Day 4 at NoteDrop. 48 hours to the investor demo and three tickets still open from earlier in the week: the pgvector staleness fix you scoped on Day 1, the Stripe webhook handler you started on Day 2, and the cosmetic one — the investor's seed-name baked into 4 sample notes for the live demo. You have Sasha. You have three terminal panes. The temptation is to fire all three at once and hope merge time is somebody else's problem. The opinion of this chapter: parallelism is not a question of how many panes fit on your screen, it's a question of which files each branch touches. Pick the wrong split and you'll spend the last 6 hours before the demo doing rebase therapy.
You'll walk out able to
- Use file-overlap (not optimism) as the predicate for whether two tickets can run in parallel
- Order merges by ascending blast radius so any single bad merge is recoverable
- Recognize when adding a fourth parallel worktree HURTS the overall throughput
- Read three tmux panes at once and identify the one that's about to cause a merge conflict
- Spot scope contamination across panes as the strongest 'stop the world' signal
- Write evals that verify each parallel ticket independently plus a regression-guard across all three
Your first task
The parallel scheme
9:02am, Day 4. Three tickets on the board. A: pgvector staleness — touches src/lib/search/* and src/lib/embeddings.ts (the one Sasha's been poking at). B: Stripe webhook handler — touches src/app/api/webhooks/stripe/route.ts and src/lib/stripe.ts. C: investor seed-name in 4 sample notes — touches db/seeds/demo.ts only. You have three worktrees free. Sasha asks the question out loud: 'do we just fire all three?'
What you'll answer
Pick the parallel scheme that actually survives merge time.
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