docs(llm): document the invalid-credential code

packages/llm/llm/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/llm/llm/README.md
-README.md: ca34ffdeaafdbe061e030c80997b7234ce36a1bd
-README.zh.md: 1f95d3cd641126e129f94fe31269454a1bcce972
+README.md: 618d5f9f7c69c3ff2b420ae3fec96604802bf1be
+README.zh.md: 4b99c477eae694d1315d90920e835fcfde3b571a

packages/llm/llm/README.md

@@ -63,6 +63,10 @@ Streaming is a raw chunk protocol (`block-start`, `text-delta`, `reasoning-delta
 
 Every product adapter sends application identity on provider HTTP requests. `attributionHeaders(identity?)` builds the standard `User-Agent`, defaulting to public `APP_IDENTITY`; white-label deployments may replace but not suppress it. Adapters verify the wire header directly or through their library hook. See [the attribution Agent Note](../../../.agents/notes/implemented/architecture/2026-06-21-mandatory-app-attribution-headers.md).
 
+### API key validation (`api-key.ts`)
+
+Every adapter that puts a credential in an HTTP header judges it the same way before use. `normalizeApiKey(raw)` trims surrounding whitespace, then accepts any non-empty printable-ASCII value (`/^[\x21-\x7E]+$/`, space excluded) or reports why not as an `ApiKeyRejection` (`'empty'` | `'illegalCharacters'`), both carried in the `ApiKeyCheck` result. Absence is never judged: a caller decides whether a value was supplied before asking, since a profile naming no credential authenticates through the provider's own ambient discovery or OAuth.
+
 ### Classes
 
 - `LlmAdapter` — abstract base class for provider adapters. The only required method is `stream()`.
@@ -73,6 +77,7 @@ Every product adapter sends application identity on provider HTTP requests. `att
 - `CONTEXT_WINDOW_EXCEEDED_CODE` — the provider-neutral code both DeepSeek adapters use when a request exceeds the model context window, regardless of thrown-HTTP versus in-band finish delivery. `isContextWindowExceededError(detail)` is their shared conservative classifier for OpenAI-compatible provider detail.
 - `QUOTA_EXCEEDED_CODE` — the non-transient provider-neutral code for exhausted account quota, balance, credits, budget, or usage limits. `isQuotaExceededError(detail)` keeps those failures distinct from request-rate limits.
 - `EMPTY_RESPONSE_CODE` — the provider-neutral code both adapters use for a degenerate provider completion: a terminal `stop` that carried no content blocks at all. Classified as an error finish (not a successful empty message) because the attempt produced nothing durable; `dsh-llm-retry` retries it by default.
+- `INVALID_CREDENTIAL_CODE` — the provider-neutral code for a credential that was supplied but cannot be used: malformed rather than absent, so the fix is to correct the stored value rather than supply one — the distinction from `MISSING_CREDENTIAL`. Deliberately excluded from the default retryable set, since a malformed credential fails identically on every attempt. `assertUsableApiKey(raw, pkg, ref)` throws `LlmError` with this code, the one shared diagnosis every adapter uses for an unusable stored credential.
 
 ### Real adapters
 

packages/llm/llm/README.zh.md

@@ -63,6 +63,10 @@
 
 每个产品适配器都会在提供方 HTTP 请求上发送应用身份。`attributionHeaders(identity?)` 构建标准 `User-Agent`，默认为公开 `APP_IDENTITY`；白标部署可以替换它，但不能抑制它。适配器会直接验证 wire 标头，或通过自身库 hook 验证。详见 [归因 Agent Note](../../../.agents/notes/implemented/architecture/2026-06-21-mandatory-app-attribution-headers.md)。
 
+### API 密钥校验（`api-key.ts`）
+
+每个要把凭据放进 HTTP 标头的适配器，使用前都以同一套规则校验它。`normalizeApiKey(raw)` 先去除首尾空白，再接受任意非空的可打印 ASCII 值（`/^[\x21-\x7E]+$/`，不含空格），否则以 `ApiKeyRejection`（`'empty'` | `'illegalCharacters'`）说明拒绝原因，二者一并包含在 `ApiKeyCheck` 结果中。缺失从不参与校验：调用方会在询问之前自行判断是否提供了值——未点名凭据的 profile 会转由提供方自身的环境发现或 OAuth 完成认证。
+
 ### 类
 
 - `LlmAdapter`：提供方适配器的抽象基类。唯一必需方法是 `stream()`。
@@ -73,6 +77,7 @@
 - `CONTEXT_WINDOW_EXCEEDED_CODE`：当请求超过模型上下文窗口时，无论通过 HTTP 异常抛出还是带内 finish 交付，两个 DeepSeek 适配器都使用的提供方无关 code。`isContextWindowExceededError(detail)` 是它们针对 OpenAI 兼容提供方详细信息的共享保守分类器。
 - `QUOTA_EXCEEDED_CODE`：帐户配额、余额、点数、预算或用量限制耗尽时使用的非短暂提供方无关 code。`isQuotaExceededError(detail)` 使这些失败与请求速率限制保持区分。
 - `EMPTY_RESPONSE_CODE`：两个适配器都使用的提供方无关 code，用于表示退化的提供方生成结果：一个未携带任何内容块的终止 `stop`。它会被分类为错误 finish（而非成功空消息），因为尝试未产生持久内容；`dsh-llm-retry` 默认重试它。
+- `INVALID_CREDENTIAL_CODE`：已提供但无法使用的凭据所用的提供方无关 code——格式错误而非缺失，修复方式是改正已存储的值而非补供一个，这正是它与 `MISSING_CREDENTIAL` 的区别。它被刻意排除在默认可重试集合之外：格式错误的凭据每次尝试都会以同样方式失败。`assertUsableApiKey(raw, pkg, ref)` 会以该 code 抛出 `LlmError`，是每个适配器判定已存储凭据不可用时共用的诊断。
 
 ### 真实适配器