fix(jvm): resolve mixed Java/Kotlin callgraph edges via declared packages

internal/cbm/lsp/go_lsp.h

@@ -86,6 +86,7 @@ typedef struct {
     const char* method_names_str; // "|"-separated method names for interfaces (e.g. "Get|Put|Delete")
     bool is_interface;
     CBMLanguage lang;           // language of the file that defined this — used by Tier 2 per-language registry build to filter all_defs
+    const char* namespace_name; // declared namespace/package for source-root-independent JVM filtering
 } CBMLSPDef;
 
 // Parse source, build registry from defs + stdlib, run LSP.

internal/cbm/lsp/kotlin_lsp.c

@@ -4151,6 +4151,85 @@ void cbm_run_kotlin_lsp(CBMArena *arena, CBMFileResult *result, const char *sour
  * a call site in another file resolves to the right node. Types and functions
  * keep their full project-qualified QN; functions carry receiver_type so the
  * sole-definer fallback can tell a top-level fun from a method. */
+static const char *kt_cross_builtin_return_qn(const char *name) {
+    if (!name) {
+        return NULL;
+    }
+    if (strcmp(name, "String") == 0) {
+        return "kotlin.String";
+    }
+    if (strcmp(name, "Int") == 0 || strcmp(name, "Integer") == 0) {
+        return "kotlin.Int";
+    }
+    if (strcmp(name, "Long") == 0) {
+        return "kotlin.Long";
+    }
+    if (strcmp(name, "Float") == 0) {
+        return "kotlin.Float";
+    }
+    if (strcmp(name, "Double") == 0) {
+        return "kotlin.Double";
+    }
+    if (strcmp(name, "Boolean") == 0 || strcmp(name, "Bool") == 0) {
+        return "kotlin.Boolean";
+    }
+    if (strcmp(name, "Char") == 0 || strcmp(name, "Character") == 0) {
+        return "kotlin.Char";
+    }
+    if (strcmp(name, "Byte") == 0) {
+        return "kotlin.Byte";
+    }
+    if (strcmp(name, "Short") == 0) {
+        return "kotlin.Short";
+    }
+    if (strcmp(name, "Unit") == 0 || strcmp(name, "Void") == 0 || strcmp(name, "void") == 0) {
+        return "kotlin.Unit";
+    }
+    if (strcmp(name, "Any") == 0 || strcmp(name, "Object") == 0) {
+        return "kotlin.Any";
+    }
+    return NULL;
+}
+
+static const CBMType *kt_cross_return_type(CBMArena *arena, const CBMLSPDef *d) {
+    if (!arena || !d || !d->return_types || !d->return_types[0]) {
+        return NULL;
+    }
+    const char *text = d->return_types;
+    const char *bar = strchr(text, '|');
+    const char *first = bar ? cbm_arena_strndup(arena, text, (size_t)(bar - text)) : text;
+    if (!first || !first[0]) {
+        return NULL;
+    }
+    if (!strchr(first, '.')) {
+        const char *builtin = kt_cross_builtin_return_qn(first);
+        if (builtin) {
+            first = builtin;
+        } else if (d->namespace_name && d->namespace_name[0]) {
+            first = kt_join_dot(arena, d->namespace_name, first);
+        }
+    }
+    return cbm_type_named(arena, first);
+}
+
+static const CBMType *kt_cross_func_sig_with_return(CBMArena *arena, const CBMLSPDef *d) {
+    const CBMType *ret = kt_cross_return_type(arena, d);
+    if (!ret || cbm_type_is_unknown(ret)) {
+        return NULL;
+    }
+    const char **empty_pn = (const char **)cbm_arena_alloc(arena, sizeof(*empty_pn));
+    const CBMType **empty_pt = (const CBMType **)cbm_arena_alloc(arena, sizeof(*empty_pt));
+    const CBMType **rets = (const CBMType **)cbm_arena_alloc(arena, 2 * sizeof(*rets));
+    if (!empty_pn || !empty_pt || !rets) {
+        return NULL;
+    }
+    empty_pn[0] = NULL;
+    empty_pt[0] = NULL;
+    rets[0] = ret;
+    rets[1] = NULL;
+    return cbm_type_func(arena, empty_pn, empty_pt, rets);
+}
+
 static void kt_register_cross_def(CBMTypeRegistry *reg, CBMArena *arena, const CBMLSPDef *d) {
     if (!d->qualified_name || !d->short_name || !d->label) {
         return;
@@ -4200,6 +4279,7 @@ static void kt_register_cross_def(CBMTypeRegistry *reg, CBMArena *arena, const C
         /* receiver_type distinguishes a top-level fun (NULL) from a method
          * (set) — the sole-definer fallback only matches top-level funs. */
         rf.receiver_type = d->receiver_type;
+        rf.signature = kt_cross_func_sig_with_return(arena, d);
         cbm_registry_add_func(reg, rf);
     }
 }

