Module 6, Lesson 10: Building the Expense Lifecycle (Phase 2)

How do you build a whole phase at once with Claude Code instead of a few issues at a time? You hand Claude Code the entire epic, tell it to review every story and sub-issue underneath it, and have it ask its clarifying questions before touching any of it. Then you let it work through the phase as vertical slices, one small end-to-end piece at a time, committing as it goes, while you manually test each slice on real emulators before calling it done. The full walkthrough is in The Product Path.

How do you batch an entire build phase with Claude Code?

You point Claude Code at the epic instead of individual issues, tell it to review every story and sub-issue underneath it, and ask it to work through the phase by priority as vertical slices rather than building everything at once. You still answer clarifying questions as the product owner, still manually test what Claude Code can't test itself, like a two-user approval flow, and still commit in small chunks. The difference from earlier lessons is scope: one prompt now covers a whole phase instead of a handful of issues.

Where We Are in the Course

Phase 1 (identity and relationships) wrapped in the last lesson, tested in the emulator and on a real device. Two issues stayed in Develop, blocked on an Apple Team ID needed for push notifications, and that's fine to leave unresolved for now. This lesson moves into Phase 2: the expense lifecycle, the actual core feature of the app.

Before We Start

From previous lessons:

• Phase 1 is built and closed out, tested in the emulator and confirmed on a real device. Module 6, Lessons 8 and 9
• You know the batching pattern: group related issues, review as one, ask clarifying questions, confirm the plan, implement, test, commit. Module 6, Lessons 6 and 7
• Your YouTrack Agile board has Phase 2 laid out as an epic with stories and sub-issues underneath it, ready to pick up. Module 3, Lessons 7 and 9

Tools / setup you'll need:

• WebStorm, with your backend (API) and mobile frontend modules open
• Claude Code, with your YouTrack MCP connection active
• Your Android emulator, up and running, plus the ability to spin up a second emulator for two-user testing
• Your local Postgres instance running through Docker Compose

By the end of this lesson, you'll:

• Have handed Claude Code an entire epic, not just a handful of issues, and let it review every story and sub-issue underneath it
• Have chosen vertical slices over building everything at once, and understood why that matters
• Have caught three real bugs by manually testing what Claude Code built, not by trusting its own test run
• Have watched Claude Code add follow-up issues it found on its own and assign them to you
• Have manually tested a two-user approval flow across two emulators, since that's not something Claude Code can test itself

About This Lesson

Duration: ~13 minutes video
Skill Level: Intermediate
What You'll Build: The expense lifecycle for Nurturo: adding an expense, splitting balances between co-parents, approving or disputing an expense, and the notifications that go with it.

This is the first lesson where I hand Claude Code a full phase instead of a few issues at a time. I want to show you both sides of that: it's a faster way to move through a big chunk of work, but it also means more bugs slip through on the first pass, since more is happening at once. I caught three real bugs by manually testing, not by trusting a green test suite, and one story couldn't be marked done at all because it genuinely needs two real users to test properly.