补全边角

docs/CORE_GUIDE.md

@@ -97,6 +97,7 @@ A property descriptor exposes compile-time structural facts:
 using Property = std::remove_cvref_t<decltype(schema.property<&Device::temperature>())>;
 static_assert(Property::readable);
 static_assert(Property::writable);
+static_assert(Property::runtime_copy_writable);
 using Value = Property::value_type;
 using Accessor = Property::accessor_type;
 ```
@@ -570,7 +571,7 @@ For a synchronized writable property, Structive keeps the corresponding managed
 auto result = erased.runtime_write("temperature", typeid(double), &value);
 ```
 
-Runtime write intentionally performs no implicit conversion. `typeid(double)` must exactly match the property's declared value type, and the pointer must address a live value of that exact type for the duration of the call. A successful runtime write uses the same managed write path and synchronization semantics as typed `write`.
+Runtime write intentionally performs no implicit conversion. `typeid(double)` must exactly match the property's declared value type, and the pointer must address a live value of that exact type for the duration of the call. The boundary copies from a `const` input. If a writable accessor cannot accept that copy input, its descriptor exposes `runtime_copy_writable == false` and runtime access returns `unsupported_runtime_write`; typed `write` still accepts move-only values when the accessor supports them. A successful runtime write uses the same managed synchronization path as typed `write`.
 
 ### 22.3 Result contract
 
@@ -580,6 +581,7 @@ Runtime write intentionally performs no implicit conversion. `typeid(double)` mu
 | `unknown_property` | no schema property has that runtime key |
 | `not_readable` | the property exists but its intrinsic capability is not readable |
 | `not_writable` | the property exists but its intrinsic capability is not writable |
+| `unsupported_runtime_write` | the property is intrinsically writable but its accessor cannot accept the runtime copy-input boundary |
 | `type_mismatch` | runtime write supplied a type different from the declared property value type |
 
 There is no external/persistence access mode and no access-control policy in this API. An adapter decides whether it wants to expose or call runtime read/write; Structive reports only the property's intrinsic capability.

docs/CORE_GUIDE.zh-CN.md

@@ -95,6 +95,7 @@ Descriptor 暴露编译期结构事实：
 using Property = std::remove_cvref_t<decltype(schema.property<&Device::temperature>())>;
 static_assert(Property::readable);
 static_assert(Property::writable);
+static_assert(Property::runtime_copy_writable);
 using Value = Property::value_type;
 using Accessor = Property::accessor_type;
 ```
@@ -562,7 +563,7 @@ auto result = erased.runtime_read("temperature", context, callback);
 auto result = erased.runtime_write("temperature", typeid(double), &value);
 ```
 
-Runtime write 明确不做隐式转换。`typeid(double)` 必须与 Property 声明的 value type 完全一致，`value` 指针在调用期间必须指向这个精确类型的有效对象。成功写入复用 typed `write` 的同一 managed write 和 synchronization 语义。
+Runtime write 明确不做隐式转换。`typeid(double)` 必须与 Property 声明的 value type 完全一致，`value` 指针在调用期间必须指向这个精确类型的有效对象。这个边界从 `const` 输入复制；如果一个 intrinsically writable Accessor 无法接受 copy-input，它会暴露 `runtime_copy_writable == false`，runtime access 返回 `unsupported_runtime_write`，而 typed `write` 在 Accessor 支持时仍可正常接收 move-only 值。成功写入继续复用 typed `write` 的 managed synchronization 路径。
 
 ### 22.3 Result Contract
 
@@ -572,6 +573,7 @@ Runtime write 明确不做隐式转换。`typeid(double)` 必须与 Property 声
 | `unknown_property` | Schema 中不存在该 runtime key |
 | `not_readable` | Property 存在，但 intrinsic capability 不可读 |
 | `not_writable` | Property 存在，但 intrinsic capability 不可写 |
+| `unsupported_runtime_write` | Property intrinsically writable，但 Accessor 无法接收 runtime copy-input 边界 |
 | `type_mismatch` | runtime write 提供的类型和 Property value type 不一致 |
 
 这里没有 external/persistence mode，也没有访问控制 policy。Adapter 自己决定是否对外暴露、是否调用 runtime read/write；Structive 只报告 Property 自身的 intrinsic capability。

docs/DESIGN.md

@@ -298,7 +298,7 @@ Examples:
 - requesting a typed unique guard for a read-only property;
 - reading a write-only property.
 
-Runtime key APIs report dynamic failures through `Runtime_Access_Result`.
+Runtime key APIs report dynamic failures through `Runtime_Access_Result`. The runtime write boundary is copy-input by design: intrinsic `writable` remains a structural fact, while `runtime_copy_writable` states whether the accessor can participate in that type-erased copy boundary. Move-only typed writes therefore do not get mislabeled as structurally non-writable.
 
 ### Rule
 

docs/DESIGN.zh-CN.md

@@ -294,7 +294,7 @@ Adapter 自己决定是否暴露某个 Property、是否调用 runtime read/writ
 - 对 read-only property 请求 typed unique guard；
 - 读取 write-only property。
 
-Runtime key API 才使用 `Runtime_Access_Result` 返回动态错误。
+Runtime key API 才使用 `Runtime_Access_Result` 返回动态错误。Runtime write 明确是 copy-input 边界：intrinsic `writable` 继续表示结构事实，`runtime_copy_writable` 单独表示 Accessor 是否能参与 type-erased copy write。这样 move-only typed write 不会被错误描述成结构上不可写。
 
 ### 原则