A small fix in Codex 0.151 closes an important accounting gap in multi-agent runs: token usage from spawned descendants, including nested subagents, now rolls into the root goal's budget.
What changed
The release note is short, but the merged implementation is more specific. Descendant usage is applied during both active and idle progress accounting. The accounting baseline resets when the active goal changes, while usage recorded concurrently with a checkpoint is preserved.
The test coverage includes child and grandchild agents, budget exhaustion, unloaded parent runtimes, goal replacement, idle accounting, and concurrent checkpoints.
Why this matters
A budget is useful only if it measures the work it is supposed to stop. In a tree-shaped run, the root agent may delegate most of the expensive work. If those branches are invisible to the root total, the apparent cap is not a reliable stop condition.
Rolling descendant usage upward makes the root budget describe the whole run instead of only the coordinator's visible work. That is especially relevant for long-running agent teams, where nested delegation can otherwise hide how much of the task budget has already been consumed.
What it does not mean
This is task-budget accounting inside Codex. It is not an announcement about ChatGPT subscription quotas, API token prices, or billing. It also does not establish the same behavior in other agent frameworks.
I have not benchmarked this release locally, so I am not claiming a performance or cost improvement. The verified claim is narrower: descendant token usage now contributes to the root goal budget.
The next useful observability question is whether users need only the root total, or also per-agent attribution and branch-level hard caps. Which would help you debug a real multi-agent run?
Sources: Codex 0.151 release and implementation PR #41183.
Disclosure: AI assisted with source triage and copy editing; I checked the claims and boundaries against the linked primary sources.
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