From c328a798f7b5f19999fd0274387b0aab6f3360dc Mon Sep 17 00:00:00 2001 From: jie65535 Date: Mon, 27 Jul 2026 14:01:12 +0800 Subject: [PATCH] tools: resolve images by short references --- src/main/kotlin/ImageIndex.kt | 29 ++++++++ src/main/kotlin/JChatGPT.kt | 72 +++++++++++++------- src/main/kotlin/tools/ImageAgent.kt | 22 ++++-- src/main/kotlin/tools/SearchChatHistory.kt | 10 +-- src/main/kotlin/tools/VisualAgent.kt | 35 +++++++--- src/main/kotlin/tools/VisualImageResolver.kt | 37 +++++++++- src/test/kotlin/ImageIndexTest.kt | 32 +++++++++ 7 files changed, 187 insertions(+), 50 deletions(-) create mode 100644 src/main/kotlin/ImageIndex.kt create mode 100644 src/test/kotlin/ImageIndexTest.kt diff --git a/src/main/kotlin/ImageIndex.kt b/src/main/kotlin/ImageIndex.kt new file mode 100644 index 0000000..3e50d6b --- /dev/null +++ b/src/main/kotlin/ImageIndex.kt @@ -0,0 +1,29 @@ +package top.jie65535.mirai + +/** + * 会话内图片短索引：向 LLM 暴露递增整数，内部保留从原消息图片取得的精确 URL。 + * 同一 imageId 重复出现在上下文中时复用原编号，并用最新取得的 URL 刷新映射。 + */ +internal class ImageIndex { + private val imageUrlByIndex = LinkedHashMap() + private val indexByImageId = HashMap() + private var counter = 0 + + @Synchronized + fun add(imageId: String, imageUrl: String): Int { + require(imageId.isNotBlank()) { "图片ID不能为空" } + require(imageUrl.isNotBlank()) { "图片URL不能为空" } + indexByImageId[imageId]?.let { index -> + imageUrlByIndex[index] = imageUrl + return index + } + + val index = ++counter + imageUrlByIndex[index] = imageUrl + indexByImageId[imageId] = index + return index + } + + @Synchronized + fun getUrl(index: Int): String? = imageUrlByIndex[index] +} diff --git a/src/main/kotlin/JChatGPT.kt b/src/main/kotlin/JChatGPT.kt index 59b1bf8..2e0e88d 100644 --- a/src/main/kotlin/JChatGPT.kt +++ b/src/main/kotlin/JChatGPT.kt @@ -144,7 +144,8 @@ object JChatGPT : KotlinPlugin( private data class ConversationCache( val history: MutableList, val lastActivityAt: Int, - val replyIndex: ReplyIndex + val replyIndex: ReplyIndex, + val imageIndex: ImageIndex, ) { fun isExpired(ttlSeconds: Int): Boolean { return OffsetDateTime.now().toEpochSecond().toInt() - lastActivityAt > ttlSeconds @@ -182,10 +183,21 @@ object JChatGPT : KotlinPlugin( /** 各会话的回复索引，startChat 开始时重建，结束时清理 */ private val replyIndexMap = ConcurrentMap() + /** 各会话的图片索引，生命周期与回复索引、对话缓存一致。 */ + private val imageIndexMap = ConcurrentMap() + /** 供发言工具按编号查找被引用的历史消息 */ internal fun lookupReplyTarget(subjectId: Long, index: Int): MessageRecord? = replyIndexMap[subjectId]?.get(index) + /** 将从原消息图片取得的精确 URL 登记为短编号，供历史搜索等工具追加图片引用。 */ + internal fun registerImage(subjectId: Long, imageId: String, imageUrl: String): Int? = + imageIndexMap[subjectId]?.add(imageId, imageUrl) + + /** 按会话内短编号获取原消息解析出的 URL，避免根据 imageId 二次构造和查询。 */ + internal fun lookupImageUrl(subjectId: Long, index: Int): String? = + imageIndexMap[subjectId]?.getUrl(index) + private val shortTimeFormatter = DateTimeFormatter.ofPattern("HH:mm") .withZone(ZoneOffset.systemDefault()) @@ -339,8 +351,9 @@ object JChatGPT : KotlinPlugin( * @return 如果未获取到则返回空字符串 */ private fun getHistory(event: MessageEvent): String { + val imageIndex = imageIndexMap.getOrPut(event.subject.id) { ImageIndex() } if (!includeHistory) { - return event.message.content + return formatRecordContent(event.message, event.subject, imageIndex) } val now = OffsetDateTime.now() // 一段时间内的消息 @@ -378,6 +391,7 @@ object JChatGPT : KotlinPlugin( var lastTime = 0L // 本轮回复索引，逐条登记消息编号供 [n] 引用 val replyIndex = replyIndexMap.getOrPut(event.subject.id) { ReplyIndex() } + val imageIndex = imageIndexMap.getOrPut(event.subject.id) { ImageIndex() } if (event is GroupMessageEvent) { if (PluginConfig.enableFavorabilitySystem) { val knownUsers = history.asSequence() @@ -404,12 +418,12 @@ object JChatGPT : KotlinPlugin( } } - historyText.appendLine("## 近期群消息（更早已隐藏，行首[n]为消息编号，可用于引用回复）") + historyText.appendLine("## 近期群消息（更早已隐藏，行首[n]为消息编号；正文[图片n]/[表情包n]中的n为识图或图片编辑编号）") for (record in history) { // 同一人发言不要反复出现这人的名字，减少上下文 val showSender = lastId != record.fromId val showTime = showSender || record.time.toLong() - lastTime > CONTINUATION_TIME_GAP_SECONDS - appendGroupMessageRecord(historyText, record, event, replyIndex, showSender, showTime) + appendGroupMessageRecord(historyText, record, event, replyIndex, imageIndex, showSender, showTime) lastId = record.fromId lastTime = record.time.toLong() } @@ -428,12 +442,12 @@ object JChatGPT : KotlinPlugin( } } - historyText.appendLine("## 近期对话（更早已隐藏，行首[n]为消息编号，可用于引用回复）") + historyText.appendLine("## 近期对话（更早已隐藏，行首[n]为消息编号；正文[图片n]/[表情包n]中的n为识图或图片编辑编号）") for (record in history) { // 同一人发言不要反复出现这人的名字，减少上下文 val showSender = lastId != record.fromId val showTime = showSender || record.time.toLong() - lastTime > CONTINUATION_TIME_GAP_SECONDS - appendMessageRecord(historyText, record, event, replyIndex, showSender, showTime) + appendMessageRecord(historyText, record, event, replyIndex, imageIndex, showSender, showTime) lastId = record.fromId lastTime = record.time.toLong() } @@ -448,11 +462,12 @@ object JChatGPT : KotlinPlugin( * @param record 群消息记录 * @param event 群消息事件 */ - fun appendGroupMessageRecord( + private fun appendGroupMessageRecord( historyText: StringBuilder, record: MessageRecord, event: GroupMessageEvent, replyIndex: ReplyIndex, + imageIndex: ImageIndex, showSender: Boolean, showTime: Boolean, ) { @@ -481,10 +496,10 @@ object JChatGPT : KotlinPlugin( // 引用：用编号指针替代内联原文，避免被误认为是本人发言 recordMessage[QuoteReply.Key]?.let { - appendQuoteMarker(historyText, it, event.subject, replyIndex) + appendQuoteMarker(historyText, it, event.subject, replyIndex, imageIndex) } - historyText.appendLine(formatRecordContent(recordMessage, event.subject)) + historyText.appendLine(formatRecordContent(recordMessage, event.subject, imageIndex)) } /** @@ -494,7 +509,8 @@ object JChatGPT : KotlinPlugin( sb: StringBuilder, quote: QuoteReply, contact: Contact, - replyIndex: ReplyIndex + replyIndex: ReplyIndex, + imageIndex: ImageIndex, ) { val srcIds = quote.source.ids.joinToString(",") val idx = replyIndex.indexOfIds(srcIds) @@ -507,7 +523,7 @@ object JChatGPT : KotlinPlugin( quote.source.fromId.toString() } val snippet = quote.source.originalMessage - .joinToString("", transform = ::singleMessageToText) + .joinToString("") { singleMessageToText(it, imageIndex) } .replace("\n", " ") .let { if (it.length > 20) it.take(20) + "…" else it } sb.append("↩(").append(author).append(":\"").append(snippet).append("\") ") @@ -517,13 +533,13 @@ object JChatGPT : KotlinPlugin( /** * 序列化消息正文（剔除引用/源元数据，@显示为名称，转发折叠）。 */ - private fun formatRecordContent(chain: MessageChain, contact: Contact): String = + private fun formatRecordContent(chain: MessageChain, contact: Contact, imageIndex: ImageIndex): String = chain.asSequence() .filterNot { it is QuoteReply || it is MessageSource } .joinToString("") { when (it) { is At -> if (contact is Group) it.getDisplay(contact) else it.content - else -> singleMessageToText(it) + else -> singleMessageToText(it, imageIndex) } } @@ -542,11 +558,12 @@ object JChatGPT : KotlinPlugin( * @param record 消息记录 * @param event 消息事件 */ - fun appendMessageRecord( + private fun appendMessageRecord( historyText: StringBuilder, record: MessageRecord, event: MessageEvent, replyIndex: ReplyIndex, + imageIndex: ImageIndex, showSender: Boolean, showTime: Boolean, ) { @@ -573,24 +590,23 @@ object JChatGPT : KotlinPlugin( } recordMessage[QuoteReply.Key]?.let { - appendQuoteMarker(historyText, it, event.subject, replyIndex) + appendQuoteMarker(historyText, it, event.subject, replyIndex, imageIndex) } - historyText.appendLine(formatRecordContent(recordMessage, event.subject)) + historyText.appendLine(formatRecordContent(recordMessage, event.subject, imageIndex)) } - private fun singleMessageToText(it: SingleMessage): String { + private fun singleMessageToText(it: SingleMessage, imageIndex: ImageIndex): String { return when (it) { // 完整展开合并转发内容，便于 LLM 阅读分析转发的对话（依赖大上下文+缓存，不做截断） - is ForwardMessage -> formatForward(it, 1) + is ForwardMessage -> formatForward(it, 1, imageIndex) // 图片格式化 is Image -> { try { - val imageUrl = runBlocking { - it.queryUrl() - } - "![${if (it.isEmoji) "表情包" else "图片"}]($imageUrl)" + val imageUrl = runBlocking { it.queryUrl() } + val index = imageIndex.add(it.imageId, imageUrl) + "[${if (it.isEmoji) "表情包" else "图片"}$index]" } catch (e: Throwable) { logger.warning("图片地址获取失败", e) it.content @@ -605,7 +621,7 @@ object JChatGPT : KotlinPlugin( * 递归展开合并转发消息，用 Markdown 引用块表示：每加深一层嵌套多一个 `>`（>、>>、>>>…）。 * @param depth 当前嵌套层级，从 1 开始 */ - private fun formatForward(forward: ForwardMessage, depth: Int): String = buildString { + private fun formatForward(forward: ForwardMessage, depth: Int, imageIndex: ImageIndex): String = buildString { val quote = ">".repeat(depth) + " " append("[转发消息·").append(forward.nodeList.size).append("条") if (forward.title.isNotEmpty()) append(':').append(forward.title) @@ -618,10 +634,10 @@ object JChatGPT : KotlinPlugin( node.messageChain.forEach { sub -> if (sub is ForwardMessage) { // 嵌套转发：层级加深，自带更深的 `>` 前缀，无需再次缩进 - append(formatForward(sub, depth + 1)) + append(formatForward(sub, depth + 1, imageIndex)) } else { // 其它内容：多行正文对齐到当前引用层级 - append(singleMessageToText(sub).replace("\n", "\n$quote")) + append(singleMessageToText(sub, imageIndex).replace("\n", "\n$quote")) } } } @@ -658,7 +674,9 @@ object JChatGPT : KotlinPlugin( // 回复索引与对话上下文同寿命：复用缓存时沿用旧索引，保证 LLM 看到的 [n] 编号连续不串号； // 否则新建（供 sendSingleMessage 的 replyTo 按编号引用历史消息） val replyIndex = if (reuseCache) cache!!.replyIndex else ReplyIndex() + val imageIndex = if (reuseCache) cache!!.imageIndex else ImageIndex() replyIndexMap[subjectId] = replyIndex + imageIndexMap[subjectId] = imageIndex val history = if (reuseCache) { // 缓存有效，复用历史 logger.info("使用缓存的对话上下文，包含 ${cache!!.history.size} 条互动消息") @@ -868,7 +886,8 @@ object JChatGPT : KotlinPlugin( contextCache[subjectId] = ConversationCache( history = history, lastActivityAt = startedAt, - replyIndex = replyIndex + replyIndex = replyIndex, + imageIndex = imageIndex, ) logger.debug("已保存对话上下文到缓存") } @@ -901,6 +920,7 @@ object JChatGPT : KotlinPlugin( } finally { // 清理本轮回复索引 replyIndexMap.remove(event.subject.id) + imageIndexMap.remove(event.subject.id) // 