# Behavior traces — yarnpkg/berry

> Canonical page: https://codevetter.com/unpack/berry/behavior-traces

# Behavior traces — yarnpkg/berry

Scanned commit e4e423a1eb117b5129f20ac626a03eb7a97aedff (2026-09-24). Generated by codevetter codevetter 1.15.0 on 2026-10-02.

Source inspection; upstream code and tests were not executed.

Three concrete flows were followed through their implementation: CLI startup, installation through persistence, and script/binary execution. Startup can terminate by handing control to another Yarn executable. Installation and execution both restore project state, but apply different resolution, linking, and subprocess branches.
- Startup: cli.ts calls getPluginConfiguration(), which reads the standard bundle list and constructs modules/plugins; runExit then calls getBaseCli() and run(). — [packages/yarnpkg-cli/sources/cli.ts#L1-11](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-cli/sources/cli.ts#L1-L11) [packages/yarnpkg-cli/sources/tools/getPluginConfiguration.ts#L6-15](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-cli/sources/tools/getPluginConfiguration.ts#L6-L15) [packages/yarnpkg-cli/sources/lib.ts#L186-201](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-cli/sources/lib.ts#L186-L201)
- Startup dispatch: run() performs validateNodejsVersion → getCoreConfiguration → optional runYarnPath; otherwise checkCwd → initTelemetry → initCommands → cli.process → cli.run. Delegation sets YARN_IGNORE_PATH=1 in the child. — [packages/yarnpkg-cli/sources/lib.ts#L75-86](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-cli/sources/lib.ts#L75-L86) [packages/yarnpkg-cli/sources/lib.ts#L143-170](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-cli/sources/lib.ts#L143-L170)
- Install setup: InstallCommand.execute finds Project, applies applicable lockfile migration settings, finds Cache, requires a workspace, restores state without resolutions, and derives refresh/check behavior from explicit flags or hardened mode before Project.install. — [packages/plugin-essentials/sources/commands/install.ts#L303-342](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/plugin-essentials/sources/commands/install.ts#L303-L342) [packages/plugin-essentials/sources/commands/install.ts#L344-380](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/plugin-essentials/sources/commands/install.ts#L344-L380)
- Install resolution: Project.install runs validateProject, stops on validation errors, snapshots an immutable lockfile, invokes resolveEverything, emits peer warnings, and rejects changed generated lockfile content before fetching. — [packages/yarnpkg-core/sources/Project.ts#L1750-1807](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L1750-L1807) [packages/yarnpkg-core/sources/Project.ts#L1829-1856](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L1829-L1856)
- Install persistence: fetchEverything → optional persist → linkEverything → persistInstallStateFile → post-install validation. UpdateLockfile mode fetches only missing checksums and skips linking; SkipBuild returns from linking before package builds. — [packages/yarnpkg-core/sources/Project.ts#L1116-1120](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L1116-L1120) [packages/yarnpkg-core/sources/Project.ts#L1866-1907](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L1866-L1907) [packages/yarnpkg-core/sources/Project.ts#L1464-1467](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L1464-L1467)
- Run script: RunCommand.execute calls Configuration.find → Project.find → restoreInstallState → hasPackageScript → executePackageScript; initialization creates a temporary binary environment, then wrapScriptExecution wraps portable-shell execution. — [packages/plugin-essentials/sources/commands/run.ts#L69-83](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/plugin-essentials/sources/commands/run.ts#L69-L83) [packages/yarnpkg-core/sources/scriptUtils.ts#L458-476](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/scriptUtils.ts#L458-L476) [packages/yarnpkg-core/sources/scriptUtils.ts#L488-490](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/scriptUtils.ts#L488-L490)
- Run fallback: absent a selected script, RunCommand checks dependency binaries and forwards Node flags; otherwise it accepts one matching colon-named workspace script. Binary execution chooses Node or direct pipevp and removes its binary folder in finally. — [packages/plugin-essentials/sources/commands/run.ts#L88-143](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/plugin-essentials/sources/commands/run.ts#L88-L143) [packages/yarnpkg-core/sources/scriptUtils.ts#L763-787](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/scriptUtils.ts#L763-L787)
- State recovery: restoreInstallState reads and gunzips the saved file, deserializes it, and restores requested categories. When resolution restoration is requested, unreadable state or a changed lockfile triggers applyLightResolution → resolveEverything(lockfileOnly) → persistInstallStateFile. — [packages/yarnpkg-core/sources/Project.ts#L2052-2092](https://github.com/yarnpkg/berry/blob/e4e423a1eb117b5129f20ac626a03eb7a97aedff/packages/yarnpkg-core/sources/Project.ts#L2052-L2092)

Every claim links to its cited files at the pinned commit. Citations identify source evidence; they do not establish runtime correctness. Independent CodeVetter scan — not reviewed by upstream maintainers.

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