debugging-network-issues

debugging-network-issues is a skill for Claude Code, Codex from daymade/claude-code-skills. It costs 194 tokens per session (11,484 once invoked), scanned A, original, MIT.

A method for investigating network, streaming, and protocol failures through layered experiments that try to disprove likely causes.

In plain words
What is it for?
It is for diagnosing connection resets, HTTP/2 stream errors, stalled SSE or long-polling requests, timeout patterns, certificate errors, and routing problems.
Why use it?
It helps avoid blaming the first plausible log message and narrows failures across clients, proxies, tunnels, CDNs, and servers.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit It is for diagnosing connection resets, HTTP/2 stream errors, stalled SSE or long-polling requests, timeout patterns, certificate errors, and routing problems.

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Install with agentmods
npx agentmods add skills/daymade/claude-code-skills/debugging-network-issues
About the project

Claude Code Skills Marketplace is a collection and marketplace of skills, plugins, agents, and instructions that extend Claude Code with specialized development workflows. It is for developers who want to install existing workflows or create, validate, and package their own Claude Code skills.

daymade/claude-code-skills · 1,381 stars · on GitHub

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.

Any agent
npx skills add daymade/claude-code-skills --skill debugging-network-issues
Clone the repo
git clone --depth 1 https://github.com/daymade/claude-code-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin debugging-network-issues/plugin install debugging-network-issues after adding the marketplace above.

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.

agentmods badge for debugging-network-issues

README.md
[![agentmods](https://agentmods.dev/badge/skills/daymade/claude-code-skills/debugging-network-issues.svg)](https://agentmods.dev/skills/daymade/claude-code-skills/debugging-network-issues)
Your own site
<a href="https://agentmods.dev/skills/daymade/claude-code-skills/debugging-network-issues"><img src="https://agentmods.dev/badge/skills/daymade/claude-code-skills/debugging-network-issues.svg" alt="Measured on agentmods" height="20"></a>
Per session 194 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 11,484 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 27 Apr 2026
  • Snyk warn 27 Apr 2026
How audits are shown
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 5.1 $0.00194 $0.11484
Opus 5 $0.00097 $0.05742
Sonnet 5 $0.00039 $0.02297
Haiku 4.5 $0.00019 $0.01148

Measured 3d ago against content hash d6e7a421fe48, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

debugging-network-issues scanned grade A with 1 finding 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.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/layered-isolation-probe.sh, scripts/mock-idle-upstream.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

| macOS Tailscale ⨯ proxy/VPN conflict (Shadowrocket / Clash / Surge): `tailscale ping` works but SSH/curl/git fails, `Connection closed by 198.18.x.x`, TUN DNS hijack, ~60s `getaddrinfo` resolver stall | **tunnel-doctor
debugging-network-issues/SKILL.md · 487 lines

How it starts

The opening of the file, as written. The whole thing — 487 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging Network Issues

Evidence-driven investigation methodology for incidents where the obvious cause is probably wrong. Built from a real 5-hour production case (see references/case-sse-rst-130s.md) where assumption-stacking wasted hours that a 10-minute layered experiment would have resolved.

Apply this skill when the user reports a network/streaming/protocol symptom and the investigator feels tempted to diagnose from one log line or one circumstantial data point. The skill's job is to slow that reflex down.

Triage first — is this a known domain?

Before applying the general methodology below, check whether the symptom points at a stack that already has a dedicated skill in this repo. Those carry the domain-specific symptom→cause→fix tables this skill deliberately stays general about — start there, and come back here for methodology if the root cause turns out to be elsewhere.

If the symptom is… Start with
macOS Tailscale ⨯ proxy/VPN conflict (Shadowrocket / Clash / Surge): tailscale ping works but SSH/curl/git fails, Connection closed by 198.18.x.x, TUN DNS hijack, ~60s getaddrinfo resolver stall tunnel-doctor
Cloudflare config: ERR_TOO_MANY_REDIRECTS, SSL-mode mismatch, DNS / proxy-status issues behind the orange cloud cloudflare-troubleshooting
Windows App / AVD / W365 RDP connection quality: WebSocket instead of UDP Shortpath, high RTT, STUN/TURN interference windows-remote-desktop-connection-doctor
Client-side proxy / VPN / TUN misrouting: one specific site fails with ERR_CONNECTION_CLOSED or SSL_ERROR_SYSCALL, other sites work, DNS returns fake/TUN IPs, and adding a PROXY rule did not help this skill — read references/case-proxy-tun-cname-override.md first
TLS certificate-verification errors (UNKNOWN_CERTIFICATE_VERIFICATION_ERROR, a cert for the wrong site) or mid-handshake EOFs on every DIRECT-routed/domestic domain at once, while proxied domains work — and any proxy health watchdog still reports green tunnel-doctor (TUN DIRECT split-brain step)
The proxy is reachable and the OS/Tailscale route is healthy, but bulk transfers are slow and changing the active exit/node changes the measured rate tunnel-doctor — proxy node / exit / chain capacity branch
Nothing errors — it is just slow. Every request returns 200, latency and health checks look fine, but transfers crawl, bulk jobs overrun their estimates, or files arrive truncated this skill — go straight to Step 0.7; the error-driven steps have nothing to bite on

Read the full file on GitHub · 487 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. 3d ago First seen · 487 lines · 194 tokens per session scan A d6e7a421fe48

Subscribe to this mod's changes

debugging-network-issues is a skill published in the GitHub repository daymade/claude-code-skills (1,381 stars, last pushed today), licensed MIT. It adds 194 tokens to every session and 11,484 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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