fix(illness): wire P3 engine to UI + OpenAPI, correctness (return-anchor, red-flag, fever, tz), FLARE/edit, guards

src/app/api/illness/episodes/[id]/day-logs/route.ts

@@ -115,11 +115,6 @@ export const POST = apiHandler(
     const tz = user.timezone ?? DEFAULT_TIMEZONE;
     const result = await upsertIllnessDayLog(user.id, id, parsed.data, tz);
 
-    const row = await prisma.illnessDayLog.findUniqueOrThrow({
-      where: { id: result.id },
-      include: dayLogSymptomInclude,
-    });
-
     await auditLog("illness.day-log.upsert", {
       userId: user.id,
       ipAddress: getClientIp(request),
@@ -135,6 +130,6 @@ export const POST = apiHandler(
       meta: { existed: result.existed },
     });
 
-    return apiSuccess(toIllnessDayLogDTO(row), result.existed ? 200 : 201);
+    return apiSuccess(result.dto, result.existed ? 200 : 201);
   },
 );

src/app/api/illness/episodes/[id]/resolve/route.ts

@@ -36,7 +36,13 @@ export const PATCH = apiHandler(
     const { id } = await params;
     const existing = await prisma.illnessEpisode.findUnique({
       where: { id },
-      select: { id: true, userId: true, deletedAt: true, lifecycle: true },
+      select: {
+        id: true,
+        userId: true,
+        deletedAt: true,
+        lifecycle: true,
+        onsetAt: true,
+      },
     });
     if (!existing || existing.userId !== user.id || existing.deletedAt !== null) {
       return apiError("Episode not found", 404);
@@ -63,6 +69,14 @@ export const PATCH = apiHandler(
       ? new Date(parsed.data.resolvedAt)
       : new Date();
 
+    // An episode can never resolve before it began (the inverted-window guard,
+    // checked against the stored onset since the body only carries resolvedAt).
+    if (resolvedAt < existing.onsetAt) {
+      return apiError("resolvedAt must be on or after onsetAt", 422, {
+        errorCode: "illness.episode.invalid-window",
+      });
+    }
+
     const updated = await prisma.illnessEpisode.update({
       where: { id },
       data: { resolvedAt },

src/app/api/illness/episodes/[id]/route.ts

@@ -1,7 +1,8 @@
 /**
  * `GET    /api/illness/episodes/{id}` — one owned, live episode.
  * `PATCH  /api/illness/episodes/{id}` — edit it (partial; field-by-field).
- * `DELETE /api/illness/episodes/{id}` — soft-delete it (idempotent, 204).
+ * `DELETE /api/illness/episodes/{id}` — soft-delete it (idempotent;
+ *          returns `{ deleted: true }`).
  *
  * Born-gated + owner-scoped. `userId` is narrowed from auth and fed to the
  * Prisma `where`; the body never carries it. `note` is encrypted at rest.
@@ -62,7 +63,13 @@ export const PATCH = apiHandler(
     const { id } = await params;
     const existing = await prisma.illnessEpisode.findUnique({
       where: { id },
-      select: { id: true, userId: true, deletedAt: true },
+      select: {
+        id: true,
+        userId: true,
+        deletedAt: true,
+        onsetAt: true,
+        resolvedAt: true,
+      },
     });
     if (!existing || existing.userId !== user.id || existing.deletedAt !== null) {
       return apiError("Episode not found", 404);
@@ -81,6 +88,23 @@ export const PATCH = apiHandler(
     }
     const entry = parsed.data;
 
+    // Window invariant against the MERGED state: a partial edit touching only
+    // one instant is validated against the stored value (the schema already
+    // catches a both-in-body inversion).
+    const mergedOnset =
+      entry.onsetAt !== undefined ? new Date(entry.onsetAt) : existing.onsetAt;
+    const mergedResolved =
+      entry.resolvedAt !== undefined
+        ? entry.resolvedAt
+          ? new Date(entry.resolvedAt)
+          : null
+        : existing.resolvedAt;
+    if (mergedResolved && mergedResolved < mergedOnset) {
+      return apiError("resolvedAt must be on or after onsetAt", 422, {
+        errorCode: "illness.episode.invalid-window",
+      });
+    }
+
     // A re-parent must point at an owned, live episode.
     if (entry.parentConditionId) {
       const parent = await prisma.illnessEpisode.findUnique({
@@ -173,6 +197,8 @@ export const DELETE = apiHandler(
       },
     });
 
