dsh-buddy-guard

Fix the CodeBuddy / buddy (Tencent) channel returning HTTP 400 on every request in DeepSeek Harness:

buddy: 请求被拦截，请重新发送 Illegal API invocation from an unapproved channel

中文说明

dsh plugin add github:AsterLuo/dsh-buddy-guard --profile <your-profile>

# pin a version (recommended):
dsh plugin add github:AsterLuo/dsh-buddy-guard#v0.1.0 --profile <your-profile>

Restart DSH afterwards — it is required.

The problem

Pick any model on the buddy channel (hy4-preview, deepseek-v4.1-flash, hy3, …) and every turn fails with HTTP 400 INVALID_REQUEST. The same account and the same endpoint work fine as soon as the request stops carrying the DSH system prompt.

Root cause (measured 2026-10-21)

The upstream does a prefix match on the system content. If the system text starts with

You are an AI agent powered by DeepSeek Harness.

it is rejected outright. None of the following matter — every one was changed and the status stayed 400:

• X-Domain (copilot.tencent.com vs www.codebuddy.cn)
• X-Product-Code / X-Product / X-Agent-Purpose
• X-IDE-Name / X-IDE-Type / X-IDE-Version / User-Agent
• the endpoint (copilot.tencent.com and www.codebuddy.cn behave identically)
• the model (hy4-preview, hy3, deepseek-v4.1-flash are all rejected)

Boundary tests (same account, same endpoint, same user message):

system content	result
You are an AI agent powered by DeepSeek Harness.	400
the same line with one leading space	200
one leading letter / period	200
trailing space / newline / period / a whole paragraph	400
the sentence inside a user message	200
only DeepSeek Harness, or lowercase deepseek harness	200

It matches the start of the system text; prefixing any character breaks the match, and appending anything does not help.

How it works

The plugin listens on system-prompt/assemble and returns a modified assembly whose first non-empty section gets one leading space. renderPrompt joins sections with \n\n, so the whole rendered system text then starts with that space.

Why not llm/stream

The first version hooked llm/stream and called next(modifiedOptions). That did nothing, silently. Cordis implements waterfall as:

const next = () => (cbs.shift() ?? inner)(...args);

next takes no arguments — the modified options were dropped on the floor. The plugin loaded, logged, showed up in --dump-config, and the outgoing request was byte-for-byte unchanged.

Replacing arguments only works through a listener's return value.

Install

dsh plugin add github:AsterLuo/dsh-buddy-guard --profile <your-profile>

This copies the package into your profile's node_modules and registers it in dsh.profile.bundles. Your own cordis.patch.yml is left untouched.

Then restart DSH — the config is read once at startup.

Manual install

1. Copy this repo into <DSH_HOME>/profiles/<profile>/node_modules/dsh-buddy-guard/
2. Append "dsh-buddy-guard" to dsh.profile.bundles in that profile's package.json
3. Add "dsh-buddy-guard": "0.1.0" to dependencies in the same file
4. Verify with --dump-config and look for the buddy-guard row
5. Restart DSH

Configuration

- id: buddy-guard
  name: 'dsh-buddy-guard'
  config:
    enabled: true
    providers:
      - buddy

• enabled — master switch.
• providers — which providers get the prefix. Defaults to ['buddy']; other providers pass through untouched.

Verify it worked

After restarting, switch to a buddy model and send a message. A normal reply means it works. Still getting 400?

1. Re-run --dump-config and confirm the buddy-guard row is there.
2. Confirm lib/index.js exists and is not empty.
3. Confirm the package is listed in dsh.profile.bundles — the most commonly missed step.
4. Confirm you really restarted DSH.

Caveat

This bypasses upstream content moderation. The rule can change at any time. If the same error returns, re-run the boundary tests to find the new trigger before changing GUARD_PREFIX.

The account in question is a CodeBuddy China account (www.codebuddy.cn, the JWT iss points there) while the client sends the international product shape. That mismatch is itself what the upstream means by "unapproved channel" — this plugin only makes it work for now, it does not fix the underlying mismatch. Using workbuddy (international) avoids the check entirely.

Test

npm test

License

MIT