diff --git a/examples/document_search.py b/examples/document_search.py
index 72d5bdc..b007bb3 100644
--- a/examples/document_search.py
+++ b/examples/document_search.py
@@ -74,7 +74,7 @@ def main():
     print(f"⏱️  Basic search time: {basic_time:.3f} seconds")
     print(">>> Basic search results <<<")
     for i, res in enumerate(results, 1):
-        print(f"  {i}. ID: {res['id']}, Score: {res['score']:.4f}, Text: '{res['text']}', Metadata: {res['metadata']}")
+        print(f"  {i}. ID: {res.id}, Score: {res.score:.4f}, Text: '{res.text}', Metadata: {res.metadata}")
 
     # --- 3. Recompute search demo ---
     print(f"\n[PHASE 3] Recompute search using embedding server...")
@@ -107,7 +107,7 @@ def main():
         print(f"⏱️  Recompute search time: {recompute_time:.3f} seconds")
         print(">>> Recompute search results <<<")
         for i, res in enumerate(recompute_results, 1):
-            print(f"  {i}. ID: {res['id']}, Score: {res['score']:.4f}, Text: '{res['text']}', Metadata: {res['metadata']}")
+            print(f"  {i}. ID: {res.id}, Score: {res.score:.4f}, Text: '{res.text}', Metadata: {res.metadata}")
         
         # Compare results
         print(f"\n--- Result comparison ---")
@@ -116,8 +116,8 @@ def main():
         
         print("\nBasic search vs Recompute results:")
         for i in range(min(len(results), len(recompute_results))):
-            basic_score = results[i]['score']
-            recompute_score = recompute_results[i]['score']
+            basic_score = results[i].score
+            recompute_score = recompute_results[i].score
             score_diff = abs(basic_score - recompute_score)
             print(f"  Position {i+1}: PQ={basic_score:.4f}, Recompute={recompute_score:.4f}, Difference={score_diff:.4f}")
         
diff --git a/packages/leann-backend-diskann/leann_backend_diskann/diskann_backend.py b/packages/leann-backend-diskann/leann_backend_diskann/diskann_backend.py
index 515560a..23ea745 100644
--- a/packages/leann-backend-diskann/leann_backend_diskann/diskann_backend.py
+++ b/packages/leann-backend-diskann/leann_backend_diskann/diskann_backend.py
@@ -3,7 +3,7 @@ import os
 import json
 import struct
 from pathlib import Path
-from typing import Dict, Any
+from typing import Dict, Any, List
 import contextlib
 import threading
 import time
@@ -11,6 +11,7 @@ import atexit
 import socket
 import subprocess
 import sys
+import pickle
 
 from leann.embedding_server_manager import EmbeddingServerManager
 from leann.registry import register_backend
@@ -19,13 +20,13 @@ from leann.interface import (
     LeannBackendBuilderInterface,
     LeannBackendSearcherInterface
 )
-from . import _diskannpy as diskannpy
-
-METRIC_MAP = {
-    "mips": diskannpy.Metric.INNER_PRODUCT,
-    "l2": diskannpy.Metric.L2,
-    "cosine": diskannpy.Metric.COSINE,
-}
+def _get_diskann_metrics():
+    from . import _diskannpy as diskannpy
+    return {
+        "mips": diskannpy.Metric.INNER_PRODUCT,
+        "l2": diskannpy.Metric.L2,
+        "cosine": diskannpy.Metric.COSINE,
+    }
 
 @contextlib.contextmanager
 def chdir(path):
@@ -67,27 +68,8 @@ class DiskannBuilder(LeannBackendBuilderInterface):
     def __init__(self, **kwargs):
         self.build_params = kwargs
 
