diff --git a/dashboard/package.json b/dashboard/package.json
index 81a353bf2d..172791fc02 100644
--- a/dashboard/package.json
+++ b/dashboard/package.json
@@ -35,6 +35,7 @@
     "markstream-vue": "1.0.5-beta.0",
     "mermaid": "^11.12.2",
     "monaco-editor": "^0.52.2",
+    "pdfjs-dist": "6.3.289",
     "pinia": "2.1.6",
     "pinyin-pro": "^3.26.0",
     "qrcode": "^1.5.4",
diff --git a/dashboard/pnpm-lock.yaml b/dashboard/pnpm-lock.yaml
index cae4d6bc12..ff1ab0450b 100644
--- a/dashboard/pnpm-lock.yaml
+++ b/dashboard/pnpm-lock.yaml
@@ -69,6 +69,9 @@ importers:
       monaco-editor:
         specifier: ^0.52.2
         version: 0.52.2
+      pdfjs-dist:
+        specifier: 6.3.289
+        version: 6.3.289
       pinia:
         specifier: 2.1.6
         version: 2.1.6(typescript@5.1.6)(vue@3.3.4)
@@ -518,6 +521,81 @@ packages:
   '@monaco-editor/loader@1.7.0':
     resolution: {integrity: sha512-gIwR1HrJrrx+vfyOhYmCZ0/JcWqG5kbfG7+d3f/C1LXk2EvzAbHSg3MQ5lO2sMlo9izoAZ04shohfKLVT6crVA==}
 
+  '@napi-rs/canvas-android-arm64@1.0.9':
+    resolution: {integrity: sha512-4LGXk2/0HVzE29K8SzML5WubgCp++B1FH3qgl35XmSZE+lLdr6P9VRQEnZ0MCLZMTSuJP41yyhtoiVNEuvrTIA==}
+    engines: {node: '>= 10'}
+    cpu: [arm64]
+    os: [android]
+
+  '@napi-rs/canvas-darwin-arm64@1.0.9':
+    resolution: {integrity: sha512-YNdfLBzY0W/Pep9fo2L6RmoNlNksnn05LRnX66W63R3ij58S25QOTcjdtEt2v8+PnCESzqZsYzUo+QPeIR44NA==}
+    engines: {node: '>= 10'}
+    cpu: [arm64]
+    os: [darwin]
+
+  '@napi-rs/canvas-darwin-x64@1.0.9':
+    resolution: {integrity: sha512-ceZQSknTEcy3dOXoekv59LTCkXjvnLsq+VW5PeNNDHEPQbRS5Ervkm1EaDa7WLAjiYWMLuSQTRTHao1dEX4prg==}
+    engines: {node: '>= 10'}
+    cpu: [x64]
+    os: [darwin]
+
+  '@napi-rs/canvas-linux-arm-gnueabihf@1.0.9':
+    resolution: {integrity: sha512-XhfI0Wwv4llhd6nnWDtY3kQKjq0r+y1i91PlJlJI24ag2U9WrnwbG1qS3+fDLEyouwEVFchiKkTEHozK+5iUNA==}
+    engines: {node: '>= 10'}
+    cpu: [arm]
+    os: [linux]
+
+  '@napi-rs/canvas-linux-arm64-gnu@1.0.9':
+    resolution: {integrity: sha512-012oiYtKaE7i9oxc8q7nraT7kDOpLcaCmFLzVe9Ty34RHDdoDzbWLrVh827CNxYh/EADX1eSikA3ymLjo/nNuw==}
+    engines: {node: '>= 10'}
+    cpu: [arm64]
+    os: [linux]
+    libc: [glibc]
+
+  '@napi-rs/canvas-linux-arm64-musl@1.0.9':
+    resolution: {integrity: sha512-Ls5UWYFFn63casTZEczbeyEg3vRDRkv9lscuGwfchtY5yLLQhgOB8SN4YGxmfJ5vTaBwZ2YUxBS3NtmjJmFXdA==}
+    engines: {node: '>= 10'}
+    cpu: [arm64]
+    os: [linux]
+    libc: [musl]
+
+  '@napi-rs/canvas-linux-riscv64-gnu@1.0.9':
+    resolution: {integrity: sha512-hLKEGxV7ZiRHqndePTokgDMdBlo/rDfzg7P4p4QIv9pUhuYobnu3R2NIFLCRghG0nwfo+s2sw+c1xZFeCmEAsw==}
+    engines: {node: '>= 10'}
+    cpu: [riscv64]
+    os: [linux]
+    libc: [glibc]
+
+  '@napi-rs/canvas-linux-x64-gnu@1.0.9':
+    resolution: {integrity: sha512-6kaz3w0QMy77PDWk6rJ1ksIihdad3qzEyX2o2oGT8GwCaypfT5mhjr8buOO5hstyLxcWXDScuz56RsINLtBPIQ==}
+    engines: {node: '>= 10'}
+    cpu: [x64]
+    os: [linux]
+    libc: [glibc]
+
+  '@napi-rs/canvas-linux-x64-musl@1.0.9':
+    resolution: {integrity: sha512-xrGvmS3v55hmZ86ls/kBLVNMUTYio3f6Ik0DireemG994VfPAwiA3ZXA0Uf1bByctkB3NQ1Sfb+H5bkdUnnzfQ==}
+    engines: {node: '>= 10'}
+    cpu: [x64]
+    os: [linux]
+    libc: [musl]
+
+  '@napi-rs/canvas-win32-arm64-msvc@1.0.9':
+    resolution: {integrity: sha512-yjmVS3ArZeRVCP7jqbPq4rpZa/BhTeI7ELE2XqJg3snICQBDevLZyArxswHkiTnT34KRic33/4fLirrHI+SY8A==}
+    engines: {node: '>= 10'}
+    cpu: [arm64]
+    os: [win32]
+
+  '@napi-rs/canvas-win32-x64-msvc@1.0.9':
+    resolution: {integrity: sha512-QlSYQdMQslB81nlABo9wNfQ6npFhE7/O+saCZdqVGueGanyRk4jCogD5EwQenfP3kIq9e+mm6GreQBjX5MrA8g==}
+    engines: {node: '>= 10'}
+    cpu: [x64]
+    os: [win32]
+
+  '@napi-rs/canvas@1.0.9':
+    resolution: {integrity: sha512-QviPdJImDi/jMAvBfqaw+19BndMd/sizXVW3NnpMd3VJGz++QXkOHcP9kWR/smHG0hNjHeyuHFyrx/5lD0oNcQ==}
+    engines: {node: '>= 10'}
+
   '@nodelib/fs.scandir@2.1.5':
     resolution: {integrity: sha512-vq24Bq3ym5HEQm2NKCr3yXDwjc7vTsEThRDnkp2DK9p1uqLR+DHurm/NOTo0KG7HYHU7eppKZj3MyqYuMBf62g==}
     engines: {node: '>= 8'}
@@ -2451,6 +2529,10 @@ packages:
   pathe@2.0.3:
     resolution: {integrity: sha512-WUjGcAqP1gQacoQe+OBJsFA7Ld4DyXuUIjZ5cc75cLHvJ7dtNsTugphxIADwspS+AraAUePCKrSVtPLFj/F88w==}
 
+  pdfjs-dist@6.3.289:
+    resolution: {integrity: sha512-ZHjSVpDa3D6izMq8/04lvkhkATUmL9px6ChPaXc1k6nU2Mrhlg1/7F0bdUqCwUjw3NsPTfPZsMDUU6ZIcRaeQw==}
+    engines: {node: '>=22.13.0 || >=24'}
+
   perfect-debounce@1.0.0:
     resolution: {integrity: sha512-xCy9V055GLEqoFaHoC1SoLIaLmWctgCUaBaWxDZ7/Zx4CTyX7cJQLJOok/orfjZAh9kEYpjJa4d0KcJmCbctZA==}
 
@@ -3518,6 +3600,54 @@ snapshots:
     dependencies:
       state-local: 1.0.7
 
+  '@napi-rs/canvas-android-arm64@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-darwin-arm64@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-darwin-x64@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-arm-gnueabihf@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-arm64-gnu@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-arm64-musl@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-riscv64-gnu@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-x64-gnu@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-linux-x64-musl@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-win32-arm64-msvc@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas-win32-x64-msvc@1.0.9':
+    optional: true
+
+  '@napi-rs/canvas@1.0.9':
+    optionalDependencies:
+      '@napi-rs/canvas-android-arm64': 1.0.9
+      '@napi-rs/canvas-darwin-arm64': 1.0.9
+      '@napi-rs/canvas-darwin-x64': 1.0.9
+      '@napi-rs/canvas-linux-arm-gnueabihf': 1.0.9
+      '@napi-rs/canvas-linux-arm64-gnu': 1.0.9
+      '@napi-rs/canvas-linux-arm64-musl': 1.0.9
+      '@napi-rs/canvas-linux-riscv64-gnu': 1.0.9
+      '@napi-rs/canvas-linux-x64-gnu': 1.0.9
+      '@napi-rs/canvas-linux-x64-musl': 1.0.9
+      '@napi-rs/canvas-win32-arm64-msvc': 1.0.9
+      '@napi-rs/canvas-win32-x64-msvc': 1.0.9
+    optional: true
+
   '@nodelib/fs.scandir@2.1.5':
     dependencies:
       '@nodelib/fs.stat': 2.0.5
@@ -5594,6 +5724,10 @@ snapshots:
 
