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

[tianyicui]

Summary

• Expose VS Code Server's --reconnection-grace-time CLI argument through code-server, allowing users to configure how long the server waits for a disconnected client to reconnect before cleaning up the session
• Add support for $CS_RECONNECTION_GRACE_TIME environment variable and config.yaml setting
• The underlying VS Code Server (1.107+) already implements this flag in serverEnvironmentService.ts; code-server just wasn't passing it through

Motivation

When a client machine sleeps (e.g., overnight), the WebSocket connection drops. VS Code Server's default 3-hour reconnection grace time expires, the server discards the reconnection token, and the user is forced to "Reload Window" on wake. Users who want longer grace periods currently have no way to configure this.

Fixes #7665

Changes

• src/node/cli.ts: Added reconnection-grace-time to UserProvidedCodeArgs interface, options object, and setDefaults() (env var support via $CS_RECONNECTION_GRACE_TIME)
• test/unit/node/cli.test.ts: Added test for the new flag in the "parse all options" test and a dedicated env var test

Usage

# CLI flag (value in seconds, e.g., 30 days)
code-server --reconnection-grace-time 2592000

# Environment variable
CS_RECONNECTION_GRACE_TIME=2592000 code-server

# config.yaml
reconnection-grace-time: 2592000

Test plan

• Existing CLI parser tests pass (68/68)
• New test: --reconnection-grace-time is parsed correctly from CLI
• New test: $CS_RECONNECTION_GRACE_TIME env var is picked up in setDefaults()
• Manual: verify the flag is passed through to VS Code Server and sessions survive long disconnects

🤖 Generated with Claude Code