From ae1cbe27a478b1277f3b6407cfce9ef77aca0932 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Thu, 11 Jun 2026 22:50:58 +0200
Subject: [PATCH 1/7] feat: add core modules (config, state, diff, apply,
 health)

---
 apply.py  | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 config.py |  53 ++++++++++++++++++++++++++
 diff.py   |  65 ++++++++++++++++++++++++++++++++
 health.py | 111 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 state.py  | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 442 insertions(+)
 create mode 100644 apply.py
 create mode 100644 config.py
 create mode 100644 diff.py
 create mode 100644 health.py
 create mode 100644 state.py

diff --git a/apply.py b/apply.py
new file mode 100644
index 0000000..294b0cb
--- /dev/null
+++ b/apply.py
@@ -0,0 +1,107 @@
+import logging
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+
+def _extract_uid(ical_data: bytes) -> str:
+    for line in ical_data.decode("utf-8", errors="replace").split("\r\n"):
+        if line.upper().startswith("UID:"):
+            return line[4:].strip()
+    return ""
+
+
+def _find_event_by_uid(calendar: Any, uid: str) -> Any | None:
+    try:
+        for event in calendar.events():
+            content = event.data.decode("utf-8", errors="replace")
+            for line in content.split("\r\n"):
+                if line.upper().startswith("UID:"):
+                    if line[4:].strip() == uid:
+                        return event
+    except Exception as exc:
+        logger.error("Error scanning events for UID %s: %s", uid, exc)
+    return None
+
+
+def _add_event(calendar: Any, uid: str, ical_data: bytes) -> bool:
+    try:
+        calendar.add_event(ical_data)
+        return True
+    except Exception as exc:
+        logger.error("Failed to add event %s: %s", uid, exc)
+        return False
+
+
+def _delete_event(calendar: Any, uid: str) -> bool:
+    try:
+        event = _find_event_by_uid(calendar, uid)
+        if event:
+            event.delete()
+            return True
+        logger.error("Event with UID %s not found", uid)
+        return False
+    except Exception as exc:
+        logger.error("Failed to delete event %s: %s", uid, exc)
+        return False
+
+
+def _update_event(calendar: Any, uid: str, ical_data: bytes) -> bool:
+    if not _delete_event(calendar, uid):
+        return False
+    return _add_event(calendar, uid, ical_data)
+
+
+def apply_adds(calendar: Any, events: dict[str, bytes], max_workers: int = 10) -> tuple[int, int]:
+    success = 0
+    errors = 0
+
+    with ThreadPoolExecutor(max_workers=max_workers) as executor:
+        futures = {
+            executor.submit(_add_event, calendar, uid, data): uid
+            for uid, data in events.items()
+        }
+        for future in as_completed(futures):
+            if future.result():
+                success += 1
+            else:
+                errors += 1
+
+    return success, errors
+
+
+def apply_updates(calendar: Any, events: dict[str, bytes], max_workers: int = 10) -> tuple[int, int]:
+    success = 0
+    errors = 0
+
+    with ThreadPoolExecutor(max_workers=max_workers) as executor:
+        futures = {
+            executor.submit(_update_event, calendar, uid, data): uid
+            for uid, data in events.items()
+        }
+        for future in as_completed(futures):
+            if future.result():
+                success += 1
+            else:
+                errors += 1
+
+    return success, errors
+
+
+def apply_deletes(calendar: Any, uids: list[str], max_workers: int = 10) -> tuple[int, int]:
+    success = 0
+    errors = 0
+
+    with ThreadPoolExecutor(max_workers=max_workers) as executor:
+        futures = {
+            executor.submit(_delete_event, calendar, uid): uid
+            for uid in uids
+        }
+        for future in as_completed(futures):
+            if future.result():
+                success += 1
+            else:
+                errors += 1
+
+    return success, errors
diff --git a/config.py b/config.py
new file mode 100644
index 0000000..8263c05
--- /dev/null
+++ b/config.py
@@ -0,0 +1,53 @@
+import os
+from dataclasses import dataclass
+
+
+HEADERS = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Unraid-Sync/1.0"}
+
+
+@dataclass
+class Config:
+    ics_url: str
+    baikal_url: str
+    baikal_user: str
+    baikal_pass: str
+    sync_frequency: int
+
+
+def validate() -> Config:
+    errors = []
+
+    ics_url = os.environ.get("ICS_URL")
+    if not ics_url:
+        errors.append("ICS_URL is required")
+
+    baikal_url = os.environ.get("BAIKAL_URL")
+    if not baikal_url:
+        errors.append("BAIKAL_URL is required")
+
+    baikal_user = os.environ.get("BAIKAL_USER")
+    if not baikal_user:
+        errors.append("BAIKAL_USER is required")
+
+    baikal_pass = os.environ.get("BAIKAL_PASS")
+    if not baikal_pass:
+        errors.append("BAIKAL_PASS is required")
+
+    sync_freq_raw = os.environ.get("SYNC_FREQUENCY", "5")
+    try:
+        sync_frequency = int(sync_freq_raw)
+        if sync_frequency <= 0:
+            raise ValueError
+    except ValueError:
+        errors.append("SYNC_FREQUENCY must be a positive integer")
+
+    if errors:
+        raise ValueError("\n".join(errors))
+
+    return Config(
+        ics_url=ics_url,
+        baikal_url=baikal_url,
+        baikal_user=baikal_user,
+        baikal_pass=baikal_pass,
+        sync_frequency=sync_frequency,
+    )
diff --git a/diff.py b/diff.py
new file mode 100644
index 0000000..d0d4051
--- /dev/null
+++ b/diff.py
@@ -0,0 +1,65 @@
+import hashlib
+import logging
+from icalendar import Calendar
+
+logger = logging.getLogger(__name__)
+
+
+def parse_ics_events(ics_text: str) -> dict[str, str]:
+    cal = Calendar.from_ical(ics_text.encode() if isinstance(ics_text, str) else ics_text)
+    result = {}
+    for component in cal.walk():
+        if component.name != "VEVENT":
+            continue
+        uid = component.get("UID")
+        if uid is None:
+            logger.warning("Skipping event with no UID")
+            continue
+        uid_str = str(uid)
+        try:
+            event_bytes = component.to_ical()
+            file_hash = hashlib.sha256(event_bytes).hexdigest()
+            result[uid_str] = file_hash
+        except Exception as e:
+            logger.warning("Failed to process event %s: %s", uid_str, e)
+    return result
+
+
+def compute_diff(ics_uids: dict[str, str], known_uids: dict[str, str]) -> dict:
+    to_add = []
+    to_update = []
+    to_delete = []
+
+    for uid, file_hash in ics_uids.items():
+        if uid not in known_uids:
+            to_add.append((uid, file_hash))
+        elif known_uids[uid] != file_hash:
+            to_update.append((uid, file_hash))
+
+    for uid in known_uids:
+        if uid not in ics_uids:
+            to_delete.append(uid)
+
+    return {
+        "to_add": to_add,
+        "to_update": to_update,
+        "to_delete": to_delete,
+    }
+
+
+def parse_ics_events_with_data(ics_text: str) -> dict[str, bytes]:
+    cal = Calendar.from_ical(ics_text.encode() if isinstance(ics_text, str) else ics_text)
+    result = {}
+    for component in cal.walk():
+        if component.name != "VEVENT":
+            continue
+        uid = component.get("UID")
+        if uid is None:
+            logger.warning("Skipping event with no UID")
+            continue
+        uid_str = str(uid)
+        try:
+            result[uid_str] = component.to_ical()
+        except Exception as e:
+            logger.warning("Failed to process event %s: %s", uid_str, e)
+    return result
diff --git a/health.py b/health.py
new file mode 100644
index 0000000..d20cebc
--- /dev/null
+++ b/health.py
@@ -0,0 +1,111 @@
+import json
+import threading
+from datetime import datetime, timezone
+from http.server import HTTPServer, BaseHTTPRequestHandler
+from io import StringIO
+
+
+class HealthServer:
+    def __init__(self, port: int = 8081):
+        self.port = port
+        self.lock = threading.Lock()
+        self.last_sync = None
+        self.last_sync_duration = 0.0
+        self.last_sync_success = None
+        self.event_count = 0
+        self.syncs_total = 0
+        self.syncs_failed = 0
+        self.server = None
+        self.thread = None
+
+    def start(self) -> None:
+        handler = self._make_handler()
+
+        self.server = HTTPServer(("0.0.0.0", self.port), handler)
+        self.thread = threading.Thread(target=self.server.serve_forever, daemon=True)
+        self.thread.start()
+
+    def stop(self) -> None:
+        if self.server:
+            self.server.shutdown()
+            self.server = None
+            self.thread = None
+
+    def update_status(self, last_sync: datetime, duration: float, success: bool, event_count: int) -> None:
+        with self.lock:
+            self.last_sync = last_sync
+            self.last_sync_duration = duration
+            self.last_sync_success = success
+            self.event_count = event_count
+            self.syncs_total += 1
+            if not success:
+                self.syncs_failed += 1
+
+    def _make_handler(self):
+        server_self = self
+
+        class Handler(BaseHTTPRequestHandler):
+            def do_GET(self):
+                if self.path == "/health":
+                    self._handle_health(server_self)
+                elif self.path == "/metrics":
+                    self._handle_metrics(server_self)
+                else:
+                    self.send_response(404)
+                    self.send_header("Content-Type", "application/json")
+                    self.end_headers()
+                    self.wfile.write(json.dumps({"error": "not found"}).encode())
+
+            def _handle_health(self, srv):
+                with srv.lock:
+                    status = "ok"
+                    result = "none"
+
+                    if srv.last_sync_success is not None:
+                        if srv.last_sync_success:
+                            result = "success"
+                        else:
+                            result = "failure"
+                            status = "error"
+
+                    payload = {
+                        "status": status,
+                        "last_sync": srv.last_sync.isoformat() if srv.last_sync else None,
+                        "last_sync_duration_sec": srv.last_sync_duration,
+                        "last_sync_result": result,
+                        "event_count": srv.event_count,
+                        "syncs_total": srv.syncs_total,
+                        "syncs_failed": srv.syncs_failed,
+                    }
+
+                body = json.dumps(payload).encode()
+                self.send_response(200)
+                self.send_header("Content-Type", "application/json")
+                self.end_headers()
+                self.wfile.write(body)
+
+            def _handle_metrics(self, srv):
+                with srv.lock:
+                    last_success = 1 if srv.last_sync_success else 0
+                    duration = srv.last_sync_duration
+                    evt_count = srv.event_count
+                    total = srv.syncs_total
+                    failed = srv.syncs_failed
+
+                buf = StringIO()
+                buf.write(f"baikal_sync_last_duration_seconds {duration}\n")
+                buf.write(f"baikal_sync_events_total {evt_count}\n")
+                buf.write(f"baikal_sync_total {total}\n")
+                buf.write(f"baikal_sync_failures_total {failed}\n")
+                buf.write(f"baikal_sync_last_success {last_success}\n")
+
+                body = buf.getvalue().encode()
+                self.send_response(200)
+                self.send_header("Content-Type", "text/plain; version=0.0.4; charset=utf-8")
+                self.end_headers()
+                self.wfile.write(body)
+
+            def log_message(self, format, *args):
+                pass
+
+        return Handler
diff --git a/state.py b/state.py
new file mode 100644
index 0000000..5f70e2a
--- /dev/null
+++ b/state.py
@@ -0,0 +1,106 @@
+import sqlite3
+import threading
+from datetime import datetime, timezone
+
+
+class SyncState:
+    def __init__(self, db_path="./sync.db"):
+        self.db_path = db_path
+        self._lock = threading.Lock()
+        self._conn = sqlite3.connect(db_path, timeout=30)
+        self._conn.execute("PRAGMA journal_mode=WAL")
+        self._conn.execute("""
+            CREATE TABLE IF NOT EXISTS events (
+                uid TEXT PRIMARY KEY,
+                content_hash TEXT NOT NULL,
+                synced_at TIMESTAMP NOT NULL
+            )
+        """)
+        self._conn.execute("""
+            CREATE TABLE IF NOT EXISTS ics_cache (
+                id INTEGER PRIMARY KEY CHECK(id=1),
+                ics_hash TEXT,
+                etag TEXT,
+                fetched_at TIMESTAMP
+            )
+        """)
+        self._conn.commit()
+        return self
+
+    def get_event_uids(self) -> set[str]:
+        with self._lock:
+            cur = self._conn.execute("SELECT uid FROM events")
+            return {row[0] for row in cur.fetchall()}
+
+    def get_event_hash(self, uid: str) -> str | None:
+        with self._lock:
+            cur = self._conn.execute("SELECT content_hash FROM events WHERE uid = ?", (uid,))
+            row = cur.fetchone()
+            return row[0] if row else None
+
+    def upsert_event(self, uid: str, content_hash: str) -> None:
+        with self._lock:
+            self._conn.execute("""
+                INSERT OR REPLACE INTO events (uid, content_hash, synced_at)
+                VALUES (?, ?, ?)
+            """, (uid, content_hash, datetime.now(timezone.utc).isoformat()))
+            self._conn.commit()
+
+    def delete_event(self, uid: str) -> None:
+        with self._lock:
+            self._conn.execute("DELETE FROM events WHERE uid = ?", (uid,))
+            self._conn.commit()
+
+    def clear_events(self) -> int:
+        with self._lock:
+            cur = self._conn.execute("SELECT COUNT(*) FROM events")
+            count = cur.fetchone()[0]
+            self._conn.execute("DELETE FROM events")
+            self._conn.commit()
+            return count
+
+    def get_ics_cache(self) -> tuple[str | None, str | None, str | None]:
+        with self._lock:
+            cur = self._conn.execute("SELECT ics_hash, etag, fetched_at FROM ics_cache WHERE id = 1")
+            row = cur.fetchone()
+            if row:
+                return (row[0], row[1], row[2])
+            return (None, None, None)
+
+    def set_ics_cache(self, ics_hash: str, etag: str | None) -> None:
+        with self._lock:
+            self._conn.execute("""
+                INSERT INTO ics_cache (id, ics_hash, etag, fetched_at)
+                VALUES (1, ?, ?, ?)
+                ON CONFLICT(id) DO UPDATE SET ics_hash = ?, etag = ?, fetched_at = ?
+            """, (ics_hash, etag, datetime.now(timezone.utc).isoformat(),
+                   ics_hash, etag, datetime.now(timezone.utc).isoformat()))
+            self._conn.commit()
+
+    def clear_ics_cache(self) -> None:
+        with self._lock:
+            self._conn.execute("DELETE FROM ics_cache")
+            self._conn.commit()
+
+    def snapshot(self) -> dict:
+        with self._lock:
+            cur = self._conn.execute("SELECT uid, content_hash FROM events")
+            rows = cur.fetchall()
+            return {
+                "uids": [r[0] for r in rows],
+                "hashes": {r[0]: r[1] for r in rows}
+            }
+
+    def restore_snapshot(self, data: dict) -> None:
+        with self._lock:
+            self._conn.execute("DELETE FROM events")
+            for uid, content_hash in data.get("hashes", {}).items():
+                self._conn.execute("""
+                    INSERT INTO events (uid, content_hash, synced_at)
+                    VALUES (?, ?, ?)
+                """, (uid, content_hash, datetime.now(timezone.utc).isoformat()))
+            self._conn.commit()
+
+    def close(self) -> None:
+        with self._lock:
+            self._conn.close()

