diff --git a/packages/onebot/src/event-converter/element-codecs.ts b/packages/onebot/src/event-converter/element-codecs.ts
new file mode 100644
index 00000000..2ed88ee1
--- /dev/null
+++ b/packages/onebot/src/event-converter/element-codecs.ts
@@ -0,0 +1,409 @@
+import { createLogger } from '@snowluma/common/logger';
+import type { MessageElement } from '@snowluma/protocol/events';
+import type { JsonObject } from '../types';
+import type { ParseMessageOptions } from '../message-parser';
+import type {
+  ImageUrlResolver,
+  MediaUrlResolver,
+  MessageIdResolver,
+  MediaSegmentSink,
+} from './index';
+import { resolveReplyId } from './utils';
+
+// ─────────────────────────────────────────────────────────────────────────
+// 消息元素 codec 表（onebot 侧）—— 把「同一种元素」的两个 onebot 方向并到一处：
+//   S 收·转  toSegment    MessageElement → OneBot 段
+//   P 发·解  fromSegment  OneBot 段 → MessageElement
+// 历史上这两向分散在 to-segment.ts 与 message-parser.ts、各写各的，容易一起漂。
+// 现在每种元素类型一条 { toSegment?, fromSegment? } 条目，谁少写一向一眼可见，
+// 并由 element-manifest 对账测试（onebot 侧）拿本表的键去核对清单。
+//
+// 第 1 步（收·解，proto 字段分派、异构）与第 4 步（发·打包，protocol 包）不在本表，
+// 见 element-manifest.ts 的说明。纯 OneBot 输入糖（骰子/分享/…）也不进表，留在
+// message-parser 当前置 normalize。
+//
+// 行为对 to-segment / message-parser 的原实现 byte 级不变——仅把分支体平移到此。
+// ─────────────────────────────────────────────────────────────────────────
+
+const log = createLogger('MsgParser');
+
+/** toSegment（S 收·转）所需的上下文：会话信息 + 各类 URL/媒体解析器。 */
+export interface ToSegmentContext {
+  isGroup: boolean;
+  sessionId: number;
+  imageUrlResolver?: ImageUrlResolver | null;
+  mediaUrlResolver?: MediaUrlResolver | null;
+  messageIdResolver?: MessageIdResolver | null;
+  mediaSegmentSink?: MediaSegmentSink | null;
+}
+
+export interface ElementCodec {
+  /** S 收·转：MessageElement → OneBot 段。 */
+  toSegment?: (element: MessageElement, ctx: ToSegmentContext) => Promise<JsonObject>;
+  /** P 发·解：OneBot 段 data → MessageElement（null = 丢弃该段）。 */
+  fromSegment?: (data: Record<string, unknown>, options?: ParseMessageOptions) => Promise<MessageElement | null>;
+}
+
+// ── 共享低层工具（原在 message-parser，移来供本表与 message-parser 的输入糖共用）──
+
+export function intOr(value: unknown, fallback = 0): number {
+  if (value === undefined || value === null) return fallback;
+  if (typeof value === 'number') return Number.isFinite(value) ? Math.trunc(value) : fallback;
+  const n = parseInt(String(value), 10);
+  return Number.isFinite(n) ? n : fallback;
+}
+
+/** Build a market-face (`mface`) element from an OneBot segment's data.
+ *  Shared by the dedicated `mface` segment and the `image`-with-`emoji_id`
+ *  round-trip path. `emojiId` is the hex GUID the wire builder converts back
+ *  to `MarketFace.faceId`. */
+export function marketFaceElement(emojiId: string, data: Record<string, unknown>): MessageElement {
+  return {
+    type: 'mface',
+    text: String(data.summary ?? data.name ?? ''),
+    emojiId,
+    emojiPackageId: intOr(data.emoji_package_id ?? data.tab_id, 0),
+    emojiKey: String(data.key ?? ''),
+  };
+}
+
+/**
+ * Pick the best loadable source from a media segment's `file` / `url` / `path`
+ * / `media` fields.
+ *
+ * `file` is normally the canonical OneBot field and wins, but it can also be a
+ * QQ-internal media id (e.g. `<md5>.png`) that this process cannot resolve to a
+ * local path. When a bot framework echoes a received image back (Yunzai et al.
+ * resend the original `file=<md5>.ext` together with the download `url`), using
+ * `file` makes the send path `statSync` the id as a bogus local path and throw
+ * `ENOENT`. So: keep `file` when it is a directly loadable source (inline
+ * bytes, a remote url, or a filesystem path with a separator); otherwise, if a
+ * real http(s) `url` accompanies it, prefer that. (issue #155)
+ */
+export function pickMediaSource(data: Record<string, unknown>): string {
+  const file = String(data.file ?? '').trim();
+  const url = String(data.url ?? '').trim();
+  const fallback = file || url || String(data.path ?? '').trim() || String(data.media ?? '').trim();
+  if (!file) return fallback;
+  // `file` is itself loadable: inline bytes, a remote url, or a path (anything
+  // carrying a `/` or `\` separator, incl. file:// and absolute/relative paths).
