How We Keep a Trunk-Based Pipeline From Being Reckless

Part 1 covered the mechanism: a fingerprint gate decides whether a change ships in minutes over-the-air or needs a full store release. But a gate that only checks "is this native-safe" says nothing about whether the change is good . If every merge to main can reach production within minutes, your safety net can't be a release train that gives everyone time to notice a problem before it ships — it has to be built into the pipeline itself, because there's no train to catch it on the way out. The PR gate Every pull request into main runs through the same automated gate before it's mergeable: a type check, a lint pass, an automated test suite, and end-to-end checks against a real device build. None of that is negotiable — it's the floor, not a nice-to-have. E2E is a big enough topic on its own — closing the loop between what a unit test can see and what actually happens on a phone in someone's hand — that it deserves its own dedicated post rather than a paragraph here. jobs : typecheck : run : npm run typecheck lint : run : npm run lint test : run : npm test e2e : run : npm run e2e Nothing exotic under the hood — ESLint for the lint pass, Husky for local pre-commit/pre-push hooks so the same checks catch you before CI even runs, Jest as the test runner, and React Native Testing Library for component-level tests. Popular, boring, well-documented tooling on purpose — the pipeline's value is in how these are wired together and gated, not in any one tool being clever. Feature flags are the real safety valve Here's the entry condition that makes OTA-from- main safe at all: shipping code and releasing a feature are two different actions. A merge can put new code on every user's device within minutes — that's deploy. Whether that code actually does anything visible is a separate switch, controlled by a remote feature flag, not by whether the code merged. That decoupling is what makes trunk-based development survivable. Nobody has to get the timing of a merge exactly right, bec