From 1bd8bb76cbeddb698a3ad46496ca468117b29988 Mon Sep 17 00:00:00 2001
From: Romil Bijarnia <romilbij@gmail.com>
Date: Wed, 11 Nov 2026 19:16:09 +1100
Subject: [PATCH] fix(client): bound delimiter scans while parsing model
 references

---
 .../src/composerModelMentions.test.ts         | 14 +++++++++----
 .../src/composerModelMentions.ts              | 21 ++++++++++++-------
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/packages/client-runtime/src/composerModelMentions.test.ts b/packages/client-runtime/src/composerModelMentions.test.ts
index b6a51a71301fe..dfd0f6ac9acb5 100644
--- a/packages/client-runtime/src/composerModelMentions.test.ts
+++ b/packages/client-runtime/src/composerModelMentions.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vite-plus/test";
+import { describe, expect, it, vi } from "vite-plus/test";
 
 import {
   collectComposerModelMentions,
@@ -85,10 +85,16 @@ describe("collectComposerModelMentions", () => {
     ["model:codex/gpt-6.1,model:claudeAgent/sonnet", ["codex/gpt-6.1", "claudeAgent/sonnet"]],
     ["model:codex/gpt-6.1's output", ["codex/gpt-6.1"]],
     ["model:opencode/foo(bar)", ["opencode/foo(bar)"]],
+    ["(model:codex/GPT-6.1-Sol[1m]).", ["codex/GPT-6.1-Sol[1m]"]],
+    ["model:codex/gpt-6.1" + ")".repeat(128), ["codex/gpt-6.1"]],
   ])("bounds the reference in %s", (text, expected) => {
-    expect(
-      collectComposerModelMentions(text).map(({ instanceId, model }) => `${instanceId}/${model}`),
-    ).toEqual(expected);
+    const { mentions, rescans } = (() => {
+      using split = vi.spyOn(String.prototype, "split");
+      const mentions = collectComposerModelMentions(text);
+      return { mentions, rescans: split.mock.calls.length };
+    })();
+    expect(mentions.map(({ instanceId, model }) => `${instanceId}/${model}`)).toEqual(expected);
+    expect(rescans).toBeLessThanOrEqual(expected.length * 4);
   });
 
   it.each(["remodel:codex/gpt", "model:codex", "model:/gpt", "model:codex/.", "model:1x/gpt"])(
diff --git a/packages/client-runtime/src/composerModelMentions.ts b/packages/client-runtime/src/composerModelMentions.ts
index 29af1b8deb73b..140786d778ee2 100644
--- a/packages/client-runtime/src/composerModelMentions.ts
+++ b/packages/client-runtime/src/composerModelMentions.ts
@@ -68,15 +68,22 @@ function countOf(text: string, char: string): number {
 
 // Slugs like `foo(bar)` or `GPT-6.1-Sol[1m]` keep balanced brackets; prose wrapping them does not.
 function trimModelSlug(slug: string): string {
-  let trimmed = slug;
-  while (trimmed.length > 0) {
-    const last = trimmed.at(-1)!;
+  let end = slug.length;
+  const unmatched = new Map<string, number>();
+  while (end > 0) {
+    const last = slug[end - 1]!;
+    if (SENTENCE_PUNCTUATION.includes(last)) {
+      end -= 1;
+      continue;
+    }
     const opening = CLOSING_BRACKETS[last];
-    const unbalanced = opening !== undefined && countOf(trimmed, opening) < countOf(trimmed, last);
-    if (!SENTENCE_PUNCTUATION.includes(last) && !unbalanced) break;
-    trimmed = trimmed.slice(0, -1);
+    if (opening === undefined) break;
+    const excess = unmatched.get(last) ?? countOf(slug, last) - countOf(slug, opening);
+    if (excess <= 0) break;
+    unmatched.set(last, excess - 1);
+    end -= 1;
   }
-  return trimmed;
+  return slug.slice(0, end);
 }
 
 /** Finds the `model:<instance>/<model>` references that `formatComposerModelMention` writes. */