fix(python): resolve ClassName() calls to __init__

internal/cbm/lsp/py_lsp.c

@@ -3249,7 +3249,28 @@ static void py_emit_call_for(PyLSPContext *ctx, TSNode call_node) {
                     py_emit_resolved_call_reason(ctx, qn, "lsp_import_alias", 0.85f, fname,
                                                  call_node);
                 } else if (qn && cbm_registry_lookup_type(ctx->registry, qn)) {
-                    py_emit_resolved_call(ctx, qn, "lsp_constructor", 0.85f, call_node);
+                    /* ClassName() binds to the __init__ the class declares
+                     * itself. An inherited __init__ is not followed: B(A)
+                     * without its own __init__ keeps the call on B, so a base
+                     * constructor does not collect every subclass
+                     * construction as its caller. Retarget only when this
+                     * binding IS the class being called. An instance
+                     * (`f = Foo(); f()`) keeps the class row: that call
+                     * dispatches to __call__, and a reason-join would invent
+                     * a Foo.__init__ edge. A builtins.* __init__ is not a
+                     * project constructor, so the class target stays. */
+                    const CBMRegisteredFunc *fi = NULL;
+                    if (qn_short && strcmp(qn_short, fname) == 0) {
+                        fi = cbm_registry_lookup_method(ctx->registry, qn, "__init__");
+                    }
+                    if (fi && fi->qualified_name &&
+                        strncmp(fi->qualified_name, "builtins.", sizeof("builtins.") - 1) != 0) {
+                        py_emit_resolved_call_reason(ctx, fi->qualified_name,
+                                                     "lsp_constructor_init", 0.85f, fname,
+                                                     call_node);
+                    } else {
+                        py_emit_resolved_call(ctx, qn, "lsp_constructor", 0.85f, call_node);
+                    }
                 }
             }
             return;

src/pipeline/lsp_resolve.h

@@ -388,6 +388,7 @@ static inline bool cbm_pipeline_invocation_reason_join_strategy(const char *stra
             strcmp(strategy, "lsp_method_ref_ctor_synth") == 0 ||
             strcmp(strategy, "lsp_dict_dispatch") == 0 ||
             strcmp(strategy, "lsp_import_alias") == 0 ||
+            strcmp(strategy, "lsp_constructor_init") == 0 ||
             strcmp(strategy, "php_method_dynamic") == 0);
 }
 

tests/repro/repro_lsp_go_py.c

@@ -64,8 +64,12 @@
  * PYTHON STRATEGY INVENTORY — every literal "lsp_..." emitted by py_lsp.c
  *   (grep '"lsp_' internal/cbm/lsp/py_lsp.c), with its keying site:
  *     lsp_direct                (py_lsp.c:1631)  module-local f()
- *     lsp_constructor           (py_lsp.c:1624)  ClassName() where the name is a
- *                                                NAMED type in scope
+ *     lsp_constructor           ClassName() where the class declares no __init__
+ *                               of its own (an inherited one is not followed)
+ *                               → the Class
+ *     lsp_constructor_init      ClassName() where the class declares its own
+ *                               __init__ → that __init__. The textual callee
+ *                               leaf stays the class name; reason joins it.
  *     lsp_method                (py_lsp.c:1731)  obj.method() on a NAMED-typed
  *                                                receiver (covers self.other())
  *     lsp_super                 (py_lsp.c:1693)  super().method() resolved on a
@@ -340,13 +344,24 @@ static const char kPyDirect[] =
     "def caller(v):\n"
     "    return helper(v)\n";
 
-/* lsp_constructor — ClassName() where the name is a NAMED type in scope
- * (py_lsp.c:1620-1624: cbm_scope_lookup yields a NAMED type → emit constructor
- * edge to the class QN). */
+/* lsp_constructor — ClassName() where the class has no user __init__.
+ * The edge stays on the Class node. A class that defines __init__ is
+ * lsp_constructor_init below; strstr would otherwise treat that strategy
+ * as a hit for "lsp_constructor". */
 static const char kPyConstructor[] =
+    "class Widget:\n"
+    "    def label(self):\n"
+    "        return 1\n"
+    "def caller():\n"
+    "    return Widget()\n";
+
+/* lsp_constructor_init — ClassName() resolves to the user __init__
+ * (issue #1642). reason carries the class-name leaf so the pipeline join
+ * still matches the textual call. */
+static const char kPyConstructorInit[] =
     "class Widget:\n"
     "    def __init__(self):\n"
-    "        pass\n"
+    "        self.ready = True\n"
     "def caller():\n"
     "    return Widget()\n";
 