+  if (/^(base64:\/\/|data:|https?:\/\/|file:\/\/)/i.test(file) || /[\\/]/.test(file)) return file;
+  // `file` is a bare token (QQ-internal id) — fall back to a real url if present.
+  if (/^https?:\/\//i.test(url)) return url;
+  return fallback;
+}
+
+// ── codec 表：一种元素类型一条，键即 element.type（收·转）/ 段 type（发·解，二者同名）──
+
+export const ELEMENT_CODECS: Record<string, ElementCodec> = {
+  text: {
+    async toSegment(element) {
+      return { type: 'text', data: { text: element.text ?? '' } };
+    },
+    async fromSegment(data) {
+      const text = String(data.text ?? '');
+      return text ? { type: 'text', text } : null;
+    },
+  },
+
+  face: {
+    async toSegment(element) {
+      return { type: 'face', data: { id: String(element.faceId ?? 0) } };
+    },
+    async fromSegment(data) {
+      const id = intOr(data.id, -1);
+      if (id < 0) return null;
+      return { type: 'face', faceId: id };
+    },
+  },
+
+  at: {
+    async toSegment(element) {
+      const qq = (element.uid === 'all' || element.targetUin === 0)
+        ? 'all'
+        : String(element.targetUin ?? 0);
+      return { type: 'at', data: { qq } };
+    },
+    async fromSegment(data, options) {
+      const qq = String(data.qq ?? '').trim();
+      if (qq === 'all') {
+        return { type: 'at', targetUin: 0, uid: 'all', text: '@全体成员 ' };
+      }
+      const uin = intOr(qq, 0);
+      if (uin <= 0) return null;
+
+      const name = String(data.name ?? data.nickname ?? data.card ?? '').trim();
+      let uid = String(data.uid ?? '').trim();
+      if (!uid && options?.resolveMentionUid) {
+        uid = (await options.resolveMentionUid(uin))?.trim() ?? '';
+      }
+      const element: MessageElement = { type: 'at', targetUin: uin };
+      if (uid) element.uid = uid;
+      if (name) element.text = `@${name} `;
+      return element;
+    },
+  },
+
+  reply: {
+    async toSegment(element, ctx) {
+      const id = resolveReplyId(ctx.isGroup, ctx.sessionId, element.replySeq ?? 0, ctx.messageIdResolver);
+      return { type: 'reply', data: { id: String(id) } };
+    },
+    async fromSegment(data, options) {
+      const id = intOr(data.id, 0);
+      if (id === 0) return null;
+
+      if (options?.resolveReplySequence) {
+        const resolved = options.resolveReplySequence(id);
+        if (typeof resolved === 'number' && resolved > 0) {
+          const element: MessageElement = {
+            type: 'reply',
+            replySeq: resolved,
+            replyMessageId: id  // Keep the original messageId for logging
+          };
+
+          // Try to get additional meta info for better reply display
+          if (options?.resolveReplyMeta) {
+            const meta = options.resolveReplyMeta(id);
+            if (meta) {
+              element.replySenderUin = meta.senderUin;
+              element.replyTime = meta.time;
+              element.replyRandom = meta.random;
+            }
+          }
+
+          return element;
+        }
+      }
+
+      // Backward-compatible path: allow direct seq reply IDs.
+      return id > 0 ? { type: 'reply', replySeq: id } : null;
+    },
+  },
+
+  image: {
+    async toSegment(element, ctx) {
+      const url = ctx.imageUrlResolver ? await ctx.imageUrlResolver(element, ctx.isGroup) : (element.imageUrl ?? '');
+      const data: JsonObject = {
+        url,
+        file: element.fileId ?? '',
+        sub_type: element.subType ?? 0,
+        summary: element.summary ?? '',
+      };
+      if (ctx.mediaSegmentSink) ctx.mediaSegmentSink('image', element, data, ctx.isGroup, ctx.sessionId);
+      return { type: 'image', data };
+    },
+    async fromSegment(data) {
+      // A market face that was surfaced as an `image` (see toSegment) can be
+      // echoed straight back: when `emoji_id` is present we rebuild the market
+      // face instead of re-uploading the gif as a plain picture.
