fix: handle ctrl+c based interrupts while in prompt

internal/mire/post_process.go

@@ -9,14 +9,18 @@ import (
 var (
 	scriptStartPrefix = []byte("Script started on ")
 	scriptDonePrefix  = []byte("Script done on ")
+	shellPromptPrefix = []byte("\x1b[?2004h$ ")
 )
 
 const (
+	interruptByte = byte(0x03)
 	eofByte       = byte(0x04)
 	escByte       = byte(0x1b)
 	bellByte      = byte(0x07)
 )
 
+var interruptSuffix = []byte("^C\x1b[?2004l\r\x1b[?2004h\x1b[?2004l\r\r\n")
+
 func loadRecordedInput(path string) ([]byte, error) {
 	data, err := os.ReadFile(path)
 	if err != nil {
@@ -51,6 +55,62 @@ func loadRecordedOutput(path string) ([]byte, error) {
 	return stripTerminalTitlePrefixes(data), nil
 }
 
+func sanitizeInterrupts(input, output []byte) ([]byte, []byte) {
+	return sanitizeInterruptInput(input), sanitizeInterruptOutput(output)
+}
+
+func sanitizeInterruptInput(data []byte) []byte {
+	cleaned := make([]byte, 0, len(data))
+	lineStart := 0
+
+	for _, b := range data {
+		if b == interruptByte {
+			cleaned = cleaned[:lineStart]
+			continue
+		}
+
+		cleaned = append(cleaned, b)
+		if b == '\n' {
+			lineStart = len(cleaned)
+		}
+	}
+
+	return cleaned
+}
+
+func sanitizeInterruptOutput(data []byte) []byte {
+	cleaned := make([]byte, 0, len(data))
+	cursor := 0
+
+	for {
+		suffixStart := bytes.Index(data[cursor:], interruptSuffix)
+		if suffixStart == -1 {
+			cleaned = append(cleaned, data[cursor:]...)
+			return cleaned
+		}
+		suffixStart += cursor
+
+		promptStart := bytes.LastIndex(data[cursor:suffixStart], shellPromptPrefix)
+		if promptStart == -1 {
+			end := suffixStart + len(interruptSuffix)
+			cleaned = append(cleaned, data[cursor:end]...)
+			cursor = end
+			continue
+		}
+		promptStart += cursor
+
+		if bytes.IndexByte(data[promptStart+len(shellPromptPrefix):suffixStart], '\n') != -1 {
+			end := suffixStart + len(interruptSuffix)
+			cleaned = append(cleaned, data[cursor:end]...)
+			cursor = end
+			continue
+		}
+
+		cleaned = append(cleaned, data[cursor:promptStart]...)
+		cursor = suffixStart + len(interruptSuffix)
+	}
+}
+
 func hasScriptWrapper(data []byte) bool {
 	if bytes.HasPrefix(data, scriptStartPrefix) {
 		return true

internal/mire/record_session.go

@@ -57,6 +57,7 @@ func recordScenario(target, shellPath string, rio recordIO, sandboxConfig map[st
 	if err != nil {
 		return err
 	}
+	recordedIn, recordedOut = sanitizeInterrupts(recordedIn, recordedOut)
 
 	if err := os.WriteFile(filepath.Join(target, "in"), recordedIn, 0o644); err != nil {
 		return err

internal/mire/record_test.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"mire/internal/testutil"
 )
@@ -315,6 +316,94 @@ func TestRecordScenarioUsesDeterministicSandbox(t *testing.T) {
 	}
 }
 
+func TestRecordScenarioStripsInterruptsFromSavedFixtures(t *testing.T) {
+	testutil.RequireCommands(t, "bwrap", "bash")
+
+	root := t.TempDir()
+	testDir := filepath.Join(root, "e2e")
+	target := filepath.Join(testDir, "suite", "spec")
+	testutil.MustMkdirAll(t, target)
+	mustWriteRecordShell(t, testDir)
+
+	err := testutil.WithWorkingDir(t, root, func() error {
+		reader, writer, pipeErr := os.Pipe()
+		if pipeErr != nil {
+			t.Fatalf("os.Pipe() error = %v", pipeErr)
+		}
+		t.Cleanup(func() {
+			_ = reader.Close()
+			_ = writer.Close()
+		})
+
+		errWriter := &promptSignalBuffer{
+			marker: "Save recording?",
+			ready:  make(chan struct{}),
+		}
+
+		writeDone := make(chan error, 1)
+		go func() {
+			defer close(writeDone)
+			defer writer.Close()
+
+			for _, chunk := range []struct {
+				data  string
+				delay time.Duration
+			}{
+				{data: "echo a\n", delay: 100 * time.Millisecond},
+				{data: "echo ", delay: 100 * time.Millisecond},
+				{data: "\x03", delay: 100 * time.Millisecond},
+				{data: "exit\n", delay: 0},
+			} {
+				if _, err := writer.Write([]byte(chunk.data)); err != nil {
+					writeDone <- err
+					return
+				}
+				if chunk.delay > 0 {
+					time.Sleep(chunk.delay)
+				}
+			}
+
+			<-errWriter.ready
+
+			if _, err := writer.Write([]byte("y\n")); err != nil {
+				writeDone <- err
+				return
+			}
+
+			writeDone <- nil
+		}()
+
+		err := recordScenario(target, recordShellPath(testDir), recordIO{
+			in:  reader,
+			out: ioDiscard{},
+			err: errWriter,
+		}, defaultSandboxConfig(), nil, nil, nil)
+		if writeErr := <-writeDone; writeErr != nil {
+			t.Fatalf("write record input: %v", writeErr)
+		}
+		return err
+	})
+	if err != nil {
+		t.Fatalf("recordScenario() error = %v", err)
+	}
+
+	recordedIn := testutil.ReadFile(t, filepath.Join(target, "in"))
+	if recordedIn != "echo a\nexit\n" {
+		t.Fatalf("saved in = %q, want %q", recordedIn, "echo a\nexit\n")
+	}
+
+	recordedOut := testutil.ReadFile(t, filepath.Join(target, "out"))
+	if strings.Contains(recordedOut, "^C") {
+		t.Fatalf("saved out = %q, want interrupt output removed", recordedOut)
+	}
+	if strings.Contains(recordedOut, "echo exit\r\n") {
+		t.Fatalf("saved out = %q, want interrupted line removed before exit", recordedOut)
+	}
+	if !strings.Contains(recordedOut, "exit\r\n") {
+		t.Fatalf("saved out = %q, want exit preserved", recordedOut)
+	}
+}
+
 func TestRecordFailsWhenRecorderShellMissing(t *testing.T) {
 	root := t.TempDir()
 	testDir := filepath.Join(root, "e2e")