-    def _generate_passages_file(self, index_dir: Path, index_prefix: str, **kwargs):
-        """Generate passages file for recompute mode, mirroring HNSW backend."""
-        try:
-            chunks = kwargs.get('chunks', [])
-            if not chunks:
-                print("INFO: No chunks data provided, skipping passages file generation for DiskANN.")
-                return
-            
-            passages_data = {str(node_id): chunk["text"] for node_id, chunk in enumerate(chunks)}
-            
-            passages_file = index_dir / f"{index_prefix}.passages.json"
-            with open(passages_file, 'w', encoding='utf-8') as f:
-                json.dump(passages_data, f, ensure_ascii=False, indent=2)
-            
-            print(f"✅ Generated passages file for recompute mode at '{passages_file}' ({len(passages_data)} passages)")
-            
-        except Exception as e:
-            print(f"💥 ERROR: Failed to generate passages file for DiskANN. Exception: {e}")
-            pass
 
-    def build(self, data: np.ndarray, index_path: str, **kwargs):
+    def build(self, data: np.ndarray, ids: List[str], index_path: str, **kwargs):
         path = Path(index_path)
         index_dir = path.parent
         index_prefix = path.stem
@@ -102,8 +84,15 @@ class DiskannBuilder(LeannBackendBuilderInterface):
         data_filename = f"{index_prefix}_data.bin"
         _write_vectors_to_bin(data, index_dir / data_filename)
 
+        # Create label map: integer -> string_id
+        label_map = {i: str_id for i, str_id in enumerate(ids)}
+        label_map_file = index_dir / "leann.labels.map"
+        with open(label_map_file, 'wb') as f:
+            pickle.dump(label_map, f)
+
         build_kwargs = {**self.build_params, **kwargs}
         metric_str = build_kwargs.get("distance_metric", "mips").lower()
+        METRIC_MAP = _get_diskann_metrics()
         metric_enum = METRIC_MAP.get(metric_str)
         if metric_enum is None:
             raise ValueError(f"Unsupported distance_metric '{metric_str}'.")
@@ -115,11 +104,11 @@ class DiskannBuilder(LeannBackendBuilderInterface):
         num_threads = build_kwargs.get("num_threads", 8)
         pq_disk_bytes = build_kwargs.get("pq_disk_bytes", 0)
         codebook_prefix = ""
-        is_recompute = build_kwargs.get("is_recompute", False)
 
         print(f"INFO: Building DiskANN index for {data.shape[0]} vectors with metric {metric_enum}...")
         
         try:
+            from . import _diskannpy as diskannpy
             with chdir(index_dir):
                 diskannpy.build_disk_float_index(
                     metric_enum,
@@ -134,8 +123,6 @@ class DiskannBuilder(LeannBackendBuilderInterface):
                     codebook_prefix
                 )
             print(f"✅ DiskANN index built successfully at '{index_dir / index_prefix}'")
-            if is_recompute:
-                self._generate_passages_file(index_dir, index_prefix, **build_kwargs)
         except Exception as e:
             print(f"💥 ERROR: DiskANN index build failed. Exception: {e}")
             raise
@@ -150,15 +137,6 @@ class DiskannSearcher(LeannBackendSearcherInterface):
         if not self.meta:
             raise ValueError("DiskannSearcher requires metadata from .meta.json.")
 
-        dimensions = self.meta.get("dimensions")
-        if not dimensions:
-            raise ValueError("Dimensions not found in Leann metadata.")
-        
-        self.distance_metric = self.meta.get("distance_metric", "mips").lower()
-        metric_enum = METRIC_MAP.get(self.distance_metric)
-        if metric_enum is None:
-            raise ValueError(f"Unsupported distance_metric '{self.distance_metric}'.")
-
         self.embedding_model = self.meta.get("embedding_model")
         if not self.embedding_model:
             print("WARNING: embedding_model not found in meta.json. Recompute will fail if attempted.")
@@ -167,11 +145,27 @@ class DiskannSearcher(LeannBackendSearcherInterface):
         self.index_dir = path.parent
         self.index_prefix = path.stem
         
