Function symlinkDataDir

ai/scripts/migrations/bootstrapWorktree.mjs:346–403

({
    mainCheckout,
    projectRoot,
    subdirs = DATA_SUBDIRS_TO_LINK,
    force   = false,
    log     = console.log
})

 * @throws {Error} When any subdir's dst is a non-symlink directory and `force` is false. The error message names the offending subdir.
 */
export async function symlinkDataDir({
    mainCheckout,
    projectRoot,
    subdirs = DATA_SUBDIRS_TO_LINK,
    force   = false,
    log     = console.log
}) {
    const result = {linked: [], alreadyLinked: [], clobbered: [], skippedNoSource: [], mainCheckout: false};

    if (path.resolve(projectRoot) === path.resolve(mainCheckout)) {
        log(`symlink skip (main checkout): no per-subdir action`);
        result.mainCheckout = true;
        return result;
    }

    // Ensure the parent .neo-ai-data/ exists as a regular dir; we never symlink the parent.
    // This preserves the git-tracked concepts/ subdir already present in the worktree.
    const parentDst = path.join(projectRoot, '.neo-ai-data');
    await fs.mkdir(parentDst, {recursive: true});

    for (const subdir of subdirs) {
        const src   = path.join(mainCheckout, '.neo-ai-data', subdir);
        const dst   = path.join(parentDst, subdir);
        const lstat = await fs.lstat(dst).catch(() => null);

        if (lstat?.isSymbolicLink()) {
            log(`symlink skip (already linked): ${subdir}`);
            result.alreadyLinked.push(subdir);
            continue;
        }

        // Skip if canonical lacks the subdir — graceful for fresh repos.
        const srcExists = await exists(src);
        if (!srcExists) {
            log(`symlink skip (no source in main checkout): ${subdir}`);
            result.skippedNoSource.push(subdir);
            continue;
        }

        if (lstat?.isDirectory()) {
            if (!force) {
                throw new Error(
                    `Refusing to replace non-symlink ${dst}; pass force=true (CLI --force) to opt in. ` +
                    `This directory contains local data that would be lost.`
                );
            }
            log(`symlink clobber (force=true): removing ${subdir}`);
            await fs.rm(dst, {recursive: true, force: true});
            result.clobbered.push(subdir);
        }

        await fs.symlink(src, dst, 'dir');
        log(`symlinked: ${subdir} → ${src}`);
        result.linked.push(subdir);
    }

    return result;
}