fix(ai-adapters): infer anthropic adaptive thinking by claude model capability

src/crates/ai-adapters/src/client.rs

@@ -809,6 +809,119 @@ mod tests {
         assert_eq!(request_body["output_config"]["effort"], "medium");
     }
 
+    #[test]
+    fn build_anthropic_request_body_keeps_manual_thinking_for_pre_adaptive_models() {
+        let client = AIClient::new(AIConfig {
+            name: "anthropic".to_string(),
+            base_url: "https://api.anthropic.com".to_string(),
+            request_url: "https://api.anthropic.com/v1/messages".to_string(),
+            api_key: "test-key".to_string(),
+            model: "claude-sonnet-4-5".to_string(),
+            format: "anthropic".to_string(),
+            context_window: 200000,
+            max_tokens: Some(8192),
+            temperature: None,
+            top_p: None,
+            reasoning_mode: ReasoningMode::Enabled,
+            inline_think_in_text: false,
+            custom_headers: None,
+            custom_headers_mode: None,
+            skip_ssl_verify: false,
+            reasoning_effort: Some("high".to_string()),
+            thinking_budget_tokens: None,
+            custom_request_body: None,
+            custom_request_body_mode: None,
+        });
+
+        let request_body = anthropic::request::build_request_body(
+            &client,
+            &client.config.request_url,
+            None,
+            vec![json!({ "role": "user", "content": [{ "type": "text", "text": "hello" }] })],
+            None,
+            None,
+        );
+
+        assert_eq!(request_body["thinking"]["type"], "enabled");
+        assert_eq!(request_body["thinking"]["budget_tokens"], 6144);
+        assert!(request_body.get("output_config").is_none());
+    }
+
+    #[test]
+    fn build_anthropic_request_body_uses_adaptive_for_opus_4_7_and_newer() {
+        let client = AIClient::new(AIConfig {
+            name: "anthropic".to_string(),
+            base_url: "https://api.anthropic.com".to_string(),
+            request_url: "https://api.anthropic.com/v1/messages".to_string(),
+            api_key: "test-key".to_string(),
+            model: "claude-opus-4-8".to_string(),
+            format: "anthropic".to_string(),
+            context_window: 200000,
+            max_tokens: Some(8192),
+            temperature: None,
+            top_p: None,
+            reasoning_mode: ReasoningMode::Enabled,
+            inline_think_in_text: false,
+            custom_headers: None,
+            custom_headers_mode: None,
+            skip_ssl_verify: false,
+            reasoning_effort: Some("high".to_string()),
+            thinking_budget_tokens: Some(2048),
+            custom_request_body: None,
+            custom_request_body_mode: None,
+        });
+
+        let request_body = anthropic::request::build_request_body(
+            &client,
+            &client.config.request_url,
+            None,
+            vec![json!({ "role": "user", "content": [{ "type": "text", "text": "hello" }] })],
+            None,
+            None,
+        );
+
+        assert_eq!(request_body["thinking"]["type"], "adaptive");
+        assert!(request_body["thinking"].get("budget_tokens").is_none());
+        assert_eq!(request_body["output_config"]["effort"], "high");
+    }
+
+    #[test]
+    fn build_anthropic_request_body_omits_disabled_for_mythos() {
+        let client = AIClient::new(AIConfig {
+            name: "anthropic".to_string(),
+            base_url: "https://api.anthropic.com".to_string(),
+            request_url: "https://api.anthropic.com/v1/messages".to_string(),
+            api_key: "test-key".to_string(),
+            model: "claude-mythos-preview".to_string(),
+            format: "anthropic".to_string(),
+            context_window: 200000,
+            max_tokens: Some(8192),
+            temperature: None,
+            top_p: None,
+            reasoning_mode: ReasoningMode::Disabled,
+            inline_think_in_text: false,
+            custom_headers: None,
+            custom_headers_mode: None,
+            skip_ssl_verify: false,
+            reasoning_effort: None,
+            thinking_budget_tokens: None,
+            custom_request_body: None,
+            custom_request_body_mode: None,
+        });
+
+        let request_body = anthropic::request::build_request_body(
+            &client,
+            &client.config.request_url,
+            None,
+            vec![json!({ "role": "user", "content": [{ "type": "text", "text": "hello" }] })],
+            None,
+            None,
+        );
+
+        assert!(request_body.get("thinking").is_none());
+        assert!(request_body.get("output_config").is_none());
+    }
+
     #[test]
     fn build_anthropic_request_body_adds_deepseek_reasoning_effort() {
         let client = AIClient::new(AIConfig {

src/crates/ai-adapters/src/providers/anthropic/request.rs

@@ -13,6 +13,20 @@ use anyhow::Result;
 use log::{debug, warn};
 use reqwest::RequestBuilder;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum AnthropicThinkingCapability {
+    ManualOnly,
+    AdaptivePreferred,
+    AdaptiveOnly,
+    AdaptiveDefaultNoDisabled,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct ClaudeModelVersion {
+    major: u32,
+    minor: u32,
+}
+
 pub(crate) fn apply_headers(
     client: &AIClient,
     builder: RequestBuilder,
@@ -37,13 +51,40 @@ pub(crate) fn apply_headers(
     })
 }
 