src/pipeline/lsp_resolve.h

@@ -64,25 +64,78 @@ static inline const char *cbm_lsp_bare_segment(const char *name) {
     return seg;
 }
 
+/* Tail helper: return the start of the final two dot-separated segments
+ * ("Class.method") or NULL when the QN is too short. */
+static inline const char *cbm_pipeline_qn_class_method_tail(const char *qn) {
+    if (!qn) {
+        return NULL;
+    }
+    const char *last = strrchr(qn, '.');
+    if (!last || last == qn) {
+        return NULL;
+    }
+    const char *second = last;
+    while (second > qn) {
+        second--;
+        if (*second == '.') {
+            if (second == qn) {
+                return qn;
+            }
+            return second + 1;
+        }
+    }
+    return qn;
+}
+
+static inline const char *cbm_pipeline_call_callee_leaf(const char *callee_name) {
+    return cbm_lsp_bare_segment(callee_name);
+}
+
+/* Gate for the unique-`Class.method`-tail fallbacks below. Tail-matching by
+ * leaf is safe where class-per-file package semantics hold — the JVM
+ * languages (Java/Kotlin): the declared `package` is ground truth, a class
+ * name is unique within a package, and mixed Gradle/Maven source roots
+ * (`src/main/java` + `src/main/kotlin`) legitimately produce path-derived
+ * module QNs that disagree with the package-shaped QNs the LSP emits, so
+ * the tail is the only reliable join key. In other languages the same-name
+ * guarantee does not exist (Python/TS re-export shims, Go internal clones,
+ * C++ template instantiations), and a single wrong-module coincidence
+ * would fabricate a CALLS edge — so the fallbacks stay off there. */
+static inline bool cbm_pipeline_lsp_allow_tail_match(CBMLanguage lang) {
+    return lang == CBM_LANG_JAVA || lang == CBM_LANG_KOTLIN;
+}
+
+static inline int cbm_pipeline_qn_class_method_tail_eq(const char *qn, const char *tail) {
+    const char *qt = cbm_pipeline_qn_class_method_tail(qn);
+    return qt && tail && strcmp(qt, tail) == 0;
+}
+
 /* Look up the highest-confidence LSP-resolved call entry whose caller QN
  * matches the textual call's enclosing function and whose callee QN
  * short-name matches the textual callee. Returns a pointer into `arr`
  * or NULL if no qualifying entry exists.
  *
- * Match rule: the LSP emits CBMResolvedCall entries whose caller_qn
- * matches the call's enclosing function and whose callee_qn ends with
- * the textual callee_name as the last dot-separated segment. The
- * pointer returned aliases into `arr` and stays valid as long as the
+ * Match rule:
+ *   1. exact caller_qn + callee short-name match wins first;
+ *   2. if no exact caller match exists AND allow_tail_match is set
+ *      (JVM callers only, see cbm_pipeline_lsp_allow_tail_match), a
+ *      unique Class.method tail match between rc->caller_qn and
+ *      call->enclosing_func_qn may win;
+ *   3. ambiguous tails return NULL so the registry fallback stays in
+ *      control.
+ *
+ * The pointer returned aliases into `arr` and stays valid as long as the
  * underlying CBMFileResult is alive. */
 static inline const CBMResolvedCall *cbm_pipeline_find_lsp_resolution(
-    const CBMResolvedCallArray *arr, const CBMCall *call) {
+    const CBMResolvedCallArray *arr, const CBMCall *call, bool allow_tail_match) {
     if (!arr || arr->count == 0 || !call) {
         return NULL;
     }
     if (!call->enclosing_func_qn || !call->callee_name) {
         return NULL;
     }
-    const CBMResolvedCall *best = NULL;
+
+    const CBMResolvedCall *best_exact = NULL;
     for (int i = 0; i < arr->count; i++) {
         const CBMResolvedCall *rc = &arr->items[i];
         if (!rc->caller_qn || !rc->callee_qn) {
@@ -124,53 +177,120 @@ static inline const CBMResolvedCall *cbm_pipeline_find_lsp_resolution(
                 continue;
             }
         }
-        if (!best || rc->confidence > best->confidence) {
-            best = rc;
+        if (!best_exact || rc->confidence > best_exact->confidence) {
+            best_exact = rc;
+        }
+    }
+    if (best_exact) {
+        return best_exact;
+    }
+    if (!allow_tail_match) {
+        return NULL;
+    }
+
+    const char *call_tail = cbm_pipeline_qn_class_method_tail(call->enclosing_func_qn);
+    if (!call_tail) {
+        return NULL;
+    }
+
+    const CBMResolvedCall *best_tail = NULL;
+    for (int i = 0; i < arr->count; i++) {
+        const CBMResolvedCall *rc = &arr->items[i];
+        if (!rc->caller_qn || !rc->callee_qn) {
+            continue;
+        }
+        if (rc->confidence < CBM_LSP_CONFIDENCE_FLOOR) {
+            continue;
         }
+        const char *short_name = strrchr(rc->callee_qn, '.');
+        short_name = short_name ? short_name + SKIP_ONE : rc->callee_qn;
+        const char *call_leaf = cbm_pipeline_call_callee_leaf(call->callee_name);
+        if (!call_leaf || strcmp(short_name, call_leaf) != 0) {
+            continue;
+        }
+        if (!cbm_pipeline_qn_class_method_tail_eq(rc->caller_qn, call_tail)) {
+            continue;
+        }
+        if (best_tail) {
+            return NULL;
+        }
+        best_tail = rc;
     }
-    return best;
+    return best_tail;
 }
 
