Open way modify

lib/idx/protocol.ts

@@ -38,6 +38,7 @@ export class IndexProtocol {
         buf.writeBigUInt64LE(0n, 28);  // dataFileSize
         buf.writeUInt32LE(0, 36);  // latestSequence
         buf.writeUInt8(autoIncrementSequence ? 1 : 0, 40);  // autoIncrementSequence
+        buf.writeUInt32LE(0, 41);  // flags
         return buf;
     }
 
@@ -52,10 +53,15 @@ export class IndexProtocol {
             dataFileSize: buf.readBigUInt64LE(28),
             latestSequence: buf.readUInt32LE(36),
             autoIncrementSequence: buf.readUInt8(40) === 1,
-            reserved: buf.subarray(41, 64),
+            flags: buf.readUInt32LE(41),
+            reserved: buf.subarray(45, 64),
         };
     }
 
+    static writeFlags(buf: Buffer, flags: number): void {
+        buf.writeUInt32LE(flags, 41);
+    }
+
     static updateHeaderCounts(
         buf: Buffer,
         writtenCnt: number,

lib/idx/reader.ts

@@ -7,14 +7,14 @@ export class IndexReader {
     private buffer: Buffer | null = null;
     private header: IndexHeader | null = null;
 
-    readonly path: string;
+    private path: string | null = null;
 
-    constructor(path: string) {
-        this.path = path;
+    constructor() {
     }
 
-    open(): void {
+    open(idxFilePath: string): void {
         // Read entire file into buffer (simpler than mmap for read-only access)
+        this.path = idxFilePath;
         this.buffer = fs.readFileSync(this.path);
         this.header = IndexProtocol.readHeader(this.buffer);
     }
@@ -24,6 +24,11 @@ export class IndexReader {
         return this.header;
     }
 
+    getFlags(): number {
+        if (!this.header) throw new Error('Index file not opened');
+        return this.header.flags;
+    }
+
     getEntry(index: number): IndexEntry | null {
         if (!this.buffer || !this.header) throw new Error('Index file not opened');
         if (index < 0 || index >= this.header.entryCount) return null;

lib/idx/types.ts

@@ -9,6 +9,7 @@ export interface IndexHeader {
     dataFileSize: bigint;
     latestSequence: number;
     autoIncrementSequence: boolean;
+    flags: number;
     reserved: Buffer;
 }
 

lib/idx/writer.ts

@@ -151,6 +151,9 @@ export class IndexWriter {
             this.dataFileSize = newDataEnd;
         }
 
+        // Sync immediately after write
+        this.writeHeader();
+
         return true;
     }
 
@@ -158,7 +161,7 @@ export class IndexWriter {
         return this.latestSequence;
     }
 
-    syncHeader(): void {
+    writeHeader(): void {
         if (!this.headerBuf || this.fd === null) return;
 
         // Update header counts
@@ -177,7 +180,7 @@ export class IndexWriter {
         if (this.fd === null) return;
 
         // Sync header first
-        this.syncHeader();
+        this.writeHeader();
 
         // Sync all file changes to disk
         fs.fsyncSync(this.fd);
@@ -198,6 +201,16 @@ export class IndexWriter {
         this.entryBuf = null;
     }
 
+    writeFlags(flags: number): void {
+        if (!this.headerBuf || this.fd === null) {
+            throw new Error('Index file not opened');
+        }
+
+        IndexProtocol.writeFlags(this.headerBuf, flags);
+        fs.writeSync(this.fd, this.headerBuf, 41, 4, 41);
+        fs.fsyncSync(this.fd);
+    }
+
     getStats() {
         return {
             path: this.path,