+        # Load the label map
+        label_map_file = self.index_dir / "leann.labels.map"
+        if not label_map_file.exists():
+            raise FileNotFoundError(f"Label map file not found: {label_map_file}")
+        
+        with open(label_map_file, 'rb') as f:
+            self.label_map = pickle.load(f)
+        
+        # Extract parameters for DiskANN
+        distance_metric = kwargs.get("distance_metric", "mips").lower()
+        METRIC_MAP = _get_diskann_metrics()
+        metric_enum = METRIC_MAP.get(distance_metric)
+        if metric_enum is None:
+            raise ValueError(f"Unsupported distance_metric '{distance_metric}'.")
+        
         num_threads = kwargs.get("num_threads", 8)
         num_nodes_to_cache = kwargs.get("num_nodes_to_cache", 0)
         self.zmq_port = kwargs.get("zmq_port", 6666)
         
         try:
+            from . import _diskannpy as diskannpy
             full_index_prefix = str(self.index_dir / self.index_prefix)
             self._index = diskannpy.StaticDiskFloatIndex(
                 metric_enum, full_index_prefix, num_threads, num_nodes_to_cache, 1, self.zmq_port, "", ""
@@ -205,22 +199,18 @@ class DiskannSearcher(LeannBackendSearcherInterface):
 
             passages_file = kwargs.get("passages_file")
             if not passages_file:
-                potential_passages_file = self.index_dir / f"{self.index_prefix}.passages.json"
-                if potential_passages_file.exists():
-                    passages_file = str(potential_passages_file)
-                    print(f"INFO: Automatically found passages file: {passages_file}")
-
-            if not passages_file:
-                raise RuntimeError(
-                    f"Recompute mode is enabled, but no passages file was found. "
-                    f"A '{self.index_prefix}.passages.json' file should exist in the index directory "
-                    f"'{self.index_dir}'. Ensure you build the index with 'recompute=True'."
-                )
+                # Get the passages file path from meta.json
+                if 'passage_sources' in self.meta and self.meta['passage_sources']:
+                    passage_source = self.meta['passage_sources'][0]
+                    passages_file = passage_source['path']
+                    print(f"INFO: Found passages file from metadata: {passages_file}")
+                else:
+                    raise RuntimeError(f"FATAL: Recompute mode enabled but no passage_sources found in metadata.")
 
             server_started = self.embedding_server_manager.start_server(
                 port=self.zmq_port,
                 model_name=self.embedding_model,
-                distance_metric=self.distance_metric,
+                distance_metric=kwargs.get("distance_metric", "mips"),
                 passages_file=passages_file
             )
             
@@ -248,11 +238,23 @@ class DiskannSearcher(LeannBackendSearcherInterface):
                 batch_recompute,
                 global_pruning
             )
-            return {"labels": labels, "distances": distances}
+            
+            # Convert integer labels to string IDs
+            string_labels = []
+            for batch_labels in labels:
+                batch_string_labels = []
+                for int_label in batch_labels:
+                    if int_label in self.label_map:
+                        batch_string_labels.append(self.label_map[int_label])
+                    else:
+                        batch_string_labels.append(f"unknown_{int_label}")
+                string_labels.append(batch_string_labels)
+            
+            return {"labels": string_labels, "distances": distances}
         except Exception as e:
             print(f"💥 ERROR: DiskANN search failed. Exception: {e}")
             batch_size = query.shape[0]
-            return {"labels": np.full((batch_size, top_k), -1, dtype=np.int64), 
+            return {"labels": [[f"error_{i}" for i in range(top_k)] for _ in range(batch_size)], 
                    "distances": np.full((batch_size, top_k), float('inf'), dtype=np.float32)}
     
