feature-storage

A set of rules for loading and displaying files from Firebase Storage in a Flutter package, including download URLs, JSON, cached data, images, and SVGs.

In plain words
What is it for?
Use it when fetching or displaying Firebase Storage content, configuring cache expiry, invalidating cached files, or adding a different storage backend.
Why use it?
It helps developers reuse the package's existing fetching, caching, and cache-invalidation code instead of rebuilding it. It also makes clear that uploads, deletion, and other storage services are not included.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/sampaio-tech/flutter-core-modules/feature-storage
Clone the repo
git clone --depth 1 https://github.com/sampaio-tech/flutter-core-modules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 1,404 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01404
Opus 5 $0.00000 $0.00702
Sonnet 5 $0.00000 $0.00281
Haiku 4.5 $0.00000 $0.00140

Measured 2d ago against content hash 0f99350bb044, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

feature-storage 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 2d 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.

.cursor/rules/feature-storage.mdc · 159 lines

How it starts

The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Feature: Storage — Rules

What Is Already Implemented — Check Before Building

Capability Status
Firebase Storage download URL fetch GetDownloadUrlUsecase
Firebase Storage JSON fetch GetJsonUsecase
Transparent SharedPreferences caching SharedPreferencesCacheLocalDataSource
Cache invalidation by date cutoff invalidateCacheBefore: DateTime parameter
Cache invalidation by TTL duration invalidateCacheDuration: Duration parameter
Display raster image from Storage ImageNetworkFromStorageWidget
Display SVG from Storage SvgFromStorageWidget
Debug/prod cache key separation CacheKey.key appends _debug in debug mode
Firebase Storage file upload ❌ Not in package — implement directly via firebase_storage
Firebase Storage file deletion ❌ Not in package — implement directly
Alternative storage backends (S3, etc.) ❌ Add a new StorageRemoteDataSource implementation

Before fetching or displaying Firebase Storage content, check whether the above widgets and notifiers already cover the requirement.


Layer Structure

lib/src/features/storage/
├── domain/
│   ├── repositories/storage_repository.dart           # abstract class with built-in cache logic
│   ├── data_sources/storage_remote_data_source.dart
│   └── usecases/ (GetDownloadUrlUsecase, GetJsonUsecase)
├── data/
│   ├── repositories/firebase_storage_repository.dart
│   └── data_sources/firebase_storage_remote_data_source.dart
└── presentation/
    ├── notifiers/
    │   ├── get_download_url_state_notifier.dart        # family provider
    │   └── get_json_state_notifier.dart                # family provider
    └── widgets/
        ├── image_network_from_storage_widget.dart
        └── svg_from_storage_widget.dart

Displaying Images and SVGs

Raster image (PNG/JPEG)

ImageNetworkFromStorageWidget(
  path: 'images/user_avatar.png',       // Firebase Storage path
  width: 48,
  height: 48,
  fit: BoxFit.cover,
  invalidateCacheDuration: const Duration(days: 7),
  progressIndicatorWidget: const CupertinoActivityIndicator(),
  errorWidget: const Icon(CupertinoIcons.person_circle),
)

Read the full file on GitHub · 159 lines

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.

  1. 2d ago First seen · 159 lines · 0 tokens per session scan A 0f99350bb044

Subscribe to this mod's changes

feature-storage is a cursor rule published in the GitHub repository sampaio-tech/flutter-core-modules (2 stars, last pushed 10d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,404 tokens. 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.