[Bug] suggestion_handler sends system-only message — fails on MiniMax & Anthropic LLMs

[Ptah-CT]

Summary

handle_get_suggestion_queries in src/memos/api/handlers/suggestion_handler.py builds the LLM request as a single system message:

message_list = [{"role": "system", "content": suggestion_prompt.format(memories=memories)}]
response = llm.generate(message_list)

OpenAI accepts this shape. Several other LLM backends do not, including the ones MemOS already documents/configures (minimax, plus Anthropic-compatible endpoints like the MiniMax Anthropic gateway):

Backend	Endpoint	Response
MiniMax Text API	https://api.minimax.io/v1/chat/completions	HTTP 400 invalid params, chat content is empty (2013)
MiniMax Anthropic-compat	https://api.minimax.io/anthropic/v1/messages	HTTP 400 invalid params, messages must not be empty (2013)
Anthropic native	https://api.anthropic.com/v1/messages	(same — system is a top-level field, messages[] must have ≥1 user turn)

Per MiniMax's own minimal example in the official docs, even system-only is rejected:

{
  "model": "MiniMax-M2.7",
  "messages": [
    { "role": "system", "name": "MiniMax AI" },
    { "role": "user",   "name": "user", "content": "hello" }
  ]
}

Reproduction

1. MOS_CHAT_MODEL=MiniMax-M2.7, OPENAI_API_BASE=https://api.minimax.io/v1, valid OPENAI_API_KEY.
2. POST /product/suggestions with mem_cube_id=<existing cube>, language=en.
3. Server returns HTTP 500. With [Bug] timed_with_status decorator silently swallows exceptions and returns None #1523 fixed: openai.BadRequestError: Error code: 400 ... 'chat content is empty (2013)'. Without: AttributeError: 'NoneType' object has no attribute 'replace'.

Proposed fix

Split the prompt into a short system persona and a user message containing the actual instruction. OpenAI accepts this; MiniMax/Anthropic require it.

message_list = [
    {"role": "system",
     "content": "You generate suggestion queries based on the user's recent memories."},
    {"role": "user",
     "content": suggestion_prompt.format(memories=memories)},
]

This is a strict widening — every backend that accepts the original system-only shape also accepts the split shape. No behaviour change for existing OpenAI/Azure deployments.

PR follows.

Related

• [Bug] timed_with_status decorator silently swallows exceptions and returns None #1523, [Bug] clean_json_response crashes with cryptic AttributeError when given None #1525 — the silent-fail / NoneType crash that this bug currently surfaces as.
• Other handlers in src/memos/api/handlers/ should be audited for the same [{role: system, content: ...}] pattern; I only fixed suggestion_handler in this PR but happy to extend.

[Memtensor-AI]

🤖 AutoDev 已接管此 issue，开始处理。

任务 ID: 17b71cc74829e6eb
工作分支: autodev/MemOS-1527
目标分支: main
流程: opsp（系分 → 编码 → 自测 → PR）

完成后我会在此回贴 PR 链接；若需要补充信息，我会在本 issue 评论中向您反问。

[Memtensor-AI]

🚀 AutoDev task 17b71cc74829e6eb pushed commit.

Summary: 已修复 Issue #1527：suggestion_handler 和 chat_handler 中 3 处 system-only 消息调用现已拆分为 system + user 结构，确保 MiniMax 和 Anthropic API 兼容性。

修改文件：

• src/memos/api/handlers/suggestion_handler.py：修复 _get_further_suggestion() 和 handle_get_suggestion_queries() 两处
• src/memos/api/handlers/chat_handler.py：修复 _get_further_suggestion_queries() 一处
• tests/api/test_suggestion_handler.py：新增测试覆盖消息结构验证

验证结果：

• ✓ Python 语法验证通过
• ✓ Ruff lint 检查通过
• ✓ 消息结构符合 MiniMax/Anthropic API 规范（[system, user] 结构）
• ✓ 向后兼容：OpenAI 行为不变，MiniMax/Anthropic 从拒绝到接受

风险评估：低风险，局部修改，无 API 合约变更，无数据库迁移，向后兼容。

修改已提交到 commit 5bed705 并推送至远端分支 autodev/MemOS-1527，等待 scheduler 创建 PR 并合并到 main。

Base branch: main
Branch: autodev/MemOS-1527
Commit: 5bed705

I will create the PR next and post the PR link here.

[Memtensor-AI]

✅ AutoDev task 17b71cc74829e6eb completed.

Summary: 已修复 Issue #1527：suggestion_handler 和 chat_handler 中 3 处 system-only 消息调用现已拆分为 system + user 结构，确保 MiniMax 和 Anthropic API 兼容性。

修改文件：

• src/memos/api/handlers/suggestion_handler.py：修复 _get_further_suggestion() 和 handle_get_suggestion_queries() 两处
• src/memos/api/handlers/chat_handler.py：修复 _get_further_suggestion_queries() 一处
• tests/api/test_suggestion_handler.py：新增测试覆盖消息结构验证

验证结果：

• ✓ Python 语法验证通过
• ✓ Ruff lint 检查通过
• ✓ 消息结构符合 MiniMax/Anthropic API 规范（[system, user] 结构）
• ✓ 向后兼容：OpenAI 行为不变，MiniMax/Anthropic 从拒绝到接受

风险评估：低风险，局部修改，无 API 合约变更，无数据库迁移，向后兼容。

修改已提交到 commit 5bed705 并推送至远端分支 autodev/MemOS-1527，等待 scheduler 创建 PR 并合并到 main。

Base branch: main
Branch: autodev/MemOS-1527
Commit: 5bed705
PR: #1868
Assigned to: @MatthewZhuang, @CarltonXiang, @syzsunshine219
Reviewers: @MatthewZhuang, @CarltonXiang, @syzsunshine219