fix: replace tmux pattern matching with session file detection for kanban workspace status

fix: replace tmux pattern matching with session file detection for kanban workspace status

Author: marcus

internal/plugins/workspace/agent.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"log/slog"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -743,7 +744,8 @@ func (p *Plugin) scheduleInteractivePoll(worktreeName string, delay time.Duratio
 // AgentPollUnchangedMsg signals content unchanged, schedule next poll.
 type AgentPollUnchangedMsg struct {
 	WorkspaceName  string
-	CurrentStatus WorktreeStatus // For adaptive polling interval selection
+	CurrentStatus WorktreeStatus // Status including session file re-check
+	WaitingFor    string         // Prompt text if waiting
 	// Cursor position captured atomically (even when content unchanged)
 	CursorRow     int
 	CursorCol     int
@@ -845,41 +847,58 @@ func (p *Plugin) handlePollAgent(worktreeName string) tea.Cmd {
 		output = trimCapturedOutput(output, maxBytes)
 
 		// Use hash-based change detection to skip processing if content unchanged
-		if outputBuf != nil && !outputBuf.Update(output) {
-			// Content unchanged - signal to schedule next poll with delay
-			// Still include cursor position since cursor can move without content changing
-			return AgentPollUnchangedMsg{
-				WorkspaceName:  worktreeName,
-				CurrentStatus: currentStatus,
-				CursorRow:     cursorRow,
-				CursorCol:     cursorCol,
-				CursorVisible: cursorVisible,
-				HasCursor:     hasCursor,
-				PaneHeight:    paneHeight,
-				PaneWidth:     paneWidth,
-			}
-		}
+		outputChanged := outputBuf == nil || outputBuf.Update(output)
 
-		// Content changed - detect status (skip during interactive mode to reduce I/O, td-f29f2d)
+		// Detect status. Both detectors run; each is authoritative for what it's good at (td-2fca7d):
+		//   - tmux patterns: thinking, done, error (high-signal, session files can't detect these)
+		//   - session files: active vs waiting (reliable, tmux patterns are noisy for this)
+		// Session file detection ALWAYS runs (even when output unchanged) because the agent
+		// may finish while tmux output stays the same (td-2fca7d v8).
 		status := currentStatus
 		waitingFor := ""
 		if !interactiveCapture {
-			status = detectStatus(output)
-			if status == StatusWaiting {
-				waitingFor = extractPrompt(output)
+			if outputChanged {
+				// Tmux pattern detection only when output changes (same output = same patterns).
+				status = detectStatus(output)
+				if status == StatusWaiting {
+					waitingFor = extractPrompt(output)
+				}
 			}
-			// For supported agents: supplement tmux detection with session file analysis
-			// Session files are more reliable for detecting "waiting at prompt" state
-			if status == StatusActive {
+			// Session file check runs every poll — mtime changes independently of tmux output.
+			// Only override active/waiting; preserve tmux-detected thinking/done/error.
+			if status == StatusActive || status == StatusWaiting {
 				if sessionStatus, ok := detectAgentSessionStatus(agentType, wtPath); ok {
-					if sessionStatus == StatusWaiting {
-						status = StatusWaiting
-						waitingFor = "Waiting for input"
+					prevStatus := status
+					status = sessionStatus
+					if status == StatusWaiting {
+						waitingFor = extractPrompt(output)
+						if waitingFor == "" {
+							waitingFor = "Waiting for input"
+						}
+					} else {
+						waitingFor = ""
 					}
+					slog.Debug("status: session file override", "worktree", worktreeName, "prev", prevStatus, "session", sessionStatus)
+				} else {
+					slog.Debug("status: no session file, using tmux", "worktree", worktreeName, "status", status, "agent", agentType)
 				}
 			}
 		}
 
+		if !outputChanged {
+			return AgentPollUnchangedMsg{
+				WorkspaceName:  worktreeName,
+				CurrentStatus: status,
+				WaitingFor:    waitingFor,
+				CursorRow:     cursorRow,
+				CursorCol:     cursorCol,
+				CursorVisible: cursorVisible,
+				HasCursor:     hasCursor,
+				PaneHeight:    paneHeight,
+				PaneWidth:     paneWidth,
+			}
+		}
+
 		return AgentOutputMsg{
 			WorkspaceName:  worktreeName,
 			Output:        output,
@@ -1068,31 +1087,34 @@ func tailUTF8Safe(s string, n int) string {
 }
 
 // detectStatus determines agent status from captured output.
-// Optimized to avoid unnecessary string allocations.
+// This is the tmux-based fallback for agents without session file support (td-2fca7d).
+// For supported agents (Claude, Codex, Gemini, OpenCode), session file analysis runs
+// first in handlePollAgent and is more reliable than tmux pattern matching.
 func detectStatus(output string) WorktreeStatus {
 	// Check tail of output for status patterns (avoids splitting entire string)
 	checkText := tailUTF8Safe(output, statusCheckBytes)
 	textLower := strings.ToLower(checkText)
 
-	// Waiting patterns (agent needs user input) - highest priority
-	// Check before thinking since waiting blocks progress
+	// Waiting patterns — only check the last few lines of output (td-2fca7d).
+	// A prompt is only relevant if it's at the bottom of the screen (the agent is
+	// actually waiting right now). Checking 2048 bytes of scrollback history caused
+	// false positives from old prompts and shell prompt characters like "❯".
 	waitingPatterns := []string{
 		"[y/n]",       // Claude Code permission prompt
 		"(y/n)",       // Aider style
 		"allow edit",  // Claude Code file edit
 		"allow bash",  // Claude Code bash command
-		"waiting for", // Generic waiting
 		"press enter", // Continue prompt
 		"continue?",
 		"approve",
 		"confirm",
 		"do you want", // Common prompt
-		"❯",           // Claude Code input prompt (waiting for user)
-		"╰─❯",         // Claude Code prompt with tree line decoration
 	}
 
+	lastLines := extractLastNLines(checkText, 5)
+	lastLinesLower := strings.ToLower(lastLines)
 	for _, pattern := range waitingPatterns {
-		if strings.Contains(textLower, pattern) {
+		if strings.Contains(lastLinesLower, pattern) {
 			return StatusWaiting
 		}
 	}
@@ -1156,6 +1178,34 @@ func detectStatus(output string) WorktreeStatus {
 	return StatusActive
 }
 
+// extractLastNLines returns the last n non-empty lines of text.
+// Used by detectStatus to restrict waiting pattern matching to the bottom of the terminal.
+func extractLastNLines(text string, n int) string {
+	// Work backwards from the end to find the last n lines
+	end := len(text)
+	// Skip trailing whitespace/newlines
+	for end > 0 && (text[end-1] == '\n' || text[end-1] == '\r' || text[end-1] == ' ') {
+		end--
+	}
+	if end == 0 {
+		return ""
+	}
+
+	linesFound := 0
+	pos := end
+	for pos > 0 && linesFound < n {
+		pos--
+		if text[pos] == '\n' {
+			linesFound++
+		}
+	}
+	// If we stopped at a newline, skip past it
+	if pos > 0 || (pos == 0 && text[0] == '\n') {
+		pos++
+	}
+	return text[pos:end]
+}
+
 // extractPrompt finds the prompt text from output.
 // Optimized to search backwards without splitting the entire string.
 func extractPrompt(output string) string {