gc-check-sustainability

name	gc-check-sustainability
description	Quick sustainability check on a project or codebase. Evaluates WSG compliance, green hosting, and code-level green patterns. Use when the user asks for a fast sustainability review without a full audit.
license	MIT
metadata	{"author":"fullo","version":"1.2"}

Check Sustainability

Run a quick sustainability check on the current project. For a full 9-phase audit, use /gc-setup.

Steps

1. WSG quick scan

Review the codebase against the most impactful W3C Web Sustainability Guidelines:

• 3.2 Minified and compressed assets?
• 3.3 Unused CSS/JS removed?
• 3.5 Lazy loading for non-critical resources?
• 3.7 Appropriate caching headers?
• 3.15 HTTP/2 or HTTP/3?
• 4.3 Green hosting provider?
• 4.5 CDN or edge caching?
• 2.7 Dark mode / prefers-color-scheme support?
• 2.15 System font stack or minimal web fonts?

If a wsg-compliance.json file exists, use the wsg_compliance_score MCP tool with filePath pointing to the JSON file. The file must be a JSON array of objects with id, status (full/partial/gap/na), and category fields. Otherwise, produce a quick manual assessment.

2. Green hosting check

• Use the check_green_hosting MCP tool with domain (e.g., "example.com" — protocols and paths are stripped automatically)
• If MCP is not available: check manually at Green Web Foundation
• Look for a carbon.txt file at the domain root

3. Code-level green patterns

Pick 3-5 source files (busiest modules, largest files, entry points) and:

• Use the creedengo_check MCP tool with filePath (absolute path to source file). Supports JS/TS, PHP, Python — language is auto-detected from extension
• If MCP is not available: manually check for:
  • Unnecessary DOM manipulation in loops
  • Missing pagination on large queries
  • Synchronous blocking operations
  • Oversized images or unoptimized media
  • Unused dependencies

4. Report

## Sustainability Quick Check

### WSG Compliance
| Guideline | Status | Notes |
|-----------|--------|-------|
| 3.2 Minification | pass/fail | ... |
| ... | ... | ... |

Score: ?/9 guidelines checked

### Green Hosting
- Domain: [domain]
- Green hosted: yes/no
- carbon.txt: found/not found
- Provider: [name]

### Code Patterns
| File | Issues found | Severity |
|------|-------------|----------|
| ... | ... | high/medium/low |

### Top 5 Recommendations
1. [highest impact action]
2. ...

### Methodology and sources
- WSG standard: [W3C Web Sustainability Guidelines 1.0](https://www.w3.org/TR/web-sustainability-guidelines/)
- Green hosting check: [The Green Web Foundation API](https://www.thegreenwebfoundation.org/) — database date [date]
- Code rules: [Creedengo](https://github.com/green-code-initiative/creedengo-rules-specifications) green code rules
- carbon.txt: [carbontxt.org](https://carbontxt.org/) standard

4b. Cheap wins (optional, public sites only)

Two no-measurement checks adapted from The Website Specification that reduce agent-traffic and retry waste:

• /llms.txt + Markdown endpoints — does the site expose a curated Markdown index? Agents reading Markdown instead of rendered HTML+JS transfer a fraction of the bytes.
• Correct error status codes — do 404/500 pages return the right HTTP status (not a 200 with an error body)? A soft-404 makes crawlers retry indefinitely.

These complement the green checks above; they do not change the WSG score.

Gotchas

• Green hosting databases are incomplete: The Green Web Foundation dataset doesn't cover all hosting providers. A "not green" result may mean "not in the database" rather than "definitely not green."
• WSG compliance is self-assessed: There is no official W3C certification for WSG compliance. Any score is an estimate based on available checks, not an official rating.
• Page weight is not the only emissions driver: A lightweight page served from a high-carbon grid can emit more than a heavier page from a green-hosted, edge-cached CDN. Consider the full SWD model, not just transfer size. The emerging SCI for Web standard (GSF × W3C, Q1 2026) formalizes this by attributing emissions across servers, networks, third parties, and end-user devices — record boundaries and data sources so results stay comparable.
• WSG is heading to W3C Statement status: The Web Sustainability Guidelines reached finalised Draft Note (Dec 2025) and are targeting full W3C Statement status around Earth Day (22 Apr 2026). Guideline IDs are stable, so checks here remain valid.

Post-report verification

After presenting the sustainability check report, automatically run /gc-verify in quick mode. This triggers a Chain-of-Verification (CoVe) process: extract claims from the report, generate adversarial questions, answer each independently, and present findings under a ## Verification (CoVe) heading.

Notes

• This is a quick check, not a comprehensive audit
• For detailed WSG compliance (all 80 guidelines), use /gc-setup
• For carbon measurement, use /gc-measure-sci
• For page-level emissions, use /gc-estimate-emissions