+      const imgEmojiId = String(data.emoji_id ?? '').trim();
+      if (imgEmojiId) return marketFaceElement(imgEmojiId, data);
+      return {
+        type: 'image',
+        url: pickMediaSource(data),
+        flash: data.type === 'flash',
+        subType: intOr(data.subType, 0),
+        summary: data.summary ? String(data.summary) : undefined,
+      };
+    },
+  },
+
+  record: {
+    async toSegment(element, ctx) {
+      const url = ctx.mediaUrlResolver ? await ctx.mediaUrlResolver(element, ctx.isGroup, ctx.sessionId) : (element.url ?? '');
+      const data: JsonObject = {
+        file: element.fileName ?? element.fileId ?? '',
+        url,
+      };
+      if (ctx.mediaSegmentSink) ctx.mediaSegmentSink('record', element, data, ctx.isGroup, ctx.sessionId);
+      return { type: 'record', data };
+    },
+    async fromSegment(data) {
+      const source = pickMediaSource(data);
+      if (!source) return null;
+      return {
+        type: 'record',
+        url: source,
+      };
+    },
+  },
+
+  video: {
+    async toSegment(element, ctx) {
+      const url = ctx.mediaUrlResolver ? await ctx.mediaUrlResolver(element, ctx.isGroup, ctx.sessionId) : (element.url ?? '');
+      const data: JsonObject = {
+        file: element.fileName ?? element.fileId ?? '',
+        url,
+      };
+      if (ctx.mediaSegmentSink) ctx.mediaSegmentSink('video', element, data, ctx.isGroup, ctx.sessionId);
+      return { type: 'video', data };
+    },
+    async fromSegment(data) {
+      const source = pickMediaSource(data);
+      if (!source) return null;
+      return {
+        type: 'video',
+        url: source,
+        thumbUrl: data.thumb ? String(data.thumb) : undefined,
+      };
+    },
+  },
+
+  json: {
+    async toSegment(element) {
+      return { type: 'json', data: { data: element.text ?? '' } };
+    },
+    async fromSegment(data) {
+      return {
+        type: 'json',
+        text: String(data.data ?? ''),
+      };
+    },
+  },
+
+  xml: {
+    async toSegment(element) {
+      return {
+        type: 'xml',
+        data: {
+          data: element.text ?? '',
+          resid: element.subType ?? 35,
+        },
+      };
+    },
+    async fromSegment(data) {
+      return {
+        type: 'xml',
+        text: String(data.data ?? ''),
+        subType: intOr(data.id, 0),
+      };
+    },
+  },
+
+  file: {
+    async toSegment(element, ctx) {
+      const url = ctx.mediaUrlResolver ? await ctx.mediaUrlResolver(element, ctx.isGroup, ctx.sessionId) : (element.url ?? '');
+      const fileName = element.fileName ?? '';
+      const fileSize = element.fileSize ?? 0;
+      const fileId = element.fileId ?? '';
+      return {
+        type: 'file',
+        data: {
+          // NapCat/LLOneBot-style canonical fields — most downstream
+          // OneBot adapters read these (`file`/`file_id`/`file_size`).
+          file: fileName,
+          file_id: fileId,
+          file_size: fileSize,
+          // Legacy SnowLuma field names, kept for backward compat with
+          // any consumer that already reads name/size/id.
+          name: fileName,
+          size: fileSize,
+          id: fileId,
+          url,
+          file_hash: element.fileHash ?? '',
+        },
+      };
+    },
+    async fromSegment(data) {
+      const fileId = String(data.file_id ?? data.fileId ?? '').trim();
+      const source = String(data.file ?? data.url ?? data.path ?? '').trim();
+      if (!fileId && !source) {
+        log.warn('[MsgParser] file segment without file_id or file/url is unsupported');
+        return null;
+      }
+      const fileName = String(data.name ?? data.filename ?? data.fileName ?? '').trim();
+      const fileSize = intOr(data.size ?? data.fileSize, 0);
+      const md5Hex = String(data.md5 ?? data.md5Hex ?? '').trim();
+      const sha1Hex = String(data.sha1 ?? data.sha1Hex ?? '').trim();
+      const fileHash = String(data.file_hash ?? data.fileHash ?? '').trim();
+      const elem: MessageElement = fileId ? { type: 'file', fileId } : { type: 'file', url: source };
+      if (fileName) elem.fileName = fileName;
+      if (fileSize > 0) elem.fileSize = fileSize;
+      if (md5Hex) elem.md5Hex = md5Hex;
+      if (sha1Hex) elem.sha1Hex = sha1Hex;
+      if (fileHash) elem.fileHash = fileHash;
+      return elem;
+    },
+  },
+
+  mface: {
+    async toSegment(element) {
+      // Unify market faces (商城表情) to an `image` segment so OneBot clients
+      // that don't special-case `mface` still render the sticker, while the
+      // `emoji_id`/`emoji_package_id`/`key` markers let aware clients (and our
+      // own send path) reproduce it as a real market face. Mirrors NapCat's
+      // marketFaceElement → image conversion. The gxh URL is a self-contained
+      // external link (no rkey), so we set it directly and skip mediaSegmentSink.