     def __del__(self):
diff --git a/packages/leann-backend-diskann/leann_backend_diskann/embedding_server.py b/packages/leann-backend-diskann/leann_backend_diskann/embedding_server.py
index a5e4329..ee2d4b2 100644
--- a/packages/leann-backend-diskann/leann_backend_diskann/embedding_server.py
+++ b/packages/leann-backend-diskann/leann_backend_diskann/embedding_server.py
@@ -41,21 +41,48 @@ class SimplePassageLoader:
 
 def load_passages_from_file(passages_file: str) -> SimplePassageLoader:
     """
-    Load passages from a JSON file
-    Expected format: {"passage_id": "passage_text", ...}
+    Load passages from a JSONL file with label map support
+    Expected format: {"id": "passage_id", "text": "passage_text", "metadata": {...}} (one per line)
     """
-    if not os.path.exists(passages_file):
-        print(f"Warning: Passages file {passages_file} not found. Using empty loader.")
-        return SimplePassageLoader()
+    from pathlib import Path
+    import pickle
     
-    try:
-        with open(passages_file, 'r', encoding='utf-8') as f:
-            passages_data = json.load(f)
-        print(f"Loaded {len(passages_data)} passages from {passages_file}")
-        return SimplePassageLoader(passages_data)
-    except Exception as e:
-        print(f"Error loading passages from {passages_file}: {e}")
-        return SimplePassageLoader()
+    if not os.path.exists(passages_file):
+        raise FileNotFoundError(f"Passages file {passages_file} not found.")
+    
+    if not passages_file.endswith('.jsonl'):
+        raise ValueError(f"Expected .jsonl file format, got: {passages_file}")
+    
+    # Load label map (int -> string_id)
+    passages_dir = Path(passages_file).parent
+    label_map_file = passages_dir / "leann.labels.map"
+    
+    label_map = {}
+    if label_map_file.exists():
+        with open(label_map_file, 'rb') as f:
+            label_map = pickle.load(f)
+        print(f"Loaded label map with {len(label_map)} entries")
+    else:
+        raise FileNotFoundError(f"Label map file not found: {label_map_file}")
+    
+    # Load passages by string ID
+    string_id_passages = {}
+    with open(passages_file, 'r', encoding='utf-8') as f:
+        for line in f:
+            if line.strip():
+                passage = json.loads(line)
+                string_id_passages[passage['id']] = passage['text']
+    
+    # Create int ID -> text mapping using label map
+    passages_data = {}
+    for int_id, string_id in label_map.items():
+        if string_id in string_id_passages:
+            passages_data[str(int_id)] = string_id_passages[string_id]
+        else:
+            print(f"WARNING: String ID {string_id} from label map not found in passages")
+    
+    print(f"Loaded {len(passages_data)} passages from JSONL file {passages_file} using label map")
+    return SimplePassageLoader(passages_data)
 
 def create_embedding_server_thread(
     zmq_port=5555,
diff --git a/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_backend.py b/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_backend.py
index dd678a7..bbf9cec 100644
--- a/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_backend.py
+++ b/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_backend.py
@@ -3,7 +3,7 @@ import os
 import json
 import struct
 from pathlib import Path
-from typing import Dict, Any
+from typing import Dict, Any, List
 import contextlib
 import threading
 import time
@@ -11,6 +11,7 @@ import atexit
 import socket
 import subprocess
 import sys
+import pickle
 
 from leann.embedding_server_manager import EmbeddingServerManager
 from .convert_to_csr import convert_hnsw_graph_to_csr
@@ -74,7 +75,7 @@ class HNSWBuilder(LeannBackendBuilderInterface):
         if self.is_recompute and not self.is_compact:
             raise ValueError("is_recompute requires is_compact=True for efficiency")
 
-    def build(self, data: np.ndarray, index_path: str, **kwargs):
+    def build(self, data: np.ndarray, ids: List[str], index_path: str, **kwargs):
         """Build HNSW index using FAISS"""
         from . import faiss
         
