ArcaneDesk App

ArcaneDesk is a desktop app for DMs who run FVTT, bundling Foundry VTT installation, management, and assistive AI agents into one installer, with support for Windows and macOS.

Prerequisites

  • Windows 10/11 or macOS
  • A valid Foundry VTT license
  • Model service — pick one:
    • Bring your own model API key (BYOK), plus an optional separate speech recognition key
    • Or subscribe to the official Arcane Spark Key

Core capabilities

  • One-click install: download, install, and runtime fully managed. No Node, no command line — ready to run a session out of the box.
  • Assisted prep: the content agent preps alongside you — modules and world lore organized, character sheets synced, everything ready before the session starts.
  • Automated combat: the combat agent runs the turn flow — initiative, actions, and resolution advance on their own while you narrate the scene.

Two modes

Prep mode (Prepping)

Prep mode home screen

Prep mode is designed around session preparation and does three things:

  1. Prep content work (file read/write): inside the current prep workspace (workspaces/prep) — read and write Markdown notes (plot outlines, house rules, campaign settings); design NPCs, locations, encounters, and items; build an Obsidian vault from module PDFs and search stories, characters, and locations.
  2. FVTT install & ops: driven by the matching skills — install/repair/upgrade/migrate Foundry VTT 13 (handling ZIP/EXE/DMG, the dnd5e system, and Arcane modules); daily ops such as starting/stopping the server, reading logs, troubleshooting port 30000 conflicts, switching worlds, and handling options.json.lock.
  3. FVTT world sync: with the GM panel open on the right, it calls Foundry’s public Document API to sync the Actors, Items, JournalEntries, Scenes, etc. you ask for into the current world — with pre-write confirmation (game.ready + isGM), dedupe, and read-back verification. Nothing gets written carelessly.

Skill files (loaded automatically when needed):

Skill Scenario
arcane-fvtt-ops Server start/stop, logs, ports, world switching
arcane-fvtt-setup Fresh install / upgrade / migration of FVTT
arcane-module-reader Module PDF → Obsidian vault
arcane-actor-images Portrait and token image maintenance

Constraints:

  • It can only read and write files inside the current workspace; anything outside is handed to you for manual action
  • PowerShell 5.1 on Windows, Bash on macOS — you will never be asked to install Node or a package manager
  • Real-time combat operations (turn advancement, action execution) are out of prep scope — switch to combat mode for those

Combat mode

Combat mode home screen

Combat mode is ArcaneDesk’s embedded real-time combat copilot, facing the DM directly — a completely different toolset from prep mode. Its core job: turning your spoken “who does what to whom” into real combat operations in the Foundry world — resolving hits, rolling damage, advancing turns.

Tools it uses:

Tool Purpose
combat_battle_context Battle handbook: the catalog of actions available in this battle (attacks/spells/features), read once per battle
combat_turn_context Live turn state: whose turn it is, which actions are available, target HP, etc. — required reading before every decision
combat_execute_turn Submits an action (actions + targets + inputs) and returns a four-state receipt
world_status Read-only world information
foundry_open / browser_evaluate Opens the panel, bounded page diagnostics

Key rules (very different from prep mode):

  • Trust tools, not memory, for live state: the DM and players may drag tokens, change HP, or roll dice at any time, so the turn context is re-read before every command; anything in the conversation history is treated as stale.
  • No tactical refereeing: distance, range, positioning, and movement legality are judged by the execution layer and the DM; movement itself is done manually by the DM.
  • Advantage/disadvantage and spell-slot levels are only passed when you explicitly say so — never inferred tactically.
  • Actions are executed and turns advanced only when the DM explicitly asks; by default it executes without advancing.
  • Execution receipts come in four states: completed / rejected / partial / indeterminate. partial and indeterminate are never retried — they are handed to the DM for adjudication.