diff --git a/.dialyzer_ignore.exs b/.dialyzer_ignore.exs
index 8a5cfd5..a8c0620 100644
--- a/.dialyzer_ignore.exs
+++ b/.dialyzer_ignore.exs
@@ -2,6 +2,8 @@
   # Mix.Task behaviour info not available in dialyzer context
   {"lib/mix/tasks/jido_shell.ex", :callback_info_missing},
   {"lib/mix/tasks/jido_shell.ex", :unknown_function},
+  {"lib/mix/tasks/jido_shell.guardrails.ex", :callback_info_missing},
+  {"lib/mix/tasks/jido_shell.guardrails.ex", :unknown_function},
   {"lib/mix/tasks/jido_shell.install.ex", :callback_info_missing},
   {"lib/mix/tasks/jido_shell.install.ex", :unknown_function}
 ]
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a7d901a..fef136c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,6 +11,14 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  guardrails:
+    name: Guardrails
+    uses: agentjido/github-actions/.github/workflows/elixir-test.yml@main
+    with:
+      otp_versions: '["27"]'
+      elixir_versions: '["1.18"]'
+      test_command: mix jido_shell.guardrails
+
   lint:
     name: Lint
     uses: agentjido/github-actions/.github/workflows/elixir-lint.yml@main
diff --git a/AGENTS.md b/AGENTS.md
index 19b1c4f..50d4e69 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -12,6 +12,7 @@ mix compile --warnings-as-errors
 mix test
 mix test --include flaky
 mix coveralls
+mix jido_shell.guardrails
 mix quality
 mix docs
 mix jido_shell
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 179bcf3..b00bbd1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -16,12 +16,15 @@ mix test
 Run before opening a PR:
 
 ```bash
+mix jido_shell.guardrails
 mix quality
 mix test
 mix test --include flaky
 mix coveralls
 ```
 
+`mix quality` runs `mix jido_shell.guardrails` first, so namespace/layout regressions fail early in scripted workflows.
+
 ## Common Commands
 
 ```bash
@@ -38,6 +41,7 @@ mix docs
 2. Add tests for behavior changes.
 3. Keep docs and examples in sync.
 4. Use conventional commits.
+5. If module namespace/layout conventions change, update guardrails and guardrail tests in the same PR.
 
 Examples:
 
diff --git a/lib/jido/shell/guardrails.ex b/lib/jido/shell/guardrails.ex
new file mode 100644
index 0000000..63350a1
--- /dev/null
+++ b/lib/jido/shell/guardrails.ex
@@ -0,0 +1,70 @@
+defmodule Jido.Shell.Guardrails do
+  @moduledoc """
+  Runs namespace and layout guardrails for the `jido_shell` codebase.
+  """
+
+  alias Jido.Shell.Guardrails.Violation
+
+  @default_rules [
+    Jido.Shell.Guardrails.Rules.ForbiddenPaths,
+    Jido.Shell.Guardrails.Rules.RequiredFiles,
+    Jido.Shell.Guardrails.Rules.NamespacePrefixes
+  ]
+
+  @type options :: [
+          root: String.t(),
+          rules: [module()]
+        ]
+
+  @spec check(options()) :: :ok | {:error, [Violation.t()]}
+  def check(opts \\ []) do
+    context = %{root: normalize_root(opts)}
+
+    violations =
+      opts
+      |> rules()
+      |> Enum.flat_map(&run_rule(&1, context))
+      |> Enum.sort_by(fn %Violation{file: file, message: message} ->
+        {file || "", message}
+      end)
+
+    case violations do
+      [] -> :ok
+      _ -> {:error, violations}
+    end
+  end
+
+  @spec default_rules() :: [module()]
+  def default_rules, do: @default_rules
+
+  @spec format_violations([Violation.t()]) :: String.t()
+  def format_violations(violations) do
+    Enum.map_join(violations, "\n", fn %Violation{rule: rule, file: file, message: message} ->
+      location = if file, do: " (#{file})", else: ""
+      "[#{inspect(rule)}]#{location} #{message}"
+    end)
+  end
+
+  defp normalize_root(opts) do
+    opts
+    |> Keyword.get(:root, File.cwd!())
+    |> Path.expand()
+  end
+
+  defp rules(opts) do
+    Keyword.get(opts, :rules, @default_rules)
+  end
+
+  defp run_rule(rule, context) when is_atom(rule) do
+    Code.ensure_loaded(rule)
+
+    unless function_exported?(rule, :check, 1) do
+      raise ArgumentError, "guardrail rule #{inspect(rule)} must define check/1"
+    end
+
+    case rule.check(context) do
+      :ok -> []
+      violations when is_list(violations) -> violations
+    end
+  end
+end
diff --git a/lib/jido/shell/guardrails/rule.ex b/lib/jido/shell/guardrails/rule.ex
new file mode 100644
index 0000000..04b103a
--- /dev/null
+++ b/lib/jido/shell/guardrails/rule.ex
@@ -0,0 +1,13 @@
+defmodule Jido.Shell.Guardrails.Rule do
+  @moduledoc """
+  Behaviour for guardrail rules.
