VM Unity MCP

VM Unity MCP is an independently maintained Unity Editor MCP bridge published by VM233. It provides structured, queue-safe tools for scenes, assets, UI Toolkit, packages, builds, tests, project-defined workflows, and Editor diagnostics.

This project was originally derived from AnkleBreaker Studio's Unity MCP Plugin and retains its full license and attribution requirements. Powered by AnkleBreaker MCP. VM Unity MCP now develops and releases from a standalone repository rather than a GitHub fork.

Related original projects:

• Original Unity MCP Plugin
• Unity MCP Server

Install

In Unity Package Manager, choose Add package from git URL... and enter:

https://github.com/VM233/VMUnityMCP.git

For a reproducible project dependency, pin a specific commit:

https://github.com/VM233/VMUnityMCP.git#<commit-hash>

The bridge runs inside the Unity Editor on 127.0.0.1, usually port 7890. Verify it with:

http://127.0.0.1:7890/api/ping

Capabilities

Area	MCP tool name	HTTP route	Purpose
Fallback entrypoint	unity_advanced_execute	advanced/execute	Fallback route for commands that do not have a concrete tool yet. Prefer route-specific unity_* tools first.
MCP diagnostics	unity_mcp_health	mcp/health	Inspect bridge state, queue state, sessions, process memory, recent actions, and slow requests.
MCP diagnostics	unity_mcp_set_autostart	mcp/set-autostart	Enable or disable bridge auto-start for the current Unity Editor instance.
Editor stability	unity_wait_editor_idle	wait/editor-idle	Wait for compilation, package refresh, domain reload, and asset import to settle before issuing the next command.
Testing	unity_testing_list_tests	testing/list-tests	List discoverable EditMode or PlayMode tests with filters.
Testing	unity_testing_run_tests	testing/run-tests	Start a Unity Test Runner job.
Testing	unity_testing_get_job	testing/get-job	Poll test progress and detailed results.
Package testing	unity_testing_run_package_tests	testing/run-package-tests	Temporarily enable Git package tests, run them across domain reloads, and restore the package manifest exactly.
Package testing	unity_testing_get_package_job	testing/get-package-job	Poll the persistent package test workflow and its final test result.
Localization	unity_localization_upsert_entry	localization/upsert-entry	Prevalidate and upsert one or more String, Smart String, or Asset Table entries with execution.mode controlling immediate or frame-batched execution.
Multi-editor safety	unity_instance_current	instance/current	Return the current Editor MCP instance identity, including project path and port.
Multi-editor safety	unity_instance_list	instance/list	List registered Editor MCP instances across open Unity projects.
Multi-editor safety	unity_instance_resolve	instance/resolve	Resolve exactly one Editor MCP instance by project path, project name, or port.
Multi-editor safety	unity_instance_assert_project	instance/assert-project	Verify that a request reached the expected Unity project.
Prefab asset editing	unity_prefab_asset_add_component	prefab-asset/add-component	Add a component after waiting for a newly compiled script type to become available; returns prefab YAML diff by default.
Prefab asset editing	unity_prefab_asset_configure_component	prefab-asset/configure-component	Ensure one component exists and atomically configure serialized properties and ObjectReferences in one prefab save.
Prefab asset editing	unity_prefab_asset_add_gameobject	prefab-asset/add-gameobject	Create a child GameObject inside a prefab asset.
Prefab asset editing	unity_prefab_asset_transaction_edit	prefab-asset/transaction-edit	Apply ordered prefab edits in one load/save transaction with execution.mode controlling immediate or frame-batched execution.
Prefab asset editing	unity_prefab_asset_instantiate_child_prefab	prefab-asset/instantiate-child-prefab	Instantiate one prefab asset as a child inside another prefab asset.
Prefab asset editing	unity_prefab_asset_move_gameobject	prefab-asset/move-gameobject	Move or reorder a GameObject inside a prefab asset without opening Prefab Mode manually.
Prefab asset editing	unity_prefab_asset_move_component	prefab-asset/move-component	Atomically move a component between GameObjects while preserving its serialized data and remapping references to the moved component.
Prefab asset editing	unity_prefab_asset_remove_component	prefab-asset/remove-component	Remove a component from a GameObject inside a prefab asset.
Prefab asset editing	unity_prefab_asset_remove_gameobject	prefab-asset/remove-gameobject	Remove a child GameObject from inside a prefab asset.
Prefab asset editing	unity_prefab_asset_set_property	prefab-asset/set-property	Set a serialized property on a component inside a prefab asset.
Prefab asset editing	unity_prefab_asset_set_reference	prefab-asset/set-reference	Set an ObjectReference property on a component inside a prefab asset.
Prefab asset search	unity_prefab_asset_find	prefab-asset/find	Find prefab children by name/path, component type, and serialized property value.
Prefab asset search	unity_prefab_asset_hierarchy	prefab-asset/hierarchy	Read a prefab asset hierarchy directly from disk.
Prefab asset search	unity_prefab_asset_get_properties	prefab-asset/get-properties	Read serialized component properties inside a prefab asset.
Scene editing	unity_scene_instantiate_prefab	scene/instantiate-prefab	Instantiate a prefab asset into the currently open scene.
Safe assets	unity_asset_refresh	asset/refresh	Start a reload-safe AssetDatabase refresh and return a refresh job ID.
