feat: AI 工具架构重构与微信增强 (0.2.17 → 0.2.22)

0.2.17 收束模型初始工具列表：
- 仅暴露 query_capabilities/query_capability_detail/call_capability 三个入口
- API 能力统一通过 iAs HTTP API 封装，删除重复 YAML 工具

0.2.18 系统提示词拆分：
- 固定系统提示词硬编码，动态附加部分 AI 可维护
- 新增 update_additional_system_prompt 能力和持久化

0.2.19 上下文增强与打断语义：
- /new 拥有最高打断语义，取消运行中任务并清除当前 turn
- raw_message JSONB 原文入库，群聊按 group_id 隔离作用域
- 工具调用说明替代动态附加系统提示词

0.2.20 微信输入中状态：
- 改用官方 getconfig + sendtyping 流程，显式管理 typing 状态

0.2.21 API 文档功能分组：
- /v1/api-docs 返回 groups，帮助 AI 按功能面发现接口

0.2.22 AI API 能力去重：
- 移除与 HTTP endpoint 重复的专用能力，统一用 query_api_docs + call_http_api
- 删除不再编译的 web/memory 工具文件

ias-context/src/routes.rs

@@ -7,7 +7,8 @@ use sqlx::PgPool;
 
 use crate::model::{
     ContextScope, MemoryCreateRequest, MemoryDeleteRequest, MemoryDeleteResponse, MemoryResponse,
-    MemorySearchRequest, MemorySearchResponse, MemoryUpdateRequest,
+    MemorySearchRequest, MemorySearchResponse, MemoryUpdateRequest, ToolCallInstructionGetRequest,
+    ToolCallInstructionResponse, ToolCallInstructionUpdateRequest,
 };
 use crate::repository::ContextRepository;
 
@@ -35,6 +36,10 @@ where
             "/v1/context/memories/{id}",
             patch(update_memory).delete(delete_memory),
         )
+        .route(
+            "/v1/context/tool-instructions",
+            post(get_tool_call_instruction).patch(update_tool_call_instruction),
+        )
         .layer(Extension(ContextRouteState::new(db)))
 }
 
@@ -123,6 +128,44 @@ async fn delete_memory(
     }))
 }
 
+async fn update_tool_call_instruction(
+    headers: HeaderMap,
+    Extension(state): Extension<ContextRouteState>,
+    Json(request): Json<ToolCallInstructionUpdateRequest>,
+) -> Result<Json<ToolCallInstructionResponse>, ApiError> {
+    authorize(&headers)?;
+    let scope = validate_scope(request.identity.scope())?;
+    let content = normalize_prompt_content(request.content)?;
+    let reason = optional_limited_text(request.reason, 500);
+
+    let instruction =
+        ContextRepository::upsert_tool_call_instruction(&state.db, &scope, content, reason, "ai")
+            .await
+            .map_err(api_internal_error)?;
+
+    Ok(Json(ToolCallInstructionResponse {
+        success: true,
+        instruction: Some(instruction),
+    }))
+}
+
+async fn get_tool_call_instruction(
+    headers: HeaderMap,
+    Extension(state): Extension<ContextRouteState>,
+    Json(request): Json<ToolCallInstructionGetRequest>,
+) -> Result<Json<ToolCallInstructionResponse>, ApiError> {
+    authorize(&headers)?;
+    let scope = validate_scope(request.identity.scope())?;
+    let instruction = ContextRepository::get_tool_call_instruction(&state.db, &scope.scope_key)
+        .await
+        .map_err(api_internal_error)?;
+
+    Ok(Json(ToolCallInstructionResponse {
+        success: true,
+        instruction,
+    }))
+}
+
 fn authorize(headers: &HeaderMap) -> Result<(), ApiError> {
     let expected = context_api_key()?;
     let token = headers
@@ -176,6 +219,20 @@ fn required_text(value: &str, field: &str) -> Result<String, ApiError> {
     Ok(value.to_string())
 }
 
+fn normalize_prompt_content(value: String) -> Result<String, ApiError> {
+    let value = value.trim().to_string();
+    if value.chars().count() > 8_000 {
+        return Err(api_bad_request("content 不能超过 8000 个字符"));
+    }
+    Ok(value)
+}
+
+fn optional_limited_text(value: Option<String>, max_chars: usize) -> Option<String> {
+    value
+        .map(|value| value.trim().chars().take(max_chars).collect::<String>())
+        .filter(|value| !value.is_empty())
+}
+
 fn api_bad_request(message: impl Into<String>) -> ApiError {
     (
         StatusCode::BAD_REQUEST,