read.markets/app/services/email_service.py
Giorgio Gilestro b055eea1c2 email: split digest renderer to digest_email.py
email_service.py was 428 lines covering three different concerns:
SMTP transport, OTP/welcome rendering (tightly coupled — same brand
template + theme), and digest rendering (a totally different shape
of email, different layout, different copy cadence). The two halves
changed at different cadences and made the file noisy to navigate.

Extracted render_digest_email + _DIGEST_HTML_TEMPLATE +
_strip_html_to_text to app/services/digest_email.py. SMTP transport
and the OTP/welcome surface stay in email_service.py.

Import sites updated: email_digest_job and test_email_render now
import render_digest_email from digest_email. The OTP/welcome
import sites (auth router, branding tests, test_email_service) are
untouched.

No behaviour change — pure relocation. Templates byte-identical.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-27 21:33:06 +02:00

323 lines
13 KiB
Python

"""SMTP-backed transactional email.
Sends multipart/alternative: a plain-text body for accessibility / minimal
clients and an HTML body for richer rendering. Designed for cross-client
robustness:
- Inline styles on every element (Outlook desktop ignores <style> blocks).
- `<style>` block in <head> only carries the prefers-color-scheme media
query for clients that respect it (Apple Mail, Gmail web, Outlook.com).
- Light background by default — dark backgrounds are inconsistently
rendered across clients.
- 520-px max width, monospace stack with fallbacks, no external assets
(no remote images, no web fonts), so the email opens identically with
network off.
When SMTP_SERVER is empty, falls back to writing the payload to stdout —
convenient for local dev that doesn't want a mail server configured.
"""
from __future__ import annotations
from email.message import EmailMessage
import aiosmtplib
from app import branding
from app.config import get_settings
from app.logging import get_logger
log = get_logger("email")
class EmailSendError(RuntimeError):
"""Raised when SMTP submission fails. The caller should surface a
generic error to the user rather than the SMTP details."""
async def send_email(
to: str,
subject: str,
text_body: str,
html_body: str | None = None,
) -> None:
"""Send a (potentially multipart) email. `text_body` is required —
it's the fallback for clients that can't or won't render HTML."""
s = get_settings()
sender = s.SMTP_FROM or s.SMTP_USER or branding.EMAIL_FROM_DEFAULT
msg = EmailMessage()
msg["From"] = sender
msg["To"] = to
msg["Subject"] = subject
msg.set_content(text_body)
if html_body:
msg.add_alternative(html_body, subtype="html")
if not s.SMTP_SERVER:
log.info(
"email.stdout_fallback", to=to, subject=subject,
text_preview=text_body[:120],
multipart=bool(html_body),
)
return
try:
await aiosmtplib.send(
msg,
hostname=s.SMTP_SERVER,
port=s.SMTP_PORT,
username=s.SMTP_USER or None,
password=s.SMTP_PASSWORD or None,
start_tls=s.SMTP_USE_TLS,
timeout=20,
)
log.info("email.sent", to=to, subject=subject)
except Exception as e:
log.error("email.send_failed", to=to, error=str(e)[:200])
raise EmailSendError(f"Failed to send email: {e}") from e
# ---------------------------------------------------------------------------
# OTP email rendering
# ---------------------------------------------------------------------------
_OTP_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">
<meta name="supported-color-schemes" content="light dark">
<title>Your {brand} sign-in code</title>
<style>
@media (prefers-color-scheme: dark) {{
body {{ background:{D_bg} !important; }}
.card {{ background:{D_surface} !important; border-color:{D_border} !important; }}
.h1 {{ color:{D_text} !important; }}
.muted {{ color:{D_muted} !important; }}
.lead {{ color:{D_text} !important; }}
.code {{ background:{D_bg} !important; color:{D_accent} !important;
