Preview composed HTML in a browser before sending

Writes composed HTML to a local file and opens it in the default browser so markdown rendering issues (mis-nested links, stray backticks, unintended list formatting, signature layout) can be caught before creating a Gmail draft.

Usage

mc_preview(
  html,
  path = file.path(tools::R_user_dir("mc", "cache"), "preview.html"),
  open = TRUE
)

Arguments

html: Either a character string of HTML (e.g. from mc_compose()) or a path to a .md draft file. A .md path is detected by the combination of endsWith(x, ".md") and file.exists(x).
path: File path to write the preview to. Defaults to a stable location under tools::R_user_dir() (mc/cache/preview.html) so the file persists after the R session exits and can be opened manually.
open: Logical. If TRUE (default), open the file with utils::browseURL(). When FALSE, only write the file.

Value

The file path, invisibly.

Details

Accepts either a raw HTML string or a path to a .md draft. When a .md path is passed, the frontmatter envelope (To / Cc / Subject / Thread / Attachments) is rendered above the body so recipient or subject mistakes are visible too.

Examples

if (FALSE) { # \dontrun{
# From raw HTML
html <- mc_compose("communications/project/draft.md")
mc_preview(html)

# Directly from a frontmattered .md — shows envelope above body
mc_preview("communications/20260413_cindy_newsletter_draft.md")
} # }