refactor(credentials,llm): remove speculative mutation and route lifecycle

docs/core-data-structures/core.zh.md

@@ -25,7 +25,7 @@ harness 是一个微内核：一个极小的核心加上众多插件。大多数
 | [session.md](session.md) | 完整的 `SessionEventMap` 变体目录、`TurnTrigger`/`TurnEndReason`、`deriveMessages()`、执行封闭与独立事件 |
 | [persistence.md](persistence.md) | 持久性 seam：`SessionPersistence`、JSONL + SQLite 后端、`session/flush`、崩溃恢复、`SessionHeader` |
 | [settings.md](settings.md) | 用户设置 seam：`SettingsNamespace` 注册、分层解析（默认值 → 组合 `base` → 用户文档）、owner scope、热提交 |
-| [credentials.md](credentials.md) | 凭据 seam：配置中的 `CredentialRef` 引用（绝不含值）、按操作解析、对 UI 安全的 `CredentialInfo`、provider 来源层 |
+| [credentials.md](credentials.md) | 只读凭据 seam：`CredentialRef` 引用与按操作解析值 |
 | [session-query.md](session-query.md) | 逻辑记录、有界精确事件读取、关系追踪、语义筛选器/文档与全文检索结果页 |
 | [session-title.md](session-title.md) | 持久标题快照、来源 provenance 与异步提供方契约 |
 | [system-prompt.md](system-prompt.md) | 逐次组装的上下文、工具提供方结果、提示词段落与协作式组装 |
@@ -189,33 +189,7 @@ interface MessageSourceMap {
 
 提供方与模型发现使用小型、提供方无关的描述符。模型目录仅供参考：路由仍以已注册提供方为键，适配器也可以接受未列出的模型 id。
 
-注册适配器会返回一个句柄：既是释放器，也带有原子的路由替换——路由集合由用户配置决定的插件正需要它。
-
-```ts type-equiv
-/**
- * What {@link LlmService.registerAdapter} returns: the disposer, plus an
- * atomic route replacement for the same adapter instance.
- */
-interface AdapterRegistrationHandle {
-  /** Release every route this registration currently holds. */
-  (): void
-  /**
-   * Replace this registration's routes with `providers`, keeping the same
-   * adapter instance. The candidate set is validated in full first — a
-   * conflict with another adapter, an invalid name, or bad provider metadata
-   * throws and leaves the current routes untouched — and the swap itself is
-   * one synchronous section, so no request can observe a gap. An empty array
-   * is legal here (a settings section that emptied holds zero routes while
-   * staying registered), unlike an empty initial registration.
-   *
-   * Throws `LlmError` with code `REGISTRATION_DISPOSED` once the registration
-   * has been released: its routes are gone and its disposer has already run,
-   * so anything registered afterwards would have no owner left to release it.
-   * @param providers - the complete next route set for this registration.
-   */
-  replace(providers: string[]): void
-}
-```
+注册适配器会把一组非空提供方路由绑定到调用方 fiber，并返回相应的释放器。路由归组合所有，不属于可变的用户设置。
 
 ```ts type-equiv
 /** Display metadata for one registered provider route. */