diff --git a/src/SuwayomiMover.py b/src/SuwayomiMover.py
index ff514ef..8dd2643 100644
--- a/src/SuwayomiMover.py
+++ b/src/SuwayomiMover.py
@@ -43,6 +43,7 @@ Dependencies
 
 from __future__ import annotations
 
+import json
 import re
 import shutil
 import xml.etree.ElementTree as ET
@@ -64,6 +65,62 @@ from MangaBakaRateLimit import apply_to_session as _apply_mangabaka_rate_limit
 _IMAGE_EXTS = {".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp", ".avif"}
 _CHAPTER_RE = re.compile(r'[Cc]hapter\s+(\d+(?:\.\d+)?)')
 
+# JSON file written into each Kavita series folder, listing every chapter
+# already moved.  Avoids opening CBZ archives to determine what is present.
+# Absence is interpreted as "folder empty" (per spec), not "scan the folder".
+_CHAPTER_INDEX_FILENAME = "chapter_index.json"
+
+
+def _normalise_volume_value(value):
+    """
+    Normalises a volume identifier for storage in chapter_index.json.
+
+    Returns int when the value is a whole number, float for fractional
+    volumes, None when missing.  Mirrors how the user wants volumes
+    rendered (``"volume": 1`` rather than ``"volume": "1"``).
+    """
+    if value is None:
+        return None
+    text = str(value).strip()
+    if not text:
+        return None
+    try:
+        f = float(text)
+        return int(f) if f.is_integer() else f
+    except (TypeError, ValueError):
+        return text
+
+
+def _load_chapter_index(dest_series: Path) -> dict:
+    """
+    Reads chapter_index.json from a Kavita series folder.
+
+    Returns ``{"chapter": {}}`` when the file is missing or unreadable —
+    per the project spec, absence means "no chapters are present yet".
+    """
+    path = dest_series / _CHAPTER_INDEX_FILENAME
+    if not path.is_file():
+        return {"chapter": {}}
+    try:
+        with path.open("r", encoding="utf-8") as f:
+            data = json.load(f)
+    except (OSError, json.JSONDecodeError) as exc:
+        print(f"  [warn] chapter_index unreadable ({path.name}): {exc} — "
+              f"treating folder as empty")
+        return {"chapter": {}}
+    if not isinstance(data, dict) or not isinstance(data.get("chapter"), dict):
+        return {"chapter": {}}
+    return data
+
+
+def _save_chapter_index(dest_series: Path, index: dict) -> None:
+    """Writes chapter_index.json atomically into a Kavita series folder."""
+    path = dest_series / _CHAPTER_INDEX_FILENAME
+    tmp = path.with_suffix(path.suffix + ".tmp")
+    with tmp.open("w", encoding="utf-8") as f:
+        json.dump(index, f, ensure_ascii=False, indent=2)
+    tmp.replace(path)
+
 # Parenthetical source labels that Suwayomi appends to series names.
 # These are not part of the actual title and confuse MangaBaka searches.
 _SOURCE_LABEL_RE = re.compile(
@@ -509,13 +566,38 @@ class SuwayomiMover:
         dest_series = self._dst / _sanitize_dirname(mangabaka_title)
         dest_series.mkdir(parents=True, exist_ok=True)
 
+        # Skip chapters that have already been moved to Kavita.  The index
+        # file in the destination folder is the authoritative source — we
+        # never open CBZ archives or stat them individually.
+        chapter_index = _load_chapter_index(dest_series)
+        already_moved = chapter_index["chapter"]
+        skipped: list[tuple[Path, str]] = []
+        pending:  list[tuple[Path, dict, str]] = []
+        for item in chapter_items:
+            chapter_dir, _fields, chapter_num = item
+            if chapter_num in already_moved:
+                skipped.append((chapter_dir, chapter_num))
+            else:
+                pending.append(item)
+
+        for chapter_dir, chapter_num in skipped:
+            print(f"  Chapter {chapter_num}: skip (already in Kavita)")
+            if self._delete_source:
+                shutil.rmtree(chapter_dir, ignore_errors=True)
+
         chapter_results: list[dict] = []
-        for chapter_dir, _fields, chapter_num in chapter_items:
+        for chapter_dir, _fields, chapter_num in pending:
             result = self._process_chapter(
                 builder, chapter_num, chapter_dir, dest_series)
             chapter_results.append(result)
             status = "ok" if result["ok"] else f"ERROR: {result.get('error')}"
             print(f"  Chapter {chapter_num}: {status}")
+            if result["ok"]:
+                already_moved[chapter_num] = {
+                    "volume":      _normalise_volume_value(result.get("volume")),
+                    "archiveName": Path(result["cbz"]).name,
+                }
+                _save_chapter_index(dest_series, chapter_index)
 
         # Sync Kavita persons once per series.
         # Both MAL and AniList IDs come from MangaBaka's source map;
@@ -557,11 +639,19 @@ class SuwayomiMover:
         try:
             builder.chapter = chapter_num
             builder.add_pages_from_folder(chapter_dir, cover_filename="000")
+            # Resolving the volume here piggy-backs on caches already warmed
+            # by add_pages_from_folder, so it's effectively free.  Used by
+            # the chapter index in the Kavita destination folder.
+            try:
+                volume = builder._determine_volume()
+            except Exception:
+                volume = None
             builder.save_xml(chapter_dir)
             _pack_to_cbz(chapter_dir, cbz_path)
             if self._delete_source:
                 shutil.rmtree(chapter_dir)
-            return {"chapter": chapter_num, "cbz": str(cbz_path), "ok": True}
+            return {"chapter": chapter_num, "cbz": str(cbz_path),
+                    "ok": True, "volume": volume}
         except Exception as exc:
             return {"chapter": chapter_num, "cbz": str(cbz_path),
                     "ok": False, "error": str(exc)}