A guide for uploading files through Fusebase, from temporary upload to stored file and displayable URL.

Use it when building file uploads, stored-file records, download links, or file descriptors for other apps.

Saving file contents directly in a database can create size, permission, and security problems. This defines how to store file references and metadata instead.

How fusebase-dev/fusebase-flow configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to fusebase-dev/fusebase-flow. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/fusebase-dev/fusebase-flow/main/.agents/skills/file-upload/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/fusebase-dev/fusebase-flow

Made for: Claude Code.

Or install fusebase-flow, the plugin that ships this one along with the rest of its 56 skills, 8 commands, 4 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/fusebase-dev/fusebase-flow/file-upload/github.svg)](https://agentmods.dev/skills/fusebase-dev/fusebase-flow/file-upload)

Your own site

<a href="https://agentmods.dev/skills/fusebase-dev/fusebase-flow/file-upload"><img src="https://agentmods.dev/badge/skills/fusebase-dev/fusebase-flow/file-upload/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/fusebase-dev/fusebase-flow/file-upload"><img src="https://agentmods.dev/badge/skills/fusebase-dev/fusebase-flow/file-upload.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 634 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00035	$0.00634
Opus 5.5	$0.00014	$0.00254
Sonnet 5.5	$0.00007	$0.00127
Haiku 4.5	$0.00003	$0.00063

Measured 2mo ago against content hash f62094faea2f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

file-upload scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

file-upload — 100% identical, 8 lines differ

.agents/skills/file-upload/SKILL.md · 38 lines

How it starts

The opening of the file, as written. The whole thing — 38 lines — stays where its author put it; the contents beside it link to each section on GitHub.

File Upload

This skill is the single source of truth for the low-level file upload lifecycle. Load Upload Lifecycle for the canonical tempStoredFileName -> storedFileUUID -> readUrl / relative url -> file descriptor flow.

Hard rules

Never store user file/binary bytes in a FuseBase PostgreSQL isolated store (base64 / bytea / data URL), including “MVP” shortcuts. Upload with this skill / Gate files ops; persist only storedFileUUID, readUrl, and small metadata in SQL or dashboard cells.
Needing files.write is not a reason to put attachments in SQL. Sync Gate permissions (fusebase app update <appId> --sync-gate-permissions) instead.
Visitor / anonymous / public-link apps: browser visitor tokens usually cannot call files.write. Broker upload on the app feature backend with FBS_FEATURE_TOKEN, then return storedFileUUID / readUrl to the client.
Ordinary isolated-SQL write/execute paths are not the 64MiB importIsolatedStoreSqlRows cap — practical bodies are ~100–150 KB. Do not design attachments against SQL payload size.

When NOT To Use This Skill

Do not use this skill to describe how to write dashboard cell data. For dashboard files columns, load fusebase-dashboards and pass the already-uploaded file descriptor to batchPutDashboardData.
Do not use this skill for Gate MCP operation auth, scopes, or operation discovery. For Gate startMultipartFileUpload, completeMultipartFileUpload, and deleteFile, load fusebase-gate (prompt/reference files).
Do not copy upload endpoint or payload blocks into neighboring skills. Link to Upload Lifecycle and keep only a short handoff.

Scope

Owns: temp file creation, stored file creation, display URL rules, and file descriptor terminology.
Neighbor skills: fusebase-dashboards owns dashboard files cell writes; fusebase-gate owns Gate operation names, auth, and scope.
Required terminology: tempStoredFileName, storedFileUUID, readUrl, relative url, file descriptor.

Read the full file on GitHub · 38 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

references/upload-lifecycle.md 10 KB

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 38 lines · 35 tokens per session scan A f62094faea2f

Subscribe to this mod's changes

file-upload is a skill published in the GitHub repository fusebase-dev/fusebase-flow (9 stars, last pushed 13d ago), licensed MIT. It adds 35 tokens to every session and 634 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Backend and APIs Claude Code ai-coding-assistant codex cursor fusebase github-copilot

file-upload next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
file-uploadfusebase-dev/fusebase-flow	Skill	9	13d ago	MIT	A	35	Claude Code
adobe-express-cors-and-backendSandgrouse/adobe-express-dev-skill	Skill	9	2mo ago	none	A	92	Claude Code, Codex
adobe-express-oauth-authenticationSandgrouse/adobe-express-dev-skill	Skill	9	2mo ago	none	A	50	Claude Code, Codex
lov-optimize-tauri-backendlovstudio/skills	Skill	72	yesterday	MIT	A	71	Claude Code
lov-cli-creatorlovstudio/skills	Skill	72	yesterday	MIT	A	58	Claude Code
lov-api-creatorlovstudio/skills	Skill	72	yesterday	MIT	A	75	Claude Code
lov-cli2anythinglovstudio/skills	Skill	72	yesterday	MIT	A	55	Claude Code

fusebase-flow: Skill for Claude Code