fix: add AnsPress compatibility guard for wu-ajax product search (issue #171)

[superdav42]

Summary

• Adds WP_Ultimo\Compat\AnsPress_Compat — a new compatibility class that prevents AnsPress from intercepting Ultimate Multisite's Light Ajax requests and causing a fatal error when selecting a product to add to a membership.
• Registers the compat class in class-wp-ultimo.php alongside the other compat layers.
• Updates the known-incompatibilities wiki page to document that this conflict is now automatically resolved (no manual action required).

Root cause

AnsPress registers an AJAX dispatcher on the WordPress init hook (AP_Ajax::init() in v4.x, anspress_ajax() in older versions) that calls die() after processing any request it recognises.

Ultimate Multisite's Light Ajax system also fires on init (when wu-when=init) and relies on reaching its own wu_ajax_* action hooks without interference. When both plugins are active, AnsPress's handler runs first and terminates the request before Ultimate Multisite can serve the product-search JSON, producing a fatal/empty-response error in the membership product-selection modal.

Fix

The compat class hooks into plugins_loaded at PHP_INT_MAX (after AnsPress has registered its own hooks) and removes AnsPress's init-time AJAX handlers before they can fire. The guard is a no-op when AnsPress is not active — no performance impact for sites that don't use AnsPress.

Covers both:

• AnsPress 4.x — class-based AP_Ajax::init() registered on init at priorities 1, 2, and 10
• AnsPress < 4.x — function-based anspress_ajax() registered on init

Testing

1. Install and activate AnsPress alongside Ultimate Multisite.
2. Navigate to Network Admin → Memberships → Edit any membership.
3. Click "Add Product" — the product search modal should open and the selectize search should return results without a fatal error.
4. Confirm the product can be added successfully.

Without this fix, step 3 produces a fatal error / empty AJAX response.

Closes #171

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Resolved incompatibility with AnsPress – Question and Answer plugin that could trigger fatal errors when selecting products for membership creation.
  • Ultimate Multisite 2.4.3+ includes an automatic compatibility fix that seamlessly resolves conflicts without requiring manual user intervention.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 6cbad448-7d25-485e-a3e3-609f2bb40c80

📥 Commits

Reviewing files that changed from the base of the PR and between 922d85c and adc26d5.

📒 Files selected for processing (3)

• .wiki/known-incompatibilities-with-other-plugins.md
• inc/class-wp-ultimo.php
• inc/compat/class-anspress-compat.php

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📝 Walkthrough

Walkthrough

The changes add a compatibility layer for the AnsPress plugin that detects and removes conflicting AJAX dispatcher hooks during Ultimate Multisite AJAX requests, preventing fatal errors when selecting products for membership creation. A new compatibility class is initialized in the main boot sequence, with documentation updated to reflect the automatic fix.

Changes

Cohort / File(s)	Summary
Documentation .wiki/known-incompatibilities-with-other-plugins.md	Added incompatibility entry for AnsPress plugin, documenting the AJAX dispatcher conflict on the init hook and noting the automatic fix included in version 2.4.3+.
Compatibility Integration inc/class-wp-ultimo.php	Integrated AnsPress_Compat::get_instance() call into the main compatibility boot sequence alongside existing plugin compatibility handlers.
AnsPress Compatibility Implementation inc/compat/class-anspress-compat.php	New Singleton compatibility class that removes AnsPress AJAX dispatcher hooks during wu-ajax requests, with helper method to safely remove hooks by class and method name.

Sequence Diagram

sequenceDiagram
    participant Client as Ultimate Multisite Request
    participant PL as plugins_loaded Hook
    participant Init as init Hook
    participant AP as AnsPress
    participant AJAX as AJAX Handler
    
    Client->>PL: Fire plugins_loaded
    PL->>PL: Check if AnsPress exists<br/>(AP_Ajax or anspress_ajax())
    Init->>Init: Check if wu-ajax request
    alt wu-ajax request detected
        Init->>AP: Remove AnsPress AJAX hooks<br/>(AP_Ajax::init)
        AP-->>Init: Hooks removed
    else Not wu-ajax request
        Init->>AP: AnsPress hooks remain active
    end
    Client->>AJAX: Process request
    AJAX-->>Client: Response

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Poem

🐰 A question of hooks, a answer we found,
AnsPress and Ajax were tangled around,
With careful precision we untie the thread,
So memberships flourish, no errors to dread! 🌸

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch bugfix/anspress-ajax-compatibility

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[github-actions]

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