diff --git a/migrations/0003_attachment_metadata.sql b/migrations/0003_attachment_metadata.sql
new file mode 100644
index 0000000..9bf7bfa
--- /dev/null
+++ b/migrations/0003_attachment_metadata.sql
@@ -0,0 +1,3 @@
+-- 0003_attachment_metadata.sql — 给附件加结构化、按类型而异的元信息(纯增量)
+ALTER TABLE attachments ADD COLUMN metadata TEXT;      -- 按 kind 判别的 JSON 对象
+ALTER TABLE attachments ADD COLUMN metadata_kind TEXT; -- image|video|audio|document|file,冗余便于筛选
diff --git a/package.json b/package.json
index 53e3597..fe2a2ac 100644
--- a/package.json
+++ b/package.json
@@ -16,6 +16,7 @@
   "dependencies": {
     "@hono/zod-openapi": "^1.4.0",
     "hono": "^4.12.0",
+    "image-size": "^2.0.0",
     "zod": "^4.0.0"
   },
   "devDependencies": {
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index b7c8bca..fad9f9b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -14,6 +14,9 @@ importers:
       hono:
         specifier: ^4.12.0
         version: 4.12.27
+      image-size:
+        specifier: ^2.0.0
+        version: 2.0.2
       zod:
         specifier: ^4.0.0
         version: 4.4.3
@@ -691,6 +694,11 @@ packages:
     resolution: {integrity: sha512-1yrb/+w6HWQJrUCLkJ2IF5jNIPvvFkblV5RNOYl6bV+OA6p9GLcMpHFFGTosSvHvcAUibuUukRqhlYI4z32C7Q==}
     engines: {node: '>=16.9.0'}
 
+  image-size@2.0.2:
+    resolution: {integrity: sha512-IRqXKlaXwgSMAMtpNzZa1ZAe8m+Sa1770Dhk8VkSsP9LS+iHD62Zd8FQKs8fbPiagBE7BzoFX23cxFnwshpV6w==}
+    engines: {node: '>=16.x'}
+    hasBin: true
+
   js-tokens@9.0.1:
     resolution: {integrity: sha512-mxa9E9ITFOt0ban3j6L5MpjwegGz6lBQmM1IJkWeBZGcMxto50+eWdjC/52xDbS2vy0k7vIMK0Fe2wfL9OQSpQ==}
 
@@ -1384,6 +1392,8 @@ snapshots:
 
   hono@4.12.27: {}
 
+  image-size@2.0.2: {}
+
   js-tokens@9.0.1: {}
 
   kleur@4.1.5: {}