When minChars is set low, compressed markers could be re-compressed
with incorrect char counts. Skip blocks whose content already starts
with the compression prefix.
Replace consumed tool results with compact markers before each LLM call,
freeing context budget in multi-turn agent runs. A tool result is
"consumed" once the assistant has produced a response after seeing it.
- Add `compressToolResults` option to AgentConfig / RunnerOptions
- Runs before contextStrategy (lightweight, no LLM calls)
- Error results and short results (< minChars, default 500) are skipped
- 9 test cases covering default off, compression, parallel tools,
4+ turn compounding, error exemption, custom threshold, and
contextStrategy coexistence