@@ -89,6 +90,12 @@ class HNSWBuilder(LeannBackendBuilderInterface):
         if not data.flags['C_CONTIGUOUS']:
             data = np.ascontiguousarray(data)
             
+        # Create label map: integer -> string_id
+        label_map = {i: str_id for i, str_id in enumerate(ids)}
+        label_map_file = index_dir / "leann.labels.map"
+        with open(label_map_file, 'wb') as f:
+            pickle.dump(label_map, f)
+            
         metric_str = self.distance_metric.lower()
         metric_enum = get_metric_map().get(metric_str)
         if metric_enum is None:
@@ -119,9 +126,6 @@ class HNSWBuilder(LeannBackendBuilderInterface):
             if self.is_compact:
                 self._convert_to_csr(index_file)
             
-            if self.is_recompute:
-                self._generate_passages_file(index_dir, index_prefix, **kwargs)
-            
         except Exception as e:
             print(f"💥 ERROR: HNSW index build failed. Exception: {e}")
             raise
@@ -155,30 +159,6 @@ class HNSWBuilder(LeannBackendBuilderInterface):
             print(f"💥 ERROR: CSR conversion failed. Exception: {e}")
             raise
 
-    def _generate_passages_file(self, index_dir: Path, index_prefix: str, **kwargs):
-        """Generate passages file for recompute mode"""
-        try:
-            chunks = kwargs.get('chunks', [])
-            if not chunks:
-                print("INFO: No chunks data provided, skipping passages file generation")
-                return
-            
-            # Generate node_id to text mapping
-            passages_data = {}
-            for node_id, chunk in enumerate(chunks):
-                passages_data[str(node_id)] = chunk["text"]
-            
-            # Save passages file
-            passages_file = index_dir / f"{index_prefix}.passages.json"
-            with open(passages_file, 'w', encoding='utf-8') as f:
-                json.dump(passages_data, f, ensure_ascii=False, indent=2)
-            
-            print(f"✅ Generated passages file for recompute mode at '{passages_file}' ({len(passages_data)} passages)")
-            
-        except Exception as e:
-            print(f"💥 ERROR: Failed to generate passages file. Exception: {e}")
-            # Don't raise - this is not critical for index building
-            pass
 
 class HNSWSearcher(LeannBackendSearcherInterface):
     def _get_index_storage_status(self, index_file: Path) -> tuple[bool, bool]:
@@ -282,6 +262,14 @@ class HNSWSearcher(LeannBackendSearcherInterface):
         self.index_dir = path.parent
         self.index_prefix = path.stem
         
+        # Load the label map
+        label_map_file = self.index_dir / "leann.labels.map"
+        if not label_map_file.exists():
+            raise FileNotFoundError(f"Label map file not found: {label_map_file}")
+        
+        with open(label_map_file, 'rb') as f:
+            self.label_map = pickle.load(f)
+        
         index_file = self.index_dir / f"{self.index_prefix}.index"
         if not index_file.exists():
             raise FileNotFoundError(f"HNSW index file not found at {index_file}")
@@ -336,12 +324,13 @@ class HNSWSearcher(LeannBackendSearcherInterface):
 
             passages_file = kwargs.get("passages_file")
             if not passages_file:
-                potential_passages_file = self.index_dir / f"{self.index_prefix}.passages.json"
-                if potential_passages_file.exists():
-                    passages_file = str(potential_passages_file)
-                    print(f"INFO: Automatically found passages file: {passages_file}")
+                # Get the passages file path from meta.json
+                if 'passage_sources' in self.meta and self.meta['passage_sources']:
+                    passage_source = self.meta['passage_sources'][0]
+                    passages_file = passage_source['path']
+                    print(f"INFO: Found passages file from metadata: {passages_file}")
                 else:
-                    raise RuntimeError(f"FATAL: Index is pruned but no passages file found.")
+                    raise RuntimeError(f"FATAL: Index is pruned but no passage_sources found in metadata.")
 
