From ef79fbe5add01e22b75e6453fa8af423bede49d4 Mon Sep 17 00:00:00 2001
From: Vitali <gottselig.v@gmail.com>
Date: Sun, 26 Jul 2026 13:27:16 +0000
Subject: [PATCH] Persist the printer token on connect (survive unclean
 restarts)

The token obtained from the printer was only written to the known-hosts
file by the shutdown defer in main(), which runs only on a graceful exit.
On an unclean exit (SIGKILL, container restart, OOM, power loss) a freshly
authorized token was therefore lost, forcing another touchscreen
authorization on the next start.

Additionally, the IP-only fallback printer (-host <ip> without discovery)
was created without an ID, and LocalStorage.Add skips ID-less printers, so
its token was never persisted even on a clean exit.

Fix:
- Add an OnPrinterUpdate hook, invoked right after a successful connect,
  which main() wires to ls.Add(printer) + ls.Save() -- persisting the
  (refreshed) token immediately instead of only at shutdown.
- Give the IP-only fallback printer an ID (its host) so ls.Add persists it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018zWUoJhzouLTnkrpZE7rkJ
---
 connector.go | 10 ++++++++++
 main.go      | 15 +++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/connector.go b/connector.go
index 311a458..cb8fbfb 100644
--- a/connector.go
+++ b/connector.go
@@ -18,6 +18,10 @@ var (
 	errFileTooLarge = errors.New("File is too large.")
 )
 
+// OnPrinterUpdate, if set, is called after a successful connect so the caller
+// can persist the printer's (refreshed) token to disk. Set by main().
+var OnPrinterUpdate func(*Printer)
+
 type Payload struct {
 	File      io.Reader
 	Name      string
@@ -126,6 +130,12 @@ func (c *connector) Upload(printer *Printer, payload *Payload) error {
 			}
 			defer h.Disconnect()
 
+			// Persist the (possibly refreshed) token so it survives restarts,
+			// including an unclean exit that skips the shutdown defer.
+			if OnPrinterUpdate != nil {
+				OnPrinterUpdate(printer)
+			}
+
 			if payload.Size > FILE_SIZE_MAX {
 				return errFileTooLarge
 			}
diff --git a/main.go b/main.go
index 9278fe0..30b4ef0 100644
--- a/main.go
+++ b/main.go
@@ -83,6 +83,16 @@ func main() {
 
 	var printer *Printer
 	ls := NewLocalStorage(KnownHosts)
+	// Persist the token to known hosts as soon as it is (re)obtained on connect,
+	// so it survives restarts even on an unclean exit (the shutdown defer below
+	// only runs on a graceful exit).
+	OnPrinterUpdate = func(p *Printer) {
+		if p == nil {
+			return
+		}
+		ls.Add(p)
+		_ = ls.Save()
+	}
 	defer func() {
 		if printer != nil {
 			// update printer's token
@@ -140,8 +150,9 @@ func main() {
 				printer = printers[0]
 			}
 		} else {
-			// directly to printer using ip/hostname
-			printer = &Printer{IP: Host}
+			// directly to printer using ip/hostname; keep an ID so the token gets
+			// persisted (ls.Add skips ID-less printers)
+			printer = &Printer{IP: Host, ID: Host}
 		}
 	}