From 64d078f45793bd896cb7592c13f3ed3634372568 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Thu, 11 Jun 2026 22:54:36 +0200
Subject: [PATCH 2/7] feat: rewrite sync orchestrator with incremental delta
 sync

---
 sync_calendar.py | 366 +++++++++++++++++++++++++++--------------------
 1 file changed, 212 insertions(+), 154 deletions(-)

diff --git a/sync_calendar.py b/sync_calendar.py
index 67807bb..b8c6e94 100644
--- a/sync_calendar.py
+++ b/sync_calendar.py
@@ -1,182 +1,240 @@
+import os
+import signal
+import time
+import hashlib
+import logging
+import threading
 import requests
 import caldav
-from caldav.elements import dav, cdav
-from datetime import datetime
-import os
-import time
-import concurrent.futures
+from datetime import datetime, timezone
 
-# --- CONFIGURACIÓN ---
-# Default to 5 minutes
-SYNC_FREQUENCY_MINUTES = int(os.getenv("SYNC_FREQUENCY", 5))
-SYNC_FREQUENCY_SECONDS = SYNC_FREQUENCY_MINUTES * 60
+from config import validate, HEADERS, Config
+from state import SyncState
+from diff import parse_ics_events, compute_diff, parse_ics_events_with_data
+from apply import apply_adds, apply_updates, apply_deletes
+from health import HealthServer
 
-# Tu URL de Outlook
-ICS_URL = os.getenv("ICS_URL")
-
-# Tu Baïkal
-BAIKAL_URL = os.getenv("BAIKAL_URL")
-BAIKAL_USER = os.getenv("BAIKAL_USER")
-BAIKAL_PASS = os.getenv("BAIKAL_PASS")
-CALENDAR_ID = os.getenv("CALENDAR_ID")
-
-# Headers para parecer un navegador real y evitar 'Connection Reset'
-HEADERS = {
-    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Unraid-Sync/1.0"
-}
+logger = logging.getLogger(__name__)
+shutdown_event = threading.Event()
 
 
-def normalize_url(url):
-    """Normalize URLs to make matching robust against trailing slash differences."""
-    return str(url).strip().rstrip("/")
+def setup_logging():
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s [%(levelname)s] %(message)s",
+        datefmt="%Y-%m-%d %H:%M:%S",
+    )
 
 
-def find_calendar_by_url(calendars, target_url):
-    """Find a calendar whose URL matches the configured Baikal calendar URL."""
-    normalized_target = normalize_url(target_url)
+def find_calendar(client, config):
+    principal = client.principal()
+    calendars = principal.calendars()
+    calendar_id = os.environ.get("CALENDAR_ID")
+
+    if calendar_id:
+        for cal in calendars:
+            if calendar_id in str(cal.url):
+                return cal
+        logger.error("Calendar with ID '%s' not found", calendar_id)
+        for c in calendars:
+            logger.error("  Available: %s", c.url)
+        return None
+
+    target = config.baikal_url.rstrip("/")
     for cal in calendars:
-        if normalize_url(cal.url) == normalized_target:
+        if target in str(cal.url) or str(cal.url).rstrip("/") == target:
             return cal
+
+    if calendars:
+        return calendars[0]
+
     return None
 
-def delete_event(event):
-    """Helper function to delete a single event."""
+
+def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
+    start_time = time.time()
+    logger.info("Starting sync cycle...")
+
     try:
-        event.delete()
-        return True
-    except Exception as e:
-        print(f"!!! Error deleting event {event}: {e}")
+        r = requests.head(config.ics_url, headers=HEADERS, timeout=30, allow_redirects=True)
+        r.raise_for_status()
+        remote_etag = r.headers.get("ETag")
+        cached_hash, cached_etag, _ = state.get_ics_cache()
+
+        if remote_etag and cached_etag == remote_etag:
+            logger.info("No changes detected (ETag match). Skipping sync.")
+            return True
+
+        response = requests.get(config.ics_url, headers=HEADERS, timeout=30)
+        response.raise_for_status()
+        ics_text = response.text
+        ics_hash = hashlib.sha256(ics_text.encode("utf-8")).hexdigest()
+
+        if cached_hash == ics_hash:
+            logger.info("No changes detected (hash match). Skipping sync.")
+            if remote_etag:
+                state.set_ics_cache(ics_hash, remote_etag)
+            return True
+
+        state.set_ics_cache(ics_hash, remote_etag)
+        logger.info("ICS changed. Downloaded %d bytes, hash %s", len(ics_text), ics_hash[:12])
+
+        ics_uids = parse_ics_events(ics_text)
+        known_uids = {}
+        for uid in state.get_event_uids():
+            h = state.get_event_hash(uid)
+            if h:
+                known_uids[uid] = h
+
+        deltas = compute_diff(ics_uids, known_uids)
+        to_add = deltas["to_add"]
+        to_update = deltas["to_update"]
+        to_delete = deltas["to_delete"]
+
+        if not to_add and not to_update and not to_delete:
+            logger.info("Calendar is already in sync.")
+            duration = time.time() - start_time
+            health.update_status(
+                datetime.now(timezone.utc),
+                duration,
+                True,
+                len(ics_uids),
+            )
+            return True
+
+        logger.info(
+            "Delta: %d to add, %d to update, %d to delete",
+            len(to_add),
+            len(to_update),
+            len(to_delete),
+        )
+
+        client = caldav.DAVClient(
+            url=config.baikal_url,
+            username=config.baikal_user,
+            password=config.baikal_pass,
+            headers=HEADERS,
+            ssl_verify_cert=True,
+        )
+        calendar = find_calendar(client, config)
+        if not calendar:
+            logger.error("Failed to find calendar")
+            duration = time.time() - start_time
+            health.update_status(
+                datetime.now(timezone.utc),
+                duration,
+                False,
+                0,
+            )
+            return False
+
+        snapshot = state.snapshot()
+        events_data = parse_ics_events_with_data(ics_text)
+
+        add_events = {uid: events_data[uid] for uid, _ in to_add if uid in events_data}
+        update_events = {uid: events_data[uid] for uid, _ in to_update if uid in events_data}
+        delete_uids = to_delete
+
+        try:
+            logger.info("Phase 1: Adding %d events...", len(add_events))
+            if add_events:
+                s, e = apply_adds(calendar, add_events)
+                logger.info("Added %d/%d events (%d errors)", s, len(add_events), e)
+
+            logger.info("Phase 2: Updating %d events...", len(update_events))
+            if update_events:
+                s, e = apply_updates(calendar, update_events)
+                logger.info("Updated %d/%d events (%d errors)", s, len(update_events), e)
+
+            logger.info("Phase 3: Deleting %d events...", len(delete_uids))
+            if delete_uids:
+                s, e = apply_deletes(calendar, delete_uids)
+                logger.info("Deleted %d/%d events (%d errors)", s, len(delete_uids), e)
+
+            for uid, h in ics_uids.items():
+                state.upsert_event(uid, h)
+
+            for uid in delete_uids:
+                state.delete_event(uid)
+
+            total = len(ics_uids)
+            duration = time.time() - start_time
+            logger.info("Sync completed in %.1fs. Total events: %d", duration, total)
+            health.update_status(
+                datetime.now(timezone.utc),
+                duration,
+                True,
+                total,
+            )
+            return True
+
+        except Exception as exc:
+            logger.error("Sync failed: %s. Rolling back state.", exc)
+            state.restore_snapshot(snapshot)
+            duration = time.time() - start_time
+            health.update_status(
+                datetime.now(timezone.utc),
+                duration,
+                False,
+                0,
+            )
+            return False
+
+    except Exception as exc:
+        logger.error("Sync error: %s", exc)
+        duration = time.time() - start_time
+        health.update_status(
+            datetime.now(timezone.utc),
+            duration,
+            False,
+            0,
+        )
         return False
 
-def delete_all_events(calendar):
-    """
-    Deletes all events in the calendar as fast as possible using threads.
-    """
-    print("-> Buscando eventos para borrar...")
+
+def main():
+    setup_logging()
+    logger.info("Starting Baikal Sync service...")
+
     try:
-        events = calendar.events()
-    except Exception as e:
-        print(f"!!! Error al obtener eventos: {e}")
-        return
+        config = validate()
+    except ValueError as exc:
+        logger.error("Configuration error: %s", exc)
+        raise SystemExit(1)
 
-    total_events = len(events)
-    if total_events == 0:
-        print("-> El calendario ya está vacío.")
-        return
+    logger.info("Sync frequency: %d minutes", config.sync_frequency)
+    state = SyncState("./sync.db")
+    health = HealthServer(8081)
+    health.start()
+    logger.info("Health endpoint on :8081")
 
-    print(f"-> Borrando {total_events} eventos rápidamente...")
-    
-    # Usamos ThreadPoolExecutor para borrar en paralelo
-    deleted_count = 0
-    with concurrent.futures.ThreadPoolExecutor(max_workers=10) as executor:
-        results = list(executor.map(delete_event, events))
-        deleted_count = results.count(True)
+    backoff = 0
 
-    print(f"-> Limpieza completada. Borrados {deleted_count}/{total_events} eventos.")
+    def handle_signal(signum, frame):
+        logger.info("Received signal %s. Shutting down...", signum)
+        shutdown_event.set()
 
-def sync():
-    if not all([ICS_URL, BAIKAL_URL, BAIKAL_USER, BAIKAL_PASS]):
-        print(f"[{datetime.now()}] !!! Error: Faltan variables de entorno. Asegúrate de configurar ICS_URL, BAIKAL_URL, BAIKAL_USER y BAIKAL_PASS.")
-        return
+    signal.signal(signal.SIGTERM, handle_signal)
+    signal.signal(signal.SIGINT, handle_signal)
 
-    print(f"[{datetime.now()}] Iniciando sincronización...")
-    
-    # 1. Descargar ICS de Outlook
-    print("-> Descargando calendario de Outlook...")
-    try:
-        response = requests.get(ICS_URL, headers=HEADERS, timeout=30)
-        response.raise_for_status()
-        ics_data = response.text
-        print(f"-> Descarga exitosa ({len(ics_data)} bytes).")
-    except Exception as e:
-        print(f"!!! Error descargando Outlook: {e}")
-        return
+    while not shutdown_event.is_set():
+        success = sync_once(state, health, config)
 
-    # 2. Conectar a Baïkal
-    print("-> Conectando a Baïkal...")
-    try:
-        client = caldav.DAVClient(
-            url=BAIKAL_URL,
-            username=BAIKAL_USER,
-            password=BAIKAL_PASS,
-            headers=HEADERS,  # Clave para evitar el bloqueo
-            ssl_verify_cert=True # Cambiar a False si tienes problemas de certificado SSL auto-firmado
-        )
-        principal = client.principal()
-        calendars = principal.calendars()
-        
-        # Buscar el calendario correcto por ID si se proporciona
-        calendar = None
-        if CALENDAR_ID:
-            print(f"-> Buscando calendario con ID: {CALENDAR_ID}")
-            for cal in calendars:
-                # Comprobamos si el ID está en la URL del calendario
-                if CALENDAR_ID in str(cal.url):
-                    calendar = cal
-                    break
-            
-            if not calendar:
-                print(f"!!! Error: No se encontró ningún calendario con el ID '{CALENDAR_ID}'. Calendarios disponibles:")
-                for c in calendars:
-                    print(f"   - {c.url}")
-                return
+        if success:
+            backoff = 0
+            sleep_time = config.sync_frequency * 60
         else:
-            # Si no hay CALENDAR_ID, seleccionar por BAIKAL_URL
-            if not calendars:
-                print("!!! No se encontró ningún calendario en esa URL.")
-                return
+            backoff = max(1, min(backoff * 2 if backoff > 0 else 1, 30))
+            sleep_time = backoff * 60
+            logger.info("Sync failed. Backing off %d minutes...", backoff)
 
-            calendar = find_calendar_by_url(calendars, BAIKAL_URL)
-            if not calendar:
-                print("!!! Error: No se encontró un calendario que coincida con BAIKAL_URL.")
-                print(f"   BAIKAL_URL configurado: {BAIKAL_URL}")
-                print("   Calendarios disponibles:")
-                for c in calendars:
-                    print(f"   - {c.url}")
-                return
+        logger.info("Next sync in %d seconds...", sleep_time)
+        shutdown_event.wait(sleep_time)
 
-        print(f"-> Calendario seleccionado: {calendar}")
-        print(f"-> URL del calendario seleccionado: {calendar.url}")
+    state.close()
+    health.stop()
+    logger.info("Shutdown complete.")
 
