chore: keep main's code where the branch's change isn't needed

- record block effects as maybe-dirty during traversal
- drop the extra DIRTY guard in #process
- delete deriveds from batch_values in mark_reactions
- don't queue a microtask flush in Batch.ensure during flushSync
- BranchManager commit loop
- capture order in update_derived

packages/svelte/src/internal/client/dom/blocks/branches.js

@@ -110,16 +110,14 @@ export class BranchManager {
 			}
 		}
 
-		this.#batches.delete(batch);
-
 		for (const [b, k] of this.#batches) {
-			if (b.id > batch.id) {
+			this.#batches.delete(b);
+
+			if (b === batch) {
 				// keep values for newer batches
-				continue;
+				break;
 			}
 
-			this.#batches.delete(b);
-
 			const offscreen = this.#offscreen.get(k);
 
 			if (offscreen) {

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

@@ -429,10 +429,9 @@ export class Batch {
 		// an if block that contains the last blocking pending effect falsy,
 		// causing the block to no longer be deferred.
 		for (const [reaction, status] of this.#dirty_reactions) {
-			if ((reaction.f & DERIVED) !== 0) {
-				set_signal_status(reaction, status);
-			} else if (status === DIRTY || (reaction.f & DIRTY) === 0) {
-				set_signal_status(reaction, status);
+			set_signal_status(reaction, status);
+
+			if ((reaction.f & DERIVED) === 0) {
 				this.schedule(/** @type {Effect} */ (reaction));
 			}
 		}
@@ -585,6 +584,7 @@ export class Batch {
 				} else if (async_mode_flag && (flags & (RENDER_EFFECT | MANAGED_EFFECT)) !== 0) {
 					render_effects.push(effect);
 				} else if (is_dirty(effect)) {
+					if ((flags & BLOCK_EFFECT) !== 0) this.add_dirty_reaction(effect, MAYBE_DIRTY);
 					update_effect(effect);
 				}
 
@@ -959,7 +959,7 @@ export class Batch {
 		if (current_batch === null) {
 			const batch = (current_batch = new Batch());
 
-			if (!is_processing) {
+			if (!is_processing && !is_flushing_sync) {
 				queue_micro_task(() => {
 					if (!batch.started) {
 						batch.flush();

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

@@ -421,8 +421,8 @@ export function update_derived(derived) {
 			// to the previous batch, not the new one (which can already exist if an earlier
 			// effect wrote to a source). Not adding it to either can cause bugs, so we add it to both.
 			// See https://github.com/sveltejs/svelte/pull/18117 for more details.
-			previous_batch?.capture(derived, value, true);
 			current_batch?.capture(derived, value, true);
+			previous_batch?.capture(derived, value, true);
 		} else {
 			derived.v = value;
 			derived.wv = increment_write_version();

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

@@ -416,6 +416,7 @@ function mark_reactions(signal, status, updated_during_traversal) {
 		} else if ((flags & DERIVED) !== 0) {
 			var derived = /** @type {Derived} */ (reaction);
 
+			batch_values?.delete(derived);
 			mark_reactions(derived, MAYBE_DIRTY, updated_during_traversal);
 		} else if (not_dirty) {
 			var effect = /** @type {Effect} */ (reaction);