TDD step 7: read_http executes the optional http extension point behind
an injectable transport seam (urllib_get is the only socket path; the
suite runs socket-free against a mock). credential_ref resolves from the
environment at run time, fail-fast before any transport call; the secret
rides in the Authorization header only. Explicit single-slash URL join,
CRLF-to-LF normalization, LF line-count cap (missing trailing newline
still counts), and code-fence-marker rejection. materialize_bundle
renders the body as a verbatim fenced block; the §8 gate test asserts
zero transport calls without the opt-in.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QeqhJpYQyghASjiJo5EhGg
