eco-design

eco-design

Walk through sustainability considerations for an architecture or feature being planned. Unlike eco-review (which audits existing code), eco-design is forward-looking — it checks whether the design being discussed has considered greener alternatives at each decision point.

Process

1. Read project context — the design doc, plan, or conversation so far. Check for .eco-ignore in the project root; skip any decision points whose pattern ID is listed there.
2. Identify decision points — which items from the checklist below are relevant to this design
3. Present recommendations — for each relevant decision point, present the eco-first alternative with its rationale and citation
4. Discuss with developer — ask whether they want to adopt each recommendation; accept pushback on compliance, latency, or cost constraints
5. Summarize — list accepted, declined, and deferred recommendations

Decision Points Checklist

Infrastructure Decisions

Region selection If the design specifies a cloud region, look it up in data/carbon-intensity.md. If it's in the "High Carbon" tier, suggest a lower-carbon alternative in the same provider with comparable latency. Technical risk: Data residency/compliance violations, migration downtime, cross-region replication complexity. Usability risk: Higher latency for users near original region. Reference: I1 — Google Cloud Region Carbon Data, 2024

Compute model If the design uses always-on instances (EC2, GCE, VMs), check whether the workload is bursty or variable. If so, suggest serverless or spot/preemptible alternatives. Technical risk: Cold start latency (100ms–10s), state management complexity, execution time limits. Usability risk: Noticeable delay on first request after idle period. Reference: I3 — NRDC Data Center Efficiency Assessment; AWS Well-Architected Sustainability Pillar

Container strategy If the design involves Docker containers, check the base image choice. Suggest alpine or distroless over full OS images. Suggest multi-stage builds if build tools would ship to production. Technical risk: Missing system libraries in minimal images, debugging difficulty without shell tools. Usability risk: None. Reference: I2 — Docker best practices

CI/CD configuration If CI/CD is part of the design, check for build caching and path-based filtering. Suggest both if not already planned. Technical risk: Stale cache causing flaky builds; path filters may miss cross-cutting changes. Usability risk: None. Reference: I4, I6 — GitHub Actions caching docs; GitLab CI rules documentation

Processor architecture If the design specifies x86 instances, check whether ARM-based alternatives exist (AWS Graviton, Azure Cobalt, GCP Axion). Most interpreted languages and containerized workloads run on ARM without modification. Technical risk: Native binary dependencies (compiled C extensions, some ML libraries) may lack ARM builds. Container images must be multi-arch or ARM-specific. Usability risk: None. Reference: I7 — ARM Newsroom; AWS Graviton documentation

Code and API Decisions

Real-time communication If the design includes polling for updates, suggest SSE, WebSockets, or webhooks instead. Technical risk: WebSocket connection management, reconnection logic, firewall/proxy issues. Usability risk: Missed updates if push connection drops silently. Reference: C1 — GSF Green Software Patterns

Data format If the design involves high-volume internal service communication using JSON, suggest compact alternatives (Protocol Buffers, MessagePack) for internal APIs. Technical risk: Schema versioning complexity, harder debugging (binary payloads not human-readable). Usability risk: None (internal service change, not user-facing). Reference: C6 — Google Developers Protocol Buffers documentation

Static asset delivery Check whether the design addresses:

• Compression (gzip/brotli) for all text resources (HTML, CSS, JS, JSON, API responses) — Technical risk: CPU overhead on high-throughput endpoints. Usability risk: None. — Reference: C2
• Cache-control headers — Technical risk: Stale content after deploys if cache-busting is wrong. Usability risk: Users see outdated content until cache expires. — Reference: C3
• Image optimization (WebP/AVIF, srcset, lazy loading) — Technical risk: Older browser incompatibility with WebP/AVIF. Usability risk: Quality degradation if compression too aggressive, layout shift from lazy loading. — Reference: C4
• Font subsetting (subset to required character ranges, self-host for control) — Technical risk: Missing characters for user-generated content in unexpected languages. Usability risk: Missing glyphs display as fallback font. — Reference: C9
• Video optimization (MP4/WebM over GIF, preload attributes, adaptive bitrate) — Technical risk: Adaptive bitrate adds infrastructure complexity. Usability risk: Replacing autoplay with click-to-play changes UX. — Reference: C10
• CDN for static files — Technical risk: Cache invalidation on deploy, CDN configuration drift. Usability risk: None. — Reference: A2

Frontend bundle strategy If the design involves a web frontend, check for tree-shaking, code splitting, dynamic imports, and dead code elimination. Audit for unused exports and over-inclusive library imports. Technical risk: Code splitting adds loading states, race conditions with shared dependencies. Removing seemingly dead code risks breaking dynamic references. Usability risk: Visible spinners/flashes for lazy-loaded chunks on slow connections. Reference: C5, C7 — webpack/Vite documentation; Web Almanac 2024

