chore: release v0.21.3

internal/cat/log.go

@@ -4,6 +4,7 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"sync"
 )
 
 // LogSink, when set by the host app at startup, receives every CAT debug
@@ -15,13 +16,21 @@ var LogSink func(format string, args ...any)
 // catLogger forwards Printf either to the host LogSink (preferred) or to a
 // local file/stderr fallback. Keeps the call sites (debugLog.Printf(...))
 // unchanged.
-type catLogger struct{ fallback *log.Logger }
+type catLogger struct {
+	once     sync.Once
+	fallback *log.Logger
+}
 
 func (c *catLogger) Printf(format string, args ...any) {
 	if LogSink != nil {
 		LogSink("cat: "+format, args...)
 		return
 	}
+	// Only now, on a line that genuinely has nowhere else to go, is the fallback
+	// file opened. It used to be created at package init, so every installation
+	// grew an %APPDATA%\OpsLog\cat.log that nothing ever wrote to once the app
+	// wired LogSink — a decoy for anyone told to "check the CAT log".
+	c.once.Do(func() { c.fallback = openFallbackLog() })
 	if c.fallback != nil {
 		c.fallback.Printf(format, args...)
 	}
@@ -30,7 +39,7 @@ func (c *catLogger) Printf(format string, args ...any) {
 // debugLog writes CAT debug events so users can diagnose mode/freq mismatches
 // without rebuilding with a console. Once LogSink is set, lines flow into the
 // main opslog.log.
-var debugLog = &catLogger{fallback: openFallbackLog()}
+var debugLog = &catLogger{}
 
 func openFallbackLog() *log.Logger {
 	base, err := os.UserConfigDir()
@@ -49,9 +58,15 @@ func openFallbackLog() *log.Logger {
 	return log.New(f, "", log.LstdFlags|log.Lmicroseconds)
 }
 
-// DebugLogPath returns where the fallback cat.log lives, for surfacing in the
-// UI / docs. When LogSink is wired, CAT lines are in the main app log instead.
+// DebugLogPath returns where the fallback cat.log lives, or "" when CAT lines are
+// going to the app log instead — which is the normal case, and the answer callers
+// actually need. It previously returned the path unconditionally, so the one place
+// that displayed it sent operators to an empty file in %APPDATA% while their CAT
+// diagnostics sat in data\opslog.log.
 func DebugLogPath() string {
+	if LogSink != nil {
+		return "" // lines go to the unified app log; there is no separate cat.log
+	}
 	base, err := os.UserConfigDir()
 	if err != nil {
 		return ""