一段时间后才允许再次提问，防止高频对话 launch { delay(500.milliseconds) diff --git a/src/main/kotlin/tools/ImageAgent.kt b/src/main/kotlin/tools/ImageAgent.kt index d43b59e..33bacd0 100644 --- a/src/main/kotlin/tools/ImageAgent.kt +++ b/src/main/kotlin/tools/ImageAgent.kt @@ -13,31 +13,34 @@ import kotlinx.serialization.json.JsonObject import kotlinx.serialization.json.add import kotlinx.serialization.json.addJsonObject import kotlinx.serialization.json.buildJsonObject +import kotlinx.serialization.json.int import kotlinx.serialization.json.jsonArray import kotlinx.serialization.json.jsonObject import kotlinx.serialization.json.jsonPrimitive import kotlinx.serialization.json.put import kotlinx.serialization.json.putJsonArray import kotlinx.serialization.json.putJsonObject +import net.mamoe.mirai.event.events.MessageEvent import top.jie65535.mirai.JChatGPT import top.jie65535.mirai.PluginConfig class ImageAgent : BaseAgent( tool = Tool.function( name = "imageAgent", - description = "调用千问图像模型生成或编辑图片。不传 image_urls 即纯文生图；" + + description = "调用千问图像模型生成或编辑图片。不传 image_indices 即纯文生图；" + "传 1~3 张图片可进行编辑、修改或多图融合。" + "备注：该方法成本较高，非必要尽量不要调用。" + "编辑图片前无需识别图片内容，模型自己会理解图片内容。", parameters = Parameters.buildJsonObject { put("type", "object") putJsonObject("properties") { - putJsonObject("image_urls") { + putJsonObject("image_indices") { put("type", "array") putJsonObject("items") { - put("type", "string") + put("type", "integer") + put("minimum", 1) } - put("description", "参考图片地址列表，可传 0~3 张。" + + put("description", "用户消息中[图片n]或[表情包n]标记的参考图片编号，可传 0~3 张。" + "不传或为空即纯文生图；传 1 张为编辑；多张为融合，输出比例与最后一张对齐。") } putJsonObject("prompt") { @@ -61,12 +64,17 @@ class ImageAgent : BaseAgent( override val loadingMessage: String get() = "作图中..." - override suspend fun execute(args: JsonObject?): String { + override suspend fun execute(args: JsonObject?, event: MessageEvent): String { requireNotNull(args) val prompt = args.getValue("prompt").jsonPrimitive.content - val imageUrls = args["image_urls"]?.jsonArray - ?.map { it.jsonPrimitive.content } + val imageIndices = args["image_indices"]?.jsonArray + ?.map { it.jsonPrimitive.int } ?: emptyList() + require(imageIndices.size <= 3) { "参考图片最多只能传3张" } + val imageUrls = imageIndices.map { imageIndex -> + JChatGPT.lookupImageUrl(event.subject.id, imageIndex) + ?: throw IllegalArgumentException("图片编号[$imageIndex]不存在或已失效") + } val response = httpClient.post(API_URL) { contentType(ContentType("application", "json")) diff --git a/src/main/kotlin/tools/SearchChatHistory.kt b/src/main/kotlin/tools/SearchChatHistory.kt index dd34243..009f2fe 100644 --- a/src/main/kotlin/tools/SearchChatHistory.kt +++ b/src/main/kotlin/tools/SearchChatHistory.kt @@ -172,19 +172,21 @@ class SearchChatHistory : BaseAgent( .append("：") } for (msg in record.toMessageChain()) { - sb.append(singleMessageToText(msg)) + sb.append(singleMessageToText(msg, event.subject.id)) } sb.appendLine() lastFromId = record.fromId } } - private suspend fun singleMessageToText(msg: SingleMessage): String { + private suspend fun singleMessageToText(msg: SingleMessage, subjectId: Long): String { return when (msg) { is Image -> { try { - val url = msg.queryUrl() - "![${if (msg.isEmoji) "表情包" else "图片"}]($url)" + val imageUrl = msg.queryUrl() + val index = JChatGPT.registerImage(subjectId, msg.imageId, imageUrl) + ?: return msg.content + "[${if (msg.isEmoji) "表情包" else "图片"}$index]" } catch (_: