Feature request: Add `preserve_comment_indents` option to keep manual comment column alignment

[d-enk]

yamlfmt version

yamlfmt 0.20.0 (Homebrew)

Is your feature request related to a problem? Please describe.

Yes. Currently yamlfmt always normalizes the spacing before line comments according to the pad_line_comments setting.
When developers manually align comments in columns (a very common practice in configuration files, Ansible roles, Kubernetes manifests, documentation-style YAML, etc.), this alignment is completely destroyed.

Example:

# Before formatting (nicely aligned at column 50)
database_host: 127.0.0.1                                      # primary server
database_port: 5432                                           # default port
cache_enabled: true                                           # enable caching
debug_mode:    false                                          # disabled in production

# After yamlfmt – alignment is lost
database_host: 127.0.0.1 # primary server
database_port: 5432 # default port
cache_enabled: true # enable caching
debug_mode: false # disabled in production

Even setting pad_line_comments to a high value does not preserve large manual indents – the formatter still collapses them.

Describe the solution you’d like

Add a new boolean option in the basic formatter:

preserve_comment_indents: true|false   # default: false

When true: Indentation before # in line comments is preserved exactly as in the original file.

[braydonk]

This is a fair feature request, but it is extremely unlikely I will be able to implement it. The yaml parser I use doesn't maintain any whitespace information in the AST when parsing, and despite numerous attempts to make it do so I've never been able to (this was mostly in reference to newline-retention but this is similar).

It might somehow be possible, someone more dedicated than me might come along with a solution for it. But I've given up on ever implementing it myself.

[d-enk]

I implemented a tool for merging YAML files without losing formatting.

Simply add a prefix to such comments and then remove it.

database_host: 127.0.0.1 # COMMENT_PREFIX                     # primary server
database_port: 5432 # COMMENT_PREFIX                          # default port
cache_enabled: true # COMMENT_PREFIX                          # enable caching
debug_mode: false # COMMENT_PREFIX                            # disabled in production

It works.