Function build_tool_trajectory 

pub fn build_tool_trajectory(messages: &[Message]) -> String

Render the conversation as an ordered, structured tool trajectory suitable for feeding to a review LLM. Image blocks are dropped (no text signal) and oversized payloads are head-truncated using the DEFAULT_*_PREVIEW_CHARS caps. The output is human-readable Markdown — the leading numbers make it easy for the LLM to reference specific steps in its rationale.