fix(coding-agent): preserve Copilot summary endpoint

closes #6768

packages/coding-agent/CHANGELOG.md

@@ -108,6 +108,7 @@
 - Fixed cancellation while waiting for file-backed credential or model-catalog locks, preventing cancelled mutations from running or committing later.
 - Fixed concurrent in-memory credential mutations losing unrelated provider updates by serializing their read-modify-write sections.
 - Updated `undici` to 8.9.0 and the packaged `brace-expansion` to 5.0.9 to address GHSA-8xcm-r25x-g524, GHSA-4cwx-7wf7-3272, GHSA-m8rv-5g2x-5cg5, GHSA-jr45-8vmc-qm54, GHSA-v3r7-h72x-cjcm, and GHSA-rgw5-rvv9-x895.
+- Fixed GitHub Copilot compaction and branch summaries using the Individual endpoint instead of the credential-resolved Business or Enterprise endpoint ([#6768](https://github.com/earendil-works/pi/issues/6768)).
 
 ## [0.83.0] - 2026-07-29
 

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

@@ -26,6 +26,7 @@ import type {
 } from "@earendil-works/pi-agent-core";
 import { contentText } from "@earendil-works/pi-ai";
 import type {
+	Api,
 	AssistantMessage,
 	AuthResult,
 	ImageContent,
@@ -406,7 +407,10 @@ export class AgentSession {
 		return this._modelRuntime;
 	}
 
-	private async _getRequiredRequestAuth(model: Model<any>): Promise<{
+	private async _getRequiredRequestAuth<TApi extends Api>(
+		model: Model<TApi>,
+	): Promise<{
+		model: Model<TApi>;
 		apiKey?: string;
 		headers?: Record<string, string>;
 		env?: Record<string, string>;
@@ -422,7 +426,9 @@ export class AgentSession {
 			throw error;
 		}
 		if (result && (result.auth.apiKey || result.auth.headers)) {
+			const requestModel = result.auth.baseUrl ? { ...model, baseUrl: result.auth.baseUrl } : model;
 			return {
+				model: requestModel,
 				apiKey: result.auth.apiKey,
 				headers: withoutDeletedHeaders(result.auth.headers),
 				env: result.env,
@@ -440,7 +446,10 @@ export class AgentSession {
 		throw new Error(formatNoApiKeyFoundMessage(model.provider));
 	}
 
-	private async _getSummarizationRequestAuth(model: Model<any>): Promise<{
+	private async _getSummarizationRequestAuth<TApi extends Api>(
+		model: Model<TApi>,
+	): Promise<{
+		model: Model<TApi>;
 		apiKey?: string;
 		headers?: Record<string, string>;
 		env?: Record<string, string>;
@@ -451,11 +460,16 @@ export class AgentSession {
 
 		try {
 			const result = await this._modelRuntime.getAuth(model);
-			return result
-				? { apiKey: result.auth.apiKey, headers: withoutDeletedHeaders(result.auth.headers), env: result.env }
-				: {};
+			if (!result) return { model };
+			const requestModel = result.auth.baseUrl ? { ...model, baseUrl: result.auth.baseUrl } : model;
+			return {
+				model: requestModel,
+				apiKey: result.auth.apiKey,
+				headers: withoutDeletedHeaders(result.auth.headers),
+				env: result.env,
+			};
 		} catch {
-			return {};
+			return { model };
 		}
 	}
 
@@ -1788,7 +1802,7 @@ export class AgentSession {
 				throw new Error(formatNoModelSelectedMessage());
 			}
 
-			const { apiKey, headers, env } = await this._getSummarizationRequestAuth(this.model);
+			const { model: requestModel, apiKey, headers, env } = await this._getSummarizationRequestAuth(this.model);
 
 			const pathEntries = this.sessionManager.getBranch();
 			const settings = this.settingsManager.getCompactionSettings();
@@ -1844,7 +1858,7 @@ export class AgentSession {
 				// Generate compaction result
 				const result = await compact(
 					preparation,
-					this.model,
+					requestModel,
 					apiKey,
 					headers,
 					customInstructions,
@@ -2052,14 +2066,7 @@ export class AgentSession {
 				return false;
 			}
 
-			let apiKey: string | undefined;
-			let headers: Record<string, string> | undefined;
-			let env: Record<string, string> | undefined;
-			if (this.agent.streamFunction === streamSimple) {
-				({ apiKey, headers, env } = await this._getRequiredRequestAuth(this.model));
-			} else {
-				({ apiKey, headers, env } = await this._getSummarizationRequestAuth(this.model));
-			}
+			const { model: requestModel, apiKey, headers, env } = await this._getSummarizationRequestAuth(this.model);
 
 			const pathEntries = this.sessionManager.getBranch();
 
