fix: strip trailing recorder-stop noise in PlayerEngine (#14)

box-v7 패턴: alt+tab → click(PowerShell) → ctrl+c ctrl+c 가 재생 시
SUT 외부 창(브라우저 등)에 입력을 보내는 버그.

- PlayerEngine.Run: trailing (alt+tab → optional click → ctrl+c+) 감지 시 제거
- leading alt+tab 제거와 대칭적으로 동작
- ctrl+c 단독으로는 제거하지 않음 (SUT 내 복사 액션과 구분)
- 테스트 2건 추가 (138 total)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Recordingtest.Player/PlayerEngine.cs

@@ -48,13 +48,48 @@ public sealed class PlayerEngine
             break;
         }
 
+        // Issue #14: strip trailing recorder-stop noise. The common recording
+        // stop sequence is: alt+tab (switch back to recorder terminal) →
+        // optional click (focus terminal) → ctrl+c (stop recorder).
+        // Replaying this after real work is done would shift focus out of the
+        // SUT and send ctrl+c to a random window (browser, etc.).
+        // Pattern: from the end, remove ctrl+c hotkeys, then remove at most one
+        // click, then remove at most one alt+tab — but ONLY if at least one
+        // alt+tab was found (i.e. the pattern starts with focus-switch noise).
+        int end = scenario.Steps.Count;
+        {
+            int t = end - 1;
+            // strip trailing ctrl+c
+            int ctrlcCount = 0;
+            while (t >= start &&
+                   scenario.Steps[t].Kind == StepKind.Hotkey &&
+                   string.Equals(scenario.Steps[t].Value, "ctrl+c", StringComparison.OrdinalIgnoreCase))
+            {
+                t--;
+                ctrlcCount++;
+            }
+            // strip optional trailing click
+            if (t >= start && scenario.Steps[t].Kind == StepKind.Click)
+                t--;
+            // strip trailing alt+tab — only commit the trim if we found one
+            if (t >= start &&
+                scenario.Steps[t].Kind == StepKind.Hotkey &&
+                string.Equals(scenario.Steps[t].Value, "alt+tab", StringComparison.OrdinalIgnoreCase) &&
+                ctrlcCount > 0)
+            {
+                end = t; // exclude alt+tab and everything after
+                Console.WriteLine(
+                    $"[player] info: stripped trailing recorder-stop noise (steps {t}..{scenario.Steps.Count - 1}) (issue #14)");
+            }
+        }
+
         // Seed prevTs so the FIRST executed step also gets a pre-delay
         // (MinStepDelay). Without this, step 2's Type can fire before the
         // SUT has fully settled after foreground switch.
-        long? prevTs = start < scenario.Steps.Count && scenario.Steps[start].Ts is long firstTs
+        long? prevTs = start < end && scenario.Steps[start].Ts is long firstTs
             ? firstTs - (long)_options.MinStepDelay.TotalMilliseconds
             : null;
-        for (int i = start; i < scenario.Steps.Count; i++)
+        for (int i = start; i < end; i++)
         {
             var step = scenario.Steps[i];
 

src/Recordingtest.Runner/Program.cs

@@ -19,12 +19,14 @@ public static class Program
                 case "--sidecar-url": sidecarUrl = args[++i]; break;
                 case "--no-sidecar": noSidecar = true; break;
                 case "--sidecar-profile": options.SidecarProfile = args[++i]; break;
+                case "--scenario": options.ScenarioFilter = args[++i]; break;
                 case "-h":
                 case "--help":
                     Console.WriteLine("Usage: Recordingtest.Runner --scenarios <dir> --baselines <dir> --out <dir>");
                     Console.WriteLine("                           [--profile <name>] [--no-launch]");
                     Console.WriteLine("                           [--sidecar-url http://localhost:38080] [--no-sidecar]");
                     Console.WriteLine("                           [--sidecar-profile engine-state]");
+                    Console.WriteLine("                           [--scenario <name>]  (run only this scenario)");
                     return 0;
             }
         }