Safe assets	unity_asset_get_refresh_job	asset/get-refresh-job	Poll a reload-safe AssetDatabase refresh through compilation or domain reload.
Safe assets	unity_asset_import	asset/import	Preflight and import external assets with shared TextureImporter defaults, decoded-pixel/file-byte deduplication, frame-batched execution, per-item results, and rollback.
Safe assets	unity_asset_import_unitypackage	asset/import-unitypackage	Start a reload-safe, non-interactive .unitypackage import; poll unity_jobs_get until callback-confirmed completion, with packaged .meta GUIDs preserved.
Safe assets	unity_asset_rename	asset/rename	Rename an asset through AssetDatabase.RenameAsset, preserving .meta, GUID, references, and Single Sprite internal names.
Safe assets	unity_asset_move	asset/move	Preflight and move one or more assets, preserving .meta GUIDs, synchronizing Single Sprite internal names when filenames change, and rolling back completed moves when configured to stop on failure.
Scene references	unity_component_set_reference	component/set-reference	Assign one or more ObjectReference properties with execution.mode and shared target defaults.
Serialization	unity_serialized_object_get	serialized-object/get	Read serialized properties from a scene object, component, or asset.
Serialization	unity_serialized_object_set	serialized-object/set	Set one serialized property on a scene object, component, or asset.
Console inspection	unity_console_query	console/query	Filter recent console entries by time, log type, message, source stack frame, full stack text, or only entries after the last Play transition.
Compilation inspection	unity_compilation_errors	compilation/errors	Return tracked Unity compilation errors and warnings, always including a separate deprecated-warning summary even when filtering for errors.
Animator editing	unity_animation_transition_info	animation/transition-info	Read full Animator transition details, including conditions, exit time, duration, offset, and interruption settings.
Animator editing	unity_animation_update_state	animation/update-state	Modify an existing Animator state, including motion, speed, tag, position, write defaults, and default state.
Animator editing	unity_animation_update_transition	animation/update-transition	Modify an existing transition and add, update, remove, or replace transition conditions.
Animator editing	unity_animation_connect_states	animation/connect-states	Create directed pairwise transitions between a list of Animator states.
UI Toolkit assets	unity_uitoolkit_asset_inspect	uitoolkit/asset-inspect	Inspect UXML/USS assets for VisualElement names, type matches, unconditional class defaults, contextual selectors, and pseudo-state rules.
UI Toolkit static audit	unity_uitoolkit_audit_uss_styles	uitoolkit/audit-uss-styles	Find selectors that serve one authored element without a reusable, pseudo-state, generated-child, or runtime-class contract, plus declarations that repeat the same winning value from the loaded PanelSettings theme or another loaded stylesheet.
UI Toolkit static audit	unity_uitoolkit_audit_uxml_layout	uitoolkit/audit-uxml-layout	Find authored tooltip attributes, unconsumed authored element names, fully fixed flex partitions that should leave one flexible remainder, fixed cross-axis content wrappers inside single-axis ScrollViews, layout-only manually centered containers, removable single-child centering wrappers, visually inert centered-label stretching or growth, repeated inline layout variants, and inline declarations already supplied by a loaded USS default, including implicit UI Toolkit classes.
UI Toolkit runtime	unity_uitoolkit_runtime_documents	uitoolkit/runtime-documents	List runtime UIDocuments and their root visual element metadata.
UI Toolkit runtime	unity_uitoolkit_runtime_tree	uitoolkit/runtime-tree	Read a UIDocument visual tree, including optional style and bounds data.
UI Toolkit runtime	unity_uitoolkit_runtime_query	uitoolkit/runtime-query	Query runtime VisualElements by tree path, VisualElementPath name list, name, class, type, or text.
UI Toolkit runtime	unity_uitoolkit_runtime_style	uitoolkit/runtime-style	Read inline style, resolved style, bounds, and background asset metadata for a runtime element.
UI Toolkit runtime	unity_uitoolkit_runtime_repaint	uitoolkit/runtime-repaint	Repaint a runtime UIDocument or one selected VisualElement.
UI Toolkit runtime	unity_uitoolkit_refresh	uitoolkit/refresh	Refresh UI Toolkit assets, repaint panels, and return after stable editor frames.
UI Toolkit runtime	unity_uitoolkit_assert_layout	uitoolkit/assert-layout	Assert runtime layout constraints such as no-gap/no-overlap edge touching, edge alignment, center alignment, containment, and expected size.
UI Toolkit visual QA	unity_uitoolkit_locate_element	uitoolkit/locate-element	Locate an Editor or runtime UI Toolkit element and return bounds, crop rect, and context for later screenshots or pixel checks.
UI Toolkit visual QA	unity_uitoolkit_capture_element	uitoolkit/capture-element	Capture a UI Toolkit element by locating it in an Editor window or runtime UIDocument and cropping its containing window screenshot.
UI Toolkit visual QA	unity_uitoolkit_compare_element	uitoolkit/compare-element	Capture a UI Toolkit element and compare the crop with a reference image, optionally writing a diff image.
UI Toolkit visual QA	unity_uitoolkit_generated_children	uitoolkit/generated-children	Inspect generated UI Toolkit children such as arrows, checkmarks, scrollers, TabView internals, and unnamed unity-* subparts.