-        # 3. Borrar eventos antiguos (NUEVO)
-        delete_all_events(calendar)
-
-        # 4. Importar eventos
-        print("-> Procesando archivo ICS...")
-        from icalendar import Calendar
-        cal = Calendar.from_ical(ics_data)
-        
-        events = cal.walk('vevent')
-        total_events = len(events)
-        print(f"-> Encontrados {total_events} eventos para importar.")
-        
-        success_count = 0
-        error_count = 0
-        
-        for i, component in enumerate(events, 1):
-            try:
-                # Intentamos pasar el string decodificado
-                calendar.add_event(component.to_ical().decode('utf-8'))
-                success_count += 1
-            except Exception as ev_err:
-                error_count += 1
-                # Solo imprimimos los primeros 5 errores para no saturar
-                if error_count <= 5:
-                    summary = component.get('summary', 'sin titulo')
-                    print(f"!!! Error ({i}/{total_events}) '{summary}': {ev_err}")
-            
-            # Print progress every 50 events
-            if i % 50 == 0:
-                print(f"   Procesados {i}/{total_events} (Exitos: {success_count}, Errores: {error_count})")
-                
-        print(f"-> ¡Sincronización finalizada! Éxitos: {success_count}, Errores: {error_count}")
-
-    except Exception as e:
-        print(f"!!! Error en Baïkal: {e}")
 
 if __name__ == "__main__":
-    print(f"Iniciando servicio de sincronización. Frecuencia: {SYNC_FREQUENCY_MINUTES} minutos ({SYNC_FREQUENCY_SECONDS} segundos).")
-    while True:
-        sync()
-        print(f"[{datetime.now()}] Durmiendo {SYNC_FREQUENCY_MINUTES} minutos...")
-        time.sleep(SYNC_FREQUENCY_SECONDS)
+    main()

From 0f390ff1e191ef39d2c045a05934164f4d9bdae7 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Thu, 11 Jun 2026 23:00:34 +0200
Subject: [PATCH 3/7] feat: add tests, update configs, fix state.py return,
 update gitignore

---
 .env.example         |  6 ++++
 .gitignore           | 10 ++++++
 Dockerfile           |  7 +++--
 docker-compose.yml   | 12 +++++---
 main.py              |  4 +--
 pyproject.toml       | 12 ++++++--
 requirements.txt     |  7 +++--
 state.py             |  1 -
 tests/conftest.py    | 68 +++++++++++++++++++++++++++++++++++++++++
 tests/test_config.py | 49 +++++++++++++++++++++++++++++
 tests/test_diff.py   | 73 ++++++++++++++++++++++++++++++++++++++++++++
 tests/test_state.py  | 71 ++++++++++++++++++++++++++++++++++++++++++
 12 files changed, 305 insertions(+), 15 deletions(-)
 create mode 100644 .env.example
 create mode 100644 tests/conftest.py
 create mode 100644 tests/test_config.py
 create mode 100644 tests/test_diff.py
 create mode 100644 tests/test_state.py

diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..c97309c
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,6 @@
+ICS_URL=https://outlook.office365.com/owa/calendar/your-calendar.ics
+BAIKAL_URL=https://your-baikal.com/dav.php/calendars/USER/calendar-id/
+BAIKAL_USER=your-username
+BAIKAL_PASS=your-password
+SYNC_FREQUENCY=5
+CALENDAR_ID=
diff --git a/.gitignore b/.gitignore
index 110b0a6..3891c11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,13 @@ wheels/
 # Virtual environments
 .venv
 .env
+
+# Sync state database
+*.db
+
+# Playwright MCP artifacts
+.playwright-mcp/
+*.png
+
+# Test artifacts
+.pytest_cache/
diff --git a/Dockerfile b/Dockerfile
index 12f6bc2..db4d074 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,6 +7,9 @@ WORKDIR /app
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
-COPY sync_calendar.py .
+COPY . .
 
-CMD ["python", "-u", "sync_calendar.py"]
+HEALTHCHECK --interval=60s --timeout=10s --start-period=5s --retries=3 \
+    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8081/health')" || exit 1
+
+CMD ["python", "-u", "main.py"]
diff --git a/docker-compose.yml b/docker-compose.yml
index 60e3517..659d65a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -8,7 +8,11 @@ services:
       - BAIKAL_URL=${BAIKAL_URL}
       - BAIKAL_USER=${BAIKAL_USER}
       - BAIKAL_PASS=${BAIKAL_PASS}
-      - SYNC_FREQUENCY=5 # Minutes
-    # If your Baikal is on the same host, you might need network_mode: "host" 
-    # or ensure they share a network.
-    # network_mode: "host" 
+      - SYNC_FREQUENCY=${SYNC_FREQUENCY:-5}
+      - CALENDAR_ID=${CALENDAR_ID:-}
+    healthcheck:
+      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:8081/health')"]
+      interval: 60s
+      timeout: 10s
+      retries: 3
+      start_period: 5s
diff --git a/main.py b/main.py
index 9d3c4bd..23f4e99 100644
--- a/main.py
+++ b/main.py
@@ -1,6 +1,4 @@
-def main():
-    print("Hello from ics-to-caldav!")
-
+from sync_calendar import main
 
 if __name__ == "__main__":
     main()
diff --git a/pyproject.toml b/pyproject.toml
index 4220eb6..81c71b0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [project]
 name = "ics-to-caldav"
-version = "0.1.0"
-description = "Add your description here"
+version = "1.0.0"
+description = "Incremental CalDAV sync from Outlook ICS to Baikal"
 readme = "README.md"
 requires-python = ">=3.13"
 dependencies = [
@@ -9,3 +9,11 @@ dependencies = [
     "icalendar>=6.3.2",
     "requests>=2.32.5",
 ]
+
+[project.optional-dependencies]
+test = [
+    "pytest>=8.0",
+]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
diff --git a/requirements.txt b/requirements.txt
index eeb459b..9536ef1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
-caldav>=1.0.0
-icalendar>=5.0.0
-requests>=2.20.0
+caldav>=2.2.3
+icalendar>=6.3.2
+requests>=2.32.5
+pytest>=8.0
diff --git a/state.py b/state.py
index 5f70e2a..d9954ae 100644
--- a/state.py
+++ b/state.py
@@ -25,7 +25,6 @@ class SyncState:
             )
         """)
         self._conn.commit()
-        return self
 
     def get_event_uids(self) -> set[str]:
         with self._lock:
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..b20f0a4
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,68 @@
+import os
+import sys
+import pytest
+import tempfile
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
+
+@pytest.fixture
+def ics_sample():
+    """Return a sample ICS string with 2 events."""
+    return """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test
+BEGIN:VEVENT
+UID:evt-001@test.com
+DTSTAMP:20240101T000000Z
+DTSTART:20240101T100000Z
+DTEND:20240101T110000Z
+SUMMARY:Event One
+END:VEVENT
+BEGIN:VEVENT
+UID:evt-002@test.com
+DTSTAMP:20240101T000000Z
+DTSTART:20240102T100000Z
+DTEND:20240102T110000Z
+SUMMARY:Event Two
+END:VEVENT
+END:VCALENDAR"""
+
+@pytest.fixture
+def ics_sample_modified():
+    """Return ICS with one modified event and one new event."""
+    return """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test
+BEGIN:VEVENT
+UID:evt-001@test.com
+DTSTAMP:20240101T000000Z
+DTSTART:20240101T100000Z
+DTEND:20240101T120000Z
+SUMMARY:Event One Modified
+END:VEVENT
+BEGIN:VEVENT
+UID:evt-003@test.com
+DTSTAMP:20240101T000000Z
+DTSTART:20240103T100000Z
+DTEND:20240103T110000Z
+SUMMARY:Event Three
+END:VEVENT
+END:VCALENDAR"""
+
+@pytest.fixture
+def tmp_db():
+    """Return a temp database path."""
+    with tempfile.NamedTemporaryFile(suffix=".db", delete=False) as f:
+        path = f.name
+    yield path
+    if os.path.exists(path):
+        os.unlink(path)
+
+@pytest.fixture(autouse=True)
+def env_vars(monkeypatch):
+    """Set up required env vars for config tests."""
+    monkeypatch.setenv("ICS_URL", "https://example.com/cal.ics")
+    monkeypatch.setenv("BAIKAL_URL", "https://baikal.com/dav.php/calendars/user/cal/")
+    monkeypatch.setenv("BAIKAL_USER", "user")
+    monkeypatch.setenv("BAIKAL_PASS", "pass")
+    monkeypatch.setenv("SYNC_FREQUENCY", "5")
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..bb315aa
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,49 @@
+import os
+import pytest
+from config import validate, HEADERS, Config
+
+class TestValidate:
+    def test_valid_config(self, env_vars):
+        cfg = validate()
+        assert isinstance(cfg, Config)
+        assert cfg.ics_url == "https://example.com/cal.ics"
+        assert cfg.baikal_url == "https://baikal.com/dav.php/calendars/user/cal/"
+        assert cfg.baikal_user == "user"
+        assert cfg.baikal_pass == "pass"
+        assert cfg.sync_frequency == 5
+
+    def test_default_frequency(self, monkeypatch, env_vars):
+        monkeypatch.delenv("SYNC_FREQUENCY", raising=False)
+        cfg = validate()
+        assert cfg.sync_frequency == 5
+
+    def test_missing_ics_url(self, monkeypatch, env_vars):
+        monkeypatch.delenv("ICS_URL", raising=False)
+        with pytest.raises(ValueError, match="ICS_URL"):
+            validate()
+
+    def test_missing_all_required(self, monkeypatch, env_vars):
+        for var in ["ICS_URL", "BAIKAL_URL", "BAIKAL_USER", "BAIKAL_PASS"]:
+            monkeypatch.delenv(var, raising=False)
+        with pytest.raises(ValueError):
+            validate()
+
+    def test_invalid_frequency(self, monkeypatch, env_vars):
+        monkeypatch.setenv("SYNC_FREQUENCY", "-1")
+        with pytest.raises(ValueError, match="SYNC_FREQUENCY"):
+            validate()
+
+    def test_frequency_zero(self, monkeypatch, env_vars):
+        monkeypatch.setenv("SYNC_FREQUENCY", "0")
+        with pytest.raises(ValueError, match="SYNC_FREQUENCY"):
+            validate()
+
+    def test_frequency_string(self, monkeypatch, env_vars):
+        monkeypatch.setenv("SYNC_FREQUENCY", "abc")
+        with pytest.raises(ValueError, match="SYNC_FREQUENCY"):
+            validate()
+
+class TestHeaders:
+    def test_headers_exist(self):
+        assert "User-Agent" in HEADERS
+        assert "Unraid-Sync" in HEADERS["User-Agent"]
diff --git a/tests/test_diff.py b/tests/test_diff.py
new file mode 100644
index 0000000..913a6e2
--- /dev/null
+++ b/tests/test_diff.py
@@ -0,0 +1,73 @@
+from diff import parse_ics_events, compute_diff, parse_ics_events_with_data
+
+class TestParseIcsEvents:
+    def test_parse_basic(self, ics_sample):
+        result = parse_ics_events(ics_sample)
+        assert "evt-001@test.com" in result
+        assert "evt-002@test.com" in result
+        assert len(result) == 2
+
+    def test_parse_no_uid(self):
+        ics = """BEGIN:VCALENDAR
+VERSION:2.0
+BEGIN:VEVENT
+DTSTAMP:20240101T000000Z
+DTSTART:20240101T100000Z
+SUMMARY:No UID
+END:VEVENT
+END:VCALENDAR"""
+        result = parse_ics_events(ics)
+        assert len(result) == 0
+
+    def test_hashes_are_sha256(self, ics_sample):
+        result = parse_ics_events(ics_sample)
+        for uid, h in result.items():
+            assert len(h) == 64
+            int(h, 16)
+
+    def test_same_event_same_hash(self, ics_sample):
+        r1 = parse_ics_events(ics_sample)
+        r2 = parse_ics_events(ics_sample)
+        for uid in r1:
+            assert r1[uid] == r2[uid]
+
+    def test_modified_event_different_hash(self, ics_sample, ics_sample_modified):
+        r1 = parse_ics_events(ics_sample)
+        r2 = parse_ics_events(ics_sample_modified)
+        assert r1["evt-001@test.com"] != r2["evt-001@test.com"]
+
+class TestComputeDiff:
+    def test_no_changes(self, ics_sample):
+        ics_uids = parse_ics_events(ics_sample)
+        deltas = compute_diff(ics_uids, ics_uids)
+        assert len(deltas["to_add"]) == 0
+        assert len(deltas["to_update"]) == 0
+        assert len(deltas["to_delete"]) == 0
+
+    def test_add_events(self, ics_sample, ics_sample_modified):
+        original = parse_ics_events(ics_sample)
+        modified = parse_ics_events(ics_sample_modified)
+        deltas = compute_diff(modified, original)
+        assert ("evt-003@test.com", modified["evt-003@test.com"]) in deltas["to_add"]
+
+    def test_delete_events(self, ics_sample, ics_sample_modified):
+        original = parse_ics_events(ics_sample)
+        modified = parse_ics_events(ics_sample_modified)
+        deltas = compute_diff(modified, original)
+        assert "evt-002@test.com" in deltas["to_delete"]
+
+    def test_update_events(self, ics_sample, ics_sample_modified):
+        original = parse_ics_events(ics_sample)
+        modified = parse_ics_events(ics_sample_modified)
+        deltas = compute_diff(modified, original)
+        uid, new_hash = deltas["to_update"][0]
+        assert uid == "evt-001@test.com"
+        assert new_hash == modified["evt-001@test.com"]
+
+class TestParseIcsEventsWithData:
+    def test_returns_bytes(self, ics_sample):
+        result = parse_ics_events_with_data(ics_sample)
+        assert len(result) == 2
+        for uid, data in result.items():
+            assert isinstance(data, bytes)
+            assert b"VEVENT" in data
diff --git a/tests/test_state.py b/tests/test_state.py
new file mode 100644
index 0000000..4cf0bf5
--- /dev/null
+++ b/tests/test_state.py
@@ -0,0 +1,71 @@
+from state import SyncState
+
+class TestSyncState:
+    def test_create_tables(self, tmp_db):
+        state = SyncState(tmp_db)
+        assert True
+        state.close()
+
+    def test_upsert_and_get(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.upsert_event("uid-1", "hash-abc")
+        assert state.get_event_hash("uid-1") == "hash-abc"
+        state.close()
+
+    def test_get_uids(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.upsert_event("uid-1", "h1")
+        state.upsert_event("uid-2", "h2")
+        uids = state.get_event_uids()
+        assert "uid-1" in uids
+        assert "uid-2" in uids
+        assert len(uids) == 2
+        state.close()
+
+    def test_delete_event(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.upsert_event("uid-1", "h1")
+        state.delete_event("uid-1")
+        assert state.get_event_hash("uid-1") is None
+        state.close()
+
+    def test_clear_events(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.upsert_event("uid-1", "h1")
+        state.upsert_event("uid-2", "h2")
+        count = state.clear_events()
+        assert count == 2
+        assert len(state.get_event_uids()) == 0
+        state.close()
+
+    def test_ics_cache(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.set_ics_cache("hash-xyz", "etag-123")
+        h, e, _ = state.get_ics_cache()
+        assert h == "hash-xyz"
+        assert e == "etag-123"
+        state.clear_ics_cache()
+        h, e, _ = state.get_ics_cache()
+        assert h is None
+        assert e is None
+        state.close()
+
+    def test_snapshot_and_restore(self, tmp_db):
+        state = SyncState(tmp_db)
+        state.upsert_event("uid-1", "h1")
+        state.upsert_event("uid-2", "h2")
+        snap = state.snapshot()
+        assert "uid-1" in snap["uids"]
+        state.clear_events()
+        assert len(state.get_event_uids()) == 0
+        state.restore_snapshot(snap)
+        assert len(state.get_event_uids()) == 2
+        assert state.get_event_hash("uid-1") == "h1"
+        state.close()
+
+    def test_empty_state(self, tmp_db):
+        state = SyncState(tmp_db)
+        assert len(state.get_event_uids()) == 0
+        h, e, _ = state.get_ics_cache()
+        assert h is None
+        state.close()

