WIP

packages/svelte/src/internal/client/dev/tracing.js

@@ -4,6 +4,7 @@ import { snapshot } from '../../shared/clone.js';
 import { DERIVED, ASYNC, PROXY_PATH_SYMBOL, STATE_SYMBOL } from '#client/constants';
 import { effect_tracking } from '../reactivity/effects.js';
 import { active_reaction, untrack } from '../runtime.js';
+import { get_cv, get_wv } from '../reactivity/batch.js';
 
 /**
  * @typedef {{
@@ -27,7 +28,7 @@ function log_entry(signal, entry) {
 
 	const type = get_type(signal);
 	const current_reaction = /** @type {Reaction} */ (active_reaction);
-	const dirty = signal.wv > current_reaction.wv || current_reaction.wv === 0;
+	const dirty = get_wv(signal) > get_cv(current_reaction);
 	const style = dirty
 		? 'color: CornflowerBlue; font-weight: bold'
 		: 'color: grey; font-weight: normal';

packages/svelte/src/internal/client/reactivity/batch.js

@@ -1285,13 +1285,27 @@ export function fork(fn) {
 	};
 }
 
+/**
+ * @param {Value} value
+ */
+export function get_wv(value) {
+	return batch_wvs?.get(value) ?? value.wv;
+}
+
+/**
+ * @param {Reaction} reaction
+ */
+export function get_cv(reaction) {
+	return batch_cvs?.get(reaction) ?? reaction.cv;
+}
+
 /**
  * @param {Reaction} reaction
  */
-export function set_cv(reaction) {
-	current_batch?.cvs.set(reaction, write_version);
-	batch_cvs?.set(reaction, write_version);
-	reaction.cv = write_version;
+export function set_cv(reaction, cv = write_version) {
+	current_batch?.cvs.set(reaction, cv);
+	batch_cvs?.set(reaction, cv);
+	reaction.cv = cv;
 }
 
 /**

packages/svelte/src/internal/client/runtime.js

@@ -53,6 +53,7 @@ import {
 	batch_wvs,
 	current_batch,
 	flushSync,
+	get_cv,
 	schedule_effect,
 	set_cv
 } from './reactivity/batch.js';
@@ -176,7 +177,7 @@ export function is_dirty(reaction) {
 		return false;
 	}
 
-	var cv = batch_cvs?.get(reaction) ?? reaction.cv;
+	var cv = get_cv(reaction);
 
 	var length = dependencies.length;
 
@@ -454,13 +455,18 @@ export function update_effect(effect) {
 			destroy_effect_children(effect);
 		}
 
-		set_cv(effect);
+		// get this now, so that any writes during execution cause a re-run,
+		// but don't set it yet so that `$inspect.trace` works
+		const cv = write_version;
 
 		execute_effect_teardown(effect);
 		var teardown = update_reaction(effect);
 		effect.teardown = typeof teardown === 'function' ? teardown : null;
 
-		if (!is_runes()) {
+		if (is_runes()) {
+			set_cv(effect, cv);
+		} else {
+			// in legacy mode, prevent the effect re-running immediately
 			set_cv(effect);
 		}