fix(openviking): pre-check fs/stat to route file URIs before hitting directory-only endpoints

Adds a deterministic pre-check on top of htsh's exception-based fallback:
before calling /content/abstract or /content/overview on a non-pseudo URI,
probe /api/v1/fs/stat. If the server says the URI is a file, route straight
to /content/read instead of eating a failing 500 round-trip.

This is the same idea pty819 and chennest independently landed in PRs
#12757 and #12937 — merged here on top of htsh's broader fix so we keep
pseudo-URI normalization and v0.3.3 browse-shape handling while avoiding
the slow exception path on servers that return a raised 500 every time.

The exception fallback from #5886 stays in place for environments where
fs/stat is unavailable or returns an unfamiliar shape.

Also credits pty819, chennest, and htsh in AUTHOR_MAP so future release
notes attribute them correctly.

tests/openviking_plugin/test_openviking.py

@@ -71,11 +71,91 @@ class TestOpenVikingRead:
             {"uri": "viking://user/hermes/memories/profile.md"},
         )]
 
-    def test_overview_file_uri_falls_back_to_content_read_on_summary_error(self):
+    def test_overview_file_uri_routes_straight_to_content_read_via_stat_probe(self):
+        """Pre-check via fs/stat: file URIs skip the directory-only endpoint entirely."""
         provider = OpenVikingMemoryProvider()
         file_uri = "viking://user/hermes/memories/entities/mem_abc.md"
         provider._client = FakeVikingClient(
             {
+                (
+                    "/api/v1/fs/stat",
+                    (("uri", file_uri),),
+                ): {"result": {"isDir": False}},
+                (
+                    "/api/v1/content/read",
+                    (("uri", file_uri),),
+                ): {"result": {"content": "full content"}},
+            }
+        )
+
+        result = json.loads(provider._tool_read({"uri": file_uri, "level": "overview"}))
+
+        assert result["uri"] == file_uri
+        assert result["resolved_uri"] == file_uri
+        assert result["level"] == "overview"
+        assert result["fallback"] == "content/read"
+        assert result["content"] == "full content"
+        assert provider._client.calls == [
+            ("/api/v1/fs/stat", {"uri": file_uri}),
+            ("/api/v1/content/read", {"uri": file_uri}),
+        ]
+
+    def test_overview_dir_uri_skips_stat_when_pseudo_summary(self):
+        """Pseudo-URI path already resolves to dir, so no stat probe needed."""
+        provider = OpenVikingMemoryProvider()
+        provider._client = FakeVikingClient(
+            {
+                (
+                    "/api/v1/content/overview",
+                    (("uri", "viking://user/hermes"),),
+                ): {"result": "overview"},
+            }
+        )
+
+        result = json.loads(provider._tool_read({"uri": "viking://user/hermes/.overview.md", "level": "overview"}))
+
+        assert result["content"] == "overview"
+        # No fs/stat call — normalization already determined it's a directory.
+        assert provider._client.calls == [
+            ("/api/v1/content/overview", {"uri": "viking://user/hermes"}),
+        ]
+
+    def test_overview_directory_uri_uses_stat_probe_then_overview(self):
+        """Non-pseudo directory URI: stat → isDir=True → summary endpoint."""
+        provider = OpenVikingMemoryProvider()
+        dir_uri = "viking://user/hermes/memories"
+        provider._client = FakeVikingClient(
+            {
+                (
+                    "/api/v1/fs/stat",
+                    (("uri", dir_uri),),
+                ): {"result": {"isDir": True}},
+                (
+                    "/api/v1/content/overview",
+                    (("uri", dir_uri),),
+                ): {"result": "dir overview"},
+            }
+        )
+
+        result = json.loads(provider._tool_read({"uri": dir_uri, "level": "overview"}))
+
+        assert result["content"] == "dir overview"
+        assert "fallback" not in result
+        assert provider._client.calls == [
+            ("/api/v1/fs/stat", {"uri": dir_uri}),
+            ("/api/v1/content/overview", {"uri": dir_uri}),
+        ]
+
+    def test_overview_file_uri_falls_back_via_exception_when_stat_indeterminate(self):
+        """If fs/stat raises or returns unknown shape, legacy exception fallback still kicks in."""
+        provider = OpenVikingMemoryProvider()
+        file_uri = "viking://user/hermes/memories/entities/mem_abc.md"
+        provider._client = FakeVikingClient(
+            {
+                (
+                    "/api/v1/fs/stat",
+                    (("uri", file_uri),),
+                ): RuntimeError("stat unavailable"),
                 (
                     "/api/v1/content/overview",
                     (("uri", file_uri),),
@@ -90,11 +170,11 @@ class TestOpenVikingRead:
         result = json.loads(provider._tool_read({"uri": file_uri, "level": "overview"}))
 
         assert result["uri"] == file_uri
-        assert result["resolved_uri"] == file_uri
         assert result["level"] == "overview"
         assert result["fallback"] == "content/read"
         assert result["content"] == "fallback full content"
         assert provider._client.calls == [
+            ("/api/v1/fs/stat", {"uri": file_uri}),
             ("/api/v1/content/overview", {"uri": file_uri}),
             ("/api/v1/content/read", {"uri": file_uri}),
         ]