   pathe@2.0.3: {}
 
+  pdfjs-dist@6.3.289:
+    optionalDependencies:
+      '@napi-rs/canvas': 1.0.9
+
   perfect-debounce@1.0.0: {}
 
   picocolors@1.1.1: {}
diff --git a/dashboard/scripts/pdfjs-assets.mjs b/dashboard/scripts/pdfjs-assets.mjs
new file mode 100644
index 0000000000..ba80e66df4
--- /dev/null
+++ b/dashboard/scripts/pdfjs-assets.mjs
@@ -0,0 +1,56 @@
+import { readFileSync, readdirSync } from "node:fs";
+import { createRequire } from "node:module";
+import { dirname, join } from "node:path";
+
+const require = createRequire(import.meta.url);
+const packagePath = require.resolve("pdfjs-dist/package.json");
+const root = dirname(packagePath);
+const { version } = JSON.parse(readFileSync(packagePath, "utf8"));
+
+/** Serve the same versioned PDF resources in development and production. */
+export function pdfjsAssets() {
+  const files = new Map([["LICENSE", join(root, "LICENSE")]]);
+  for (const directory of ["cmaps", "standard_fonts", "wasm", "iccs"]) {
+    for (const entry of readdirSync(join(root, directory), {
+      withFileTypes: true,
+    })) {
+      if (entry.isFile()) {
+        files.set(
+          `${directory}/${entry.name}`,
+          join(root, directory, entry.name),
+        );
+      }
+    }
+  }
+  return {
+    name: "pdfjs-assets",
+    configureServer(server) {
+      server.middlewares.use(
+        `${server.config.base}pdfjs/${version}/`,
+        (req, res, next) => {
+          const name = req.url?.split("?")[0].replace(/^\//, "");
+          const file = files.get(name);
+          if (!file) return next();
+          res.setHeader(
+            "Content-Type",
+            name.endsWith(".wasm")
+              ? "application/wasm"
+              : /\.m?js$/.test(name)
+              ? "text/javascript"
+              : "application/octet-stream",
+          );
+          res.end(readFileSync(file));
+        },
+      );
+    },
+    generateBundle() {
+      for (const [name, file] of files) {
+        this.emitFile({
+          type: "asset",
+          fileName: `pdfjs/${version}/${name}`,
+          source: readFileSync(file),
+        });
+      }
+    },
+  };
+}
diff --git a/dashboard/src/api/v1.ts b/dashboard/src/api/v1.ts
index 709d4060a7..158d8fdd9d 100644
--- a/dashboard/src/api/v1.ts
+++ b/dashboard/src/api/v1.ts
@@ -944,11 +944,12 @@ export const chatApi = {
       }),
     );
   },
-  downloadProjectWorkspaceFile(projectId: string, path: string) {
+  downloadProjectWorkspaceFile(projectId: string, path: string, signal?: AbortSignal) {
     return openApiV1.downloadChatProjectWorkspaceFile({
       path: { project_id: projectId },
       query: { path },
       responseType: 'blob',
+      signal,
     }) as Promise<AxiosResponse<Blob>>;
   },
   addProjectSession(projectId: string, sessionId: string) {
diff --git a/dashboard/src/components/chat/WorkspaceFilesPanel.vue b/dashboard/src/components/chat/WorkspaceFilesPanel.vue
index baeafb1286..b34884ca88 100644
--- a/dashboard/src/components/chat/WorkspaceFilesPanel.vue
+++ b/dashboard/src/components/chat/WorkspaceFilesPanel.vue
@@ -1,203 +1,366 @@
 <template>
   <transition name="chat-panel">
-    <aside v-if="modelValue" class="workspace-files-panel chat-side-panel">
-      <div class="workspace-toolbar">
-        <div class="workspace-filter">
-          <Search :size="17" />
-          <input
-            v-model="filterQuery"
-            type="search"
-            :placeholder="tm('workspaceFiles.filter')"
-          />
+    <aside
+      v-if="modelValue"
+      class="workspace-files-panel chat-side-panel"
+      :class="{ 'has-preview': openFiles.length }"
+      :aria-label="tm('workspaceFiles.title')"
+    >
+      <header class="workspace-tabs-header">
+        <div
+          ref="tabList"
+          class="workspace-tabs"
+          role="tablist"
+          :aria-label="tm('workspaceFiles.openTabs')"
+          @keydown="handleTabKeydown"
+        >
           <button
-            v-if="filterQuery"
+            class="workspace-tab workspace-files-tab"
             type="button"
-            :aria-label="tm('workspaceFiles.clearFilter')"
-            @click="filterQuery = ''"
+            role="tab"
+            :aria-selected="!selectedFilePath"
+            :tabindex="selectedFilePath ? -1 : 0"
+            @click="
+              clearPreview();
+              treeCollapsed = false;
+            "
           >
-            <X :size="15" />
+            <FolderOpen :size="16" />
+            <span>{{ tm("workspaceFiles.title") }}</span>
           </button>
+          <div
+            v-for="file in openFiles"
+            :key="file.path"
+            class="workspace-file-tab"
+            :class="{
+              active: selectedFilePath === file.path,
+              'is-preview': previewFilePath === file.path,
+            }"
+          >
+            <button
+              class="workspace-tab"
+              type="button"
+              role="tab"
+              :title="file.path"
+              :aria-selected="selectedFilePath === file.path"
+              :tabindex="selectedFilePath === file.path ? 0 : -1"
+              @click="openEntry(file)"
+              @dblclick="pinPreview(file.path)"
+            >
+              <FileText :size="15" />
+              <span>{{ file.name }}</span>
+            </button>
+            <button
+              type="button"
+              class="workspace-tab-close"
+              :aria-label="tm('workspaceFiles.closeTab', { name: file.name })"
+              @click="closeFile(file.path)"
+            >
+              <X :size="13" />
+            </button>
+          </div>
+        </div>
+        <v-btn
+          icon
+          size="x-small"
+          variant="text"
+          :title="tm('workspaceFiles.close')"
+          :aria-label="tm('workspaceFiles.close')"
+          @click="close"
+          ><X :size="17"
+        /></v-btn>
+      </header>
+
+      <div class="workspace-path-bar">
+        <div
+          class="workspace-breadcrumbs"
+          :title="selectedFilePath || projectTitle"
+        >
+          <span v-if="projectTitle" class="workspace-project-name">{{
+            projectTitle
+          }}</span>
+          <template
+            v-for="(part, index) in selectedFilePath.split('/').filter(Boolean)"
+            :key="index"
+          >
+            <ChevronRight v-if="projectTitle || index" :size="12" />
+            <span
+              :class="{
+                'is-filename': index === selectedFilePath.split('/').length - 1,
+              }"
+              >{{ part }}</span
+            >
+          </template>
         </div>
-        <div class="workspace-files-actions">
+        <div class="workspace-preview-actions">
           <v-btn
+            v-if="selectedFilePath"
             icon
-            size="small"
+            size="x-small"
             variant="text"
-            :title="tm('workspaceFiles.refresh')"
-            :loading="rootLoading"
-            @click="refreshTree"
-          >
-            <RotateCw :size="17" />
-          </v-btn>
+            :loading="fileDownloading"
+            :title="tm('workspaceFiles.download')"
+            :aria-label="tm('workspaceFiles.download')"
+            @click="downloadSelectedFile"
+            ><Download :size="16"
+          /></v-btn>
+          <v-btn
+            v-if="selectedFilePath"
+            icon
+            size="x-small"
+            variant="text"
+            :title="tm('workspaceFiles.dialogPreview')"
+            :aria-label="tm('workspaceFiles.dialogPreview')"
+            @click="
+              pinPreview();
+              previewDialog = true;
+            "
+            ><Maximize2 :size="15"
+          /></v-btn>
           <v-btn
+            v-if="openFiles.length"
             icon
-            size="small"
+            size="x-small"
             variant="text"
-            :title="tm('workspaceFiles.close')"
-            @click="close"
+            :aria-expanded="!treeCollapsed"
+            :title="
+              tm(
+                treeCollapsed
+                  ? 'workspaceFiles.showTree'
+                  : 'workspaceFiles.hideTree',
+              )
+            "
+            :aria-label="
+              tm(
+                treeCollapsed
+                  ? 'workspaceFiles.showTree'
+                  : 'workspaceFiles.hideTree',
+              )
+            "
+            @click="treeCollapsed = !treeCollapsed"
           >
-            <X :size="18" />
+            <PanelRightOpen v-if="treeCollapsed" :size="17" /><PanelRightClose
+              v-else
+              :size="17"
+            />
           </v-btn>
         </div>
       </div>
 
