fix: keep read path validation model-visible

packages/core/test/location-filesystem.test.ts

@@ -67,6 +67,11 @@ describe("FileSystem", () => {
 
         expect(yield* service.read({ path: output })).toMatchObject({ type: "text", content: "failure here" })
         expect((yield* service.resolveRoot({ path: output })).real).toBe(output)
+        expect(
+          yield* service
+            .resolveReadPath({ path: unrelated })
+            .pipe(Effect.catchDefect((defect) => Effect.succeed(defect))),
+        ).toBeInstanceOf(FileSystem.PathValidationError)
         expect(yield* Effect.exit(service.read({ path: unrelated }))).toMatchObject({ _tag: "Failure" })
         expect(yield* Effect.exit(service.read({ path: managed }))).toMatchObject({ _tag: "Failure" })
       }).pipe(provide(worktree, inertReferences, FSUtil.defaultLayer, data))

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

@@ -490,6 +490,23 @@ describe("ReadTool", () => {
     }),
   )
 
+  it.effect("returns path validation failures as model-visible tool output", () =>
+    Effect.gen(function* () {
+      const registry = yield* ToolRegistry.Service
+
+      resolveFailure = new FileSystem.PathValidationError("Absolute path is not managed tool output")
+      expect(
+        yield* executeTool(registry, {
+          sessionID,
+          ...toolIdentity,
+          call: { type: "tool-call", id: "call-unmanaged", name: "read", input: { path: "/tmp/private.txt" } },
+        }),
+      ).toEqual({ type: "error", value: "Absolute path is not managed tool output" })
+
+      expect(readCalls).toEqual([])
+    }),
+  )
+
   it.effect("forwards pagination and returns bounded text pages with continuation", () =>
     Effect.gen(function* () {
       readResult = new FileSystem.TextPage({