fix: sanitize Claude auth subprocess environment

CHANGELOG.md

@@ -19,7 +19,7 @@
 - Keep `!usage blocks` billing-window selection and displayed times in UTC regardless of the host timezone.
 - Preserve line indentation when MCP clients read saved message history or pending messages.
 - Match the generated MCP endpoint hostname to the server's IPv4 loopback listener.
-- Strip inherited `CLAUDECODE` markers from Claude CLI subprocesses so Claudify can launch them from Claude Code-managed environments.
+- Strip inherited `CLAUDECODE` markers from Claude CLI response and authentication subprocesses so Claudify can launch them from Claude Code-managed environments.
 - Reject required prompt values that contain no non-whitespace content.
 - Match legacy MCP history channel filters exactly instead of including similarly named channels.
 - Preserve URL-only embeds returned by the MCP `fetch-messages` tool.

src/claudeAuth.ts

@@ -190,7 +190,11 @@ export class ClaudeAuthManager {
             options.loginTimeoutMs,
             DEFAULT_LOGIN_TIMEOUT_MS,
         );
-        this.env = options.env || process.env;
+        this.env = {};
+        for (const [key, value] of Object.entries(options.env || process.env)) {
+            if (key.toUpperCase() === "CLAUDECODE") continue;
+            if (value !== undefined) this.env[key] = value;
+        }
     }
 
     async getStatus(): Promise<ClaudeAuthStatus> {

tests/claudeAuth.test.mjs

@@ -80,6 +80,38 @@ test("preserves balanced delimiters within Claude login URLs", () => {
     assert.equal(extractClaudeLoginUrl(loginUrl), loginUrl);
 });
 
+test("does not pass nested Claude markers to auth subprocesses", async (t) => {
+    const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "claudify-auth-"));
+    const markerPath = path.join(tempDir, "authenticated");
+    const fakeCliPath = path.join(tempDir, "fake-claude.mjs");
+    const fixturePath = path.join(currentDir, "fixtures", "fakeClaudeAuth.mjs");
+    fs.copyFileSync(fixturePath, fakeCliPath);
+    fs.writeFileSync(markerPath, "authenticated", "utf8");
+    t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }));
+
+    const manager = new ClaudeAuthManager({
+        command: process.execPath,
+        prefixArgs: [fakeCliPath],
+        commandTimeoutMs: 2_000,
+        loginTimeoutMs: 2_000,
+        env: {
+            ...process.env,
+            CLAUDECODE: "1",
+            ClAuDeCoDe: "also-set",
+            CLAUDIFY_AUTH_TEST_MARKER: markerPath,
+            CLAUDIFY_AUTH_TEST_REQUIRE_TTY: "1",
+        },
+    });
+
+    assert.equal((await manager.getStatus()).loggedIn, true);
+    fs.unlinkSync(markerPath);
+    assert.equal(
+        await manager.startLogin("owner"),
+        "https://claude.com/cai/oauth/authorize?test=1",
+    );
+    manager.cancelLogin("owner");
+});
+
 test("runs a private login session and verifies its final status", async (t) => {
     const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "claudify-auth-"));
     const markerPath = path.join(tempDir, "authenticated");

tests/fixtures/fakeClaudeAuth.mjs

@@ -3,6 +3,11 @@ import fs from "node:fs";
 const [, , group, action] = process.argv;
 const markerPath = process.env.CLAUDIFY_AUTH_TEST_MARKER;
 
+if (Object.keys(process.env).some((key) => key.toUpperCase() === "CLAUDECODE")) {
+    process.stderr.write("Nested Claude sessions are not supported.\n");
+    process.exit(1);
+}
+
 if (!markerPath || group !== "auth") {
     process.exit(2);
 }