dcc-mcp-epic

Local-first, typed Epic Games Launcher / Fab / Unreal project adapter for DCC-MCP. It follows the LiquiGen adapter pattern: exact runtime binding, versioned commands, read-before-write policy, resumable operation results, and no generic UI automation fallback.

Current 0.2 boundary

• Installed UE inventory: available, read-only, from Epic .item manifests.
• UE installation integrity checks: available, read-only, verifies the editor binary.
• UE 5.5 project verification: available, read-only.
• UE install/update: plan-only; returns human_required until a supported native Launcher bridge is verified.
• Exact Launcher UI actions: available through a declared dcc-cua hook for bounded click/key/scroll/text actions. The request requires a live PID/HWND/executable tuple, a known input backend, and post-action evidence; semantic selectors and generic automation are rejected.
• dcc-cua preflight: available as a read-only cua-preflight CLI/MCP tool. It checks the official runtime, ping, visual diagnostics, and exact window binding before any UI action; degraded diagnostics are reported as blocked instead of being retried as input.
• Fab search: read-only local index search. Fab download/export are available only through a declared user-owned hook; the adapter never automates login, CAPTCHA, 2FA, purchase, or license acceptance.
• Free Fab catalog: available through a read-only official/native provider hook; the adapter does not scrape the storefront or handle credentials.
• Local Fab library index: available, read-only, when Epic's listings_v1.db exists.
• Multi-source Fab inventory: available, read-only, merges explicitly selected indexes and can discover listings_v1.db below caller-approved roots.
• Fab Add to My Library: available through a declared user-owned hook for explicitly-free listings, with bounded batch support (up to 100 IDs), exact optional Launcher identity, and mandatory post-action ownership evidence.
• Fab library sync: available through a scoped user-owned hook keyed to the Launcher PID and approved cache/index roots; the adapter never edits Epic's databases directly.
• Free asset sync: one confirmation-gated, bounded workflow can add up to 100 explicitly-free listings to My Library, download compatible formats, verify local state, and optionally import into a scoped UE project. It advertises cua_calls_expected: 0; the provider hook performs native/API work and returns per-asset evidence.
• Fab asset detail: read-only listing metadata plus cache evidence for one asset, available through a typed hook.
• Fab download status: available, read-only, re-reads ownership, path and cache evidence after a user-owned download hook.
• Fab batch download status: bounded (up to 100 IDs), merges multiple local indexes and returns per-asset evidence through a typed hook.
• Cached Fab import: available for already-owned/downloaded Unreal Content; dry-run, explicit confirmation, VaultCache-root enforcement, no-overwrite behavior, and per-file provenance hashes are built in. FBX/GLTF/OBJ/USD source downloads with textures are also preserved for Unreal's importer.
• Generic CUA fallback: disabled.
• Self-owned hook bridge: supported through the fixed epic.hook.v1 manifest contract, with dry-run and explicit confirmation as defaults.
• Typed Fab download request: policy-checks a free, owned asset and dispatches a fixed payload to a declared user-owned hook; completion still needs fresh library/project evidence.
• Local Fab search: read-only full-text/category/format filters across merged indexes, with owned/downloaded-only selectors.
• Typed engine requests: install, update, download, verify, and launch hooks expose scoped payloads while preserving read-before-write plans.
• Typed Fab/project requests: export, one-asset import, batch import, and project import hooks enforce explicit roots, formats, and confirmation.
• Typed UE-native Fab batch Add to Project: up to 100 free, owned IDs are dispatched to a hook that must execute one official Add to Project action per asset and return per-asset evidence.
• Bounded batch download request: up to 100 free, owned asset IDs can be sent to one user-owned hook, with per-asset verification required afterwards. UE-native content is rejected for this operation because Fab Launcher uses Add to Project instead; use fab-add-to-project-request or the bounded fab-add-to-project-batch-request for UE content.
• Hook contract introspection: hook-contract / epic_hook_contract returns the stable epic.hook.v1 operation list, required fields, mutation flags, and confirmation defaults for self-owned integrations. Generic hook-invoke calls are rejected when a required field is missing.
• Read-only hook requests: Launcher status, Fab search/library/source/detail reads, single/batch download status, project import inventory, and the Fab callback listener probe are available as typed *_request MCP tools and CLI commands. Each request includes the local evidence plan and reports no mutation.
• CUA minimization: prefer fab.catalog_free.request for discovery and fab.free_assets_sync.request for a single provider job. launcher.action remains a bounded dcc-cua fallback for custom-rendered UI only.
• Runtime selection: runtime-doctor prefers a verified DCC-MCP sidecar when a compatible Python/MCP environment exists and otherwise selects the shared PyOxidizer bundle. Unreal's embedded Python is never reused.

