fix(fhir): stop advertising a credential no client can obtain

The capability descriptor named `fhir:read` as the scope a narrow token needs
for the REST face. No code path mints a token carrying it — every mint grants a
wildcard, the medication ingest scope, or an MCP scope — so the face is
reachable by the owner's cookie session or a wildcard device token and by
nothing else. Advertising an unobtainable credential invites a client to go
looking for one. The constant stays where it belongs, as the fail-closed check
each route makes; the descriptor now reports the fact instead.

End-to-end coverage for the scope picker: the first run opens it expanded with
the fenced tier rendered and no group control over it, a group row clears the
44 px floor at 390 px, and a leaf grid opens from its chevron. All on stable
test ids rather than text a breakpoint can hide.

src/app/api/meta/capabilities/__tests__/route.test.ts

@@ -53,7 +53,6 @@ import {
   GERMAN_ATC_DEFAULT_LOCALES,
 } from "@/lib/fhir/build-bundle";
 import {
-  FHIR_READ_SCOPE,
   FHIR_REST_RESOURCE_TYPES,
   FHIR_EVERYTHING_OPERATION,
   FHIR_SEARCH_PARAMS,
@@ -87,7 +86,7 @@ type CapabilitiesBody = {
       snomedRoute: string;
       germanAtcDefaultLocales: string[];
       restBaseUrl: string;
-      readScope: string;
+      scopeMintable: boolean;
       resourceTypes: string[];
       operations: string[];
       searchParams: string[];
@@ -169,7 +168,10 @@ describe("GET /api/meta/capabilities — drift guards", () => {
     const res = await call();
     const body = (await res.json()) as CapabilitiesBody;
     expect(body.data.fhir.restBaseUrl).toBe("/api/fhir");
-    expect(body.data.fhir.readScope).toBe(FHIR_READ_SCOPE);
+    // The face checks `fhir:read`, but nothing mints a token carrying it, so
+    // advertising it as an obtainable credential would be a claim the code
+    // cannot support.
+    expect(body.data.fhir.scopeMintable).toBe(false);
     expect(body.data.fhir.resourceTypes).toEqual([...FHIR_REST_RESOURCE_TYPES]);
     expect(body.data.fhir.operations).toEqual([FHIR_EVERYTHING_OPERATION]);
     expect(body.data.fhir.searchParams).toEqual([...FHIR_SEARCH_PARAMS]);

src/app/api/meta/capabilities/route.ts

@@ -41,7 +41,6 @@ import {
   GERMAN_ATC_DEFAULT_LOCALES,
 } from "@/lib/fhir/build-bundle";
 import {
-  FHIR_READ_SCOPE,
   FHIR_REST_RESOURCE_TYPES,
   FHIR_EVERYTHING_OPERATION,
   FHIR_SEARCH_PARAMS,
@@ -111,7 +110,13 @@ export const GET = apiHandler(async () => {
       // whole-record operation, the honoured search params and the narrow
       // Bearer scope. All sourced from the canonical `rest.ts` constants.
       restBaseUrl: "/api/fhir",
-      readScope: FHIR_READ_SCOPE,
+      // The face checks a narrow `fhir:read` scope, and NO code path mints a
+      // token carrying it — every mint grants a wildcard, the medication
+      // ingest scope, or an MCP scope. So the face is reachable by the owner's
+      // cookie session or a wildcard device token, and by nothing else. It is
+      // reported that way rather than advertising a credential a client cannot
+      // obtain.
+      scopeMintable: false,
       resourceTypes: FHIR_REST_RESOURCE_TYPES,
       operations: [FHIR_EVERYTHING_OPERATION],
       searchParams: FHIR_SEARCH_PARAMS,