+      const emojiId = element.emojiId ?? '';
+      const dir = emojiId.slice(0, 2);
+      const url = emojiId
+        ? `https://gxh.vip.qq.com/club/item/parcel/item/${dir}/${emojiId}/raw300.gif`
+        : '';
+      return {
+        type: 'image',
+        data: {
+          file: emojiId ? `${dir}-${emojiId}.gif` : '',
+          url,
+          summary: element.text ?? '',
+          sub_type: 0,
+          emoji_id: emojiId,
+          emoji_package_id: element.emojiPackageId ?? 0,
+          key: element.emojiKey ?? '',
+        },
+      };
+    },
+    async fromSegment(data) {
+      // Market face (商城表情). emoji_id is the hex GUID; without it we can't
+      // construct the wire element, so drop the segment.
+      const emojiId = String(data.emoji_id ?? '').trim();
+      if (!emojiId) {
+        log.warn('[MsgParser] mface segment without emoji_id is unsupported');
+        return null;
+      }
+      return marketFaceElement(emojiId, data);
+    },
+  },
+
+  poke: {
+    async toSegment(element) {
+      return {
+        type: 'poke',
+        data: {
+          type: element.subType ?? 0,
+        },
+      };
+    },
+    async fromSegment(data) {
+      return {
+        type: 'poke',
+        faceId: intOr(data.type ?? data.id, 0),
+      };
+    },
+  },
+
+  forward: {
+    async toSegment(element) {
+      return {
+        type: 'forward',
+        data: { id: element.resId ?? '' },
+      };
+    },
+    async fromSegment(data) {
+      return {
+        type: 'forward',
+        resId: String(data.id ?? ''),
+      };
+    },
+  },
+
+  markdown: {
+    // 收侧（S）无对应，仅发·解存在。
+    async fromSegment(data) {
+      return {
+        type: 'markdown',
+        text: String(data.content ?? ''),
+      };
+    },
+  },
+};
diff --git a/packages/onebot/src/event-converter/to-segment.ts b/packages/onebot/src/event-converter/to-segment.ts
index db5bc33d..80199630 100644
--- a/packages/onebot/src/event-converter/to-segment.ts
+++ b/packages/onebot/src/event-converter/to-segment.ts
@@ -6,7 +6,7 @@ import type {
   MediaUrlResolver,
   MessageIdResolver,
 } from './index';
-import { resolveReplyId } from './utils';
+import { ELEMENT_CODECS } from './element-codecs';
 import { createLogger } from '@snowluma/common/logger';
 
 const log = createLogger('OneBot');
@@ -46,136 +46,17 @@ async function elementToSegment(
   messageIdResolver?: MessageIdResolver | null,
   mediaSegmentSink?: MediaSegmentSink | null,
 ): Promise<JsonObject> {
-  if (element.type === 'text') {
-    return { type: 'text', data: { text: element.text ?? '' } };
-  }
-
-  if (element.type === 'face') {
-    return { type: 'face', data: { id: String(element.faceId ?? 0) } };
-  }
-
-  if (element.type === 'image') {
-    const url = imageUrlResolver ? await imageUrlResolver(element, isGroup) : (element.imageUrl ?? '');
-    const data: JsonObject = {
-      url,
-      file: element.fileId ?? '',
-      sub_type: element.subType ?? 0,
-      summary: element.summary ?? '',
-    };
-    if (mediaSegmentSink) mediaSegmentSink('image', element, data, isGroup, sessionId);
-    return { type: 'image', data };
-  }
-
-  if (element.type === 'at') {
-    const qq = (element.uid === 'all' || element.targetUin === 0)
-      ? 'all'
-      : String(element.targetUin ?? 0);
-    return { type: 'at', data: { qq } };
-  }
-
-  if (element.type === 'reply') {
-    const id = resolveReplyId(isGroup, sessionId, element.replySeq ?? 0, messageIdResolver);
-    return { type: 'reply', data: { id: String(id) } };
-  }
-
-  if (element.type === 'record') {
-    const url = mediaUrlResolver ? await mediaUrlResolver(element, isGroup, sessionId) : (element.url ?? '');
-    const data: JsonObject = {
-      file: element.fileName ?? element.fileId ?? '',
-      url,
-    };
-    if (mediaSegmentSink) mediaSegmentSink('record', element, data, isGroup, sessionId);
-    return { type: 'record', data };
-  }
-
-  if (element.type === 'video') {
-    const url = mediaUrlResolver ? await mediaUrlResolver(element, isGroup, sessionId) : (element.url ?? '');
-    const data: JsonObject = {
-      file: element.fileName ?? element.fileId ?? '',
-      url,
-    };
-    if (mediaSegmentSink) mediaSegmentSink('video', element, data, isGroup, sessionId);
-    return { type: 'video', data };
-  }
-
-  if (element.type === 'json') {
-    return { type: 'json', data: { data: element.text ?? '' } };
-  }
-
-  if (element.type === 'xml') {
-    return {
-      type: 'xml',
-      data: {
-        data: element.text ?? '',
-        resid: element.subType ?? 35,
-      },
-    };
-  }
-
-  if (element.type === 'file') {
-    const url = mediaUrlResolver ? await mediaUrlResolver(element, isGroup, sessionId) : (element.url ?? '');
-    const fileName = element.fileName ?? '';
-    const fileSize = element.fileSize ?? 0;
-    const fileId = element.fileId ?? '';
-    return {
-      type: 'file',
-      data: {
-        // NapCat/LLOneBot-style canonical fields — most downstream
-        // OneBot adapters read these (`file`/`file_id`/`file_size`).
