fix hitory file path

[ko1]

• Set default of CONFIG[:history_file] as nil, and ignore it if it is nil.
• Respect CONFIG[:history_file] even if the path doesn't exists.
• Respect ~/.rdbg_history if exists for compatibility.
• Use XDG_STATE_HOME if there is no configuration about history file.

[cloudbees-smart-tests]

❌ Tests Failed

✖️no tests failed ✔️540 tests passed(140 flakes)

[ko1]

#1031

[Copilot]

Pull Request Overview

This PR refactors how the history file path is determined, making the default configurable via CONFIG[:history_file], preserving legacy ~/.rdbg_history, and falling back to $XDG_STATE_HOME/rdbg/history.

• Change default history_file config value from "~/.rdbg_history" to nil
• Rewrite history_file method in console.rb to respect config, legacy path, then XDG state directory
• Update README to document the new default path

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
lib/debug/console.rb	Revised history_file logic to handle nil, legacy file, and XDG state path
lib/debug/config.rb	Set default history_file to nil
README.md	Updated default history_file documentation

Comments suppressed due to low confidence (1)

lib/debug/console.rb:153

• Add tests for the new history_file logic: nil config, legacy ~/.rdbg_history, and XDG state directory fallback.

def history_file

[jasonkarns]

This is great! Do you think we need to document the fallback when XDG_STATE_HOME is unset? This PR does use the basedir specification's default (yay!), but that behavior isn't documented. Would it be welcome if I open a PR to modify the docs to that effect?

[ko1]

RUBY_DEBUG_HISTORY_FILE (history_file): history file (default: $XDG_STATE_HOME/rdbg/history)

is written. not enough?

[jasonkarns]

I think the confusion is for users who have never heard of XDG before and don't have XDG_STATE_HOME env var set. They would have no idea where to find the file.

The code itself shows the fallback (~/.local/state) when XDG_STATE_HOME is unset, but that's not indicated in the comments/docs.

I would suggest using bash's own expansion syntax to indicate the env var's fallback in-line:

RUBY_DEBUG_HISTORY_FILE (history_file): history file (default: ${XDG_STATE_HOME-~/.local/state}/rdbg/history)

This way, they don't need to google XDG_STATE_HOME to find what its default value is.

Should I PR this?
PR open here #1148 so discussion can continue there instead of on this already-merged PR.