border-color:{D_accent} !important; }}
.divider {{ border-color:{D_border} !important; }}
}}
@media (max-width: 540px) {{
.card {{ padding:24px 18px !important; }}
.code {{ font-size:26px !important; letter-spacing:0.3em !important; }}
}}
</style>
</head>
<body style="margin:0; padding:24px 12px; background:{L_bg}; font-family:{FONT_MONO}; color:{L_text}; -webkit-font-smoothing:antialiased;">
<div style="display:none; max-height:0; overflow:hidden; mso-hide:all; font-size:1px; line-height:1px; color:{L_bg};">
Your {brand} sign-in code — {code} — expires in {ttl_minutes} minutes.
</div>
<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}
</div>
<div style="height:22px; line-height:22px; font-size:0;">&nbsp;</div>
<div class="h1" style="font-size:17px; font-weight:normal; color:{L_text}; letter-spacing:0.02em;">
Your sign-in code
</div>
<div style="height:16px; line-height:16px; font-size:0;">&nbsp;</div>
<div class="code" style="font-family:{FONT_MONO}; font-size:32px; letter-spacing:0.4em; text-align:center; padding:20px 12px; border:1px solid {L_accent}; background:{L_surface}; color:{L_accent}; user-select:all;">
{code}
</div>
<div style="height:18px; line-height:18px; font-size:0;">&nbsp;</div>
<div class="lead muted" style="font-size:13px; color:{L_muted}; line-height:1.6;">
This code expires in <span style="color:{L_text};">{ttl_minutes} minutes</span>.
If you didn&rsquo;t request it, you can safely ignore this email &mdash; no changes
will be made to any account.
</div>
<div style="height:26px; line-height:26px; font-size:0;">&nbsp;</div>
<div class="divider" 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:10.5px; color:{L_dim}; letter-spacing:0.06em;">
Sent automatically by {brand} &middot; do not reply
</div>
</td></tr>
</table>
</body>
</html>
"""
def _html_template_filled(code: str, ttl_minutes: int) -> str:
"""Substitute palette + content into the OTP HTML template."""
return _OTP_HTML_TEMPLATE.format(
code=code,
ttl_minutes=ttl_minutes,
brand=branding.BRAND_NAME,
brand_upper=branding.BRAND_NAME.upper(),
FONT_MONO=branding.FONT_MONO,
**{f"L_{k.replace('-', '_')}": v for k, v in branding.LIGHT.items()},
**{f"D_{k.replace('-', '_')}": v for k, v in branding.DARK.items()},
)
_OTP_TEXT_TEMPLATE = """\
{brand_upper} — sign in
Your verification code:
{code}
This code expires in {ttl_minutes} minutes.
If you didn't request it, you can safely ignore this email — no changes
will be made to any account.
Sent automatically by {brand} · do not reply
"""
def render_otp_email(code: str, ttl_minutes: int) -> tuple[str, str, str]:
"""Returns (subject, text_body, html_body).
Subject embeds the code so users can read it directly from the inbox
list without opening the message — common practice for OTP emails
(Notion, Substack). The lock-screen exposure tradeoff is minimal:
anyone with phone access who could see the notification could also
open the email."""
subject = f"{branding.BRAND_NAME} sign-in: {code}"
text = _OTP_TEXT_TEMPLATE.format(
code=code,
ttl_minutes=ttl_minutes,
brand=branding.BRAND_NAME,
brand_upper=branding.BRAND_NAME.upper(),
)
html = _html_template_filled(code=code, ttl_minutes=ttl_minutes)
return subject, text, html
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)
# ---------------------------------------------------------------------------
# Welcome email — sent once on first successful login.
# ---------------------------------------------------------------------------
_WELCOME_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">
<meta name="supported-color-schemes" content="light dark">
<title>Welcome to {brand}</title>
<style>
@media (prefers-color-scheme: dark) {{
body {{ background:{D_bg} !important; }}
.card {{ background:{D_surface} !important; border-color:{D_border} !important; }}
.h1 {{ color:{D_text} !important; }}
.muted {{ color:{D_muted} !important; }}
