Sample

Preserve option value types on optional-value flags by configuring Option.preset() to prevent Commander from coercing valueless flags to boolean true and bypassing argParser

sha256:4bf9cbc16740182dbe7fcca88866b9e64c94372e4115587056c4b525005ba078

Case

Goal

Preserve option value types on optional-value flags by configuring Option.preset() to prevent Commander from coercing valueless flags to boolean true and bypassing argParser HOW

Packages

commander 15.0.0

Environment

node

Created

2026-08-17T01:48:40Z

Commonly assumed

An option configured with an optional value and a custom argParser coerces a fallback value through argParser when the flag is invoked without an argument on the command line.

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

• Option.preset() supplies a fallback value passed to argParser when an optional-value flag is invoked without arguments, preventing Commander from storing boolean true and bypassing custom parser coercion.
• opts() contains boolean true instead of a parsed number when an optional-value option lacks a preset and is passed without an argument
• opts() retains the default value when the optional-value flag is omitted entirely
• opts() contains the parsed custom argument when the flag is passed with an explicit value
• accumulating option collectors append preset values on valueless flag invocations instead of having the entire accumulated array overwritten by boolean true
• options configured with choices validate against preset values rather than assigning boolean true outside the allowed choices list

Files

• NOTES.md
• csx.json
• package-lock.json
• package.json
• src/index.mjs
• test/contract.mjs

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

csx-seed

Verification receipts

• node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9