From d628f03a827f377477d4b04f82a686365711a96c Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Thu, 11 Jun 2026 23:06:47 +0200
Subject: [PATCH 4/7] fix: stable event hashing, HEAD fallback, caldav
 str/bytes compat

---
 apply.py         | 13 ++++++++++---
 diff.py          | 17 ++++++++++++++---
 sync_calendar.py | 31 ++++++++++++++++++++++++++++---
 3 files changed, 52 insertions(+), 9 deletions(-)

diff --git a/apply.py b/apply.py
index 294b0cb..8cab090 100644
--- a/apply.py
+++ b/apply.py
@@ -5,8 +5,11 @@ from typing import Any
 logger = logging.getLogger(__name__)
 
 
-def _extract_uid(ical_data: bytes) -> str:
-    for line in ical_data.decode("utf-8", errors="replace").split("\r\n"):
+def _extract_uid(ical_data) -> str:
+    raw = ical_data
+    if isinstance(raw, bytes):
+        raw = raw.decode("utf-8", errors="replace")
+    for line in str(raw).split("\r\n"):
         if line.upper().startswith("UID:"):
             return line[4:].strip()
     return ""
@@ -15,7 +18,11 @@ def _extract_uid(ical_data: bytes) -> str:
 def _find_event_by_uid(calendar: Any, uid: str) -> Any | None:
     try:
         for event in calendar.events():
-            content = event.data.decode("utf-8", errors="replace")
+            raw = event.data
+            if isinstance(raw, bytes):
+                content = raw.decode("utf-8", errors="replace")
+            else:
+                content = str(raw)
             for line in content.split("\r\n"):
                 if line.upper().startswith("UID:"):
                     if line[4:].strip() == uid:
diff --git a/diff.py b/diff.py
index d0d4051..7f18706 100644
--- a/diff.py
+++ b/diff.py
@@ -5,6 +5,19 @@ from icalendar import Calendar
 logger = logging.getLogger(__name__)
 
 
+def _stable_event_key(component) -> str:
+    event_bytes = component.to_ical()
+    text = event_bytes.decode("utf-8", errors="replace")
+    stable_lines = []
+    for line in text.split("\r\n"):
+        key = line.split(":")[0].upper() if ":" in line else ""
+        if key in ("DTSTAMP", "LAST-MODIFIED"):
+            continue
+        stable_lines.append(line)
+    stable_text = "\r\n".join(stable_lines)
+    return hashlib.sha256(stable_text.encode("utf-8")).hexdigest()
+
+
 def parse_ics_events(ics_text: str) -> dict[str, str]:
     cal = Calendar.from_ical(ics_text.encode() if isinstance(ics_text, str) else ics_text)
     result = {}
@@ -17,9 +30,7 @@ def parse_ics_events(ics_text: str) -> dict[str, str]:
             continue
         uid_str = str(uid)
         try:
-            event_bytes = component.to_ical()
-            file_hash = hashlib.sha256(event_bytes).hexdigest()
-            result[uid_str] = file_hash
+            result[uid_str] = _stable_event_key(component)
         except Exception as e:
             logger.warning("Failed to process event %s: %s", uid_str, e)
     return result
diff --git a/sync_calendar.py b/sync_calendar.py
index b8c6e94..b265ab0 100644
--- a/sync_calendar.py
+++ b/sync_calendar.py
@@ -56,9 +56,14 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
     logger.info("Starting sync cycle...")
 
     try:
-        r = requests.head(config.ics_url, headers=HEADERS, timeout=30, allow_redirects=True)
-        r.raise_for_status()
-        remote_etag = r.headers.get("ETag")
+        remote_etag = None
+        try:
+            r = requests.head(config.ics_url, headers=HEADERS, timeout=15, allow_redirects=True)
+            if r.status_code < 400:
+                remote_etag = r.headers.get("ETag")
+        except Exception:
+            pass
+
         cached_hash, cached_etag, _ = state.get_ics_cache()
 
         if remote_etag and cached_etag == remote_etag:
@@ -91,6 +96,8 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
         to_update = deltas["to_update"]
         to_delete = deltas["to_delete"]
 
+        is_first_run = not state.get_event_uids() and not cached_hash
+
         if not to_add and not to_update and not to_delete:
             logger.info("Calendar is already in sync.")
             duration = time.time() - start_time
@@ -100,6 +107,24 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
                 True,
                 len(ics_uids),
             )
+            for uid, h in ics_uids.items():
+                state.upsert_event(uid, h)
+            return True
+
+        if is_first_run and not to_delete:
+            logger.info(
+                "First run detected: %d events in ICS. Registering state without re-adding to calendar.",
+                len(to_add),
+            )
+            for uid, h in ics_uids.items():
+                state.upsert_event(uid, h)
+            duration = time.time() - start_time
+            health.update_status(
+                datetime.now(timezone.utc),
+                duration,
+                True,
+                len(ics_uids),
+            )
             return True
 
         logger.info(

From 20247c92c29a3b5d5b4fa7899a000aea0f472362 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Thu, 11 Jun 2026 23:07:10 +0200
Subject: [PATCH 5/7] docs: update README for v1.0.0 incremental sync

---
 README.md | 56 ++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/README.md b/README.md
index 373ae07..d46d3c6 100644
--- a/README.md
+++ b/README.md
@@ -1,61 +1,75 @@
 # Baïkal Calendar Sync
 
-A Dockerized Python service that periodically synchronizes an external Outlook ICS calendar to a local Baïkal CalDAV server.
+An incremental CalDAV sync service that keeps your Baïkal calendar in sync with an Outlook ICS feed — with zero downtime and near-instant sync times.
 
 ## Features
-- **Automatic Sync**: Runs periodically (default: every 5 minutes).
-- **Environment Configurable**: All credentials and URLs are set via environment variables.
-- **Docker Ready**: Includes `Dockerfile` and `docker-compose.yml` for easy deployment.
+
+- **Incremental Delta Sync**: Only adds, updates, or deletes events that actually changed
+- **Zero Downtime**: Adds/updates events before deleting removed ones — calendar never goes empty
+- **Smart Change Detection**: ETag check first, SHA-256 fallback. Skips sync when nothing changed
+- **Stable Event Hashing**: Ignores volatile fields (DTSTAMP, LAST-MODIFIED) to avoid false updates
+- **Automatic Backoff**: Exponential retry on failures (1m, 2m, 4m... max 30m)
+- **Health Endpoint**: Built-in `/health` and `/metrics` (Prometheus-compatible) on port 8081
+- **Graceful Shutdown**: SIGTERM/SIGINT handlers finish current sync before exiting
+- **Docker Ready**: Includes `Dockerfile`, `docker-compose.yml`, and HEALTHCHECK
 
 ## Prerequisites
-- Docker & Docker Compose installed.
-- An existing Baïkal instance.
-- An Outlook ICS link.
+
+- Docker & Docker Compose installed
+- An existing Baïkal instance
+- An Outlook ICS link
 
 ## Configuration (Environment Variables)
 
 | Variable | Description | Default |
 | :--- | :--- | :--- |
 | `ICS_URL` | The public ICS URL of your Outlook calendar. | **Required** |
-| `BAIKAL_URL` | The URL to your Baïkal calendar (e.g., `http://baikal/dav.php/calendars/user/id/`). | **Required** |
+| `BAIKAL_URL` | The URL to your Baïkal calendar. | **Required** |
 | `BAIKAL_USER` | Your Baïkal username. | **Required** |
 | `BAIKAL_PASS` | Your Baïkal password. | **Required** |
 | `SYNC_FREQUENCY` | How often to sync **in minutes**. | `5` |
+| `CALENDAR_ID` | Optional calendar ID to match against. | — |
 
-## Quick Start with Docker Compose
+## Quick Start
 
-1.  **Clone or download** this repository.
-2.  **Create a `.env` file** (optional but recommended) or export variables:
+1. **Clone or download** this repository.
+2. **Create a `.env` file** (optional but recommended):
 
     ```bash
-    ICS_URL="https://outlook.office365.com/..."
-    BAIKAL_URL="http://localhost:8080/dav.php/calendars/Lago/default/"
-    BAIKAL_USER="Lago"
-    BAIKAL_PASS="secret"
+    ICS_URL="https://outlook.office365.com/owa/calendar/your-calendar.ics"
+    BAIKAL_URL="https://your-baikal.com/dav.php/calendars/user/calendar-id/"
+    BAIKAL_USER="your-username"
+    BAIKAL_PASS="your-password"
     SYNC_FREQUENCY=5
     ```
 
-3.  **Run with Docker Compose**:
+3. **Run with Docker Compose**:
 
     ```bash
     docker compose up -d
     ```
-    *Note: This will verify the image usage. If you need to rebuild locally, run `docker compose up -d --build`.*
 
-4.  **Check Logs**:
+4. **Check Logs**:
 
     ```bash
     docker compose logs -f baikal-sync
     ```
 
-## Building & Publishing the Image
+5. **Check Health**:
 
-1.  **Build**:
+    ```bash
+    curl http://localhost:8081/health
+    curl http://localhost:8081/metrics
+    ```
+
+## Building & Publishing
+
+1. **Build**:
     ```bash
     docker build -t lagortinez/baikal-sync:latest .
     ```
 
-2.  **Push** (requires `docker login`):
+2. **Push**:
     ```bash
     docker push lagortinez/baikal-sync:latest
     ```

From 7a388653edb8ecf538d5a848a372d70a905a5546 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Fri, 12 Jun 2026 08:11:24 +0200
Subject: [PATCH 6/7] feat: dashboard UI with real-time stats, light/dark mode,
 session metrics

---
 Dockerfile            |   2 +
 dashboard.py          | 146 +++++++++
 docker-compose.yml    |   3 +
 health.py             |  73 +++++
 static/dashboard.html | 731 ++++++++++++++++++++++++++++++++++++++++++
 sync_calendar.py      | 141 +++++---
 6 files changed, 1050 insertions(+), 46 deletions(-)
 create mode 100644 dashboard.py
 create mode 100644 static/dashboard.html

diff --git a/Dockerfile b/Dockerfile
index db4d074..961f932 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,6 +9,8 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
 
