Add session restore support by cheerfulScumbag · Pull Request #800 · mangowm/mango

cheerfulScumbag · 2026-03-22T22:38:47Z

Adds opt-in session save/restore support to Mango.

When session_restore=1:

Mango saves a restorable snapshot on clean shutdown
Mango loads that snapshot on next startup
Mango relaunches supported apps from persisted launch_command
Mango restores tag, monitor, floating/fullscreen state, and floating geometry as windows map

When session_restore=0:

Mango behaves as before
no session file is written
no restore or relaunch path runs

Supported config:
'session_restore=0|1'

Optional override config:
'session_launch=app_id|command'
'session_launch=app_id|title|command'

Current launch-command priority:

exact command Mango itself used to spawn the app
normalized higher-level launcher command recovered from process metadata
raw process argv fallback
title-specific session_launch
app-only session_launch
plain app_id

Normalization currently implemented:

Flatpak apps normalize to desktop-entry launcher command
desktop-entry-backed apps normalize to the desktop file Exec= command

Validated:

disabled path writes no session file
clean shutdown save
self-relaunch on next Mango startup
duplicate foot windows with title-specific mappings
exact command capture for Mango-owned exec-once launches
process-based recovery for apps Mango did not spawn directly
single-monitor restore
floating geometry restore
tag restore
two-monitor restore when outputs already exist before clients map

cheerfulScumbag · 2026-03-22T23:20:12Z

current implementation works, but I want to improve automatic launch recovery so common apps do not require as much manual session_launch configuration

cheerfulScumbag · 2026-03-23T17:03:43Z

Updated this draft with a stronger automatic launch-command recovery path.

Since the original draft, Mango now:

tracks exact commands for apps it launches itself
recovers commands from client process metadata for apps it did not launch directly
normalizes Flatpak apps to desktop-entry launcher command
normalizes desktop-entry-backed apps to the desktop file Exec= command

That reduces the need for manual session_launch rules for common apps.

cheerfulScumbag · 2026-03-24T21:57:41Z

tested on multiple programs and they all restore with no issues
so when session_restore=1:

Mango saves a restorable snapshot on clean shutdown
Mango loads that snapshot on next startup
Mango relaunches supported apps from persisted launch_command
Mango restores tag, monitor, floating/fullscreen state, and floating geometry as windows map

Give it a test and let me know what you think

cheerfulScumbag · 2026-04-04T12:56:50Z

Small follow-up: I have been using this for a while now with no bugs i can find, multi-monitor restore works fine.

I also tightened the branch since the original draft with portable desktop-entry lookup, improved launcher recovery, and a trusted session-file check.

@DreamMaoMao whenever you have time, I’d appreciate any feedback on this.

DreamMaoMao · 2026-04-05T04:18:37Z

I'm still not sure if I want to add this feature.

cheerfulScumbag · 2026-04-05T10:57:00Z

Thanks for the reply.

Understood. To help me judge whether this is worth pressing further, can i ask what your hesitation mainly about?

I’m happy to reduce scope further if needed, but if the concern is that session restore itself is out of scope for Mango, that’s also useful for me to know.

Wateir · 2026-04-22T21:57:39Z

+	session_save_now(true);
+	session_shutdown();


Maybe i'm wrong on this, but from my understanding this two function gonna be call for everyone and not only the one who have session restore on the config

This is intentional. The session hooks are always called from the compositor lifecycle, but the feature gate is inside the session module.

Wateir · 2026-04-22T22:04:08Z

+void mango_session_spawn_tracker_init(void);
+void mango_session_spawn_tracker_shutdown(void);
+void mango_session_track_spawned_command(pid_t pid, const char *command);
+void mango_session_attach_spawn_command(Client *c);
+void mango_session_remember_client_launch_command(Client *c,
+												  const char *command);
+static char *mango_session_recover_process_command(pid_t pid);
+static void mango_session_attach_process_command(Client *c);
+static char *mango_session_find_desktop_exec(const char *app_id);
+static char *mango_session_find_flatpak_command(const char *app_id);
+static char *mango_session_normalize_launch_command(Client *c, pid_t pid);


WHAT THE FUCK DO I WROTE ?

Sorry, idk why i'm thinking function declaration was global constant ....

Wateir · 2026-04-22T21:59:47Z

+	struct wl_list link;
+	pid_t pid;
+	time_t created_at;
+	char command[1024];


The 1024 here seems a magic number

Good point. I’ll replace those with named constants so the limits are defined in one place instead of repeating raw buffer sizes.

Wateir · 2026-04-22T22:00:30Z

+	char title[512];
+	char monitor[128];
+	char launch_command[1024];
+	int32_t pid;


Magic number here

Wateir · 2026-04-22T22:04:08Z

+void mango_session_spawn_tracker_init(void);
+void mango_session_spawn_tracker_shutdown(void);
+void mango_session_track_spawned_command(pid_t pid, const char *command);
+void mango_session_attach_spawn_command(Client *c);
+void mango_session_remember_client_launch_command(Client *c,
+												  const char *command);
+static char *mango_session_recover_process_command(pid_t pid);
+static void mango_session_attach_process_command(Client *c);
+static char *mango_session_find_desktop_exec(const char *app_id);
+static char *mango_session_find_flatpak_command(const char *app_id);
+static char *mango_session_normalize_launch_command(Client *c, pid_t pid);


WHAT THE FUCK DO I WROTE ?

Sorry, idk why i'm thinking function declaration was global constant ....

cheerfulScumbag marked this pull request as draft March 22, 2026 23:16

DreamMaoMao force-pushed the main branch from 17ff2ad to 064bcad Compare March 23, 2026 02:56

cheerfulScumbag marked this pull request as ready for review March 23, 2026 17:03

cheerfulScumbag marked this pull request as draft March 23, 2026 17:19

cheerfulScumbag marked this pull request as ready for review March 23, 2026 19:15

cheerfulScumbag force-pushed the feature/session-restore branch from e87731f to 3aa9a90 Compare March 24, 2026 20:19

cheerfulScumbag force-pushed the feature/session-restore branch from 3aa9a90 to f78d3b9 Compare March 25, 2026 20:43

cheerfulScumbag changed the title ~~Add opt-in session save and restore support~~ Restore Window Sessions Mar 26, 2026

cheerfulScumbag changed the title ~~Restore Window Sessions~~ Add session restore support Mar 26, 2026

DreamMaoMao force-pushed the main branch 2 times, most recently from 0d3ed31 to 5267649 Compare March 30, 2026 10:35

cheerfulScumbag added 4 commits April 6, 2026 09:16

Add opt-in session save and restore support

44b761d

Improve automatic session launch command recovery#

818f80c

Harden session launch command recovery

e2b63a0

remove dead helper

f86ec68

cheerfulScumbag force-pushed the feature/session-restore branch from f78d3b9 to f86ec68 Compare April 6, 2026 08:20

DreamMaoMao force-pushed the main branch from 736d801 to 461dcb6 Compare April 21, 2026 09:45

Wateir reviewed Apr 22, 2026

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