fix(subagent): append output-language.md to subagent system prompt and prioritize project-level settings

[zhangxy-zju]

TLDR

SubAgent's system prompt was missing global user memory context (QWEN.md and output-language.md), causing it to ignore project conventions and language preferences. Additionally, output-language.md only supported user-level (~/.qwen/) configuration with no project-level override.

This PR fixes both issues:

• SubAgent now appends getUserMemory() (which includes QWEN.md and output-language.md) to its system prompt, consistent with the main Agent.
• The CLI config loader now checks for .qwen/output-language.md in the project directory first, falling back to the global ~/.qwen/output-language.md.

Dive Deeper

Problem 1: SubAgent ignores output-language.md and QWEN.md

In packages/core/src/subagents/subagent.ts, the buildChatSystemPrompt method only assembled the subagent's own prompt and hardcoded non-interactive rules. It never called this.runtimeContext.getUserMemory(), which is the combined content of QWEN.md files and output-language.md. The main Agent does this via getCoreSystemPrompt(userMemory, model) in client.ts.

Fix: Append this.runtimeContext.getUserMemory() at the end of the subagent's system prompt using the same \n\n---\n\n separator pattern as the main Agent.

Problem 2: No project-level output-language.md support

In packages/cli/src/config/config.ts, loadCliConfig hardcoded the path to Storage.getGlobalQwenDir() + 'output-language.md' (i.e., ~/.qwen/output-language.md). There was no mechanism to allow per-project language overrides.

Fix: Check for .qwen/output-language.md in the current working directory first. If it exists, use it; otherwise fall back to the global path.

Reviewer Test Plan

1. SubAgent language inheritance:

   • Set ~/.qwen/output-language.md to Chinese (or any non-English language).
   • Run a task that spawns a SubAgent (e.g., use the Task tool).
   • Verify the SubAgent responds in the configured language.

2. Project-level override:

   • Create .qwen/output-language.md in a project directory with a different language than the global one.
   • Run qwen from that project directory and trigger a SubAgent task.
   • Verify the project-level language takes precedence.

3. Backward compatibility:

   • Remove any project-level .qwen/output-language.md.
   • Verify the global ~/.qwen/output-language.md is still loaded correctly for both main Agent and SubAgent.

Testing Matrix

	🍏	🪟	🐧
npm run	✅	❓	❓
npx	❓	❓	❓
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-

Linked issues / bugs

Fixes #1986

[zhangxy-zju]

自测效果：subagent的system prompt后增加了output-language.md

[zhangxy-zju]

output-language.md 中用的措辞是 "Prefer"（偏好），这是一个较弱的指令。
LLM的输出语言可控性较差（可能会跟随用户的输入语言；跟随注入的QWEN.md, SKILL中的语言等），导致整个会话中英文混杂


通过把偏好改成强制。 在用户明确指定语言的情况下除外，有比较好的效果，整个会话风格能够保持一致

[pomelo-nwu]

@zhangxy-zju Thanks for your contribution！

[yiliang114]

hi @zhangxy-zju 👋 Thanks for the contribution! 🎉

Code looks great — clean, consistent, and solves the problem perfectly. LGTM! 🚀

My only suggestion would be to add some unit tests in a follow-up PR when you have time. No worries for this one though — the implementation is solid and the manual test plan covers the
important scenarios.

Thanks again, and welcome to Qwen Code! ❤

[zhangxy-zju]

hi @zhangxy-zju 👋 Thanks for the contribution! 🎉

Code looks great — clean, consistent, and solves the problem perfectly. LGTM! 🚀

My only suggestion would be to add some unit tests in a follow-up PR when you have time. No worries for this one though — the implementation is solid and the manual test plan covers the important scenarios.

Thanks again, and welcome to Qwen Code! ❤

Thanks for the warm welcome and the review! 🙏

I've just pushed a follow-up commit (0788003) that adds unit tests covering the changes:

• 3 tests for SubAgentScope.buildChatSystemPrompt: verifies userMemory is correctly appended, and that empty/whitespace-only memory doesn't inject separators
• 3 tests for output-language.md path resolution: verifies project-level priority, global fallback, and the case when neither exists

Note: the existing config.test.ts and config.integration.test.ts in packages/cli have a pre-existing https module resolution failure in the test environment, so the path resolution tests were placed in languageUtils.test.ts where they can run cleanly.

I also have a separate PR #2005 coming for strengthening the output-language template wording (from "Prefer" to "MUST always respond") — splitting it out to keep this PR focused.

[tanzhenxin]

LGTM!