subagents-discipline

Implementation Discipline

Core principle: Test the FEATURE, not just the component you built.

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Three Rules

Rule 1: Look Before You Code

Before writing code that touches external data (API, database, file, config):

1. Fetch/read the ACTUAL data - run the command, see the output
2. Note exact field names, types, formats - not what docs say, what you SEE
3. Code against what you observed - not what you assumed

This catches: field name mismatches, wrong data shapes, missing fields, format differences.

WITHOUT looking first:
  Assumed: column is "reference_images"
  Reality: column is "reference_image_url"
  Result:  Query fails

WITH looking first:
  Ran: SELECT column_name FROM information_schema.columns WHERE table_name = 'assets';
  Saw: reference_image_url
  Coded against: reference_image_url
  Result: Works

Rule 2: Test Both Levels

Component test catches: logic bugs, edge cases, type errors Feature test catches: integration bugs, auth issues, data flow problems

Both are required. Component test alone is NOT sufficient.

You built	Component test	Feature test
API endpoint	curl returns 200	UI calls API, displays result
Database change	Migration runs	App reads/writes correctly
Frontend component	Renders, no errors	User can see and interact
Full-stack feature	Each piece works alone	End-to-end flow works

The pattern:

1. Build the thing
2. Component test - verify your piece works in isolation
3. Feature test - verify the integrated feature works end-to-end
4. Only then claim done

Rule 3: Use Your Tools

Before claiming you can't fully test:

1. Check what MCP servers you have access to - list available tools
2. If any tool can help verify the feature works, use it
3. Be resourceful - browser automation, database inspection, API testing tools

"I couldn't test the feature" is only valid after exhausting available options.