Throwable) { msg.content } diff --git a/src/main/kotlin/tools/VisualAgent.kt b/src/main/kotlin/tools/VisualAgent.kt index 1db29ab..43fa23b 100644 --- a/src/main/kotlin/tools/VisualAgent.kt +++ b/src/main/kotlin/tools/VisualAgent.kt @@ -11,6 +11,7 @@ import com.aallam.openai.api.model.ModelId import io.ktor.client.plugins.ClientRequestException import kotlinx.serialization.json.JsonObject import kotlinx.serialization.json.add +import kotlinx.serialization.json.int import kotlinx.serialization.json.jsonArray import kotlinx.serialization.json.jsonPrimitive import kotlinx.serialization.json.put @@ -20,6 +21,7 @@ import kotlinx.coroutines.CancellationException import kotlinx.coroutines.delay import kotlinx.coroutines.sync.Semaphore import kotlinx.coroutines.sync.withPermit +import net.mamoe.mirai.event.events.MessageEvent import top.jie65535.mirai.JChatGPT import top.jie65535.mirai.LargeLanguageModels import top.jie65535.mirai.PluginConfig @@ -32,13 +34,14 @@ class VisualAgent : BaseAgent( parameters = Parameters.buildJsonObject { put("type", "object") putJsonObject("properties") { - putJsonObject("image_urls") { + putJsonObject("image_indices") { put("type", "array") - put("description", "图片地址数组，按用户消息中的出现顺序传入") + put("description", "用户消息中[图片n]或[表情包n]标记的图片编号数组，按需要理解的顺序传入") put("minItems", 1) put("maxItems", MAX_SOURCE_IMAGES) putJsonObject("items") { - put("type", "string") + put("type", "integer") + put("minimum", 1) } } putJsonObject("prompt") { @@ -47,7 +50,7 @@ class VisualAgent : BaseAgent( } } putJsonArray("required") { - add("image_urls") + add("image_indices") add("prompt") } } @@ -62,25 +65,35 @@ class VisualAgent : BaseAgent( override val isEnabled: Boolean get() = LargeLanguageModels.visual != null - override suspend fun execute(args: JsonObject?): String { + override suspend fun execute(args: JsonObject?, event: MessageEvent): String { requireNotNull(args) val llm = LargeLanguageModels.visual ?: return "未配置llm，无法进行识别。" - val imageUrls = args["image_urls"]?.jsonArray - ?.map { it.jsonPrimitive.content } - ?.filter { it.isNotBlank() } + val imageIndices = args["image_indices"]?.jsonArray + ?.map { it.jsonPrimitive.int } ?.ifEmpty { null } ?: throw IllegalArgumentException("至少需要提供一张图片") - require(imageUrls.size <= MAX_SOURCE_IMAGES) { "单次最多处理 $MAX_SOURCE_IMAGES 张用户图片" } + require(imageIndices.size <= MAX_SOURCE_IMAGES) { "单次最多处理 $MAX_SOURCE_IMAGES 张用户图片" } + val imageUrls = imageIndices.map { imageIndex -> + JChatGPT.lookupImageUrl(event.subject.id, imageIndex) + ?: throw IllegalArgumentException("图片编号[$imageIndex]不存在或已失效") + } val prompt = args.getValue("prompt").jsonPrimitive.content return concurrencyLimiter.withPermit { val imageGroups = imageUrls.mapIndexed { index, imageUrl -> if (PluginConfig.visualImageBase64Enabled) { - val resolved = imageResolver.resolve(imageUrl) val host = runCatching { URI(imageUrl).host }.getOrNull() ?: "unknown" + val resolved = try { + imageResolver.resolve(imageUrl) + } catch (e: Throwable) { + JChatGPT.logger.error( + "视觉图片下载失败: image=${imageIndices[index]}, url=$imageUrl" + ) + throw e + } val mimeTypes = resolved.images.map { it.mimeType }.distinct().joinToString() JChatGPT.logger.info( - "视觉图片已本地化: source=${index + 1}/${imageUrls.size}, host=$host, " + + "视觉图片已本地化: image=${imageIndices[index]}, source=${index + 