brew-cask: completion target

Error message

brew-cask: completion target '{}' already points to '{}' and is not owned by cask '{}'

What it means

For an existing symlink at a cask completion target, mise resolves it and checks ownership: the link must point at the staged caskroom artifact (or, for appdir artifacts, a file identical to the matching staged app source). If the resolved link points elsewhere, the target is owned by another installation (or a stale link), so mise bails instead of repointing a link it doesn't own.

Solutions

Remove the foreign/stale symlink at the target path and retry the cask install.
Identify what created the link (brew cask, other tool) and uninstall that owner first.
If the link points at a deleted old version, it is stale — delete it and reinstall.
If two tools legitimately conflict, choose one or adjust the completion target in configuration.

Example fix

// before: symlink owned by another install
readlink /usr/local/bin/mytool  # /opt/homebrew/Caskroom/other/1.0/bin/mytool

// after: remove the foreign link and reinstall
rm /usr/local/bin/mytool && mise install cask://my-tool

Defensive patterns

Strategy: validation

Validate before calling

use std::path::Path;
fn link_owned_by_cask(target: &Path, caskroom_prefix: &str) -> bool {
    target
        .read_link()
        .ok()
        .map(|l| l.to_string_lossy().contains(caskroom_prefix))
        .unwrap_or(false)
}

Type guard

fn is_symlink(target: &std::path::Path) -> bool {
    target
        .symlink_metadata()
        .map(|md| md.file_type().is_symlink())
        .unwrap_or(false)
}

Try / catch

// Rust
match install_cask_completion(&cask, &artifacts, &caskroom, &target) {
    Err(e) if e.to_string().contains("already points to") => {
        // inspect readlink(target); remove stale/foreign link, then retry once
    }
    other => other,
}

Prevention

Keep symlink ownership per package: never share one bin path across brew cask and mise cask.
Clean up symlinks after uninstalling the previous manager for a tool.
Watch for stale links to deleted cask versions and remove them.
Resolve existing links with readlink before installing to detect conflicts early.

When it happens

Trigger: Installing a cask whose completion target already is a symlink, but read_link/resolution shows it points to a path that is not this cask's staged artifact, and it is not same_file to the matching appdir artifact source for cask.token.

Common situations: A symlink created by native Homebrew or another version manager points at its own Cellar/Caskroom; a stale symlink survives after the old cask version was deleted; two casks or tools claim the same binary name (e.g. two CLI tools installing the same shim path).

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

AI-assisted analysis of jdx/mise@533346cc37 (2026-09-17). Data as JSON: /api/errors/46d9b5098cb90dff. Report an issue: GitHub.

Appendix: source

Thrown at src/system/packages/brew/cask/mod.rs:2927

        );
    }
    let link_target = std::fs::read_link(target)?;
    let resolved = resolve_symlink_target(target, link_target);
    let token_dir = caskroom_token_dir(&cask.token);
    if path_starts_with_resolved_root(&resolved, &token_dir) {
        return Ok(());
    }
    for completion in &artifacts.completions {
        if completion.target_path()? != target {
            continue;
        }
        if let Some(source) = appdir_artifact_source(&completion.source, &artifacts.apps)?
            && file::same_file(&resolved, &source)
        {
            return Ok(());
        }
    }
    bail!(
        "brew-cask: completion target '{}' already points to '{}' and is not owned by cask '{}'",
        target.display(),
        resolved.display(),
        cask.token
    )
}

fn find_completion_source(
    stage: &Path,
    caskroom: &Path,
    cask: &Cask,
    apps: &[AppArtifact],
    source: &str,
) -> Result<Option<PathBuf>> {
    for root in [caskroom, stage] {
        if let Some(source) = generated_caskroom_artifact(root, cask, source)
            && source.is_file()
        {

View on GitHub (pinned to 533346cc37)