+  """
+
+  alias Jido.Shell.Guardrails.Violation
+
+  @type context :: %{
+          root: String.t()
+        }
+
+  @callback check(context()) :: :ok | [Violation.t()]
+end
diff --git a/lib/jido/shell/guardrails/rules/forbidden_paths.ex b/lib/jido/shell/guardrails/rules/forbidden_paths.ex
new file mode 100644
index 0000000..400f2d6
--- /dev/null
+++ b/lib/jido/shell/guardrails/rules/forbidden_paths.ex
@@ -0,0 +1,25 @@
+defmodule Jido.Shell.Guardrails.Rules.ForbiddenPaths do
+  @moduledoc false
+  @behaviour Jido.Shell.Guardrails.Rule
+
+  alias Jido.Shell.Guardrails.Violation
+
+  @forbidden_paths [
+    "lib/kodo",
+    "test/kodo",
+    "lib/mix/tasks/kodo.ui.ex"
+  ]
+
+  @impl true
+  def check(%{root: root}) do
+    @forbidden_paths
+    |> Enum.filter(&(root |> Path.join(&1) |> File.exists?()))
+    |> Enum.map(fn path ->
+      %Violation{
+        rule: __MODULE__,
+        file: path,
+        message: "legacy namespace path exists: #{path}"
+      }
+    end)
+  end
+end
diff --git a/lib/jido/shell/guardrails/rules/namespace_prefixes.ex b/lib/jido/shell/guardrails/rules/namespace_prefixes.ex
new file mode 100644
index 0000000..4c81046
--- /dev/null
+++ b/lib/jido/shell/guardrails/rules/namespace_prefixes.ex
@@ -0,0 +1,61 @@
+defmodule Jido.Shell.Guardrails.Rules.NamespacePrefixes do
+  @moduledoc false
+  @behaviour Jido.Shell.Guardrails.Rule
+
+  alias Jido.Shell.Guardrails.Violation
+
+  @module_pattern ~r/^\s*defmodule\s+([A-Za-z0-9_.]+)\s+do/m
+
+  @file_prefix_rules [
+    {"lib/jido/shell/**/*.ex", "Jido.Shell"},
+    {"lib/mix/tasks/jido_shell*.ex", "Mix.Tasks.JidoShell"}
+  ]
+
+  @impl true
+  def check(%{root: root}) do
+    Enum.flat_map(@file_prefix_rules, fn {glob, prefix} ->
+      root
+      |> Path.join(glob)
+      |> Path.wildcard()
+      |> Enum.flat_map(fn file ->
+        relative = Path.relative_to(file, root)
+        file_namespace_violations(file, relative, prefix)
+      end)
+    end)
+  end
+
+  defp file_namespace_violations(file, relative, prefix) do
+    modules =
+      file
+      |> File.read!()
+      |> modules_in_file()
+
+    case modules do
+      [] ->
+        [
+          %Violation{
+            rule: __MODULE__,
+            file: relative,
+            message: "no module definition found for namespace check"
+          }
+        ]
+
+      _ ->
+        modules
+        |> Enum.reject(&String.starts_with?(&1, prefix))
+        |> Enum.map(fn module_name ->
+          %Violation{
+            rule: __MODULE__,
+            file: relative,
+            message: "module #{module_name} does not use expected prefix #{prefix}"
+          }
+        end)
+    end
+  end
+
+  defp modules_in_file(contents) do
+    @module_pattern
+    |> Regex.scan(contents, capture: :all_but_first)
+    |> Enum.map(fn [module_name] -> module_name end)
+  end
+end
diff --git a/lib/jido/shell/guardrails/rules/required_files.ex b/lib/jido/shell/guardrails/rules/required_files.ex
new file mode 100644
index 0000000..46ae51d
--- /dev/null
+++ b/lib/jido/shell/guardrails/rules/required_files.ex
@@ -0,0 +1,59 @@
+defmodule Jido.Shell.Guardrails.Rules.RequiredFiles do
+  @moduledoc false
+  @behaviour Jido.Shell.Guardrails.Rule
+
+  alias Jido.Shell.Guardrails.Violation
+
+  @required_content %{
+    "lib/jido/shell/shell_session.ex" => [
+      "defmodule Jido.Shell.ShellSession do"
+    ],
+    "lib/jido/shell/shell_session_server.ex" => [
+      "defmodule Jido.Shell.ShellSessionServer do"
+    ],
+    "lib/jido/shell/shell_session/state.ex" => [
