Managed Bun toolchain: bunx shim drops argv0 dispatch — `bunx <name>` behaves as `bun <name>`, causing infinite self-recursion with common wrapper scripts

[beorn]

Describe the bug

// package.json
"scripts": { "vitest": "bunx --bun vitest" }

bun vitest run                              # works
bunx -p vite-plus@0.2.4 vp run gate:test    # task = "bun vitest run"
# $ bunx --bun vitest run
# $ bunx --bun vitest run
# … repeats forever (~15/s, 119× in 8s); SIGABRT storm once the fspy shm ring exhausts

Why: vp's task PATH ships bunx as the same shim as bun — exec "$basedir/bun.native" "$@". Real bunx is a symlink to bun; the binary dispatches on argv0 == "bunx" (bins only, never package.json scripts). The shim loses argv0, so in vp tasks bunx <args> ≡ bun <args> → the wrapper script re-invokes itself.

Proof it's the shim (same binary, different invoked name): .../bin/bunx probe runs the package.json SCRIPT; ln -s bun.native bunx && ./bunx probe runs the BIN.

Fix: ship unix bunx as a symlink to bun.native (as bun does), or exec "$basedir/bun.native" x "$@"; bunx.cmd/.ps1 have the same defect. Possibly explains #1627 (CI process explosion since v0.1.21, closed no-repro).

Reproduction URL

https://github.com/beorn/repro-vite-plus-bunx-shim

Steps to reproduce

Clone → bun install → timeout 8 bunx -p vite-plus@0.2.4 vp run gate:test.

System info

vp 0.2.4 (vp env n/a at 0.2.4); managed bun 1.3.14; system bun 1.3.x; node 24; macOS arm64.

Used Package Manager

bun

Validations

Not an upstream bun issue (symlink proof above). No prior report; nearest: #1971 / #1935 / #1948 / #2091, and #1627.

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Disclosure: prepared with help from Claude Fable (Anthropic) as part of our Bun-monorepo → Vite+ effort; verified with live runs and human-reviewed.

[liangmiQwQ]

It is indeed a bun-related bug. It will be fixed soon. Thanks for your reporting.