-      <v-alert
-        v-if="treeError"
-        class="workspace-error"
-        density="compact"
-        type="error"
-        variant="tonal"
-      >
-        {{ treeError }}
-      </v-alert>
-
-      <div
-        class="workspace-tree"
-        :class="{ 'workspace-tree--with-preview': selectedFilePath }"
-      >
-        <div v-if="rootLoading && !rootEntries.length" class="workspace-state">
-          <v-progress-circular indeterminate size="24" width="2" />
-        </div>
-        <div v-else-if="!visibleEntries.length" class="workspace-state">
-          {{
-            filterQuery
-              ? tm("workspaceFiles.noMatches")
-              : tm("workspaceFiles.empty")
-          }}
-        </div>
-        <template v-else>
-          <button
-            v-for="{ entry, depth } in visibleEntries"
-            :key="entry.path"
-            class="workspace-tree-row"
-            :class="{
-              'workspace-tree-row--active': selectedFilePath === entry.path,
-            }"
-            :style="{ paddingLeft: `${10 + depth * 18}px` }"
-            type="button"
-            :title="entry.path"
-            @click="openEntry(entry)"
+      <div class="workspace-body">
+        <section
+          v-if="openFiles.length"
+          class="workspace-preview"
+          role="tabpanel"
+          tabindex="0"
+          :aria-label="selectedFilePath || tm('workspaceFiles.title')"
+          @pointerdown="pinPreview()"
+          @wheel.passive="pinPreview()"
+          @keydown="pinPreview()"
+        >
+          <div v-if="!selectedFilePath" class="workspace-preview-empty">
+            <Files :size="32" :stroke-width="1.25" />
+            <span>{{ tm("workspaceFiles.selectFile") }}</span>
+          </div>
+          <div v-else-if="fileLoading" class="workspace-preview-state">
+            <v-progress-circular indeterminate size="24" width="2" />
+          </div>
+          <div
+            v-else-if="fileError"
+            class="workspace-preview-state"
+            role="alert"
           >
-            <span class="workspace-tree-chevron">
-              <v-progress-circular
-                v-if="entry.loading"
-                indeterminate
-                size="14"
-                width="2"
-              />
-              <ChevronDown
-                v-else-if="entry.type === 'directory' && entry.expanded"
-                :size="16"
-              />
-              <ChevronRight v-else-if="entry.type === 'directory'" :size="16" />
-            </span>
-            <FolderOpen
-              v-if="entry.type === 'directory' && entry.expanded"
-              :size="17"
-              class="workspace-folder-icon"
-            />
-            <Folder
-              v-else-if="entry.type === 'directory'"
-              :size="17"
-              class="workspace-folder-icon"
-            />
-            <FileText v-else :size="16" class="workspace-file-icon" />
-            <span class="workspace-tree-name">{{ entry.name }}</span>
-            <span v-if="entry.type === 'file'" class="workspace-tree-size">
-              {{ formatSize(entry.size) }}
-            </span>
-          </button>
-        </template>
-      </div>
-
-      <section v-if="selectedFilePath" class="workspace-preview">
-        <header class="workspace-preview-header">
-          <div class="workspace-preview-path" :title="selectedFilePath">
-            {{ selectedFilePath }}
+            {{ fileError }}
           </div>
-          <div class="workspace-preview-actions">
-            <v-btn
-              icon
-              size="x-small"
-              variant="text"
-              :title="tm('workspaceFiles.download')"
-              :loading="fileDownloading"
-              @click="downloadSelectedFile"
-            >
-              <Download :size="16" />
-            </v-btn>
-            <v-btn
-              icon
-              size="x-small"
-              variant="text"
-              :title="tm('workspaceFiles.dialogPreview')"
-              @click="previewDialog = true"
-            >
-              <Maximize2 :size="15" />
-            </v-btn>
+          <WorkspacePdfPreview
+            v-else-if="pdfFile && !previewDialog"
+            v-model:page="pdfPage"
+            v-model:zoom="pdfZoom"
+            :file="pdfFile"
+          />
+          <div v-else-if="!pdfFile" class="workspace-code-view">
+            <pre class="workspace-line-numbers" aria-hidden="true">{{
+              lineNumbers
+            }}</pre>
+            <pre
+              class="workspace-preview-content"
+            ><code>{{ fileContent }}</code></pre>
+          </div>
+        </section>
+
+        <button
+          v-if="openFiles.length && !treeCollapsed"
+          class="workspace-tree-scrim"
+          type="button"
+          :aria-label="tm('workspaceFiles.hideTree')"
+          @click="treeCollapsed = true"
+        />
+        <section
+          v-show="!treeCollapsed || !openFiles.length"
+          class="workspace-tree-pane"
+          :aria-label="tm('workspaceFiles.title')"
+        >
+          <div class="workspace-tree-toolbar">
+            <div class="workspace-filter">
+              <Search :size="15" />
+              <input
+                v-model="filterQuery"
+                type="search"
+                :placeholder="tm('workspaceFiles.filter')"
+                :aria-label="tm('workspaceFiles.filter')"
+              />
+              <button
+                v-if="filterQuery"
+                type="button"
+                :aria-label="tm('workspaceFiles.clearFilter')"
+                @click="filterQuery = ''"
+              >
+                <X :size="13" />
+              </button>
+            </div>
             <v-btn
               icon
               size="x-small"
               variant="text"
-              :title="tm('workspaceFiles.closePreview')"
-              @click="clearPreview"
+              :loading="rootLoading"
+              :title="tm('workspaceFiles.refresh')"
+              :aria-label="tm('workspaceFiles.refresh')"
+              @click="refreshTree"
+              ><RotateCw :size="15"
+            /></v-btn>
+          </div>
+          <v-alert
+            v-if="treeError"
+            class="workspace-error"
+            density="compact"
+            type="error"
+            variant="tonal"
+            >{{ treeError }}</v-alert
+          >
+          <div class="workspace-tree">
+            <div
+              v-if="rootLoading && !rootEntries.length"
+              class="workspace-state"
             >
-              <X :size="16" />
-            </v-btn>
+              <v-progress-circular indeterminate size="24" width="2" />
+            </div>
+            <div v-else-if="!visibleEntries.length" class="workspace-state">
+              {{
+                filterQuery
+                  ? tm("workspaceFiles.noMatches")
+                  : tm("workspaceFiles.empty")
+              }}
+            </div>
+            <template v-else>
+              <button
+                v-for="{ entry, depth } in visibleEntries"
+                :key="entry.path"
+                class="workspace-tree-row"
+                :class="{
+                  'workspace-tree-row--active': selectedFilePath === entry.path,
+                }"
+                :style="{ paddingLeft: `${8 + depth * 16}px` }"
+                type="button"
+                :title="entry.path"
+                :aria-expanded="
+                  entry.type === 'directory'
+                    ? Boolean(entry.expanded)
+                    : undefined
+                "
+                @click="openEntry(entry)"
+                @dblclick="entry.type === 'file' && pinPreview(entry.path)"
+              >
+                <span class="workspace-tree-chevron">
+                  <v-progress-circular
+                    v-if="entry.loading"
+                    indeterminate
+                    size="13"
+                    width="2"
+                  />
+                  <ChevronDown
+                    v-else-if="entry.type === 'directory' && entry.expanded"
+                    :size="14"
+                  />
+                  <ChevronRight
+                    v-else-if="entry.type === 'directory'"
+                    :size="14"
+                  />
+                </span>
+                <FolderOpen
+                  v-if="entry.type === 'directory' && entry.expanded"
+                  :size="16"
+                  class="workspace-folder-icon"
+                />
+                <Folder
+                  v-else-if="entry.type === 'directory'"
+                  :size="16"
+                  class="workspace-folder-icon"
+                />
+                <FileText v-else :size="15" class="workspace-file-icon" />
+                <span class="workspace-tree-name">{{ entry.name }}</span>
+                <span
+                  v-if="entry.type === 'file'"
+                  class="workspace-tree-size"
+                  >{{ formatSize(entry.size) }}</span
+                >
+              </button>
+            </template>
           </div>
-        </header>
-        <div v-if="fileLoading" class="workspace-preview-state">
-          <v-progress-circular indeterminate size="24" width="2" />
-        </div>
-        <div v-else-if="fileError" class="workspace-preview-state">
-          {{ fileError }}
-        </div>
-        <pre
-          v-else
-          class="workspace-preview-content"
-        ><code>{{ fileContent }}</code></pre>
-      </section>
+        </section>
+      </div>
 
       <v-dialog
         v-model="previewDialog"
-        max-width="1000"
+        max-width="1200"
         width="calc(100% - 32px)"
       >
         <v-card class="workspace-dialog-preview">
-          <header class="workspace-dialog-preview-header">
-            <div class="workspace-preview-path" :title="selectedFilePath">
-              {{ selectedFilePath }}
-            </div>
+          <v-card-title
+            class="text-h3 pa-4 pb-0 pl-6 workspace-dialog-preview-header"
+          >
+            <span class="workspace-preview-path" :title="selectedFilePath">{{
+              selectedFilePath.split("/").pop()
+            }}</span>
             <div class="workspace-preview-actions">
               <v-btn
                 icon
                 variant="text"
                 :title="tm('workspaceFiles.download')"
+                :aria-label="tm('workspaceFiles.download')"
                 :loading="fileDownloading"
                 @click="downloadSelectedFile"
-              >
-                <Download :size="18" />
-              </v-btn>
+                ><Download :size="18"
+              /></v-btn>
               <v-btn
                 icon
                 variant="text"
                 :title="tm('workspaceFiles.closeDialogPreview')"
+                :aria-label="tm('workspaceFiles.closeDialogPreview')"
                 @click="previewDialog = false"
-              >
-                <X :size="20" />
-              </v-btn>
+                ><X :size="20"
+              /></v-btn>
             </div>
-          </header>
+          </v-card-title>
           <div v-if="fileLoading" class="workspace-preview-state">
             <v-progress-circular indeterminate size="28" width="2" />
           </div>
           <div v-else-if="fileError" class="workspace-preview-state">
             {{ fileError }}
           </div>
-          <pre
-            v-else
-            class="workspace-preview-content workspace-dialog-preview-content"
-          ><code>{{ fileContent }}</code></pre>
+          <WorkspacePdfPreview
+            v-else-if="pdfFile && previewDialog"
+            v-model:page="pdfPage"
+            v-model:zoom="pdfZoom"
+            :file="pdfFile"
+          />
+          <div v-else-if="!pdfFile" class="workspace-code-view">
+            <pre class="workspace-line-numbers" aria-hidden="true">{{
+              lineNumbers
+            }}</pre>
+            <pre
+              class="workspace-preview-content"
+            ><code>{{ fileContent }}</code></pre>
+          </div>
         </v-card>
       </v-dialog>
     </aside>
@@ -206,15 +369,26 @@
 
