Giorgio Gilestro
a4e585fbfb
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>
304 lines
11 KiB
Python
304 lines
11 KiB
Python
"""SMTP-backed transactional email.
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Sends multipart/alternative: a plain-text body for accessibility / minimal
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clients and an HTML body for richer rendering. Designed for cross-client
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robustness:
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- Inline styles on every element (Outlook desktop ignores <style> blocks).
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- `<style>` block in <head> only carries the prefers-color-scheme media
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query for clients that respect it (Apple Mail, Gmail web, Outlook.com).
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- Light background by default — dark backgrounds are inconsistently
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rendered across clients.
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- 520-px max width, monospace stack with fallbacks, no external assets
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(no remote images, no web fonts), so the email opens identically with
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network off.
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When SMTP_SERVER is empty, falls back to writing the payload to stdout —
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convenient for local dev that doesn't want a mail server configured.
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"""
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from __future__ import annotations
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import html as _html_lib
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import re as _re
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from email.message import EmailMessage
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import aiosmtplib
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from app import branding
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from app.config import get_settings
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from app.logging import get_logger
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log = get_logger("email")
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class EmailSendError(RuntimeError):
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"""Raised when SMTP submission fails. The caller should surface a
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generic error to the user rather than the SMTP details."""
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async def send_email(
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to: str,
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subject: str,
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text_body: str,
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html_body: str | None = None,
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) -> None:
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"""Send a (potentially multipart) email. `text_body` is required —
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it's the fallback for clients that can't or won't render HTML."""
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s = get_settings()
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sender = s.SMTP_FROM or s.SMTP_USER or branding.EMAIL_FROM_DEFAULT
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msg = EmailMessage()
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msg["From"] = sender
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msg["To"] = to
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msg["Subject"] = subject
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msg.set_content(text_body)
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if html_body:
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msg.add_alternative(html_body, subtype="html")
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if not s.SMTP_SERVER:
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log.info(
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"email.stdout_fallback", to=to, subject=subject,
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text_preview=text_body[:120],
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multipart=bool(html_body),
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)
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return
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try:
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await aiosmtplib.send(
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msg,
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hostname=s.SMTP_SERVER,
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port=s.SMTP_PORT,
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username=s.SMTP_USER or None,
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password=s.SMTP_PASSWORD or None,
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start_tls=s.SMTP_USE_TLS,
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timeout=20,
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)
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log.info("email.sent", to=to, subject=subject)
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except Exception as e:
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log.error("email.send_failed", to=to, error=str(e)[:200])
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raise EmailSendError(f"Failed to send email: {e}") from e
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# ---------------------------------------------------------------------------
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# OTP email rendering
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# ---------------------------------------------------------------------------
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_OTP_HTML_TEMPLATE = """\
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<meta name="color-scheme" content="light dark">
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<meta name="supported-color-schemes" content="light dark">
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<title>Your {brand} sign-in code</title>
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<style>
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@media (prefers-color-scheme: dark) {{
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body {{ background:{D_bg} !important; }}
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.card {{ background:{D_surface} !important; border-color:{D_border} !important; }}
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.h1 {{ color:{D_text} !important; }}
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.muted {{ color:{D_muted} !important; }}
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.lead {{ color:{D_text} !important; }}
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.code {{ background:{D_bg} !important; color:{D_accent} !important;
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border-color:{D_accent} !important; }}
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.divider {{ border-color:{D_border} !important; }}
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}}
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@media (max-width: 540px) {{
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.card {{ padding:24px 18px !important; }}
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.code {{ font-size:26px !important; letter-spacing:0.3em !important; }}
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}}
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</style>
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</head>
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<body style="margin:0; padding:24px 12px; background:{L_bg}; font-family:{FONT_MONO}; color:{L_text}; -webkit-font-smoothing:antialiased;">
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<div style="display:none; max-height:0; overflow:hidden; mso-hide:all; font-size:1px; line-height:1px; color:{L_bg};">
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Your {brand} sign-in code — {code} — expires in {ttl_minutes} minutes.
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</div>
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<table role="presentation" cellpadding="0" cellspacing="0" border="0" align="center" width="100%" style="max-width:520px; margin:0 auto; border-collapse:separate;">
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<tr><td class="card" style="background:{L_surface}; border:1px solid {L_border}; padding:32px 28px;">
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<div class="muted" style="font-size:11px; letter-spacing:0.32em; color:{L_muted}; text-transform:uppercase;">
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▰ {brand_upper}
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</div>
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<div style="height:22px; line-height:22px; font-size:0;"> </div>
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<div class="h1" style="font-size:17px; font-weight:normal; color:{L_text}; letter-spacing:0.02em;">
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Your sign-in code
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</div>
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<div style="height:16px; line-height:16px; font-size:0;"> </div>
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<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;">
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{code}
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</div>
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<div style="height:18px; line-height:18px; font-size:0;"> </div>
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<div class="lead muted" style="font-size:13px; color:{L_muted}; line-height:1.6;">
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This code expires in <span style="color:{L_text};">{ttl_minutes} minutes</span>.
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If you didn’t request it, you can safely ignore this email — no changes
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will be made to any account.
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</div>
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<div style="height:26px; line-height:26px; font-size:0;"> </div>
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<div class="divider" style="border-top:1px solid {L_border};"></div>
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<div style="height:14px; line-height:14px; font-size:0;"> </div>
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<div class="muted" style="font-size:10.5px; color:{L_dim}; letter-spacing:0.06em;">
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Sent automatically by {brand} · do not reply
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</div>
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</td></tr>
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</table>
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</body>
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</html>
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"""
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def _html_template_filled(code: str, ttl_minutes: int) -> str:
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"""Substitute palette + content into the OTP HTML template."""
