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server: canonical harmony system message in gpt-oss fallback

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build_prompt_gpt_oss (the hardcoded builder used when a gpt-oss model
ships no Jinja chat template) emitted the same malformed "You are a
helpful assistant." system message that destabilized the CLI. Replace it
with the canonical harmony system message (identity / knowledge cutoff /
current date via strftime_now / Reasoning: low / channels), matching the
chat_template.jinja build_system_message macro and the xserv-chat fix.

Dormant for gpt-oss-20b (it ships a Jinja template, so the template path
runs), but correct now for any gpt-oss model without one.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Gahow Wang
2026-06-02 15:19:50 +08:00
parent 3d6bb1918e
commit c0a81c84e7
1 changed files with 10 additions and 1 deletions
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11
crates/xserv-server/src/api.rs
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@@ -198,8 +198,17 @@ fn build_prompt_hardcoded(messages: &[Message], model_type: &str) -> String {
fn build_prompt_gpt_oss(messages: &[Message]) -> String {
let mut prompt = String::new();
// Canonical harmony system message (mirrors the model's chat_template.jinja
// build_system_message macro). A hand-rolled substitute puts gpt-oss out of
// distribution and destabilizes channel selection. This hardcoded builder is
// only a fallback for gpt-oss models that ship no Jinja template; the
// gpt-oss-20b release does ship one, so the template path is normally used.
prompt.push_str("<|start|>system<|message|>");
prompt.push_str("You are a helpful assistant.\n\n# Valid channels: analysis, commentary, final. Channel must be included for every message.");
prompt.push_str("You are ChatGPT, a large language model trained by OpenAI.\n");
prompt.push_str("Knowledge cutoff: 2024-06\n");
prompt.push_str(&format!("Current date: {}\n\n", strftime_now("%Y-%m-%d".to_string())));
prompt.push_str("Reasoning: low\n\n");
prompt.push_str("# Valid channels: analysis, commentary, final. Channel must be included for every message.");
prompt.push_str("<|end|>");
let dev_instructions: String = messages
.iter()