.lead {{ color:{D_text} !important; }}
.divider {{ border-color:{D_border} !important; }}
a {{ color:{D_accent} !important; }}
}}
@media (max-width: 540px) {{
.card {{ padding:24px 18px !important; }}
}}
</style>
</head>
<body style="margin:0; padding:24px 12px; background:{L_bg}; font-family:{FONT_MONO}; color:{L_text}; -webkit-font-smoothing:antialiased;">
<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}
</div>
<div style="height:22px; line-height:22px; font-size:0;">&nbsp;</div>
<div class="h1" style="font-size:17px; font-weight:normal; color:{L_text}; letter-spacing:0.02em;">
Welcome to {brand}.
</div>
<div style="height:14px; line-height:14px; font-size:0;">&nbsp;</div>
<div class="lead muted" style="font-size:13px; color:{L_muted}; line-height:1.65;">
You&rsquo;re signed in. The dashboard is at
<a href="{app_url}" style="color:{L_accent}; text-decoration:none;">{app_url_short}</a> &mdash;
a rolling news feed, cross-asset indicator panels, and a written
strategic read of the session, all updated through the day.
</div>
<div style="height:20px; line-height:20px; font-size:0;">&nbsp;</div>
<div class="divider" style="border-top:1px solid {L_border};"></div>
<div style="height:18px; line-height:18px; font-size:0;">&nbsp;</div>
<div class="h1" style="font-size:14px; font-weight:normal; color:{L_text};">
About the email digest
</div>
<div style="height:10px; line-height:10px; font-size:0;">&nbsp;</div>
<div class="lead muted" style="font-size:13px; color:{L_muted}; line-height:1.65;">
We send one Sunday digest to every account &mdash; the week behind +
the week ahead. Paid subscribers also get a short daily digest
(Mon&ndash;Sat), each a ~600-word read of the session.
You&rsquo;re opted in by default; you can switch the digest off
at any time on the
<a href="{settings_url}" style="color:{L_accent}; text-decoration:none;">Settings page</a>,
or use the one-click unsubscribe link in every digest email.
</div>
<div style="height:20px; line-height:20px; font-size:0;">&nbsp;</div>
<div class="divider" 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:10.5px; color:{L_dim}; letter-spacing:0.06em;">
Sent automatically by {brand} &middot; do not reply
</div>
</td></tr>
</table>
</body>
</html>
"""
_WELCOME_TEXT_TEMPLATE = """\
{brand_upper} — welcome
You're signed in. The dashboard is at {app_url}: a rolling news feed,
cross-asset indicator panels, and a written strategic read of the
session, all updated through the day.
About the email digest
----------------------
We send one Sunday digest to every account (the week behind + the
week ahead). Paid subscribers also get a short daily digest (Mon-Sat),
each a ~600-word read of the session.
You're opted in by default; switch it off any time at {settings_url},
or use the one-click unsubscribe link in every digest email.
Sent automatically by {brand} · do not reply
"""
def render_welcome_email() -> tuple[str, str, str]:
"""Returns (subject, text_body, html_body) for the post-signup welcome.
Single-shot email, sent the first time a user successfully verifies
an OTP. Explains the digest (which is opt-in by default) and how to
turn it off — replaces the old verify-page checkbox which appeared
on every login and was misleading."""
subject = f"Welcome to {branding.BRAND_NAME}"
fmt = dict(
brand=branding.BRAND_NAME,
brand_upper=branding.BRAND_NAME.upper(),
app_url=branding.APP_URL,
app_url_short=branding.APP_URL.replace("https://", "").replace("http://", ""),
settings_url=f"{branding.APP_URL}/settings",
FONT_MONO=branding.FONT_MONO,
**{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 = _WELCOME_TEXT_TEMPLATE.format(**fmt)
html = _WELCOME_HTML_TEMPLATE.format(**fmt)
return subject, text, html
async def send_welcome_email(to: str) -> None:
subject, text, html = render_welcome_email()
await send_email(to, subject, text, html_body=html)