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.
npx agentmods add skills/launch52-ai/flutter-template/local-authnpx skills add launch52-ai/flutter-template --skill local-authgit clone --depth 1 https://github.com/launch52-ai/flutter-templateWhat 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 | $0.00046 | $0.01575 |
| Opus 5 | $0.00023 | $0.00788 |
| Sonnet 5 | $0.00009 | $0.00315 |
| Haiku 4.5 | $0.00005 | $0.00158 |
Grade A, and why
local-auth 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.
How it starts
The opening of the file, as written. The whole thing — 199 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Local Auth - Device Authentication
Local device authentication using biometrics (Face ID, Touch ID, fingerprint) and device credentials (PIN, pattern, password). Configurable security levels from basic to banking-grade.
When to Use This Skill
- Adding biometric/device unlock to an app
- Implementing app lock after background timeout
- Securing sensitive actions (payments, delete, view PII)
- User asks "biometric", "face id", "fingerprint", "app lock", "local auth"
When NOT to Use This Skill
- Remote authentication - Use
/auth,/social-login,/phone-auth - Session tokens - Handled by
/authand/data - Secure storage - Already in
/core(flutter_secure_storage)
Questions to Ask
Before generating code, ask these questions:
- Use case: App unlock after timeout OR sensitive action confirmation OR both?
- Security level: Trust device (simple) OR detect biometric changes (banking-grade)?
- Lock screen: Generate lock screen UI OR service only?
- Settings toggle: Generate enable/disable toggle widget?
- App PIN: Include app-level PIN for devices without lock screen?
- Timeout: How long in background before requiring re-auth? (0 = immediate)
- Failure behavior: Force full re-login OR let device handle lockout?
Quick Reference
Dependencies
dependencies:
local_auth: ^2.3.0
Security Levels
| Level | Biometric Change | Use Case |
|---|---|---|
| Simple | Trust any enrolled biometric | Social apps, low-risk |
| Banking | Detect changes, require re-login | Finance, health, PII |
Authentication Options
| Option | iOS | Android |
|---|---|---|
| Face ID / Face Unlock | Yes | Yes |
| Touch ID / Fingerprint | Yes | Yes |
| Passcode | Yes | Yes |
| PIN / Pattern | N/A | Yes |
Core Components
| Component | Purpose |
|---|---|
LocalAuthService |
Wraps local_auth, handles platform checks |
LocalAuthNotifier |
State management, timeout tracking |
LocalAuthSettings |
User preferences (enabled, timeout) |
LockScreen |
Optional full-screen auth prompt |
LocalAuthToggle |
Optional settings widget |
AppPinService |
Optional app-level PIN (no device lock) |
What ships with it
17 files 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.
- checklist.md 5.6 KB
- patterns-guide.md 13 KB
- reference/providers/local_auth_provider.dart 4.6 KB
- reference/providers/local_auth_settings.dart 2.9 KB
- reference/providers/local_auth_state.dart 1.3 KB
- reference/services/app_pin_service.dart 6.5 KB
- reference/services/local_auth_service.dart 5.5 KB
- reference/utils/app_lifecycle_observer.dart 3.1 KB
- reference/utils/biometric_state_tracker.dart 9.3 KB
- reference/widgets/local_auth_toggle.dart 4.9 KB
- reference/widgets/lock_screen.dart 5.7 KB
- scripts/check.dart 9.2 KB
- security-guide.md 7.3 KB
- setup-guide.md 4.6 KB
- templates/android_manifest_addition.xml 322 B
- templates/info_plist_addition.xml 229 B
- troubleshooting-guide.md 3.7 KB
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.
- 2d ago First seen · 199 lines · 46 tokens per session scan A 866d1a347259
local-auth is a skill published in the GitHub repository launch52-ai/flutter-template (2 stars, last pushed 6mo ago), licensed MIT. It adds 46 tokens to every session and 1,575 once invoked, about $0.0002 per session on Opus 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.
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