fix(coding-agent): treat uppercase config values as literals

closes #5661

packages/coding-agent/test/suite/regressions/5661-uppercase-header-values.test.ts

@@ -0,0 +1,91 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+import { ENV_AGENT_DIR } from "../../../src/config.ts";
+import { AuthStorage } from "../../../src/core/auth-storage.ts";
+import { ModelRegistry } from "../../../src/core/model-registry.ts";
+import { runMigrations } from "../../../src/migrations.ts";
+import { createHarness } from "../harness.ts";
+
+describe("regression #5661: uppercase models.json header values", () => {
+	const cleanups: Array<() => void> = [];
+
+	afterEach(() => {
+		while (cleanups.length > 0) {
+			cleanups.pop()?.();
+		}
+	});
+
+	function withAgentDir(agentDir: string, fn: () => void): void {
+		const previousAgentDir = process.env[ENV_AGENT_DIR];
+		process.env[ENV_AGENT_DIR] = agentDir;
+		try {
+			fn();
+		} finally {
+			if (previousAgentDir === undefined) {
+				delete process.env[ENV_AGENT_DIR];
+			} else {
+				process.env[ENV_AGENT_DIR] = previousAgentDir;
+			}
+		}
+	}
+
+	it("keeps uppercase header strings as literals during startup migrations", async () => {
+		const harness = await createHarness({ withConfiguredAuth: false });
+		cleanups.push(harness.cleanup);
+
+		const envKeys = ["CUSTOM_API_KEY", "BEARER"];
+		const savedEnv: Record<string, string | undefined> = {};
+		for (const key of envKeys) {
+			savedEnv[key] = process.env[key];
+			process.env[key] = `env-${key}`;
+		}
+		cleanups.push(() => {
+			for (const key of envKeys) {
+				if (savedEnv[key] === undefined) {
+					delete process.env[key];
+				} else {
+					process.env[key] = savedEnv[key];
+				}
+			}
+		});
+
+		const modelsPath = join(harness.tempDir, "models.json");
+		writeFileSync(
+			modelsPath,
+			`${JSON.stringify(
+				{
+					providers: {
+						"my-provider": {
+							baseUrl: "https://example.com/v1",
+							apiKey: "CUSTOM_API_KEY",
+							api: "openai-completions",
+							headers: { Authorization: "BEARER" },
+							models: [{ id: "my-model" }],
+						},
+					},
+				},
+				null,
+				2,
+			)}\n`,
+			"utf-8",
+		);
+
+		withAgentDir(harness.tempDir, () => runMigrations(harness.tempDir));
+
+		const migrated = JSON.parse(readFileSync(modelsPath, "utf-8")) as {
+			providers: Record<string, { apiKey?: string; headers?: Record<string, string> }>;
+		};
+		expect(migrated.providers["my-provider"]?.apiKey).toBe("CUSTOM_API_KEY");
+		expect(migrated.providers["my-provider"]?.headers?.Authorization).toBe("BEARER");
+
+		const registry = ModelRegistry.create(AuthStorage.create(join(harness.tempDir, "auth.json")), modelsPath);
+		const model = registry.find("my-provider", "my-model");
+		expect(model).toBeDefined();
+		expect(await registry.getApiKeyAndHeaders(model!)).toMatchObject({
+			ok: true,
+			apiKey: "CUSTOM_API_KEY",
+			headers: { Authorization: "BEARER" },
+		});
+	});
+});