Unclear It is not clear whether helpers could already print headers before, or whether this is newly possible.
What
A credentialHelper is a program Claude Code runs to get the credentials for a plugin marketplace (a place plugins are installed from). For url marketplace sources, the documentation now says the helper may print HTTP headers as a JSON object. Before, it described only the helper's output being used as the Authorization header.
Why
Admins can authenticate to a marketplace that needs custom headers, not just a single Authorization header.
Names in the bundlecredentialHelper
Documented inclaude-docs/cowork/changelog
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The writer flagged doubt
It is not clear whether helpers could already print headers before, or whether this is newly possible.