Chat requests fail with REQUEST_EXTENSION when a plugin package is broken

[yowigo]

Environment

• DSH Desktop 2.0.6 (win32, node v24.18.1)
• Windows 11 Pro 10.0.26200
• Profile bundles: @deepseek-ai/dsh-base, @deepseek-ai/dsh-web-app, dshmarket (1.45.1)

Symptom

Every chat turn and every automatic session-title generation fails with:

本轮运行失败
DeepSeek request extension preparation failed  REQUEST_EXTENSION

The API key itself is valid (direct curl against api.deepseek.com returns 200), and the credential service has the key stored.

Root cause

In @deepseek-ai/dsh-llm-deepseek (lib/index.js, the stream() path), any error thrown while preparing request extensions aborts the entire request:

let extensions;
try {
  extensions = await this.config.prepareExtensions({ body, signal, ... });
} catch (error) {
  throw new LlmError("DeepSeek request extension preparation failed", "REQUEST_EXTENSION", { cause: error });
}

The default-enabled extension @deepseek-ai/dsh-plugin-package-inventory-deepseek resolves the package.json of every active loader entry at request time:

ctx.deepseekLlmApiExtensions.register("dsh_plugin_packages", { prepare: async (request) => {
  return { value: { packages: await collectActivePluginPackages(ctx, resolver, hostBaseUrl, request.sessionId) } };
} });

PackageIdentityResolver.resolve() throws (cannot resolve active package ... / manifest missing name or version) when any entry is broken. One broken plugin entry therefore kills every chat request.

How it happened here (repro steps)

1. Install a plugin through the dshmarket UI (e.g. dsh-chat-import); the market hot-mounts it ([dsh-market] hot-mounted dsh-chat-import), which also leaves an empty node_modules/@linxin666/ scope directory behind.
2. Uninstall the plugin. Uninstall cleans up most of it, but leftovers (empty directories, market state records) keep a broken entry resolvable by the loader.
3. Send any message → 100% failure with REQUEST_EXTENSION.
4. Workaround: disable the inventory plugin in the profile patch:

# ~/.dsh/profiles/desktop/cordis.patch.yml
- id: plugin-package-inventory-deepseek
  disabled: true

After this, chat works again (requests simply no longer carry the dsh_plugin_packages field).

Log evidence

2026-09-10 16:57:33.771 [W] [session-title-service] session "session-03a9e481-17fd-4de8-950e-6828967e4fc6": automatic title generation failed: Error: DeepSeek request extension preparation failed
2026-09-10 17:59:41.356 [W] [session-title-service] session "session-9de37f0b-58c8-48ee-8df0-b62f185e7065": automatic title generation failed: Error: DeepSeek request extension preparation failed

(The failure happened ~45 ms after request start — a local resolution error, not a network issue.)

Suggested fixes (either or both)

1. Degrade instead of abort: plugin-package-inventory-deepseek's prepare should catch per-package resolution errors, skip the broken entry (or the whole field), and log a warning — a statistics field must never take down the chat.
2. Surface the cause: the wrapped LlmError hides cause from both the UI and the log file, making this impossible to self-diagnose. Log the cause chain (or include it in the UI error details).

中文摘要

• 现象：发消息/自动标题生成全部报 DeepSeek request extension preparation failed (REQUEST_EXTENSION)，API key 本身有效。
• 根因：llm-deepseek 把扩展准备阶段的任何异常都升级为请求失败；默认启用的 plugin-package-inventory-deepseek 在请求时解析所有活跃插件的 package.json，任一插件条目损坏（如通过 dshmarket 安装又卸载后残留空目录）即抛错。
• 建议：插件清单收集失败应降级为警告并跳过该字段，而不是拒绝整个请求；包装错误应把 cause 输出到日志/UI。