-        file: fileName,
-        file_id: fileId,
-        file_size: fileSize,
-        // Legacy SnowLuma field names, kept for backward compat with
-        // any consumer that already reads name/size/id.
-        name: fileName,
-        size: fileSize,
-        id: fileId,
-        url,
-        file_hash: element.fileHash ?? '',
-      },
-    };
-  }
-
-  if (element.type === 'mface') {
-    // Unify market faces (商城表情) to an `image` segment so OneBot clients
-    // that don't special-case `mface` still render the sticker, while the
-    // `emoji_id`/`emoji_package_id`/`key` markers let aware clients (and our
-    // own send path) reproduce it as a real market face. Mirrors NapCat's
-    // marketFaceElement → image conversion. The gxh URL is a self-contained
-    // external link (no rkey), so we set it directly and skip mediaSegmentSink.
-    const emojiId = element.emojiId ?? '';
-    const dir = emojiId.slice(0, 2);
-    const url = emojiId
-      ? `https://gxh.vip.qq.com/club/item/parcel/item/${dir}/${emojiId}/raw300.gif`
-      : '';
-    return {
-      type: 'image',
-      data: {
-        file: emojiId ? `${dir}-${emojiId}.gif` : '',
-        url,
-        summary: element.text ?? '',
-        sub_type: 0,
-        emoji_id: emojiId,
-        emoji_package_id: element.emojiPackageId ?? 0,
-        key: element.emojiKey ?? '',
-      },
-    };
-  }
-
-  if (element.type === 'poke') {
-    return {
-      type: 'poke',
-      data: {
-        type: element.subType ?? 0,
-      },
-    };
-  }
-
-  if (element.type === 'forward') {
-    return {
-      type: 'forward',
-      data: { id: element.resId ?? '' },
-    };
+  // S 收·转：按 element.type 查 codec 表；缺条目则走 default 透传（保持原兜底）。
+  const codec = ELEMENT_CODECS[element.type];
+  if (codec?.toSegment) {
+    return codec.toSegment(element, {
+      isGroup,
+      sessionId,
+      imageUrlResolver,
+      mediaUrlResolver,
+      messageIdResolver,
+      mediaSegmentSink,
+    });
   }
   return { type: element.type, data: {} };
 }
diff --git a/packages/onebot/src/message-parser.ts b/packages/onebot/src/message-parser.ts
index 5dd7ae32..0932fcee 100644
--- a/packages/onebot/src/message-parser.ts
+++ b/packages/onebot/src/message-parser.ts
@@ -1,6 +1,7 @@
 import { createLogger } from '@snowluma/common/logger';
 import type { MessageElement } from '@snowluma/protocol/events';
 import { parseFromCQString } from './helper/cq';
+import { ELEMENT_CODECS, intOr } from './event-converter/element-codecs';
 import type { JsonValue } from './types';
 
 const log = createLogger('MsgParser');
@@ -17,27 +18,6 @@ export interface ParseMessageOptions {
 
 export const CQ_REGEX = /\[CQ:([A-Za-z]+)(?:,([^\]]*))?\]/g;
 
-function intOr(value: unknown, fallback = 0): number {
-  if (value === undefined || value === null) return fallback;
-  if (typeof value === 'number') return Number.isFinite(value) ? Math.trunc(value) : fallback;
-  const n = parseInt(String(value), 10);
-  return Number.isFinite(n) ? n : fallback;
-}
-
-/** Build a market-face (`mface`) element from an OneBot segment's data.
- *  Shared by the dedicated `mface` segment and the `image`-with-`emoji_id`
- *  round-trip path. `emojiId` is the hex GUID the wire builder converts back
- *  to `MarketFace.faceId`. */
-function marketFaceElement(emojiId: string, data: Record<string, unknown>): MessageElement {
-  return {
-    type: 'mface',
-    text: String(data.summary ?? data.name ?? ''),
-    emojiId,
-    emojiPackageId: intOr(data.emoji_package_id ?? data.tab_id, 0),
-    emojiKey: String(data.key ?? ''),
-  };
-}
-
 export function parseCQParams(raw: string): Record<string, string> {
   const params: Record<string, string> = {};
   if (!raw) return params;
@@ -54,32 +34,6 @@ export function parseCQParams(raw: string): Record<string, string> {
   return params;
 }
 
-/**
- * Pick the best loadable source from a media segment's `file` / `url` / `path`
- * / `media` fields.
