feat: expose --reconnection-grace-time CLI flag

Pass through VS Code Server's --reconnection-grace-time argument,
allowing users to configure how long the server waits for a
disconnected client to reconnect before cleaning up the session.

This is useful for users whose client machines sleep overnight, causing
the default 3-hour grace period to expire and forcing a "Reload Window"
on wake. The flag can also be set via $CS_RECONNECTION_GRACE_TIME env
var or in config.yaml.

Fixes #7665

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: tianyicui

src/node/cli.ts

@@ -52,6 +52,7 @@ export interface UserProvidedCodeArgs {
   "disable-workspace-trust"?: boolean
   "disable-getting-started-override"?: boolean
   "disable-proxy"?: boolean
+  "reconnection-grace-time"?: string
   "session-socket"?: string
   "cookie-suffix"?: string
   "link-protection-trusted-domains"?: string[]
@@ -315,6 +316,12 @@ export const options: Options<Required<UserProvidedArgs>> = {
     type: "number",
     description: "Timeout in seconds to wait before shutting down when idle.",
   },
+  "reconnection-grace-time": {
+    type: "string",
+    description:
+      "Override the reconnection grace time in seconds. Clients who disconnect for longer than this duration will need to \n" +
+      "reload the window. Defaults to 10800 (3 hours).",
+  },
 }
 
 export const optionDescriptions = (opts: Partial<Options<Required<UserProvidedArgs>>> = options): string[] => {
@@ -632,6 +639,10 @@ export async function setDefaults(cliArgs: UserProvidedArgs, configArgs?: Config
     args["github-auth"] = process.env.GITHUB_TOKEN
   }
 
+  if (process.env.CS_RECONNECTION_GRACE_TIME) {
+    args["reconnection-grace-time"] = process.env.CS_RECONNECTION_GRACE_TIME
+  }
+
   if (process.env.CODE_SERVER_IDLE_TIMEOUT_SECONDS) {
     if (isNaN(Number(process.env.CODE_SERVER_IDLE_TIMEOUT_SECONDS))) {
       logger.info("CODE_SERVER_IDLE_TIMEOUT_SECONDS must be a number")

test/unit/node/cli.test.ts

@@ -48,6 +48,7 @@ describe("parser", () => {
     delete process.env.PASSWORD
     delete process.env.CS_DISABLE_FILE_DOWNLOADS
     delete process.env.CS_DISABLE_GETTING_STARTED_OVERRIDE
+    delete process.env.CS_RECONNECTION_GRACE_TIME
     delete process.env.VSCODE_PROXY_URI
     delete process.env.CS_DISABLE_PROXY
     console.log = jest.fn()
@@ -115,6 +116,8 @@ describe("parser", () => {
 
           ["--session-socket", "/tmp/override-code-server-ipc-socket"],
 
+          ["--reconnection-grace-time", "86400"],
+
           ["--host", "0.0.0.0"],
           "4",
           "--",
@@ -151,6 +154,7 @@ describe("parser", () => {
       version: true,
       "bind-addr": "192.169.0.1:8080",
       "session-socket": "/tmp/override-code-server-ipc-socket",
+      "reconnection-grace-time": "86400",
       "abs-proxy-base-path": "/codeserver/app1",
       "skip-auth-preflight": true,
     })
@@ -457,6 +461,19 @@ describe("parser", () => {
     })
   })
 
+  it("should use env var CS_RECONNECTION_GRACE_TIME", async () => {
+    process.env.CS_RECONNECTION_GRACE_TIME = "86400"
+    const args = parse([])
+    expect(args).toEqual({})
+
+    const defaultArgs = await setDefaults(args)
+    expect(defaultArgs).toEqual({
+      ...defaults,
+      "reconnection-grace-time": "86400",
+    })
+    delete process.env.CS_RECONNECTION_GRACE_TIME
+  })
+
   it("should error if password passed in", () => {
     expect(() => parse(["--password", "supersecret123"])).toThrowError(
       "--password can only be set in the config file or passed in via $PASSWORD",