From b4588f26af2f74f7b1387b548e04a3c8d81da75b Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Tue, 22 Sep 2026 18:46:17 +0200
Subject: [PATCH] feat(ai,coding-agent): add Claude Opus 5.5 support

---
 packages/ai/CHANGELOG.md                |  1 +
 packages/ai/scripts/generate-models.ts  | 30 +++++++++++++++++++++++--
 packages/ai/test/supports-xhigh.test.ts | 16 +++++++++++++
 packages/coding-agent/CHANGELOG.md      |  4 ++++
 4 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index 4e1b21ead..c749ef03b 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Added
 
+- Added Claude Opus 5.5 to the built-in Anthropic model catalog with adaptive thinking, 1M context, and official pricing metadata.
 - Added Grok 4.7 to the built-in xAI model catalog with long-context pricing metadata.
 
 ### Fixed
diff --git a/packages/ai/scripts/generate-models.ts b/packages/ai/scripts/generate-models.ts
index 7b54f34d3..a611e6b0f 100644
--- a/packages/ai/scripts/generate-models.ts
+++ b/packages/ai/scripts/generate-models.ts
@@ -580,14 +580,14 @@ const MID_CONVO_EFFORT_UNSUPPORTED_ANTHROPIC_MODELS = new Set(["openrouter:anthr
 function supportsAnthropicMidConvoEffort(modelId: string): boolean {
 	const id = modelId.toLowerCase().replace(/^~?anthropic\//, "");
 	return (
-		/^claude-opus-5(?:-\d{8})?$/.test(id) ||
+		/^claude-opus-(?:5|5[.-]5)(?:-\d{8})?$/.test(id) ||
 		/^claude-(?:fable|mythos)-5(?:[.-]1)(?:-\d{8})?$/.test(id)
 	);
 }
 
 function supportsAnthropicMidConvoSystemMessages(modelId: string): boolean {
 	return (
-		/^claude-opus-(?:4[.-]8|5)(?:-\d{8})?$/.test(modelId) ||
+		/^claude-opus-(?:4[.-]8|5(?:[.-]5)?)(?:-\d{8})?$/.test(modelId) ||
 		/^claude-(?:fable|mythos)-5(?:[.-]1)?(?:-\d{8})?$/.test(modelId)
 	);
 }
@@ -2662,6 +2662,32 @@ async function generateModels() {
 			!((model.provider === "opencode" || model.provider === "opencode-go") && model.id === "gpt-5.3-codex-spark"),
 	);
 
+	// Add Claude Opus 5.5 until models.dev includes it.
+	// https://platform.claude.com/docs/en/models/opus-5-5/overview
+	if (!allModels.some((model) => model.provider === "anthropic" && model.id === "claude-opus-5-5")) {
+		allModels.push({
+			id: "claude-opus-5-5",
+			name: "Claude Opus 5.5",
+			api: "anthropic-messages",
+			provider: "anthropic",
+			baseUrl: "https://api.anthropic.com",
+			reasoning: true,
+			thinkingLevelMap: {
+				off: null,
+				minimal: null,
+				low: "low",
+				medium: "medium",
+				high: "high",
+				xhigh: "xhigh",
+				max: "max",
+			},
+			input: ["text", "image"],
+			cost: { input: 4, output: 20, cacheRead: 0.2, cacheWrite: 5 },
+			contextWindow: 1000000,
+			maxTokens: 128000,
+		});
+	}
+
 	// Temporary overrides until upstream model metadata is corrected.
 	for (const candidate of allModels) {
 		if (candidate.provider === "github-copilot" && GITHUB_COPILOT_EXTENDED_CONTEXT_MODELS.has(candidate.id)) {
diff --git a/packages/ai/test/supports-xhigh.test.ts b/packages/ai/test/supports-xhigh.test.ts
index e0ae2629f..bb762e5dc 100644
--- a/packages/ai/test/supports-xhigh.test.ts
+++ b/packages/ai/test/supports-xhigh.test.ts
@@ -23,6 +23,22 @@ describe("getSupportedThinkingLevels", () => {
 		expect(getSupportedThinkingLevels(model!)).toContain("max");
 	});
 
+	it("includes Claude Opus 5.5 with its always-on effort levels and official pricing", () => {
+		const model = getModel("anthropic", "claude-opus-5-5");
+		expect(model).toMatchObject({
+			cost: { input: 4, output: 20, cacheRead: 0.2, cacheWrite: 5 },
+			contextWindow: 1_000_000,
+			maxTokens: 128_000,
+			compat: {
+				forceAdaptiveThinking: true,
+				supportsMidConvoEffort: true,
+				supportsMidConvoSystemMessages: true,
+				supportsMidConvoToolChanges: true,
+			},
+		});
+		expect(getSupportedThinkingLevels(model)).toEqual(["low", "medium", "high", "xhigh", "max"]);
+	});
+
 	it("includes max but not xhigh for Anthropic Sonnet 4.6 on anthropic-messages API", () => {
 		const model = getModel("anthropic", "claude-sonnet-4-6");
 		expect(model).toBeDefined();
diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index b268db98d..ad5f8bb1a 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- Added inherited Claude Opus 5.5 support for Anthropic with adaptive thinking and a 1M context window.
+
 ### Changed
 
 - Changed the default xAI model to Grok 4.7.