[SahAssar]

A 12kLOC YML sounds like it's always going to be a pain in the butt, but the specific problem you mention should be solvable by any editor that can collapse blocks, right? Most editors I've used (vscode, vim, phpstorm, intellij, even notepad++) have that feature built in or supplied by a pretty standard plugin.

[chinigo]

Yeah code folding works for the visual scrub, but it's the "search within" feature that's missing.

An example of my common use case is digging through a Bosh manifest file for a resource with a particular name, then finding, say, the VM type associated with that resource. The name and vm_type fields may be separated by hundreds of lines (it's a machine-generated file that does not retain element order), but they're siblings of each other.

In vim, I could land on the first { and then hit:

  v% (extend selection to matching delimiter)
  /\%Vvmtype: (to search for "vmtype:" within the selection).

In IntelliJ I could similarly extend a selection between delimiters and then search within it.

It's absolutely correct that this is a tooling problem. You could imagine a YML plugin for IntelliJ or vim smart enough to offer a motion for "select all the children of this block," but AFAICT no such tool exists.