From 7d1201d76d4e98be00cc682bedffbae867eac674 Mon Sep 17 00:00:00 2001
From: phranck <phranck@phranck.dev>
Date: Fri, 30 Jan 2026 15:34:38 +0100
Subject: [PATCH] fix: Clear preference callbacks per render pass to prevent
 accumulation (H.4)
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Add PreferenceStorage.beginRenderPass() that clears callbacks and resets
the value stack at the start of each frame. Without this, every render
pass appended duplicate callbacks via OnPreferenceChangeModifier, causing
N callbacks after N renders — each fired on every setValue() call.

Called from RenderLoop.render() alongside the existing clearHandlers()
and focusManager.clear() calls. Follows the same per-frame reset pattern.

Remove unused clearCallbacks() method (dead code, never called).
---
 Sources/TUIKit/App/RenderLoop.swift   |  3 ++-
 Sources/TUIKit/Core/Preferences.swift | 11 +++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Sources/TUIKit/App/RenderLoop.swift b/Sources/TUIKit/App/RenderLoop.swift
index f836662..3f274ee 100644
--- a/Sources/TUIKit/App/RenderLoop.swift
+++ b/Sources/TUIKit/App/RenderLoop.swift
@@ -50,8 +50,9 @@ internal struct RenderLoop<A: App> {
     /// 4. Ends lifecycle tracking (triggers `onDisappear` for removed views)
     /// 5. Renders the status bar at the bottom
     func render() {
-        // Clear event handlers before re-rendering
+        // Clear per-frame state before re-rendering
         tuiContext.keyEventDispatcher.clearHandlers()
+        tuiContext.preferences.beginRenderPass()
         focusManager.clear()
 
         // Begin lifecycle tracking for this render pass
diff --git a/Sources/TUIKit/Core/Preferences.swift b/Sources/TUIKit/Core/Preferences.swift
index 011b5b5..7f763d6 100644
--- a/Sources/TUIKit/Core/Preferences.swift
+++ b/Sources/TUIKit/Core/Preferences.swift
@@ -174,12 +174,19 @@ public final class PreferenceStorage: @unchecked Sendable {
         callbacks[keyId]?.append(wrappedCallback)
     }
 
-    /// Clears all callbacks.
-    public func clearCallbacks() {
+    /// Prepares preference storage for a new render pass.
+    ///
+    /// Clears all accumulated callbacks and resets the value stack
+    /// to a single empty context. Called at the start of each frame
+    /// by ``RenderLoop/render()`` to prevent callback accumulation.
+    public func beginRenderPass() {
         callbacks.removeAll()
+        stack = [PreferenceValues()]
     }
 
     /// Resets all preference state.
+    ///
+    /// Called once during app shutdown by ``TUIContext/reset()``.
     public func reset() {
         stack = [PreferenceValues()]
         callbacks.removeAll()