@@ -2120,7 +2127,7 @@ export class AgentSession {
 				// Generate compaction result
 				const compactResult = await compact(
 					preparation,
-					this.model,
+					requestModel,
 					apiKey,
 					headers,
 					undefined,
@@ -2985,10 +2992,10 @@ export class AgentSession {
 			let summaryUsage: Usage | undefined;
 			if (options.summarize && entriesToSummarize.length > 0 && !extensionSummary) {
 				const model = this.model!;
-				const { apiKey, headers, env } = await this._getSummarizationRequestAuth(model);
+				const { model: requestModel, apiKey, headers, env } = await this._getSummarizationRequestAuth(model);
 				const branchSummarySettings = this.settingsManager.getBranchSummarySettings();
 				const result = await generateBranchSummary(entriesToSummarize, {
-					model,
+					model: requestModel,
 					apiKey,
 					headers,
 					env,

packages/coding-agent/test/suite/regressions/6768-copilot-compaction-base-url.test.ts

@@ -0,0 +1,114 @@
+import {
+	type AssistantMessage,
+	createAssistantMessageEventStream,
+	fauxAssistantMessage,
+	type Model,
+	type Provider,
+} from "@earendil-works/pi-ai";
+import { afterEach, describe, expect, it } from "vitest";
+import { createHarness, type Harness } from "../harness.ts";
+
+const INDIVIDUAL_BASE_URL = "https://api.individual.githubcopilot.com";
+const ENTERPRISE_BASE_URL = "https://api.enterprise.githubcopilot.com";
+
+function seedCompactableSession(harness: Harness): void {
+	harness.settingsManager.applyOverrides({ compaction: { keepRecentTokens: 1 } });
+	const now = Date.now();
+	harness.sessionManager.appendMessage({
+		role: "user",
+		content: [{ type: "text", text: "message to compact" }],
+		timestamp: now - 1000,
+	});
+	const model = harness.getModel();
+	const assistant: AssistantMessage = {
+		...fauxAssistantMessage("assistant response to compact", { timestamp: now - 500 }),
+		api: model.api,
+		provider: model.provider,
+		model: model.id,
+		usage: {
+			input: 100,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 100,
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+		},
+	};
+	harness.sessionManager.appendMessage(assistant);
+	harness.session.agent.state.messages = harness.sessionManager.buildSessionContext().messages;
+}
+
+describe("issue #6768 Copilot compaction base URL", () => {
+	let harness: Harness | undefined;
+
+	afterEach(() => {
+		harness?.cleanup();
+		harness = undefined;
+	});
+
+	it("uses the auth-resolved base URL through the SDK-style stream wrapper", async () => {
+		harness = await createHarness();
+		seedCompactableSession(harness);
+		const catalogModel = { ...harness.getModel(), baseUrl: INDIVIDUAL_BASE_URL };
+		harness.session.agent.state.model = catalogModel;
+
+		let requestBaseUrl: string | undefined;
+		const respond = (requestModel: Model<string>) => {
+			requestBaseUrl = requestModel.baseUrl;
+			const stream = createAssistantMessageEventStream();
+			stream.push({
+				type: "done",
+				reason: "stop",
+				message: {
+					...fauxAssistantMessage("summary"),
+					api: requestModel.api,
+					provider: requestModel.provider,
+					model: requestModel.id,
+				},
+			});
+			return stream;
+		};
+		const provider: Provider<string> = {
+			id: catalogModel.provider,
+			name: "Copilot regression provider",
+			baseUrl: INDIVIDUAL_BASE_URL,
+			auth: {
+				apiKey: {
+					name: "Copilot token",
+					resolve: async ({ credential }) =>
+						credential?.key ? { auth: { apiKey: credential.key }, source: "explicit token" } : undefined,
+				},
+				oauth: {
+					name: "Copilot OAuth",
+					login: async () => {
+						throw new Error("unused");
+					},
+					refresh: async (credential) => credential,
+					toAuth: async (credential) => ({
+						apiKey: credential.access,
+						baseUrl: ENTERPRISE_BASE_URL,
+					}),
+				},
+			},
+			getModels: () => [catalogModel],
+			stream: (requestModel) => respond(requestModel),
+			streamSimple: (requestModel) => respond(requestModel),
+		};
+
+		await harness.authStorage.modify(catalogModel.provider, async () => ({
+			type: "oauth",
+			access: "enterprise-token",
+			refresh: "refresh-token",
+			expires: Date.now() + 60 * 60_000,
+		}));
+		const modelRuntime = harness.session.modelRuntime;
+		modelRuntime.registerNativeProvider(provider);
+		await modelRuntime.refresh({ allowNetwork: false, providers: [catalogModel.provider] });
+		harness.session.agent.streamFunction = (model, context, options) =>
+			modelRuntime.streamSimple(model, context, options);
+
+		await harness.session.compact();
+
+		expect(requestBaseUrl).toBe(ENTERPRISE_BASE_URL);
+	});
+});