Tighten the setup flow after a review of the whole diff

The done screen moves focus to its heading like every other screen; the
confirm screen's preference list holds only dt/dd pairs and the settings
link stands beside it; Back from Q1 is not offered once the flow has
been entered, because the front door would resume past the welcome and
bounce straight back; the medication task records no target on the
ledger, as the contract says, and keeps the id on the screen; and the
two success affordances go through the outcome module rather than a
hand-rolled tick. The error-code catalogue lists the answers and restart
codes and no longer the retired step ones, and the session-surface guard
learns the one new deriving helper the onboarding pages read through.

src/lib/onboarding/wizard-steps.ts

@@ -14,7 +14,6 @@
 import type { OnboardingSourceKey } from "./needs";
 import {
   hasEnteredOnboardingFlow,
-  ONBOARDING_STEP_IDS,
   type OnboardingFirstResultTask,
   type OnboardingNeeds,
   type OnboardingStateDto,
@@ -23,17 +22,6 @@ import {
 
 export type OnboardingScreenId = "welcome" | OnboardingStepId;
 
-export const ONBOARDING_SCREEN_IDS: readonly OnboardingScreenId[] = [
-  "welcome",
-  ...ONBOARDING_STEP_IDS,
-];
-
-export function isOnboardingScreenId(
-  value: string,
-): value is OnboardingScreenId {
-  return (ONBOARDING_SCREEN_IDS as readonly string[]).includes(value);
-}
-
 /**
  * The Q4 sources whose connection the browser can finish on its own — an
  * OAuth handshake or a URL-plus-secret form on Settings → Integrations.

src/lib/openapi/error-codes.ts

@@ -234,15 +234,13 @@ export const ERROR_CODE_CATALOGUE: Readonly<Record<string, readonly string[]>> =
       "nutrient.water.invalid_day",
     ],
     onboarding: [
+      "onboarding.answers.invalid",
+      "onboarding.answers.rateLimited",
       "onboarding.complete.invalid",
       "onboarding.disclaimer.invalid",
-      "onboarding.step.completed",
-      "onboarding.step.concurrent",
-      "onboarding.step.invalid",
-      "onboarding.step.outOfOrder",
-      "onboarding.step.rateLimited",
+      "onboarding.restart.invalid",
+      "onboarding.restart.rateLimited",
       "onboarding.tour.invalid",
-      "onboarding.user.notFound",
     ],
     personal_records: ["personal_records.invalid_query"],
     practitioner: ["practitioner.invalid"],

src/lib/query-keys/onboarding.ts

@@ -18,12 +18,12 @@ export const onboardingKeys = {
   /** `POST /api/onboarding/disclaimer` — the one-time acknowledgment. */
   onboardingDisclaimerMutation: () => ["onboarding", "disclaimer"] as const,
   /**
-   * The latest reading of one type, read back after the first-result step
+   * The latest reading of one area, read back after the first-result step
    * logged it so the screen can show the value on its tile. Rides under the
    * `["measurements"]` prefix so `measurementDependentKeys` evicts it.
    */
-  onboardingLatestReading: (type: string) =>
-    ["measurements", "onboarding-latest", type] as const,
+  onboardingLatestReading: (area: string) =>
+    ["measurements", "onboarding-latest", area] as const,
   /**
    * The upcoming-visit count the checklist's "prepare the visit" row reads
    * off the visits list's meta. Its own key under the `["encounters"]`