UI Toolkit visual QA	unity_uitoolkit_resource_audit	uitoolkit/resource-audit	Audit target elements and descendants for resolved background assets, highlighted-state misuse, and missing or forbidden assets.
UI Builder	unity_uitoolkit_builder_preview	uitoolkit/builder-preview	Open a UXML asset, enable Match Game View when visible content overflows the canvas, wait for a stable preview, and optionally capture the UI Builder window.
Screenshot utilities	unity_screenshot_crop	screenshot/crop	Crop a screenshot or image file to a PNG for focused visual inspection.
Screenshot utilities	unity_screenshot_scene	screenshot/scene	Capture the Scene View once and return a file, base64 PNG, or both.
Graphics utilities	unity_graphics_asset_preview	graphics/asset-preview	Render Unity's preview for a prefab or other supported asset as a base64 PNG.
Graphics utilities	unity_graphics_image_alpha_bounds	graphics/image-alpha-bounds	Inspect a PNG or texture asset and return visible alpha pixel bounds plus transparent margins.
Graphics utilities	unity_graphics_rect_gap	graphics/rect-gap	Measure a gap or overlap between two rectangles along selected edges.
Graphics utilities	unity_graphics_annotate_rects	graphics/annotate-rects	Draw rectangle borders onto screenshots or images for visual verification reports.
Graphics utilities	unity_graphics_compare_images	graphics/compare-images	Compare two screenshots or crop regions, return difference bounds and samples, and optionally write a highlighted diff image.
Sprite pipeline	unity_sprite_sheet_info	sprite/sheet-info	Inspect a sliced sprite sheet and return texture and sprite metadata.
Sprite pipeline	unity_sprite_replace_and_slice	sprite/replace-and-slice	Replace a sprite sheet PNG and slice it into numbered sprites while preserving sprite IDs by name.
Sprite pipeline	unity_sprite_slice_sheet	sprite/slice-sheet	Slice an existing sprite sheet into numbered sprites.
Sprite pipeline	unity_sprite_update_animation_clip	sprite/update-animation-clip	Rebuild a SpriteRenderer sprite animation curve from a sheet's sprites.
Sprite pipeline	unity_sprite_replace_slice_update_clip	sprite/replace-slice-update-clip	Replace a sheet, slice it, and update an AnimationClip in one call.
Texture pipeline	unity_texture_apply_sprite_preset	texture/apply-sprite-preset	Apply high-level TextureImporter/Sprite settings, including pixel sprite preset, PPU, pivot, border, and reference settings.
Texture pipeline	unity_texture_info	texture/info	Inspect texture dimensions and TextureImporter settings, including sprite PPU, pivot, and border.
Texture pipeline	unity_texture_set_import	texture/set-import	Configure TextureImporter type and settings, including Sprite and NormalMap, then reimport once.
Texture pipeline	unity_texture_find_duplicates	texture/find-duplicates	Audit project image assets for identical decoded pixels or file bytes across one or more folders.
Texture pipeline	unity_texture_import_image	texture/import-image	Import an image from a URL or local file into Assets, dedupe by hash, and apply sprite import settings.
Texture pipeline	unity_texture_check_ui_import_settings	texture/check-ui-import-settings	Check UI pixel-art image import settings, including pixel sprite defaults plus optional expected dimensions, border, and max texture size.
Player Build	unity_build_start	build/start	Start a persistent Player Build job and optionally run the built player.
Player Build	unity_build_get_job	build/get-job	Poll the Player Build job for its final BuildReport and optional run result.
Package management	unity_packages_update_git	packages/update-git	Update a Git package through a deferred route; same-commit updates skip Unity Package Manager resolve by default.
Package management	unity_packages_add	packages/add	Add a registry, Git, local, or tarball package through Unity Package Manager.
Package management	unity_packages_remove	packages/remove	Remove an installed package without blocking the Editor main thread.
Package management	unity_packages_search	packages/search	Search the package registry with bounded pagination.
Asset workspace	unity_asset_create_folder	asset/create-folder	Ensure an Assets folder hierarchy, with dry-run support.
Asset workspace	unity_asset_copy	asset/copy	Copy one or more Unity assets with overwrite snapshots and rollback.
Asset workspace	unity_asset_dependencies	asset/dependencies	Read paginated incoming and outgoing asset references.
Asset workspace	unity_asset_transaction	asset/transaction	Apply folder, copy, move, delete, and serialized edits as a rollback-capable transaction.
UI Toolkit authoring	unity_uitoolkit_edit_uxml	uitoolkit/edit-uxml	Edit UXML elements, attributes, classes, hierarchy, and text structurally.
UI Toolkit authoring	unity_uitoolkit_edit_uss	uitoolkit/edit-uss	Upsert/remove USS selectors and declarations structurally.
UI Toolkit authoring	unity_uitoolkit_authoring_transaction	uitoolkit/authoring-transaction	Apply multi-file UXML/USS edits with rollback.
Jobs	unity_jobs_list	jobs/list	List paginated job history owned by the calling agent.
Jobs	unity_jobs_get	jobs/get	Read one owned historical job snapshot.
Project extensions	unity_project_tools_list	project-tools/list	List compact project-tool names, descriptions, and behavior flags without parameter schemas.
Project extensions	unity_project_tools_get	project-tools/get	Get the complete descriptor and input schema for one project tool.
Project extensions	unity_project_tools_execute	project-tools/execute	Execute a project tool by toolName after inspecting its schema.

