feat: configurable injection of js and css - #174

flutter_readium/ios/flutter_readium/Sources/flutter_readium/FlutterReadiumPlugin.swift:233

• The arguments coming from Dart are bridged as [[String: Any]] (with NSNull for nulls). Casting to [[String: Any?]] will often fail and silently fall back to [], making injection registration a no-op on iOS. Also, mapping via the force-casting initializer can crash; use a compactMap with the failable initializer.

    case "setCssInjections":
      let items = call.arguments as? [[String: Any?]] ?? []
      self.cssInjections = items.map { InjectionAsset(from: $0) }
      result(nil)
    case "setJavaScriptInjections":

flutter_readium/ios/flutter_readium/Sources/flutter_readium/FlutterReadiumPlugin.swift:43

• These new injection lists are stored and can be set over the method channel, but they are never read when building the WKWebView user scripts. As a result, the iOS implementation appears to accept injections without actually injecting them into EPUB resources.

  /// Extra CSS assets injected alongside the built-in helpers.
  var cssInjections: [InjectionAsset] = []

  /// Extra JavaScript assets injected alongside the built-in helpers.
  var javaScriptInjections: [InjectionAsset] = []

Previously missed (2) — in code that hasn't changed since the last review.

flutter_readium/android/src/main/kotlin/dk/nota/flutterreadium/PublicationChannel.kt:120

• Indentation for the setAudioRecoveryPolicy branch is inconsistent with the rest of this when and is likely to fail ktlint formatting checks.

             "setAudioRecoveryPolicy" -> {
                 val args = arguments as? Map<*, *>
                 ReadiumReader.audioRecoveryPolicy = AudioRecoveryPolicy.fromMap(args)
                 return Try.success(null)
             }

flutter_readium/android/src/main/kotlin/dk/nota/flutterreadium/ReadiumExtensions.kt:215

• <link> is a void element in HTML and should not be closed with </link>; this can break parsing in stricter EPUB/XHTML contexts. Prefer a self-closing tag.

                    injection.assetPath.endsWith(".css", ignoreCase = true) -> {
                        """<link rel="stylesheet" type="text/css" href="${injection.assetUrl}"></link>"""
                    }

flutter_readium/ios/flutter_readium/Sources/flutter_readium/FlutterReadiumPlugin.swift:237

• Same issue as setCssInjections: InjectionAsset(from:) is failable so map yields optionals and won’t assign to [InjectionAsset]. Use compactMap and a non-optional dictionary cast.

    case "setJavaScriptInjections":
      let items = call.arguments as? [[String: Any?]] ?? []
      self.javaScriptInjections = items.map { InjectionAsset(from: $0) }
      result(nil)

flutter_readium/android/src/main/kotlin/dk/nota/flutterreadium/PublicationChannel.kt:144

• Same issue as CSS injections: map["assetPath"] as String can throw and crash the plugin on malformed input. Prefer a safe cast and drop invalid items.

                        InjectionAsset(
                            assetPath = map["assetPath"] as String,
                            packageName = map["package"] as? String,
                        )
                    }

flutter_readium/ios/flutter_readium/Sources/flutter_readium/FlutterReadiumPlugin.swift:44

• cssInjections / javaScriptInjections are only assigned (via method calls) and never read anywhere in this file, so iOS never actually injects the configured assets. This makes the Dart API and changelog claim (“supported on iOS”) incorrect until the injections are wired into the EPUB resource/HTML injection pipeline during publication open.

  /// Extra CSS assets injected alongside the built-in helpers.
  var cssInjections: [InjectionAsset] = []

  /// Extra JavaScript assets injected alongside the built-in helpers.
  var javaScriptInjections: [InjectionAsset] = []

flutter_readium_platform_interface/lib/src/shared/injection_asset.dart:25

• There are extensive serialization round-trip tests in flutter_readium_platform_interface/test/models_test.dart, but this new model isn’t covered. Adding a small InjectionAsset toJson/fromJson round-trip test (and optionally a MethodChannel argument-shape test) would help prevent breaking the method-channel contract.

  @override
  Map<String, dynamic> toJson() => {}
    ..put('assetPath', assetPath)
    ..putOpt('package', package);