+      "defmodule Jido.Shell.ShellSession.State do"
+    ],
+    "lib/jido/shell/session.ex" => [
+      "defmodule Jido.Shell.Session do",
+      "@moduledoc deprecated:"
+    ],
+    "lib/jido/shell/session_server.ex" => [
+      "defmodule Jido.Shell.SessionServer do",
+      "@moduledoc deprecated:"
+    ],
+    "lib/jido/shell/session/state.ex" => [
+      "defmodule Jido.Shell.Session.State do",
+      "@moduledoc deprecated:"
+    ]
+  }
+
+  @impl true
+  def check(%{root: root}) do
+    Enum.flat_map(@required_content, fn {relative_path, snippets} ->
+      full_path = Path.join(root, relative_path)
+
+      case File.read(full_path) do
+        {:ok, contents} ->
+          snippets
+          |> Enum.reject(&String.contains?(contents, &1))
+          |> Enum.map(fn snippet ->
+            %Violation{
+              rule: __MODULE__,
+              file: relative_path,
+              message: "missing expected content: #{snippet}"
+            }
+          end)
+
+        {:error, _reason} ->
+          [
+            %Violation{
+              rule: __MODULE__,
+              file: relative_path,
+              message: "missing required file"
+            }
+          ]
+      end
+    end)
+  end
+end
diff --git a/lib/jido/shell/guardrails/violation.ex b/lib/jido/shell/guardrails/violation.ex
new file mode 100644
index 0000000..09ad197
--- /dev/null
+++ b/lib/jido/shell/guardrails/violation.ex
@@ -0,0 +1,14 @@
+defmodule Jido.Shell.Guardrails.Violation do
+  @moduledoc """
+  Represents a single guardrail violation.
+  """
+
+  @enforce_keys [:rule, :message]
+  defstruct [:rule, :message, :file]
+
+  @type t :: %__MODULE__{
+          rule: module(),
+          message: String.t(),
+          file: String.t() | nil
+        }
+end
diff --git a/lib/mix/tasks/jido_shell.guardrails.ex b/lib/mix/tasks/jido_shell.guardrails.ex
new file mode 100644
index 0000000..9568750
--- /dev/null
+++ b/lib/mix/tasks/jido_shell.guardrails.ex
@@ -0,0 +1,39 @@
+defmodule Mix.Tasks.JidoShell.Guardrails do
+  @moduledoc """
+  Verifies namespace and file layout guardrails for this repository.
+
+  ## Usage
+
+      mix jido_shell.guardrails
+      mix jido_shell.guardrails --root /path/to/repo
+  """
+
+  use Mix.Task
+
+  @shortdoc "Check namespace/layout guardrails"
+
+  @impl Mix.Task
+  def run(args) do
+    {opts, _argv, _invalid} =
+      OptionParser.parse(args,
+        strict: [root: :string]
+      )
+
+    root = Keyword.get(opts, :root, File.cwd!())
+
+    case Jido.Shell.Guardrails.check(root: root) do
+      :ok ->
+        Mix.shell().info("jido_shell guardrails: ok")
+        :ok
+
+      {:error, violations} ->
+        formatted = Jido.Shell.Guardrails.format_violations(violations)
+
+        Mix.raise("""
+        jido_shell guardrails failed:
+
+        #{formatted}
+        """)
+    end
+  end
+end
diff --git a/mix.exs b/mix.exs
index ac5c707..3020023 100644
--- a/mix.exs
+++ b/mix.exs
@@ -95,6 +95,7 @@ defmodule Jido.Shell.MixProject do
       test: "test --exclude flaky",
       q: ["quality"],
       quality: [
+        "jido_shell.guardrails",
         "format --check-formatted",
         "compile --warnings-as-errors",
         "credo --min-priority higher",
diff --git a/test/jido/shell/guardrails_test.exs b/test/jido/shell/guardrails_test.exs
new file mode 100644
index 0000000..a397dee
--- /dev/null
+++ b/test/jido/shell/guardrails_test.exs
@@ -0,0 +1,64 @@
+defmodule Jido.Shell.GuardrailsTest do
+  use ExUnit.Case, async: true
+
+  alias Jido.Shell.Guardrails
