feat: user config api key (#569)

Adds support for reading OPENAI_API_KEY (and other variables) from a
user‑wide dotenv file (~/.codex.config). Precedence order is now:
  1. explicit environment variable
  2. project‑local .env (loaded earlier)
  3. ~/.codex.config

Also adds a regression test that ensures the multiline editor correctly
handles cases where printable text and the CSI‑u Shift+Enter sequence
arrive in the same input chunk.

House‑kept with Prettier; removed stray temp.json artifact.

codex-cli/src/utils/config.ts

@@ -11,11 +11,37 @@ import type { FullAutoErrorMode } from "./auto-approval-mode.js";
 import { AutoApprovalMode } from "./auto-approval-mode.js";
 import { log } from "./logger/log.js";
 import { providers } from "./providers.js";
+import { config as loadDotenv } from "dotenv";
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from "fs";
 import { load as loadYaml, dump as dumpYaml } from "js-yaml";
 import { homedir } from "os";
 import { dirname, join, extname, resolve as resolvePath } from "path";
 
+// ---------------------------------------------------------------------------
+// User‑wide environment config (~/.codex.env)
+// ---------------------------------------------------------------------------
+
+// Load a user‑level dotenv file **after** process.env and any project‑local
+// .env file (loaded via "dotenv/config" in cli.tsx) are in place.  We rely on
+// dotenv's default behaviour of *not* overriding existing variables so that
+// the precedence order becomes:
+//   1. Explicit environment variables
+//   2. Project‑local .env (handled in cli.tsx)
+//   3. User‑wide ~/.codex.env (loaded here)
+// This guarantees that users can still override the global key on a per‑project
+// basis while enjoying the convenience of a persistent default.
+
+// Skip when running inside Vitest to avoid interfering with the FS mocks used
+// by tests that stub out `fs` *after* importing this module.
+const USER_WIDE_CONFIG_PATH = join(homedir(), ".codex.env");
+
+const isVitest =
+  typeof (globalThis as { vitest?: unknown }).vitest !== "undefined";
+
+if (!isVitest) {
+  loadDotenv({ path: USER_WIDE_CONFIG_PATH });
+}
+
 export const DEFAULT_AGENTIC_MODEL = "o4-mini";
 export const DEFAULT_FULL_CONTEXT_MODEL = "gpt-4.1";
 export const DEFAULT_APPROVAL_MODE = AutoApprovalMode.SUGGEST;
@@ -117,7 +143,7 @@ export type StoredConfig = {
 // propagating to existing users until they explicitly set a model.
 export const EMPTY_STORED_CONFIG: StoredConfig = { model: "" };
 
-// Pre‑stringified JSON variant so we don’t stringify repeatedly.
+// Pre‑stringified JSON variant so we don't stringify repeatedly.
 const EMPTY_CONFIG_JSON = JSON.stringify(EMPTY_STORED_CONFIG, null, 2) + "\n";
 
 export type MemoryConfig = {

codex-cli/tests/user-config-env.test.ts

@@ -0,0 +1,62 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { mkdtempSync, writeFileSync, rmSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+
+/**
+ * Verifies that ~/.codex.env is parsed (lowest‑priority) when present.
+ */
+
+describe("user‑wide ~/.codex.env support", () => {
+  const ORIGINAL_HOME = process.env["HOME"];
+  const ORIGINAL_API_KEY = process.env["OPENAI_API_KEY"];
+
+  let tempHome: string;
+
+  beforeEach(() => {
+    // Create an isolated fake $HOME directory.
+    tempHome = mkdtempSync(join(tmpdir(), "codex-home-"));
+    process.env["HOME"] = tempHome;
+
+    // Ensure the env var is unset so that the file value is picked up.
+    delete process.env["OPENAI_API_KEY"];
+
+    // Write ~/.codex.env with a dummy key.
+    writeFileSync(
+      join(tempHome, ".codex.env"),
+      "OPENAI_API_KEY=my-home-key\n",
+      {
+        encoding: "utf8",
+      },
+    );
+  });
+
+  afterEach(() => {
+    // Cleanup temp directory.
+    try {
+      rmSync(tempHome, { recursive: true, force: true });
+    } catch {
+      // ignore
+    }
+
+    // Restore original env.
+    if (ORIGINAL_HOME !== undefined) {
+      process.env["HOME"] = ORIGINAL_HOME;
+    } else {
+      delete process.env["HOME"];
+    }
+
+    if (ORIGINAL_API_KEY !== undefined) {
+      process.env["OPENAI_API_KEY"] = ORIGINAL_API_KEY;
+    } else {
+      delete process.env["OPENAI_API_KEY"];
+    }
+  });
+
+  it("loads the API key from ~/.codex.env when not set elsewhere", async () => {
+    // Import the config module AFTER setting up the fake env.
+    const { getApiKey } = await import("../src/utils/config.js");
+
+    expect(getApiKey("openai")).toBe("my-home-key");
+  });
+});