One real ride

Seven incidents where every automated gate was green and the feature was broken in production or the UI, plus a schema change that broke every report for five days while tsc and the whole test suite stayed green. The pattern is always the same: each layer was proven alone, and the defect lived in a seam between them. Layer: the done-gate hub.

The rule

Before "done": one real end-to-end invocation of the changed path, through the real seams — the deployed function (not the local one), a real authenticated session (not a service-role shortcut), the real model call, the real browser or the real device. The smoke proves the layer; the ride proves the seams.

What counts as a seam

• Deployed runtime vs local: a deployed Edge Function 500'd on a dropped column CI could not see.
• Auth: a function's own role pre-check was wrong in a way its smoke structurally could not catch.
• Type-check vs render: "tsc green is not a working UI" — twice, including a Rules-of-Hooks blank page.
• Build vs dev server: they run different code paths; a green production build does not prove the dev server boots, and vice versa.
• Merge vs ship: know the deploy path per change type — a server merge may be live in minutes while an app merge reaches nobody until the next signed build. A merge is never a device test; the device test is the gate for device- or WebView-specific code.
• Inherited guards and configs: anything borrowed from a sibling surface was calibrated for its original inputs — the first real invocation is what catches the mis-calibration three reviews missed.
• Schema: after any migration existing code reads, ride the highest-value path once (generate the report, make the request). It is the only check that catches what synthetic-data tests cannot.

Routes

• Interpreting any individual success signal during the ride → verify-the-effect (the norm; its playbook holds the diagnostics discipline).
• The change sends transactional email → email-delivery-verification.
• The change involved env vars, CI secrets, or hosted config → env-change-verification.
• The change touched build config, lockfiles, or toolchain → reproduce-the-real-build.

What this skill does not do

It does not replace tests, smokes, or catalog verification — it is the last gate after them, not a substitute. It does not fire on library-internal changes with no deployed surface.

Why

Integration bugs live only in the seams, and every seam incident in the corpus was discovered by a user or a first real invocation — never by the green board. Evidence: PropOS LESSONS_LEARNED Sessions 13, 19, 23, 27, 43, 2026-07-05, 2026-07-11; ASH LESSONS_LEARNED 2026-05-27, 2026-07-11.

Additions from the misses-log sweep (2026-10-22)

• A deploy record names the tree it gated. Before each deploy, check the tree against the gated range (git diff --name-only <base> HEAD prints only that wave's paths); two waves on one base deploy one at a time. (AI domain L-103.)