Purpose

A short-circuit hook. Fired early in MAM_Phone_Data_Pipeline::phase_settings(). If any subscriber returns a non-empty array, the pipeline returns that payload immediately and skips every later phase (no mam_get_phone_data_before_send, no button loop, no home_cats, no phase_finalize cleanup).

Use it when a use-case plugin needs to fully replace the response — bypassing every other subscriber.

⚠️ Frozen contract. No active subscribers in the wild today, but the contract remains because a future use-case plugin might need it.

Signature

$payload = apply_filters( 'mam_local_app_data', array() );

Returns: array — empty array (continue normal pipeline) or a fully-formed phone-data response (short-circuit).

When to use

Almost never. The standard extension point is mam_get_phone_data_before_send at the appropriate priority.

The short-circuit is for cases where:

• A use-case plugin needs to serve a totally different response shape (not augmented — replaced)
• Maintenance mode / outage banner needs to bypass normal logic
• A custom auth flow needs to redirect before the normal pipeline runs

Example: maintenance mode override

add_filter( 'mam_local_app_data', function ( $data ) {

    $maintenance_until = get_option( 'mam_maintenance_until', 0 );

    if ( $maintenance_until <= time() ) {
        return $data;   // empty array — let the normal pipeline run
    }

    // Return a minimal maintenance payload — bypasses everything below.
    return array(
        'maintenance_mode' => true,
        'message'          => 'We'll be back at ' . date( 'g:ia', $maintenance_until ),
        'retry_after_ts'   => $maintenance_until,
    );
}, 10 );

Gotchas

• The empty-array contract is binding. Returning null or false is interpreted as “skip my override” (same as empty array).
• Returning a non-empty array bypasses output shaping. mam_replace_null_with_empty_string(), JSON validation, and the cursor mechanism don’t run. You’re fully responsible for a JSON-safe response.
• Subscribers don’t compose. First non-empty return wins; later subscribers’ values are not merged.
• Never use this for “augment the response.” That’s mam_get_phone_data_before_send. The short-circuit hook is for full replacement only.
• The mobile client may not handle a degenerate response gracefully. If you short-circuit with an unrecognized shape, the app may crash. Test with the Previewer first.

Related articles

• Phone data pipeline overview
• Phone data pipeline phases
• Hook: mam_get_phone_data_before_send
• Frozen public contracts reference

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