cursor behavior fixes

crates/service/web/storyteller_web/src/http_server/endpoints/folders/folder/list_folders_handler.rs

@@ -70,9 +70,16 @@ pub async fn list_folders_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/endpoints/folders/media_files/list_folder_media_files_handler.rs

@@ -163,9 +163,16 @@ pub async fn list_folder_media_files_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/endpoints/folders/subfolder/list_subfolders_handler.rs

@@ -93,9 +93,16 @@ pub async fn list_subfolders_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/staff_audit_logs/moderator_list_staff_audit_logs_handler.rs

@@ -98,10 +98,16 @@ pub async fn moderator_list_staff_audit_logs_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = records.last().map(|last| {
-    server_state.opaque_cursors
-        .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if records.len() == limit as usize {
+    records.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let audit_logs = records.into_iter().map(|r| {
     StaffAuditLogResponse {

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/user_emails/moderator_list_email_address_changes_for_user_handler.rs

@@ -140,10 +140,16 @@ pub async fn moderator_list_email_address_changes_for_user_handler(
   })?;
 
   // 5. Encode the next-page cursor from the last id, if there was one.
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors
-      .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let changes = rows.into_iter().map(to_response_item).collect();
 

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/user_referrals/moderator_list_global_user_referrals_handler.rs

@@ -64,10 +64,16 @@ pub async fn moderator_list_global_user_referrals_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = records.last().map(|last| {
-    server_state.opaque_cursors
-      .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if records.len() == limit as usize {
+    records.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let referrals = records.into_iter().map(|r| {
     UserReferralResponse {

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/user_referrals/moderator_list_user_referrals_for_user_handler.rs

@@ -72,10 +72,16 @@ pub async fn moderator_list_user_referrals_for_user_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = records.last().map(|last| {
-    server_state.opaque_cursors
-      .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if records.len() == limit as usize {
+    records.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let referrals = records.into_iter().map(|r| {
     UserReferralResponse {

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/user_sessions/moderator_list_user_session_impersonation_requests_for_user_handler.rs

@@ -104,10 +104,16 @@ pub async fn moderator_list_user_session_impersonation_requests_for_user_handler
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = records.last().map(|last| {
-    server_state.opaque_cursors
-        .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if records.len() == limit as usize {
+    records.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let impersonation_requests = records.into_iter().map(|r| {
     UserImpersonationRequestResponse {

crates/service/web/storyteller_web/src/http_server/endpoints/moderation/user_sessions/moderator_list_user_session_impersonation_requests_handler.rs

@@ -97,10 +97,16 @@ pub async fn moderator_list_user_session_impersonation_requests_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = records.last().map(|last| {
-    server_state.opaque_cursors
-        .encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if records.len() == limit as usize {
+    records.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let impersonation_requests = records.into_iter().map(|r| {
     AllImpersonationRequestResponse {

crates/service/web/storyteller_web/src/http_server/endpoints/tags/list_media_files_with_tag_handler.rs

@@ -101,9 +101,16 @@ pub async fn list_media_files_with_tag_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/endpoints/tags/list_tagged_media_files_handler.rs

@@ -77,9 +77,16 @@ pub async fn list_tagged_media_files_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/endpoints/tags/list_tags_handler.rs

@@ -62,9 +62,16 @@ pub async fn list_tags_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.id))
+        .transpose()?
+  } else {
+    None
+  };
 
   Ok(Json(ListTagsSuccessResponse {
     success: true,

crates/service/web/storyteller_web/src/http_server/endpoints/tags/list_untagged_media_files_handler.rs

@@ -77,9 +77,16 @@ pub async fn list_untagged_media_files_handler(
     CommonWebError::from_error(err)
   })?;
 
-  let maybe_cursor = rows.last().map(|last| {
-    server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id)
-  }).transpose()?;
+  // Only hand out a next-page cursor when this page was full. A short page
+  // means the list is exhausted, and emitting a cursor anyway would make
+  // clients fetch one guaranteed-empty trailing page.
+  let maybe_cursor = if rows.len() == limit as usize {
+    rows.last()
+        .map(|last| server_state.opaque_cursors.encode_last_id_cursor(CURSOR_NAME, last.media_file_id))
+        .transpose()?
+  } else {
+    None
+  };
 
   let media_domain = get_media_domain(&http_request);
   let server_environment = server_state.server_environment;

crates/service/web/storyteller_web/src/http_server/web_utils/web_opaque_cursor_encoder_v2.rs

@@ -26,7 +26,7 @@ impl WebOpaqueCursorEncoderV2 {
     self.encoder.encode_last_id_cursor(name, id)
         .map_err(|err| {
           warn!("Failed to encode pagination cursor for {:?}: {:?}", name, err);
-          CommonWebError::server_error_with_message("Failed to encode cursor")
+          CommonWebError::from_error(err)
         })
   }