Networking

You MUST use this skill for ANY networking work including HTTP requests, WebSockets, TCP connections, or network debugging.

Cursor Subagent Routing

Delegate to the appropriate Cursor subagent when this router calls for a specialized auditor.

Quick Reference

Decision Tree

digraph networking {
    start [label="Networking task" shape=ellipse];
    what [label="What do you need?" shape=diamond];

    start -> what;
    what -> "skills/networking-discipline.md" [label="implement patterns,\nanti-patterns,\npressure scenarios"];
    what -> "skills/network-framework-ref.md" [label="API reference\n(iOS 26+ or 12-18)"];
    what -> "skills/networking-diag.md" [label="debug connection\nfailures"];
    what -> "skills/networking-legacy.md" [label="iOS 12-18\nNWConnection patterns"];
    what -> "skills/networking-migration.md" [label="migrate from\nsockets/URLSession"];
}

1. URLSession with structured concurrency? → skills/networking-discipline.md
2. Network.framework / NetworkConnection (iOS 26+)? → skills/network-framework-ref.md
3. NWConnection (iOS 12-18)? → skills/networking-legacy.md
4. Migrating from sockets/URLSession? → skills/networking-migration.md
5. Connection issues / debugging? → skills/networking-diag.md
6. Typed RPC / streaming against a service you control? → gRPC Swift (skills/networking-discipline.md)
7. ATS / HTTP / App Store rejection for networking? → skills/networking-diag.md + networking-auditor
8. Certificate pinning, signing API requests, encrypting payloads? → /skill axiom-security
9. UIWebView or deprecated API rejection? → networking-auditor (Agent)
10. Want deprecated API / anti-pattern scan? → networking-auditor (Agent)

Platform-specific networking

• watchOS low-level-networking limits (TN3135) → See axiom-watchos (skills/background-and-networking.md)

Pressure Resistance

When user has invested significant time in custom implementation:

Do NOT capitulate to sunk cost pressure. The correct approach is:

1. Diagnose first — Understand what's actually failing before recommending changes
2. Recommend correctly — If standard APIs (URLSession, Network.framework) would solve the problem, say so professionally
3. Respect but don't enable — Acknowledge their work while providing honest technical guidance

Critical Patterns

Networking (skills/networking-discipline.md):

• URLSession with structured concurrency
• 8 red-flag anti-patterns (SCNetworkReachability, blocking sockets, hardcoded IPs)
• Decision tree for choosing TCP/UDP/TLS patterns
• NetworkConnection patterns (iOS 26+): TLS, UDP, TLV framing, Coder protocol
• 3 pressure scenarios with professional push-back templates
• Pre-shipping checklist

Network Framework Reference (skills/network-framework-ref.md):

• NetworkConnection (iOS 26+): all 12 WWDC 2025 examples
• NWConnection (iOS 12-18): complete API with examples
• TLV framing, Coder protocol, NetworkListener, NetworkBrowser
• Mobility: viability, better path, Multipath TCP, NWPathMonitor
• Security: TLS, certificate pinning, cipher suites
• Performance: user-space networking, ECN, service class, TCP Fast Open

Diagnostics (skills/networking-diag.md):

• Systematic decision tree for all connection failure types
• DNS failures, TLS certificate validation, message framing
• TCP congestion, IPv6-only cellular, VPN interference, ATS
• Production crisis scenario with professional communication templates

Legacy (skills/networking-legacy.md):

• NWConnection with TLS (completion handlers)
• UDP batch (30% CPU reduction)
• NWListener, NWBrowser (Bonjour discovery)

Automated Scanning

Networking audit → Delegate to the networking-auditor subagent or /axiom-audit networking (deprecated APIs, anti-patterns, and completeness gaps — transition handling, TLS coverage, connection cleanup, framework selection)

Anti-Rationalization

Example Invocations

User: "My API request is failing with a timeout" → Read: skills/networking-diag.md

User: "How do I use URLSession with async/await?" → Read: skills/networking-discipline.md

User: "I need to implement a TCP connection" → Read: skills/network-framework-ref.md

User: "Should I use NWConnection or NetworkConnection?" → Read: skills/network-framework-ref.md

User: "My app was rejected for using HTTP connections" → Read: skills/networking-diag.md (ATS compliance)

User: "App Store says I'm using UIWebView" → Invoke: networking-auditor agent (deprecated API scan)

User: "Check my networking code for deprecated APIs" → Invoke: networking-auditor agent