effect-uai auto-compaction

History is just state. Compaction is just a state transition. When the running history crosses a turn or token budget, summarize all but the last few items via the model and replace them with the summary, then keep going.

Reach for this when the user says any of:

• "My agent runs out of context window after long conversations"
• "Summarize chat history when it gets too long"
• "Token budget management for chat agents"

State