fix(core): reject file glob roots (#38890)

packages/core/src/tool/glob.ts

@@ -83,13 +83,17 @@ export const Plugin = {
                   agent: context.agent,
                   source,
                 })
-                yield* fs
+                const info = yield* fs
                   .stat(target.canonical)
                   .pipe(
                     Effect.catchReason("PlatformError", "NotFound", () =>
                       Effect.fail(new ToolFailure({ message: `Search path does not exist: ${input.path ?? "."}` })),
                     ),
                   )
+                if (info.type !== "Directory")
+                  return yield* Effect.fail(
+                    new ToolFailure({ message: `Search path is not a directory: ${input.path ?? "."}` }),
+                  )
                 const root = path.resolve(location.directory, input.path ?? ".")
                 const limit = input.limit ?? FileSystem.DEFAULT_SEARCH_LIMIT
                 const entries = yield* ripgrep

packages/core/test/tool-search.test.ts

@@ -143,6 +143,29 @@ describe("search tools", () => {
     )
   }
 
+  it.live("reports a file used as the glob search path", () =>
+    Effect.acquireUseRelease(
+      Effect.promise(() => tmpdir()),
+      (tmp) =>
+        Effect.promise(() => fs.writeFile(path.join(tmp.path, "file.txt"), "content\n")).pipe(
+          Effect.andThen(
+            withTools(tmp.path, (registry) =>
+              executeTool(registry, call("glob", { path: "file.txt", pattern: "*" })),
+            ),
+          ),
+          Effect.tap((result) =>
+            Effect.sync(() => {
+              expect(result).toEqual({
+                status: "error",
+                error: { type: "tool.execution", message: "Search path is not a directory: file.txt" },
+              })
+            }),
+          ),
+        ),
+      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
+    ),
+  )
+
   it.live("requires external_directory approval for an explicit external glob path", () =>
     Effect.acquireUseRelease(
       Effect.promise(() => Promise.all([tmpdir(), tmpdir()])),