phi_evict¶

Offload — lossy, reversible

Ranks tool outputs by a lean-ctx-style context-field score and evicts the lowest until the transcript fits the budget.

How it works¶

phi_evict ranks tool outputs by a lean-ctx-style context-field score and evicts the lowest until the transcript fits budget_tokens. It never evicts the most recent tool output. Evicted outputs are stashed behind a <<cg:HASH>> marker.

\[\Phi = w_R\cdot\text{relevance} + w_H\cdot\text{recency} - w_C\cdot\text{cost} - w_D\cdot\text{redundancy}\]

relevance = keyword overlap with the last user message
recency = position (newest = 1)
cost = share of total tool tokens
redundancy = 1 if a duplicate seen earlier

This is the scalar-ranking essence of lean-ctx's Context Field (the full heat-diffusion/MMR/bandit machinery is a documented refinement).

Before → After¶

before:  [ … many tool outputs, transcript over budget_tokens … ]
after:   [ … lowest-Φ outputs evicted to <<cg:…>> markers until it fits; newest kept … ]

Lossiness¶

Lossy but reversible — evicted outputs are stashed and recovered via context_guru_expand / GET /expand.

Configuration¶

Key	Default	Meaning
`budget_tokens`	120000	Target transcript size; evict until it fits.
`weights`	`balanced`	Φ weight preset (see below).

Weight presets ({R, H, C, D}):

Preset	R (relevance)	H (recency)	C (cost)	D (redundancy)
`balanced`	.40	.20	.30	.10
`aggressive` (punish cost)	.30	.10	.45	.15
`conservative`	.45	.20	.05	.05

When it shines¶

Very long transcripts that must fit a context budget.

When it's inert¶

Total tool tokens ≤ budget, or ≤1 tool output.