-fn anthropic_supports_adaptive_reasoning(model_name: &str) -> bool {
-    matches!(
-        model_name,
-        name if name.starts_with("claude-opus-4-6")
-            || name.starts_with("claude-sonnet-4-6")
-            || name.starts_with("claude-mythos")
-    )
+fn parse_claude_model_version(model_name: &str, family: &str) -> Option<ClaudeModelVersion> {
+    let prefix = format!("claude-{family}-");
+    let rest = model_name.strip_prefix(&prefix)?;
+    let mut parts = rest.split('-');
+    let major = parts.next()?.parse().ok()?;
+    let minor = parts.next().and_then(|part| part.parse().ok()).unwrap_or(0);
+    Some(ClaudeModelVersion { major, minor })
+}
+
+fn anthropic_thinking_capability(model_name: &str) -> AnthropicThinkingCapability {
+    if model_name.starts_with("claude-mythos") {
+        return AnthropicThinkingCapability::AdaptiveDefaultNoDisabled;
+    }
+
+    if let Some(version) = parse_claude_model_version(model_name, "opus") {
+        if version.major == 4 && version.minor >= 7 {
+            return AnthropicThinkingCapability::AdaptiveOnly;
+        }
+        if version.major > 4 || (version.major == 4 && version.minor >= 6) {
+            return AnthropicThinkingCapability::AdaptivePreferred;
+        }
+    }
+
+    if let Some(version) = parse_claude_model_version(model_name, "sonnet") {
+        if version.major > 4 || (version.major == 4 && version.minor >= 6) {
+            return AnthropicThinkingCapability::AdaptivePreferred;
+        }
+    }
+
+    AnthropicThinkingCapability::ManualOnly
+}
+
+fn anthropic_supports_adaptive_reasoning(capability: AnthropicThinkingCapability) -> bool {
+    !matches!(capability, AnthropicThinkingCapability::ManualOnly)
 }
 
 fn default_anthropic_budget_tokens(max_tokens: Option<u32>) -> Option<u32> {
@@ -77,6 +118,7 @@ fn apply_reasoning_fields(
 ) {
     let is_deepseek_reasoning_target =
         is_deepseek_url(url) || is_deepseek_reasoning_effort_model(model_name);
+    let capability = anthropic_thinking_capability(model_name);
 
     match mode {
         ReasoningMode::Default => {
@@ -90,10 +132,18 @@ fn apply_reasoning_fields(
             }
         }
         ReasoningMode::Disabled => {
-            request_body["thinking"] = serde_json::json!({ "type": "disabled" });
+            if capability == AnthropicThinkingCapability::AdaptiveDefaultNoDisabled {
+                warn!(
+                    target: "ai::anthropic_stream_request",
+                    "Model {} does not support thinking.type=disabled; omitting the field and relying on provider defaults",
+                    model_name
+                );
+            } else {
+                request_body["thinking"] = serde_json::json!({ "type": "disabled" });
+            }
         }
         ReasoningMode::Enabled => {
-            if anthropic_supports_adaptive_reasoning(model_name) {
+            if anthropic_supports_adaptive_reasoning(capability) {
                 apply_anthropic_adaptive_reasoning(request_body, reasoning_effort);
                 return;
             }
@@ -115,7 +165,7 @@ fn apply_reasoning_fields(
             }
         }
         ReasoningMode::Adaptive => {
-            if anthropic_supports_adaptive_reasoning(model_name) {
+            if anthropic_supports_adaptive_reasoning(capability) {
                 apply_anthropic_adaptive_reasoning(request_body, reasoning_effort);
             } else {
                 warn!(
@@ -137,7 +187,7 @@ fn apply_reasoning_fields(
     }
 
     if mode != ReasoningMode::Adaptive
-        && !anthropic_supports_adaptive_reasoning(model_name)
+        && !anthropic_supports_adaptive_reasoning(capability)
         && reasoning_effort.is_some_and(|value| !value.trim().is_empty())
     {
         warn!(

