PR Vision v0.2.0: admin/settings interface + correctness fixes

Requirements 1-8 + all non-negotiables:

1. Model manager (CRUD): PRV_Model_Registry, prv_models v2 option, versioned
   idempotent migration from v0.1.x flat-string format, Settings page CRUD.

2. Per-model run-health: PRV_Model_Registry::update_health() after each run;
   health badges (Healthy/Retired?/Disabled/Unknown) in model table + dashboard.

3. Metric comparability: PRV_Config_Version stamps every run with config_version;
   save-bar warning on scoring-relevant changes; orphaned rows excluded by version.

4. Projected cost at save: PRV_Config::get_projected_cost(); over-cap warning;
   prv_last_run_truncated option + visible notice when cap hit mid-run.

5. Config surface: peptide set, intents, cadence (reschedules cron), budget cap;
   all validated + sanitized; next-run timestamp shown.

6. API-key three-state: not-defined / defined-ok / defined-failed; derived from
   ledger; never displays the key.

7. Run-lock: PRV_Run_Lock (transient); cron tick skips if locked; Run-now
   refuses with clear message; lock released in finally block.

8. Design fixes: dark-ink focus ring on bright fills; disabled-row full AA
   contrast (no opacity); toggle disabled on retired rows; save-bar-level
   warning (role=alert); chip text #B4BDC7 6.83:1 AA; keyboard-sortable headers
   (<button>+aria-sort); aria-live on Test chip; z-index:50 save-bar;
   run-now double-fire guard; @media print light overrides.

New: PRV_Upgrader (runs migrations on plugins_loaded, not just activation),
PRV_Config_Version, PRV_Run_Lock, PRV_Settings_Page, PRV_Settings_Renderer,
PRV_Model_Manager_Table, PRV_Model_Test_Ajax.

Tests: test-model-registry, test-run-lock, test-config-version,
       test-projected-cost, test-cron-reschedule (+ updated probe-runner,
       uninstall, bootstrap).

Schema: config_version INT column added via dbDelta (idempotent).
Uninstall: purges all v0.2 prv_* options + transients.

includes/core/class-prv-cron.php

@@ -8,17 +8,21 @@
 declare(strict_types=1);
 
 /**
- * WP-Cron management for the weekly AI-visibility probe.
+ * WP-Cron management for the AI-visibility probe.
  *
  * Registers the prv_weekly_probe hook, schedules/clears the event, and
- * dispatches to PRV_Probe_Runner on each tick.
+ * dispatches to PRV_Probe_Runner on each tick.  Cadence changes clear the
+ * existing schedule and reschedule at the new recurrence so next-run
+ * timestamp reflects the actual cadence, not just the saved option.
  *
  * Who triggers: PRV_Plugin::init() (hook registration), PRV_Activator
- *               (schedule), PRV_Deactivator (clear).
- * Dependencies: PRV_Probe_Runner.
+ *               (schedule), PRV_Deactivator (clear), PRV_Settings_Page
+ *               (reschedule on cadence change).
+ * Dependencies: PRV_Probe_Runner, PRV_Run_Lock.
  *
- * @see class-prv-probe-runner.php — Runner invoked on each cron tick.
- * @see class-prv-activator.php    — Calls schedule_weekly() on activation.
+ * @see class-prv-probe-runner.php  -- Runner invoked on each cron tick.
+ * @see class-prv-activator.php     -- Calls schedule() on activation.
+ * @see class-prv-settings-page.php -- Calls reschedule() on cadence change.
  * @package PrVision
  */
 class PRV_Cron {
@@ -35,34 +39,85 @@ class PRV_Cron {
 	}
 
 	/**
-	 * Callback fired by WP-Cron on the weekly schedule.
+	 * Callback fired by WP-Cron on the scheduled cadence.
+	 *
+	 * Respects the run-lock; if already running (e.g. "Run now" is active)
+	 * the cron tick is skipped silently without double-spending.
 	 *
 	 * Side effects: Instantiates and runs PRV_Probe_Runner.
 	 *
 	 * @return void
 	 */
 	public function handle_cron_tick(): void {
+		if ( PRV_Run_Lock::is_locked() ) {
+			// Another run is in progress -- skip this tick.
+			return;
+		}
 		$runner = new PRV_Probe_Runner();
 		$runner->run();
 	}
 
 	/**
-	 * Schedule the weekly cron event if not already scheduled.
+	 * Schedule the probe cron event using the configured cadence.
 	 *
-	 * Safe to call on re-activation — no-op when already scheduled.
+	 * Safe to call on re-activation -- no-op when already scheduled at the
+	 * correct recurrence; clears and reschedules when recurrence differs.
 	 *
-	 * Side effects: Adds a WP-Cron event.
+	 * Side effects: Adds (or replaces) a WP-Cron event.
+	 *
+	 * @return void
+	 */
+	public static function schedule(): void {
+		$cadence = PRV_Config::get_cadence();
+		$next    = wp_next_scheduled( PRV_CRON_HOOK );
+
+		if ( false !== $next ) {
+			// Check if the current recurrence matches.
+			$events = _get_cron_array();
+			foreach ( $events as $timestamp => $hooks ) {
+				if ( isset( $hooks[ PRV_CRON_HOOK ] ) ) {
+					foreach ( $hooks[ PRV_CRON_HOOK ] as $event ) {
+						if ( isset( $event['schedule'] ) && $event['schedule'] === $cadence ) {
+							return; // Already scheduled at the right cadence.
+						}
+					}
+				}
+			}
+			// Wrong cadence -- clear and reschedule.
+			self::clear_schedule();
+		}
+
+		wp_schedule_event( time(), $cadence, PRV_CRON_HOOK );
+	}
+
+	/**
+	 * Reschedule the cron at a new cadence.
+	 *
+	 * Clears the existing event and creates a new one immediately.
+	 * Called by PRV_Settings_Page when the cadence option changes.
+	 *
+	 * Side effects: Removes existing cron event; adds new one.
+	 *
+	 * @param string $cadence New WP-Cron recurrence identifier.
+	 *
+	 * @return void
+	 */
+	public static function reschedule( string $cadence ): void {
+		self::clear_schedule();
+		wp_schedule_event( time(), $cadence, PRV_CRON_HOOK );
+	}
+
+	/**
+	 * Schedule using the legacy 'weekly' recurrence (activation compat).
 	 *
 	 * @return void
 	 */
 	public static function schedule_weekly(): void {
-		if ( ! wp_next_scheduled( PRV_CRON_HOOK ) ) {
-			wp_schedule_event( time(), 'weekly', PRV_CRON_HOOK );
-		}
+		self::schedule();
 	}
 
 	/**
-	 * Remove the weekly cron schedule.
+	 * Remove the cron schedule.
 	 *
 	 * Called on deactivation. Does not purge data.
 	 *
@@ -78,11 +133,20 @@ class PRV_Cron {
 	}
 
 	/**
-	 * Check whether the weekly event is currently scheduled.
+	 * Check whether the probe event is currently scheduled.
 	 *
 	 * @return bool
 	 */
 	public static function is_scheduled(): bool {
 		return false !== wp_next_scheduled( PRV_CRON_HOOK );
 	}
+
+	/**
+	 * Return the timestamp of the next scheduled run.
+	 *
+	 * @return int|false Timestamp or false if not scheduled.
+	 */
+	public static function next_run_timestamp() {
+		return wp_next_scheduled( PRV_CRON_HOOK );
+	}
 }