Fix CalDAV/CardDAV multiget loading entire collections into memory

A REPORT multiget for a handful of resources previously listed the
whole calendar/address book (every row incl. ical_data/vcard) and
filtered by href in Rust with an O(N×M) substring scan. Large
collections paid full-table latency, RAM and DB CPU on every sync.

- Add find_events_by_ical_uids / get_contacts_by_uids through every
  layer (domain repo trait → PG repo → storage port/adapter → use case
  → handler) using one indexed `= ANY($2)` query, mirroring the
  existing single-UID lookups.
- Extract UIDs from multiget hrefs with a shared, tested
  uid_from_multiget_href helper (percent-decoding, case-insensitive
  extension strip, collection hrefs rejected). Exact UID matching also
  removes the false positives the old substring filter allowed.
- CalDAV PROPFIND single-event path now uses the existing indexed
  get_event_by_ical_uid instead of listing all events.
- Honour the already-documented limit/offset query params on
  GET /api/address-books/{id}/contacts: optional ListQuery fields
  thread through ContactUseCase::list_contacts to a paginated repo
  query. Omitted params keep returning the full book (frontend and
  DAV listing/sync paths unchanged).

https://claude.ai/code/session_0193Hff42gaA962wThxMGSd1

src/application/adapters/mod.rs

@@ -8,3 +8,91 @@ pub mod webdav_adapter;
 mod caldav_adapter_test;
 #[cfg(test)]
 mod carddav_adapter_test;
+
+/// Extract the resource UID from a DAV multiget `href`.
+///
+/// CalDAV/CardDAV multiget REPORTs address object resources by full href
+/// (e.g. `/caldav/{calendar_id}/{uid}.ics`, possibly with a username
+/// segment). The UID is the last path segment with the protocol
+/// `extension` (`.ics` / `.vcf`, matched case-insensitively) stripped,
+/// then percent-decoded — hrefs arrive in the XML body, so they have not
+/// gone through URL-path decoding, and clients may re-encode hrefs they
+/// previously read from the server.
+///
+/// Returns `None` for collection hrefs (empty last segment) or segments
+/// that are not valid UTF-8 after decoding.
+pub fn uid_from_multiget_href(href: &str, extension: &str) -> Option<String> {
+    // A trailing slash denotes a collection, not an object resource.
+    if href.ends_with('/') {
+        return None;
+    }
+    let segment = href.rsplit('/').next()?;
+
+    // Case-insensitive ASCII extension strip; the matched tail is ASCII,
+    // so the byte cut is guaranteed to land on a char boundary.
+    let bytes = segment.as_bytes();
+    let ext = extension.as_bytes();
+    let segment =
+        if bytes.len() >= ext.len() && bytes[bytes.len() - ext.len()..].eq_ignore_ascii_case(ext) {
+            &segment[..segment.len() - ext.len()]
+        } else {
+            segment
+        };
+
+    let decoded = percent_encoding::percent_decode_str(segment)
+        .decode_utf8()
+        .ok()?;
+    let uid = decoded.trim();
+    (!uid.is_empty()).then(|| uid.to_string())
+}
+
+#[cfg(test)]
+mod multiget_href_tests {
+    use super::uid_from_multiget_href;
+
+    #[test]
+    fn plain_caldav_href() {
+        assert_eq!(
+            uid_from_multiget_href("/caldav/abc-123/event-uid.ics", ".ics"),
+            Some("event-uid".to_string())
+        );
+    }
+
+    #[test]
+    fn href_with_username_prefix() {
+        assert_eq!(
+            uid_from_multiget_href("/carddav/alice/book-1/uid-42.vcf", ".vcf"),
+            Some("uid-42".to_string())
+        );
+    }
+
+    #[test]
+    fn uppercase_extension() {
+        assert_eq!(
+            uid_from_multiget_href("/caldav/abc/EVENT.ICS", ".ics"),
+            Some("EVENT".to_string())
+        );
+    }
+
+    #[test]
+    fn percent_encoded_uid() {
+        assert_eq!(
+            uid_from_multiget_href("/caldav/abc/uid%40example.com.ics", ".ics"),
+            Some("uid@example.com".to_string())
+        );
+    }
+
+    #[test]
+    fn missing_extension_uses_whole_segment() {
+        assert_eq!(
+            uid_from_multiget_href("/caldav/abc/bare-uid", ".ics"),
+            Some("bare-uid".to_string())
+        );
+    }
+
+    #[test]
+    fn collection_href_yields_none() {
+        assert_eq!(uid_from_multiget_href("/caldav/abc/", ".ics"), None);
+        assert_eq!(uid_from_multiget_href("", ".ics"), None);
+    }
+}

