Read markdown from standard input when the filename is -

[mapitman]

What

mdview - now reads the markdown from standard input instead of from a file.

Why

Piping markdown in avoids writing it to disk first. That matters when the content is decrypted or generated on the fly, where a temporary plaintext file is undesirable:

age -d -i ~/.config/age/key.txt notes.md.age | mdview -

Previously the only option was to decrypt to a temp file, view it, then delete it, which leaves plaintext on disk for the lifetime of the command.

How

When the first positional argument is -, main() reads with io.ReadAll(os.Stdin). Otherwise the existing os.ReadFile path is unchanged.

Relative image paths resolve against the working directory in the stdin case, since there is no input file to anchor them to. The rest of the pipeline (image inlining, Goldmark parsing, title extraction, mermaid embedding, templating) is untouched.

Verification

Checked manually, as the repo has no test suite:

• stdin and file input produce byte-identical HTML for the same content
• H1 title extraction works through the pipe
• empty stdin renders an empty document rather than crashing
• -b/-bare works via stdin
• missing-file errors are unchanged
• end to end: age -d ... | mdview - renders the decrypted content

Also updated

mdview.1.md, README.md, and CLAUDE.md to document the new form.

No CHANGELOG entry: entries there are per-release with dates and PR numbers, so this belongs to the next release rather than the branch.

Two pre-existing issues were left alone, both in code this branch does not touch: a go vet redundant-newline warning in the Snap hint, and some gofmt comment-alignment drift.