diff --git a/go.mod b/go.mod
index fcecba2..302512c 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module github.com/pingcap/ticat
 
 go 1.16
 
-require github.com/mattn/go-shellwords v1.0.11
+require (
+	github.com/mattn/go-shellwords v1.0.11
+	github.com/peterh/liner v1.2.1 // indirect
+)
diff --git a/go.sum b/go.sum
index 6042a20..cca446d 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,6 @@
+github.com/mattn/go-runewidth v0.0.3 h1:a+kO+98RDGEfo6asOGMmpodZq4FNtnGP54yps8BzLR4=
+github.com/mattn/go-runewidth v0.0.3/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/mattn/go-shellwords v1.0.11 h1:vCoR9VPpsk/TZFW2JwK5I9S0xdrtUq2bph6/YjEPnaw=
 github.com/mattn/go-shellwords v1.0.11/go.mod h1:EZzvwXDESEeg03EKmM+RmDnNOPKG4lLtQsUlTZDWQ8Y=
+github.com/peterh/liner v1.2.1 h1:O4BlKaq/LWu6VRWmol4ByWfzx6MfXc5Op5HETyIy5yg=
+github.com/peterh/liner v1.2.1/go.mod h1:CRroGNssyjTd/qIG2FyxByd2S8JEAZXBl4qUrZf8GS0=
diff --git a/pkg/builtin/builtin.go b/pkg/builtin/builtin.go
index d0c8dc2..9e3b390 100644
--- a/pkg/builtin/builtin.go
+++ b/pkg/builtin/builtin.go
@@ -710,6 +710,9 @@ func RegisterDbgCmds(cmds *core.CmdTree) {
 		AddArg("seconds", "3", "second", "sec", "s", "S")
 
 	breaks := cmds.AddSub("breaks", "break")
+	breaks.RegPowerCmd(DbgBreakAtBegin,
+		"set break point at the first command").
+		SetQuiet()
 
 	breaksAt := breaks.AddSub("at", "before").
 		RegPowerCmd(DbgBreakBefore,
@@ -723,6 +726,11 @@ func RegisterDbgCmds(cmds *core.CmdTree) {
 			"set break point at the first command").
 		SetQuiet()
 
+	breaksAt.AddSub("end", "finish").
+		RegPowerCmd(DbgBreakAtEnd,
+			"set break point after the last command").
+		SetQuiet()
+
 	breaks.AddSub("after", "post").
 		RegPowerCmd(DbgBreakAfter,
 			// TODO: get 'sep' from env or other config
@@ -753,8 +761,12 @@ func RegisterDbgCmds(cmds *core.CmdTree) {
 			"verify bash in os/exec").
 		SetQuiet()
 
-	cmds.AddSub("interact", "i", "I").
-		AddSub("leave", "l", "L").
+	interact := cmds.AddSub("interact", "interactive", "i", "I").
+		RegPowerCmd(DbgInteract,
+			"enter interact mode").
+		SetQuiet()
+
+	interact.AddSub("leave", "l", "L").
 		RegPowerCmd(DbgInteractLeave,
 			"leave interact mode and continue to run")
 
diff --git a/pkg/builtin/dbg.go b/pkg/builtin/dbg.go
index 6d47857..77fe967 100644
--- a/pkg/builtin/dbg.go
+++ b/pkg/builtin/dbg.go
@@ -7,7 +7,6 @@ import (
 	"strings"
 
 	"github.com/pingcap/ticat/pkg/cli/core"
-	//"github.com/pingcap/ticat/pkg/cli/display"
 )
 
 func DbgEcho(
@@ -88,6 +87,21 @@ func DbgBreakAtBegin(
 	return currCmdIdx, true
 }
 
