PowerShell · yotsuda · Nov 27, 2025 · Jan 14, 2026 · Jan 14, 2026 · Jan 14, 2026
@@ -4161,13 +4161,16 @@ internal void Trace(string messageId, string resourceString, params object[] arg
 
         internal void TraceLine(IScriptExtent extent)
         {
-            string msg = PositionUtilities.BriefMessage(extent.StartScriptPosition);
+            string[] lines = PositionUtilities.BriefMessage(extent);
             InternalHostUserInterface ui = (InternalHostUserInterface)_context.EngineHostInterface.UI;
 
             ActionPreference pref = _context.PSDebugTraceStep ?
                 ActionPreference.Inquire : ActionPreference.Continue;
 
-            ui.WriteDebugLine(msg, ref pref);
+            foreach (string line in lines)
+            {
+                ui.WriteDebugLine(line, ref pref);
+            }
 
             if (pref == ActionPreference.Continue)
                 _context.PSDebugTraceStep = false;

@@ -281,6 +281,58 @@ internal static string BriefMessage(IScriptPosition position)
             return StringUtil.Format(ParserStrings.TraceScriptLineMessage, position.LineNumber, message.ToString());
         }
 
+        /// <summary>
+        /// Return messages for an extent that may span multiple lines.
+        /// For single-line extents, returns an array with one element:
+        ///     12+  >>>> $x + $b.
+        /// For multi-line extents (e.g., line continuation with backtick), returns an array with one element per line:
+        ///     12+  >>>> Write-Output "foo `
+        ///     13+  >>>> bar"
+        /// </summary>
+        internal static string[] BriefMessage(IScriptExtent extent)
+        {
+            // For single-line extents, delegate to the existing single-position method
+            if (extent.StartLineNumber == extent.EndLineNumber)
+            {
+                return new[] { BriefMessage(extent.StartScriptPosition) };
+            }
+
+            // For multi-line extents, include all lines
+            string[] lines = extent.Text.Split(new[] { "\r\n", "\r", "\n" }, StringSplitOptions.None);
+            string[] result = new string[lines.Length];
+            int lineNumber = extent.StartLineNumber;
+
+            for (int i = 0; i < lines.Length; i++)
+            {
+                string line = lines[i];
+                StringBuilder message = new StringBuilder(line);
+
+                // Insert the marker at the appropriate position
+                if (i == 0)
+                {
+                    // For the first line, insert at the start column
+                    if (extent.StartColumnNumber > message.Length + 1)
+                    {
+                        message.Append(" <<<< ");
+                    }
+                    else
+                    {
+                        message.Insert(extent.StartColumnNumber - 1, " >>>> ");
+                    }
+                }
+                else
+                {
+                    // For continuation lines, insert the marker at the beginning
+                    message.Insert(0, " >>>> ");
+                }
+
+                result[i] = StringUtil.Format(ParserStrings.TraceScriptLineMessage, lineNumber, message.ToString());
+                lineNumber++;
+            }
+
+            return result;
+        }
+
         internal static IScriptExtent NewScriptExtent(IScriptExtent start, IScriptExtent end)
         {
             if (start == end)

@@ -26,5 +26,59 @@ Describe "Set-PSDebug" -Tags "CI" {
                 [ClassWithDefaultCtor]::new()
             } | Should -Not -Throw
         }
+
+        It "Should trace all lines of a multiline command" {
+            $tempScript = Join-Path $TestDrive "multiline-trace.ps1"
+            $scriptContent = "Set-PSDebug -Trace 1`nWrite-Output `"foo ```nbar`""
+            Set-Content -Path $tempScript -Value $scriptContent -NoNewline
+
+            # Run in a separate process to capture trace output
+            $pinfo = [System.Diagnostics.ProcessStartInfo]::new()
+            $pinfo.FileName = (Get-Process -Id $PID).Path
+            $pinfo.Arguments = "-NoProfile -File `"$tempScript`""
+            $pinfo.RedirectStandardOutput = $true
+            $pinfo.UseShellExecute = $false
+
+            $process = [System.Diagnostics.Process]::new()
+            $process.StartInfo = $pinfo
+            $process.Start() | Should -BeTrue
+            $output = $process.StandardOutput.ReadToEnd()
+            $exited = $process.WaitForExit(5000)
+            if (-not $exited) {
+                $process.Kill()
+            }
+            $exited | Should -BeTrue -Because "process should exit within timeout"
+
+            # The debug trace for multiline commands should include all lines with DEBUG: prefix
+            $output | Should -Match 'DEBUG:.*Write-Output' -Because "debug output should contain the command with DEBUG: prefix"
+            $output | Should -Match 'DEBUG:.*bar"' -Because "debug output should contain the continuation line with DEBUG: prefix"
+        }
+
+        It "Should trace all lines of a multiline command with -Trace 2" {
+            $tempScript = Join-Path $TestDrive "multiline-trace2.ps1"
+            $scriptContent = "Set-PSDebug -Trace 2`nWrite-Output `"foo ```nbar`""
+            Set-Content -Path $tempScript -Value $scriptContent -NoNewline
+
+            # Run in a separate process to capture trace output
+            $pinfo = [System.Diagnostics.ProcessStartInfo]::new()
+            $pinfo.FileName = (Get-Process -Id $PID).Path
+            $pinfo.Arguments = "-NoProfile -File `"$tempScript`""
+            $pinfo.RedirectStandardOutput = $true
+            $pinfo.UseShellExecute = $false
+
+            $process = [System.Diagnostics.Process]::new()
+            $process.StartInfo = $pinfo
+            $process.Start() | Should -BeTrue
+            $output = $process.StandardOutput.ReadToEnd()
+            $exited = $process.WaitForExit(5000)
+            if (-not $exited) {
+                $process.Kill()
+            }
+            $exited | Should -BeTrue -Because "process should exit within timeout"
+
+            # The debug trace for multiline commands should include all lines with DEBUG: prefix
+            $output | Should -Match 'DEBUG:.*Write-Output' -Because "debug output should contain the command with DEBUG: prefix"
+            $output | Should -Match 'DEBUG:.*bar"' -Because "debug output should contain the continuation line with DEBUG: prefix"
+        }
     }
 }