diff --git a/Resources/Info.plist b/Resources/Info.plist
index a859496..99479b9 100644
--- a/Resources/Info.plist
+++ b/Resources/Info.plist
@@ -19,9 +19,9 @@
     <key>CFBundlePackageType</key>
     <string>APPL</string>
     <key>CFBundleShortVersionString</key>
-    <string>1.0.4</string>
+    <string>1.0.5</string>
     <key>CFBundleVersion</key>
-    <string>17</string>
+    <string>18</string>
     <key>GlossSafariExtensionAvailable</key>
     <true/>
     <key>CFBundleDocumentTypes</key>
diff --git a/Sources/Gloss/BrowserExtensionFiles.swift b/Sources/Gloss/BrowserExtensionFiles.swift
index 37cd751..a2eb4cc 100644
--- a/Sources/Gloss/BrowserExtensionFiles.swift
+++ b/Sources/Gloss/BrowserExtensionFiles.swift
@@ -43,7 +43,9 @@ enum BrowserExtensionFiles {
 
         if fileManager.fileExists(atPath: destination.path) {
             let marker = destination.appendingPathComponent(markerName)
-            guard fileManager.fileExists(atPath: marker.path) else {
+            let isManaged = fileManager.fileExists(atPath: marker.path)
+            guard try isManaged || isRecognizableLegacyCopy(source: source, destination: destination)
+            else {
                 throw BrowserExtensionError.unmanagedDestination(destination.path)
             }
         }
@@ -73,6 +75,17 @@ enum BrowserExtensionFiles {
         return destination
     }
 
+    static func isRecognizableLegacyCopy(source: URL, destination: URL) throws -> Bool {
+        let sourceFiles = try relativeFiles(in: source).filter { $0 != markerName }
+        let destinationFiles = try relativeFiles(in: destination).filter { $0 != markerName }
+        guard sourceFiles == destinationFiles else { return false }
+
+        return FileManager.default.contentsEqual(
+            atPath: source.appendingPathComponent("manifest.json").path,
+            andPath: destination.appendingPathComponent("manifest.json").path
+        )
+    }
+
     static func synchronizeManagedCopy(source: URL, destination: URL) throws {
         let fileManager = FileManager.default
         let sourceFiles = try relativeFiles(in: source)
diff --git a/Tests/GlossAppTests/BrowserExtensionFilesTests.swift b/Tests/GlossAppTests/BrowserExtensionFilesTests.swift
index 008c898..bda9e0b 100644
--- a/Tests/GlossAppTests/BrowserExtensionFilesTests.swift
+++ b/Tests/GlossAppTests/BrowserExtensionFilesTests.swift
@@ -3,6 +3,48 @@ import XCTest
 @testable import Gloss
 
 final class BrowserExtensionFilesTests: XCTestCase {
+    func testRecognizesUnmarkedBundledCopyForMigration() throws {
+        let root = FileManager.default.temporaryDirectory
+            .appendingPathComponent("gloss-extension-migration-\(UUID().uuidString)", isDirectory: true)
+        let source = root.appendingPathComponent("source", isDirectory: true)
+        let destination = root.appendingPathComponent("destination", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: root) }
+
+        try FileManager.default.createDirectory(at: source, withIntermediateDirectories: true)
+        try FileManager.default.createDirectory(at: destination, withIntermediateDirectories: true)
+        let manifest = Data(#"{"name":"Gloss","version":"1.0.0"}"#.utf8)
+        try manifest.write(to: source.appendingPathComponent("manifest.json"))
+        try manifest.write(to: destination.appendingPathComponent("manifest.json"))
+        try Data("new".utf8).write(to: source.appendingPathComponent("background.js"))
+        try Data("old".utf8).write(to: destination.appendingPathComponent("background.js"))
+
+        XCTAssertTrue(
+            try BrowserExtensionFiles.isRecognizableLegacyCopy(
+                source: source,
+                destination: destination
+            )
+        )
+
+        try Data(#"{"name":"Other","version":"1.0.0"}"#.utf8).write(
+            to: destination.appendingPathComponent("manifest.json")
+        )
+        XCTAssertFalse(
+            try BrowserExtensionFiles.isRecognizableLegacyCopy(
+                source: source,
+                destination: destination
+            )
+        )
+
+        try manifest.write(to: destination.appendingPathComponent("manifest.json"))
+        try Data("foreign".utf8).write(to: destination.appendingPathComponent("extra.js"))
+        XCTAssertFalse(
+            try BrowserExtensionFiles.isRecognizableLegacyCopy(
+                source: source,
+                destination: destination
+            )
+        )
+    }
+
     func testSynchronizeManagedCopyUpdatesFilesWithoutReplacingDirectory() throws {
         let root = FileManager.default.temporaryDirectory
             .appendingPathComponent("gloss-extension-sync-\(UUID().uuidString)", isDirectory: true)
diff --git a/docs/release-notes/v1.0.5.md b/docs/release-notes/v1.0.5.md
new file mode 100644
index 0000000..70a49a5
--- /dev/null
+++ b/docs/release-notes/v1.0.5.md
@@ -0,0 +1,11 @@
+# Gloss 1.0.5
+
+Gloss 1.0.5 fixes browser extension setup for existing installations.
+
+## Browser extension
+
+- Migrates recognizable legacy extension directories that predate the Gloss management marker.
+- Preserves overwrite protection for unrelated or modified extension directories.
+- Restores the **Show Extension** action without requiring users to delete or reinstall the extension manually.
+
+Gloss 1.0.5 requires macOS 14 or newer.