Improve: Enforce 15MB max file size limit before downloading/viewing sandbox inspect files (#200)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Adds a 15MB max preview limit with pre-read size checks, introduces
explicit unreadable states (file_type, too_large), and updates viewer
messaging accordingly.
> 
> - **Sandbox Inspect**:
> - **Preview size limit**: Introduces `MAX_VIEWABLE_FILE_SIZE_BYTES`
(15MB) and pre-checks file size via `files.getInfo` before reading.
Oversized files set `unreadable` with `reason: 'too_large'` and include
`size`.
> - **File content states**: Refactors to explicit types:
`TextFileContentState`, `ImageFileContentState`,
`UnreadableFileTypeContentState`, `UnreadableTooLargeContentState`.
> - **Error mapping**: On read errors and non-text/image blobs, sets
`unreadable` with `reason: 'file_type'`.
> - **Viewer UI**:
> - Renders size-specific message for oversized files and generic
message for unreadable type; wires new state variants.
> - **Utils**:
> - `determineFileContentState` now returns `unreadable` with `reason:
'file_type'` on decode failures.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
254300b. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Jakub Novák <[email protected]>

Author: ben-fornefeld

src/features/dashboard/sandbox/inspect/filesystem/store.ts

@@ -13,28 +13,38 @@ import { FilesystemNode } from './types'
 
 enableMapSet()
 
+export const MAX_VIEWABLE_FILE_SIZE_BYTES = 15 * 1024 * 1024 // 15MB
+
 interface FilesystemStatics {
   rootPath: string
 }
 
-interface ContentFileContentState {
-  text: string
+export interface TextFileContentState {
   type: 'text'
+  text: string
+}
+
+export interface ImageFileContentState {
+  type: 'image'
+  dataUri: string
 }
 
-interface UnreadableFileContentState {
+export interface UnreadableFileTypeContentState {
   type: 'unreadable'
+  reason: 'file_type'
 }
 
-interface ImageFileContentState {
-  dataUri: string
-  type: 'image'
+export interface UnreadableTooLargeContentState {
+  type: 'unreadable'
+  reason: 'too_large'
+  size: number
 }
 
 export type FileContentState =
-  | ContentFileContentState
-  | UnreadableFileContentState
+  | TextFileContentState
   | ImageFileContentState
+  | UnreadableFileTypeContentState
+  | UnreadableTooLargeContentState
 
 export type FileContentStateType = FileContentState['type']
 

src/features/dashboard/sandbox/inspect/sandbox-manager.ts

@@ -5,13 +5,16 @@ import {
   normalizePath,
 } from '@/lib/utils/filesystem'
 import {
+  FilesystemEventType,
   type EntryInfo,
   type FilesystemEvent,
-  FilesystemEventType,
   type Sandbox,
   type WatchHandle,
 } from 'e2b'
-import type { FilesystemStore } from './filesystem/store'
+import {
+  MAX_VIEWABLE_FILE_SIZE_BYTES,
+  type FilesystemStore,
+} from './filesystem/store'
 import { FilesystemNode } from './filesystem/types'
 
 export const HANDLED_ERRORS = {
@@ -322,6 +325,20 @@ export class SandboxManager {
     try {
       state.setLoading(normalizedPath, true)
 
+      const fileInfo = await this.sandbox.files.getInfo(normalizedPath, {
+        user: 'root',
+        requestTimeoutMs: 10_000,
+      })
+
+      if (fileInfo.size > MAX_VIEWABLE_FILE_SIZE_BYTES) {
+        state.setFileContent(normalizedPath, {
+          type: 'unreadable',
+          reason: 'too_large',
+          size: fileInfo.size,
+        })
+        return
+      }
+
       const blob = await this.sandbox.files.read(normalizedPath, {
         format: 'blob',
         requestTimeoutMs: 30_000,
@@ -337,7 +354,10 @@ export class SandboxManager {
       console.error(`Failed to read file ${normalizedPath}:`, err)
 
       state.setError(normalizedPath, errorMessage)
-      state.setFileContent(normalizedPath, { type: 'unreadable' })
+      state.setFileContent(normalizedPath, {
+        type: 'unreadable',
+        reason: 'file_type',
+      })
     } finally {
       state.setLoading(normalizedPath, false)
       state.setLoaded(normalizedPath, true)

src/features/dashboard/sandbox/inspect/viewer.tsx

@@ -10,6 +10,12 @@ import { AnimatePresence } from 'framer-motion'
 import { Download } from 'lucide-react'
 import { useEffect, useState } from 'react'
 import ShikiHighlighter, { Language } from 'react-shiki'
+
+import {
+  MAX_VIEWABLE_FILE_SIZE_BYTES,
+  type UnreadableFileTypeContentState,
+  type UnreadableTooLargeContentState,
+} from './filesystem/store'
 import SandboxInspectFrame from './frame'
 import { useContent } from './hooks/use-content'
 import { useFile } from './hooks/use-file'
@@ -117,7 +123,7 @@ function SandboxInspectViewerContent({
       ) : state.type === 'image' ? (
         <ImageContent name={name} dataUri={state.dataUri} />
       ) : (
-        <UnreadableContent onDownload={download} />
+        <UnreadableContent state={state} onDownload={download} />
       )}
     </SandboxInspectFrame>
   )
@@ -148,7 +154,7 @@ function TextContent({
   if (content.length === 0) {
     return (
       <div className="flex h-full flex-col items-center justify-center gap-3">
-        <span className="text-fg-secondary ">This file is empty.</span>
+        <span className="text-fg-secondary">This file is empty.</span>
         <Button variant="warning" size="sm" onClick={onDownload}>
           Download
           <Download className="ml-1.5 h-4 w-4" />
@@ -195,14 +201,32 @@ function ImageContent({ name, dataUri }: ImageContentProps) {
   )
 }
 
-interface UnreadableContent {
+interface UnreadableContentProps {
+  state: UnreadableFileTypeContentState | UnreadableTooLargeContentState
   onDownload: () => void
 }
 
-function UnreadableContent({ onDownload }: UnreadableContent) {
+function UnreadableContent({ state, onDownload }: UnreadableContentProps) {
+  const maxSizeMB = (MAX_VIEWABLE_FILE_SIZE_BYTES / 1024 / 1024).toFixed(0)
+
+  if (state.reason === 'too_large') {
+    const sizeMB = (state.size / 1024 / 1024).toFixed(1)
+    return (
+      <div className="flex h-full flex-col items-center justify-center gap-3">
+        <span className="text-fg-secondary">
+          File is too large to preview ({sizeMB} MB). Limit is {maxSizeMB} MB.
+        </span>
+        <Button variant="warning" size="sm" onClick={onDownload}>
+          Download
+          <Download className="ml-1.5 h-4 w-4" />
+        </Button>
+      </div>
+    )
+  }
+
   return (
     <div className="flex h-full flex-col items-center justify-center gap-3">
-      <span className="text-fg-secondary ">This file is not readable.</span>
+      <span className="text-fg-secondary">This file is not readable.</span>
       <Button variant="warning" size="sm" onClick={onDownload}>
         Download
         <Download className="ml-1.5 h-4 w-4" />

src/lib/utils/filesystem.ts

@@ -86,6 +86,6 @@ export async function determineFileContentState(
     const content = new TextDecoder('utf-8', { fatal: true }).decode(data)
     return { type: 'text', text: content }
   } catch {
-    return { type: 'unreadable' }
+    return { type: 'unreadable', reason: 'file_type' }
   }
 }