             zmq_port = kwargs.get("zmq_port", 5557)
             server_started = self.embedding_server_manager.start_server(
@@ -372,7 +361,18 @@ class HNSWSearcher(LeannBackendSearcherInterface):
             
             self._index.search(query.shape[0], faiss.swig_ptr(query), top_k, faiss.swig_ptr(distances), faiss.swig_ptr(labels), params)
             
-            return {"labels": labels, "distances": distances}
+            # Convert integer labels to string IDs
+            string_labels = []
+            for batch_labels in labels:
+                batch_string_labels = []
+                for int_label in batch_labels:
+                    if int_label in self.label_map:
+                        batch_string_labels.append(self.label_map[int_label])
+                    else:
+                        batch_string_labels.append(f"unknown_{int_label}")
+                string_labels.append(batch_string_labels)
+            
+            return {"labels": string_labels, "distances": distances}
             
         except Exception as e:
             print(f"💥 ERROR: HNSW search failed. Exception: {e}")
diff --git a/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_embedding_server.py b/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_embedding_server.py
index c548cae..c8cd358 100644
--- a/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_embedding_server.py
+++ b/packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_embedding_server.py
@@ -58,21 +58,46 @@ class SimplePassageLoader:
 
 def load_passages_from_file(passages_file: str) -> SimplePassageLoader:
     """
-    Load passages from a JSON file
-    Expected format: {"passage_id": "passage_text", ...}
+    Load passages from a JSONL file with label map support
+    Expected format: {"id": "passage_id", "text": "passage_text", "metadata": {...}} (one per line)
     """
     if not os.path.exists(passages_file):
-        print(f"Warning: Passages file {passages_file} not found. Using empty loader.")
-        return SimplePassageLoader()
+        raise FileNotFoundError(f"Passages file {passages_file} not found.")
     
-    try:
-        with open(passages_file, 'r', encoding='utf-8') as f:
-            passages_data = json.load(f)
-        print(f"Loaded {len(passages_data)} passages from {passages_file}")
-        return SimplePassageLoader(passages_data)
-    except Exception as e:
-        print(f"Error loading passages from {passages_file}: {e}")
-        return SimplePassageLoader()
+    if not passages_file.endswith('.jsonl'):
+        raise ValueError(f"Expected .jsonl file format, got: {passages_file}")
+    
+    # Load label map (int -> string_id)
+    passages_dir = Path(passages_file).parent
+    label_map_file = passages_dir / "leann.labels.map"
+    
+    label_map = {}
+    if label_map_file.exists():
+        import pickle
+        with open(label_map_file, 'rb') as f:
+            label_map = pickle.load(f)
+        print(f"Loaded label map with {len(label_map)} entries")
+    else:
+        raise FileNotFoundError(f"Label map file not found: {label_map_file}")
+    
+    # Load passages by string ID
+    string_id_passages = {}
+    with open(passages_file, 'r', encoding='utf-8') as f:
+        for line in f:
+            if line.strip():
+                passage = json.loads(line)
+                string_id_passages[passage['id']] = passage['text']
+    
+    # Create int ID -> text mapping using label map
+    passages_data = {}
+    for int_id, string_id in label_map.items():
+        if string_id in string_id_passages:
+            passages_data[str(int_id)] = string_id_passages[string_id]
+        else:
+            print(f"WARNING: String ID {string_id} from label map not found in passages")
+    
+    print(f"Loaded {len(passages_data)} passages from JSONL file {passages_file} using label map")
+    return SimplePassageLoader(passages_data)
 
 def create_hnsw_embedding_server(
     passages_file: Optional[str] = None,
diff --git a/packages/leann-core/src/leann/api.py b/packages/leann-core/src/leann/api.py
index ed6af41..d146bed 100644
--- a/packages/leann-core/src/leann/api.py
+++ b/packages/leann-core/src/leann/api.py
@@ -7,6 +7,8 @@ import json
 from pathlib import Path
 import openai
 from dataclasses import dataclass, field
+import uuid
+import pickle
 
