Save and restore thread-locals in Capture#run and with_id

Three scope helpers in StdoutRouter hard-reset thread state on exit
instead of restoring the value they replaced:

* Capture#run set Thread.current.report_on_exception = false and never
  restored it, permanently disabling exception reporting on any thread
  that ran a capture.
* Capture#run reset :cliui_current_capture to nil, so a nested capture
  left the still-active outer capture invisible to current_capture
  consumers such as in_alternate_screen.
* with_id reset :cliui_output_id to nil, so a nested ID scope stripped
  the outer scope's output labelling for the rest of the outer block.

Save the previous value and restore it in the ensure block, matching
how Capture#run already handles :no_cliui_frame_inset and
:cliui_output_hook.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: GoodForOneFare

lib/cli/ui/stdout_router.rb

@@ -209,12 +209,14 @@ def run
 
           StdoutRouter.assert_enabled!
 
+          prev_capture = Thread.current[:cliui_current_capture]
           Thread.current[:cliui_current_capture] = self
 
           prev_frame_inset = Thread.current[:no_cliui_frame_inset]
           prev_hook = Thread.current[:cliui_output_hook]
 
           if Thread.current.respond_to?(:report_on_exception)
+            prev_report_on_exception = Thread.current.report_on_exception
             Thread.current.report_on_exception = false
           end
 
@@ -238,7 +240,10 @@ def run
         ensure
           Thread.current[:cliui_output_hook] = prev_hook
           Thread.current[:no_cliui_frame_inset] = prev_frame_inset
-          Thread.current[:cliui_current_capture] = nil
+          Thread.current[:cliui_current_capture] = prev_capture
+          unless prev_report_on_exception.nil?
+            Thread.current.report_on_exception = prev_report_on_exception
+          end
         end
 
         #: -> String
@@ -318,6 +323,7 @@ class << self
         def with_id(on_streams:, &block)
           require 'securerandom'
           id = format('%05d', rand(10**5))
+          prev_id = Thread.current[:cliui_output_id]
           Thread.current[:cliui_output_id] = {
             id: id,
             streams: on_streams.map do |stream|
@@ -326,7 +332,7 @@ def with_id(on_streams:, &block)
           }
           yield(id)
         ensure
-          Thread.current[:cliui_output_id] = nil
+          Thread.current[:cliui_output_id] = prev_id
         end
 
         #: -> Hash[Symbol, (String | io_like)]?

test/cli/ui/stdout_router_test.rb

@@ -24,6 +24,53 @@ def test_current_id
         end
       end
 
+      def test_nested_with_id_restores_outer_id
+        StdoutRouter.with_id(on_streams: [$stdout]) do |outer_id|
+          StdoutRouter.with_id(on_streams: [$stdout]) do |inner_id|
+            assert_equal(inner_id, StdoutRouter.current_id&.fetch(:id))
+          end
+          assert_equal(outer_id, StdoutRouter.current_id&.fetch(:id))
+        end
+        assert_nil(StdoutRouter.current_id)
+      end
+
+      def test_capture_restores_report_on_exception
+        capture_io do
+          StdoutRouter.with_enabled do
+            prev = Thread.current.report_on_exception
+            begin
+              Thread.current.report_on_exception = true
+              during = nil
+              StdoutRouter::Capture.new { during = Thread.current.report_on_exception }.run
+              assert_equal(false, during)
+              assert_equal(true, Thread.current.report_on_exception)
+            ensure
+              Thread.current.report_on_exception = prev
+            end
+          end
+        end
+      end
+
+      def test_nested_capture_restores_outer_capture
+        capture_io do
+          StdoutRouter.with_enabled do
+            inner_current = nil
+            restored_current = nil
+            inner = StdoutRouter::Capture.new do
+              inner_current = StdoutRouter::Capture.current_capture
+            end
+            outer = StdoutRouter::Capture.new do
+              inner.run
+              restored_current = StdoutRouter::Capture.current_capture
+            end
+            outer.run
+            assert_same(inner, inner_current)
+            assert_same(outer, restored_current)
+            assert_nil(StdoutRouter::Capture.current_capture)
+          end
+        end
+      end
+
       def test_frame_can_autoload_after_router_is_enabled
         script = <<~RUBY
           require 'stringio'