diff --git a/graphify/extractors/csharp.py b/graphify/extractors/csharp.py
index f823d64c3..4519de8f2 100644
--- a/graphify/extractors/csharp.py
+++ b/graphify/extractors/csharp.py
@@ -164,6 +164,35 @@ def _metadata(value: object) -> dict:
     return value if isinstance(value, dict) else {}
 
 
+def _razor_imports_dir(source_file: object) -> str | None:
+    """The directory prefix an ``_Imports.razor``'s directives apply to.
+
+    Returns the file's parent directory with normalized separators ("" for the
+    corpus root), or None when the file is not an ``_Imports.razor``.
+    """
+    if not isinstance(source_file, str) or not source_file:
+        return None
+    norm = source_file.replace("\\", "/")
+    parts = norm.rstrip("/").rsplit("/", 1)
+    name = parts[-1]
+    if name.lower() != "_imports.razor":
+        return None
+    return parts[0] if len(parts) == 2 else ""
+
+
+def _razor_dir_applies(imports_dir: str, source_file: str) -> bool:
+    """True when an ``_Imports.razor`` in ``imports_dir`` governs ``source_file``.
+
+    The Razor compiler applies ``_Imports.razor`` directives to every Razor
+    file in the same directory and every subdirectory below it.
+    """
+    norm = source_file.replace("\\", "/")
+    file_dir = norm.rsplit("/", 1)[0] if "/" in norm else ""
+    if not imports_dir:
+        return True  # root _Imports.razor governs the whole tree
+    return file_dir == imports_dir or file_dir.startswith(imports_dir + "/")
+
+
 class CsharpNameResolver:
     """Namespace/using/alias-aware C# simple-name resolution.
 
@@ -227,6 +256,26 @@ def __init__(self, all_nodes: list[dict], all_edges: list[dict]) -> None:
                     if entry not in bucket:
                         bucket.append(entry)
 
+        # Blazor ``_Imports.razor`` (#3187): the Razor compiler applies its
+        # ``@using``/alias directives to every Razor file in the same directory
+        # and below, and the standard Blazor template keeps the app's
+        # namespaces there — so without this a bare ``@inject WidgetService``
+        # in a page dangles even though the canonical definition is in the
+        # graph. Index each _Imports.razor's directives by the directory they
+        # govern; razor-family lookups fold them in.
+        self._razor_dir_usings: list[tuple[str, list[tuple[str, str, str | None]]]] = []
+        self._razor_dir_aliases: list[
+            tuple[str, dict[str, list[tuple[str, str, str | None]]]]
+        ] = []
+        for sf, entries in self.namespace_usings_by_file.items():
+            d = _razor_imports_dir(sf)
+            if d is not None:
+                self._razor_dir_usings.append((d, entries))
+        for sf, alias_map in self.aliases_by_file.items():
+            d = _razor_imports_dir(sf)
+            if d is not None:
+                self._razor_dir_aliases.append((d, alias_map))
+
     @staticmethod
     def _namespace(node: dict | None) -> str:
         metadata = _metadata((node or {}).get("metadata"))
@@ -243,6 +292,46 @@ def _using_in_scope(self, scope_kind: str, scope_id: str | None, source_node: di
             return True
         return scope_id is not None and scope_id in self._scope_chain(source_node)
 