 /* Resolve an LSP-emitted callee_qn to a graph-buffer node.
  *
- * Per-file LSPs (notably py_lsp) sometimes emit `callee_qn` as the raw
- * import-module path the source code uses (e.g. `greeter.Greeter` from
- * `from greeter import Greeter`) rather than the project-qualified QN
- * the gbuf actually stores (`<project>.greeter.Greeter`). This is
- * unavoidable at the per-file LSP layer: the LSP cannot tell in-project
- * imports (qualify) from external imports (don't qualify, e.g. `os.path`)
- * without consulting the gbuf, which is built downstream.
- *
- * The fallback rule: try the LSP-emitted QN as-is first; on miss, retry
- * with `<project>.<callee_qn>`. If that also misses, the target is
- * external/unknown and the caller drops the edge — same as today.
+ * Per-file LSPs sometimes emit `callee_qn` as the raw package-shaped
+ * import path the source code uses rather than the project-qualified QN
+ * the gbuf actually stores. The fallback rule is:
+ *   1. try the LSP-emitted QN as-is;
+ *   2. retry with `<project>.<callee_qn>` when needed;
+ *   3. if both fail AND allow_tail_match is set (JVM callers only, see
+ *      cbm_pipeline_lsp_allow_tail_match), use the exact node-name index
+ *      to narrow candidates by short method name and accept exactly one
+ *      Function/Method whose qualified_name has the same Class.method
+ *      tail.
  *
  * Returns the matching node, or NULL if neither lookup hits. */
 static inline const cbm_gbuf_node_t *cbm_pipeline_lsp_target_node(const cbm_gbuf_t *gbuf,
                                                                   const char *project_name,
-                                                                  const char *callee_qn) {
+                                                                  const char *callee_qn,
+                                                                  bool allow_tail_match) {
     if (!gbuf || !callee_qn) {
         return NULL;
     }
     const cbm_gbuf_node_t *direct = cbm_gbuf_find_by_qn(gbuf, callee_qn);
     if (direct) {
         return direct;
     }
-    if (!project_name || !project_name[0]) {
+    if (project_name && project_name[0]) {
+        size_t proj_len = strlen(project_name);
+        if (!(strncmp(callee_qn, project_name, proj_len) == 0 && callee_qn[proj_len] == '.')) {
+            char buf[CBM_SZ_1K];
+            int written = snprintf(buf, sizeof(buf), "%s.%s", project_name, callee_qn);
+            if (written > 0 && (size_t)written < sizeof(buf)) {
+                const cbm_gbuf_node_t *prefixed = cbm_gbuf_find_by_qn(gbuf, buf);
+                if (prefixed) {
+                    return prefixed;
+                }
+            }
+        }
+    }
+    if (!allow_tail_match) {
         return NULL;
     }
-    /* Skip the prefix retry if callee_qn is already project-qualified —
-     * avoids producing nonsense like `proj.proj.foo.Bar`. */
-    size_t proj_len = strlen(project_name);
-    if (strncmp(callee_qn, project_name, proj_len) == 0 && callee_qn[proj_len] == '.') {
+
+    const char *short_name = strrchr(callee_qn, '.');
+    short_name = short_name ? short_name + SKIP_ONE : callee_qn;
+    const char *callee_tail = cbm_pipeline_qn_class_method_tail(callee_qn);
+    if (!callee_tail) {
         return NULL;
     }
-    char buf[CBM_SZ_1K];
-    int written = snprintf(buf, sizeof(buf), "%s.%s", project_name, callee_qn);
-    if (written < 0 || (size_t)written >= sizeof(buf)) {
+    const cbm_gbuf_node_t **hits = NULL;
+    int hit_count = 0;
+    if (cbm_gbuf_find_by_name(gbuf, short_name, &hits, &hit_count) != 0 || hit_count == 0) {
         return NULL;
     }
-    return cbm_gbuf_find_by_qn(gbuf, buf);
+
+    const cbm_gbuf_node_t *match = NULL;
+    for (int i = 0; i < hit_count; i++) {
+        const cbm_gbuf_node_t *cand = hits[i];
+        if (!cand || !cand->label || !cand->qualified_name) {
+            continue;
+        }
+        if (strcmp(cand->label, "Function") != 0 && strcmp(cand->label, "Method") != 0) {
+            continue;
+        }
+        if (!cbm_pipeline_qn_class_method_tail_eq(cand->qualified_name, callee_tail)) {
+            continue;
+        }
+        if (match) {
+            return NULL;
+        }
+        match = cand;
+    }
+    return match;
 }
 