 # --- Helper Functions for Embeddings ---
 
@@ -56,11 +58,45 @@ def _get_embedding_dimensions(model_name: str) -> int:
 @dataclass
 class SearchResult:
     """Represents a single search result."""
-    id: int
+    id: str
     score: float
     text: str
     metadata: Dict[str, Any] = field(default_factory=dict)
 
+
+class PassageManager:
+    """Manages passage data and lazy loading from JSONL files."""
+    
+    def __init__(self, passage_sources: List[Dict[str, Any]]):
+        self.offset_maps = {}
+        self.passage_files = {}
+        
+        for source in passage_sources:
+            if source["type"] == "jsonl":
+                passage_file = source["path"]
+                index_file = source["index_path"]
+                
+                if not os.path.exists(index_file):
+                    raise FileNotFoundError(f"Passage index file not found: {index_file}")
+                
+                with open(index_file, 'rb') as f:
+                    offset_map = pickle.load(f)
+                
+                self.offset_maps[passage_file] = offset_map
+                self.passage_files[passage_file] = passage_file
+    
+    def get_passage(self, passage_id: str) -> Dict[str, Any]:
+        """Lazy load a passage by ID."""
+        for passage_file, offset_map in self.offset_maps.items():
+            if passage_id in offset_map:
+                offset = offset_map[passage_id]
+                with open(passage_file, 'r', encoding='utf-8') as f:
+                    f.seek(offset)
+                    line = f.readline()
+                    return json.loads(line)
+        
+        raise KeyError(f"Passage ID not found: {passage_id}")
+
 # --- Core Classes ---
 
 class LeannBuilder:
@@ -82,7 +118,26 @@ class LeannBuilder:
         print(f"INFO: LeannBuilder initialized with '{backend_name}' backend.")
 
     def add_text(self, text: str, metadata: Optional[Dict[str, Any]] = None):
-        self.chunks.append({"text": text, "metadata": metadata or {}})
+        if metadata is None:
+            metadata = {}
+        
+        # Check if ID is provided in metadata
+        passage_id = metadata.get('id')
+        if passage_id is None:
+            passage_id = str(uuid.uuid4())
+        else:
+            # Validate uniqueness
+            existing_ids = {chunk['id'] for chunk in self.chunks}
+            if passage_id in existing_ids:
+                raise ValueError(f"Duplicate passage ID: {passage_id}")
+        
+        # Store the definitive ID with the chunk
+        chunk_data = {
+            "id": passage_id,
+            "text": text,
+            "metadata": metadata
+        }
+        self.chunks.append(chunk_data)
 
     def build_index(self, index_path: str):
         if not self.chunks:
@@ -92,28 +147,65 @@ class LeannBuilder:
             self.dimensions = _get_embedding_dimensions(self.embedding_model)
             print(f"INFO: Auto-detected dimensions for '{self.embedding_model}': {self.dimensions}")
 
+        path = Path(index_path)
+        index_dir = path.parent
+        index_name = path.name
+        
+        # Ensure the directory exists
+        index_dir.mkdir(parents=True, exist_ok=True)
+        
+        # Create the passages.jsonl file and offset index
+        passages_file = index_dir / f"{index_name}.passages.jsonl"
+        offset_file = index_dir / f"{index_name}.passages.idx"
+        
+        offset_map = {}
+        
+        with open(passages_file, 'w', encoding='utf-8') as f:
+            for chunk in self.chunks:
+                offset = f.tell()
+                passage_data = {
+                    "id": chunk["id"],
+                    "text": chunk["text"],
+                    "metadata": chunk["metadata"]
+                }
+                json.dump(passage_data, f, ensure_ascii=False)
+                f.write('\n')
+                offset_map[chunk["id"]] = offset
+        
+        # Save the offset map
+        with open(offset_file, 'wb') as f:
+            pickle.dump(offset_map, f)
+        
+        # Compute embeddings
         texts_to_embed = [c["text"] for c in self.chunks]
         embeddings = _compute_embeddings(texts_to_embed, self.embedding_model)
-
+        
+        # Extract string IDs for the backend
+        string_ids = [chunk["id"] for chunk in self.chunks]
+        
+        # Build the vector index
         current_backend_kwargs = self.backend_kwargs.copy()
         current_backend_kwargs['dimensions'] = self.dimensions
         builder_instance = self.backend_factory.builder(**current_backend_kwargs)
         