- *
- * `file` is normally the canonical OneBot field and wins, but it can also be a
- * QQ-internal media id (e.g. `<md5>.png`) that this process cannot resolve to a
- * local path. When a bot framework echoes a received image back (Yunzai et al.
- * resend the original `file=<md5>.ext` together with the download `url`), using
- * `file` makes the send path `statSync` the id as a bogus local path and throw
- * `ENOENT`. So: keep `file` when it is a directly loadable source (inline
- * bytes, a remote url, or a filesystem path with a separator); otherwise, if a
- * real http(s) `url` accompanies it, prefer that. (issue #155)
- */
-function pickMediaSource(data: Record<string, unknown>): string {
-  const file = String(data.file ?? '').trim();
-  const url = String(data.url ?? '').trim();
-  const fallback = file || url || String(data.path ?? '').trim() || String(data.media ?? '').trim();
-  if (!file) return fallback;
-  // `file` is itself loadable: inline bytes, a remote url, or a path (anything
-  // carrying a `/` or `\` separator, incl. file:// and absolute/relative paths).
-  if (/^(base64:\/\/|data:|https?:\/\/|file:\/\/)/i.test(file) || /[\\/]/.test(file)) return file;
-  // `file` is a bare token (QQ-internal id) — fall back to a real url if present.
-  if (/^https?:\/\//i.test(url)) return url;
-  return fallback;
-}
-
 // --- JSON segment parsing ---
 
 interface MessageSegment {
@@ -96,130 +50,11 @@ function isSegmentArray(val: unknown): val is MessageSegment[] {
 
 export async function segmentToElement(type: string, data: Record<string, unknown>, options?: ParseMessageOptions): Promise<MessageElement | null> {
   const normalizedType = type.toLowerCase();
+
+  // 纯 OneBot 输入糖：不是某种真实消息元素，只是被塌缩成 json/face/poke 的输入
+  // 便利（或 forward 组装用的中间 node），无收侧对应、无专属 wire 形态，故不进
+  // codec 表 —— 在这里前置处理。真实元素（收发同名）走下方的 ELEMENT_CODECS。
   switch (normalizedType) {
-    case 'text': {
-      const text = String(data.text ?? '');
-      return text ? { type: 'text', text } : null;
-    }
-    case 'face': {
-      const id = intOr(data.id, -1);
-      if (id < 0) return null;
-      return { type: 'face', faceId: id };
-    }
-    case 'at': {
-      const qq = String(data.qq ?? '').trim();
-      if (qq === 'all') {
-        return { type: 'at', targetUin: 0, uid: 'all', text: '@全体成员 ' };
-      }
-      const uin = intOr(qq, 0);
-      if (uin <= 0) return null;
-
-      const name = String(data.name ?? data.nickname ?? data.card ?? '').trim();
-      let uid = String(data.uid ?? '').trim();
-      if (!uid && options?.resolveMentionUid) {
-        uid = (await options.resolveMentionUid(uin))?.trim() ?? '';
-      }
-      const element: MessageElement = { type: 'at', targetUin: uin };
-      if (uid) element.uid = uid;
-      if (name) element.text = `@${name} `;
-      return element;
-    }
-    case 'reply': {
-      const id = intOr(data.id, 0);
-      if (id === 0) return null;
-
-      if (options?.resolveReplySequence) {
-        const resolved = options.resolveReplySequence(id);
-        if (typeof resolved === 'number' && resolved > 0) {
-          const element: MessageElement = {
-            type: 'reply',
-            replySeq: resolved,
-            replyMessageId: id  // Keep the original messageId for logging
-          };
-
-          // Try to get additional meta info for better reply display
-          if (options?.resolveReplyMeta) {
-            const meta = options.resolveReplyMeta(id);
-            if (meta) {
-              element.replySenderUin = meta.senderUin;
-              element.replyTime = meta.time;
-              element.replyRandom = meta.random;
-            }
-          }
-
-          return element;
-        }
-      }
-
-      // Backward-compatible path: allow direct seq reply IDs.
-      return id > 0 ? { type: 'reply', replySeq: id } : null;
-    }
-    case 'image': {
-      // A market face that was surfaced as an `image` (see to-segment) can be
-      // echoed straight back: when `emoji_id` is present we rebuild the market
-      // face instead of re-uploading the gif as a plain picture.