+  alias Jido.Shell.Guardrails.Rules.ForbiddenPaths
+  alias Jido.Shell.Guardrails.Rules.NamespacePrefixes
+  alias Jido.Shell.Guardrails.Rules.RequiredFiles
+  alias Jido.Shell.Guardrails.Violation
+
+  test "passes for current repository layout" do
+    assert :ok = Guardrails.check(root: File.cwd!())
+  end
+
+  test "forbidden path rule flags legacy namespace paths" do
+    with_tmp_dir(fn root ->
+      legacy_file = Path.join(root, "lib/kodo/transport/term_ui.ex")
+      File.mkdir_p!(Path.dirname(legacy_file))
+      File.write!(legacy_file, "defmodule Kodo.Transport.TermUI do\nend\n")
+
+      assert {:error, violations} = Guardrails.check(root: root, rules: [ForbiddenPaths])
+
+      assert Enum.any?(violations, fn %Violation{file: file, message: message} ->
+               file == "lib/kodo" and String.contains?(message, "legacy namespace path exists")
+             end)
+    end)
+  end
+
+  test "required file rule flags missing canonical modules" do
+    with_tmp_dir(fn root ->
+      assert {:error, violations} = Guardrails.check(root: root, rules: [RequiredFiles])
+
+      assert Enum.any?(violations, fn %Violation{file: file, message: message} ->
+               file == "lib/jido/shell/shell_session.ex" and
+                 String.contains?(message, "missing required file")
+             end)
+    end)
+  end
+
+  test "namespace prefix rule flags incorrect module prefixes" do
+    with_tmp_dir(fn root ->
+      path = Path.join(root, "lib/jido/shell/command/bad.ex")
+      File.mkdir_p!(Path.dirname(path))
+      File.write!(path, "defmodule Kodo.Command.Bad do\nend\n")
+
+      assert {:error, violations} = Guardrails.check(root: root, rules: [NamespacePrefixes])
+
+      assert Enum.any?(violations, fn %Violation{file: file, message: message} ->
+               file == "lib/jido/shell/command/bad.ex" and
+                 String.contains?(message, "expected prefix Jido.Shell")
+             end)
+    end)
+  end
+
+  defp with_tmp_dir(fun) do
+    root = Path.join(System.tmp_dir!(), "jido-shell-guardrails-#{System.unique_integer([:positive])}")
+    File.mkdir_p!(root)
+
+    try do
+      fun.(root)
+    after
+      File.rm_rf!(root)
+    end
+  end
+end
diff --git a/test/mix/tasks/jido_shell.guardrails_test.exs b/test/mix/tasks/jido_shell.guardrails_test.exs
new file mode 100644
index 0000000..5b29119
--- /dev/null
+++ b/test/mix/tasks/jido_shell.guardrails_test.exs
@@ -0,0 +1,41 @@
+defmodule Mix.Tasks.JidoShell.GuardrailsTest do
+  use ExUnit.Case, async: false
+  import ExUnit.CaptureIO
+
+  setup do
+    Mix.Task.reenable("jido_shell.guardrails")
+    :ok
+  end
+
+  test "succeeds for current repository" do
+    output =
+      capture_io(fn ->
+        assert :ok = Mix.Tasks.JidoShell.Guardrails.run(["--root", File.cwd!()])
+      end)
+
+    assert output =~ "jido_shell guardrails: ok"
+  end
+
+  test "raises with formatted violations when guardrails fail" do
+    with_tmp_dir(fn root ->
+      legacy_file = Path.join(root, "lib/kodo/transport/term_ui.ex")
+      File.mkdir_p!(Path.dirname(legacy_file))
+      File.write!(legacy_file, "defmodule Kodo.Transport.TermUI do\nend\n")
+
+      assert_raise Mix.Error, ~r/jido_shell guardrails failed/, fn ->
+        Mix.Tasks.JidoShell.Guardrails.run(["--root", root])
+      end
+    end)
+  end
+
+  defp with_tmp_dir(fun) do
+    root = Path.join(System.tmp_dir!(), "jido-shell-mix-guardrails-#{System.unique_integer([:positive])}")
+    File.mkdir_p!(root)
+
+    try do
+      fun.(root)
+    after
+      File.rm_rf!(root)
+    end
+  end
+end