From ab373716e7c996084fd8383fca210063a87773e7 Mon Sep 17 00:00:00 2001
From: "Bob.Hou" <364432949@qq.com>
Date: Tue, 4 Aug 2026 00:27:33 -0400
Subject: [PATCH] fix: add claude-opus-5 to KNOWN_MODEL_WINDOW_TOKENS (#2609)

* fix: add claude-opus-5 to KNOWN_MODEL_WINDOW_TOKENS

claude-opus-5 has a 1M context window (verified: 250k tokens at 25%
usage = ~1M), but was missing from the model table. This caused
resolveContextWindowTokens() to fall back to the 200k default when
tokens < 200k, incorrectly triggering compact warnings in the first
20% of a 1M session.

Same failure class as #2290 (Opus 4.x) and #2461 (fable-5/mythos-5).
The env override (ECC_CONTEXT_WINDOW_TOKENS) remains the escape hatch
for unlisted models.

Refs: #2290, #2461, #2468

* test: add regression test for claude-opus-5 context window

Verifies resolveContextWindowTokens returns LARGE_CONTEXT_WINDOW_TOKENS
for claude-opus-5 at 50k tokens, matching the behavior of fable-5 and
mythos-5 in the known-model table.
---
 scripts/lib/transcript-context.js    | 1 +
 tests/lib/transcript-context.test.js | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/scripts/lib/transcript-context.js b/scripts/lib/transcript-context.js
index d8df7411a..201861487 100644
--- a/scripts/lib/transcript-context.js
+++ b/scripts/lib/transcript-context.js
@@ -35,6 +35,7 @@ const LARGE_WINDOW_MODEL_MARKER = '[1m]';
 // Checked in order, first match wins. Best-effort and expected to lag new
 // releases; the env override remains the escape hatch for unlisted models.
 const KNOWN_MODEL_WINDOW_TOKENS = [
+  ['claude-opus-5', LARGE_CONTEXT_WINDOW_TOKENS],
   ['claude-fable-5', LARGE_CONTEXT_WINDOW_TOKENS],
   ['claude-mythos-5', LARGE_CONTEXT_WINDOW_TOKENS]
 ];
diff --git a/tests/lib/transcript-context.test.js b/tests/lib/transcript-context.test.js
index 4f95c62b4..1d335f131 100644
--- a/tests/lib/transcript-context.test.js
+++ b/tests/lib/transcript-context.test.js
@@ -188,6 +188,10 @@ test('recognizes claude-mythos-5 as a 1M window from the known-model table (#246
   assert.strictEqual(resolveContextWindowTokens(50000, 'claude-mythos-5'), LARGE_CONTEXT_WINDOW_TOKENS);
 });
 
+test('recognizes claude-opus-5 as a 1M window from the known-model table', () => {
+  assert.strictEqual(resolveContextWindowTokens(50000, 'claude-opus-5'), LARGE_CONTEXT_WINDOW_TOKENS);
+});
+
 test('recognizes dated/prefixed variants of known large-window model ids (#2461)', () => {
   assert.strictEqual(resolveContextWindowTokens(50000, 'us.anthropic.claude-fable-5-20260115-v1:0'), LARGE_CONTEXT_WINDOW_TOKENS);
 });