[leemour]

What

• mail <profile> messages send --html reads the text (argument or stdin) as HTML.
• The plain-text part is made from the HTML with cli-core's htmlToText. The mail goes as multipart/alternative, and as multipart/mixed around that when files are attached.
• Draft gains an optional html field, and build passes it to nodemailer. The answer adds html_chars.
• --html together with --reply-to is refused (validation_error). A reply quotes its original as plain text, so an HTML part would not have the quote.

Why

This is the mail-cli step of the digest format plan (max-cli/docs_ai/plans/2026-11-07-digest-format.md, section 7 step 3). Today the email route sends the morning digest as raw Markdown, because messages send can only send plain text. With this flag, the cli-core renderer (and memo --deliver-to) can send HTML.

Not in this PR

• --text-file <file> for a hand-written plain part. The plan mentions it as an option. It is not needed until a renderer makes its own plain text.
• HTML for replies, forwards and drafts.

How tested

• New test in src/send.test.ts: sends synthetic HTML through the fake SMTP server and checks multipart/alternative, the decoded plain part and the HTML part. It also checks that --html with --reply-to is refused and nothing is sent.
• pnpm vitest run --maxWorkers=1: 26 files, 335 tests pass.
• pnpm typecheck, pnpm lint (no new warnings), pnpm docs:check, pnpm contracts:check and pnpm test:matrix:check all pass.
• docs/commands.md and docs/dev/test-matrix.md were regenerated.
• Not tested: a real send through Gmail or another real SMTP server, and how the mail looks in a real mail client.

🤖 Generated with Claude Code