-      const imgEmojiId = String(data.emoji_id ?? '').trim();
-      if (imgEmojiId) return marketFaceElement(imgEmojiId, data);
-      return {
-        type: 'image',
-        url: pickMediaSource(data),
-        flash: data.type === 'flash',
-        subType: intOr(data.subType, 0),
-        summary: data.summary ? String(data.summary) : undefined,
-      };
-    }
-    case 'mface': {
-      // Market face (商城表情). emoji_id is the hex GUID; without it we can't
-      // construct the wire element, so drop the segment.
-      const emojiId = String(data.emoji_id ?? '').trim();
-      if (!emojiId) {
-        log.warn('[MsgParser] mface segment without emoji_id is unsupported');
-        return null;
-      }
-      return marketFaceElement(emojiId, data);
-    }
-    case 'record': {
-      const source = pickMediaSource(data);
-      if (!source) return null;
-      return {
-        type: 'record',
-        url: source,
-      };
-    }
-    case 'video': {
-      const source = pickMediaSource(data);
-      if (!source) return null;
-      return {
-        type: 'video',
-        url: source,
-        thumbUrl: data.thumb ? String(data.thumb) : undefined,
-      };
-    }
-    case 'json': {
-      return {
-        type: 'json',
-        text: String(data.data ?? ''),
-      };
-    }
-    case 'xml': {
-      return {
-        type: 'xml',
-        text: String(data.data ?? ''),
-        subType: intOr(data.id, 0),
-      };
-    }
-    case 'poke': {
-      return {
-        type: 'poke',
-        faceId: intOr(data.type ?? data.id, 0),
-      };
-    }
-    case 'forward': {
-      return {
-        type: 'forward',
-        resId: String(data.id ?? ''),
-      };
-    }
     case 'node': {
       // Fake forward node segment — store the raw data for later processing
       // The content field may be a segment array, a single segment, or a CQ string
@@ -232,12 +67,6 @@ export async function segmentToElement(type: string, data: Record<string, unknow
         resId: JSON.stringify(data.content ?? ''),
       };
     }
-    case 'markdown': {
-      return {
-        type: 'markdown',
-        text: String(data.content ?? ''),
-      };
-    }
     case 'share': {
       // Link share — map to json card message
       const url = String(data.url ?? '');
@@ -349,30 +178,15 @@ export async function segmentToElement(type: string, data: Record<string, unknow
       // Anonymous flag — ignored during send, the protocol handles anonymity
       return null;
     }
-    case 'file': {
-      const fileId = String(data.file_id ?? data.fileId ?? '').trim();
-      const source = String(data.file ?? data.url ?? data.path ?? '').trim();
-      if (!fileId && !source) {
-        log.warn('[MsgParser] file segment without file_id or file/url is unsupported');
-        return null;
-      }
-      const fileName = String(data.name ?? data.filename ?? data.fileName ?? '').trim();
-      const fileSize = intOr(data.size ?? data.fileSize, 0);
-      const md5Hex = String(data.md5 ?? data.md5Hex ?? '').trim();
-      const sha1Hex = String(data.sha1 ?? data.sha1Hex ?? '').trim();
-      const fileHash = String(data.file_hash ?? data.fileHash ?? '').trim();
-      const elem: MessageElement = fileId ? { type: 'file', fileId } : { type: 'file', url: source };
-      if (fileName) elem.fileName = fileName;
-      if (fileSize > 0) elem.fileSize = fileSize;
-      if (md5Hex) elem.md5Hex = md5Hex;
-      if (sha1Hex) elem.sha1Hex = sha1Hex;
-      if (fileHash) elem.fileHash = fileHash;
-      return elem;
-    }
-    default:
-      console.warn(`[MsgParser] unsupported segment type: ${type}`);
-      return null;
   }
+
+  // 真实元素（P 发·解，段 type 与 element.type 同名）：查 codec 表。
+  // 见 event-converter/element-codecs.ts。
+  const codec = ELEMENT_CODECS[normalizedType];
+  if (codec?.fromSegment) return codec.fromSegment(data, options);
+
+  console.warn(`[MsgParser] unsupported segment type: ${type}`);
