feat: add leave_hook symmetric to enter_hook

[tyvsmith]

Summary

Mirrors the existing enter_hook mechanism with a leave_hook that fires when capture for a client is released.

Motivation: external scripts that change host state on cross (e.g. swapping keyboard layout, toggling natural scroll, repositioning windows) currently have no symmetric "you're back" signal — enter_hook fires deterministically but the only way to detect release today is to poll hyprctl cursorpos / similar, which is fragile because the local cursor isn't actually pinned during capture on Wayland.

Design

A single new IPC capture event ICaptureEvent::ClientLeft(handle) emitted from release_capture() in src/capture.rs. Every release path funnels through that function:

• release_bind chord
• peer Leave event over the wire
• CaptureRequest::Destroy when the active client is being torn down (with an explicit note about hostname-change client recreation)
• CaptureRequest::Release

Wiring otherwise exactly mirrors enter_hook:

Layer	enter_hook	leave_hook
src/config.rs	enter_hook: Option<String>	+ leave_hook: Option<String>
lan-mouse-ipc/src/lib.rs	enter_cmd on ClientConfig, UpdateEnterHook request	+ leave_cmd, UpdateLeaveHook
src/client.rs	set_enter_hook / get_enter_cmd	+ set_leave_hook / get_leave_cmd
src/service.rs	update_enter_hook, spawn_hook_command, dispatch on ClientEntered	+ update_leave_hook, spawn_leave_hook_command, dispatch on ClientLeft
lan-mouse-cli/src/lib.rs	--enter-hook flag on add-client	+ --leave-hook flag

Docs

The existing enter_hook has been undocumented since #130. Second commit backfills both in the example config.toml so the per-client hook surface is discoverable.

Out of scope

• GUI surface in lan-mouse-gtk for the new field (text-config only for now)
• Unit tests (no test infrastructure exists in the project today; manual smoke-tested with notify-send hooks across crossing + release_bind release on Wayland/Hyprland)

Test plan

• Builds clean: cargo build --release (1m 20s, no warnings)
• cargo clippy --all-targets --release -- -D warnings clean
• Manual smoke: enter_hook and leave_hook set to notify-send strings, daemon restarted from built binary, cross to client and release via chord — both notifications fire as expected
• Verify behavior with peer-initiated Leave (cross-back from the remote side)
• Verify behavior on cli deactivate of the active client

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds support for per-client “leave hooks” that run when capture is released for a client, wiring the new setting through config, IPC, CLI, and capture/service event handling.

Changes:

• Introduce leave_hook / leave_cmd in config and IPC models, plus CLI flag support.
• Emit a new ICaptureEvent::ClientLeft on release paths and handle it in the service.
• Execute configured leave commands via sh -c when a client is left.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/service.rs	Handle UpdateLeaveHook, persist leave_hook, and spawn leave-hook commands on ClientLeft.
src/config.rs	Add leave_hook to TOML and runtime config conversion paths.
src/client.rs	Store and expose per-client leave_cmd in ClientManager.
src/capture.rs	Add ClientLeft event and ensure release paths trigger it.
lan-mouse-ipc/src/lib.rs	Extend IPC structs/enums with leave-hook fields and requests.
lan-mouse-cli/src/lib.rs	Add --leave-hook flag and send UpdateLeaveHook on create.
config.toml	Document and example-configure leave_hook.

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[tyvsmith]

Reference implementation for hook driven input changes

Add to ~/.config/lan-mouse/config.toml

enter_hook = "lan-mouse-mode mac"
leave_hook = "lan-mouse-mode default"

Script that swaps super/alt & inverts scrolling for Hyprland host and MacOS client

[feschber]

Would you mind removing 2804351 from this PR in favor of #449 ?

[tyvsmith]

Would you mind removing 2804351 from this PR in favor of #449 ?

Sure, it's just here for now to make CI run until we land the other. I've reparented this one on top of #449, so will need to land that first, but then will merge cleanly as is..

[tyvsmith]

Should be good to merge at your leisure now that #449 is landed.