China Mirror Resolver

China Mirror Resolver

Mirror URLs break frequently. This skill teaches the agent a self-healing workflow: discover → validate → configure the best available source. A baseline table provides offline fallback; web search enables self-repair.

Execution Flow

User error / request
      │
      ▼
 1. Identify tool type (Section 1)
      │
      ▼
 2. Detect current source config
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 3. Try ALL baseline sources for that tool (Section 2)
    Validate each with Section 4 thresholds (< 3s = good, 3–10s = acceptable)
      ├─ At least one source < 10s → pick fastest → go to step 6
      └─ All sources > 10s or failed ↓
      ▼
 4. [IF search capable] Search for latest sources (Section 3)
      ├─ Found candidates → go to step 5
      └─ No candidates found → report to user with baseline table as reference
    [IF no search] Report baseline failure to user, suggest manual URL
      │
      ▼
 5. Validate ALL candidates (Section 4), pick fastest passing one
      ├─ At least one passes → go to step 6
      └─ All fail → report failure to user, suggest checking network/proxy
      │
      ▼
 6. Backup original config → write new config → verify with test command
      │
      ▼
 7. Confirm result to user (show old source → new source, response time)

Graceful degradation: If the agent has no web search capability, skip step 4 and use only the baseline table. The skill remains functional with reduced self-healing ability.

Speed selection: When multiple sources pass validation, always select the one with the lowest response time. Test all candidates, not just the first.

1. Diagnostic Table

Match error keywords to identify the tool, then check current config:

2. Baseline Sources

High-stability institutional mirrors. Try these first. If all fail or are too slow (> 10s), proceed to Section 3 (search). Agents without search capability stop here.

pip

npm / yarn / pnpm

conda

Docker

Go

Rust

Maven / Gradle

Homebrew (macOS / Linuxbrew)

apt (Debian / Ubuntu)

yum / dnf (CentOS / RHEL / Fedora)

GitHub Accelerator

Hugging Face

3. Search Strategy

Capability gate: This section requires web search. If the agent lacks search capability, skip to Section 5 using only baseline sources.

3.1 Search Query Templates

Replace <YEAR> with current year. Use the agent's available search mechanism. Provide both Chinese and English queries for better coverage:

3.2 Source Credibility

Prioritize results in this order:

1. Official mirror site docs (mirrors.tuna.tsinghua.edu.cn/help, developer.aliyun.com/mirror)
2. Mirror provider's own site/README (goproxy.cn, npmmirror.com)
3. Recent posts (< 3 months) from reputable tech communities
4. GitHub repos with > 100 stars that aggregate mirror lists

Reject: undated articles, posts > 6 months old, zero-reply forum threads, unverifiable personal blogs.

3.3 Candidate Extraction Rules

Extracted URLs must:

• Use HTTPS protocol
• Belong to known institutions (.edu.cn, major cloud vendors, well-known OSS orgs) OR be cross-referenced in 2+ independent articles
• Come from articles published within the last 6 months

Security warning: Never use mirror sources from unknown individuals or unverifiable personal servers. Malicious mirrors can inject tampered packages. Especially for Docker and pip, only use sources from recognized institutions.

4. Validation

Every candidate must pass validation before being written to config.

4.1 Universal HTTP Check

# Linux / macOS
start=$(date +%s%N 2>/dev/null || perl -MTime::HiRes=time -e 'printf "%d\n",time()*1e9')
code=$(curl -o /dev/null -s -w "%{http_code}" --max-time 10 "<URL>")
end=$(date +%s%N 2>/dev/null || perl -MTime::HiRes=time -e 'printf "%d\n",time()*1e9')
echo "HTTP $code | $(( (end - start) / 1000000 ))ms"

# Windows PowerShell
$sw = [System.Diagnostics.Stopwatch]::StartNew()
try { $r = Invoke-WebRequest -Uri "<URL>" -TimeoutSec 10 -UseBasicParsing -ErrorAction Stop
  $sw.Stop(); "OK: HTTP $($r.StatusCode) | $($sw.ElapsedMilliseconds)ms"
} catch { $sw.Stop(); "FAIL: $_" }

4.2 Tool-Specific Validation

4.3 Acceptance Criteria

Selection rule: Test ALL available candidates (baseline + search-discovered), then select the one with the lowest response time that passes validation.

