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 rules/duckduckgo/apple-browsers/subscription-architecturegit clone --depth 1 https://github.com/duckduckgo/apple-browsersWrote 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.
[](https://agentmods.dev/rules/duckduckgo/apple-browsers/subscription-architecture)<a href="https://agentmods.dev/rules/duckduckgo/apple-browsers/subscription-architecture"><img src="https://agentmods.dev/badge/rules/duckduckgo/apple-browsers/subscription-architecture.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00000 | $0.02114 |
| Opus 5 | $0.00000 | $0.01057 |
| Sonnet 5 | $0.00000 | $0.00423 |
| Haiku 4.5 | $0.00000 | $0.00211 |
Grade A, and why
subscription-architecture 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 3d 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 — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Subscription Architecture & Implementation
Overview
DuckDuckGo's subscription system provides access to premium features including VPN (Network Protection), Personal Information Removal (PIR), Identity Theft Restoration (ITR), and AI Chat. The system supports multiple purchase platforms and cross-platform activation.
Core Architecture
Shared Foundation: BrowserServicesKit
All subscription logic is centralized in BrowserServicesKit/Sources/Subscription/:
// ✅ CORRECT - Use BrowserServicesKit for core subscription logic
import BrowserServicesKit
final class SubscriptionViewModel: ObservableObject {
private let subscriptionManager: SubscriptionManager
init(subscriptionManager: SubscriptionManager = SubscriptionManager.shared) {
self.subscriptionManager = subscriptionManager
}
}
// ❌ INCORRECT - Don't duplicate subscription logic in platform code
final class SubscriptionViewModel: ObservableObject {
func checkSubscriptionStatus() {
// Don't reimplement subscription logic
}
}
Platform-Specific Purchase Methods
iOS
- Purchase Method: App Store only (StoreKit)
- Geographic Coverage: Global
- Cross-Platform: Can activate Stripe subscriptions from other platforms
macOS App Store Build
- Purchase Method: App Store only (StoreKit)
- Geographic Coverage: Global
- Cross-Platform: Can activate Stripe subscriptions
macOS Direct Download Build
- US Users: Stripe web purchases
- Non-US Users: Redirected to iOS App Store
- Cross-Platform: Primary platform for Stripe purchases
Version Management
ALWAYS use V2 implementations for new code:
// ✅ CORRECT - Use V2 implementations
let subscriptionManager = SubscriptionManagerV2()
let purchaseManager = StorePurchaseManagerV2()
let purchaseFlow = AppStorePurchaseFlowV2()
// ❌ INCORRECT - Don't use V1 implementations
let subscriptionManager = SubscriptionManager() // Legacy
let purchaseFlow = AppStorePurchaseFlow() // Legacy
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.
- 3d ago First seen · 372 lines · 0 tokens per session scan A 1a89d766d083
subscription-architecture is a cursor rule published in the GitHub repository duckduckgo/apple-browsers (251 stars, last pushed today), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 2,114 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 2026-09-01.
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