Grasp · Comprehension Index Scan Report

Who still understands tokio-rs/tokio?

Computed from git metadata only; no source code contents were read.
touch-weighted · 3-year history window · last commit 18d ago · scores are comparable only against same-mode scans

Grasp Score

touch-weighted living knowledge across the repo

Active humans

59 / 388

contributors active in last 90 days vs. all-time

AI-attributed minimum

≥ 0.2%

hard evidence only. Just 4% of commits here carry any attribution signal, so the real share is higher

Inactive share

49.4%

work by authors with no commit in the window; silence, not proof of departure

Composition

64/26/8/2%

source / tests / docs / config share of scored work

Living, source only

56%

the headline recomputed over hand-written source alone

Score stability

moderate

90-day-cliff variant reads 47%–67% across 60/90/180-day activity windows; read the width before the middle value

Squash-merged history: 99% of the commits analysed here collapsed a whole pull request into one commit by one author. Squashing credits a single person for everyone's work and can strip the co-author trailers that name the rest (measured across heavy squashers, roughly a quarter to a third of squash commits still carry them, and those are credited), so for this repository the concentration figures are an upper bound, the bus factors are a lower bound, and the AI-attribution minimum is lower than it would be with the same work merged conventionally. That information is destroyed at merge time and cannot be recovered from the repository, so it is reported rather than corrected. Comparisons against a project that does not squash are comparisons across two different record-keeping systems.

Dark-code ranking

Modules ranked by comprehension risk: the unknown share, amplified by ongoing change and thin ownership. The green meter is living knowledge.

Module	Risk	Living knowledge	AI-attr.	Inactive	Bus	Heat/180d
tokio/src/sync	LOW 48	48%	0%	60%	1	34
tokio/src/net	LOW 46	50%	1%	58%	1	32
tokio/tests	LOW 43	57%	0%	51%	1	130
tokio-util	LOW 43	55%	0%	54%	1	44
tokio/src/runtime	LOW 42	58%	0%	49%	1	172
tokio/src/task	LOW 41	49%	0%	58%	1	9
tokio/src/process	LOW 41	46%	0%	63%	1	1
tokio/src/io	LOW 40	56%	1%	50%	1	30
tokio/src/time	LOW 40	49%	0%	59%	1	7
tokio-stream	LOW 39	61%	0%	47%	1	51
benches	LOW 37	53%	0%	55%	1	6
tokio-macros	LOW 35	58%	0%	43%	1	18
tokio/src/macros	LOW 35	57%	0%	57%	1	10
.github	LOW 33	64%	0%	41%	1	35
examples	LOW 33	58%	0%	52%	1	8
(root)	LOW 32	64%	0%	39%	1	31
tokio/src	LOW 32	54%	0%	47%	2	4
tokio/src/util	LOW 30	63%	0%	42%	1	10
tokio	LOW 30	70%	0%	28%	1	54
tokio/src/fs	LOW 28	67%	0%	39%	1	22

One commit touched 81% of every file changed in this window. Wide, shallow commits, a formatter run or a license-header pass, add weight for their author across the whole surface while changing little. Worth looking at what that commit was before crediting the score to its author.

Public-repo caveat: "departed" includes drive-by contributors, overstating attrition relative to a company repo with a real roster. Engagement is a proxy for comprehension. Treat it as a potential indicator rather than a diagnosis.