coexistence: fix protocol switch back to Zigbee

[edmont]

A bus fault in the openthread thread was triggered when InitThreadStack() auto-started the radio stack while Zigbee still owned the 802.15.4 radio. Disable CHIP_DEVICE_CONFIG_ENABLE_THREAD_AUTOSTART via a CMake compile definition so OpenThread never starts autonomously; the coexistence runtime starts Thread explicitly once the radio dispatcher is handed over.

On the Matter→Zigbee switch, kill ZBOSS only after sending a clean NWK Leave so the coordinator removes the device's unique TCLK entry. This prevents the fresh-join TCLK mismatch that caused the coordinator to fail the Transport-Key delivery after the next reboot.

[github-actions]

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[Copilot]

Pull request overview

This PR hardens the Zigbee↔Matter coexistence runtime to prevent OpenThread from starting while Zigbee owns the 802.15.4 radio, and improves the Matter→Zigbee→Matter switch path by ensuring a clean Zigbee NWK Leave before tearing down ZBOSS (to avoid TCLK mismatch on re-join).

Changes:

• Disables OpenThread autostart at build time and adds explicit “start Thread if commissioned” logic after radio handover.
• Adds pre-/post-Matter-server-init hooks to safely switch the 802.15.4 callbacks dispatcher during InitThreadStack() / StartServer().
• Defers Matter switch until ZBOSS sends a NWK Leave, wiring the leave completion signal through the sample.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
subsys/lib/zigbee_matter_coexistence/Kconfig	Updates help text to reflect new signaling path.
subsys/lib/zigbee_matter_coexistence/coexistence.cpp	Adds dispatcher handover hooks, explicit Thread start, and Zigbee leave gating before switch.
subsys/lib/zigbee_matter_coexistence/CMakeLists.txt	Forces CHIP_DEVICE_CONFIG_ENABLE_THREAD_AUTOSTART=0 for coexistence builds.
samples/light_switch/src/app_task_zigbee.c	Forwards ZBOSS leave completion to coexistence runtime.
samples/light_switch/src/app_task_matter.cpp	Integrates new pre-/post-server-init coexistence hooks.
samples/light_bulb/src/app_task_matter.cpp	Integrates new pre-/post-server-init coexistence hooks.
include/zigbee/matter_coexistence.h	Updates/extends public coexistence API for new integration flow and leave signaling.
docs/includes/matter_extension_protocol_switch.txt	Documents new integration call sites and behavior.

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[edmont]

Addressed Copilot comments.

[ArekBalysNordic]

Added some comments to improve semaphors in coexistence.

I think we should do a similar thing for app_task_zigbee in the light bulb.
For example in the line 594 as:

#ifdef CONFIG_ZIGBEE_MATTER_COEXISTENCE
  if (bufid) {
    zb_zdo_app_signal_hdr_t *sig_handler = nullptr;
    zb_zdo_app_signal_type_t sig = zb_get_app_signal(bufid, &sig_handler);
    if (sig == ZB_ZDO_SIGNAL_LEAVE &&
        ZB_ZDO_APP_SIGNAL_STATUS(sig_handler) == RET_OK) {
      zb_zdo_signal_leave_params_t *leave_params =
          ZB_ZDO_SIGNAL_GET_PARAMS(sig_handler, zb_zdo_signal_leave_params_t);
      if (leave_params->leave_type == ZB_NWK_LEAVE_TYPE_RESET) {
        /* Unblock a pending Matter switch deferred until Leave completes. */
        zigbee_matter_coexistence_on_zboss_leave_signal();
      }
    }
  }
#endif
  ZB_ERROR_CHECK(zigbee_default_signal_handler(bufid));
``

To reflect the same case as for light switch.

[annwoj]

one minor suggestion

[edmont]

I think we should do a similar thing for app_task_zigbee in the light bulb.

I've moved the checks to the coex module. See coexistence: centralize ZBOSS leave signal handling commit.