feat(termexec): enhance dynamic header (animation) handling for different agent types

Author: 35C4n0r

lib/httpapi/setup.go

@@ -32,6 +32,7 @@ func SetupProcess(ctx context.Context, config SetupProcessConfig) (*termexec.Pro
 		Args:           config.ProgramArgs,
 		TerminalWidth:  config.TerminalWidth,
 		TerminalHeight: config.TerminalHeight,
+		AgentType:      config.AgentType,
 	})
 	if err != nil {
 		logger.Error(fmt.Sprintf("Error starting process: %v", err))

lib/screentracker/conversation.go

@@ -145,24 +145,11 @@ func FindNewMessage(oldScreen, newScreen string, agentType msgfmt.AgentType) str
 	newLines := strings.Split(newScreen, "\n")
 	oldLinesMap := make(map[string]bool)
 
-	// -1 indicates no header
-	dynamicHeaderEnd := -1
-
-	// Skip header lines for Opencode agent type to avoid false positives
-	// The header contains dynamic content (token count, context percentage, cost)
-	// that changes between screens, causing line comparison mismatches:
-	//
-	// ┃  # Getting Started with Claude CLI                                   ┃
-	// ┃  /share to create a shareable link                 12.6K/6% ($0.05)  ┃
-	if len(newLines) >= 2 && agentType == msgfmt.AgentTypeOpencode {
-		dynamicHeaderEnd = 2
-	}
-
 	for _, line := range oldLines {
 		oldLinesMap[line] = true
 	}
 	firstNonMatchingLine := len(newLines)
-	for i, line := range newLines[dynamicHeaderEnd+1:] {
+	for i, line := range newLines {
 		if !oldLinesMap[line] {
 			firstNonMatchingLine = i
 			break

lib/termexec/termexec.go

@@ -13,22 +13,26 @@ import (
 
 	"github.com/ActiveState/termtest/xpty"
 	"github.com/coder/agentapi/lib/logctx"
+	"github.com/coder/agentapi/lib/msgfmt"
 	"github.com/coder/agentapi/lib/util"
 	"golang.org/x/xerrors"
 )
 
 type Process struct {
-	xp               *xpty.Xpty
-	execCmd          *exec.Cmd
-	screenUpdateLock sync.RWMutex
-	lastScreenUpdate time.Time
+	xp                 *xpty.Xpty
+	execCmd            *exec.Cmd
+	screenUpdateLock   sync.RWMutex
+	lastScreenUpdate   time.Time
+	checkDynamicHeader bool
+	agentType          msgfmt.AgentType
 }
 
 type StartProcessConfig struct {
 	Program        string
 	Args           []string
 	TerminalWidth  uint16
 	TerminalHeight uint16
+	AgentType      msgfmt.AgentType
 }
 
 func StartProcess(ctx context.Context, args StartProcessConfig) (*Process, error) {
@@ -46,7 +50,7 @@ func StartProcess(ctx context.Context, args StartProcessConfig) (*Process, error
 		return nil, err
 	}
 
-	process := &Process{xp: xp, execCmd: execCmd}
+	process := &Process{xp: xp, execCmd: execCmd, checkDynamicHeader: true, agentType: args.AgentType}
 
 	go func() {
 		// HACK: Working around xpty concurrency limitations
@@ -112,17 +116,24 @@ func (p *Process) Signal(sig os.Signal) error {
 // result in a malformed agent message being returned to the
 // user.
 func (p *Process) ReadScreen() string {
+	var state string
 	for range 3 {
 		p.screenUpdateLock.RLock()
 		if time.Since(p.lastScreenUpdate) >= 16*time.Millisecond {
-			state := p.xp.State.String()
+			state = p.xp.State.String()
 			p.screenUpdateLock.RUnlock()
+			if p.checkDynamicHeader {
+				state, p.checkDynamicHeader = removeDynamicHeader(state, p.agentType)
+			}
 			return state
 		}
 		p.screenUpdateLock.RUnlock()
 		time.Sleep(16 * time.Millisecond)
 	}
-	return p.xp.State.String()
+	if p.checkDynamicHeader {
+		state, p.checkDynamicHeader = removeDynamicHeader(p.xp.State.String(), p.agentType)
+	}
+	return state
 }
 
 // Write sends input to the process via the pseudo terminal.

lib/termexec/utils.go

@@ -0,0 +1,59 @@
+package termexec
+
+import (
+	"strings"
+
+	"github.com/coder/agentapi/lib/msgfmt"
+)
+
+func calcAmpDynamicHeader(newLines []string) (int, bool) {
+	dynamicHeaderEnd := -1
+	firstTextEncountered := false
+	continueRemoving := true
+
+	// search for the first 3 consecutive empty lines after the first text encountered.
+	if len(newLines) > 3 {
+		for i := 0; i < len(newLines)-3; i++ {
+			if !firstTextEncountered && len(strings.Trim(newLines[i], " \n")) != 0 {
+				if strings.HasPrefix(strings.TrimSpace(newLines[i]), "┃") {
+					continueRemoving = false
+				}
+				firstTextEncountered = true
+			}
+			if firstTextEncountered && len(strings.Trim(newLines[i], " \n")) == 0 && len(strings.Trim(newLines[i+1], " \n")) == 0 &&
+				len(strings.Trim(newLines[i+2], " \n")) == 0 {
+				dynamicHeaderEnd = i
+				break
+
+			}
+		}
+	}
+	return dynamicHeaderEnd, continueRemoving
+}
+
+func calcOpencodeDynamicHeader(newLines []string) (int, bool) {
+	// Skip header lines for Opencode agent type to avoid false positives
+	// The header contains dynamic content (token count, context percentage, cost)
+	// that changes between screens, causing line comparison mismatches:
+	//
+	// ┃  # Getting Started with Claude CLI                                   ┃
+	// ┃  /share to create a shareable link                 12.6K/6% ($0.05)  ┃
+	if len(newLines) >= 2 {
+		return 2, true
+	}
+	return -1, true
+}
+
+func removeDynamicHeader(screen string, agentType msgfmt.AgentType) (string, bool) {
+	lines := strings.Split(screen, "\n")
+	dynamicHeaderEnd := -1
+	continueRemoving := true
+	if agentType == msgfmt.AgentTypeAmp {
+		dynamicHeaderEnd, continueRemoving = calcAmpDynamicHeader(lines)
+	} else if agentType == msgfmt.AgentTypeOpencode {
+		dynamicHeaderEnd, continueRemoving = calcOpencodeDynamicHeader(lines)
+	} else {
+		continueRemoving = false
+	}
+	return strings.Join(lines[dynamicHeaderEnd+1:], "\n"), continueRemoving
+}