# docs(session): record subagent "latest snapshot wins" tradeoff

`ee55b68`→[main](/content/gh/entireio/cli/commits/main/index.html)·

suhaanthayyil·4d ago·1 file·+16 added/-1 removed

Document that TokenUsage.SubagentTokens is replaced (not summed): a mid-session main-transcript reset or rotation can make a later cumulative snapshot smaller than an earlier one, so the session-wide subagent total regresses (undercounts) for the rest of the session. This is accepted over the prior multiplicative overcount, and checkpoint deltas are unaffected because CheckpointTokenUsage.SubagentTokens is (cumulative - baseline) floored at zero by clampSubtract.

## Changes

1

- cmd/entire/cli/session

- Mstate.go+16/-1

```
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// Set from hook data when the agent provides it.
	ModelName string `json:"model_name,omitempty"`

// Token usage tracking (accumulated across all checkpoints in this session)
	// Token usage tracking (accumulated across all checkpoints in this session).
	//
	// DECISION: SubagentTokens is "latest snapshot wins", not summed. Subagent
	// usage arrives as a cumulative-since-session-start total (each subagent
	// transcript is re-read from line 0 every call), so accumulateTokenUsage
	// replaces rather than adds it (see cmd/entire/cli/strategy). Tradeoff: if
	// the main transcript resets or rotates mid-session (compaction writing a
	// fresh file, or a resume that truncates), a subsequent snapshot can be
	// SMALLER than a previous one, so this session-wide total regresses
	// (undercounts) for the rest of the session. This is accepted: undercounting
	// after a transcript reset is preferable to the multiplicative overcount the
	// summing approach produced, and the alternative (a session-wide high-water
	// mark) would mask genuine subagent-transcript cleanup. Checkpoint deltas do
	// not share this exposure — CheckpointTokenUsage.SubagentTokens is derived as
	// (this total - SubagentTokensBaseline) and floored at 0 by clampSubtract, so
	// a shrunk snapshot yields 0, never a negative or stale delta.
	TokenUsage *agent.TokenUsage `json:"token_usage,omitempty"`

// CheckpointTokenUsage tracks hook-provided token usage since the last condensation.
```

Mcmd/entire/cli/session/state.go+16/-1