diff --git a/internal/runtime/executor/claude_executor.go b/internal/runtime/executor/claude_executor.go
index 56c2c5400..7b2e5d8d5 100644
--- a/internal/runtime/executor/claude_executor.go
+++ b/internal/runtime/executor/claude_executor.go
@@ -137,6 +137,7 @@ func (e *ClaudeExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
 
 	// Disable thinking if tool_choice forces tool use (Anthropic API constraint)
 	body = disableThinkingIfToolChoiceForced(body)
+	body = normalizeClaudeTemperatureForThinking(body)
 
 	// Auto-inject cache_control if missing (optimization for ClawdBot/clients without caching support)
 	if countCacheControls(body) == 0 {
@@ -307,6 +308,7 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
 
 	// Disable thinking if tool_choice forces tool use (Anthropic API constraint)
 	body = disableThinkingIfToolChoiceForced(body)
+	body = normalizeClaudeTemperatureForThinking(body)
 
 	// Auto-inject cache_control if missing (optimization for ClawdBot/clients without caching support)
 	if countCacheControls(body) == 0 {
@@ -651,6 +653,25 @@ func disableThinkingIfToolChoiceForced(body []byte) []byte {
 	return body
 }
 
+// normalizeClaudeTemperatureForThinking keeps Anthropic message requests valid when
+// thinking is enabled. Anthropic rejects temperatures other than 1 when
+// thinking.type is enabled/adaptive/auto.
+func normalizeClaudeTemperatureForThinking(body []byte) []byte {
+	if !gjson.GetBytes(body, "temperature").Exists() {
+		return body
+	}
+
+	thinkingType := strings.ToLower(strings.TrimSpace(gjson.GetBytes(body, "thinking.type").String()))
+	switch thinkingType {
+	case "enabled", "adaptive", "auto":
+		if temp := gjson.GetBytes(body, "temperature"); temp.Exists() && temp.Type == gjson.Number && temp.Float() == 1 {
+			return body
+		}
+		body, _ = sjson.SetBytes(body, "temperature", 1)
+	}
+	return body
+}
+
 type compositeReadCloser struct {
 	io.Reader
 	closers []func() error
diff --git a/internal/runtime/executor/claude_executor_test.go b/internal/runtime/executor/claude_executor_test.go
index 89bab2aac..74cec0a35 100644
--- a/internal/runtime/executor/claude_executor_test.go
+++ b/internal/runtime/executor/claude_executor_test.go
@@ -1833,3 +1833,43 @@ func TestApplyCloaking_PreservesConfiguredStrictModeAndSensitiveWordsWhenModeOmi
 		t.Fatalf("expected configured sensitive word obfuscation to apply, got %q", got)
 	}
 }
+
+func TestNormalizeClaudeTemperatureForThinking_AdaptiveCoercesToOne(t *testing.T) {
+	payload := []byte(`{"temperature":0,"thinking":{"type":"adaptive"},"output_config":{"effort":"max"}}`)
+	out := normalizeClaudeTemperatureForThinking(payload)
+
+	if got := gjson.GetBytes(out, "temperature").Float(); got != 1 {
+		t.Fatalf("temperature = %v, want 1", got)
+	}
+}
+
+func TestNormalizeClaudeTemperatureForThinking_EnabledCoercesToOne(t *testing.T) {
+	payload := []byte(`{"temperature":0.2,"thinking":{"type":"enabled","budget_tokens":2048}}`)
+	out := normalizeClaudeTemperatureForThinking(payload)
+
+	if got := gjson.GetBytes(out, "temperature").Float(); got != 1 {
+		t.Fatalf("temperature = %v, want 1", got)
+	}
+}
+
+func TestNormalizeClaudeTemperatureForThinking_NoThinkingLeavesTemperatureAlone(t *testing.T) {
+	payload := []byte(`{"temperature":0,"messages":[{"role":"user","content":"hi"}]}`)
+	out := normalizeClaudeTemperatureForThinking(payload)
+
+	if got := gjson.GetBytes(out, "temperature").Float(); got != 0 {
+		t.Fatalf("temperature = %v, want 0", got)
+	}
+}
+
+func TestNormalizeClaudeTemperatureForThinking_AfterForcedToolChoiceKeepsOriginalTemperature(t *testing.T) {
+	payload := []byte(`{"temperature":0,"thinking":{"type":"adaptive"},"output_config":{"effort":"max"},"tool_choice":{"type":"any"}}`)
+	out := disableThinkingIfToolChoiceForced(payload)
+	out = normalizeClaudeTemperatureForThinking(out)
+
+	if gjson.GetBytes(out, "thinking").Exists() {
+		t.Fatalf("thinking should be removed when tool_choice forces tool use")
+	}
+	if got := gjson.GetBytes(out, "temperature").Float(); got != 0 {
+		t.Fatalf("temperature = %v, want 0", got)
+	}
+}