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/markmhendrickson/foundation/test_first_workflowgit clone --depth 1 https://github.com/markmhendrickson/foundationWhat 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 | $0.00023 | $0.01917 |
| Opus 5 | $0.00012 | $0.00958 |
| Sonnet 5 | $0.00005 | $0.00383 |
| Haiku 4.5 | $0.00002 | $0.00192 |
Grade A, and why
test_first_workflow 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 yesterday.
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 — 341 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-First Workflow Rules
Reference: Repository testing standards
Purpose
Enforces test-first (TDD) or test-alongside development workflow to catch bugs early and ensure comprehensive test coverage.
Scope
This document covers:
- Test-first workflow requirements
- Test writing alongside implementation
- Test execution before implementation verification
- Test coverage verification
This document does NOT cover:
- Test execution after implementation (see
agent_test_execution.mdc) - Test quality standards (see repository test quality rules)
Trigger Patterns
Agents MUST follow test-first workflow when:
- Implementing new features
- Adding new functions or methods
- Creating new API endpoints
- Building new UI components
- Adding new database operations
Test-First Workflow
Option 1: Pure TDD (Test-Driven Development)
For new features or significant changes:
-
Write test cases FIRST
- Create test file before implementation file
- Write test cases covering:
- Happy path
- Edge cases (null, empty, invalid values)
- Error cases
- Boundary conditions
-
Run tests to verify they fail (RED)
- Tests should fail because implementation doesn't exist
- This confirms tests are actually testing something
-
Implement feature to make tests pass (GREEN)
- Write minimal code to make tests pass
- Don't over-engineer
-
Refactor if needed (REFACTOR)
- Improve code quality while keeping tests green
- Verify tests still pass after refactoring
Option 2: Test-Alongside Development
For smaller changes or when TDD is impractical:
-
Write test cases alongside implementation
- Create test file at same time as implementation
- Write tests for each function as you implement it
- Don't defer test writing
-
Run tests frequently
- Run tests after each function implementation
- Fix failures immediately
- Verify tests pass before moving on
-
Ensure comprehensive coverage
- Test happy path
- Test edge cases
- Test error cases
- Verify all code paths covered
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.
- yesterday First seen · 341 lines · 23 tokens per session scan A 7dab94c97bb1
test_first_workflow is a cursor rule published in the GitHub repository markmhendrickson/foundation (2 stars, last pushed 1mo ago), licensed MIT. It adds 23 tokens to every session and 1,917 once invoked, about $0.0001 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 2026-08-31.
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