+    @staticmethod
+    def _is_razor_family(source_file: str) -> bool:
+        return isinstance(source_file, str) and source_file.lower().endswith(
+            (".razor", ".cshtml")
+        )
+
+    def _inherited_razor_usings(
+        self, source_file: str
+    ) -> list[tuple[str, str, str | None]]:
+        if not self._razor_dir_usings or not self._is_razor_family(source_file):
+            return []
+        out: list[tuple[str, str, str | None]] = []
+        for d, entries in self._razor_dir_usings:
+            if _razor_dir_applies(d, source_file):
+                for entry in entries:
+                    if entry not in out:
+                        out.append(entry)
+        return out
+
+    def _aliases_for(
+        self, source_file: str
+    ) -> dict[str, list[tuple[str, str, str | None]]]:
+        own = self.aliases_by_file.get(source_file, {})
+        if not self._razor_dir_aliases or not self._is_razor_family(source_file):
+            return own
+        inherited = [
+            alias_map for d, alias_map in self._razor_dir_aliases
+            if _razor_dir_applies(d, source_file)
+        ]
+        if not inherited:
+            return own
+        merged = {alias: list(entries) for alias, entries in own.items()}
+        for alias_map in inherited:
+            for alias, entries in alias_map.items():
+                bucket = merged.setdefault(alias, [])
+                for entry in entries:
+                    if entry not in bucket:
+                        bucket.append(entry)
+        return merged
+
     def _scopes_for(self, source_node: dict, source_file: str) -> list[str]:
         def _append_unique(items: list[str], value: str) -> None:
             if value not in items:
@@ -254,11 +343,14 @@ def _append_unique(items: list[str], value: str) -> None:
         for namespace, scope_kind, scope_id in self.namespace_usings_by_file.get(source_file, []):
             if self._using_in_scope(scope_kind, scope_id, source_node):
                 _append_unique(scopes, namespace)
+        for namespace, scope_kind, scope_id in self._inherited_razor_usings(source_file):
+            if self._using_in_scope(scope_kind, scope_id, source_node):
+                _append_unique(scopes, namespace)
         return scopes
 
