You are only capable of regenerating health when you are standing still in one place, resting (or searching). Continuing to move around the level or fight things does not allow you to passively heal.

Remove the Luck component of searching for secret doors and passages. Specifically, change the rnl() calls that allow a search to fail into rn2() calls, which have no Luck bias.

Rangers have a special bonus towards searching for pits.

When standing on a (not known untrapped) container and using the search command, prompt the player to check for traps on the container. Search normally if they say no.

When multiple-turn searching, stop when a new monster enters your field of vision.

Searching finds everything in your range, but is an occupation that takes multiple turns. The s command by default will take some constant number of turns (somewhere from 10-20) and will either tell you about all the hidden things around you or tell you that there is nothing interesting; you can specify a numeric prefix to search for less than that if you want.

A way to search for hidden passages behind a boulder you are pushing.