A demo wallet keeps working: pick one of my own profiles, and say it is arbitrary

Resolving "my profile" by ownership left one case refusing: several profile
documents are mine and none was created by this session, which is exactly a
reloaded wallet carrying the fixture seed. Sign-up then rejected — in the very
flow being built.

The first by document reference is now used, stable across reloads and openly
arbitrary. While the profile is not a built feature, "which of my fixtures am
I" has no true answer and does not need one.

This is not the impersonation that was removed. That one reached for a profile
by NAME and could land on a document belonging to somebody else; every candidate
here is a document I own. The invariant that matters holds: the app never
presents another person's profile as mine.

Downgraded to a warning, and reworded: the log now says the name shown as yours
is demo data rather than announcing a refusal that no longer happens.

src/shared/context/FestipodDataContext.tsx

@@ -610,7 +610,19 @@ function useNgData(): FestipodDataContextValue {
     if (myProfileDocId) return users.find(u => u.id === myProfileDocId);
     if (myOwnedProfiles === null) return undefined;       // not answered yet
     if (myOwnedProfiles.length === 1) return myOwnedProfiles[0];
-    return undefined;                                     // none, or ambiguous
+    if (myOwnedProfiles.length === 0) return undefined;   // none — one gets created
+    // SEVERAL profile documents are mine, and none was created by this session:
+    // the fixture seed writes its profiles into my own protected scope, so a
+    // reloaded demo wallet lands here. Pick the first by document reference —
+    // stable across reloads, and arbitrary, which is honest: while the profile
+    // is not a built feature, "which of my fixtures am I" has no true answer.
+    //
+    // This is NOT the impersonation that was removed. That one reached for a
+    // profile by NAME and could land on a document belonging to somebody else.
+    // Every candidate here is a document I own, so the invariant that holds is
+    // the one that matters: the app never presents another person's profile as
+    // mine. Delete this branch the day a profile is really created and known.
+    return [...myOwnedProfiles].sort((a, b) => a.id.localeCompare(b.id))[0];
   }, [users, myProfileDocId, myOwnedProfiles]);
   const currentUserId = currentUser?.id || '';
   // Identity-first log prefix, reused by every DATA log below (including the
@@ -716,22 +728,23 @@ function useNgData(): FestipodDataContextValue {
     });
   }, [ready, userQuery.isSuccess, myOwnedProfiles]);
 
-  // --- MY PROFILE: say it when the answer is ambiguous ------------------------
+  // --- MY PROFILE: say it when the answer is arbitrary ------------------------
   // Several profile documents are mine and none was created by this session (the
-  // opt-in fixture seed writes its profiles into my own protected scope). There
-  // is no honest way to tell which one is the person at the keyboard, so nothing
-  // is picked — `currentUser` stays undefined and the mutations that need it
-  // refuse. Silence here would look exactly like "the read has not landed".
+  // opt-in fixture seed writes its profiles into my own protected scope). One is
+  // picked deterministically so the app stays usable on a demo wallet, but the
+  // pick carries no meaning — say so once, or a fixture person silently becomes
+  // "you" and nobody wonders why.
   const warnedAmbiguousProfile = useRef(false);
   useEffect(() => {
     if (myProfileDocId) return;
     if (myOwnedProfiles === null || myOwnedProfiles.length <= 1) return;
     if (warnedAmbiguousProfile.current) return;
     warnedAmbiguousProfile.current = true;
-    console.error(
+    console.warn(
       `${logPrefix} ${myOwnedProfiles.length} profile documents are mine and none was created by ` +
-        `this session — which one is me cannot be told apart, so NO profile is resolved (a fixture ` +
-        `seed run on this wallet is the usual cause). Sign-up and profile edition will refuse.`,
+        `this session (a fixture seed run on this wallet is the usual cause). The first by document ` +
+        `reference is used as mine — a stable but ARBITRARY pick, so the name shown as yours is ` +
+        `demo data, not you.`,
     );
   }, [myOwnedProfiles, myProfileDocId]);