     def _resolve_alias(self, label: str, source_node: dict, source_file: str) -> str | None:
         hits = set()
-        for target_fqn, scope_kind, scope_id in self.aliases_by_file.get(source_file, {}).get(label, []):
+        for target_fqn, scope_kind, scope_id in self._aliases_for(source_file).get(label, []):
             if not self._using_in_scope(scope_kind, scope_id, source_node):
                 continue
             base_fqn = _strip_trailing_csharp_generic_args(html.unescape(target_fqn))
@@ -286,7 +378,7 @@ def resolve_type_name(
           * ``(None, False)`` — scoping knows nothing about the name; a caller
             may fall back (e.g. to the corpus-wide unique bare-name match).
         """
-        if label in self.aliases_by_file.get(source_file, {}):
+        if label in self._aliases_for(source_file):
             return self._resolve_alias(label, source_node, source_file), True
         candidates: list[str] = []
         for namespace in self._scopes_for(source_node, source_file):
@@ -310,7 +402,7 @@ def resolve_qualified(
         if not isinstance(qualifier, str) or not qualifier:
             return None
         in_scope = [
-            entry for entry in self.aliases_by_file.get(source_file, {}).get(qualifier, [])
+            entry for entry in self._aliases_for(source_file).get(qualifier, [])
             if self._using_in_scope(entry[1], entry[2], source_node)
         ]
         if in_scope:
diff --git a/tests/test_razor_imports_usings.py b/tests/test_razor_imports_usings.py
new file mode 100644
index 000000000..fb69fdf10
--- /dev/null
+++ b/tests/test_razor_imports_usings.py
@@ -0,0 +1,161 @@
+"""Blazor ``_Imports.razor`` global usings reach the C# resolver (#3187).
+
+#3188 routed a Razor ``@inject`` through the C# cross-file type resolver, but
+only directives written in the page itself counted. The Razor compiler applies
+``_Imports.razor`` ``@using``/alias directives to every Razor file in the same
+directory and below — and the standard Blazor template keeps the app's
+namespaces there, so a bare ``@inject WidgetService _w`` in a page dangled on
+a sourceless stub even though the canonical definition was in the graph.
+"""
+
+from graphify.extract import collect_files, extract
+
+SERVICE_CS = (
+    "namespace Demo.Services;\n\n"
+    "public class WidgetService\n{\n"
+    '    public string GetName() => "widget";\n'
+    "}\n"
+)
+
+ALPHA_RAZOR = (
+    '@page "/alpha"\n'
+    "@inject WidgetService _widgets\n\n"
+    "<p>@_widgets.GetName()</p>\n"
+)
+
+
+def _extract(td, files):
+    for rel, body in files.items():
+        p = td / rel
+        p.parent.mkdir(parents=True, exist_ok=True)
+        p.write_text(body, encoding="utf-8")
+    return extract(collect_files(td), cache_root=td, parallel=False)
+
+
+def _canonical_id(r):
+    return next(
+        n["id"] for n in r["nodes"]
+        if n.get("label") == "WidgetService"
+        and str(n.get("source_file", "")).endswith(".cs")
+        and (n.get("metadata") or {}).get("namespace") == "Demo.Services"
+    )
+
+
+def _razor_ref_targets(r, page_suffix=".razor"):
+    return {
+        e["target"] for e in r["edges"]
+        if e.get("relation") == "references"
+        and str(e.get("source_file", "")).endswith(page_suffix)
+    }
+
+
+def test_same_directory_imports_razor_resolves_inject(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/AlphaPage.razor": ALPHA_RAZOR,
+        "Pages/_Imports.razor": "@using Demo.Services\n",
+    })
+    assert _canonical_id(r) in _razor_ref_targets(r)
+    stubs = [n for n in r["nodes"]
+             if n.get("label") == "WidgetService" and not n.get("source_file")]
+    assert stubs == [], f"sourceless stub survived: {stubs}"
+
+
+def test_root_imports_razor_governs_nested_pages(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/Admin/AlphaPage.razor": ALPHA_RAZOR,
+        "_Imports.razor": "@using Demo.Services\n",
+    })
+    assert _canonical_id(r) in _razor_ref_targets(r)
+
+
+def test_sibling_directory_imports_razor_does_not_apply(tmp_path, monkeypatch):
+    """An _Imports.razor in an unrelated sibling directory must not leak in."""
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/AlphaPage.razor": ALPHA_RAZOR,
+        "Components/_Imports.razor": "@using Demo.Services\n",
+    })
+    assert _canonical_id(r) not in _razor_ref_targets(r), (
+        "a sibling directory's _Imports.razor must not govern this page"
+    )
+
+
+def test_cs_files_do_not_inherit_imports_razor(tmp_path, monkeypatch):
+    """The Razor compiler's rule is Razor-only: a .cs file in the same
+    directory must not gain the _Imports.razor usings."""
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/_Imports.razor": "@using Demo.Services\n",
+        "Pages/Helper.cs": (
+            "namespace Demo.Pages;\n\n"
+            "public class Helper\n{\n"
+            "    private readonly WidgetService _w;\n"
+            "    public Helper(WidgetService w) => _w = w;\n"
+            "}\n"
+        ),
+    })
+    cs_targets = {
+        e["target"] for e in r["edges"]
+        if e.get("relation") == "references"
+        and str(e.get("source_file", "")).endswith("Helper.cs")
+    }
+    assert _canonical_id(r) not in cs_targets, (
+        "a .cs file must not inherit _Imports.razor usings"
+    )
+
+
+def test_ambiguous_inherited_using_still_dangles(tmp_path, monkeypatch):
+    """Two same-named types both brought in scope via _Imports.razor usings:
+    no arbitrary winner."""
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "A/WidgetService.cs": (
+            "namespace Demo.A;\n\npublic class WidgetService { }\n"
+        ),
+        "B/WidgetService.cs": (
+            "namespace Demo.B;\n\npublic class WidgetService { }\n"
+        ),
+        "Pages/AlphaPage.razor": ALPHA_RAZOR,
+        "Pages/_Imports.razor": "@using Demo.A\n@using Demo.B\n",
+    })
+    razor_targets = _razor_ref_targets(r)
+    defined = {
+        n["id"] for n in r["nodes"]
+        if n.get("label") == "WidgetService" and n.get("source_file")
+    }
+    assert not (razor_targets & defined), (
+        "ambiguous inherited using must not pick a winner"
+    )
+
+
+def test_no_using_anywhere_still_dangles(tmp_path, monkeypatch):
+    """Control for the intentional behavior: with no using in scope the inject
+    dangles, matching a bare C# cross-namespace reference (that Razor file
+    would not compile either)."""
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/AlphaPage.razor": ALPHA_RAZOR,
+    })
+    assert _canonical_id(r) not in _razor_ref_targets(r)
+
+
+def test_imports_razor_alias_resolves(tmp_path, monkeypatch):
+    """An alias directive in _Imports.razor works like a page-local one."""
+    monkeypatch.chdir(tmp_path)
+    r = _extract(tmp_path, {
+        "Services/WidgetService.cs": SERVICE_CS,
+        "Pages/AlphaPage.razor": (
+            '@page "/alpha"\n'
+            "@inject Widgets _widgets\n\n"
+            "<p>@_widgets.GetName()</p>\n"
+        ),
+        "Pages/_Imports.razor": "@using Widgets = Demo.Services.WidgetService\n",
+    })
+    assert _canonical_id(r) in _razor_ref_targets(r)