+func DbgBreakAtEnd(
+	argv core.ArgVals,
+	cc *core.Cli,
+	env *core.Env,
+	flow *core.ParsedCmds,
+	currCmdIdx int) (int, bool) {
+
+	assertNotTailMode(flow, currCmdIdx)
+	cc.BreakPoints.SetAtEnd(true)
+	if 1 == len(flow.Cmds)-1 {
+		env.GetLayer(core.EnvLayerSession).SetBool("display.one-cmd", true)
+	}
+	return currCmdIdx, true
+}
+
 func DbgBreakBefore(
 	argv core.ArgVals,
 	cc *core.Cli,
@@ -131,3 +145,16 @@ func DbgInteractLeave(
 	env.SetBool("sys.interact.leaving", true)
 	return currCmdIdx, true
 }
+
+func DbgInteract(
+	argv core.ArgVals,
+	cc *core.Cli,
+	env *core.Env,
+	flow *core.ParsedCmds,
+	currCmdIdx int) (int, bool) {
+
+	assertNotTailMode(flow, currCmdIdx)
+
+	InteractiveMode(cc, env, "e")
+	return currCmdIdx, true
+}
diff --git a/pkg/builtin/interactive.go b/pkg/builtin/interactive.go
new file mode 100644
index 0000000..17cbf88
--- /dev/null
+++ b/pkg/builtin/interactive.go
@@ -0,0 +1,92 @@
+package builtin
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/peterh/liner"
+
+	"github.com/pingcap/ticat/pkg/cli/core"
+	"github.com/pingcap/ticat/pkg/cli/display"
+)
+
+func InteractiveMode(cc *core.Cli, env *core.Env, exitStr string) {
+	cc.Screen.Print(display.ColorExplain("(ctl-c to leave)\n", env))
+
+	cc = cc.CopyForInteract()
+	sessionEnv := env.GetLayer(core.EnvLayerSession)
+	sessionEnv.SetBool("sys.interact.inside", true)
+
+	seqSep := env.GetRaw("strs.seq-sep")
+	selfName := env.GetRaw("strs.self-name")
+
+	lineReader := liner.NewLiner()
+	defer lineReader.Close()
+	lineReader.SetCtrlCAborts(true)
+
+	names := cc.Cmds.GatherNames()
+	lineReader.SetCompleter(func(line string) (res []string) {
+		fields := strings.Fields(line)
+		field := strings.TrimLeft(fields[len(fields)-1], seqSep)
+		prefix := line[0 : len(line)-len(field)]
+		for _, name := range names {
+			if strings.HasPrefix(name, field) {
+				res = append(res, prefix+name)
+			}
+		}
+		return
+	})
+
+	historyDir := filepath.Join(os.TempDir(), ".ticat_interact_mode_cmds_history")
+	if file, err := os.Open(historyDir); err == nil {
+		lineReader.ReadHistory(file)
+		file.Close()
+	}
+
+	for {
+		if env.GetBool("sys.interact.leaving") {
+			break
+		}
+		line, err := lineReader.Prompt(selfName + "> ")
+		if err == liner.ErrPromptAborted {
+			break
+		}
+		if err != nil {
+			panic(fmt.Errorf("[InteractMode] read from stdin failed: %v", err))
+		}
+
+		lineReader.AppendHistory(line)
+		executorSafeExecute("(interact)", cc, env, nil, core.FlowStrToStrs(line)...)
+	}
+
+	sessionEnv.GetLayer(core.EnvLayerSession).Delete("sys.interact.inside")
+
+	file, err := os.Create(historyDir)
+	if err != nil {
+		panic(fmt.Errorf("[InteractMode] error writing history file: %v", err))
+	}
+	lineReader.WriteHistory(file)
+	file.Close()
+}
+
+func executorSafeExecute(caller string, cc *core.Cli, env *core.Env, masks []*core.ExecuteMask, input ...string) {
+	env = env.GetLayer(core.EnvLayerSession)
+	stackDepth := env.GetRaw("sys.stack-depth")
+	stack := env.GetRaw("sys.stack")
+
+	defer func() {
+		env.Set("sys.stack-depth", stackDepth)
+		env.Set("sys.stack", stack)
+
+		if !env.GetBool("sys.panic.recover") {
+			return
+		}
+		if r := recover(); r != nil {
+			display.PrintError(cc, env, r.(error))
+		}
+	}()
+
+	cc.Executor.Execute(caller, false, cc, env, masks, input...)
+}
diff --git a/pkg/cli/core/breakpoints.go b/pkg/cli/core/breakpoints.go
index 359e1a1..25141cb 100644
--- a/pkg/cli/core/breakpoints.go
+++ b/pkg/cli/core/breakpoints.go
@@ -5,17 +5,30 @@ import (
 )
 
 type BreakPoints struct {
-	Begin   bool
+	AtBegin bool
+	AtEnd   bool
 	Befores map[string]bool
 	Afters  map[string]bool
 }
 
 func NewBreakPoints() *BreakPoints {
-	return &BreakPoints{false, map[string]bool{}, map[string]bool{}}
+	return &BreakPoints{false, false, map[string]bool{}, map[string]bool{}}
 }
 
 func (self *BreakPoints) SetAtBegin(enabled bool) {
-	self.Begin = enabled
+	self.AtBegin = enabled
+}
+
+func (self *BreakPoints) BreakAtBegin() bool {
+	return self.AtBegin
+}
+
+func (self *BreakPoints) SetAtEnd(enabled bool) {
+	self.AtEnd = enabled
+}
+
+func (self *BreakPoints) BreakAtEnd() bool {
+	return self.AtEnd
 }
 
 func (self *BreakPoints) SetBefores(cc *Cli, env *Env, cmdList []string) (verifiedCmds []string) {
@@ -38,10 +51,6 @@ func (self *BreakPoints) SetAfters(cc *Cli, env *Env, cmdList []string) (verifie
 	return
 }
 
