How does Bifrost measure up against language servers?

Against ten reference language servers on the reviewed legacy core, Bifrost is exact on more cases than the reference server in 7 of 10 comparisons, level in 2, and behind in 1 (rust-analyzer).

Each language server is compared only on the cases it and Bifrost both answer, so a reference server is never charged for an operation it does not offer. These 110 cases are the reviewed legacy core: selected retrospectively from an analyzer-informed corpus, then re-reviewed from source alone. It is the broadest comparison we publish, and deliberately not a preregistered one; the prospective slices carry that stronger claim over fewer languages.

UsageBench is SlopCop's own benchmark: we build it to measure where Bifrost stands against established language servers, and to keep ourselves honest while doing it. Every number here is generated from digest-bound freeze evidence we cannot edit after the fact — our own misses and regressions included.

Evidence slices

182 cases are frozen across 3 slices. Each keeps its own denominator and they are never pooled: the preregistered slices select and review sources before any analyzer runs, while the legacy core was selected retrospectively.

Prospective v1: 36cases; Preregistered · v0.2.0
Prospective v2: 36cases; Preregistered · v0.3.4
Reviewed legacy core: 110cases; Retrospective · v0.3.1

Legacy core, server by server

Strict-contract conformance across 94 shared case comparisons, from release v0.3.1 at revision 8393dafe6b9a. A case counts as exact only with complete token ranges, no unallowed extras, and the one reviewed navigation target. Disagreement is a contract result, not an automatic defect verdict — the evidence map has every hash and denominator.

Ruby LSP

0.26.10

Bifrost9/9Reference2/9

Both exact: 2
Bifrost only: 7
Reference only: 0

Eclipse JDT LS

1.61.0-202607142124

Bifrost10/10Reference4/10

Both exact: 4
Bifrost only: 6
Reference only: 0

TypeScript LS

5.3.0 (TypeScript 5.9.3)

Bifrost16/16Reference12/16

Both exact: 12
Bifrost only: 4
Reference only: 0

clangd

21.0.0

Bifrost10/10Reference7/10

Both exact: 7
Bifrost only: 3
Reference only: 0

Roslyn

vscode-csharp 2.140.9

Bifrost10/10Reference7/10

Both exact: 7
Bifrost only: 3
Reference only: 0

Metals

1.6.8

Bifrost6/7Reference5/7

Both exact: 4
Bifrost only: 2
Reference only: 1

Intelephense

1.18.5

Bifrost7/7Reference6/7

Both exact: 6
Bifrost only: 1
Reference only: 0

Pyright

1.1.411

Bifrost10/10Reference10/10

Both exact: 10
Bifrost only: 0
Reference only: 0

rust-analyzer

2026-07-13

Bifrost8/10Reference10/10

Both exact: 8
Bifrost only: 0
Reference only: 2

gopls

0.23.0

Bifrost5/5Reference5/5

Both exact: 5
Bifrost only: 0
Reference only: 0