+EXPOSE 8081 8082
+
 HEALTHCHECK --interval=60s --timeout=10s --start-period=5s --retries=3 \
     CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8081/health')" || exit 1
 
diff --git a/dashboard.py b/dashboard.py
new file mode 100644
index 0000000..11520f0
--- /dev/null
+++ b/dashboard.py
@@ -0,0 +1,146 @@
+import json
+import os
+import threading
+from http.server import HTTPServer, BaseHTTPRequestHandler
+
+from health import HealthServer, SyncSession
+
+
+class DashboardServer:
+    def __init__(self, port: int = 8082, health: HealthServer = None, session: SyncSession = None):
+        self.port = port
+        self.health = health
+        self.session = session
+        self.server = None
+        self.thread = None
+        self._lock = threading.Lock()
+        self._syncing = False
+        self._next_sync_in = 0
+        self._event_count = 0
+        self._backoff_min = 0
+        self._config = {}
+        self._base_dir = os.path.dirname(os.path.abspath(__file__))
+
+    def start(self):
+        handler = self._make_handler()
+        self.server = HTTPServer(("0.0.0.0", self.port), handler)
+        self.thread = threading.Thread(target=self.server.serve_forever, daemon=True)
+        self.thread.start()
+
+    def stop(self):
+        if self.server:
+            self.server.shutdown()
+            self.server = None
+            self.thread = None
+
+    def update_config(self, config_dict: dict):
+        with self._lock:
+            self._config = dict(config_dict)
+
+    def set_syncing(self, syncing: bool):
+        with self._lock:
+            self._syncing = syncing
+
+    def set_next_sync_in(self, seconds: int):
+        with self._lock:
+            self._next_sync_in = seconds
+
+    def set_event_count(self, n: int):
+        with self._lock:
+            self._event_count = n
+
+    def set_backoff_min(self, n: int):
+        with self._lock:
+            self._backoff_min = n
+
+    def _get_status(self):
+        with self._lock:
+            syncing = self._syncing
+            next_sync_in = self._next_sync_in
+            event_count = self._event_count
+            backoff_min = self._backoff_min
+            config = dict(self._config)
+
+        last_sync = None
+        duration = 0.0
+        last_success = None
+        if self.health:
+            with self.health.lock:
+                last_sync = self.health.last_sync
+                duration = self.health.last_sync_duration
+                last_success = self.health.last_sync_success
+
+        status = "idle"
+        if syncing:
+            status = "syncing"
+        elif last_success is False:
+            status = "error"
+        elif backoff_min > 0:
+            status = "backoff"
+
+        session_data = {}
+        history = []
+        if self.session:
+            session_data = self.session.get_status()
+            history = session_data.get("history", [])
+
+        ics_latency = 0.0
+        if self.session and self.session.non_skip_count > 0:
+            ics_latency = round(self.session.total_latency_ms / self.session.non_skip_count)
+
+        return {
+            "status": status,
+            "last_sync": last_sync.isoformat() if last_sync else None,
+            "duration": duration,
+            "ics_latency_ms": ics_latency,
+            "event_count": event_count,
+            "next_sync_in": next_sync_in,
+            "session": session_data,
+            "history": history,
+            "config": config,
+        }
+
+    def _make_handler(self):
+        server_self = self
+        base_dir = server_self._base_dir
+
+        class Handler(BaseHTTPRequestHandler):
+            def do_GET(self):
+                if self.path == "/api/status":
+                    self._handle_api(server_self)
+                elif self.path == "/":
+                    self._handle_dashboard(base_dir)
+                else:
+                    self.send_response(404)
+                    self.send_header("Content-Type", "application/json")
+                    self.end_headers()
+                    self.wfile.write(json.dumps({"error": "not found"}).encode())
+
+            def _handle_api(self, srv):
+                data = srv._get_status()
+                body = json.dumps(data).encode()
+                self.send_response(200)
+                self.send_header("Content-Type", "application/json")
+                self.end_headers()
+                self.wfile.write(body)
+
+            def _handle_dashboard(self, base):
+                html_path = os.path.join(base, "static", "dashboard.html")
+                try:
+                    with open(html_path, "r", encoding="utf-8") as f:
+                        content = f.read()
+                    body = content.encode("utf-8")
+                    self.send_response(200)
+                    self.send_header("Content-Type", "text/html; charset=utf-8")
+                    self.end_headers()
+                    self.wfile.write(body)
+                except FileNotFoundError:
+                    self.send_response(404)
+                    self.send_header("Content-Type", "application/json")
+                    self.end_headers()
+                    self.wfile.write(json.dumps({"error": "dashboard not found"}).encode())
+
+            def log_message(self, format, *args):
+                pass
+
+        return Handler
diff --git a/docker-compose.yml b/docker-compose.yml
index 659d65a..0477a35 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -3,6 +3,9 @@ services:
     image: lagortinez/baikal-sync:latest
     container_name: baikal-sync
     restart: always
+    ports:
+      - "8081:8081"
+      - "8082:8082"
     environment:
       - ICS_URL=${ICS_URL}
       - BAIKAL_URL=${BAIKAL_URL}
diff --git a/health.py b/health.py
index d20cebc..b220e91 100644
--- a/health.py
+++ b/health.py
@@ -1,10 +1,83 @@
 import json
 import threading
+import time
+from collections import deque
 from datetime import datetime, timezone
 from http.server import HTTPServer, BaseHTTPRequestHandler
 from io import StringIO
 
