fix(trace-opencode): capture system prompt in LLM span input#8
Merged
Andrew Kent (realark) merged 1 commit intomainfrom Apr 17, 2026
Merged
fix(trace-opencode): capture system prompt in LLM span input#8Andrew Kent (realark) merged 1 commit intomainfrom
Andrew Kent (realark) merged 1 commit intomainfrom
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OpenCode emits the resolved system prompt (AGENTS.md / CLAUDE.md content) via experimental.chat.system.transform — a hook the plugin did not subscribe to. LLM spans therefore rendered with only the user turn, making it impossible to debug prompt behavior in Braintrust. Subscribe to the hook, store the joined system prompt on SessionState, and prepend it as the first message when building LLM span input. The hook's output.system is string[] (not string as sometimes assumed); parts are joined with a blank line so the trace shows one system entry. Mirror the capture in the EventProcessor replay path, the FileLogger, and replay.ts so recorded fixtures reconstruct system prompts too. Tests cover: present, absent (regression guard), multi-part joining, across-turn updates, empty arrays, and the production hook wired end- to-end through createTracingHooks.
Andrew Kent (realark)
approved these changes
Apr 17, 2026
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OpenCode emits the resolved system prompt (AGENTS.md / CLAUDE.md content) via experimental.chat.system.transform — a hook the plugin did not subscribe to. LLM spans therefore rendered with only the user turn, making it impossible to debug prompt behavior in Braintrust.
Subscribe to the hook, store the joined system prompt on SessionState, and prepend it as the first message when building LLM span input. The hook's output.system is string[] (not string as sometimes assumed); parts are joined with a blank line so the trace shows one system entry.
Mirror the capture in the EventProcessor replay path, the FileLogger, and replay.ts so recorded fixtures reconstruct system prompts too.
Tests cover: present, absent (regression guard), multi-part joining, across-turn updates, empty arrays, and the production hook wired end- to-end through createTracingHooks.