Document DP033 plugin assembly duplicate key

docs/diagnostics.md

@@ -73,6 +73,20 @@ Help links in the IDE point to this page (`#dp###` anchors).
 
 See also [Registry key conventions](./registry-key-conventions.md).
 
+## Plugin assemblies (DP033) {#dp033}
+
+| ID | Severity | When |
+|----|----------|------|
+| **DP033** | Error | The same **strategy key** for the same contract is registered in **more than one referenced provider assembly** |
+
+**Where it applies:** host (or any) compilations that reference multiple plugin provider assemblies contributing `[RegisterStrategy]` / `[RegisterStrategy<TContract>]` for the same contract with an identical key string.
+
+**Message:** includes the key, contract type, and conflicting assembly names.
+
+**Fix:** use distinct keys per provider assembly, or reference only one provider per contract dimension. Duplicate keys within a **single** assembly remain **DP003** (generator).
+
+See [Plugin assemblies sample](https://github.com/Skymly/DesignPatterns.Samples/tree/main/DesignPatterns.Samples.PluginAssemblies) and the main repo [PluginAssemblies.md](https://github.com/Skymly/DesignPatterns/blob/main/docs/PluginAssemblies.md).
+
 ## State transition table (DP026–DP031) {#state-transition-table-dp026-dp031}
 
 | ID | Severity | When |

docs/zh/diagnostics.md

@@ -72,6 +72,18 @@ IDE 帮助链接指向本页（`#dp###` 锚点）。
 
 另见 [注册表 Key 命名约定](./registry-key-conventions.md)。
 
+## 插件程序集（DP033） {#dp033}
+
+| ID | 级别 | 触发条件 |
+|----|------|----------|
+| **DP033** | Error | 同一契约的相同 **strategy key** 在**多个被引用的供应商程序集**中重复注册 |
+
+**作用范围：** 宿主编译引用多个插件供应商程序集，且对同一契约使用了相同的 `[RegisterStrategy]` key。
+
+**消息：** 包含 key、契约类型与冲突程序集名称。
+
+**修复：** 各供应商使用不同 key，或每个契约维度只引用一个供应商。单程序集内重复 key 仍由 **DP003**（生成器）报告。
+
 ## State 转换表（DP026–DP031） {#state-转换表-dp026-dp031}
 
 | ID | 级别 | 触发条件 |