 
+class SyncSession:
+    def __init__(self):
+        self._lock = threading.Lock()
+        self.start_time = time.time()
+        self.syncs_total = 0
+        self.syncs_failed = 0
+        self.syncs_skipped = 0
+        self.total_added = 0
+        self.total_updated = 0
+        self.total_deleted = 0
+        self.total_duration = 0.0
+        self.total_latency_ms = 0.0
+        self.non_skip_count = 0
+        self.bandwidth_bytes = 0
+        self.bandwidth_saved_bytes = 0
+        self.history = deque(maxlen=50)
+
+    def record(self, ok: bool, duration: float, added: int, updated: int, deleted: int, skipped: bool, ics_latency_ms: float, msg: str, ics_download_size: int = 0) -> None:
+        with self._lock:
+            self.syncs_total += 1
+            ts = time.strftime("%H:%M:%S", time.gmtime())
+            if not ok:
+                self.syncs_failed += 1
+            if skipped:
+                self.syncs_skipped += 1
+            self.total_added += added
+            self.total_updated += updated
+            self.total_deleted += deleted
+            if not skipped:
+                self.non_skip_count += 1
+            self.total_duration += duration
+            self.total_latency_ms += ics_latency_ms
+            if ics_download_size:
+                self.bandwidth_bytes += ics_download_size
+            self.history.append({
+                "time": ts,
+                "ok": ok,
+                "duration": round(duration, 2),
+                "added": added,
+                "updated": updated,
+                "deleted": deleted,
+                "skipped": skipped,
+                "latency_ms": round(ics_latency_ms),
+                "msg": msg,
+            })
+
+    def get_status(self) -> dict:
+        with self._lock:
+            uptime = time.time() - self.start_time
+            avg_dur = round(self.total_duration / self.non_skip_count, 2) if self.non_skip_count > 0 else 0
+            avg_lat = round(self.total_latency_ms / self.non_skip_count) if self.non_skip_count > 0 else 0
+            return {
+                "uptime_sec": round(uptime),
+                "syncs_total": self.syncs_total,
+                "syncs_failed": self.syncs_failed,
+                "syncs_skipped": self.syncs_skipped,
+                "total_added": self.total_added,
+                "total_updated": self.total_updated,
+                "total_deleted": self.total_deleted,
+                "avg_duration": avg_dur,
+                "avg_latency_ms": avg_lat,
+                "bandwidth_bytes": self.bandwidth_bytes,
+                "bandwidth_saved_bytes": self.bandwidth_saved_bytes,
+                "history": list(self.history),
+            }
+
+    def add_saved_bandwidth(self, bytes_saved: int) -> None:
+        with self._lock:
+            self.bandwidth_saved_bytes += bytes_saved
+
+
 class HealthServer:
     def __init__(self, port: int = 8081):
         self.port = port
diff --git a/static/dashboard.html b/static/dashboard.html
new file mode 100644
index 0000000..a5e34f4
--- /dev/null
+++ b/static/dashboard.html
@@ -0,0 +1,731 @@
+<!DOCTYPE html>
+<html lang="en" data-theme="dark">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<title>Baikal Sync Dashboard</title>
+<style>
+*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
+
+:root {
+  --transition: 0.3s ease;
+  --green: #00b894;
+  --blue: #74b9ff;
+  --yellow: #fdcb6e;
+  --red: #e17055;
+  --purple: #a29bfe;
+}
+
+[data-theme="dark"] {
+  --bg: #0f1117;
+  --card: #1a1d27;
+  --border: #2e3345;
+  --text: #e4e6f0;
+  --text-secondary: #8b90a0;
+  --shadow: 0 2px 12px rgba(0,0,0,0.3);
+  --chart-bg: #12141c;
+}
+
+[data-theme="light"] {
+  --bg: #f5f7fa;
+  --card: #ffffff;
+  --border: #e2e8f0;
+  --text: #1a1d27;
+  --text-secondary: #64748b;
+  --shadow: 0 2px 12px rgba(0,0,0,0.08);
+  --chart-bg: #f0f3f8;
+}
+
+body {
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
+  background: var(--bg);
+  color: var(--text);
+  line-height: 1.6;
+  transition: background var(--transition), color var(--transition);
+  min-height: 100vh;
+}
+
+.container { max-width: 1200px; margin: 0 auto; padding: 24px 16px; }
+
+header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 28px;
+}
+
+.logo { display: flex; align-items: center; gap: 10px; font-size: 1.5rem; font-weight: 700; }
+
+.status-dot {
+  width: 12px; height: 12px; border-radius: 50%; background: var(--green);
+  animation: pulse 2s ease-in-out infinite;
+}
+
+.status-dot.error { background: var(--red); }
+.status-dot.syncing { background: var(--blue); animation-duration: 0.6s; }
+.status-dot.backoff { background: var(--yellow); }
+
+@keyframes pulse {
+  0%, 100% { box-shadow: 0 0 0 0 rgba(0,184,148,0.5); }
+  50% { box-shadow: 0 0 0 8px rgba(0,184,148,0); }
+}
+
+.theme-toggle {
+  background: var(--card); border: 1px solid var(--border); border-radius: 8px;
+  width: 40px; height: 40px; cursor: pointer; display: flex;
+  align-items: center; justify-content: center; font-size: 1.2rem;
+  transition: background var(--transition), border-color var(--transition);
+}
+
+.theme-toggle:hover { border-color: var(--text-secondary); }
+
+.card {
+  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
+  padding: 20px; transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
+  box-shadow: var(--shadow);
+}
+
+.status-bar { margin-bottom: 24px; }
+
+.status-main {
+  display: flex; align-items: center; justify-content: space-between;
+  flex-wrap: wrap; gap: 12px; margin-bottom: 16px;
+}
+
+.status-text { font-size: 1.35rem; font-weight: 600; }
+
+.status-meta { display: flex; gap: 20px; flex-wrap: wrap; color: var(--text-secondary); font-size: 0.9rem; }
+
+.countdown-bar { margin-top: 12px; }
+
+.countdown-label { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 6px; display: flex; justify-content: space-between; }
+
+.progress-track {
+  height: 6px; background: var(--border); border-radius: 3px; overflow: hidden;
+}
+
+.progress-fill {
+  height: 100%; background: var(--green); border-radius: 3px;
+  transition: width 1s linear;
+}
+
+.stats-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
+  gap: 16px; margin-bottom: 24px;
+}
+
+.stat-card { padding: 18px; }
+
+.stat-label { font-size: 0.8rem; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 8px; }
+
+.stat-value { font-size: 1.7rem; font-weight: 700; }
+
+.stat-sub { font-size: 0.8rem; color: var(--text-secondary); margin-top: 4px; }
+
+.stat-card.green .stat-value { color: var(--green); }
+.stat-card.blue .stat-value { color: var(--blue); }
+.stat-card.yellow .stat-value { color: var(--yellow); }
+.stat-card.red .stat-value { color: var(--red); }
+.stat-card.purple .stat-value { color: var(--purple); }
+
+.section-card { margin-bottom: 24px; }
+.section-title { font-size: 1.05rem; font-weight: 600; margin-bottom: 16px; }
+
+.stacked-bar-container { margin-bottom: 20px; }
+
+.stacked-bar {
+  height: 32px; border-radius: 6px; overflow: hidden; display: flex;
+  background: var(--border);
+}
+
+.stacked-segment { height: 100%; transition: width 0.5s ease; min-width: 0; }
+
+.legend {
+  display: flex; gap: 16px; flex-wrap: wrap; margin-top: 10px;
+  font-size: 0.85rem; color: var(--text-secondary);
+}
+
+.legend-item { display: flex; align-items: center; gap: 6px; }
+
+.legend-dot { width: 10px; height: 10px; border-radius: 50%; }
+
+.toggle-group {
+  display: flex; gap: 4px; margin-bottom: 16px;
+  background: var(--border); border-radius: 8px; padding: 3px; width: fit-content;
+}
+
+.toggle-btn {
+  background: transparent; border: none; color: var(--text-secondary);
+  padding: 6px 14px; border-radius: 6px; cursor: pointer; font-size: 0.85rem;
+  transition: all var(--transition);
+}
+
+.toggle-btn.active { background: var(--card); color: var(--text); font-weight: 600; }
+
+.chart-area {
+  display: flex; align-items: flex-end; gap: 2px; height: 120px;
+  background: var(--chart-bg); border-radius: 8px; padding: 8px; overflow: hidden;
+}
+
+.chart-bar {
+  flex: 1; border-radius: 2px 2px 0 0; transition: height 0.3s ease, background 0.3s ease;
+  min-width: 3px; position: relative;
+}
+
+.chart-bar.ok { background: var(--green); }
+.chart-bar.fail { background: var(--red); }
+
+.chart-labels {
+  display: flex; justify-content: space-between; margin-top: 4px;
+  font-size: 0.7rem; color: var(--text-secondary);
+}
+
+.config-section { margin-bottom: 24px; }
+
+.copy-btn {
+  background: var(--green); color: #fff; border: none; border-radius: 8px;
+  padding: 8px 18px; cursor: pointer; font-size: 0.9rem; font-weight: 600;
+  transition: opacity var(--transition); margin-bottom: 16px;
+}
+
+.copy-btn:hover { opacity: 0.85; }
+.copy-btn.copied { background: var(--blue); }
+
+.config-table { width: 100%; border-collapse: collapse; }
+
+.config-table td {
+  padding: 10px 12px; border-bottom: 1px solid var(--border);
+  font-size: 0.9rem;
+}
+
+.config-table tr:last-child td { border-bottom: none; }
+
+.config-table td:first-child {
+  color: var(--text-secondary); font-weight: 500; width: 140px;
+  white-space: nowrap;
+}
+
+.config-table td:last-child { word-break: break-all; }
+
+.password-cell { display: flex; align-items: center; gap: 8px; }
+
+.password-text { flex: 1; }
+
+.eye-btn {
+  background: none; border: none; cursor: pointer; font-size: 1.1rem;
+  opacity: 0.6; transition: opacity var(--transition); padding: 4px;
+}
+
+.eye-btn:hover { opacity: 1; }
+
+.history-section { margin-bottom: 24px; }
+
+.timeline { display: flex; flex-direction: column; gap: 6px; max-height: 400px; overflow-y: auto; }
+
+.timeline-entry {
+  display: flex; align-items: center; gap: 10px; padding: 10px 14px;
+  border-radius: 8px; background: var(--chart-bg); font-size: 0.88rem;
+  transition: background var(--transition);
+}
+
+.entry-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
+
+.entry-dot.ok { background: var(--green); }
+.entry-dot.fail { background: var(--red); }
+
+.entry-time { color: var(--text-secondary); font-variant-numeric: tabular-nums; min-width: 60px; }
+
+.entry-msg { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+
+.badge {
+  padding: 2px 8px; border-radius: 4px; font-size: 0.78rem; font-weight: 600;
+  white-space: nowrap;
+}
+
+.badge.added { background: rgba(0,184,148,0.15); color: var(--green); }
+.badge.updated { background: rgba(116,185,255,0.15); color: var(--blue); }
+.badge.skipped { background: rgba(139,144,160,0.15); color: var(--text-secondary); }
+.badge.error { background: rgba(225,112,85,0.15); color: var(--red); }
+
+.empty-state {
+  text-align: center; padding: 40px 20px; color: var(--text-secondary);
+  font-size: 0.95rem;
+}
+
+@media (max-width: 768px) {
+  .stats-grid { grid-template-columns: repeat(2, 1fr); }
+  .status-main { flex-direction: column; align-items: flex-start; }
+  .status-meta { flex-direction: column; gap: 4px; }
+}
+
+@media (max-width: 480px) {
+  .stats-grid { grid-template-columns: 1fr; }
+}
+</style>
+</head>
+<body>
+<div class="container">
+  <header>
+    <div class="logo">
+      <span class="status-dot" id="headerDot"></span>
+      Baikal Sync
+    </div>
+    <button class="theme-toggle" id="themeToggle" aria-label="Toggle theme">🌙</button>
+  </header>
+
+  <div class="card status-bar" id="statusBar">
+    <div class="empty-state">Loading…</div>
+  </div>
+
+  <div class="stats-grid" id="statsGrid">
+    <div class="card stat-card green"><div class="stat-label">Total Events</div><div class="stat-value" id="statEvents">—</div></div>
+    <div class="card stat-card blue"><div class="stat-label">Total Added</div><div class="stat-value" id="statAdded">—</div></div>
+    <div class="card stat-card purple"><div class="stat-label">Avg Events/Sync</div><div class="stat-value" id="statAvgEvents">—</div></div>
+    <div class="card stat-card blue"><div class="stat-label">Syncs Total</div><div class="stat-value" id="statSyncs">—</div><div class="stat-sub" id="statSyncsSub"></div></div>
+    <div class="card stat-card yellow"><div class="stat-label">Avg Sync Time</div><div class="stat-value" id="statAvgDuration">—</div></div>
+    <div class="card stat-card purple"><div class="stat-label">Avg Latency</div><div class="stat-value" id="statAvgLatency">—</div></div>
+    <div class="card stat-card green"><div class="stat-label">Bandwidth Saved</div><div class="stat-value" id="statBandwidth">—</div></div>
+    <div class="card stat-card" id="backoffCard"><div class="stat-label">Backoff</div><div class="stat-value" id="statBackoff">—</div></div>
+  </div>
+
+  <div class="card section-card">
+    <div class="section-title">Session Breakdown</div>
+    <div class="stacked-bar-container">
+      <div class="stacked-bar" id="stackedBar"></div>
+      <div class="legend" id="stackedLegend"></div>
+    </div>
+    <div class="toggle-group" id="chartToggle">
+      <button class="toggle-btn active" data-metric="duration">Duration</button>
+      <button class="toggle-btn" data-metric="events">Events</button>
+      <button class="toggle-btn" data-metric="latency">Latency</button>
+    </div>
+    <div class="chart-area" id="chartArea"></div>
+    <div class="chart-labels" id="chartLabels"></div>
+  </div>
+
+  <div class="card config-section">
+    <div class="section-title">Configuration</div>
+    <button class="copy-btn" id="copyBtn">Copy .env</button>
+    <table class="config-table" id="configTable">
+      <tbody id="configBody"></tbody>
+    </table>
+  </div>
+
+  <div class="card history-section">
+    <div class="section-title">Sync History</div>
+    <div class="timeline" id="timeline">
+      <div class="empty-state">No sync history yet.</div>
+    </div>
+  </div>
+</div>
+
+<script>
+(function () {
+  "use strict";
+
+  const state = {
+    data: null,
+    chartMetric: "duration",
+    passwordVisible: false,
+    pollTimer: null,
+    countdownTimer: null,
+    lastPoll: null
+  };
+
+  const $ = (sel) => document.querySelector(sel);
+
+  function fmtBytes(b) {
+    if (b == null || b === 0) return "0 B";
+    if (b >= 1048576) return (b / 1048576).toFixed(2) + " MB";
+    return (b / 1024).toFixed(1) + " KB";
+  }
+
+  function fmtUptime(sec) {
+    if (sec == null) return "—";
+    const h = Math.floor(sec / 3600);
+    const m = Math.floor((sec % 3600) / 60);
+    return h + "h " + m + "m";
+  }
+
+  function fmtDuration(s) {
+    if (s == null) return "—";
+    if (s < 1) return (s * 1000).toFixed(0) + "ms";
+    return s.toFixed(2) + "s";
+  }
+
+  function fmtTime(iso) {
+    if (!iso) return "Never";
+    try {
+      const d = new Date(iso);
+      return d.toLocaleTimeString();
+    } catch { return iso; }
+  }
+
+  function fmtCountdown(sec) {
+    if (sec == null || sec < 0) return "00:00";
+    const m = Math.floor(sec / 60);
+    const s = sec % 60;
+    return String(m).padStart(2, "0") + ":" + String(s).padStart(2, "0");
+  }
+
+  function truncate(str, max) {
+    if (!str) return "";
+    max = max || 60;
+    return str.length > max ? str.slice(0, 30) + "…" : str;
+  }
+
+  function maskPassword(p) {
+    if (!p) return "";
+    return "•".repeat(Math.min(p.length, 20));
+  }
+
+  function getStatusLabel(s) {
+    switch (s) {
+      case "syncing": return "Syncing…";
+      case "error": return "Error";
+      case "backoff": return "Backing off";
+      case "idle":
+      default: return "Up to Date";
+    }
+  }
+
+  function getSyncStatusClass(s) {
+    switch (s) {
+      case "syncing": return "syncing";
+      case "error": return "error";
+      case "backoff": return "backoff";
+      default: return "";
+    }
+  }
+
+  /* ── Theme ── */
+  function initTheme() {
+    const saved = localStorage.getItem("baikal-theme");
+    const theme = saved || "dark";
+    document.documentElement.setAttribute("data-theme", theme);
+    $("#themeToggle").textContent = theme === "dark" ? "☀️" : "🌙";
+  }
+
+  function toggleTheme() {
+    const current = document.documentElement.getAttribute("data-theme");
+    const next = current === "dark" ? "light" : "dark";
+    document.documentElement.setAttribute("data-theme", next);
+    localStorage.setItem("baikal-theme", next);
+    $("#themeToggle").textContent = next === "dark" ? "☀️" : "🌙";
+  }
+
+  /* ── Render Status Bar ── */
+  function renderStatusBar(d) {
+    const cls = getSyncStatusClass(d.status);
+    $("#headerDot").className = "status-dot" + (cls ? " " + cls : "");
+
+    let statusText = "";
+    if (d.status === "backoff" && d.next_sync_in != null) {
+      const mins = Math.ceil(d.next_sync_in / 60);
+      statusText = "Backing off — " + mins + " min remaining";
+    } else {
+      statusText = "Sync " + getStatusLabel(d.status);
+    }
+
+    const progressPct = d.next_sync_in != null && d.config && d.config.sync_frequency
+      ? Math.max(0, Math.min(100, ((d.config.sync_frequency * 60 - d.next_sync_in) / (d.config.sync_frequency * 60)) * 100))
+      : 0;
+
+    $("#statusBar").innerHTML =
+      '<div class="status-main">' +
+        '<div class="status-text">' + statusText + "</div>" +
+        '<div class="status-meta">' +
+          '<span>Last sync: ' + fmtTime(d.last_sync) + "</span>" +
+          (d.duration != null ? '<span>Duration: ' + fmtDuration(d.duration) + "</span>" : "") +
+          (d.ics_latency_ms != null ? '<span>Latency: ' + d.ics_latency_ms + "ms</span>" : "") +
+          '<span>Uptime: ' + fmtUptime(d.session.uptime_sec) + "</span>" +
+        "</div>" +
+      "</div>" +
+      '<div class="countdown-bar">' +
+        '<div class="countdown-label">' +
+          '<span>Next sync</span><span id="countdown">' + fmtCountdown(d.next_sync_in) + "</span>" +
+        "</div>" +
+        '<div class="progress-track"><div class="progress-fill" id="progressFill" style="width:' + progressPct + '%"></div></div>' +
+      "</div>";
+  }
+
+  /* ── Render Stats ── */
+  function renderStats(d) {
+    const s = d.session;
+    $("#statEvents").textContent = d.event_count != null ? d.event_count : "—";
+    $("#statAdded").textContent = s.total_added != null ? s.total_added : "—";
+
+    const totalOps = (s.total_added || 0) + (s.total_updated || 0);
+    const avgEvents = s.syncs_total > 0 ? (totalOps / s.syncs_total).toFixed(2) : "—";
+    $("#statAvgEvents").textContent = avgEvents;
+
+    $("#statSyncs").textContent = s.syncs_total || 0;
+    const skipPct = s.syncs_total > 0 ? ((s.syncs_skipped || 0) / s.syncs_total * 100).toFixed(0) : "0";
+    $("#statSyncsSub").textContent = (s.syncs_failed || 0) + " failed · " + skipPct + "% skipped";
+
+    $("#statAvgDuration").textContent = fmtDuration(s.avg_duration);
+    $("#statAvgLatency").textContent = s.avg_latency_ms != null ? s.avg_latency_ms + " ms" : "—";
+    $("#statBandwidth").textContent = fmtBytes(s.bandwidth_saved_bytes);
+
+    const bc = $("#backoffCard");
+    if (d.status === "backoff") {
+      bc.className = "card stat-card yellow";
+      const mins = Math.ceil((d.next_sync_in || 0) / 60);
+      $("#statBackoff").textContent = mins + " min";
+    } else {
+      bc.className = "card stat-card green";
+      $("#statBackoff").textContent = "None";
+    }
+  }
+
+  /* ── Render Stacked Bar ── */
+  function renderStackedBar(d) {
+    const s = d.session;
+    const added = s.total_added || 0;
+    const updated = s.total_updated || 0;
+    const deleted = s.total_deleted || 0;
+    const skipped = s.syncs_skipped || 0;
+    const total = added + updated + deleted + skipped || 1;
+
+    const w1 = (added / total * 100).toFixed(2);
+    const w2 = (updated / total * 100).toFixed(2);
+    const w3 = (deleted / total * 100).toFixed(2);
+    const w4 = (skipped / total * 100).toFixed(2);
+
+    $("#stackedBar").innerHTML =
+      '<div class="stacked-segment" style="width:' + w1 + '%;background:var(--green)"></div>' +
+      '<div class="stacked-segment" style="width:' + w2 + '%;background:var(--blue)"></div>' +
+      '<div class="stacked-segment" style="width:' + w3 + '%;background:var(--purple)"></div>' +
+      '<div class="stacked-segment" style="width:' + w4 + '%;background:var(--text-secondary)"></div>';
+
+    $("#stackedLegend").innerHTML =
+      '<div class="legend-item"><span class="legend-dot" style="background:var(--green)"></span>Added: ' + added + "</div>" +
+      '<div class="legend-item"><span class="legend-dot" style="background:var(--blue)"></span>Updated: ' + updated + "</div>" +
+      '<div class="legend-item"><span class="legend-dot" style="background:var(--purple)"></span>Deleted: " + deleted + "</div>" +
+      '<div class="legend-item"><span class="legend-dot" style="background:var(--text-secondary)"></span>Skipped: ' + skipped + "</div>";
+  }
+
+  /* ── Render Chart ── */
+  function renderChart(d) {
+    const history = d.session.history || [];
+    const metric = state.chartMetric;
+    const sliced = history.slice(-50);
+    if (!sliced.length) {
+      $("#chartArea").innerHTML = "";
+      $("#chartLabels").innerHTML = "";
+      return;
+    }
+
+    let key = "";
+    if (metric === "duration") key = "duration";
+    else if (metric === "events") {
+      const vals = sliced.map(function (e) { return (e.added || 0) + (e.updated || 0) + (e.deleted || 0); });
+      const maxVal = Math.max(1, ...vals);
+      const bars = sliced.map(function (e, i) {
+        const v = (e.added || 0) + (e.updated || 0) + (e.deleted || 0);
+        const h = Math.max(2, (v / maxVal) * 100);
+        return '<div class="chart-bar ' + (e.ok ? "ok" : "fail") + '" style="height:' + h + '%" title="' + v + ' events"></div>';
+      }).join("");
+      $("#chartArea").innerHTML = bars;
+      const first = sliced[0];
+      const last = sliced[sliced.length - 1];
+      $("#chartLabels").innerHTML = '<span>' + (first.time || "") + "</span><span>" + (last.time || "") + "</span>";
+      return;
+    } else { key = "latency_ms"; }
+
+    const vals = sliced.map(function (e) { return e[key] || 0; });
+    const maxVal = Math.max(1, ...vals);
+
+    const bars = sliced.map(function (e) {
+      const v = e[key] || 0;
+      const h = Math.max(2, (v / maxVal) * 100);
+      const tip = metric === "duration" ? (v * 1000).toFixed(0) + "ms" : v + "ms";
+      return '<div class="chart-bar ' + (e.ok ? "ok" : "fail") + '" style="height:' + h + '%" title="' + tip + '"></div>';
+    }).join("");
+
+    $("#chartArea").innerHTML = bars;
+    const first = sliced[0];
+    const last = sliced[sliced.length - 1];
+    $("#chartLabels").innerHTML = '<span>' + (first.time || "") + "</span><span>" + (last.time || "") + "</span>";
+  }
+
+  /* ── Render Config ── */
+  function renderConfig(d) {
+    const c = d.config || {};
+    const rows = [
+      ["ICS URL", truncate(c.ics_url || "")],
+      ["Baikal URL", truncate(c.baikal_url || "")],
+      ["User", c.baikal_user || ""],
+      ["Password", "password", c.baikal_pass || ""],
+      ["Frequency", c.sync_frequency ? c.sync_frequency + " minutes" : "—"],
+      ["Calendar ID", c.calendar_id || "—"]
+    ];
+
+    let html = "";
+    rows.forEach(function (r) {
+      if (r[1] === "password") {
+        const pw = state.passwordVisible ? r[2] : maskPassword(r[2]);
+        html += '<tr><td>' + r[0] + "</td><td>" +
+          '<div class="password-cell">' +
+          '<span class="password-text">' + pw + "</span>" +
+          '<button class="eye-btn" id="eyeBtn">' + (state.passwordVisible ? "🙈" : "👁️") + "</button>" +
+          "</div></td></tr>";
+      } else {
+        html += '<tr><td>' + r[0] + "</td><td>" + r[1] + "</td></tr>";
+      }
+    });
+    $("#configBody").innerHTML = html;
+
+    if ($("#eyeBtn")) {
+      $("#eyeBtn").addEventListener("click", function () {
+        state.passwordVisible = !state.passwordVisible;
+        renderConfig(state.data);
+      });
+    }
+  }
+
+  /* ── Render History ── */
+  function renderHistory(d) {
+    const history = d.session.history || [];
+    const sliced = history.slice(-50).reverse();
+    if (!sliced.length) {
+      $("#timeline").innerHTML = '<div class="empty-state">No sync history yet.</div>';
+      return;
+    }
+
+    let html = "";
+    sliced.forEach(function (entry) {
+      const ok = entry.ok !== false;
+      const badge = getBadge(entry);
+      html +=
+        '<div class="timeline-entry">' +
+          '<span class="entry-dot ' + (ok ? "ok" : "fail") + '"></span>' +
+          '<span class="entry-time">' + (entry.time || "") + "</span>" +
+          '<span class="entry-msg">' + escapeHtml(entry.msg || (ok ? "OK" : "Error")) + "</span>" +
+          badge +
+        "</div>";
+    });
+    $("#timeline").innerHTML = html;
+  }
+
+  function getBadge(e) {
+    const added = e.added || 0;
+    const updated = e.updated || 0;
+    const deleted = e.deleted || 0;
+    if (!e.ok) return '<span class="badge error">error</span>';
+    if (e.skipped || (added === 0 && updated === 0 && deleted === 0)) return '<span class="badge skipped">skipped</span>';
+    const parts = [];
+    if (added) parts.push("+" + added);
+    if (updated) parts.push("~" + updated);
+    if (deleted) parts.push("−" + deleted);
+    return '<span class="badge ' + (added ? "added" : "updated") + '">' + parts.join(" / ") + "</span>";
+  }
+
+  function escapeHtml(str) {
+    const div = document.createElement("div");
+    div.textContent = str;
+    return div.innerHTML;
+  }
+
+  /* ── Copy .env ── */
+  function copyEnv() {
+    const c = state.data.config;
+    if (!c) return;
+    const lines = [
+      "ICS_URL=" + (c.ics_url || ""),
+      "BAIKAL_URL=" + (c.baikal_url || ""),
+      "BAIKAL_USER=" + (c.baikal_user || ""),
+      "BAIKAL_PASS=" + (c.baikal_pass || ""),
+      "SYNC_FREQUENCY=" + (c.sync_frequency || ""),
+      "CALENDAR_ID=" + (c.calendar_id || "")
+    ].join("\n");
+
+    navigator.clipboard.writeText(lines).then(function () {
+      const btn = $("#copyBtn");
+      btn.textContent = "Copied!";
+      btn.classList.add("copied");
+      setTimeout(function () {
+        btn.textContent = "Copy .env";
+        btn.classList.remove("copied");
+      }, 2000);
+    }).catch(function () {
+      const ta = document.createElement("textarea");
+      ta.value = lines;
+      document.body.appendChild(ta);
+      ta.select();
+      document.execCommand("copy");
+      document.body.removeChild(ta);
+      const btn = $("#copyBtn");
+      btn.textContent = "Copied!";
+      btn.classList.add("copied");
+      setTimeout(function () {
+        btn.textContent = "Copy .env";
+        btn.classList.remove("copied");
+      }, 2000);
+    });
+  }
+
+  /* ── Polling ── */
+  function updateCountdown() {
+    if (!state.data) return;
+    const el = $("#countdown");
+    const fill = $("#progressFill");
+    if (!el || !fill) return;
+
+    let remaining = (state.data.next_sync_in || 0) - 1;
+    if (remaining < 0) remaining = 0;
+    el.textContent = fmtCountdown(remaining);
+
+    const freq = state.data.config ? state.data.config.sync_frequency * 60 : 600;
+    const pct = freq > 0 ? Math.max(0, Math.min(100, ((freq - remaining) / freq) * 100)) : 100;
+    fill.style.width = pct + "%";
+    state.data.next_sync_in = remaining;
+  }
+
+  async function poll() {
+    try {
+      const res = await fetch("/api/status");
+      if (!res.ok) throw new Error("HTTP " + res.status);
+      state.data = await res.json();
+      state.lastPoll = Date.now();
+      renderStatusBar(state.data);
+      renderStats(state.data);
+      renderStackedBar(state.data);
+      renderChart(state.data);
+      renderConfig(state.data);
+      renderHistory(state.data);
+    } catch (err) {
+      console.error("Poll error:", err);
+    }
+  }
+
+  /* ── Init ── */
+  function init() {
+    initTheme();
+    $("#themeToggle").addEventListener("click", toggleTheme);
+    $("#copyBtn").addEventListener("click", copyEnv);
+
+    document.getElementById("chartToggle").addEventListener("click", function (e) {
+      const btn = e.target.closest(".toggle-btn");
+      if (!btn) return;
+      state.chartMetric = btn.getAttribute("data-metric");
+      document.querySelectorAll("#chartToggle .toggle-btn").forEach(function (b) { b.classList.remove("active"); });
+      btn.classList.add("active");
+      if (state.data) renderChart(state.data);
+    });
+
+    poll();
+    state.pollTimer = setInterval(poll, 10000);
+    state.countdownTimer = setInterval(updateCountdown, 1000);
+  }
+
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", init);
+  } else {
+    init();
+  }
+})();
+</script>
+</body>
+</html>
diff --git a/sync_calendar.py b/sync_calendar.py
index b265ab0..7ce64de 100644
--- a/sync_calendar.py
+++ b/sync_calendar.py
@@ -12,7 +12,8 @@ from config import validate, HEADERS, Config
 from state import SyncState
 from diff import parse_ics_events, compute_diff, parse_ics_events_with_data
 from apply import apply_adds, apply_updates, apply_deletes
-from health import HealthServer
+from health import HealthServer, SyncSession
+from dashboard import DashboardServer
 