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return _OTP_HTML_TEMPLATE.format(
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code=code,
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ttl_minutes=ttl_minutes,
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brand=branding.BRAND_NAME,
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brand_upper=branding.BRAND_NAME.upper(),
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FONT_MONO=branding.FONT_MONO,
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**{f"L_{k.replace('-', '_')}": v for k, v in branding.LIGHT.items()},
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**{f"D_{k.replace('-', '_')}": v for k, v in branding.DARK.items()},
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)
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_OTP_TEXT_TEMPLATE = """\
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{brand_upper} — sign in
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Your verification code:
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{code}
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This code expires in {ttl_minutes} minutes.
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If you didn't request it, you can safely ignore this email — no changes
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will be made to any account.
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—
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Sent automatically by {brand} · do not reply
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"""
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def render_otp_email(code: str, ttl_minutes: int) -> tuple[str, str, str]:
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"""Returns (subject, text_body, html_body).
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Subject embeds the code so users can read it directly from the inbox
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list without opening the message — common practice for OTP emails
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(Notion, Substack). The lock-screen exposure tradeoff is minimal:
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anyone with phone access who could see the notification could also
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open the email."""
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subject = f"{branding.BRAND_NAME} sign-in: {code}"
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text = _OTP_TEXT_TEMPLATE.format(
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code=code,
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ttl_minutes=ttl_minutes,
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brand=branding.BRAND_NAME,
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brand_upper=branding.BRAND_NAME.upper(),
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)
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html = _html_template_filled(code=code, ttl_minutes=ttl_minutes)
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return subject, text, html
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async def send_otp(to: str, code: str, ttl_minutes: int) -> None:
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subject, text, html = render_otp_email(code, ttl_minutes)
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await send_email(to, subject, text, html_body=html)
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# ---------------------------------------------------------------------------
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# Digest email rendering
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# ---------------------------------------------------------------------------
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_DIGEST_HTML_TEMPLATE = """\
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<meta name="color-scheme" content="light dark">
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<title>{brand} — {label}</title>
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<style>
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@media (prefers-color-scheme: dark) {{
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body {{ background:{D_bg} !important; }}
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.card {{ background:{D_surface} !important; border-color:{D_border} !important; }}
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.h1, p, li {{ color:{D_text} !important; }}
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.muted {{ color:{D_muted} !important; }}
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a {{ color:{D_accent} !important; }}
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}}
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</style>
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</head>
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<body style="margin:0; padding:24px 12px; background:{L_bg}; font-family:{FONT_MONO}; color:{L_text};">
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<table role="presentation" cellpadding="0" cellspacing="0" border="0" align="center" width="100%" style="max-width:520px; margin:0 auto; border-collapse:separate;">
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<tr><td class="card" style="background:{L_surface}; border:1px solid {L_border}; padding:32px 28px;">
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<div class="muted" style="font-size:11px; letter-spacing:0.32em; color:{L_muted}; text-transform:uppercase;">
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▰ {brand_upper} · {label_upper}
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</div>
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<div style="height:20px; line-height:20px; font-size:0;"> </div>
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<div class="content" style="font-size:14px; line-height:1.65; color:{L_text};">
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{content_html}
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</div>
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<div style="height:24px; line-height:24px; font-size:0;"> </div>
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<div style="border-top:1px solid {L_border};"></div>
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<div style="height:14px; line-height:14px; font-size:0;"> </div>
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<div class="muted" style="font-size:11px; color:{L_muted};">
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<a href="{unsubscribe_url}" style="color:{L_accent};">Unsubscribe in one click</a>
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· <a href="{settings_url}" style="color:{L_accent};">Manage preferences</a>
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</div>
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</td></tr>
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</table>
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</body>
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</html>
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"""
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def _strip_html_to_text(html_body: str) -> str:
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"""Best-effort HTML → plain text for the multipart fallback. We don't
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need perfection — just readable prose for clients that won't render
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HTML."""
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text = _re.sub(r"(?i)<(/(p|h[1-6]|li|ul|ol)|br\s*/?)>", "\n", html_body)
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text = _re.sub(r"<[^>]+>", "", text)
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text = _html_lib.unescape(text)
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text = _re.sub(r"\n{3,}", "\n\n", text)
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return text.strip()
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def render_digest_email(
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*,
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kind: str,
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date_str: str,
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content_html: str,
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unsubscribe_url: str,
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settings_url: str,
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) -> tuple[str, str, str]:
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"""Returns (subject, text_body, html_body) for a digest email.
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`kind` is "daily" or "weekly". Anything else raises ValueError."""
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if kind == "daily":
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label = "Daily"
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subject = f"{branding.BRAND_NAME} · Daily — {date_str}"
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elif kind == "weekly":
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label = "Weekly recap"
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subject = f"{branding.BRAND_NAME} · Weekly recap — {date_str}"
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else:
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raise ValueError(f"unknown digest kind: {kind!r}")
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html_body = _DIGEST_HTML_TEMPLATE.format(
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brand=branding.BRAND_NAME,
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brand_upper=branding.BRAND_NAME.upper(),
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label=label,
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label_upper=label.upper(),
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FONT_MONO=branding.FONT_MONO,
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content_html=content_html,
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unsubscribe_url=unsubscribe_url,
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settings_url=settings_url,
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**{f"L_{k.replace('-', '_')}": v for k, v in branding.LIGHT.items()},
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**{f"D_{k.replace('-', '_')}": v for k, v in branding.DARK.items()},
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)
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text_lines = [
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f"{branding.BRAND_NAME} — {label}",
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date_str,
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"",
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_strip_html_to_text(content_html),
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"",
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f"Unsubscribe: {unsubscribe_url}",
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f"Manage preferences: {settings_url}",
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]
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text_body = "\n".join(text_lines)
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return subject, text_body, html_body
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