 <script setup lang="ts">
 import "@/components/chat/chatPanelTransition.css";
-import { computed, ref, watch } from "vue";
+import {
+  computed,
+  defineAsyncComponent,
+  nextTick,
+  onBeforeUnmount,
+  ref,
+  shallowRef,
+  watch,
+} from "vue";
 import {
   ChevronDown,
   ChevronRight,
   Download,
   FileText,
+  Files,
   Folder,
   FolderOpen,
   Maximize2,
+  PanelRightClose,
+  PanelRightOpen,
   RotateCw,
   Search,
   X,
@@ -222,6 +396,11 @@ import {
 import { chatApi } from "@/api/v1";
 import { useModuleI18n } from "@/i18n/composables";
 
+const WorkspacePdfPreview = defineAsyncComponent(
+  () => import("./WorkspacePdfPreview.vue"),
+);
+const PDF_PREVIEW_MAX_BYTES = 50 * 1024 * 1024;
+
 interface WorkspaceEntry {
   name: string;
   path: string;
@@ -250,7 +429,21 @@ const rootLoading = ref(false);
 const treeError = ref("");
 const filterQuery = ref("");
 const selectedFilePath = ref("");
+const openFiles = ref<WorkspaceEntry[]>([]);
+const previewFilePath = ref("");
+const tabList = ref<HTMLElement | null>(null);
+const treeCollapsed = ref(false);
 const fileContent = ref("");
+const lineNumbers = computed(() =>
+  fileContent.value
+    .split("\n")
+    .map((_, index) => index + 1)
+    .join("\n"),
+);
+const pdfFile = shallowRef<Blob | null>(null);
+const pdfPage = ref(1);
+const pdfZoom = ref(1);
+let fileAbort: AbortController | undefined;
 const fileLoading = ref(false);
 const fileError = ref("");
 const fileDownloading = ref(false);
@@ -284,7 +477,13 @@ const visibleEntries = computed(() => {
 watch(
   () => [props.modelValue, props.projectId] as const,
   async ([open, projectId], previous) => {
-    if (!open || !projectId) return;
+    if (!open || !projectId) {
+      clearPreview();
+      openFiles.value = [];
+      previewFilePath.value = "";
+      treeCollapsed.value = false;
+      return;
+    }
     const previousProjectId = previous?.[1];
     if (
       projectId !== previousProjectId ||
@@ -297,6 +496,8 @@ watch(
   { immediate: true },
 );
 
+onBeforeUnmount(clearPreview);
+
 function close() {
   emit("update:modelValue", false);
 }
@@ -308,20 +509,68 @@ function resetPanel() {
   rootLoading.value = false;
   treeError.value = "";
   filterQuery.value = "";
+  openFiles.value = [];
+  previewFilePath.value = "";
+  treeCollapsed.value = false;
   clearPreview();
 }
 
+function pinPreview(path = selectedFilePath.value) {
+  if (previewFilePath.value === path) previewFilePath.value = "";
+}
+
+async function closeFile(path: string) {
+  const index = openFiles.value.findIndex((file) => file.path === path);
+  if (index < 0) return;
+  openFiles.value.splice(index, 1);
+  if (previewFilePath.value === path) previewFilePath.value = "";
+  if (selectedFilePath.value === path) {
+    const next = openFiles.value[Math.min(index, openFiles.value.length - 1)];
+    if (next) await openEntry(next);
+    else clearPreview();
+  }
+  if (!openFiles.value.length) treeCollapsed.value = false;
+}
+
+function handleTabKeydown(event: KeyboardEvent) {
+  if ((event.target as HTMLElement).getAttribute("role") !== "tab") return;
+  const tabs = Array.from(
+    (event.currentTarget as HTMLElement).querySelectorAll<HTMLButtonElement>(
+      '[role="tab"]',
+    ),
+  );
+  const current = tabs.indexOf(event.target as HTMLButtonElement);
+  let index = current;
+  if (event.key === "ArrowRight") index = (current + 1) % tabs.length;
+  else if (event.key === "ArrowLeft")
+    index = (current - 1 + tabs.length) % tabs.length;
+  else if (event.key === "Home") index = 0;
+  else if (event.key === "End") index = tabs.length - 1;
+  else return;
+  event.preventDefault();
+  tabs[index]?.focus();
+  tabs[index]?.click();
+}
+
 function clearPreview() {
+  fileAbort?.abort();
+  fileAbort = undefined;
   fileGeneration.value += 1;
   previewDialog.value = false;
   selectedFilePath.value = "";
   fileContent.value = "";
+  pdfFile.value = null;
+  pdfPage.value = 1;
+  pdfZoom.value = 1;
   fileError.value = "";
   fileLoading.value = false;
 }
 
 async function refreshTree() {
-  resetPanel();
+  treeGeneration.value += 1;
+  rootEntries.value = [];
+  rootLoading.value = false;
+  treeError.value = "";
   if (props.projectId) {
     await loadDirectory("");
   }
@@ -387,20 +636,52 @@ async function openEntry(entry: WorkspaceEntry) {
     return;
   }
 
+  if (selectedFilePath.value === entry.path && !fileError.value) return;
+  if (!openFiles.value.some((file) => file.path === entry.path)) {
+    const previewIndex = openFiles.value.findIndex(
+      (file) => file.path === previewFilePath.value,
+    );
+    if (previewIndex >= 0)
+      openFiles.value.splice(previewIndex, 1, { ...entry });
+    else openFiles.value.push({ ...entry });
+    previewFilePath.value = entry.path;
+  }
+  clearPreview();
   selectedFilePath.value = entry.path;
-  fileContent.value = "";
-  fileError.value = "";
-  fileLoading.value = false;
-  fileGeneration.value += 1;
+  if (window.matchMedia("(max-width: 760px)").matches)
+    treeCollapsed.value = true;
+  void nextTick(() => {
+    tabList.value
+      ?.querySelector('[role="tab"][aria-selected="true"]')
+      ?.scrollIntoView({ block: "nearest", inline: "nearest" });
+  });
   const generation = fileGeneration.value;
   const projectId = props.projectId;
-  if (!entry.readable) {
-    fileError.value = tm("workspaceFiles.tooLarge");
+  const isPdf = entry.path.toLowerCase().endsWith(".pdf");
+  if (isPdf ? entry.size > PDF_PREVIEW_MAX_BYTES : !entry.readable) {
+    fileError.value = tm(
+      isPdf ? "workspaceFiles.pdf.tooLarge" : "workspaceFiles.tooLarge",
+    );
     return;
   }
 
   fileLoading.value = true;
   try {
+    if (isPdf) {
+      fileAbort = new AbortController();
+      const response = await chatApi.downloadProjectWorkspaceFile(
+        projectId,
+        entry.path,
+        fileAbort.signal,
+      );
+      if (generation !== fileGeneration.value || projectId !== props.projectId)
+        return;
+      if (response.data.size > PDF_PREVIEW_MAX_BYTES) {
+        throw new Error(tm("workspaceFiles.pdf.tooLarge"));
+      }
+      pdfFile.value = response.data;
+      return;
+    }
     const response = await chatApi.getProjectWorkspaceFile(
       projectId,
       entry.path,
@@ -433,22 +714,27 @@ async function downloadSelectedFile() {
   if (!props.projectId || !selectedFilePath.value || fileDownloading.value) {
     return;
   }
+  pinPreview();
+  const projectId = props.projectId;
+  const path = selectedFilePath.value;
   fileDownloading.value = true;
   try {
     const response = await chatApi.downloadProjectWorkspaceFile(
-      props.projectId,
-      selectedFilePath.value,
+      projectId,
+      path,
     );
     const url = URL.createObjectURL(response.data);
     const anchor = document.createElement("a");
     anchor.href = url;
-    anchor.download = selectedFilePath.value.split("/").pop() || "download";
+    anchor.download = path.split("/").pop() || "download";
     document.body.appendChild(anchor);
     anchor.click();
     anchor.remove();
     setTimeout(() => URL.revokeObjectURL(url), 0);
   } catch {
-    fileError.value = tm("workspaceFiles.downloadFailed");
+    if (props.projectId === projectId && selectedFilePath.value === path) {
+      fileError.value = tm("workspaceFiles.downloadFailed");
+    }
   } finally {
     fileDownloading.value = false;
   }
@@ -463,7 +749,7 @@ function formatSize(size: number) {
 
