Symmetric Dogfooding

Bidirectional integration validation pattern where two repositories each consume the other for testing, ensuring both sides work correctly together before downstream adoption.

Pattern Overview

┌─────────────────────────────────────────────────────────────────┐ │ SYMMETRIC DOGFOODING │ │ │ │ Repo A ◄─────── mutual validation ───────► Repo B │ │ │ │ EXPORTS: EXPORTS: │ │ - Library/API - Library/API │ │ - Data structures - Data structures │ │ │ │ VALIDATES WITH: VALIDATES WITH: │ │ - Repo B real outputs - Repo A real outputs │ │ - Production-like data - Production-like data │ │ │ └─────────────────────────────────────────────────────────────────┘

When to Use This Skill

Use this skill when:

• Two repos have a producer/consumer relationship

• APIs evolve independently and need integration testing

• Data formats may drift between repos

• Both repos are actively developed

TodoWrite Task Templates

Template A: Setup Symmetric Dogfooding Between Two Repos

1. Identify integration surface (exports from A consumed by B and vice versa)
2. Document data formats, schemas, API signatures at boundary
3. Configure cross-repo dev dependencies in both repos
4. Pin versions explicitly (tags or SHAs, never main)
5. Create integration/ test directory in both repos
6. Write bidirectional validation tests (A validates with B outputs, B validates with A outputs)
7. Add validation tasks to mise.toml or Makefile
8. Document pre-release protocol in both CLAUDE.md files
9. Run full symmetric validation to verify setup
10. Verify against Symmetric Dogfooding Checklist below

Template B: Pre-Release Validation

1. Run validate:symmetric task in releasing repo
2. Check if other repo has pending changes affecting integration
3. If yes, test against other repo's feature branch
4. Document any failures in validation log
5. Fix integration issues before release
6. Update version pins after successful validation
7. Coordinate if breaking changes require simultaneous release
8. Verify against Symmetric Dogfooding Checklist below

Template C: Add New Integration Point

1. Identify new export/import being added
2. Update integration surface documentation
3. Add tests in both repos for new integration point
4. Run symmetric validation in both directions
5. Update version pins if needed
6. Verify against Symmetric Dogfooding Checklist below

Symmetric Dogfooding Checklist

After ANY symmetric dogfooding work, verify:

• Both repos have integration tests that import the other

• Version pins are explicit (tags or commit SHAs)

• Pre-release checklist includes cross-repo validation

• Integration tests use real data (not mocks of the other repo)

• Breaking changes coordination documented

• Validation task runnable via single command

Post-Change Checklist (Self-Maintenance)

After modifying THIS skill:

• Templates cover common symmetric dogfooding scenarios

• Checklist reflects current best practices

• Example in references/ still accurate

• Append changes to evolution-log.md

Implementation Guide

Phase 1: Discovery and Mapping

Identify the integration surface:

• List all exports from Repo A consumed by Repo B

• List all exports from Repo B consumed by Repo A

• Document data formats, schemas, API signatures

Map validation scenarios:

• What real-world data from B can validate A outputs?

• What real-world data from A can validate B outputs?

• Identify edge cases that only appear in production usage

Phase 2: Dependency Configuration

Configure cross-repo dev dependencies:

Python (uv/pip):

Repo A pyproject.toml

[project.optional-dependencies] validation = ["repo-b"]

[tool.uv.sources] repo-b = { git = "https://github.com/org/repo-b", tag = "<tag>" } # SSoT-OK

Repo B pyproject.toml

[project.optional-dependencies] validation = ["repo-a"]

[tool.uv.sources] repo-a = { git = "https://github.com/org/repo-a", tag = "<tag>" } # SSoT-OK

Rust (Cargo):

[dev-dependencies] repo-b = { git = "https://github.com/org/repo-b", tag = "<tag>" } # SSoT-OK

Node.js:

{ "devDependencies": { "repo-b": "github:org/repo-b#<tag>" } }

Critical: Pin to tags or commit SHAs. Never use main/master branches.

Phase 3: Test Infrastructure

Directory structure in both repos:

repo-a/ └── tests/ ├── unit/ # Internal tests └── integration/ # Tests using repo-b real outputs └── test_with_repo_b.py

repo-b/ └── tests/ ├── unit/ # Internal tests └── integration/ # Tests using repo-a real outputs └── test_with_repo_a.py

Bidirectional validation test pattern:

repo-a/tests/integration/test_with_repo_b.py

"""Validate Repo A outputs work correctly with Repo B inputs."""

def test_a_output_consumed_by_b(): # Generate output using Repo A a_output = repo_a.generate_data()

# Feed to Repo B - should work without errors
b_result = repo_b.process(a_output)

# Validate the round-trip
assert b_result.is_valid()

Phase 4: Task Automation

mise.toml example:

[tasks."validate:symmetric"] description = "Validate against partner repo" run = """ uv sync --extra validation uv run pytest tests/integration/ -v """

[tasks."validate:pre-release"] description = "Full validation before release" depends = ["test:unit", "validate:symmetric"]

Phase 5: Pre-Release Protocol

Before releasing Repo A:

• Run validate:symmetric in Repo A (tests against current Repo B)

• If Repo B has pending changes, test against Repo B branch too

• Update version pins after successful validation

Before releasing Repo B:

• Run validate:symmetric in Repo B (tests against current Repo A)

• If Repo A has pending changes, test against Repo A branch too

• Update version pins after successful validation

Coordinating breaking changes:

• If A needs to break compatibility, update B first

• If B needs to break compatibility, update A first

• Consider simultaneous releases for tightly coupled changes

Anti-Patterns

Anti-Pattern Problem Solution

One-direction only Misses half the bugs Always test both directions

Using main branch Unstable, breaks randomly Pin to tags or SHAs

Skipping for small changes Small changes cause big breaks Always run full validation

Mocking partner repo Defeats the purpose Use real imports

Ignoring version matrix Silent production failures Maintain compatibility matrix

References

• example-setup.md - Real-world trading-fitness/rangebar-py example

• evolution-log.md - Skill change history

External:

• Dogfooding (DevIQ)

• CDC Testing (Microsoft)

Troubleshooting

Issue Cause Solution

Dependency resolution fails Version pin outdated Update tag/SHA pin to latest stable version

Tests pass locally fail CI Different partner repo version Pin exact same version in both environments

Breaking change not caught One-direction testing only Run validate:symmetric in BOTH repos

Integration surface unclear Undocumented exports Map all imports/exports before setting up tests

Too many parts moving Uncoordinated releases Coordinate breaking changes, test branches first

Mock data hiding bugs Using stubs instead of real Always import real partner repo for integration

Version matrix explosion Too many combinations Limit support to N-1 versions, document clearly

Circular dependency Both repos require each other Use optional-dependencies for validation only