diff --git a/graphify/extract.py b/graphify/extract.py
index 7cc9e62c90..2c7f14f049 100644
--- a/graphify/extract.py
+++ b/graphify/extract.py
@@ -103,6 +103,7 @@
     _load_workspace_packages,
     _match_tsconfig_alias,
     _merge_decl_def_classes,
+    _merge_go_package_types,
     _node_disambiguation_source_key,
     _package_entry_candidates,
     _parse_js_tree,
@@ -6466,6 +6467,10 @@ def _describe_syntax_error(rel: str, line: "int | None", kept: int) -> str:
     # also means disambiguation sees one source_file per id and won't split them.
     _merge_decl_def_classes(all_nodes, all_edges)
 
+    # Same fold for a Go package's type, which every file declaring a method on it mints
+    # again under one id; also before disambiguation, which would otherwise split them.
+    _merge_go_package_types(all_nodes, all_edges)
+
     # Remap file node IDs from absolute-path-derived to the canonical
     # {parent_dir}_{stem} spec form so (a) graph.json edge endpoints are stable
     # across machines (#502) and (b) AST file nodes match the IDs semantic
diff --git a/graphify/extractors/resolution.py b/graphify/extractors/resolution.py
index ed9e857e87..a1cb4fedb8 100644
--- a/graphify/extractors/resolution.py
+++ b/graphify/extractors/resolution.py
@@ -2432,6 +2432,79 @@ def _merge_decl_def_classes(
         rewritten.append(e)
     all_edges[:] = rewritten
 
+def _merge_go_package_types(
+    all_nodes: list[dict],
+    all_edges: list[dict],
+) -> None:
+    """Merge a Go package's type declared in one file with the copies minted by the
+    other files that declare methods on it into ONE node (#3399).
+
+    ``extract_go`` keys a type on its package directory, so ``type Server`` in ``a.go``
+    and ``func (s *Server) Close()`` in ``b.go`` mint the SAME id twice, differing only
+    in ``source_file``. Left alone, ``_disambiguate_colliding_node_ids`` splits them
+    apart by path, fragmenting one type into several partial nodes that each own some of
+    its methods — the declaring file's node owning none of them — which every
+    single-definition god-node guard downstream then reads as an ambiguity and bails on.
+    This is the Go analogue of ``_merge_decl_def_classes`` and runs at the same point,
+    before disambiguation.
+
+    GOD-NODE GUARDS:
+
+      * Every node in the id-collision must be a ``.go`` file in ONE directory — Go's
+        package unit. The id folds in only the directory's NAME, so ``a/svc`` and
+        ``b/svc`` collide on id while being different packages; those stay split.
+      * Folding stops at a ``_test.go`` member, whose package clause may be the separate
+        ``svc_test`` package declaring a type of its own name. The clause is not parsed,
+        so same-directory is not evidence of same package there.
+
+    No edge re-pointing is needed: the group already shares one id, so every edge
+    already points at the survivor. The declaration site wins — the file holding
+    ``type X``, the only one with a ``contains`` edge to it — and the dropped nodes'
+    methods keep their own ``source_file``, so no location is lost with them.
+    """
+    by_id: dict[str, list[dict]] = {}
+    for n in all_nodes:
+        nid = n.get("id")
+        label = str(n.get("label", ""))
+        if not isinstance(nid, str) or not nid or n.get("file_type") != "code":
+            continue
+        # A Go type name holds neither character, while every other label the extractor
+        # mints does: `Run()`, `.Close()`, and the file node's own `a.go`.
+        if not label or "." in label or "(" in label:
+            continue
+        if Path(str(n.get("source_file", ""))).suffix.lower() != ".go":
+            continue
+        by_id.setdefault(nid, []).append(n)
+
+    declaring_files: dict[str, set[str]] = {}
+    for e in all_edges:
+        if e.get("relation") == "contains":
+            declaring_files.setdefault(str(e.get("target", "")), set()).add(
+                str(e.get("source_file", "")))
+
+    drop_objs: set[int] = set()
+    for nid, group in by_id.items():
+        if len(group) < 2:
+            continue
+        files = [Path(str(n.get("source_file", ""))) for n in group]
+        if len({f.parent for f in files}) != 1:
+            continue
+        if any(f.name.endswith("_test.go") for f in files):
+            continue
+        # A type whose declaring file is outside the corpus leaves the whole group
+        # method-only; one node is still the answer, so fold on the lowest path.
+        declared = declaring_files.get(nid, set())
+        candidates = [n for n in group if str(n.get("source_file", "")) in declared] or group
+        keeper = min(candidates, key=lambda n: (str(n.get("source_file", "")),
+                                                str(n.get("source_location", ""))))
+        for node in group:
+            if node is not keeper:
+                drop_objs.add(id(node))
+
+    if drop_objs:
+        all_nodes[:] = [n for n in all_nodes if id(n) not in drop_objs]
+
+
 def _resolve_cross_file_java_imports(
     per_file: list[dict],
     paths: list[Path],
diff --git a/tests/test_go_package_type_fold.py b/tests/test_go_package_type_fold.py
new file mode 100644
index 0000000000..0a93886cee
--- /dev/null
+++ b/tests/test_go_package_type_fold.py
@@ -0,0 +1,106 @@
+"""A Go package's type is one node even when its methods are spread across files.