 <style scoped>
 .workspace-files-panel {
-  --chat-side-panel-width: clamp(340px, 29vw, 440px);
+  --chat-side-panel-width: 320px;
   width: var(--chat-side-panel-width);
   height: calc(100% - var(--chat-panel-top-offset, 0px));
   margin-top: var(--chat-panel-top-offset, 0px);
@@ -474,49 +760,196 @@ function formatSize(size: number) {
   flex-direction: column;
   flex: 0 0 auto;
   min-width: 0;
+  overflow: hidden;
 }
-
-.workspace-preview-header {
+.workspace-files-panel.has-preview {
+  --chat-side-panel-width: min(52vw, 820px);
+}
+.workspace-tabs-header {
   display: flex;
   align-items: center;
-  justify-content: space-between;
-  gap: 12px;
+  gap: 6px;
+  min-height: 48px;
+  padding: 0 10px 0 8px;
+  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.08);
 }
-
-.workspace-toolbar {
-  min-height: 52px;
-  padding: 8px 8px 8px 12px;
+.workspace-tabs {
   display: flex;
   align-items: center;
+  flex: 1;
+  min-width: 0;
   gap: 4px;
+  overflow-x: auto;
+  scrollbar-width: thin;
+  padding: 6px 0;
 }
-
-.workspace-files-actions {
+.workspace-tab {
+  display: flex;
+  align-items: center;
+  gap: 8px;
   min-width: 0;
+  padding: 8px 10px;
+  border: 0;
+  border-radius: 8px;
+  background: transparent;
+  color: rgba(var(--v-theme-on-surface), 0.55);
+  font: inherit;
+  font-size: 13px;
+  cursor: pointer;
+  text-align: left;
+}
+.workspace-tab svg {
+  flex-shrink: 0;
+}
+.workspace-tab span {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.workspace-files-tab {
+  flex: 0 0 auto;
+  position: sticky;
+  left: 0;
+  z-index: 1;
+  background: var(--chat-page-bg, rgb(var(--v-theme-surface)));
+}
+.workspace-file-tab {
+  display: flex;
+  align-items: center;
+  flex: 0 0 auto;
+  max-width: 200px;
+  border-radius: 8px;
+  padding-right: 5px;
+}
+.workspace-file-tab .workspace-tab {
+  flex: 1;
+  padding-right: 6px;
+}
+.workspace-file-tab.is-preview .workspace-tab span {
+  font-style: italic;
+}
+.workspace-file-tab.active,
+.workspace-files-tab[aria-selected="true"] {
+  background: rgba(var(--v-theme-on-surface), 0.07);
+}
+.workspace-tab[aria-selected="true"] {
+  color: rgb(var(--v-theme-on-surface));
+  font-weight: 600;
+}
+.workspace-file-tab:hover {
+  background: rgba(var(--v-theme-on-surface), 0.045);
+}
+.workspace-tab-close {
+  display: grid;
+  place-items: center;
+  flex: 0 0 22px;
+  width: 22px;
+  height: 22px;
+  padding: 0;
+  border: 0;
+  border-radius: 5px;
+  background: transparent;
+  color: rgba(var(--v-theme-on-surface), 0.4);
+  cursor: pointer;
+}
+.workspace-tab-close:hover {
+  background: rgba(var(--v-theme-on-surface), 0.1);
+  color: rgb(var(--v-theme-on-surface));
+}
+.workspace-tab:focus-visible,
+.workspace-tab-close:focus-visible,
+.workspace-tree-row:focus-visible {
+  outline: 2px solid rgb(var(--v-theme-primary));
+  outline-offset: -2px;
+}
+.workspace-path-bar {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  min-height: 43px;
+  padding: 4px 10px 4px 16px;
+  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.08);
+}
+.workspace-breadcrumbs {
+  display: flex;
+  align-items: center;
+  gap: 5px;
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  font-size: 12px;
+  white-space: nowrap;
+  color: rgba(var(--v-theme-on-surface), 0.45);
+}
+.workspace-breadcrumbs span {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  flex: 0 1 auto;
+  min-width: 24px;
+}
+.workspace-breadcrumbs svg {
+  flex-shrink: 0;
+}
+.workspace-breadcrumbs .is-filename {
+  color: rgb(var(--v-theme-on-surface));
+  flex-shrink: 0;
+  max-width: 65%;
+}
+.workspace-preview-actions {
   display: flex;
   align-items: center;
   flex: 0 0 auto;
   gap: 2px;
 }
-
-.workspace-filter {
-  height: 36px;
+.workspace-body {
+  display: flex;
+  position: relative;
+  min-height: 0;
+  flex: 1;
+  overflow: hidden;
+}
+.workspace-preview {
+  flex: 1;
   min-width: 0;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+}
+.workspace-tree-pane {
+  display: flex;
+  flex-direction: column;
   flex: 1;
-  padding: 0 10px;
-  border: 1px solid rgba(var(--v-theme-on-surface), 0.14);
-  border-radius: 9px;
+  min-height: 0;
+  min-width: 0;
+  background: var(--chat-page-bg, rgb(var(--v-theme-surface)));
+}
+.has-preview .workspace-tree-pane {
+  flex: 0 0 clamp(180px, 15vw, 220px);
+  border-left: 1px solid rgba(var(--v-theme-on-surface), 0.08);
+}
+.workspace-tree-toolbar {
   display: flex;
   align-items: center;
-  gap: 8px;
-  color: rgba(var(--v-theme-on-surface), 0.52);
+  gap: 4px;
+  padding: 10px 6px 8px 10px;
+}
+.workspace-filter {
+  display: flex;
+  align-items: center;
+  flex: 1;
+  min-width: 0;
+  gap: 7px;
+  height: 34px;
+  padding: 0 9px;
+  border: 1px solid rgba(var(--v-theme-on-surface), 0.1);
+  border-radius: 8px;
+  color: rgba(var(--v-theme-on-surface), 0.4);
 }
-
 .workspace-filter:focus-within {
-  border-color: rgba(var(--v-theme-on-surface), 0.32);
+  border-color: rgba(var(--v-theme-on-surface), 0.3);
 }
-
 .workspace-filter input {
+  width: 0;
   min-width: 0;
   flex: 1;
   border: 0;
@@ -524,51 +957,32 @@ function formatSize(size: number) {
   background: transparent;
   color: rgb(var(--v-theme-on-surface));
   font: inherit;
-  font-size: 13px;
+  font-size: 12px;
 }
-
 .workspace-filter input::-webkit-search-cancel-button {
   display: none;
 }
-
 .workspace-filter button {
-  width: 22px;
-  height: 22px;
-  padding: 0;
-  border: 0;
-  border-radius: 5px;
-  background: transparent;
-  color: inherit;
   display: grid;
   place-items: center;
+  width: 18px;
+  height: 18px;
+  border: 0;
+  border-radius: 4px;
+  color: inherit;
+  background: transparent;
   cursor: pointer;
 }
-
-.workspace-filter button:hover {
-  background: rgba(var(--v-theme-on-surface), 0.08);
-}
-
 .workspace-error {
-  margin: 0 12px 8px;
+  margin: 0 10px 8px;
   font-size: 12px;
 }
-
 .workspace-tree {
   min-height: 0;
-  flex: 1 1 auto;
+  flex: 1;
   overflow: auto;
-  padding: 2px 8px 10px;
-  display: flex;
-  flex-direction: column;
-  gap: 2px;
-}
-
-.workspace-tree--with-preview {
-  flex: 0 1 42%;
-  min-height: 140px;
-  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.1);
+  padding: 0 8px 12px;
 }
-
 .workspace-state,
 .workspace-preview-state {
   min-height: 110px;
@@ -579,150 +993,166 @@ function formatSize(size: number) {
   font-size: 13px;
   text-align: center;
 }
-
+.workspace-preview-state {
+  flex: 1;
+}
+.workspace-preview-empty {
+  display: flex;
+  flex: 1;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 14px;
+  padding: 24px;
+  text-align: center;
+  font-size: 13px;
+  color: rgba(var(--v-theme-on-surface), 0.35);
+}
 .workspace-tree-row {
+  display: flex;
+  align-items: center;
+  gap: 6px;
   width: 100%;
   height: 30px;
+  margin: 1px 0;
   padding-right: 8px;
   border: 0;
   border-radius: 6px;
   background: transparent;
   color: inherit;
-  display: flex;
-  align-items: center;
-  gap: 6px;
   cursor: pointer;
   text-align: left;
 }
-
 .workspace-tree-row:hover,
 .workspace-tree-row--active {
-  background: rgba(var(--v-theme-on-surface), 0.07);
+  background: rgba(var(--v-theme-on-surface), 0.065);
 }
-
 .workspace-tree-chevron {
-  width: 16px;
-  height: 18px;
-  flex: 0 0 16px;
   display: grid;
   place-items: center;
-  color: rgba(var(--v-theme-on-surface), 0.58);
+  flex: 0 0 14px;
+  color: rgba(var(--v-theme-on-surface), 0.4);
 }
-
 .workspace-folder-icon {
-  flex: 0 0 auto;
-  color: #d5a84a;
+  flex-shrink: 0;
+  color: #bc995e;
 }
-
 .workspace-file-icon {
-  flex: 0 0 auto;
-  color: rgba(var(--v-theme-on-surface), 0.58);
+  flex-shrink: 0;
+  color: rgba(var(--v-theme-on-surface), 0.45);
 }
-
 .workspace-tree-name {
-  min-width: 0;
   flex: 1;
+  min-width: 0;
   overflow: hidden;
-  font-size: 13px;
   text-overflow: ellipsis;
   white-space: nowrap;
