From e32f81d4454484808eabf9bc306b27a3bea80e16 Mon Sep 17 00:00:00 2001
From: BlueX888 <140241684+BlueX888@users.noreply.github.com>
Date: Tue, 1 Sep 2026 21:35:55 +0800
Subject: [PATCH] fix(router): prefer exact tier match over word-prefix
 fallback in parseTier

The token-saver fallback parser iterated knownTiers in order with a
word-boundary regex. Because '-' is a word boundary, a tier that is a
word-prefix of a hyphenated tier (e.g. 'fast' vs 'fast-pro') matched
first and won even when the judge output named the longer tier exactly.

Check exact (case-insensitive) equality against known tiers before the
regex fallback, and sort fallback candidates longest-first so free-text
mentions also resolve to the most specific tier.

Fixes #428
---
 src/router/tokenSaver/parseTier.ts |  9 ++++++++-
 tests/router/parseTier.spec.ts     | 29 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 tests/router/parseTier.spec.ts

diff --git a/src/router/tokenSaver/parseTier.ts b/src/router/tokenSaver/parseTier.ts
index f863780bb..7893794b1 100644
--- a/src/router/tokenSaver/parseTier.ts
+++ b/src/router/tokenSaver/parseTier.ts
@@ -10,7 +10,14 @@ export function parseTier(judgeOutput: string, knownTiers: string[]): string | u
     if (found) return found;
   }
 
-  for (const tier of knownTiers) {
+  const exact = knownTiers.find(t => t.toLowerCase() === cleaned.toLowerCase());
+  if (exact) return exact;
+
+  // Longest tiers first: `-` is a word boundary, so a shorter tier that is a
+  // word-prefix of a hyphenated tier (e.g. "fast" vs "fast-pro") would
+  // otherwise match inside the longer name.
+  const byLength = [...knownTiers].sort((a, b) => b.length - a.length);
+  for (const tier of byLength) {
     const pattern = new RegExp(`\\b${escapeRegex(tier)}\\b`, "i");
     if (pattern.test(cleaned)) {
       return tier;
diff --git a/tests/router/parseTier.spec.ts b/tests/router/parseTier.spec.ts
new file mode 100644
index 000000000..dd62d59b3
--- /dev/null
+++ b/tests/router/parseTier.spec.ts
@@ -0,0 +1,29 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { parseTier } from "../../src/router/tokenSaver/parseTier.js";
+
+test("prefers an exact tier over a word-prefix of a hyphenated tier", () => {
+  assert.equal(parseTier("a-a", ["a", "a-a"]), "a-a");
+  assert.equal(parseTier("fast-pro", ["fast", "fast-pro"]), "fast-pro");
+});
+
+test("keeps exact matching case-insensitive", () => {
+  assert.equal(parseTier("Fast-Pro", ["fast", "fast-pro"]), "fast-pro");
+});
+
+test("tagged output still resolves the longer tier", () => {
+  assert.equal(parseTier("<tier>a-a</tier>", ["a", "a-a"]), "a-a");
+});
+
+test("fallback text matching picks the longest tier mentioned", () => {
+  assert.equal(parseTier("please use a-a", ["a", "a-a"]), "a-a");
+});
+
+test("fallback text matching still resolves a plain tier mention", () => {
+  assert.equal(parseTier("the answer is fast", ["fast", "fast-pro"]), "fast");
+});
+
+test("returns undefined when no tier matches", () => {
+  assert.equal(parseTier("no such tier", ["fast", "fast-pro"]), undefined);
+});