src/application/ports/calendar_ports.rs

@@ -95,6 +95,14 @@ pub trait CalendarStoragePort: Send + Sync + 'static {
         calendar_id: &str,
         ical_uid: &str,
     ) -> Result<Option<CalendarEventDto>, DomainError>;
+    /// Indexed batch lookup by iCalendar UID (`ical_uid = ANY(...)`) — the
+    /// CalDAV multiget REPORT must use this instead of listing the whole
+    /// calendar (every row + its `ical_data`) and filtering client-side.
+    async fn find_events_by_ical_uids(
+        &self,
+        calendar_id: &str,
+        ical_uids: &[String],
+    ) -> Result<Vec<CalendarEventDto>, DomainError>;
     async fn list_events_by_calendar(
         &self,
         calendar_id: &str,
@@ -197,6 +205,15 @@ pub trait CalendarUseCase: Send + Sync + 'static {
         ical_uid: &str,
         user_id: Uuid,
     ) -> Result<Option<CalendarEventDto>, DomainError>;
+    /// Resolve a batch of events by their iCalendar UIDs with a single
+    /// indexed query. UIDs without a matching event are silently absent
+    /// from the result (CalDAV multiget semantics).
+    async fn get_events_by_ical_uids(
+        &self,
+        calendar_id: &str,
+        ical_uids: &[String],
+        user_id: Uuid,
+    ) -> Result<Vec<CalendarEventDto>, DomainError>;
     async fn list_events(
         &self,
         calendar_id: &str,

src/application/ports/carddav_ports.rs

@@ -82,9 +82,25 @@ pub trait ContactUseCase: Send + Sync + 'static {
         uid: &str,
         user_id: Uuid,
     ) -> Result<Option<ContactDto>, DomainError>;
+    /// Resolve a batch of contacts by their vCard UIDs with a single
+    /// indexed query (`uid = ANY(...)`) — the CardDAV multiget REPORT
+    /// must use this instead of listing the whole address book and
+    /// filtering client-side. UIDs without a matching contact are
+    /// silently absent from the result.
+    async fn get_contacts_by_uids(
+        &self,
+        address_book_id: &str,
+        uids: &[String],
+        user_id: Uuid,
+    ) -> Result<Vec<ContactDto>, DomainError>;
+    /// List contacts in an address book. `limit`/`offset` bound the
+    /// result for paginated callers (REST API); `None` returns the full
+    /// book, which the CardDAV listing/sync paths rely on.
     async fn list_contacts(
         &self,
         address_book_id: &str,
+        limit: Option<i64>,
+        offset: Option<i64>,
         user_id: Uuid,
     ) -> Result<Vec<ContactDto>, DomainError>;
     async fn search_contacts(

src/application/services/calendar_service.rs

@@ -300,6 +300,32 @@ impl CalendarUseCase for CalendarService {
             .await
     }
 
+    async fn get_events_by_ical_uids(
+        &self,
+        calendar_id: &str,
+        ical_uids: &[String],
+        user_id: Uuid,
+    ) -> Result<Vec<CalendarEventDto>, DomainError> {
+        let has_access = self
+            .calendar_storage
+            .check_calendar_access(calendar_id, user_id)
+            .await?;
+        let calendar = self.calendar_storage.get_calendar(calendar_id).await?;
+        if !has_access && !calendar.is_public {
+            return Err(DomainError::new(
+                ErrorKind::AccessDenied,
+                "Calendar",
+                "You don't have permission to view events in this calendar",
+            ));
+        }
+        if ical_uids.is_empty() {
+            return Ok(Vec::new());
+        }
+        self.calendar_storage
+            .find_events_by_ical_uids(calendar_id, ical_uids)
+            .await
+    }
+
     async fn list_events(
         &self,
         calendar_id: &str,

src/application/services/contact_service.rs

@@ -796,9 +796,34 @@ impl ContactUseCase for ContactService {
         Ok(contact.map(ContactDto::from))
     }
 
+    async fn get_contacts_by_uids(
+        &self,
+        address_book_id: &str,
+        uids: &[String],
+        user_id: Uuid,
+    ) -> Result<Vec<ContactDto>, DomainError> {
+        let id = Uuid::parse_str(address_book_id)
+            .map_err(|_| DomainError::validation_error("Invalid address book ID format"))?;
+
+        // Check if user has access to the address book
+        self.check_address_book_access(&id, &user_id).await?;
+
+        if uids.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let contacts = self
+            .contact_repository
+            .get_contacts_by_uids(&id, uids)
+            .await?;
+        Ok(contacts.into_iter().map(ContactDto::from).collect())
+    }
+
     async fn list_contacts(
         &self,
         address_book_id: &str,
+        limit: Option<i64>,
+        offset: Option<i64>,
         user_id: Uuid,
     ) -> Result<Vec<ContactDto>, DomainError> {
         let id = Uuid::parse_str(address_book_id)
@@ -808,10 +833,17 @@ impl ContactUseCase for ContactService {
         self.check_address_book_access(&id, &user_id).await?;
 
         // Get contacts
-        let contacts = self
-            .contact_repository
-            .get_contacts_by_address_book(&id)
-            .await?;
+        let contacts = if limit.is_some() || offset.is_some() {
+            let limit = limit.unwrap_or(100);
+            let offset = offset.unwrap_or(0);
+            self.contact_repository
+                .get_contacts_by_address_book_paginated(&id, limit, offset)
+                .await?
+        } else {
+            self.contact_repository
+                .get_contacts_by_address_book(&id)
+                .await?
+        };
         let dtos = contacts.into_iter().map(ContactDto::from).collect();
 
         Ok(dtos)
@@ -1324,7 +1356,9 @@ impl StorageUseCase for ContactService {
                 let user_id = Uuid::parse_str(user_id)
                     .map_err(|_| DomainError::validation_error("Invalid user_id format"))?;
 
-                let result = self.list_contacts(address_book_id, user_id).await?;
+                let result = self
+                    .list_contacts(address_book_id, None, None, user_id)
+                    .await?;
                 Ok(serde_json::to_value(result).unwrap())
             }
             "search_contacts" => {