 #endif /* CBM_PIPELINE_LSP_RESOLVE_H */

src/pipeline/pass_calls.c

@@ -428,11 +428,13 @@ static int resolve_single_call(cbm_pipeline_ctx_t *ctx, CBMCall *call,
         return 0;
     }
 
-    /* LSP-resolved calls take precedence over registry-textual matching. */
-    const CBMResolvedCall *lsp = cbm_pipeline_find_lsp_resolution(lsp_calls, call);
+    /* LSP-resolved calls take precedence over registry-textual matching.
+     * Unique-tail fallbacks are JVM-only (see cbm_pipeline_lsp_allow_tail_match). */
+    bool allow_tail = cbm_pipeline_lsp_allow_tail_match(lang);
+    const CBMResolvedCall *lsp = cbm_pipeline_find_lsp_resolution(lsp_calls, call, allow_tail);
     if (lsp) {
         const cbm_gbuf_node_t *target_node =
-            cbm_pipeline_lsp_target_node(ctx->gbuf, ctx->project_name, lsp->callee_qn);
+            cbm_pipeline_lsp_target_node(ctx->gbuf, ctx->project_name, lsp->callee_qn, allow_tail);
         if (target_node && source_node->id != target_node->id) {
             cbm_resolution_t res = {0};
             /* Use the gbuf node's QN so downstream edge props show the canonical