Ownership: end-to-end
This course follows one feature, Partners, across its footprint: around a hundred files over eleven layers, plus locale keys, storage and queues. It defines owning a feature end to end as knowing every way in, every way it fails, and how you would find out it stopped working. Lessons cover finding entry points and reading before writing code. They also cover deploy order for migrations, checking both languages through I18n and making job failures visible. The last lessons treat inherited code and one worked change, a dark-mode partner logo.
What you'll learn
- ✓Counting a feature's footprint across every layer
- ✓Finding every entry point: routes, jobs, callers, callbacks and rake tasks
- ✓Reading neighbors, finding the seam and planning migrations before writing code
- ✓Deploy order for adding, removing and renaming columns
- ✓Making background job failures countable
- ✓Reading and changing code someone else wrote
The footprint of one feature
Owning a feature end to end starts with knowing how big a feature is. Not in lines: in places you have to touch, and places that can break without you noticing.
Read the full lesson free →Curriculum
7 lessonsThe footprint of one feature
Counts the Partners feature at about a hundred files across eleven layers and defines end-to-end ownership.
Every way in
Traces the two paths into the logo fetch service and why their timing, purge and error reporting differ.
Before you write code
Covers reading neighboring files, confirming the domain, finding the seam, planning migrations and asking how to undo a change.
Shipping it
Explains safe deploy order for column changes, checking locale keys through I18n, and when feature flags are worth it.
After it ships
Shows how a job that discards its Result hides failures, and four ways to find out it broke.
Owning what you did not write
Gives a reading order for unfamiliar features, using git history, changing code safely and asking the previous author.
Putting it together: one change
Walks one change, a dark-mode partner logo, through reading, deciding, slicing, checking layers and observing afterwards.