+  font-size: 12px;
 }
-
 .workspace-tree-size {
-  flex: 0 0 auto;
-  color: rgba(var(--v-theme-on-surface), 0.42);
+  flex-shrink: 0;
   font-size: 10px;
+  color: rgba(var(--v-theme-on-surface), 0.3);
 }
-
-.workspace-preview {
-  min-height: 0;
-  flex: 1 1 58%;
+.workspace-code-view {
   display: flex;
-  flex-direction: column;
-}
-
-.workspace-preview-header {
-  min-height: 40px;
-  padding: 4px 8px 4px 14px;
-  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.08);
-}
-
-.workspace-preview-path {
-  min-width: 0;
-  overflow: hidden;
-  font-size: 12px;
-  font-weight: 600;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-}
-
-.workspace-preview-actions {
-  flex: 0 0 auto;
-  display: flex;
-  align-items: center;
-  gap: 2px;
-}
-
-.workspace-preview-state {
   flex: 1;
-}
-
-.workspace-preview-content {
   min-height: 0;
-  flex: 1;
-  margin: 0;
   overflow: auto;
-  padding: 12px 14px 20px;
-  background: rgba(var(--v-theme-on-surface), 0.025);
-  color: rgb(var(--v-theme-on-surface));
+}
+.workspace-preview-content,
+.workspace-line-numbers {
+  margin: 0;
+  padding: 16px 18px 24px 12px;
   font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
   font-size: 12px;
-  line-height: 1.55;
+  line-height: 1.75;
   tab-size: 2;
   white-space: pre;
 }
-
-.workspace-dialog-preview {
-  height: min(78vh, 760px);
+.workspace-preview-content {
+  min-width: 0;
+  flex: 1;
+}
+.workspace-line-numbers {
+  position: sticky;
+  left: 0;
+  padding-left: 16px;
+  padding-right: 10px;
+  color: rgba(var(--v-theme-on-surface), 0.28);
   background: var(--chat-page-bg, rgb(var(--v-theme-surface)));
-  color: rgb(var(--v-theme-on-surface));
+  text-align: right;
+  user-select: none;
+}
+.workspace-tree-scrim {
+  display: none;
+}
+.workspace-dialog-preview {
   display: flex;
   flex-direction: column;
+  height: min(86vh, 1000px);
+  background: var(--chat-page-bg, rgb(var(--v-theme-surface)));
+  color: rgb(var(--v-theme-on-surface));
 }
-
 .workspace-dialog-preview-header {
-  min-height: 56px;
-  padding: 6px 10px 6px 20px;
-  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.1);
   display: flex;
   align-items: center;
   justify-content: space-between;
   gap: 12px;
+  flex-shrink: 0;
+  border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.08);
 }
-
-.workspace-dialog-preview-content {
-  padding: 20px 24px 32px;
+.workspace-preview-path {
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-size: 14px;
+}
+@media (min-width: 761px) and (max-width: 1100px) {
+  .workspace-files-panel.has-preview {
+    position: absolute;
+    right: 0;
+    z-index: 20;
+    --chat-side-panel-width: min(72vw, 720px);
+    box-shadow: -12px 0 36px #0002;
+  }
 }
-
 @media (max-width: 760px) {
-  .workspace-files-panel {
+  .workspace-files-panel,
+  .workspace-files-panel.has-preview {
     position: fixed;
     inset: 0;
     z-index: 1300;
-    width: 100vw;
+    --chat-side-panel-width: 100vw;
     height: 100dvh;
     margin-top: 0;
     border-left: 0;
   }
-
-  .workspace-toolbar {
-    min-height: calc(52px + env(safe-area-inset-top));
-    padding: calc(8px + env(safe-area-inset-top)) 8px 8px 12px;
-    border-bottom: 1px solid rgba(var(--v-theme-on-surface), 0.1);
+  .workspace-tabs-header {
+    padding-top: env(safe-area-inset-top);
+    min-height: calc(48px + env(safe-area-inset-top));
   }
-
-  .workspace-tree--with-preview {
-    min-height: 160px;
+  .has-preview .workspace-tree-pane {
+    position: absolute;
+    inset: 0 0 0 auto;
+    z-index: 2;
+    width: min(280px, 85%);
+    box-shadow: -8px 0 24px #0002;
+  }
+  .workspace-tree-scrim {
+    display: block;
+    position: absolute;
+    inset: 0;
+    z-index: 1;
+    border: 0;
+    background: #0003;
+  }
+  .workspace-body {
+    padding-bottom: env(safe-area-inset-bottom);
+  }
+  .workspace-file-tab {
+    max-width: 160px;
   }
 }
 </style>
diff --git a/dashboard/src/components/chat/WorkspacePdfPage.vue b/dashboard/src/components/chat/WorkspacePdfPage.vue
new file mode 100644
index 0000000000..ec953eb4ad
--- /dev/null
+++ b/dashboard/src/components/chat/WorkspacePdfPage.vue
@@ -0,0 +1,137 @@
+<template>
+  <div
+    class="pdf-page"
+    :style="{ width: `${width}px`, height: `${height}px` }"
+    role="img"
+    :aria-label="tm('workspaceFiles.pdf.pageLabel', { page, total })"
+  >
+    <div v-if="error" class="pdf-placeholder pdf-error" role="alert">
+      {{ error }}
+    </div>
+    <div v-else-if="!rendered" class="pdf-placeholder" aria-hidden="true">
+      <v-progress-circular v-if="visible" indeterminate size="22" width="2" />
+      <span>{{ page }}</span>
+    </div>
+    <div ref="pageHost" class="pdf-canvas" />
+  </div>
+</template>
+
+<script setup lang="ts">
+import { onBeforeUnmount, onMounted, ref, watch } from "vue";
+import type { PDFDocumentProxy, RenderTask } from "pdfjs-dist";
+import { useModuleI18n } from "@/i18n/composables";
+
+const props = defineProps<{
+  document: PDFDocumentProxy;
+  page: number;
+  total: number;
+  width: number;
+  height: number;
+  scrollRoot: HTMLElement | null;
+}>();
+const { tm } = useModuleI18n("features/chat");
+const pageHost = ref<HTMLElement | null>(null);
+const visible = ref(false);
+const rendered = ref(false);
+const error = ref("");
+let observer: IntersectionObserver | undefined;
+onMounted(() => {
+  observer = new IntersectionObserver(
+    ([entry]) => {
+      visible.value = entry.isIntersecting;
+    },
+    {
+      root: props.scrollRoot,
+      rootMargin: "600px 0px",
+    },
+  );
+  if (pageHost.value) observer.observe(pageHost.value);
+});
+onBeforeUnmount(() => observer?.disconnect());
+
+watch(
+  [visible, () => props.document, () => props.width, () => props.page],
+  async ([nearViewport, document, width, pageNumber], _, onCleanup) => {
+    let cancelled = false;
+    let task: RenderTask | undefined;
+    let canvas: HTMLCanvasElement | undefined;
+    onCleanup(() => {
+      cancelled = true;
+      task?.cancel();
+      canvas?.remove();
+      // Release the raster buffer when a page leaves the nearby viewport.
+      if (canvas) canvas.width = canvas.height = 0;
+    });
+    rendered.value = false;
+    error.value = "";
+    if (!nearViewport || width <= 0) return;
+    try {
+      const page = await document.getPage(pageNumber);
+      if (cancelled) return;
+      const original = page.getViewport({ scale: 1 });
+      const view = page.getViewport({ scale: width / original.width });
+      const ratio = Math.min(
+        window.devicePixelRatio || 1,
+        2,
+        Math.sqrt(8_000_000 / (view.width * view.height)),
+        8192 / view.width,
+        8192 / view.height,
+      );
+      canvas = window.document.createElement("canvas");
+      canvas.width = Math.max(1, Math.floor(view.width * ratio));
+      canvas.height = Math.max(1, Math.floor(view.height * ratio));
+      canvas.style.width = `${view.width}px`;
+      canvas.style.height = `${view.height}px`;
+      canvas.setAttribute("aria-hidden", "true");
+      task = page.render({
+        canvas,
+        viewport: view,
+        transform: [ratio, 0, 0, ratio, 0, 0],
+      });
+      await task.promise;
+      if (cancelled) return;
+      pageHost.value?.replaceChildren(canvas);
+      rendered.value = true;
+    } catch (cause) {
+      if (
+        !cancelled &&
+        (cause as Error)?.name !== "RenderingCancelledException"
+      ) {
+        error.value = tm("workspaceFiles.pdf.loadFailed");
+      }
+    }
+  },
+  { flush: "post" },
+);
+</script>
+
+<style scoped>
+.pdf-page {
+  position: relative;
+  flex: 0 0 auto;
+  background: white;
+  box-shadow: 0 1px 6px #0002;
+}
+.pdf-canvas {
+  position: absolute;
+  inset: 0;
+}
+.pdf-canvas :deep(canvas) {
+  display: block;
+}
