feat(ai): add Copilot Claude Sonnet 5

closes #6200

packages/ai/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Added
 
+- Added Claude Sonnet 5 to the GitHub Copilot model catalog ([#6200](https://github.com/earendil-works/pi/issues/6200)).
 - Added zstd request-body compression for the OpenAI Codex Responses SSE transport. Requests are sent with `Content-Encoding: zstd` when Node/Bun zstd support is available; the WebSocket transport is unchanged.
 
 ## [0.80.3] - 2026-06-30

packages/ai/scripts/generate-models.ts

@@ -1361,12 +1361,12 @@ async function loadModelsDevData(): Promise<Model<any>[]> {
 				if (m.tool_call !== true) continue;
 				if (m.status === "deprecated") continue;
 
-				// Claude 4.x models route to Anthropic Messages API
-				const isCopilotClaude4 = /^claude-(haiku|sonnet|opus)-4([.\-]|$)/.test(modelId);
+				// Claude 4.x and 5.x models route to Anthropic Messages API
+				const isCopilotClaude = /^claude-(haiku|sonnet|opus)-[45]([.\-]|$)/.test(modelId);
 				// gpt-5 models require responses API, others use completions
 				const needsResponsesApi = modelId.startsWith("gpt-5") || modelId.startsWith("oswe");
 
-				const api: Api = isCopilotClaude4
+				const api: Api = isCopilotClaude
 					? "anthropic-messages"
 					: needsResponsesApi
 						? "openai-responses"
@@ -1899,6 +1899,17 @@ async function generateModels() {
 		}
 	}
 
+	// Add missing GitHub Copilot Claude Sonnet 5 until models.dev includes it.
+	const anthropicSonnet5 = allModels.find((m) => m.provider === "anthropic" && m.id === "claude-sonnet-5");
+	if (anthropicSonnet5 && !allModels.some((m) => m.provider === "github-copilot" && m.id === "claude-sonnet-5")) {
+		allModels.push({
+			...anthropicSonnet5,
+			provider: "github-copilot",
+			baseUrl: "https://api.individual.githubcopilot.com",
+			headers: { ...COPILOT_STATIC_HEADERS },
+		});
+	}
+
 	if (!allModels.some((m) => m.provider === "openai" && m.id === "gpt-5.4")) {
 		allModels.push({
 			id: "gpt-5.4",

packages/ai/src/providers/github-copilot.models.ts

@@ -178,6 +178,25 @@ export const GITHUB_COPILOT_MODELS = {
 		contextWindow: 1000000,
 		maxTokens: 32000,
 	} satisfies Model<"anthropic-messages">,
+	"claude-sonnet-5": {
+		id: "claude-sonnet-5",
+		name: "Claude Sonnet 5",
+		api: "anthropic-messages",
+		provider: "github-copilot",
+		baseUrl: "https://api.individual.githubcopilot.com",
+		headers: {"User-Agent":"GitHubCopilotChat/0.35.0","Editor-Version":"vscode/1.107.0","Editor-Plugin-Version":"copilot-chat/0.35.0","Copilot-Integration-Id":"vscode-chat"},
+		compat: {"forceAdaptiveThinking":true},
+		reasoning: true,
+		input: ["text", "image"],
+		cost: {
+			input: 2,
+			output: 10,
+			cacheRead: 0.2,
+			cacheWrite: 2.5,
+		},
+		contextWindow: 1000000,
+		maxTokens: 128000,
+	} satisfies Model<"anthropic-messages">,
 	"gemini-2.5-pro": {
 		id: "gemini-2.5-pro",
 		name: "Gemini 2.5 Pro",