-func (self *BreakPoints) AtBegin() bool {
-	return self.Begin
-}
-
 func (self *BreakPoints) BreakBefore(cmd string) bool {
 	return self.Befores[cmd]
 }
diff --git a/pkg/cli/core/cli.go b/pkg/cli/core/cli.go
index cbf15f4..2d64954 100644
--- a/pkg/cli/core/cli.go
+++ b/pkg/cli/core/cli.go
@@ -33,7 +33,7 @@ func (self *ExecuteMask) Copy() *ExecuteMask {
 }
 
 type Executor interface {
-	Execute(caller string, cc *Cli, env *Env, masks []*ExecuteMask, input ...string) bool
+	Execute(caller string, inerrCall bool, cc *Cli, env *Env, masks []*ExecuteMask, input ...string) bool
 	Clone() Executor
 }
 
@@ -73,7 +73,7 @@ func NewCli(screen Screen, cmds *CmdTree, parser CliParser, abbrs *EnvAbbrs, cmd
 
 func (self *Cli) SetFlowStatusWriter(status *ExecutingFlow) {
 	if self.FlowStatus != nil {
-		panic(fmt.Errorf("[SetExecutingFlowStatusLogger] should never happen"))
+		panic(fmt.Errorf("[SetFlowStatusWriter] should never happen"))
 	}
 	self.FlowStatus = status
 }
diff --git a/pkg/cli/core/cmd.go b/pkg/cli/core/cmd.go
index 7681089..1afab3d 100644
--- a/pkg/cli/core/cmd.go
+++ b/pkg/cli/core/cmd.go
@@ -658,7 +658,7 @@ func (self *Cmd) executeFlow(argv ArgVals, cc *Cli, env *Env, mask *ExecuteMask)
 		masks = mask.SubFlow
 	}
 	if shouldExecByMask(mask) {
-		succeeded = cc.Executor.Execute(self.owner.DisplayPath(), cc, flowEnv, masks, flow...)
+		succeeded = cc.Executor.Execute(self.owner.DisplayPath(), true, cc, flowEnv, masks, flow...)
 	} else {
 		cc.Screen.Print("(skipped+)\n")
 		succeeded = true
diff --git a/pkg/cli/core/cmds.go b/pkg/cli/core/cmds.go
index 03991f0..9543a1a 100644
--- a/pkg/cli/core/cmds.go
+++ b/pkg/cli/core/cmds.go
@@ -131,6 +131,33 @@ func (self *CmdTree) MatchWriteKey(key string) bool {
 	return self.cmd.MatchWriteKey(key)
 }
 
+// TODO: slow
+func (self *CmdTree) GatherNames() (names []string) {
+	if self.parent == nil {
+		names = append(names, self.DisplayPath())
+	}
+	path := self.Path()
+	sep := self.Strs.PathSep
+
+	// Real names first, then abbrs
+	for sub, _ := range self.subs {
+		names = append(names, strings.Join(append(path, sub), sep))
+	}
+	for _, abbrs := range self.subAbbrs {
+		for _, abbr := range abbrs {
+			if _, ok := self.subs[abbr]; ok {
+				continue
+			}
+			names = append(names, strings.Join(append(path, abbr), sep))
+		}
+	}
+
+	for _, sub := range self.subs {
+		names = append(names, sub.GatherNames()...)
+	}
+	return names
+}
+
 func (self *CmdTree) RegCmd(cmd NormalCmd, help string) *Cmd {
 	self.cmdConflictCheck(help, "RegCmd")
 	self.cmd = NewCmd(self, help, cmd)
diff --git a/pkg/cli/display/flow.go b/pkg/cli/display/flow.go
index 77cdcba..3724619 100644
--- a/pkg/cli/display/flow.go
+++ b/pkg/cli/display/flow.go
@@ -725,10 +725,10 @@ func dumpExecutedModifiedEnv(
 		// TODO:
 		// return
 	}
-	if !args.ShowExecutedModifiedEnv && executedCmd.Result == core.ExecutedResultSucceeded {
+	if !args.ShowExecutedModifiedEnv && executedCmd.Result != core.ExecutedResultError {
 		return
 	}
-	if executedCmd.FinishEnv == nil && executedCmd.Result != core.ExecutedResultSucceeded {
+	if executedCmd.FinishEnv == nil && executedCmd.Result != core.ExecutedResultError {
 		return
 	}
 