4.4 Batch Validation Scripts

Pre-built scripts in scripts/:

• scripts/validate.sh — Linux / macOS (bash). Supports --json flag for machine-readable output.
• scripts/validate.ps1 — Windows (PowerShell)

bash scripts/validate.sh              # test all, colored output
bash scripts/validate.sh pip           # test pip only
bash scripts/validate.sh all --json    # machine-readable JSON output

4.5 Security Notes on Validation

trusted-host warning: Using --trusted-host with pip disables SSL certificate verification for that host. This is a security trade-off. Only use it when the mirror is a known institution (e.g., .edu.cn, major cloud vendor) and the connection is within a trusted network. Prefer mirrors that have valid SSL certificates and do not require trusted-host.

5. Configuration

Core Principles

1. Backup first — Always backup the original config file before modifying
2. Merge, don't overwrite — For JSON configs (Docker daemon.json), read existing content and merge new fields. Never blindly overwrite the entire file
3. Permanent config — Write to config files, not just CLI flags
4. Verify after write — Run a test command to confirm the new source works

Detailed configuration templates for each tool are in references/config-templates.md. Below is a quick reference of the key commands.

Quick Reference

pip: pip config set global.index-url <URL>

npm: npm config set registry <URL>

yarn v1: yarn config set registry <URL>

yarn v2+: yarn config set npmRegistryServer <URL>

pnpm: pnpm config set registry <URL>

conda: conda config --add channels <URL> && conda config --set show_channel_urls yes

Docker: Read existing daemon.json, add/update registry-mirrors array, write back, restart Docker. See references/config-templates.md for merge logic.

Go: go env -w GOPROXY=<URL>,direct && go env -w GOSUMDB=sum.golang.google.cn

Rust (cargo): Write [source.crates-io] + [source.mirror] to ~/.cargo/config.toml

Rust (rustup): Set RUSTUP_DIST_SERVER and RUSTUP_UPDATE_ROOT env vars

Maven: Add <mirror> block to ~/.m2/settings.xml

Gradle (Groovy): Add maven { url '<URL>' } to repositories block

Gradle (Kotlin): Add maven(url = "<URL>") to repositories block

Homebrew: Set HOMEBREW_BREW_GIT_REMOTE, HOMEBREW_CORE_GIT_REMOTE, HOMEBREW_BOTTLE_DOMAIN env vars

apt: Replace archive.ubuntu.com with mirror host in /etc/apt/sources.list, then sudo apt update

yum/dnf: Backup /etc/yum.repos.d/, replace baseurl in repo files, then sudo yum makecache

GitHub: Prepend accelerator prefix: git clone <PREFIX>https://github.com/<owner>/<repo>.git

HuggingFace: Set HF_ENDPOINT=<URL> env var

6. Restore Official Sources

7. Notes

• Docker & GitHub accelerators have the highest churn rate — always validate before configuring
• If the user has an enterprise Nexus/Artifactory, prefer that over public mirrors
• WSL 1 and WSL 2 have different network stacks; WSL 2 has its own IP and needs separate Docker/apt config
• If HTTP_PROXY / HTTPS_PROXY env vars are set, some tools may bypass mirrors and go through the proxy instead
• On ARM architectures (Apple Silicon, ARM Linux), verify that the mirror hosts packages for your architecture
• When multiple Python/Node versions coexist (pyenv, nvm, conda envs), config may need to target specific environments rather than global settings
• Use scripts/validate.sh or scripts/validate.ps1 for periodic health checks

8. Known Unstable Sources

This section is informational. Always validate before use rather than relying solely on this list, which may itself become outdated.

9. Cross-Agent Adaptation

Capability Requirements

Platform Adaptation

Claude Code / StepFun: Native support. Place folder in ~/.claude/skills/ or ~/.stepfun/skills/.

Cursor: Create .cursor/rules/china-mirror-resolver.mdc with this content:

---
description: Resolve slow package downloads in China by switching to domestic mirrors. Triggers on: timeout, mirror, 换源, 镜像源, 下载慢
globs:
alwaysApply: false
---

[Paste the content of this SKILL.md here, excluding the YAML frontmatter]

Windsurf: Create .windsurf/rules/china-mirror-resolver.md with this content:

---
trigger: auto
---

[Paste the content of this SKILL.md here, excluding the YAML frontmatter]

Generic LLM (no skill system): Include Section 2 (baseline table) and Section 5 (config quick reference) in the system prompt. Skip Section 3 (search) if the LLM has no search tool.