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.
npx agentmods add rules/yoavaa/design-log-methodology/design-loggit clone --depth 1 https://github.com/yoavaa/design-log-methodologyWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00762 | $0.00762 |
| Opus 5 | $0.00381 | $0.00381 |
| Sonnet 5 | $0.00152 | $0.00152 |
| Haiku 4.5 | $0.00076 | $0.00076 |
Grade A, and why
design-log scanned grade A with 0 findings 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 2d ago.
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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Design Log Methodology
The project follows a rigorous design log methodology for all significant features and architectural changes.
Before Making Changes
- Check design logs in
./design-log/for existing designs and implementation notes - For new features: Create design log first, get approval, then implement
- Read related design logs to understand context and constraints
When Creating Design Logs
- Structure: Background → Problem → Questions and Answers → Design → Implementation Plan → Examples → Trade-offs
- Be specific: Include file paths, type signatures, validation rules
- Show examples: Use ✅/❌ for good/bad patterns, include realistic code
- Explain why: Don't just describe what, explain rationale and trade-offs
- Ask Questions (in the file): For anything that is not clear, or missing information
- When answering question: keep the questions, just add answers
- Be brief: write short explanations and only what most relevant
- Draw Diagrams: Use mermain inline diagrams when it makes sense
- Define verification criteria: how do we know the implementation solves the original problem
When Implementing
- Follow the implementation plan phases from the design log
- Write tests first or update existing tests to match new behavior
- Do not Update design log initial section once implementation started
- Append design log with "Implementation Results" section as you go
- Document deviations: Explain why implementation differs from design
- Run tests: Include test results (X/Y passing) in implementation notes
- After Implementation add a summary of deviations from original design
When Answering Questions
- Reference design logs by number when relevant (e.g., "See Design Log #50")
- Use codebase terminology: ViewState, Contract, JayContract, phase annotations
- Show type signatures: This is a TypeScript project with heavy type usage
- Consider backward compatibility: Default to non-breaking 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.
- 2d ago First seen · 62 lines · 762 tokens per session scan A 6a90dd7aa012
design-log is a cursor rule published in the GitHub repository yoavaa/design-log-methodology (42 stars, last pushed 4mo ago), licensed MIT. It adds 762 tokens to every session, about $0.0038 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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