Bundled agent skills

The adapter now ships two discoverable, progressive-loading skills under src/dcc_mcp_epic/skills/:

• $epic-fab — exact-window dcc-cua preflight, local Fab index discovery and search, bounded free-asset sync planning/execution, and project provenance inventory.
• $epic-unreal — UE project verification, installed-engine inventory, and a read-only Unreal Editor launch plan.

Their SKILL.md, tools.yaml, scripts, and OpenAI interface metadata are included in wheels and source distributions. Use dcc-mcp-cli search and dcc-mcp-cli load-skill to discover/load them when dcc-mcp-core is installed; the direct dcc-mcp-epic FastMCP tools remain available independently. Fab mutation tools default to execute=false and preserve the official-provider, human-authentication boundary.

Built-in Fab worker

The package includes a language-neutral epic.hook.v1 worker. It performs local Fab/library/status/inventory reads without UI automation and returns a typed capability_unavailable result for account/download mutations until a user-owned official/native provider is configured. This keeps completion claims honest while avoiding CUA loops and private Launcher hooks.

Generate a manifest using the same Python runtime that will execute the adapter:

uv run dcc-mcp-epic-cli fab-worker-manifest --output .\fab-worker.json
uv run dcc-mcp-epic-cli hook-probe .\fab-worker.json

To delegate account/library/download operations, set DCC_MCP_EPIC_FAB_PROVIDER_COMMAND to a JSON array whose first item is an existing absolute executable. The provider receives the same fixed stdin request and must return epic.hook.v1 JSON with a typed state and per-asset evidence. DCC_MCP_EPIC_FAB_CATALOG_JSON may point to a caller-maintained catalog snapshot for offline free-catalog filtering; snapshot entries must explicitly carry price: 0 and free_listing: true.

