fix(coding-agent): add OpenCode session headers

closes #4847

packages/coding-agent/CHANGELOG.md

@@ -13,6 +13,7 @@
 
 ### Fixed
 
+- Fixed OpenCode Zen/Go requests to send per-session OpenCode routing headers ([#4847](https://github.com/earendil-works/pi/issues/4847)).
 - Fixed Amazon Bedrock provider loading under strict package managers by inheriting the declared `@smithy/node-http-handler` dependency from `@earendil-works/pi-ai` ([#4842](https://github.com/earendil-works/pi/issues/4842)).
 - Fixed exported session HTML to escape quote characters in attribute values ([#4832](https://github.com/earendil-works/pi/issues/4832)).
 - Fixed GitHub Copilot device-code login to keep opening the verification URL in browser-capable environments while ignoring browser launch failures for headless use.

packages/coding-agent/src/core/sdk.ts

@@ -129,7 +129,15 @@ function getDefaultAgentDir(): string {
 function getAttributionHeaders(
 	model: Model<any>,
 	settingsManager: SettingsManager,
+	sessionId?: string,
 ): Record<string, string> | undefined {
+	if (
+		sessionId &&
+		(model.provider === "opencode" || model.provider === "opencode-go" || model.baseUrl.includes("opencode.ai"))
+	) {
+		return { "x-opencode-session": sessionId, "x-opencode-client": "pi" };
+	}
+
 	if (!isInstallTelemetryEnabled(settingsManager)) {
 		return undefined;
 	}
@@ -332,7 +340,7 @@ export async function createAgentSession(options: CreateAgentSessionOptions = {}
 				throw new Error(auth.error);
 			}
 			const providerRetrySettings = settingsManager.getProviderRetrySettings();
-			const attributionHeaders = getAttributionHeaders(model, settingsManager);
+			const attributionHeaders = getAttributionHeaders(model, settingsManager, options?.sessionId);
 			return streamSimple(model, context, {
 				...options,
 				apiKey: auth.apiKey,

packages/coding-agent/test/sdk-openrouter-attribution.test.ts

@@ -86,6 +86,7 @@ describe("createAgentSession OpenRouter attribution headers", () => {
 			telemetryEnabled?: boolean;
 			providerHeaders?: Record<string, string>;
 			requestHeaders?: Record<string, string>;
+			sessionId?: string;
 		} = {},
 	): Promise<Record<string, string> | undefined> {
 		const settingsManager = SettingsManager.create(cwd, agentDir);
@@ -112,6 +113,11 @@ describe("createAgentSession OpenRouter attribution headers", () => {
 			registeredProviders.push(model.provider);
 		}
 
+		const sessionManager = SessionManager.inMemory(cwd);
+		if (options.sessionId) {
+			sessionManager.newSession({ id: options.sessionId });
+		}
+
 		const { session } = await createAgentSession({
 			cwd,
 			agentDir,
@@ -119,14 +125,17 @@ describe("createAgentSession OpenRouter attribution headers", () => {
 			authStorage,
 			modelRegistry,
 			settingsManager,
-			sessionManager: SessionManager.inMemory(cwd),
+			sessionManager,
 		});
 
 		try {
 			await session.agent.streamFn(
 				model,
 				{ messages: [] },
-				options.requestHeaders ? { headers: options.requestHeaders } : undefined,
+				{
+					sessionId: session.sessionId,
+					...(options.requestHeaders ? { headers: options.requestHeaders } : {}),
+				},
 			);
 			return capturedOptions?.headers;
 		} finally {
@@ -178,4 +187,26 @@ describe("createAgentSession OpenRouter attribution headers", () => {
 		expect(headers?.["X-OpenRouter-Title"]).toBe("request-title");
 		expect(headers?.["X-OpenRouter-Categories"]).toBe("provider-category");
 	});
+
+	it("adds OpenCode session headers", async () => {
+		const headers = await captureHeaders(createModel("opencode", "https://opencode.ai/zen/v1"), {
+			sessionId: "opencode-session",
+		});
+
+		expect(headers?.["x-opencode-session"]).toBe("opencode-session");
+		expect(headers?.["x-opencode-client"]).toBe("pi");
+	});
+
+	it("lets configured OpenCode headers override the defaults", async () => {
+		const headers = await captureHeaders(createModel("opencode", "https://opencode.ai/zen/v1"), {
+			sessionId: "opencode-session",
+			providerHeaders: {
+				"x-opencode-session": "configured-session",
+				"x-opencode-client": "configured-client",
+			},
+		});
+
+		expect(headers?.["x-opencode-session"]).toBe("configured-session");
+		expect(headers?.["x-opencode-client"]).toBe("configured-client");
+	});
 });