A deep link is a reproducible route to app state only when inputs are validated and test data exists. Keep routing separate from parsing and from data loading.

Incoming URL → Validate fields → Resolve route → Render state
  1. 1Incoming URL
  2. 2Validate fields
  3. 3Resolve route
  4. 4Render state

Work through the example

Use a synthetic identifier and an explicit not-found state. Do not place account tokens in screenshot URLs.

Start with a disposable branch and synthetic data. Write the expected outcome before changing the implementation, then keep the first failing result. This prevents a later repair from quietly redefining the task. The procedure below is grounded in the repository reference; its examples must still be checked against your project and installed toolchain.

Implementation reference

The following focused section is adapted from the maintained project guide. It preserves the source’s examples and limitations.

Load this when: adding navigation to more than two screens, handling a URL scheme or universal link, restoring navigation state across launches, or reviewing anything that mutates a NavigationPath.

docs/swiftui/navigation.md covers the navigation APIs. patterns/coordinator.md covers the coordinator pattern. This document covers the piece that breaks in production: making a single typed route model the only way navigation state changes, so a deep link, a button tap, and a restored session all go through the same code.

Acceptance and failure review

Checkpoint What to inspect If it does not match
Incoming URL Confirm the input and environment Preserve the failure and return to this step
Validate fields Inspect the intermediate artifact Preserve the failure and return to this step
Resolve route Run the focused check Preserve the failure and return to this step
Render state Record the observed result Preserve the failure and return to this step

Ask the agent to explain the smallest change that resolves the observed mismatch. Keep unrelated refactors out of the repair. A change that makes a warning disappear is not enough if the behavior or ownership contract has changed. Re-run the same acceptance check so the before and after results are comparable.

Evidence and limits

Custom URL routing and universal-link association are different checks; one does not validate the other.

This is an educational guide. Its presence in the series does not certify a completed client-specific lab. The series evidence record separates executed checks from exercises and blocked environments.

Inspect the source used in this lesson.

What to do next

Next: Localization with an agent: what to check before it "translates" everything