revert sentry__ensure_user_id; don't mutate caller-provided user

The helper mutated its user argument, which leaked out through
sentry_set_user (caller's value) and sentry__session_sync_user
(scope->user). Revert the helper and inline both sites again.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jpnurmi

src/sentry_core.c

@@ -856,17 +856,6 @@ sentry__ensure_event_id(sentry_value_t event, sentry_uuid_t *uuid_out)
     return event_id;
 }
 
-sentry_value_t
-sentry__ensure_user_id(sentry_value_t user, const char *installation_id)
-{
-    sentry_value_t user_id = sentry_value_get_by_key(user, "id");
-    if (sentry_value_is_null(user_id) && installation_id) {
-        user_id = sentry_value_new_string(installation_id);
-        sentry_value_set_by_key(user, "id", user_id);
-    }
-    return user_id;
-}
-
 void
 sentry_set_user(sentry_value_t user)
 {

src/sentry_core.h

@@ -109,14 +109,6 @@ sentry_uuid_t sentry__new_event_id(void);
 sentry_value_t sentry__ensure_event_id(
     sentry_value_t event, sentry_uuid_t *uuid_out);
 
-/**
- * This will ensure that the given `user` has an `id`, falling back to
- * `installation_id` when the user has no explicit id. Returns the id value
- * (existing or newly-set), or a null value if neither is available.
- */
-sentry_value_t sentry__ensure_user_id(
-    sentry_value_t user, const char *installation_id);
-
 /**
  * This will return an owned reference to the global options.
  */

src/sentry_scope.c

@@ -360,9 +360,12 @@ sentry__scope_apply_to_event(const sentry_scope_t *scope,
             if (IS_NULL("user")) {
                 SET("user", sentry__value_clone(scope->user));
             }
+            // patch missing user ID with installation ID
             sentry_value_t user = sentry_value_get_by_key(event, "user");
-            if (sentry_value_get_type(user) == SENTRY_VALUE_TYPE_OBJECT) {
-                sentry__ensure_user_id(user, options->run->installation_id);
+            if (sentry_value_get_type(user) == SENTRY_VALUE_TYPE_OBJECT
+                && sentry_value_is_null(sentry_value_get_by_key(user, "id"))) {
+                sentry_value_set_by_key(user, "id",
+                    sentry_value_new_string(options->run->installation_id));
             }
         } else if (sentry_value_get_length(scope->user) > 0) {
             PLACE_VALUE("user", scope->user);

src/sentry_session.c

@@ -302,8 +302,12 @@ void
 sentry__session_sync_user(
     sentry_session_t *session, sentry_value_t user, const char *installation_id)
 {
-    sentry_value_t did = sentry__ensure_user_id(user, installation_id);
+    sentry_value_t did = sentry_value_get_by_key(user, "id");
     sentry_value_decref(session->distinct_id);
-    sentry_value_incref(did);
-    session->distinct_id = did;
+    if (sentry_value_is_null(did) && installation_id) {
+        session->distinct_id = sentry_value_new_string(installation_id);
+    } else {
+        sentry_value_incref(did);
+        session->distinct_id = did;
+    }
 }