fix(pm): inherit declared index namespaces exactly

Author: speak-agent

src/pm/index_route.cppm

@@ -159,9 +159,16 @@ Lookup lookup_descriptor(const IndexRoute& route,
         // BareDefault=false` matches prepare's disambiguation: a descriptor
         // with no namespace is reached through the explicit `(∅, name)` rung
         // below, not by being waved through on the default-namespace rung.
+        // A descriptor served by one declared project index inherits that
+        // index's namespace when it omits package.namespace.  Pass the owning
+        // index explicitly; leaving this empty turns valid name-only local
+        // descriptors into false misses (including [indices] default).
+        const auto* owner = route.find_for_ns(candidate.namespace_);
+        const std::string_view ownerNs = owner
+            ? std::string_view{owner->name} : std::string_view{};
         if (!mcpp::manifest::xpkg_lua_identity_matches(
                 *lua, candidate.namespace_, candidate.shortName,
-                /*allowLegacyBareDefault=*/false)) {
+                /*allowLegacyBareDefault=*/false, ownerNs)) {
             continue;
         }
         auto declaredNs = mcpp::manifest::extract_xpkg_namespace(*lua);

tests/unit/test_pm_index_route.cpp

@@ -82,6 +82,26 @@ TEST(PmIndexRoute, DottedSelectorResolvesThroughItsExactCoordinate) {
     EXPECT_EQ(found.hit->coord.shortName, "util");
 }
 
+TEST(PmIndexRoute, NameOnlyDescriptorInheritsOwningLocalIndexNamespace) {
+    LocalIndex idx("name-only");
+    std::ofstream(idx.root / "pkgs" / "a" / "acme.util.lua") << R"(
+package = {
+    spec = "1",
+    name = "util",
+    type = "package",
+}
+)";
+    auto indices = local_map(idx);
+    mcpp::pm::IndexRoute route{ &indices, "/nowhere", nullptr };
+
+    auto selector = mcpp::pm::resolve_dependency_selector("acme.util");
+    auto found = mcpp::pm::lookup_descriptor(route, selector.candidates);
+
+    ASSERT_TRUE(found.hit.has_value());
+    EXPECT_EQ(found.hit->coord.namespace_, "acme");
+    EXPECT_EQ(found.hit->coord.shortName, "util");
+}
+
 TEST(PmIndexRoute, LiteralDottedShortNameNeverMatches) {
     LocalIndex idx("literal");
     auto indices = local_map(idx);