src/Recordingtest.Runner/RunnerOptions.cs

@@ -9,4 +9,6 @@ public sealed class RunnerOptions
     /// <summary>Profile name for engine-state sidecar normalization. Defaults to "engine-state".</summary>
     public string SidecarProfile { get; set; } = "engine-state";
     public bool NoLaunch { get; set; }
+    /// <summary>If set, only run scenarios whose name matches this value (no extension).</summary>
+    public string? ScenarioFilter { get; set; }
 }

src/Recordingtest.Runner/TestRunner.cs

@@ -27,6 +27,8 @@ public sealed class TestRunner
 
         var yamlFiles = Directory.Exists(options.ScenariosDir)
             ? Directory.GetFiles(options.ScenariosDir, "*.yaml", SearchOption.TopDirectoryOnly)
+                .Where(p => options.ScenarioFilter is null ||
+                    Path.GetFileNameWithoutExtension(p).Equals(options.ScenarioFilter, StringComparison.OrdinalIgnoreCase))
                 .OrderBy(p => p, StringComparer.Ordinal).ToArray()
             : Array.Empty<string>();
 

tests/Recordingtest.Player.Tests/PlayerEngineTests.cs

@@ -221,6 +221,58 @@ steps:
         Assert.Equal(StepKind.Focus, s.Steps[1].Kind);
     }
 
+    // ---- trailing recorder-stop noise stripping --------------------------------
+
+    [Fact]
+    public void TrailingRecorderStop_AltTabClickCtrlC_Stripped()
+    {
+        // box-v7 pattern: real work → alt+tab → click → ctrl+c ctrl+c
+        var host = new FakePlayerHost();
+        var engine = new PlayerEngine(new PlayerEngineOptions { PreserveTiming = false });
+        var scenario = new Scenario
+        {
+            Steps =
+            {
+                new Step { Kind = StepKind.Type, Value = "BOX" },          // real work
+                new Step { Kind = StepKind.Hotkey, Value = "enter" },       // real work
+                new Step { Kind = StepKind.Hotkey, Value = "alt+tab" },     // recorder stop →
+                new Step { Kind = StepKind.Click, RawCoord = [771, 833] }, // click terminal
+                new Step { Kind = StepKind.Hotkey, Value = "ctrl+c" },     // stop recorder
+                new Step { Kind = StepKind.Hotkey, Value = "ctrl+c" },     // stop recorder
+            },
+        };
+
+        engine.Run(scenario, host);
+
+        // Only the two real-work steps should have fired — no Clicks, hotkey only "enter"
+        Assert.Empty(host.Clicks);                         // click (771,833) stripped
+        Assert.Single(host.Types);                         // only "BOX"
+        Assert.Equal("BOX", host.Types[0]);
+        Assert.Single(host.Hotkeys);                       // only "enter", not ctrl+c
+        Assert.Equal("enter", host.Hotkeys[0]);
+    }
+
+    [Fact]
+    public void TrailingCtrlCAlone_NotStripped_RequiresAltTab()
+    {
+        // ctrl+c without preceding alt+tab is a legitimate SUT action (copy)
+        var host = new FakePlayerHost();
+        var engine = new PlayerEngine(new PlayerEngineOptions { PreserveTiming = false });
+        var scenario = new Scenario
+        {
+            Steps =
+            {
+                new Step { Kind = StepKind.Type,   Value = "BOX" },
+                new Step { Kind = StepKind.Hotkey, Value = "ctrl+c" },
+            },
+        };
+
+        engine.Run(scenario, host);
+        // ctrl+c alone at the end must NOT be stripped (it's a copy action)
+        Assert.Single(host.Hotkeys);
+        Assert.Equal("ctrl+c", host.Hotkeys[0]);
+    }
+
     private static string LocateEngineSource([CallerFilePath] string here = "")
     {
         // here = .../tests/Recordingtest.Player.Tests/PlayerEngineTests.cs