CheckBreakpoint should only stop at the first condition fulfillment line

lib/debug/breakpoint.rb

@@ -326,8 +326,13 @@ def setup
         next if ThreadClient.current.management?
         next if skip_path?(tp.path)
 
-        if safe_eval tp.binding, @cond
-          suspend
+        if safe_eval(tp.binding, @cond)
+          unless fulfilled_on_current_thread?
+            set_fulfilled_on_current_thread
+            suspend
+          end
+        else
+          set_unfulfilled_on_current_thread
         end
       }
     end
@@ -337,6 +342,20 @@ def to_s
       s += super
       s
     end
+
+    private
+
+    def fulfilled_on_current_thread?
+      ThreadClient.current.check_bp_fulfilled?(self)
+    end
+
+    def set_fulfilled_on_current_thread
+      ThreadClient.current.set_check_bp_state(self, true)
+    end
+
+    def set_unfulfilled_on_current_thread
+      ThreadClient.current.set_check_bp_state(self, false)
+    end
   end
 
   class WatchIVarBreakpoint < Breakpoint

lib/debug/thread_client.rb

@@ -95,6 +95,8 @@ def initialize id, q_evt, q_cmd, thr = Thread.current
       @obj_map = {} # { object_id => obj } for CDP
       @recorder = nil
       @mode = :waiting
+      # every thread should maintain its own CheckBreakpoint fulfillment state
+      @check_bp_fulfillment_map = {} # { check_bp => boolean }
       set_mode :running
       thr.instance_variable_set(:@__thread_client_id, id)
 
@@ -337,6 +339,14 @@ def step_tp iter, events = [:line, :b_return, :return]
       end
     end
 
+    def set_check_bp_state(bp, state)
+      @check_bp_fulfillment_map[bp] = state
+    end
+
+    def check_bp_fulfilled?(bp)
+      @check_bp_fulfillment_map[bp]
+    end
+
     ## cmd helpers
 
     if TracePoint.respond_to? :allow_reentry

test/debug/break_test.rb

@@ -645,8 +645,11 @@ def program
      2| a += 1
      3| a += 2
      4| a += 3
-     5|
-     6| binding.b
+     5| a = 0
+     6| a = 1
+     7| a = 2
+     8| a = 3
+     9| binding.b
       RUBY
     end
 
@@ -671,6 +674,22 @@ def test_conditional_breakpoint_shows_error
       end
     end
 
+    def test_conditional_breakpoint_ignores_unchanged_true_condition
+      debug_code(program) do
+        type 'break if: a > 0'
+        type 'c'
+        assert_line_num(2) # stopped by line 1
+        # the state remains fulfilled so the next 2 lines don't trigger stoppage
+        type 'c'
+        # line 5 changes the state. so the next true condition will stop the program again
+        assert_line_num(7) # stopped by line 6
+        type 'c'
+        # the state remains fulfilled again, so the line 7 doesn't trigger stoppage
+        assert_line_num(9)
+        type 'c'
+      end
+    end
+
     class PathOptionTest < TestCase
       def extra_file
         <<~RUBY
@@ -712,10 +731,6 @@ def test_the_path_option_supersede_skip_path_config
             assert_line_num(3)
             assert_line_text(/201/)
             type 'c'
-            # this stop is because check bp stops at every line after the condition is fulfilled, which is another issue
-            # see https://github.com/ruby/debug/issues/406 for more about the issue
-            assert_line_num(4)
-            type 'c'
           end
         end