Large tool-output handling / mid-loop context management

[fusion94]

PRD: FR-9. Appendix A (context management).

Large tool outputs must be handled gracefully and never silently corrupt the run — the place where token accounting, truncation, and summarization collide.

Scope

• Size-bound and truncate large tool outputs with a marker
• Token accounting within the loop
• Summarize/evict to stay within the context window mid-run

Done when

A tool that emits tens of KB does not blow the context window or break the run.