+.pdf-placeholder {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-direction: column;
+  gap: 12px;
+  color: #888;
+  font-size: 13px;
+}
+.pdf-error {
+  padding: 24px;
+  text-align: center;
+}
+</style>
diff --git a/dashboard/src/components/chat/WorkspacePdfPreview.vue b/dashboard/src/components/chat/WorkspacePdfPreview.vue
new file mode 100644
index 0000000000..2ab87a1e5b
--- /dev/null
+++ b/dashboard/src/components/chat/WorkspacePdfPreview.vue
@@ -0,0 +1,272 @@
+<template>
+  <div class="workspace-pdf">
+    <div
+      ref="viewport"
+      class="pdf-scroll"
+      :aria-busy="loading"
+      @scroll.passive="rememberPage"
+    >
+      <div v-if="error" class="pdf-state" role="alert">{{ error }}</div>
+      <div v-else-if="loading" class="pdf-state" role="status">
+        <v-progress-circular indeterminate size="24" width="2" />
+        <span>{{ tm("workspaceFiles.pdf.loading") }}</span>
+      </div>
+      <div v-else-if="pdf" class="pdf-pages">
+        <WorkspacePdfPage
+          v-for="(layout, index) in pageLayouts"
+          :key="index"
+          :document="pdf"
+          :page="index + 1"
+          :total="pdf.numPages"
+          :width="layout.width"
+          :height="layout.height"
+          :scroll-root="viewport"
+        />
+      </div>
+    </div>
+    <div
+      v-if="pdf && !loading && !error"
+      class="pdf-zoom-hub"
+      role="group"
+      :aria-label="tm('workspaceFiles.pdf.zoomControls')"
+    >
+      <v-btn
+        icon
+        size="x-small"
+        variant="text"
+        :disabled="zoom <= 0.5"
+        :aria-label="tm('workspaceFiles.pdf.zoomOut')"
+        :title="tm('workspaceFiles.pdf.zoomOut')"
+        @click="emit('update:zoom', Math.max(0.5, zoom - 0.25))"
+        ><Minus :size="16"
+      /></v-btn>
+      <v-btn
+        size="x-small"
+        variant="text"
+        class="pdf-zoom-value"
+        :title="tm('workspaceFiles.pdf.fitWidth')"
+        :aria-label="tm('workspaceFiles.pdf.fitWidth')"
+        @click="emit('update:zoom', 1)"
+        >{{ Math.round(zoom * 100) }}%</v-btn
+      >
+      <v-btn
+        icon
+        size="x-small"
+        variant="text"
+        :disabled="zoom >= 3"
+        :aria-label="tm('workspaceFiles.pdf.zoomIn')"
+        :title="tm('workspaceFiles.pdf.zoomIn')"
+        @click="emit('update:zoom', Math.min(3, zoom + 0.25))"
+        ><Plus :size="16"
+      /></v-btn>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import {
+  computed,
+  nextTick,
+  onBeforeUnmount,
+  onMounted,
+  ref,
+  shallowRef,
+  watch,
+} from "vue";
+import { Minus, Plus } from "@lucide/vue";
+import {
+  getDocument,
+  GlobalWorkerOptions,
+  version,
+  type PDFDocumentProxy,
+  type PDFDocumentLoadingTask,
+} from "pdfjs-dist";
+import workerUrl from "pdfjs-dist/build/pdf.worker.min.mjs?url";
+import { useModuleI18n } from "@/i18n/composables";
+import WorkspacePdfPage from "./WorkspacePdfPage.vue";
+
+const props = defineProps<{ file: Blob; page: number; zoom: number }>();
+const emit = defineEmits<{
+  "update:page": [page: number];
+  "update:zoom": [zoom: number];
+}>();
+const { tm } = useModuleI18n("features/chat");
+const pdf = shallowRef<PDFDocumentProxy | null>(null);
+const viewport = ref<HTMLElement | null>(null);
+const width = ref(0);
+const loading = ref(true);
+const error = ref("");
+const pageSizes = shallowRef<Array<{ width: number; height: number }>>([]);
+const pageLayouts = computed(() => {
+  const pageWidth = Math.max(1, width.value - 32) * props.zoom;
+  let top = 16;
+  return pageSizes.value.map((size) => {
+    const height = (pageWidth * size.height) / size.width;
+    const layout = { width: pageWidth, height, top };
+    top += height + 16;
+    return layout;
+  });
+});
+GlobalWorkerOptions.workerSrc = workerUrl;
+const resourceBase = `${import.meta.env.BASE_URL}pdfjs/${version}/`;
+const observer = new ResizeObserver(([entry]) => {
+  width.value = Math.floor(entry.contentRect.width);
+});
+onMounted(() => {
+  if (viewport.value) observer.observe(viewport.value);
+});
+onBeforeUnmount(() => observer.disconnect());
+
+watch(
+  () => props.file,
+  async (file, _, onCleanup) => {
+    let cancelled = false;
+    let task: PDFDocumentLoadingTask | undefined;
+    onCleanup(() => {
+      cancelled = true;
+      void task?.destroy().catch(() => {});
+    });
+    pdf.value = null;
+    pageSizes.value = [];
+    loading.value = true;
+    error.value = "";
+    try {
+      const data = await file.arrayBuffer();
+      if (cancelled) return;
+      task = getDocument({
+        data,
+        cMapUrl: `${resourceBase}cmaps/`,
+        cMapPacked: true,
+        standardFontDataUrl: `${resourceBase}standard_fonts/`,
+        wasmUrl: `${resourceBase}wasm/`,
+        iccUrl: `${resourceBase}iccs/`,
+      });
+      const document = await task.promise;
+      if (cancelled) return;
+      // Read dimensions without rasterizing pages, keeping mixed-size page slots stable.
+      const sizes: Array<{ width: number; height: number }> = [];
+      for (let start = 1; start <= document.numPages; start += 20) {
+        const batch = await Promise.all(
+          Array.from(
+            { length: Math.min(20, document.numPages - start + 1) },
+            async (_, index) => {
+              const page = await document.getPage(start + index);
+              const { width, height } = page.getViewport({ scale: 1 });
+              return { width, height };
+            },
+          ),
+        );
+        if (cancelled) return;
+        sizes.push(...batch);
+      }
+      pdf.value = document;
+      pageSizes.value = sizes;
+    } catch (cause) {
+      if (cancelled) return;
+      error.value = tm(
+        (cause as Error)?.name === "PasswordException"
+          ? "workspaceFiles.pdf.passwordProtected"
+          : "workspaceFiles.pdf.loadFailed",
+      );
+    } finally {
+      if (!cancelled) loading.value = false;
+    }
+  },
+  { immediate: true },
+);
+
+watch(pageLayouts, async (layouts, previous, onCleanup) => {
+  let cancelled = false;
+  onCleanup(() => {
+    cancelled = true;
+  });
+  const container = viewport.value;
+  if (!container || !layouts.length) return;
+  const scrollTop = container.scrollTop;
+  const oldIndex = previous.findIndex(
+    (layout) => layout.top + layout.height > scrollTop,
+  );
+  const index = Math.min(
+    layouts.length - 1,
+    oldIndex >= 0 ? oldIndex : Math.max(0, props.page - 1),
+  );
+  const offset =
+    oldIndex >= 0
+      ? (scrollTop - previous[index].top) / previous[index].height
+      : 0;
+  await nextTick();
+  if (cancelled) return;
+  // Keep the same position within the page when zooming or resizing the panel.
+  container.scrollTop = Math.max(
+    0,
+    layouts[index].top + offset * layouts[index].height,
+  );
+});
+
+function rememberPage() {
+  if (loading.value || !viewport.value) return;
+  const top = viewport.value.scrollTop + 16;
+  const index = pageLayouts.value.findIndex(
+    (layout) => layout.top + layout.height > top,
+  );
+  if (index >= 0 && index + 1 !== props.page) emit("update:page", index + 1);
+}
+</script>
+
+<style scoped>
+.workspace-pdf {
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+  min-height: 0;
+  min-width: 0;
+}
+.pdf-scroll {
+  overflow: auto;
+  overflow-anchor: none;
+  scrollbar-gutter: stable;
+  flex: 1;
+  min-height: 0;
+  background: rgba(var(--v-theme-on-surface), 0.04);
+}
+.pdf-pages {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 16px;
+  width: max-content;
+  min-width: 100%;
+  padding: 16px 16px 80px;
+}
+.pdf-zoom-hub {
+  position: absolute;
+  right: 20px;
+  bottom: 16px;
+  z-index: 1;
+  display: flex;
+  align-items: center;
+  gap: 2px;
+  padding: 5px 6px;
+  border: 1px solid rgba(var(--v-theme-on-surface), 0.12);
+  border-radius: 12px;