diff --git a/pkg/cli/display/render.go b/pkg/cli/display/render.go
index 399d9a7..71d390f 100644
--- a/pkg/cli/display/render.go
+++ b/pkg/cli/display/render.go
@@ -156,15 +156,19 @@ func PrintSwitchingThreadDisplay(preTid string, info core.BgTaskInfo, env *core.
 func getFrameChars(env *core.Env) *FrameChars {
 	name := strings.ToLower(env.Get("display.style").Raw)
 	chars := getFrameCharsByName(env, name)
-	if env.GetInt("display.executor.displayed") == env.GetInt("sys.stack-depth") {
-		if env.GetBool("display.utf8") {
-			return FrameCharsAscii()
-		} else {
-			// TODO: have bugs
-			//return FrameCharsNoBorder()
-			return FrameCharsAscii()
+	// TODO: have bug
+	/*
+		// Display a lite frame under another frame
+		if env.GetInt("display.executor.displayed") == env.GetInt("sys.stack-depth") {
+			if env.GetBool("display.utf8") {
+				return FrameCharsAscii()
+			} else {
+				// TODO: have bugs
+				//return FrameCharsNoBorder()
+				return FrameCharsAscii()
+			}
 		}
-	}
+	*/
 	return chars
 }
 
diff --git a/pkg/cli/execute/cmd_type.go b/pkg/cli/execute/cmd_type.go
index d9c619b..56c4441 100644
--- a/pkg/cli/execute/cmd_type.go
+++ b/pkg/cli/execute/cmd_type.go
@@ -102,6 +102,7 @@ func noSessionCmds(flow *core.ParsedCmds) bool {
 	}
 
 	funcs := []interface{}{
+		builtin.DbgInteract,
 		builtin.SessionRetry,
 		//builtin.LastSessionRetry,
 	}
diff --git a/pkg/cli/execute/executor.go b/pkg/cli/execute/executor.go
index 667c52c..33e9f7b 100644
--- a/pkg/cli/execute/executor.go
+++ b/pkg/cli/execute/executor.go
@@ -53,6 +53,9 @@ func (self *Executor) Run(cc *core.Cli, env *core.Env, bootstrap string, input .
 		return false
 	}
 	ok := self.execute(self.callerNameEntry, cc, env, nil, false, false, input...)
+
+	tryBreakAtEnd(cc, env)
+
 	builtin.WaitAllBgTasks(cc, env)
 	if cc.FlowStatus != nil {
 		cc.FlowStatus.OnFlowFinish(ok)
@@ -61,8 +64,8 @@ func (self *Executor) Run(cc *core.Cli, env *core.Env, bootstrap string, input .
 }
 
 // Implement core.Executor
-func (self *Executor) Execute(caller string, cc *core.Cli, env *core.Env, masks []*core.ExecuteMask, input ...string) bool {
-	return self.execute(caller, cc, env, masks, false, true, input...)
+func (self *Executor) Execute(caller string, innerCall bool, cc *core.Cli, env *core.Env, masks []*core.ExecuteMask, input ...string) bool {
+	return self.execute(caller, cc, env, masks, false, innerCall, input...)
 }
 
 func (self *Executor) execute(caller string, cc *core.Cli, env *core.Env, masks []*core.ExecuteMask,
@@ -108,7 +111,7 @@ func (self *Executor) execute(caller string, cc *core.Cli, env *core.Env, masks
 
 	display.PrintTolerableErrs(cc.Screen, env, cc.TolerableErrs)
 
-	if !innerCall && !bootstrap {
+	if !innerCall && !bootstrap && !env.GetBool("sys.interact.inside") {
 		noSession := noSessionCmds(flow)
 		if !noSession {
 			statusWriter, ok := core.SessionInit(cc, flow, env, self.sessionFileName, self.sessionStatusFileName)
@@ -393,8 +396,11 @@ func stackStepOut(caller string, callerNameEntry string, env *core.Env) {
 		if stack == callerNameEntry {
 			stack = ""
 		} else {
-			panic(fmt.Errorf("stack string not match when stepping out from '%s', stack: '%s'",
-				caller, stack))
+			fields := strings.Split(stack, sep)
+			if len(fields) != 1 || fields[0] != caller {
+				panic(fmt.Errorf("stack string not match when stepping out from '%s', stack: '%s'",
+					sep+caller, stack))
+			}
 		}
 	} else {
 		stack = stack[0 : len(stack)-len(sep)-len(caller)]
diff --git a/pkg/cli/execute/interactive.go b/pkg/cli/execute/interactive.go
index c9a2ae8..5c0d464 100644
--- a/pkg/cli/execute/interactive.go
+++ b/pkg/cli/execute/interactive.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/pingcap/ticat/pkg/builtin"
 	"github.com/pingcap/ticat/pkg/cli/core"
 	"github.com/pingcap/ticat/pkg/cli/display"
 )
@@ -46,7 +47,7 @@ func tryDelayAndStepByStepAndBreakBefore(cc *core.Cli, env *core.Env, cmd core.P
 }
 