src/web-ui/src/locales/en-US/flow-chat.json

@@ -536,7 +536,7 @@
     "sendingToBtw": "Side session: {{title}}",
     "modeDescriptions": {
       "agentic": "Full-featured AI assistant with access to all tools for comprehensive software development tasks",
-      "Multitask": "Multitask mode: decompose work into orthogonal branches or a DAG and proactively use subagents in parallel when it helps",
+      "Multitask": "Multitask mode: decompose work into orthogonal branches and proactively use subagents in parallel when it helps",
       "Claw": "Personal assistant mode for dedicated assistant workspaces and everyday task support",
       "Plan": "Plan first, execute later — clarify requirements and create an implementation plan before coding",
       "debug": "Evidence-driven systematic debugging: form hypotheses, gather runtime evidence, and fix with confidence",

src/web-ui/src/locales/en-US/scenes/agents.json

@@ -347,7 +347,7 @@
     "GenerateDoc": "Documentation agent: automatically generate code documentation and explanations",
     "Init": "Init agent: help set up project structure and initial configuration",
     "ReviewFixer": "Review fixer agent: automatically fix code issues based on review results",
-    "Multitask": "Multitask mode: decompose work into orthogonal branches or a DAG and use subagents in parallel when beneficial",
+    "Multitask": "Multitask mode: decompose work into orthogonal branches and use subagents in parallel when beneficial",
     "Plan": "Plan mode: create detailed task plans and execution steps",
     "Debug": "Debug mode: systematically diagnose and fix errors in code",
     "Claw": "Claw mode: extract and integrate information from external sources",

src/web-ui/src/locales/zh-CN/flow-chat.json

@@ -530,7 +530,7 @@
     "sendingToBtw": "侧问会话：{{title}}",
     "modeDescriptions": {
       "agentic": "AI 主导执行，自动规划和完成编码任务，拥有完整的工具访问能力",
-      "Multitask": "多任务模式：将工作拆成正交分支或 DAG，并在合适时主动并行调度子 Agent 推进",
+      "Multitask": "多任务模式：将工作拆成正交分支，并在合适时主动并行调度子 Agent 推进",
       "Claw": "个人助理模式：面向个人工作区和日常事务，使用独立的助理上下文",
       "Plan": "先规划后执行，先明确需求并制定实施计划，再进行编码",
       "debug": "证据驱动的系统化调试：提出假设、收集运行时证据、精准定位并修复问题",

src/web-ui/src/locales/zh-CN/scenes/agents.json

@@ -347,7 +347,7 @@
     "GenerateDoc": "文档生成智能体：自动生成代码文档和说明",
     "Init": "初始化智能体：帮助设置项目结构和初始配置",
     "ReviewFixer": "审查修复智能体：根据审查结果自动修复代码问题",
-    "Multitask": "多任务模式：将工作拆为正交分支或 DAG，并在合适时并行使用子智能体推进",
+    "Multitask": "多任务模式：将工作拆为正交分支，并在合适时并行使用子智能体推进",
     "Plan": "规划模式：制定详细的任务计划和执行步骤",
     "Debug": "调试模式：系统性地诊断和修复代码中的错误",
     "Claw": "抓取模式：从外部源提取和整合信息",

src/web-ui/src/locales/zh-TW/flow-chat.json

@@ -530,7 +530,7 @@
     "sendingToBtw": "側問會話：{{title}}",
     "modeDescriptions": {
       "agentic": "AI 主導執行，自動規劃和完成編碼任務，擁有完整的工具訪問能力",
-      "Multitask": "多工模式：將工作拆成正交分支或 DAG，並在合適時主動並行調度子 Agent 推進",
+      "Multitask": "多工模式：將工作拆成正交分支，並在合適時主動並行調度子 Agent 推進",
       "Claw": "個人助理模式：面向個人工作區和日常事務，使用獨立的助理上下文",
       "Plan": "先規劃後執行，先明確需求並制定實施計劃，再進行編碼",
       "debug": "證據驅動的系統化調試：提出假設、收集運行時證據、精準定位並修復問題",

src/web-ui/src/locales/zh-TW/scenes/agents.json

@@ -347,7 +347,7 @@
     "GenerateDoc": "文件生成智慧體：自動生成程式碼文件和說明",
     "Init": "初始化智慧體：幫助設定專案結構和初始配置",
     "ReviewFixer": "審查修復智慧體：根據審查結果自動修復程式碼問題",
-    "Multitask": "多工模式：將工作拆為正交分支或 DAG，並在合適時並行使用子智慧體推進",
+    "Multitask": "多工模式：將工作拆為正交分支，並在合適時並行使用子智慧體推進",
     "Plan": "規劃模式：制定詳細的任務計劃和執行步驟",
     "Debug": "除錯模式：系統性地診斷和修復程式碼中的錯誤",
     "Claw": "抓取模式：從外部來源提取和整合資訊",