+  background: rgba(var(--v-theme-surface), 0.92);
+  color: rgb(var(--v-theme-on-surface));
+  box-shadow: 0 4px 20px #0002;
+  backdrop-filter: blur(12px);
+}
+.pdf-zoom-value {
+  min-width: 50px;
+  font-variant-numeric: tabular-nums;
+}
+.pdf-state {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 12px;
+  padding: 32px 16px;
+  text-align: center;
+  font-size: 13px;
+  color: rgba(var(--v-theme-on-surface), 0.65);
+}
+</style>
diff --git a/dashboard/src/i18n/locales/en-US/features/chat.json b/dashboard/src/i18n/locales/en-US/features/chat.json
index 5305103ea5..46fdde1a25 100644
--- a/dashboard/src/i18n/locales/en-US/features/chat.json
+++ b/dashboard/src/i18n/locales/en-US/features/chat.json
@@ -173,9 +173,9 @@
     "confirmDelete": "Are you sure you want to delete project \"{title}\"? Conversations in this project will not be deleted."
   },
   "workspaceFiles": {
-    "title": "Workspace Files",
-    "open": "Open workspace files",
-    "close": "Close workspace files",
+    "title": "Files",
+    "open": "Open files",
+    "close": "Close files",
     "refresh": "Refresh file tree",
     "filter": "Filter files...",
     "clearFilter": "Clear file filter",
@@ -188,7 +188,23 @@
     "downloadFailed": "Failed to download this file",
     "dialogPreview": "Open larger preview",
     "closePreview": "Close file preview",
-    "closeDialogPreview": "Close larger preview"
+    "closeDialogPreview": "Close larger preview",
+    "pdf": {
+      "zoomControls": "PDF zoom",
+      "zoomOut": "Zoom out",
+      "zoomIn": "Zoom in",
+      "fitWidth": "Fit page width",
+      "loading": "Loading PDF…",
+      "pageLabel": "Page {page} of {total}",
+      "passwordProtected": "This PDF is password protected. Download it to open it with a password.",
+      "loadFailed": "Unable to preview this PDF. You can still download the file.",
+      "tooLarge": "PDFs larger than 50 MB cannot be previewed. Download the file to view it."
+    },
+    "openTabs": "Open files",
+    "closeTab": "Close {name}",
+    "showTree": "Show file tree",
+    "hideTree": "Hide file tree",
+    "selectFile": "Select a file to preview"
   },
   "time": {
     "today": "Today",
diff --git a/dashboard/src/i18n/locales/ja-JP/features/chat.json b/dashboard/src/i18n/locales/ja-JP/features/chat.json
index 9953882406..a6b24444d9 100644
--- a/dashboard/src/i18n/locales/ja-JP/features/chat.json
+++ b/dashboard/src/i18n/locales/ja-JP/features/chat.json
@@ -173,9 +173,9 @@
     "confirmDelete": "プロジェクト「{title}」を削除しますか？プロジェクト内の会話は削除されません。"
   },
   "workspaceFiles": {
-    "title": "ワークスペースのファイル",
-    "open": "ワークスペースのファイルを開く",
-    "close": "ワークスペースのファイルを閉じる",
+    "title": "ファイル",
+    "open": "ファイルを開く",
+    "close": "ファイルパネルを閉じる",
     "refresh": "ファイルツリーを再読み込み",
     "filter": "ファイルを絞り込み…",
     "clearFilter": "ファイルの絞り込みを解除",
@@ -188,7 +188,23 @@
     "downloadFailed": "ファイルのダウンロードに失敗しました",
     "dialogPreview": "拡大プレビューを開く",
     "closePreview": "ファイルプレビューを閉じる",
-    "closeDialogPreview": "拡大プレビューを閉じる"
+    "closeDialogPreview": "拡大プレビューを閉じる",
+    "pdf": {
+      "zoomControls": "PDF のズーム",
+      "zoomOut": "縮小",
+      "zoomIn": "拡大",
+      "fitWidth": "ページ幅に合わせる",
+      "loading": "PDF を読み込み中…",
+      "pageLabel": "{total} ページ中 {page} ページ",
+      "passwordProtected": "この PDF はパスワードで保護されています。ダウンロードしてパスワードを入力してください。",
+      "loadFailed": "この PDF をプレビューできません。ファイルをダウンロードして確認してください。",
+      "tooLarge": "50 MB を超える PDF はプレビューできません。ダウンロードして確認してください。"
+    },
+    "openTabs": "開いているファイル",
+    "closeTab": "{name} を閉じる",
+    "showTree": "ファイルツリーを表示",
+    "hideTree": "ファイルツリーを隠す",
+    "selectFile": "ファイルを選択してプレビュー"
   },
   "time": {
     "today": "今日",
diff --git a/dashboard/src/i18n/locales/ru-RU/features/chat.json b/dashboard/src/i18n/locales/ru-RU/features/chat.json
index 5d2d53009e..0f0c3495af 100644
--- a/dashboard/src/i18n/locales/ru-RU/features/chat.json
+++ b/dashboard/src/i18n/locales/ru-RU/features/chat.json
@@ -173,9 +173,9 @@
     "confirmDelete": "Вы уверены, что хотите удалить проект «{title}»? Диалоги внутри проекта не будут удалены."
   },
   "workspaceFiles": {
-    "title": "Файлы рабочей области",
-    "open": "Открыть файлы рабочей области",
-    "close": "Закрыть файлы рабочей области",
+    "title": "Файлы",
+    "open": "Открыть файлы",
+    "close": "Закрыть панель файлов",
     "refresh": "Обновить дерево файлов",
     "filter": "Фильтр файлов...",
     "clearFilter": "Очистить фильтр файлов",
@@ -188,7 +188,23 @@
     "downloadFailed": "Не удалось скачать файл",
     "dialogPreview": "Открыть увеличенный просмотр",
     "closePreview": "Закрыть предпросмотр файла",
-    "closeDialogPreview": "Закрыть увеличенный просмотр"
+    "closeDialogPreview": "Закрыть увеличенный просмотр",
+    "pdf": {
+      "zoomControls": "Масштаб PDF",
+      "zoomOut": "Уменьшить",
+      "zoomIn": "Увеличить",
+      "fitWidth": "По ширине страницы",
+      "loading": "Загрузка PDF…",
+      "pageLabel": "Страница {page} из {total}",
+      "passwordProtected": "Этот PDF защищён паролем. Скачайте файл и откройте его с паролем.",
+      "loadFailed": "Не удалось открыть PDF для просмотра. Вы можете скачать файл.",
+      "tooLarge": "Предпросмотр PDF размером более 50 МБ недоступен. Скачайте файл для просмотра."
+    },
+    "openTabs": "Открытые файлы",
+    "closeTab": "Закрыть {name}",
+    "showTree": "Показать дерево файлов",
+    "hideTree": "Скрыть дерево файлов",
+    "selectFile": "Выберите файл для просмотра"
   },
   "time": {
     "today": "Сегодня",
diff --git a/dashboard/src/i18n/locales/zh-CN/features/chat.json b/dashboard/src/i18n/locales/zh-CN/features/chat.json
index 96810a7051..7569914647 100644
--- a/dashboard/src/i18n/locales/zh-CN/features/chat.json
+++ b/dashboard/src/i18n/locales/zh-CN/features/chat.json
@@ -173,9 +173,9 @@
     "confirmDelete": "确定要删除项目 \"{title}\" 吗？项目中的对话不会被删除。"
   },
   "workspaceFiles": {
-    "title": "工作区文件",
-    "open": "打开工作区文件",
-    "close": "关闭工作区文件",
+    "title": "文件",
+    "open": "打开文件",
+    "close": "关闭文件面板",
     "refresh": "刷新文件树",
     "filter": "筛选文件...",
     "clearFilter": "清除文件筛选",
@@ -188,7 +188,23 @@
     "downloadFailed": "下载文件失败",
     "dialogPreview": "放大预览",
     "closePreview": "关闭文件预览",
-    "closeDialogPreview": "关闭放大预览"
+    "closeDialogPreview": "关闭放大预览",
+    "pdf": {
+      "zoomControls": "PDF 缩放",
+      "zoomOut": "缩小",
+      "zoomIn": "放大",
+      "fitWidth": "适应页面宽度",
+      "loading": "正在加载 PDF…",
+      "pageLabel": "第 {page} 页，共 {total} 页",
+      "passwordProtected": "此 PDF 受密码保护，请下载后输入密码查看。",
+      "loadFailed": "无法预览此 PDF，仍可下载文件查看。",
+      "tooLarge": "超过 50 MB 的 PDF 暂不支持预览，请下载后查看。"
+    },
+    "openTabs": "已打开的文件",
+    "closeTab": "关闭 {name}",
+    "showTree": "展开文件树",
+    "hideTree": "收起文件树",
+    "selectFile": "选择文件开始预览"
   },
   "time": {
     "today": "今天",
diff --git a/dashboard/vite.config.ts b/dashboard/vite.config.ts
index fef80e4367..0c7e434b9a 100644
--- a/dashboard/vite.config.ts
+++ b/dashboard/vite.config.ts
@@ -6,6 +6,8 @@ import vuetify from 'vite-plugin-vuetify';
 import webfontDl from 'vite-plugin-webfont-dl';
 // @ts-ignore — .mjs not in TS project scope; Vite resolves this at runtime
 import { runMdiSubset } from './scripts/subset-mdi-font.mjs';
+// @ts-ignore — .mjs not in TS project scope; Vite resolves this at runtime
+import { pdfjsAssets } from './scripts/pdfjs-assets.mjs';
 
 const t2iShikiRuntimePath = fileURLToPath(
   new URL('../astrbot/core/utils/t2i/template/shiki_runtime.iife.js', import.meta.url)
@@ -61,6 +63,7 @@ export default defineConfig(({ command }) => ({
     // Only run MDI subsetting during production builds, skip in dev server
     ...(command === 'build' ? [mdiSubset()] : []),
     t2iShikiRuntimeAsset(),
+    pdfjsAssets(),
     vue({
       template: {
         compilerOptions: {