Reasoning Trace Carry-Forward

Problem

Two failure modes pull in opposite directions. If the reasoning trace is dropped between a tool call and its result, the model loses the thread of why it called the tool in the first place, and the next reasoning step starts from a degraded context. If the reasoning trace is instead preserved across user-turn boundaries, conversation history bloats with stale reasoning from earlier tasks and the next user message inherits irrelevant prior thinking that pollutes its own reasoning. Neither 'always carry forward' nor 'always drop' is correct; the team needs a rule keyed to where in the loop the trace appears.

Solution

Define an episode as: from one user turn to the next user turn (inclusive of all intervening tool calls and tool results). Within an episode, preserve assistant reasoning_content as part of the context concatenation across all turns. At the next user turn boundary, drop reasoning_content from prior episodes (the API silently ignores it when passed across boundaries). The user-visible content remains in history; only the reasoning trace is episode-scoped.

When to use

• The model is a reasoning model that emits a separate reasoning trace.
• Within an episode (one user turn through tool calls and results), reasoning context must persist.
• Reasoning traces should be dropped at user-turn boundaries to avoid stale carryover.