* feat(chat): template.system_messages_after_first — merge or forward late system turns
Tokenizer chat templates such as Qwen3.8 / Qwen3.8-Flash-Next raise
'System message must be at the beginning' for system-role messages that
appear after the leading system block, while agent frameworks (cogito tool
selection and adjustment prompts) legitimately append system instructions
mid-conversation. Every such request failed with a 500 (48 errors in one
10-task agent run).
New per-model option template.system_messages_after_first:
merge fold late system turns into the leading system message
user forward them as user-role turns at their original position
Default (unset) keeps the current pass-through behaviour.
Fixes#11876
Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Stefan Walcz <stefan.walcz@walcz.de>
* docs(model-config): document template.system_messages_after_first
Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Stefan Walcz <stefan.walcz@walcz.de>
* fix(config/meta): register template.system_messages_after_first in the field registry
TestAllFieldsHaveRegistryEntries requires every model-config field to have
a registry entry. Adds the entry (templates section, select component) and
the option list for the new field so the coverage gate passes.
Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Stefan Walcz <stefan.walcz@walcz.de>
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Signed-off-by: Stefan Walcz <stefan.walcz@walcz.de>
Stefan Walcz
109244a76a