-        build_kwargs = current_backend_kwargs.copy()
-        build_kwargs['chunks'] = self.chunks
-        builder_instance.build(embeddings, index_path, **build_kwargs)
+        builder_instance.build(embeddings, string_ids, index_path, **current_backend_kwargs)
 
-        index_dir = Path(index_path).parent
-        leann_meta_path = index_dir / f"{Path(index_path).name}.meta.json"
+        # Create the lightweight meta.json file
+        leann_meta_path = index_dir / f"{index_name}.meta.json"
         
         meta_data = {
-            "version": "0.1.0",
+            "version": "1.0",
             "backend_name": self.backend_name,
             "embedding_model": self.embedding_model,
             "dimensions": self.dimensions,
             "backend_kwargs": self.backend_kwargs,
-            "num_chunks": len(self.chunks),
-            "chunks": self.chunks,
+            "passage_sources": [
+                {
+                    "type": "jsonl",
+                    "path": str(passages_file),
+                    "index_path": str(offset_file)
+                }
+            ]
         }
         with open(leann_meta_path, 'w', encoding='utf-8') as f:
             json.dump(meta_data, f, indent=2)
@@ -136,14 +228,16 @@ class LeannSearcher:
         backend_name = self.meta_data['backend_name']
         self.embedding_model = self.meta_data['embedding_model']
         
+        # Initialize the passage manager
+        passage_sources = self.meta_data.get('passage_sources', [])
+        self.passage_manager = PassageManager(passage_sources)
+        
         backend_factory = BACKEND_REGISTRY.get(backend_name)
         if backend_factory is None:
             raise ValueError(f"Backend '{backend_name}' (from index file) not found or not registered.")
 
-        final_kwargs = self.meta_data.get("backend_kwargs", {})
-        final_kwargs.update(backend_kwargs)
-        if 'dimensions' not in final_kwargs:
-            final_kwargs['dimensions'] = self.meta_data.get('dimensions')
+        final_kwargs = backend_kwargs.copy()
+        final_kwargs['meta'] = self.meta_data
 
         self.backend_impl = backend_factory.searcher(index_path, **final_kwargs)
         print(f"INFO: LeannSearcher initialized with '{backend_name}' backend using index '{index_path}'.")
@@ -155,15 +249,17 @@ class LeannSearcher:
         results = self.backend_impl.search(query_embedding, top_k, **search_kwargs)
         
         enriched_results = []
-        for label, dist in zip(results['labels'][0], results['distances'][0]):
-            if label < len(self.meta_data['chunks']):
-                chunk_info = self.meta_data['chunks'][label]
+        for string_id, dist in zip(results['labels'][0], results['distances'][0]):
+            try:
+                passage_data = self.passage_manager.get_passage(string_id)
                 enriched_results.append(SearchResult(
-                    id=label,
+                    id=string_id,
                     score=dist,
-                    text=chunk_info['text'],
-                    metadata=chunk_info.get('metadata', {})
+                    text=passage_data['text'],
+                    metadata=passage_data.get('metadata', {})
                 ))
+            except KeyError:
+                print(f"WARNING: Passage ID '{string_id}' not found in passage files")
         return enriched_results