Agent and Harness Efficiency
Medium impactLive published free itemThree Codex releases in a fortnight all point at context budgets
Subagent budget accounting, three-tier context management, and the end of summary compaction. Read together, the harness is moving from hiding context cost to exposing it.
What changed
Between 30 August and 5 September, Codex shipped subagent budget accounting in 0.151, replaced summary compaction with fresh context windows, and added three-tier context management with an experimental token-budget mode in 0.153. GPT-6 Astra separately added note-preserving context that Codex can search across prior windows.
Why it matters
No single release here is dramatic. Together they are a direction: the harness is being rebuilt so context spend is visible and capped rather than silently compressed. That is a bet that operators want to control context rather than have it managed for them. If it holds, the skill that matters shifts from writing good prompts to setting good budgets, and the operators who learn it first get materially more work from the same plan.
Take
Subagent budget accounting, three-tier context management, and the end of summary compaction. Read together, the harness is moving from hiding context cost to exposing it.
What to do
Turn on whatever budget visibility your harness now offers, even if you do not act on it yet. One week of watching where context actually goes is worth more than any guide, this one included.
Evidence
No public sources are linked yet.