Local build and tests

uv sync --extra dev
uv run pytest
uv run ruff check .
uv build

Test the new interface against this machine

uv run dcc-mcp-epic-cli capabilities
uv run dcc-mcp-epic-cli runtime-doctor
uv run dcc-mcp-epic-cli cua-preflight `
  --pid <EpicLauncherPID> --hwnd <EpicLauncherHWND> `
  --executable 'C:\Program Files\Epic Games\Launcher\Portal\Binaries\Win64\EpicGamesLauncher.exe'
uv run dcc-mcp-epic-cli hook-contract
uv run dcc-mcp-epic-cli engines
uv run dcc-mcp-epic-cli project-verify P:\game-test\ue-arpg\RiftKidsARPG.uproject
uv run dcc-mcp-epic-cli engine-verify
uv run dcc-mcp-epic-cli fab-library
uv run dcc-mcp-epic-cli fab-library-sources `
  --search-root C:\ProgramData\Epic `
  --search-root C:\Users\hallong\Downloads\Video `
  --search-root F:\UE\EpicGamesLauncher
uv run dcc-mcp-epic-cli fab-download-status <asset-id> `
  --database F:\UE\EpicGamesLauncher\VaultCache\FabLibrary\listings_v1.db `
  --cache-root F:\UE\EpicGamesLauncher\VaultCache
uv run dcc-mcp-epic-cli fab-asset-inspect b8ff3ab4-0e81-4335-bbf0-fea15f6fcdfc
uv run dcc-mcp-epic-cli fab-asset-detail-request <asset-id> `
  --hook-manifest C:\path\hook.json --search-root C:\ProgramData\Epic
uv run dcc-mcp-epic-cli fab-download-request <asset-id> P:\game-test\ue-arpg `
  --allowed-root P:\game-test\ue-arpg --hook-manifest C:\path\hook.json `
  --owned
uv run dcc-mcp-epic-cli fab-import-all-cached P:\game-test\ue-arpg `
  --allowed-root P:\game-test\ue-arpg `
  --database C:\ProgramData\Epic\EpicGamesLauncher\VaultCache\FabLibrary\listings_v1.db `
  --database F:\UE\EpicGamesLauncher\VaultCache\FabLibrary\listings_v1.db `
  --cache-root C:\ProgramData\Epic\EpicGamesLauncher\VaultCache `
  --cache-root F:\UE\EpicGamesLauncher\VaultCache
uv run dcc-mcp-epic-cli fab-project-inventory P:\game-test\ue-arpg `
  --allowed-root P:\game-test\ue-arpg
uv run dcc-mcp-epic-cli fab-launcher-probe --editor-pid <UnrealEditorPID>
uv run dcc-mcp-epic-cli fab-launcher-status-probe --launcher-pid <EpicLauncherPID>
uv run dcc-mcp-epic-cli engine-update-plan 5.5
uv run dcc-mcp-epic-cli engine-download-request 5.5 `
  --hook-manifest C:\path\hook.json --install-root F:\UE\UE_5.5 `
  --allowed-root F:\UE
uv run dcc-mcp-epic-cli fab-search Arrow `
  --search-root C:\ProgramData\Epic --owned-only --downloaded-only
uv run dcc-mcp-epic-cli fab-search-request Arrow `
  --hook-manifest C:\path\hook.json --search-root C:\ProgramData\Epic
uv run dcc-mcp-epic-cli fab-library-request `
  --hook-manifest C:\path\hook.json --database C:\path\listings_v1.db
uv run dcc-mcp-epic-cli fab-add-to-library-request <asset-id> `
  --hook-manifest C:\path\hook.json --free-listing `
  --launcher-pid <EpicLauncherPID> --launcher-hwnd <EpicLauncherHWND> `
  --launcher-executable C:\Program Files\Epic Games\Launcher\Portal\Binaries\Win64\EpicGamesLauncher.exe
uv run dcc-mcp-epic-cli fab-add-to-library-batch-request `
  <asset-id-1> <asset-id-2> --hook-manifest C:\path\hook.json `
  --free-listing --launcher-pid <EpicLauncherPID> `
  --launcher-hwnd <EpicLauncherHWND> `
  --launcher-executable C:\Program Files\Epic Games\Launcher\Portal\Binaries\Win64\EpicGamesLauncher.exe
uv run dcc-mcp-epic-cli fab-catalog-free-request "environment" `
  --hook-manifest C:\path\hook.json --category Environment `
  --format unreal-engine --limit 20
uv run dcc-mcp-epic-cli fab-free-assets-sync-request C:\path\free-assets.json `
  --allowed-root P:\game-test\ue-arpg --hook-manifest C:\path\hook.json `
  --mode library_download_and_project `
  --project-path P:\game-test\ue-arpg
uv run dcc-mcp-epic-cli fab-library-sync-request `
  --launcher-pid <EpicLauncherPID> --allowed-root F:\UE `
  --hook-manifest C:\path\hook.json `
  --database F:\UE\EpicGamesLauncher\VaultCache\FabLibrary\listings_v1.db `
  --cache-root F:\UE\EpicGamesLauncher\VaultCache
uv run dcc-mcp-epic-cli fab-download-status-request <asset-id> `
  --hook-manifest C:\path\hook.json --database C:\path\listings_v1.db
uv run dcc-mcp-epic-cli fab-download-status-batch-request `
  <asset-id-1> <asset-id-2> --hook-manifest C:\path\hook.json `
  --search-root C:\ProgramData\Epic --cache-root C:\ProgramData\Epic\EpicGamesLauncher\VaultCache
uv run dcc-mcp-epic-cli fab-import-inventory-request P:\game-test\ue-arpg `
  --allowed-root P:\game-test\ue-arpg --hook-manifest C:\path\hook.json
uv run dcc-mcp-epic-cli fab-launcher-status-request `
  --launcher-pid <EpicLauncherPID> --hook-manifest C:\path\hook.json
uv run dcc-mcp-epic-cli launcher-action-request `
  --pid <EpicLauncherPID> --hwnd <EpicLauncherHWND> `
  --executable C:\Program Files\Epic Games\Launcher\Portal\Binaries\Win64\EpicGamesLauncher.exe `
  --version <LauncherVersion> `
  --action-json '{"action":"keypress","keys":["ESC"],"input_backend_id":"windows.post_message_key.v1"}' `
  --hook-manifest C:\path\hook.json
uv run dcc-mcp-epic-cli fab-download-batch-request P:\game-test\ue-arpg `
  <asset-id-1> <asset-id-2> --allowed-root P:\game-test\ue-arpg `
  --hook-manifest C:\path\hook.json --owned
uv run dcc-mcp-epic-cli fab-add-to-project-request <asset-id> P:\game-test\ue-arpg `
  --allowed-root P:\game-test\ue-arpg --hook-manifest C:\path\hook.json --owned
uv run dcc-mcp-epic-cli fab-add-to-project-batch-request P:\game-test\ue-arpg `
  <asset-id-1> <asset-id-2> --allowed-root P:\game-test\ue-arpg `
  --hook-manifest C:\path\hook.json --owned
uv run dcc-mcp-epic-cli fab-export-request <asset-id> P:\game-test\ue-arpg\Exports `
  --allowed-root P:\game-test\ue-arpg --hook-manifest C:\path\hook.json --owned
uv run python scripts/probe_mcp.py

Start the MCP stdio server with:

uv run dcc-mcp-epic

When the shared DCC-MCP server is installed, expose the same adapter through its HTTP/gateway bridge without installing another gateway process:

dcc-mcp-server translate --stdio "uv run dcc-mcp-epic" --app-type epic `
  --host 127.0.0.1 --port 0 --gateway-port 0 --no-register

The adapter is not affiliated with or endorsed by Epic Games. Epic Launcher, Fab, UE, and associated content remain subject to their own terms and licenses.