Implement Python email agent with multi-model AI support

Adds a complete email-based registration agent for Spielgruppe Pumuckl
based on the OpenSpec define-project-scope specifications.

Architecture
- Channel-agnostic EmailAgent core — no email-specific code in business logic
- Pluggable AI provider layer: Anthropic (Claude) and OpenAI (GPT) supported
  via a shared LLMProvider interface; switch with AI_PROVIDER env var
- IMAP polling for inbound emails with thread-tracking via email headers
  (Message-ID / In-Reply-To / References)
- SMTP for outbound replies and admin notifications
- File-based JSON storage for conversation state and completed registrations
- Admin-editable knowledge-base loaded from markdown files at startup

Key files
  src/config.py                  — env-var configuration
  src/providers/base.py          — abstract LLMProvider
  src/providers/anthropic_provider.py — Claude backend
  src/providers/openai_provider.py    — OpenAI backend
  src/agent/core.py              — EmailAgent orchestrator
  src/agent/prompts.py           — system prompt builder (KB + registration state)
  src/models/registration.py     — RegistrationData matching the JSON schema
  src/models/conversation.py     — ConversationState persisted per thread
  src/channels/email_channel.py  — IMAP/SMTP I/O + quoted-text stripping
  src/storage/json_store.py      — conversation & registration persistence
  src/notifications/notifier.py  — admin notification routing by playgroup type
  main.py                        — polling entry point
  requirements.txt               — anthropic, openai, python-dotenv, jsonschema
  .env.example                   — configuration template

