indentgrep

#!/usr/bin/perl

use v5.28;
use warnings qw( FATAL all );

@ARGV or die "Usage: $0 PATTERN [FILES...]";

my $pattern = shift @ARGV;
$pattern = qr/$pattern/o;

my @where;
my $wi = 0;

while(<>) {
    s/\s*\z//;
    length or next;
    my $indent = /^(\s+)/ && $1;
    while( @where && $where[-1] =~ /^$indent/ ) {
        pop @where;
        $wi = @where if $wi > @where;
    }
    push @where, $_;
    if( /$pattern/ ) {
        say $_ for @where[ $wi .. $#where ];
        $wi = @where;
    }
} continue {
    if( eof ) {
        @where = ();
        $wi = 0;
    }
}