email: render_digest_email — multipart digest template

Adds render_digest_email(kind, date_str, content_html, unsubscribe_url,
settings_url) -> tuple[str, str, str] to email_service.py, following the
same contract as render_otp_email. Includes _DIGEST_HTML_TEMPLATE with
light/dark palette from branding and _strip_html_to_text for the plain-text
fallback. Unit tests in tests/test_email_render.py cover daily, weekly, and
invalid-kind cases.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Giorgio Gilestro 2026-05-25 23:02:05 +02:00
parent 1391f15c28
commit a4e585fbfb
2 changed files with 150 additions and 0 deletions

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@ -18,6 +18,8 @@ convenient for local dev that doesn't want a mail server configured.
"""
from __future__ import annotations
import html as _html_lib
import re as _re
from email.message import EmailMessage
import aiosmtplib
@ -196,3 +198,107 @@ def render_otp_email(code: str, ttl_minutes: int) -> tuple[str, str, str]:
async def send_otp(to: str, code: str, ttl_minutes: int) -> None:
subject, text, html = render_otp_email(code, ttl_minutes)
await send_email(to, subject, text, html_body=html)
# ---------------------------------------------------------------------------
# Digest email rendering
# ---------------------------------------------------------------------------
_DIGEST_HTML_TEMPLATE = """\
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="color-scheme" content="light dark">
<title>{brand} {label}</title>
<style>
@media (prefers-color-scheme: dark) {{
body {{ background:{D_bg} !important; }}
.card {{ background:{D_surface} !important; border-color:{D_border} !important; }}
.h1, p, li {{ color:{D_text} !important; }}
.muted {{ color:{D_muted} !important; }}
a {{ color:{D_accent} !important; }}
}}
</style>
</head>
<body style="margin:0; padding:24px 12px; background:{L_bg}; font-family:{FONT_MONO}; color:{L_text};">
<table role="presentation" cellpadding="0" cellspacing="0" border="0" align="center" width="100%" style="max-width:520px; margin:0 auto; border-collapse:separate;">
<tr><td class="card" style="background:{L_surface}; border:1px solid {L_border}; padding:32px 28px;">
<div class="muted" style="font-size:11px; letter-spacing:0.32em; color:{L_muted}; text-transform:uppercase;">
&#9648;&nbsp;{brand_upper} &middot; {label_upper}
</div>
<div style="height:20px; line-height:20px; font-size:0;">&nbsp;</div>
<div class="content" style="font-size:14px; line-height:1.65; color:{L_text};">
{content_html}
</div>
<div style="height:24px; line-height:24px; font-size:0;">&nbsp;</div>
<div style="border-top:1px solid {L_border};"></div>
<div style="height:14px; line-height:14px; font-size:0;">&nbsp;</div>
<div class="muted" style="font-size:11px; color:{L_muted};">
<a href="{unsubscribe_url}" style="color:{L_accent};">Unsubscribe in one click</a>
&middot; <a href="{settings_url}" style="color:{L_accent};">Manage preferences</a>
</div>
</td></tr>
</table>
</body>
</html>
"""
def _strip_html_to_text(html_body: str) -> str:
"""Best-effort HTML → plain text for the multipart fallback. We don't
need perfection just readable prose for clients that won't render
HTML."""
text = _re.sub(r"(?i)<(/(p|h[1-6]|li|ul|ol)|br\s*/?)>", "\n", html_body)
text = _re.sub(r"<[^>]+>", "", text)
text = _html_lib.unescape(text)
text = _re.sub(r"\n{3,}", "\n\n", text)
return text.strip()
def render_digest_email(
*,
kind: str,
date_str: str,
content_html: str,
unsubscribe_url: str,
settings_url: str,
) -> tuple[str, str, str]:
"""Returns (subject, text_body, html_body) for a digest email.
`kind` is "daily" or "weekly". Anything else raises ValueError."""
if kind == "daily":
label = "Daily"
subject = f"{branding.BRAND_NAME} · Daily — {date_str}"
elif kind == "weekly":
label = "Weekly recap"
subject = f"{branding.BRAND_NAME} · Weekly recap — {date_str}"
else:
raise ValueError(f"unknown digest kind: {kind!r}")
html_body = _DIGEST_HTML_TEMPLATE.format(
brand=branding.BRAND_NAME,
brand_upper=branding.BRAND_NAME.upper(),
label=label,
label_upper=label.upper(),
FONT_MONO=branding.FONT_MONO,
content_html=content_html,
unsubscribe_url=unsubscribe_url,
settings_url=settings_url,
**{f"L_{k.replace('-', '_')}": v for k, v in branding.LIGHT.items()},
**{f"D_{k.replace('-', '_')}": v for k, v in branding.DARK.items()},
)
text_lines = [
f"{branding.BRAND_NAME}{label}",
date_str,
"",
_strip_html_to_text(content_html),
"",
f"Unsubscribe: {unsubscribe_url}",
f"Manage preferences: {settings_url}",
]
text_body = "\n".join(text_lines)
return subject, text_body, html_body

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@ -0,0 +1,44 @@
"""Unit tests for render_digest_email."""
from __future__ import annotations
from app.services.email_service import render_digest_email
def test_daily_subject_and_bodies():
subj, text, html = render_digest_email(
kind="daily",
date_str="2026-05-25",
content_html="<p>Markets did stuff today.</p>",
unsubscribe_url="https://read.markets/email/unsubscribe?token=abc",
settings_url="https://read.markets/settings",
)
assert "Daily" in subj
assert "2026-05-25" in subj
assert "Markets did stuff today" in html
assert "abc" in html # unsubscribe link landed
assert "/settings" in html
# Plain-text fallback strips HTML.
assert "<p>" not in text
assert "Markets did stuff today" in text
def test_weekly_subject_says_recap():
subj, _, _ = render_digest_email(
kind="weekly",
date_str="2026-05-25",
content_html="<p>x</p>",
unsubscribe_url="https://x/u",
settings_url="https://x/s",
)
assert "Weekly" in subj
assert "recap" in subj.lower()
def test_invalid_kind_raises():
import pytest
with pytest.raises(ValueError):
render_digest_email(
kind="bogus", date_str="2026-05-25",
content_html="<p>x</p>",
unsubscribe_url="u", settings_url="s",
)