 func tryStepByStepAndBreakBefore(cc *core.Cli, env *core.Env, cmd core.ParsedCmd, breakByPrev bool) BreakPointAction {
-	atBegin := cc.BreakPoints.AtBegin()
+	atBegin := cc.BreakPoints.BreakAtBegin()
 	stepByStep := env.GetBool("sys.step-by-step")
 	stepIn := env.GetBool("sys.breakpoint.status.step-in")
 	stepOut := env.GetBool("sys.breakpoint.status.step-out")
@@ -115,13 +116,30 @@ func tryBreakAfter(cc *core.Cli, env *core.Env, cmd core.ParsedCmd) BreakPointAc
 	reason := display.ColorTip("break-point: after command ", env) + display.ColorCmd("["+name+"]", env)
 	return readUserBPAChoice(
 		reason,
-		[]string{"c", "q"},
+		[]string{"c", "i", "q"},
 		getAllBPAs(),
 		true,
 		cc,
 		env)
 }
 
+func tryBreakAtEnd(cc *core.Cli, env *core.Env) {
+	if !cc.BreakPoints.BreakAtEnd() {
+		return
+	}
+	reason := display.ColorTip("break-point: at main-thread end", env)
+	bpa := readUserBPAChoice(
+		reason,
+		[]string{"c", "i", "q"},
+		getAllBPAs(),
+		true,
+		cc,
+		env)
+	if bpa != BPAContinue {
+		panic(fmt.Errorf("[tryBreakAtEnd] should never happen"))
+	}
+}
+
 func tryDelay(cc *core.Cli, env *core.Env, delayKey string) {
 	delaySec := env.GetInt(delayKey)
 	if delaySec > 0 {
@@ -171,7 +189,8 @@ func readUserBPAChoice(reason string, choices []string, actions BPAs, lowerInput
 			if action == BPAQuit {
 				panic(core.NewAbortByUserErr())
 			} else if action == BPAInteract {
-				interactiveMode(cc, env, "e")
+				cc.Screen.Print("\n")
+				builtin.InteractiveMode(cc, env, "e")
 				if env.GetBool("sys.interact.leaving") {
 					env.GetLayer(core.EnvLayerSession).Delete("sys.interact.leaving")
 					return BPAContinue
@@ -186,39 +205,6 @@ func readUserBPAChoice(reason string, choices []string, actions BPAs, lowerInput
 	}
 }
 
-func interactiveMode(cc *core.Cli, env *core.Env, exitStr string) {
-	sessionEnv := env.GetLayer(core.EnvLayerSession)
-	sessionEnv.SetBool("sys.interact.inside", true)
-
-	cc = cc.CopyForInteract()
-	buf := bufio.NewReader(os.Stdin)
-	for {
-		if env.GetBool("sys.interact.leaving") {
-			break
-		}
-		selfName := env.GetRaw("strs.self-name")
-		cc.Screen.Print("\n" + display.ColorExplain("", env) + display.ColorWarn(exitStr, env) + ":" +
-			//display.ColorExplain(" exit interactive mode\n", env))
-			" exit interactive mode\n")
-
-		cc.Screen.Print(display.ColorTip(selfName+"> ", env))
-		lineBytes, err := buf.ReadBytes('\n')
-		if err != nil {
-			panic(fmt.Errorf("[readFromStdin] read from stdin failed: %v", err))
-		}
-		if len(lineBytes) == 0 {
-			continue
-		}
-		line := strings.TrimSpace(string(lineBytes))
-		if line == exitStr {
-			break
-		}
-		cc.Executor.Execute("(interact)", cc, env, nil, strings.Fields(line)...)
-	}
-
-	sessionEnv.GetLayer(core.EnvLayerSession).Delete("sys.interact.inside")
-}
-
 func getAllBPAs() BPAs {
 	return BPAs{
 		"c": BPAContinue,