fix: 修复 Tool Search 缓存失效 — deferred 工具不再动态注入 tools 数组

移除 deferred 工具的 "discover then include" 逻辑，让 tools 数组在整个会话中
保持稳定（只有 core tools + ToolSearch + ExecuteExtraTool），避免每次发现新
工具时 tools JSON 变化导致 prompt cache 失效。

同时强化工具优先级引导：core tools 优先直接调用，ToolSearch/ExecuteExtraTool
仅作为发现和调用 deferred 工具的最后手段。当模型搜索已加载的 core tool 时，
ToolSearch 返回明确的拒绝提示。

Co-Authored-By: glm-5.1[1m] <zai-org@claude-code-best.win>

src/services/api/claude.ts

@@ -184,7 +184,6 @@ import {
   type ThinkingConfig,
 } from 'src/utils/thinking.js'
 import {
-  extractDiscoveredToolNames,
   isDeferredToolsDeltaEnabled,
   isToolSearchEnabled,
 } from 'src/utils/toolSearch.js'
@@ -1186,28 +1185,24 @@ async function* queryModel(
     useToolSearch = false
   }
 
-  // Filter out ToolSearchTool if tool search is not enabled for this model
-  // ToolSearchTool returns tool_reference blocks which unsupported models can't handle
+  // Dynamic tool loading: filter deferred tools that haven't been discovered yet
   let filteredTools: Tools
 
-  // canDefer is true when the model supports defer_loading.
   // Deferred tools that haven't been discovered are filtered out from the API
   // request — their schemas are only included after ToolSearch discovers them.
-  // With defer_loading, we only include discovered tools to save prompt tokens.
 
   if (useToolSearch) {
-    // Dynamic tool loading: Only include deferred tools that have been discovered
-    // via tool_reference blocks in the message history. This eliminates the need
-    // to predeclare all deferred tools upfront and removes limits on tool quantity.
-    const discoveredToolNames = extractDiscoveredToolNames(messages)
-
+    // Never include deferred tools in the API tools array — they are invoked
+    // via ExecuteExtraTool which looks them up from the global tool registry
+    // at runtime. Keeping the tools array stable preserves the prompt cache
+    // across turns (discovered tools no longer bloat the tools JSON).
     filteredTools = tools.filter(tool => {
-      // Always include non-deferred tools
+      // Always include non-deferred tools (core tools)
       if (!deferredToolNames.has(tool.name)) return true
       // Always include ToolSearchTool (so it can discover more tools)
       if (toolMatchesName(tool, TOOL_SEARCH_TOOL_NAME)) return true
-      // Only include deferred tools that have been discovered
-      return discoveredToolNames.has(tool.name)
+      // All other deferred tools are excluded — use ExecuteExtraTool instead
+      return false
     })
   } else {
     filteredTools = tools.filter(
@@ -1284,11 +1279,8 @@ async function* queryModel(
   )
 
   if (useToolSearch) {
-    const includedDeferredTools = count(filteredTools, t =>
-      deferredToolNames.has(t.name),
-    )
     logForDebugging(
-      `Dynamic tool loading: ${includedDeferredTools}/${deferredToolNames.size} deferred tools included`,
+      `Dynamic tool loading: 0/${deferredToolNames.size} deferred tools in API tools array (all via ExecuteExtraTool)`,
     )
   }
 

src/services/api/openai/index.ts

@@ -53,7 +53,6 @@ import {
 import type { SDKAssistantMessageError } from '../../../entrypoints/agentSdkTypes.js'
 import {
   isToolSearchEnabled,
-  extractDiscoveredToolNames,
   isDeferredToolsDeltaEnabled,
 } from '../../../utils/toolSearch.js'
 import {
@@ -213,17 +212,18 @@ export async function* queryModelOpenAI(
     }
 
     // 5. Filter tools (similar to Anthropic path)
+    // Never include deferred tools in the API tools array — they are invoked
+    // via ExecuteExtraTool which looks them up from the global tool registry
+    // at runtime. Keeping the tools array stable preserves the prompt cache.
     let filteredTools = tools
     if (useToolSearch && deferredToolNames.size > 0) {
-      const discoveredToolNames = extractDiscoveredToolNames(messages)
-
       filteredTools = tools.filter(tool => {
         // Always include non-deferred tools
         if (!deferredToolNames.has(tool.name)) return true
         // Always include ToolSearchTool (so it can discover more tools)
         if (toolMatchesName(tool, TOOL_SEARCH_TOOL_NAME)) return true
-        // Only include deferred tools that have been discovered
-        return discoveredToolNames.has(tool.name)
+        // All other deferred tools are excluded — use ExecuteExtraTool instead
+        return false
       })
     }