What's a file named 'hl3.txt' doing in Dota 2's latest update?

Hl3

Um, what's this, Valve? SteamDB noticed some interesting new files added to Dota 2, and we've downloaded them and verified that they exist. The files are: hl3.txt, rpg.txt, and ai_basenpc.txt.

Here's a line from hl3.txt:

string m_HelpText = "Combine Pulse Ceiling Turret"

The files, which appear to be help text for a development tool, also refer to vehicles, NPC behaviors, squad behaviors, ziplines, and quests. Here's another example:

string m_HelpText = "NPCs that are in the same squad (i.e. have matching squad names) will share information about enemies, and will take turns attacking and covering each other."

Are these just some old files that were misplaced and have nothing to do with anything, or do they have to do with Dota 2? Or are they actual files related to the development of Half-Life 3? Here are the files so you can look for yourself: hl3.txt / rpg.txt / ai_basenpc.txt.

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