-    return new Response(null, { status: 204 });
+    // Standard `{ deleted: true }` envelope (the cross-module DELETE shape) so
+    // the client never has to special-case a bodyless 204 here.
+    return apiSuccess({ deleted: true });
   },
 );

src/app/api/illness/episodes/route.ts

@@ -24,6 +24,7 @@ import {
   safeJson,
 } from "@/lib/api-response";
 import { requireIllnessEnabled } from "@/lib/illness/gate";
+import { withIdempotency } from "@/lib/idempotency";
 import { encryptToBytes } from "@/lib/ai/coach/bytes-codec";
 import {
   illnessEpisodeCreateSchema,
@@ -67,7 +68,12 @@ export const GET = apiHandler(async (request: NextRequest) => {
   return apiSuccess(rows.map(toIllnessEpisodeDTO));
 });
 
-export const POST = apiHandler(async (request: NextRequest) => {
+// `withIdempotency` lets an iOS retry / double-tap re-send the same
+// `Idempotency-Key` without minting a duplicate episode (siblings — labs,
+// measurements — wrap their creates the same way).
+export const POST = apiHandler(withIdempotency<[NextRequest]>(postEpisode));
+
+async function postEpisode(request: NextRequest): Promise<Response> {
   const { user } = await requireAuth();
 
   const gate = await requireIllnessEnabled(user.id);
@@ -135,4 +141,4 @@ export const POST = apiHandler(async (request: NextRequest) => {
   });
 
   return apiSuccess(toIllnessEpisodeDTO(created), 201);
-});
+}

src/app/illness/[id]/page.tsx

@@ -0,0 +1,56 @@
+"use client";
+
+/**
+ * v1.18.1 — per-episode detail page (`/illness/[id]`), mirroring
+ * `/labs/[biomarkerId]`. Born-gated on the resolved `modules.illness` flag;
+ * an unauthenticated visitor is bounced to login, an account without the
+ * module opted in is bounced home (every `/api/illness/*` route also enforces
+ * the gate server-side, so this is a UX redirect, not the security boundary).
+ */
+import { use, useEffect } from "react";
+import { useRouter } from "next/navigation";
+import { Loader2 } from "lucide-react";
+
+import { IllnessEpisodeDetail } from "@/components/illness/illness-episode-detail";
+import { BackLink } from "@/components/ui/back-link";
+import { useAuth } from "@/hooks/use-auth";
+import { useMounted } from "@/hooks/use-mounted";
+import { useTranslations } from "@/lib/i18n/context";
+
+export default function IllnessEpisodePage({
+  params,
+}: {
+  params: Promise<{ id: string }>;
+}) {
+  const { id } = use(params);
+  const { user, isAuthenticated, isLoading } = useAuth();
+  const mounted = useMounted();
+  const router = useRouter();
+  const { t } = useTranslations();
+
+  const enabled = user?.modules?.illness === true;
+
+  useEffect(() => {
+    if (isLoading) return;
+    if (!isAuthenticated) {
+      router.push("/auth/login");
+    } else if (!enabled) {
+      router.push("/");
+    }
+  }, [isLoading, isAuthenticated, enabled, router]);
+
+  if (!mounted || isLoading || !isAuthenticated || !enabled) {
+    return (
+      <div className="flex h-64 items-center justify-center">
+        <Loader2 className="text-primary h-8 w-8 animate-spin motion-reduce:animate-none" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <BackLink href="/illness" label={t("illness.backToList")} />
+      <IllnessEpisodeDetail episodeId={id} />
+    </div>
+  );
+}