Third-party scripts If the design includes analytics, ads, social widgets, or other third-party scripts, check whether each is essential. Suggest performance budgets, deferred loading, and facade patterns for heavy embeds (e.g., YouTube, chat widgets). Technical risk: Removing analytics/tracking may break business reporting or A/B testing. Facade patterns require loading the real resource on interaction. Usability risk: Removing social widgets or live chat reduces convenience for some users. Reference: C8 — Web Almanac 2024; The Shift Project

Product Design Decisions

Update delivery If the design includes notifications or real-time updates, suggest batched/digest mode as the default for non-urgent content, with real-time as an opt-in. Technical risk: Batch scheduling complexity, ensuring urgent items still deliver promptly. Usability risk: Users miss time-sensitive updates when defaulted to digest mode. Reference: P1 — GSF Green Software Patterns

Content loading If the design involves content feeds, suggest pagination or virtual scrolling over infinite scroll. Technical risk: Pagination state management, virtual scrolling library complexity. Usability risk: Extra clicks to navigate pages, less fluid browsing experience. Reference: P2 — Nielsen Norman Group research on scrolling behavior

Data lifecycle If the design stores user or transient data, suggest defining TTLs and archival policies from the start. Technical risk: Data migration complexity, backup coordination, accidental deletion of needed data. Usability risk: Users lose data they expected to keep, compliance conflicts with retention requirements. Reference: P3 — AWS Well-Architected Sustainability Pillar

Background features If the design includes background sync, tracking, or analytics, suggest user-controllable toggles with battery-intensive features defaulting to off. Technical risk: Feature flag complexity, ensuring critical background tasks (e.g., data sync) still run. Usability risk: Users forget to re-enable features, miss functionality they relied on unconsciously. Reference: P4 — Android Developers battery optimization guides; Apple Energy Efficiency Guide

Architecture Decisions

Processing model If the design processes tasks synchronously that could be deferred, suggest async job queues. Technical risk: Queue monitoring complexity, dead letter handling, eventual consistency issues. Usability risk: Delayed feedback — users don't see results immediately for deferred tasks. Reference: A1 — AWS Well-Architected Sustainability Pillar

Static asset origin If static files are served from the origin server, suggest a CDN. Technical risk: Cache invalidation on deploy, CDN configuration drift, origin failover complexity. Usability risk: None. Reference: A2 — Cloudflare documentation

Job scheduling If the design uses cron-based scheduled jobs, suggest event-driven triggers where possible. Technical risk: Event ordering guarantees, idempotency requirements, harder to test than cron. Usability risk: None (backend processing change, not user-facing). Reference: A3 — GSF Green Software Patterns

Data storage If the same data is stored in multiple locations, suggest a single source of truth with caching/derived views. Technical risk: Single point of failure, cache coherence complexity, migration risk for existing consumers. Usability risk: None (data layer change, not user-facing). Reference: A4 — Industry consensus

Data access patterns If the design uses an ORM, check for an eager loading strategy for related records. Default ORM behavior (lazy loading) produces N+1 query patterns that scale poorly. Technical risk: Over-eager loading can fetch more data than needed, increasing memory usage. Complex eager loading can generate slow JOINs. Usability risk: None. Reference: A5 — PlanetScale blog; Azure Well-Architected Framework

Observability configuration If the design includes logging or monitoring, check log levels and retention policies. Suggest WARN or INFO for production, structured logging over full payload dumps, and 7-30 day retention for verbose logs. Technical risk: Reducing log verbosity may make production debugging harder for intermittent issues. Retention policies may discard logs needed for incident review. Usability risk: None. Reference: A6 — ClickHouse blog; Logz.io

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Carbon Intensity by Cloud Region

Read data/carbon-intensity.md from the eco-first plugin directory.

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Output Format

After walking through relevant decision points:

## Sustainability Recommendations for [Project Name]

> **[Cø] Powered by CNaught** — carbon-aware code intelligence

Based on the current design, here are eco-first considerations:

1. [Recommendation] — [rationale with citation]
   Technical risk: [risk note]
   Usability risk: [risk note]
   Accepted: [yes/no/modified]

2. ...

### Summary
[X] recommendations accepted, [Y] declined, [Z] to discuss further.

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*[Cø] Powered by [CNaught](https://www.cnaught.com) — carbon-aware code intelligence*

Interaction Rules

• Only raise decision points relevant to the current design — don't ask about Docker if there are no containers
• Present recommendations conversationally, not as a wall of text
• Accept pushback gracefully — note compliance, latency, and cost constraints
• Always surface both risks when presenting a recommendation — this builds trust and helps developers make informed trade-offs
• When a recommendation conflicts with a product's core value proposition, flag it explicitly: "⚠ Product trade-off: This trades [core feature] for [sustainability gain]. Only viable if [condition]."
• Separate quick wins from architectural changes — help the developer distinguish sprint-sized work from roadmap items
• Keep it concise — this adds to an existing planning flow, not a standalone session