fix TSamFailedOnly and the output formatting for the go-runner

tests/test_samurai_last_spec.lua

@@ -54,6 +54,57 @@ describe("TSamLast", function()
     assert.equals(calls[1].opts.cwd, calls[2].opts.cwd)
   end)
 
+  it("uses go parser for TSamLast output (no raw JSON)", function()
+    local json_line = vim.json.encode({
+      Action = "fail",
+      Test = "TestHandleGet/returns_200",
+    })
+
+    local calls = {}
+    local orig_jobstart = vim.fn.jobstart
+    vim.fn.jobstart = function(cmd, opts)
+      table.insert(calls, { cmd = cmd, opts = opts })
+      if opts and opts.on_stdout then
+        opts.on_stdout(1, { json_line }, nil)
+      end
+      if opts and opts.on_exit then
+        opts.on_exit(1, 1, nil)
+      end
+      return 1
+    end
+
+    local bufnr = mkbuf("/tmp/project/foo_last_output_test.go", "go", {
+      "package main",
+      "import \"testing\"",
+      "",
+      "func TestHandleGet(t *testing.T) {",
+      "  t.Run(\"returns_200\", func(t *testing.T) {",
+      "    -- inside test",
+      "  })",
+      "}",
+    })
+
+    vim.api.nvim_set_current_buf(bufnr)
+
+    core.run_all()
+    core.run_last()
+
+    local out_buf = vim.api.nvim_get_current_buf()
+    local lines = vim.api.nvim_buf_get_lines(out_buf, 0, -1, false)
+
+    vim.fn.jobstart = orig_jobstart
+
+    assert.equals(2, #calls)
+    local has_raw = false
+    for _, line in ipairs(lines) do
+      if line == json_line then
+        has_raw = true
+        break
+      end
+    end
+    assert.is_false(has_raw)
+  end)
+
   it("reruns last JS command", function()
     local calls, orig_jobstart = capture_jobstart()