@@ -538,6 +553,10 @@ TEST(repro_lsp_py_constructor) {
     return assert_lsp_strategy("main.py", kPyConstructor, "lsp_constructor");
 }
 
+TEST(repro_lsp_py_constructor_init) {
+    return assert_lsp_strategy("main.py", kPyConstructorInit, "lsp_constructor_init");
+}
+
 TEST(repro_lsp_py_method) {
     return assert_lsp_strategy("main.py", kPyMethod, "lsp_method");
 }
@@ -623,6 +642,7 @@ SUITE(repro_lsp_go_py) {
 
     RUN_TEST(repro_lsp_py_direct);
     RUN_TEST(repro_lsp_py_constructor);
+    RUN_TEST(repro_lsp_py_constructor_init);
     RUN_TEST(repro_lsp_py_method);
     RUN_TEST(repro_lsp_py_super);
     RUN_TEST(repro_lsp_py_super_init);

tests/test_edge_structural.c

@@ -826,14 +826,31 @@ TEST(es_decorates_attribute_csharp) {
  * resolves in the registry.  pass_usages.c handles this.
  * ══════════════════════════════════════════════════════════════════ */
 
-/* Python constructor syntax is a CALLS edge to the materialized Class node. */
+/* Python ClassName() with a user __init__ is a CALLS edge to that method.
+ * The Class node no longer receives the instantiation edge. A class with no
+ * user __init__ still targets the Class (lsp_constructor). */
 TEST(es_usage_crossfile_python) {
     static const ES_LangFile f[] = {
         {"models.py",
          "class User:\n    def __init__(self, name):\n        self.name = name\n"},
         {"main.py",
          "from .models import User\n\n\ndef create_user(name):\n    return User(name)\n"}};
-    ASSERT_EQ(es_exact_edge_by_name(f, 2, "CALLS", "create_user", "User"), 1);
+    ASSERT_EQ(es_exact_edge_by_name(f, 2, "CALLS", "create_user", "__init__"), 1);
+    ASSERT_EQ(es_exact_edge_by_name(f, 2, "CALLS", "create_user", "User"), 0);
+    PASS();
+}
+
+/* Issue #1642 repro: build() -> Embedder.__init__, not the Embedder class. */
+TEST(es_calls_python_constructor_init) {
+    static const ES_LangFile f[] = {
+        {"main.py", "class Embedder:\n"
+                    "    def __init__(self, model=\"x\"):\n"
+                    "        self.model = model\n"
+                    "\n"
+                    "def build():\n"
+                    "    return Embedder(model=\"y\")\n"}};
+    ASSERT_EQ(es_exact_edge_by_name(f, 1, "CALLS", "build", "__init__"), 1);
+    ASSERT_EQ(es_exact_edge_by_name(f, 1, "CALLS", "build", "Embedder"), 0);
     PASS();
 }
 
@@ -982,6 +999,7 @@ SUITE(edge_structural) {
     /* ── FAMILY 7: USAGE cross-file ─────────────────────────── */
     /* Uncertain: depends on USAGE extraction for each language. */
     RUN_TEST(es_usage_crossfile_python);
+    RUN_TEST(es_calls_python_constructor_init);
     RUN_TEST(es_usage_crossfile_typescript);
     RUN_TEST(es_usage_crossfile_go);
 

tests/test_lsp_resolution_probe.c

@@ -1837,16 +1837,62 @@ TEST(lrp_tsx_usage_import_type_with_decoy) {
     PASS();
 }
 