 logger = logging.getLogger(__name__)
 shutdown_event = threading.Event()
@@ -51,8 +52,23 @@ def find_calendar(client, config):
     return None
 
 
-def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
+def sync_once(
+    state: SyncState,
+    health: HealthServer,
+    session: SyncSession,
+    config: Config,
+    dashboard: DashboardServer,
+) -> bool:
     start_time = time.time()
+    ics_latency_ms = 0
+    added = 0
+    updated = 0
+    deleted = 0
+    skipped = False
+    ics_download_size = 0
+    msg = ""
+
+    dashboard.set_syncing(True)
     logger.info("Starting sync cycle...")
 
     try:
@@ -68,17 +84,35 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
 
         if remote_etag and cached_etag == remote_etag:
             logger.info("No changes detected (ETag match). Skipping sync.")
+            duration = time.time() - start_time
+            skipped = True
+            msg = "no changes (ETag)"
+            session.record(True, duration, 0, 0, 0, True, 0, msg)
+            health.update_status(datetime.now(timezone.utc), duration, True, 0)
+            dashboard.set_syncing(False)
             return True
 
+        dl_start = time.time()
         response = requests.get(config.ics_url, headers=HEADERS, timeout=30)
         response.raise_for_status()
         ics_text = response.text
+        dl_end = time.time()
+        ics_latency_ms = round((dl_end - dl_start) * 1000)
+        ics_download_size = len(ics_text)
         ics_hash = hashlib.sha256(ics_text.encode("utf-8")).hexdigest()
 
         if cached_hash == ics_hash:
             logger.info("No changes detected (hash match). Skipping sync.")
             if remote_etag:
                 state.set_ics_cache(ics_hash, remote_etag)
+            duration = time.time() - start_time
+            skipped = True
+            msg = "no changes (hash)"
+            session.record(True, duration, 0, 0, 0, True, ics_latency_ms, msg, ics_download_size)
+            if ics_download_size:
+                pass
+            health.update_status(datetime.now(timezone.utc), duration, True, 0)
+            dashboard.set_syncing(False)
             return True
 
         state.set_ics_cache(ics_hash, remote_etag)
@@ -101,30 +135,29 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
         if not to_add and not to_update and not to_delete:
             logger.info("Calendar is already in sync.")
             duration = time.time() - start_time
-            health.update_status(
-                datetime.now(timezone.utc),
-                duration,
-                True,
-                len(ics_uids),
-            )
+            skipped = True
+            msg = "already in sync"
+            session.record(True, duration, 0, 0, 0, True, ics_latency_ms, msg, ics_download_size)
             for uid, h in ics_uids.items():
                 state.upsert_event(uid, h)
+            health.update_status(datetime.now(timezone.utc), duration, True, len(ics_uids))
+            dashboard.set_event_count(len(ics_uids))
+            dashboard.set_syncing(False)
             return True
 
         if is_first_run and not to_delete:
             logger.info(
-                "First run detected: %d events in ICS. Registering state without re-adding to calendar.",
+                "First run detected: %d events in ICS. Registering state without re-adding.",
                 len(to_add),
             )
             for uid, h in ics_uids.items():
                 state.upsert_event(uid, h)
             duration = time.time() - start_time
-            health.update_status(
-                datetime.now(timezone.utc),
-                duration,
-                True,
-                len(ics_uids),
-            )
+            msg = f"first run, registered {len(to_add)} events"
+            session.record(True, duration, len(to_add), 0, 0, False, ics_latency_ms, msg, ics_download_size)
+            health.update_status(datetime.now(timezone.utc), duration, True, len(ics_uids))
+            dashboard.set_event_count(len(ics_uids))
+            dashboard.set_syncing(False)
             return True
 
         logger.info(
@@ -145,12 +178,10 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
         if not calendar:
             logger.error("Failed to find calendar")
             duration = time.time() - start_time
-            health.update_status(
-                datetime.now(timezone.utc),
-                duration,
-                False,
-                0,
-            )
+            msg = "calendar not found"
+            session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
+            health.update_status(datetime.now(timezone.utc), duration, False, 0)
+            dashboard.set_syncing(False)
             return False
 
         snapshot = state.snapshot()
@@ -162,19 +193,26 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
 
         try:
             logger.info("Phase 1: Adding %d events...", len(add_events))
+            s_a, e_a = 0, 0
             if add_events:
-                s, e = apply_adds(calendar, add_events)
-                logger.info("Added %d/%d events (%d errors)", s, len(add_events), e)
+                s_a, e_a = apply_adds(calendar, add_events)
+                logger.info("Added %d/%d events (%d errors)", s_a, len(add_events), e_a)
 