https://claude.ai/code/session_01HaUFs7SaLD5SoiuGCY27Tw
This commit is contained in:
Claude
2026-02-20 20:17:00 +00:00
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"""IMAP / SMTP email channel adapter.
Handles:
- Polling the inbox for unread messages (IMAP)
- Thread tracking via Message-ID / In-Reply-To / References headers
- Sending reply emails (SMTP) with proper threading headers
- Stripping quoted reply text so the agent only sees the new content
"""
import email
import email.header
import email.utils
import imaplib
import logging
import re
import smtplib
import time
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from typing import Optional
logger = logging.getLogger(__name__)
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _decode_header(value: str) -> str:
"""Decode an RFC-2047 encoded email header value."""
parts = email.header.decode_header(value or "")
decoded = []
for part, charset in parts:
if isinstance(part, bytes):
decoded.append(part.decode(charset or "utf-8", errors="replace"))
else:
decoded.append(part)
return "".join(decoded)
def _extract_text(msg: email.message.Message) -> str:
"""Extract the plain-text body from a (potentially multi-part) message."""
if msg.is_multipart():
for part in msg.walk():
if (
part.get_content_type() == "text/plain"
and "attachment" not in str(part.get("Content-Disposition", ""))
):
charset = part.get_content_charset() or "utf-8"
payload = part.get_payload(decode=True)
if payload:
return payload.decode(charset, errors="replace")
else:
charset = msg.get_content_charset() or "utf-8"
payload = msg.get_payload(decode=True)
if payload:
return payload.decode(charset, errors="replace")
return ""
def _strip_quoted_text(text: str) -> str:
"""Remove quoted reply text from the email body.
Heuristics:
- Drop lines starting with ">"
- Stop at common reply-separator patterns
"""
lines = text.splitlines()
result: list[str] = []
for line in lines:
stripped = line.strip()
if stripped.startswith(">"):
continue
# Common separators used by email clients
if re.match(r"^-{3,}|^_{3,}|^={3,}", stripped):
break
if re.match(r"^On .+ wrote:$", stripped):
break
if re.match(r"^Am .+ schrieb .+:$", stripped): # German Outlook/Thunderbird
break
if "-----Original Message-----" in stripped:
break
result.append(line)
return "\n".join(result).strip()
def _generate_message_id(from_addr: str) -> str:
domain = from_addr.split("@")[-1] if "@" in from_addr else "meister-eder.local"
return f"<{time.time():.6f}.{id(from_addr)}@{domain}>"
# ---------------------------------------------------------------------------
# Main class
# ---------------------------------------------------------------------------
class EmailChannel:
"""Wraps IMAP polling and SMTP sending for the email conversation channel."""
def __init__(
self,
imap_host: str,
imap_port: int,
smtp_host: str,
smtp_port: int,
username: str,
password: str,
use_ssl: bool = True,
use_tls: bool = True,
registration_email: str = "",
) -> None:
self._imap_host = imap_host
self._imap_port = imap_port
self._smtp_host = smtp_host
self._smtp_port = smtp_port
self._username = username
self._password = password
self._use_ssl = use_ssl
self._use_tls = use_tls
self._from_email = registration_email or username
# ------------------------------------------------------------------
# IMAP — receive
# ------------------------------------------------------------------
def fetch_unread_messages(self) -> list[dict]:
"""Poll the inbox and return all unread messages as structured dicts.
Each dict contains:
from — sender email address
subject — decoded subject line
message_id — Message-ID header of this email
in_reply_to — In-Reply-To header (may be empty)
references — References header (may be empty)
thread_id — canonical ID for the email thread
body — stripped plain-text body (quoted text removed)
"""
messages: list[dict] = []
try:
imap = self._connect_imap()
imap.select("INBOX")
_, data = imap.search(None, "UNSEEN")
msg_nums = data[0].split()
for num in msg_nums:
try:
_, raw_data = imap.fetch(num, "(RFC822)")
raw = raw_data[0][1]
msg = email.message_from_bytes(raw)
from_addr = email.utils.parseaddr(msg.get("From", ""))[1]
subject = _decode_header(msg.get("Subject", "(no subject)"))
message_id = msg.get("Message-ID", "").strip()
in_reply_to = msg.get("In-Reply-To", "").strip()
references = msg.get("References", "").strip()
body = _extract_text(msg)
body = _strip_quoted_text(body)
if not body.strip():
imap.store(num, "+FLAGS", "\\Seen")
continue
thread_id = self._resolve_thread_id(message_id, in_reply_to, references)
messages.append(
{
"from": from_addr,
"subject": subject,
"message_id": message_id,
"in_reply_to": in_reply_to,
"references": references,
"thread_id": thread_id,
"body": body,
}
)
imap.store(num, "+FLAGS", "\\Seen")
except Exception:
logger.exception("Error processing IMAP message %s", num)
imap.logout()
except Exception:
logger.exception("IMAP connection/fetch error")
return messages
# ------------------------------------------------------------------
# SMTP — send
# ------------------------------------------------------------------
def send_reply(
self,
to: str,
subject: str,
body: str,
in_reply_to: str = "",
references: str = "",
) -> str:
"""Send an email reply.
Returns the new Message-ID so the caller can track the thread.
"""
new_message_id = _generate_message_id(self._from_email)
# Ensure subject starts with "Re:"
if not subject.lower().startswith("re:"):
subject = f"Re: {subject}"
# Build References chain
ref_parts = [r for r in [references, in_reply_to] if r]
new_references = " ".join(ref_parts)
msg = MIMEMultipart("alternative")
msg["From"] = self._from_email
msg["To"] = to
msg["Subject"] = subject
msg["Message-ID"] = new_message_id
if in_reply_to:
msg["In-Reply-To"] = in_reply_to
if new_references:
msg["References"] = new_references
msg.attach(MIMEText(body, "plain", "utf-8"))
if not self._smtp_host:
logger.warning("SMTP not configured — reply NOT sent to %s: %s", to, subject)
logger.debug("Reply body:\n%s", body)
return new_message_id
try:
if self._use_tls:
server = smtplib.SMTP(self._smtp_host, self._smtp_port)
server.starttls()
else:
server = smtplib.SMTP_SSL(self._smtp_host, self._smtp_port)
server.login(self._username, self._password)
server.sendmail(self._from_email, [to], msg.as_string())
server.quit()
logger.info("Reply sent to %s (thread %s)", to, in_reply_to or new_message_id)
except Exception:
logger.exception("Failed to send reply to %s", to)
return new_message_id
def send_reminder(
self,
to: str,
subject: str,
body: str,
in_reply_to: str = "",
references: str = "",
) -> None:
"""Send a reminder email for an incomplete registration."""
self.send_reply(
to=to,
subject=subject,
body=body,
in_reply_to=in_reply_to,
references=references,
)
# ------------------------------------------------------------------
# Internal helpers
# ------------------------------------------------------------------
def _connect_imap(self) -> imaplib.IMAP4:
if self._use_ssl:
conn = imaplib.IMAP4_SSL(self._imap_host, self._imap_port)
else:
conn = imaplib.IMAP4(self._imap_host, self._imap_port)
conn.login(self._username, self._password)
return conn
@staticmethod
def _resolve_thread_id(message_id: str, in_reply_to: str, references: str) -> str:
"""Determine the canonical thread ID from email threading headers.
The root of the thread is the first message ever sent — its ID is the
first token in the References header (oldest first convention).
"""
if references:
first_ref = references.strip().split()[0]
return first_ref
if in_reply_to:
return in_reply_to.strip()
return message_id.strip() or f"<unknown-{time.time():.0f}>"