1}/${imageUrls.size}, host=$host, " + "parts=${resolved.images.size}, mime=$mimeTypes, " + "sourceBytes=${resolved.sourceSize}, payloadChars=${resolved.payloadSize}, " + "transcoded=${resolved.transcoded}" diff --git a/src/main/kotlin/tools/VisualImageResolver.kt b/src/main/kotlin/tools/VisualImageResolver.kt index f051f90..b9e02fa 100644 --- a/src/main/kotlin/tools/VisualImageResolver.kt +++ b/src/main/kotlin/tools/VisualImageResolver.kt @@ -108,8 +108,15 @@ internal class VisualImageResolver { } if (!response.status.isSuccess()) { - response.bodyAsChannel().cancel() - throw IllegalArgumentException("图片下载失败：HTTP ${response.status.value}") + val errorBody = readErrorBody(response.bodyAsChannel()) + val errorNumber = response.headers["X-ErrNo"] + throw IllegalArgumentException( + buildString { + append("图片下载失败：HTTP ").append(response.status.value) + if (!errorNumber.isNullOrBlank()) append("，X-ErrNo=").append(errorNumber) + if (errorBody.isNotBlank()) append("，响应=").append(errorBody) + } + ) } val declaredLength = response.headers[HttpHeaders.ContentLength]?.toLongOrNull() @@ -190,6 +197,31 @@ internal class VisualImageResolver { } } + private suspend fun readErrorBody(channel: io.ktor.utils.io.ByteReadChannel): String { + val output = ByteArrayOutputStream() + val buffer = ByteArray(DOWNLOAD_BUFFER_SIZE) + var total = 0 + try { + while (total < MAX_ERROR_RESPONSE_BYTES) { + val count = channel.readAvailable( + buffer, + 0, + min(buffer.size, MAX_ERROR_RESPONSE_BYTES - total) + ) + if (count < 0) break + if (count == 0) continue + output.write(buffer, 0, count) + total += count + } + } finally { + channel.cancel() + } + return output.toByteArray() + .toString(Charsets.UTF_8) + .replace(Regex("[\\r\\n]+"), " ") + .trim() + } + private fun buildPayload(bytes: ByteArray, mimeType: String): ImagePayload { val encoded = Base64.getEncoder().encodeToString(bytes) val dataUrl = "data:$mimeType;base64,$encoded" @@ -612,6 +644,7 @@ internal class VisualImageResolver { private const val LONG_IMAGE_MAX_OVERLAP = 256 private const val MAX_LONG_IMAGE_PARTS = 16 private const val MAX_COMPRESSION_ROUNDS = 6 + private const val MAX_ERROR_RESPONSE_BYTES = 4096 private const val DOWNSCALE_FACTOR = 0.82 private const val USER_AGENT = "JChatGPT/1.13 image-fetcher" private val JPEG_QUALITIES = floatArrayOf(0.90f, 0.82f, 0.74f, 0.66f) diff --git a/src/test/kotlin/ImageIndexTest.kt b/src/test/kotlin/ImageIndexTest.kt new file mode 100644 index 0000000..abe4bdb --- /dev/null +++ b/src/test/kotlin/ImageIndexTest.kt @@ -0,0 +1,32 @@ +package top.jie65535.mirai + +import kotlin.test.Test +import kotlin.test.assertEquals +import kotlin.test.assertNull + +class ImageIndexTest { + @Test + fun `assigns short sequential indices`() { + val index = ImageIndex() + + assertEquals(1, index.add("image-a", "https://example.com/a")) + assertEquals(2, index.add("image-b", "https://example.com/b")) + assertEquals("https://example.com/a", index.getUrl(1)) + assertEquals("https://example.com/b", index.getUrl(2)) + } + + @Test + fun `reuses index for repeated image id`() { + val index = ImageIndex() + + assertEquals(1, index.add("image-a", "https://example.com/a-old")) + assertEquals(1, index.add("image-a", "https://example.com/a-new")) + assertEquals(2, index.add("image-b", "https://example.com/b")) + assertEquals("https://example.com/a-new", index.getUrl(1)) + } + + @Test + fun `returns null for unknown index`() { + assertNull(ImageIndex().getUrl(1)) + } +}