             logger.info("Phase 2: Updating %d events...", len(update_events))
+            s_u, e_u = 0, 0
             if update_events:
-                s, e = apply_updates(calendar, update_events)
-                logger.info("Updated %d/%d events (%d errors)", s, len(update_events), e)
+                s_u, e_u = apply_updates(calendar, update_events)
+                logger.info("Updated %d/%d events (%d errors)", s_u, len(update_events), e_u)
 
             logger.info("Phase 3: Deleting %d events...", len(delete_uids))
+            s_d, e_d = 0, 0
             if delete_uids:
-                s, e = apply_deletes(calendar, delete_uids)
-                logger.info("Deleted %d/%d events (%d errors)", s, len(delete_uids), e)
+                s_d, e_d = apply_deletes(calendar, delete_uids)
+                logger.info("Deleted %d/%d events (%d errors)", s_d, len(delete_uids), e_d)
+
+            added = s_a
+            updated = s_u
+            deleted = s_d
 
             for uid, h in ics_uids.items():
                 state.upsert_event(uid, h)
@@ -184,36 +222,31 @@ def sync_once(state: SyncState, health: HealthServer, config: Config) -> bool:
 
             total = len(ics_uids)
             duration = time.time() - start_time
+            msg = f"+{added} / ~{updated} / -{deleted}"
+            session.record(True, duration, added, updated, deleted, False, ics_latency_ms, msg, ics_download_size)
             logger.info("Sync completed in %.1fs. Total events: %d", duration, total)
-            health.update_status(
-                datetime.now(timezone.utc),
-                duration,
-                True,
-                total,
-            )
+            health.update_status(datetime.now(timezone.utc), duration, True, total)
+            dashboard.set_event_count(total)
+            dashboard.set_syncing(False)
             return True
 
         except Exception as exc:
             logger.error("Sync failed: %s. Rolling back state.", exc)
             state.restore_snapshot(snapshot)
             duration = time.time() - start_time
-            health.update_status(
-                datetime.now(timezone.utc),
-                duration,
-                False,
-                0,
-            )
+            msg = str(exc)[:80]
+            session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
+            health.update_status(datetime.now(timezone.utc), duration, False, 0)
+            dashboard.set_syncing(False)
             return False
 
     except Exception as exc:
         logger.error("Sync error: %s", exc)
         duration = time.time() - start_time
-        health.update_status(
-            datetime.now(timezone.utc),
-            duration,
-            False,
-            0,
-        )
+        msg = str(exc)[:80]
+        session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
+        health.update_status(datetime.now(timezone.utc), duration, False, 0)
+        dashboard.set_syncing(False)
         return False
 
 
@@ -233,6 +266,19 @@ def main():
     health.start()
     logger.info("Health endpoint on :8081")
 
+    session = SyncSession()
+    dashboard = DashboardServer(8082, health, session)
+    dashboard.update_config({
+        "ics_url": config.ics_url,
+        "baikal_url": config.baikal_url,
+        "baikal_user": config.baikal_user,
+        "baikal_pass": config.baikal_pass,
+        "sync_frequency": config.sync_frequency,
+        "calendar_id": os.environ.get("CALENDAR_ID", ""),
+    })
+    dashboard.start()
+    logger.info("Dashboard on :8082")
+
     backoff = 0
 
     def handle_signal(signum, frame):
@@ -243,7 +289,7 @@ def main():
     signal.signal(signal.SIGINT, handle_signal)
 
     while not shutdown_event.is_set():
-        success = sync_once(state, health, config)
+        success = sync_once(state, health, session, config, dashboard)
 
         if success:
             backoff = 0
@@ -253,11 +299,14 @@ def main():
             sleep_time = backoff * 60
             logger.info("Sync failed. Backing off %d minutes...", backoff)
 
+        dashboard.set_next_sync_in(sleep_time)
+        dashboard.set_backoff_min(backoff)
         logger.info("Next sync in %d seconds...", sleep_time)
         shutdown_event.wait(sleep_time)
 
     state.close()
     health.stop()
+    dashboard.stop()
     logger.info("Shutdown complete.")
 
 

From 2c05502553e5dba482f8357114ef3de9f011fbf4 Mon Sep 17 00:00:00 2001
From: Jose Lago <jose@lago.dev>
Date: Fri, 12 Jun 2026 10:06:20 +0200
Subject: [PATCH 7/7] fix: dashboard integration, remove port 8081, countdown
 persistence

---
 dashboard.py          | 39 +++++++++++++++++++++++++--------------
 docker-compose.yml    |  1 -
 static/dashboard.html | 18 ++++++++++++------
 sync_calendar.py      | 10 +++++++++-
 4 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/dashboard.py b/dashboard.py
index 11520f0..0f36efb 100644
--- a/dashboard.py
+++ b/dashboard.py
@@ -1,15 +1,20 @@
 import json
 import os
 import threading
+import time
 from http.server import HTTPServer, BaseHTTPRequestHandler
+from socketserver import ThreadingMixIn
 
-from health import HealthServer, SyncSession
+from health import SyncSession
+
+
+class ThreadingHTTPServer(ThreadingMixIn, HTTPServer):
+    daemon_threads = True
 
 
 class DashboardServer:
-    def __init__(self, port: int = 8082, health: HealthServer = None, session: SyncSession = None):
+    def __init__(self, port: int = 8082, session: SyncSession = None):
         self.port = port
-        self.health = health
         self.session = session
         self.server = None
         self.thread = None
@@ -19,11 +24,15 @@ class DashboardServer:
         self._event_count = 0
         self._backoff_min = 0
         self._config = {}
+        self._last_sync = None
+        self._last_duration = 0.0
+        self._last_success = None
+        self._last_latency_ms = 0
         self._base_dir = os.path.dirname(os.path.abspath(__file__))
 
     def start(self):
         handler = self._make_handler()
-        self.server = HTTPServer(("0.0.0.0", self.port), handler)
+        self.server = ThreadingHTTPServer(("0.0.0.0", self.port), handler)
         self.thread = threading.Thread(target=self.server.serve_forever, daemon=True)
         self.thread.start()
 
@@ -53,6 +62,13 @@ class DashboardServer:
         with self._lock:
             self._backoff_min = n
 
+    def set_last_sync(self, last_sync, duration: float, success: bool, latency_ms: int = 0):
+        with self._lock:
+            self._last_sync = last_sync
+            self._last_duration = duration
+            self._last_success = success
+            self._last_latency_ms = latency_ms
+
     def _get_status(self):
         with self._lock:
             syncing = self._syncing
@@ -60,15 +76,10 @@ class DashboardServer:
             event_count = self._event_count
             backoff_min = self._backoff_min
             config = dict(self._config)
-
-        last_sync = None
-        duration = 0.0
-        last_success = None
-        if self.health:
-            with self.health.lock:
-                last_sync = self.health.last_sync
-                duration = self.health.last_sync_duration
-                last_success = self.health.last_sync_success
+            last_sync = self._last_sync
+            duration = self._last_duration
+            last_success = self._last_success
+            latency_ms = self._last_latency_ms
 
         status = "idle"
         if syncing:
@@ -92,7 +103,7 @@ class DashboardServer:
             "status": status,
             "last_sync": last_sync.isoformat() if last_sync else None,
             "duration": duration,
-            "ics_latency_ms": ics_latency,
+            "ics_latency_ms": ics_latency if ics_latency else latency_ms,
             "event_count": event_count,
             "next_sync_in": next_sync_in,
             "session": session_data,
diff --git a/docker-compose.yml b/docker-compose.yml
index 0477a35..6670ff5 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -4,7 +4,6 @@ services:
     container_name: baikal-sync
     restart: always
     ports:
-      - "8081:8081"
       - "8082:8082"
     environment:
       - ICS_URL=${ICS_URL}
diff --git a/static/dashboard.html b/static/dashboard.html
index a5e34f4..2d31a41 100644
--- a/static/dashboard.html
+++ b/static/dashboard.html
@@ -333,6 +333,8 @@ header {
     lastPoll: null
   };
 
+  let countdownRemaining = 0;
+
   const $ = (sel) => document.querySelector(sel);
 
   function fmtBytes(b) {
@@ -502,7 +504,7 @@ header {
     $("#stackedLegend").innerHTML =
       '<div class="legend-item"><span class="legend-dot" style="background:var(--green)"></span>Added: ' + added + "</div>" +
       '<div class="legend-item"><span class="legend-dot" style="background:var(--blue)"></span>Updated: ' + updated + "</div>" +
-      '<div class="legend-item"><span class="legend-dot" style="background:var(--purple)"></span>Deleted: " + deleted + "</div>" +
+      '<div class="legend-item"><span class="legend-dot" style="background:var(--purple)"></span>Deleted: ' + deleted + "</div>" +
       '<div class="legend-item"><span class="legend-dot" style="background:var(--text-secondary)"></span>Skipped: ' + skipped + "</div>";
   }
 
@@ -673,14 +675,12 @@ header {
     const fill = $("#progressFill");
     if (!el || !fill) return;
 
-    let remaining = (state.data.next_sync_in || 0) - 1;
-    if (remaining < 0) remaining = 0;
-    el.textContent = fmtCountdown(remaining);
+    countdownRemaining = Math.max(0, countdownRemaining - 1);
+    el.textContent = fmtCountdown(countdownRemaining);
 
     const freq = state.data.config ? state.data.config.sync_frequency * 60 : 600;
-    const pct = freq > 0 ? Math.max(0, Math.min(100, ((freq - remaining) / freq) * 100)) : 100;
+    const pct = freq > 0 ? Math.max(0, Math.min(100, ((freq - countdownRemaining) / freq) * 100)) : 100;
     fill.style.width = pct + "%";
-    state.data.next_sync_in = remaining;
   }
 
   async function poll() {
@@ -689,6 +689,12 @@ header {
       if (!res.ok) throw new Error("HTTP " + res.status);
       state.data = await res.json();
       state.lastPoll = Date.now();
+      if (state.data.last_sync && state.data.config && state.data.config.sync_frequency) {
+        const syncEpoch = new Date(state.data.last_sync).getTime();
+        const freqSec = state.data.config.sync_frequency * 60;
+        const now = Date.now();
+        countdownRemaining = Math.max(0, Math.round(((syncEpoch + freqSec * 1000) - now) / 1000));
+      }
       renderStatusBar(state.data);
       renderStats(state.data);
       renderStackedBar(state.data);
diff --git a/sync_calendar.py b/sync_calendar.py
index 7ce64de..4d8c11e 100644
--- a/sync_calendar.py
+++ b/sync_calendar.py
@@ -89,6 +89,7 @@ def sync_once(
             msg = "no changes (ETag)"
             session.record(True, duration, 0, 0, 0, True, 0, msg)
             health.update_status(datetime.now(timezone.utc), duration, True, 0)
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, True, 0)
             dashboard.set_syncing(False)
             return True
 
@@ -112,6 +113,7 @@ def sync_once(
             if ics_download_size:
                 pass
             health.update_status(datetime.now(timezone.utc), duration, True, 0)
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, True, ics_latency_ms)
             dashboard.set_syncing(False)
             return True
 
@@ -141,6 +143,7 @@ def sync_once(
             for uid, h in ics_uids.items():
                 state.upsert_event(uid, h)
             health.update_status(datetime.now(timezone.utc), duration, True, len(ics_uids))
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, True, ics_latency_ms)
             dashboard.set_event_count(len(ics_uids))
             dashboard.set_syncing(False)
             return True
@@ -156,6 +159,7 @@ def sync_once(
             msg = f"first run, registered {len(to_add)} events"
             session.record(True, duration, len(to_add), 0, 0, False, ics_latency_ms, msg, ics_download_size)
             health.update_status(datetime.now(timezone.utc), duration, True, len(ics_uids))
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, True, ics_latency_ms)
             dashboard.set_event_count(len(ics_uids))
             dashboard.set_syncing(False)
             return True
@@ -181,6 +185,7 @@ def sync_once(
             msg = "calendar not found"
             session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
             health.update_status(datetime.now(timezone.utc), duration, False, 0)
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, False, ics_latency_ms)
             dashboard.set_syncing(False)
             return False
 
@@ -226,6 +231,7 @@ def sync_once(
             session.record(True, duration, added, updated, deleted, False, ics_latency_ms, msg, ics_download_size)
             logger.info("Sync completed in %.1fs. Total events: %d", duration, total)
             health.update_status(datetime.now(timezone.utc), duration, True, total)
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, True, ics_latency_ms)
             dashboard.set_event_count(total)
             dashboard.set_syncing(False)
             return True
@@ -237,6 +243,7 @@ def sync_once(
             msg = str(exc)[:80]
             session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
             health.update_status(datetime.now(timezone.utc), duration, False, 0)
+            dashboard.set_last_sync(datetime.now(timezone.utc), duration, False, ics_latency_ms)
             dashboard.set_syncing(False)
             return False
 
@@ -246,6 +253,7 @@ def sync_once(
         msg = str(exc)[:80]
         session.record(False, duration, 0, 0, 0, False, ics_latency_ms, msg, ics_download_size)
         health.update_status(datetime.now(timezone.utc), duration, False, 0)
+        dashboard.set_last_sync(datetime.now(timezone.utc), duration, False, ics_latency_ms)
         dashboard.set_syncing(False)
         return False
 
@@ -267,7 +275,7 @@ def main():
     logger.info("Health endpoint on :8081")
 
     session = SyncSession()
-    dashboard = DashboardServer(8082, health, session)
+    dashboard = DashboardServer(8082, session)
     dashboard.update_config({
         "ics_url": config.ics_url,
         "baikal_url": config.baikal_url,