Backoff returns a value in [0, maxDelay] that increases exponentially with retries, starting from baseDelay.

Clean removes left-over containers, networks, and volumes from a previous run of the local builder.

ParseSubstitutionsFlag parses a substitutions string into a map.

RefreshDuration calculates when to refresh the access token.

SubstituteAndValidate merges the substitutions from the build config and the local flag, validates them and the build.

TokenTransport is a RoundTripper that automatically applies OAuth credentials from the token source.