# X_SIDE_EFFECTS_MISSING

## Means

a package declares no `sideEffects` at all

## Typical cause

every module is retained in every bundle that imports one binding — measured `2026-08-21` with `buildIslands`: an island importing `@ultimat3/time` weighed 22,214 B, and 5,948 B once `@ultimat3/core` declared the field. A ratchet, because 24 of 30 packages were silent the day the rule landed; the list may shrink and may never grow

## Fix

`bun run side-effects --explain --json`, copy that package's array into its `package.json`, then `bun run scripts/side-effects.ts --unpin <packages/name>`

[CLI and verify](/error-codes#cli-and-verify)