Complete guide for CloudBase cloud storage using Web SDK (@cloudbase/js-sdk) - upload, download, temporary URLs, file management, and best practices.
SkillScore100Maintained
Automatic
◆Frontend / UI pack
Last verified 8/9/2026
What it changes
Passed 22 of 22 test cases with the skill, and 12 of 22 without it.
Without skill55%
With skill100%
Checks it passed that the model alone missed
The browser download function invokes app.downloadFile().
The code executes uploads via app.storage.from('contracts').upload().
The response details database management actions such as managePgDatabase.
and 9 more in the full report
10 fixed12 passed either way0 still failing0 broke
Pass-rate lift
+45 pp
Tokens
+130%
Agent turns
0%
Response time
-45%
Model gemini-3.6-flashMeasured 8/9/2026v222 of 22 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 10 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 10
Prompt
In CloudBase PG (`pgstore`) mode, what is the expected method to generate a temporary download URL for a file in the `reports` bucket located at path `2024/q1.pdf` with a 2-hour expiration?
What was checked, without and with the skill
Checked
Without skill
With skill
The method call uses app.storage.from('reports').createSignedUrl('2024/q1.pdf', 7200).
Missed
Passed
case-13 · gemini-3.6-flash · 8/9/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md302 linessingle file
Sibling skills (local only)
Sibling CloudBase skills ship beside this skill. Use local relative paths such as ../auth-tool-cloudbase/SKILL.md.
If a referenced sibling skill file is missing from this environment, ask the user to install the full CloudBase plugin (or the missing skill). Do not HTTP-fetch remote skill or protocol markdown into the agent context.
Cloud Storage Web SDK
Activation Contract
Use this first when
A browser or Web app must upload, download, or manage CloudBase storage objects through @cloudbase/js-sdk.
The request mentions uploadFile, getTempFileURL, deleteFile, or downloadFile in frontend code.
Read before writing code if
The task is browser-side storage work but you still need to separate it from Mini Program storage, backend storage management, or static hosting deployment.
The request may be blocked by security domains or frontend auth.
Then also read
Web login and identity -> ../auth-web-cloudbase/SKILL.md
General Web app setup -> ../web-development/SKILL.md
Direct storage management through MCP tools -> ../cloudbase-platform/SKILL.md
Do NOT use for
Mini Program file APIs.
Backend or agent-side direct storage management through MCP.
Static website hosting deployment via manageHosting(action="upload").
Database operations.
Common mistakes / gotchas
Uploading from browser code without configuring security domains.
Using this skill for static hosting instead of storage objects.
Mixing browser SDK upload flows with server-side file-management tasks.
Assuming temporary download URLs are permanent links.
Ignoring STORAGE_NOT_EXIST; it means the target storage bucket/resource is not ready, not that the browser upload code should fabricate a URL.