventReasoningDelta
+          ) {
             if (!streamingMessage) {
               const message = {
                 role: 'assistant',
@@ -1598,8 +1602,21 @@ class Odidere {
               streamingMessage = { message: appended[0], $el };
             }
 
-            streamingMessage.message.content[0].text += event.delta || '';
-            this.#appendStreamingDelta(streamingMessage.$el, event.delta || '');
+            if (eventType === StreamEventDelta) {
+              streamingMessage.message.content[0].text += event.delta || '';
+              this.#appendStreamingDelta(
+                streamingMessage.$el,
+                event.delta || '',
+              );
+            } else {
+              streamingMessage.message.reasoning_content = `${
+                streamingMessage.message.reasoning_content || ''
+              }${event.reasoning_delta || ''}`;
+              this.#appendStreamingReasoningDelta(
+                streamingMessage.$el,
+                event.reasoning_delta || '',
+              );
+            }
             continue;
           }
 
@@ -2263,6 +2280,24 @@ class Odidere {
     this.#scrollToBottom();
   }
 
+  /**
+   * #appendStreamingReasoningDelta appends reasoning text to a streaming
+   * assistant message.
+   * @param {HTMLElement} $msg
+   * @param {string} delta
+   */
+  #appendStreamingReasoningDelta($msg, delta) {
+    let $reasoning = $msg.querySelector('.collapsible--reasoning');
+    if (!$reasoning) {
+      $reasoning = this.#createCollapsibleBlock('reasoning', 'Reasoning', '');
+      const $content = $msg.querySelector('.message__content');
+      $msg.querySelector('.message__body').insertBefore($reasoning, $content);
+    }
+
+    $reasoning.querySelector('pre').textContent += delta;
+    this.#scrollToBottom();
+  }
+
   /**
    * #finalizeStreamingAssistantMessage replaces a streaming placeholder with
    * a fully bound assistant message.