From 9916955b967a858aff5554c40f65cf9197dda480 Mon Sep 17 00:00:00 2001
From: Ku6epXBOCTuK <Ku6epXBOCTuK@gmail.com>
Date: Fri, 9 Oct 2026 21:23:41 +0500
Subject: [PATCH] refactor: use derived by instead of effect

---
 docs/architecture-audit-2026-10.md            |  8 ++--
 .../components/schema/SchemaToolView.svelte   | 48 ++++++++-----------
 2 files changed, 25 insertions(+), 31 deletions(-)

diff --git a/docs/architecture-audit-2026-10.md b/docs/architecture-audit-2026-10.md
index 9ebea10..b39cc64 100644
--- a/docs/architecture-audit-2026-10.md
+++ b/docs/architecture-audit-2026-10.md
@@ -52,11 +52,11 @@
 
 ## Med
 
-### M1. Маски через `$effect` вместо `$derived.by`
+### M1. Маски через `$effect` вместо `$derived.by` — СДЕЛАНО (2026-10)
 
-`SchemaToolView.svelte:579-600`: `$effect` чисто вычисляет `maskResults` из
-`steps`/`stepResults`/`source`/`maskOnKeys` и пишет в `$state`. `runMask`
-синхронный и чистый — учебниковый случай `$derived.by`, эффект не нужен.
+`SchemaToolView.svelte`: эффект вычисления `maskResults` заменён на
+`$derived.by`; ручной сброс `maskResults = {}` в `init()` удалён — derived
+пересчитывается сам по смене `steps`/`source`/`maskOnKeys`.
 
 ### M2. `init()` в эффекте не сбрасывает часть состояния
 
diff --git a/web/src/lib/components/schema/SchemaToolView.svelte b/web/src/lib/components/schema/SchemaToolView.svelte
index b27393b..057d6e7 100644
--- a/web/src/lib/components/schema/SchemaToolView.svelte
+++ b/web/src/lib/components/schema/SchemaToolView.svelte
@@ -138,7 +138,27 @@
 	// Mask preview per step (keyed by step.key): the toggle lives on every
 	// step result tile, not just the final one.
 	const maskOnKeys = new SvelteSet<string>();
-	let maskResults = $state<Record<string, PixelImage | null>>({});
+	// Mask preview: recomputed on the main thread per toggled step from that
+	// step's input; a mask never enters the chain itself.
+	const maskResults = $derived.by(() => {
+		const next: Record<string, PixelImage | null> = {};
+		steps.forEach((step, i) => {
+			if (!maskOnKeys.has(step.key)) return;
+			const stepTool = getTool(step.id);
+			if (!stepTool?.runMask) return;
+			const input = i === 0 ? source : stepResults[i - 1];
+			if (!input) return;
+			try {
+				next[step.key] = stepTool.runMask({
+					params: step.params,
+					source: input,
+				});
+			} catch {
+				next[step.key] = null;
+			}
+		});
+		return next;
+	});
 	let dragFrom = $state<number | null>(null);
 
 	const lastTool = $derived(
@@ -255,7 +275,6 @@
 		verdictVars = undefined;
 		displayError = null;
 		maskOnKeys.clear();
-		maskResults = {};
 	}
 
 	function setStepValue(
@@ -582,31 +601,6 @@
 		return () => debouncedRun.cancel();
 	});
 
-	// Mask preview: recomputed on the main thread per toggled step from that
-	// step's input; a mask never enters the chain itself.
-	$effect(() => {
-		void steps;
-		void stepResults;
-		void source;
-		const next: Record<string, PixelImage | null> = {};
-		steps.forEach((step, i) => {
-			if (!maskOnKeys.has(step.key)) return;
-			const stepTool = getTool(step.id);
-			if (!stepTool?.runMask) return;
-			const input = i === 0 ? source : stepResults[i - 1];
-			if (!input) return;
-			try {
-				next[step.key] = stepTool.runMask({
-					params: step.params,
-					source: input,
-				});
-			} catch {
-				next[step.key] = null;
-			}
-		});
-		maskResults = next;
-	});
-
 	function toggleStepMask(key: string) {
 		if (maskOnKeys.has(key)) maskOnKeys.delete(key);
 		else maskOnKeys.add(key);