+  return null;
 }
 
 function segmentPayload(seg: MessageSegment): Record<string, unknown> {
diff --git a/packages/onebot/tests/element-manifest.test.ts b/packages/onebot/tests/element-manifest.test.ts
index b9af9f7e..69ce8f49 100644
--- a/packages/onebot/tests/element-manifest.test.ts
+++ b/packages/onebot/tests/element-manifest.test.ts
@@ -5,46 +5,50 @@ import {
   typesForDirection,
   INPUT_SUGAR_SEGMENTS,
 } from '@snowluma/protocol/element-manifest';
+import { ELEMENT_CODECS } from '../src/event-converter/element-codecs';
 
 // 对账测试（onebot 侧）—— 拿 element-manifest 核对「按 element.type 收敛」的两个
-// onebot 方向：
-//   S 收·转  to-segment.ts 的 `element.type === 'X'` 分支集合
-//   P 发·解  message-parser.ts 的 `case 'X'` 分支集合（剔除纯输入糖）
+// onebot 方向。阶段 2 起这两向已合入 ELEMENT_CODECS 表，故直接用**表的键**核对，
+// 比扫源码正则更硬：
+//   S 收·转  codec.toSegment    MessageElement → OneBot 段
+//   P 发·解  codec.fromSegment  OneBot 段 → MessageElement
 // protocol 侧的 D/W 由 protocol/tests/element-manifest.test.ts 核对（包边界所限）。
 //
-// 架构护栏：谁在这两处增删一种元素方向却没同步 element-manifest，测试当场报红。
-// 纯读源码、零运行时行为改动。
+// 架构护栏：谁在表里增删一个方向却没同步 element-manifest，测试当场报红。
 
-function readSrc(relFromTestDir: string): string {
-  const abs = fileURLToPath(new URL(relFromTestDir, import.meta.url));
-  const raw = readFileSync(abs, 'utf8');
-  return raw.replace(/\/\*[\s\S]*?\*\//g, '').replace(/\/\/.*$/gm, '');
-}
-
-function extractTypes(src: string, pattern: RegExp): string[] {
-  const found = new Set<string>();
-  for (const m of src.matchAll(pattern)) found.add(m[1]!);
-  return [...found].sort();
+function codecTypesWith(dir: 'toSegment' | 'fromSegment'): string[] {
+  return Object.entries(ELEMENT_CODECS)
+    .filter(([, codec]) => typeof codec[dir] === 'function')
+    .map(([type]) => type)
+    .sort();
 }
 
 const sorted = (s: Iterable<string>): string[] => [...s].sort();
 
 describe('element-manifest 对账（onebot 侧：S 收·转 / P 发·解）', () => {
-  it('S：to-segment 的 element.type 分支 == 清单声明的 S=yes', () => {
-    const src = readSrc('../src/event-converter/to-segment.ts');
-    const handled = extractTypes(src, /element\.type\s*===\s*'([A-Za-z0-9_]+)'/g);
-    expect(handled).toEqual(sorted(typesForDirection('S')));
+  it('S：ELEMENT_CODECS 里有 toSegment 的类型 == 清单声明的 S=yes', () => {
+    expect(codecTypesWith('toSegment')).toEqual(sorted(typesForDirection('S')));
   });
 
-  it('P：message-parser 的 case 分支（剔除输入糖）== 清单声明的 P=yes', () => {
-    const src = readSrc('../src/message-parser.ts');
-    // 值域放宽到 `[A-Za-z0-9_]+`：见 protocol/tests/element-manifest.test.ts 同处说明。
-    const allCases = extractTypes(src, /case\s*'([A-Za-z0-9_]+)'\s*:/g);
-    const realElementCases = allCases.filter((t) => !INPUT_SUGAR_SEGMENTS.has(t));
-    expect(realElementCases).toEqual(sorted(typesForDirection('P')));
+  it('P：ELEMENT_CODECS 里有 fromSegment 的类型 == 清单声明的 P=yes', () => {
+    expect(codecTypesWith('fromSegment')).toEqual(sorted(typesForDirection('P')));
+  });
 
-    // 输入糖必须确实出现在 message-parser 里（否则白名单与代码脱节）。
-    const sugarPresent = allCases.filter((t) => INPUT_SUGAR_SEGMENTS.has(t)).sort();
+  it('输入糖仍由 message-parser 前置处理，未被静默丢弃', () => {
+    // 输入糖（骰子/分享/…）不进 codec 表，留在 message-parser 当前置 normalize。
+    // 用源码扫描锁住它们确实存在，防止将来重构时被悄悄删掉。
+    const abs = fileURLToPath(new URL('../src/message-parser.ts', import.meta.url));
+    const src = readFileSync(abs, 'utf8')
+      .replace(/\/\*[\s\S]*?\*\//g, '')
+      .replace(/\/\/.*$/gm, '');
+    const cases = new Set<string>();
+    for (const m of src.matchAll(/case\s*'([A-Za-z0-9_]+)'\s*:/g)) cases.add(m[1]!);
+
+    const sugarPresent = [...cases].filter((t) => INPUT_SUGAR_SEGMENTS.has(t)).sort();
     expect(sugarPresent).toEqual(sorted(INPUT_SUGAR_SEGMENTS));
+
+    // 且 message-parser 不再手写任何真实元素类型的 case（已全部下沉到 codec 表）。
+    const realLeftInParser = [...cases].filter((t) => !INPUT_SUGAR_SEGMENTS.has(t));
+    expect(realLeftInParser).toEqual([]);
   });
 });