From 41544fb952aef84fcf6ff5d9a5284cf2b2985053 Mon Sep 17 00:00:00 2001
From: Martin Klein <36695017+flitzrrr@users.noreply.github.com>
Date: Sun, 11 Oct 2026 12:10:13 +0200
Subject: [PATCH] perf(javascript): skip the repeated-prefix scan on first
 capture visits (#1789)

Review follow-up. Only a capture already on the alias chain can repeat a prefix, so a first visit no longer slices and serializes every suffix of its path.
---
 .../javascript/javascriptSemanticMemberMutations.ts   | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/domain/javascript/javascriptSemanticMemberMutations.ts b/src/domain/javascript/javascriptSemanticMemberMutations.ts
index 52d4b25dad..62df4c38cb 100644
--- a/src/domain/javascript/javascriptSemanticMemberMutations.ts
+++ b/src/domain/javascript/javascriptSemanticMemberMutations.ts
@@ -139,8 +139,15 @@ export function* collectSemanticMemberMutationsSteps(
         // same prefix added on every cycle, so exact paths never repeat. When
         // that prefix can never be pruned, escaping it once covers every longer
         // effect, including writes below shared children.
+        // Only a capture already on this alias chain can repeat a prefix.
+        const captureKey = JSON.stringify(capture);
+        const revisited = current.bindings.has(captureKey);
         let repeatedPrefix: PropertyPath | undefined;
-        for (let start = 1; start <= current.path.length; start++) {
+        for (
+          let start = 1;
+          revisited && start <= current.path.length;
+          start++
+        ) {
           const suffix = current.path.slice(start);
           if (!current.bindings.has(JSON.stringify([...capture, suffix])))
             continue;
@@ -240,7 +247,7 @@ export function* collectSemanticMemberMutationsSteps(
         const primitiveWrite =
           value?.status === "literal" || value?.status === "union";
         recordedEffects.add(identity);
-        const nested = new Set([...current.bindings, lifetime]);
+        const nested = new Set([...current.bindings, lifetime, captureKey]);
         const origins =
           current.originAt === undefined
             ? binding