-/* Python: constructor syntax is an exact call to the materialized Class node. */
+/* Python: ClassName() with a user __init__ is an exact CALLS edge to that
+ * method. The Class node no longer receives the instantiation edge. */
 TEST(lrp_python_usage_instantiation) {
     static const LRP_File f[] = {
         {"model.py", "class User:\n    def __init__(self, name):\n        self.name = name\n"},
         {"main.py", "from .model import User\n\n\ndef create(name):\n    return User(name)\n"}};
     LRP_Proj lp;
     cbm_store_t *store = lrp_index(&lp, f, 2);
-    int exact = store ? lrp_exact_calls_by_name(store, lp.project, "create", "User") : -1;
+    int exact = store ? lrp_exact_calls_by_name(store, lp.project, "create", "__init__") : -1;
+    int class_edge = store ? lrp_exact_calls_by_name(store, lp.project, "create", "User") : -1;
     lrp_cleanup(&lp, store);
     ASSERT_EQ(exact, 1);
+    ASSERT_EQ(class_edge, 0);
+    PASS();
+}
+
+/* Python same-file subclasses in the graph: ClassName() binds only to an
+ * __init__ the class declares itself. B(A) declares none, so make_b keeps
+ * its CALLS edge on the class B and the inherited A.__init__ gets none.
+ * C(A) declares its own __init__, so make_c calls C.__init__, not C and not
+ * the inherited A.__init__. */
+TEST(lrp_python_subclass_constructor_own_init_only) {
+    static const LRP_File f[] = {{"main.py", "class A:\n"
+                                             "    def __init__(self):\n"
+                                             "        self.ready = True\n"
+                                             "\n"
+                                             "class B(A):\n"
+                                             "    def go(self):\n"
+                                             "        return 1\n"
+                                             "\n"
+                                             "class C(A):\n"
+                                             "    def __init__(self):\n"
+                                             "        self.ready = False\n"
+                                             "\n"
+                                             "def make_b():\n"
+                                             "    return B()\n"
+                                             "\n"
+                                             "def make_c():\n"
+                                             "    return C()\n"}};
+    LRP_Proj lp;
+    cbm_store_t *store = lrp_index(&lp, f, 1);
+    const char *p = store ? lp.project : NULL;
+    int b_class = lrp_exact_edge_by_qn_suffix(store, p, "CALLS", "main.make_b", "main.B");
+    int b_base_init =
+        lrp_exact_edge_by_qn_suffix(store, p, "CALLS", "main.make_b", "main.A.__init__");
+    int c_own_init =
+        lrp_exact_edge_by_qn_suffix(store, p, "CALLS", "main.make_c", "main.C.__init__");
+    int c_class = lrp_exact_edge_by_qn_suffix(store, p, "CALLS", "main.make_c", "main.C");
+    int c_base_init =
+        lrp_exact_edge_by_qn_suffix(store, p, "CALLS", "main.make_c", "main.A.__init__");
+    lrp_cleanup(&lp, store);
+    ASSERT_EQ(b_class, 1);
+    ASSERT_EQ(b_base_init, 0);
+    ASSERT_EQ(c_own_init, 1);
+    ASSERT_EQ(c_class, 0);
+    ASSERT_EQ(c_base_init, 0);
     PASS();
 }
 
@@ -1967,4 +2013,5 @@ SUITE(lsp_resolution_probe) {
     RUN_TEST(lrp_ts_usage_import_type_with_decoy);
     RUN_TEST(lrp_tsx_usage_import_type_with_decoy);
     RUN_TEST(lrp_python_usage_instantiation);
+    RUN_TEST(lrp_python_subclass_constructor_own_init_only);
 }

tests/test_pipeline.c

@@ -21140,8 +21140,9 @@ static int pyn_run_init_collision(int fillers) {
             const char *project = cbm_pipeline_project_name(p);
             imports[run] = pyn_edge(s, project, "tests.test_app.py.__file__",
                                     "src.rowpkg.layout.Layout", "IMPORTS");
+            /* Layout defines __init__, so Layout("demo") targets it (#1642). */
             calls[run] = pyn_edge(s, project, "tests.test_app.test_build",
-                                  "src.rowpkg.layout.Layout", "CALLS");
+                                  "src.rowpkg.layout.Layout.__init__", "CALLS");
             method[run] = pyn_edge(s, project, "tests.test_app.test_build",
                                    "src.rowpkg.layout.Layout.create", "CALLS");
             cbm_store_close(s);
@@ -21160,7 +21161,7 @@ static int pyn_run_init_collision(int fillers) {
     for (int run = 0; run < 2; run++) {
         ASSERT_EQ(rc[run], 0);
         ASSERT_TRUE(imports[run]); /* the class stays importable */
-        ASSERT_TRUE(calls[run]);   /* Layout("demo") */
+        ASSERT_TRUE(calls[run]);   /* Layout("demo") -> Layout.__init__ */
         ASSERT_TRUE(method[run]);  /* .create() through the constructed type */
     }
     PASS();