"clear-cache" ignores "cache-dir" defined in "composer.json"

[JanWennrichPCSG]

My composer.json:

{
    "name": "jan/composer-test",
    "require": {
        "ramsey/uuid": "^4.7"
    },
    "autoload": {
        "psr-4": {
            "Jan\\ComposerTest\\": "src/"
        }
    },
    "authors": [
        {
            "name": "Jan Wennrich",
            "email": "jan.wennrich@pcsg.de"
        }
    ],
    "config": {
        "cache-dir": "/tmp/composer-cache"
    }
}

Output of composer diagnose:

Composer could not detect the root package (jan/composer-test) version, defaulting to '1.0.0'. See https://getcomposer.org/root-version
Checking composer.json: WARNING
No license specified, it is recommended to do so. For closed-source software you may use "proprietary" as license.
Checking platform settings: OK
Checking git settings: OK git version 2.39.3
Checking http connectivity to packagist: OK
Checking https connectivity to packagist: OK
Checking github.com rate limit: OK
Checking disk free space: OK
Checking pubkeys:
Tags Public Key Fingerprint: 57815BA2 7E54DC31 7ECC7CC5 573090D0  87719BA6 8F3BB723 4E5D42D0 84A14642
Dev Public Key Fingerprint: 4AC45767 E5EC2265 2F0C1167 CBBB8A2B  0C708369 153E328C AD90147D AFE50952
OK
Checking Composer version: OK
Checking Composer and its dependencies for vulnerabilities: OK
Composer version: 2.7.2
PHP version: 8.2.17
PHP binary path: /opt/homebrew/Cellar/php@8.2/8.2.17/bin/php
OpenSSL version: OpenSSL 3.2.1 30 Jan 2024
cURL version: 8.7.1 libz 1.2.12 ssl (SecureTransport) OpenSSL/3.2.1
zip: extension present, unzip present, 7-Zip present (7z)

When I run this command:

composer cc -vvv

I get the following output:

Running 2.7.2 (2024-03-11 17:12:18) with PHP 8.2.17 on Darwin / 23.4.0
Reading ./composer.json (/private/tmp/composer-test/composer.json)
Loading config file ./composer.json (/private/tmp/composer-test/composer.json)
Checked CA file /opt/homebrew/etc/ca-certificates/cert.pem: valid
Executing command (/private/tmp/composer-test): 'git' 'branch' '-a' '--no-color' '--no-abbrev' '-v'
Executing command (/private/tmp/composer-test): git describe --exact-match --tags
Executing command (CWD): git --version
Executing command (/private/tmp/composer-test): git log --pretty="%H" -n1 HEAD --no-show-signature
Executing command (/private/tmp/composer-test): hg branch
Executing command (/private/tmp/composer-test): fossil branch list
Executing command (/private/tmp/composer-test): fossil tag list
Executing command (/private/tmp/composer-test): svn info --xml
Composer could not detect the root package (jan/composer-test) version, defaulting to '1.0.0'. See https://getcomposer.org/root-version
Failed to initialize global composer: Composer could not find the config file: /Users/jan/.composer/composer.json

Reading ./composer.lock (/private/tmp/composer-test/composer.lock)
Reading /private/tmp/composer-test/vendor/composer/installed.json
Cache directory does not exist (cache-vcs-dir):
Cache directory does not exist (cache-repo-dir):
Clearing cache (cache-files-dir): /Users/jan/Library/Caches/composer/files
Clearing cache (cache-dir): /Users/jan/Library/Caches/composer
All caches cleared.

And I expected this to happen:

The cache directory (/tmp/composer-cache) - as defined in the config.cache-dir property in the composer.json - should be cleared.

Instead my global cache directory (/Users/jan/Library/Caches/composer) is cleared.

When installing packages, I see the /tmp/composer-cache directory being populated with files.

The config --list command also outputs that directory as the cache-dir config value:

❯ composer config --list
Composer could not detect the root package (jan/composer-test) version, defaulting to '1.0.0'. See https://getcomposer.org/root-version
[repositories.packagist.org.type] composer
[repositories.packagist.org.url] https://repo.packagist.org
[process-timeout] 300
[use-include-path] false
[use-parent-dir] prompt
[preferred-install] dist
[audit.abandoned] fail
[notify-on-install] true
[github-protocols] [https, ssh]
[gitlab-protocol]
[vendor-dir] vendor (/private/tmp/composer-test/vendor)
[bin-dir] {$vendor-dir}/bin (/private/tmp/composer-test/vendor/bin)
[cache-dir] /tmp/composer-cache
[data-dir] /Users/jan/.composer
[cache-files-dir] {$cache-dir}/files (/tmp/composer-cache/files)
[cache-repo-dir] {$cache-dir}/repo (/tmp/composer-cache/repo)
[cache-vcs-dir] {$cache-dir}/vcs (/tmp/composer-cache/vcs)
[cache-ttl] 15552000
[cache-files-ttl] 15552000
[cache-files-maxsize] 300MiB (314572800)
[cache-read-only] false
[bin-compat] auto
[discard-changes] false
[autoloader-suffix]
[sort-packages] false
[optimize-autoloader] false
[classmap-authoritative] false
[apcu-autoloader] false
[prepend-autoloader] true
[github-domains] [github.com]
[bitbucket-expose-hostname] true
[disable-tls] false
[secure-http] true
[cafile]
[capath]
[github-expose-hostname] true
[gitlab-domains] [gitlab.com]
[store-auths] prompt
[archive-format] tar
[archive-dir] .
[htaccess-protect] true
[use-github-api] true
[lock] true
[platform-check] php-only
[home] /Users/jan/.composer