The secret store outlives the sandbox, so recreating one to change its image
or add a profile does not lose the token. Prompting for a replacement anyway
made --replace impractical and trained the habit of minting tokens that are
never revoked.
Only a token scoped to this sandbox counts. A global one would authenticate
the agent too, but reaching every repository it can reach is what this task
exists to prevent. The token command still always prompts; it is the way to
replace an expired or revoked token.