+
+``extract_go`` keys a type on its package directory, so every file declaring a method on
+it mints the type again under the same id, and disambiguation then split those apart by
+path — leaving one type fragmented into several partial nodes, each owning some of its
+methods, which every single-definition guard downstream reads as an ambiguity. The fold
+runs before disambiguation; the negative cases pin what must stay split, since the id
+folds in the directory's name rather than its path and the package clause is not parsed.
+"""
+from __future__ import annotations
+
+import importlib
+from pathlib import Path
+
+import pytest
+
+from graphify.extract import extract
+
+pytestmark = pytest.mark.skipif(
+    importlib.util.find_spec("tree_sitter_go") is None,
+    reason="tree_sitter_go not installed",
+)
+
+
+def _extract(tmp_path, files: dict[str, str]):
+    for name, body in files.items():
+        path = tmp_path / name
+        path.parent.mkdir(parents=True, exist_ok=True)
+        path.write_text(body, encoding="utf-8")
+    return extract([tmp_path / n for n in files],
+                   cache_root=tmp_path / "graphify-out", parallel=False)
+
+
+def _nodes(result, label: str) -> list[dict]:
+    return [n for n in result["nodes"] if n["label"] == label]
+
+
+def _edges_from(result, node_id: str, relation: str) -> set[str]:
+    label = {n["id"]: n["label"] for n in result["nodes"]}
+    return {label.get(e["target"], e["target"]) for e in result["edges"]
+            if e["relation"] == relation and e["source"] == node_id}
+
+
+def test_a_type_whose_methods_live_in_other_files_owns_all_of_them(tmp_path):
+    result = _extract(tmp_path, {
+        "svc/a.go": ("package svc\n\ntype Server struct{}\n\n"
+                     "func Run(srv *Server) { srv.Close() }\n"),
+        "svc/b.go": "package svc\n\nfunc (s *Server) Close() {}\n",
+        "svc/c.go": "package svc\n\nfunc (s *Server) Save() {}\n",
+    })
+    servers = _nodes(result, "Server")
+    assert len(servers) == 1, [n["id"] for n in servers]
+    assert Path(str(servers[0]["source_file"])).name == "a.go"
+    assert _edges_from(result, servers[0]["id"], "method") == {".Close()", ".Save()"}
+
+
+def test_a_reference_to_the_type_reaches_the_node_that_owns_the_methods(tmp_path):
+    result = _extract(tmp_path, {
+        "svc/a.go": "package svc\n\ntype Server struct{}\n",
+        "svc/b.go": "package svc\n\nfunc (s *Server) Close() {}\n",
+        "svc/c.go": "package svc\n\nfunc Run(srv *Server) {}\n",
+    })
+    servers = _nodes(result, "Server")
+    assert len(servers) == 1, [n["id"] for n in servers]
+    refs = [e for e in result["edges"]
+            if e["relation"] == "references" and e["target"] == servers[0]["id"]]
+    assert refs, "the parameter type must reference the one Server node"
+    assert _edges_from(result, servers[0]["id"], "method") == {".Close()"}
+
+
+def test_the_declaring_file_survives_a_lower_sorting_method_file(tmp_path):
+    result = _extract(tmp_path, {
+        "svc/a.go": "package svc\n\nfunc (s *Server) Close() {}\n",
+        "svc/z.go": "package svc\n\ntype Server struct{}\n",
+    })
+    servers = _nodes(result, "Server")
+    assert len(servers) == 1, [n["id"] for n in servers]
+    assert Path(str(servers[0]["source_file"])).name == "z.go"
+
+
+def test_two_packages_sharing_a_directory_name_stay_split(tmp_path):
+    result = _extract(tmp_path, {
+        "a/svc/x.go": "package svc\n\ntype Server struct{}\n\nfunc (s *Server) Save() {}\n",
+        "b/svc/y.go": "package svc\n\nfunc (s *Server) Close() {}\n",
+    })
+    assert len(_nodes(result, "Server")) == 2
+
+
+def test_an_external_test_package_in_the_same_directory_stays_split(tmp_path):
+    result = _extract(tmp_path, {
+        "svc/a.go": "package svc\n\ntype Fixture struct{}\n\nfunc (f *Fixture) Save() {}\n",
+        "svc/a_test.go": ("package svc_test\n\ntype Fixture struct{}\n\n"
+                          "func (f *Fixture) Reset() {}\n"),
+    })
+    assert len(_nodes(result, "Fixture")) == 2
+
+
+def test_a_function_and_a_method_of_the_same_name_are_untouched(tmp_path):
+    # The fold only ever considers bare type labels, so a package whose helper and method
+    # share a name keeps both nodes.
+    result = _extract(tmp_path, {
+        "svc/a.go": "package svc\n\ntype Server struct{}\n\nfunc Close() {}\n",
+        "svc/b.go": "package svc\n\nfunc (s *Server) Close() {}\n",
+    })
+    assert len(_nodes(result, "Close()")) == 1
+    assert len(_nodes(result, ".Close()")) == 1