Project Extensions

Project-specific batch tools can live in the Unity project instead of this package. Put an Editor script in the project and mark a static method with MCPProjectToolAttribute:

using System.Collections.Generic;
using UnityMCP.Editor;

public static class ProjectMcpTools
{
    [MCPProjectTool("battleidle/add-property",
        Description = "Create and register a BattleIdle property.",
        InputSchemaJson = "{\"type\":\"object\",\"properties\":{\"id\":{\"type\":\"string\"}},\"required\":[\"id\"]}",
        MutatesAssets = true,
        FirstClass = true)]
    public static object AddProperty(Dictionary<string, object> args)
    {
        // Project-specific AssetDatabase / prefab / settings edits go here.
        return new { success = true };
    }
}

Project tools may opt into first-class concrete exposure from the Editor bridge with FirstClass = true, using a fully described schema:

{
  "route": "project-tools/call/battleidle/add-property",
  "toolName": "unity_pt_battle_add_prop",
  "inputSchema": {
    "type": "object",
    "properties": {
      "id": {
        "type": "string",
        "description": "Property identifier to add."
      }
    },
    "required": ["id"]
  }
}

Declare the behavior explicitly: use exactly one of ReadOnly = true, MutatesAssets = true, or MutatesRuntime = true. A first-class project tool must declare one of these operation kinds, a non-empty tool description, descriptions for every input property, and items schemas for arrays. Incomplete metadata is demoted safely to the three-stage catalog and returned with an exposureWarning. Tools without FirstClass = true stay out of the Editor bridge's first-class surface and use the same three-stage discovery contract as the rest of the project catalog. The companion Node MCP server intentionally keeps all project-defined tools behind list/get/execute so switching between open Unity projects cannot leak one project's concrete tools into another project's session.

First list compact summaries:

{
  "offset": 0,
  "limit": 100
}

Then request the selected tool's full schema:

{
  "toolName": "battleidle/add-property"
}

Finally execute it:

{
  "toolName": "battleidle/add-property",
  "args": {
    "id": "gold_amount"
  }
}

project-tools/list never returns inputSchema; only project-tools/get returns the detailed descriptor. Concrete project-tools/call/... routes are reserved for tools that explicitly opt into first-class exposure; project-tools/get plus project-tools/execute is the canonical workflow for the remaining project catalog.

Notes

• Use the upstream README for the general feature list and MCP setup flow.
• _meta/tools defaults to compact first-class metadata, 50 tools per page, and no schemas. Use includeSchema=true, offset, limit, and optional category as needed.
• Configure namespaces used by every editor/execute-code call under Project Settings > Unity MCP > Execute Code. Keep one namespace per line; the usings request field remains available for one-off imports.
• Successful wire responses omit the redundant inner success=true. Project-tool success envelopes are unwrapped, exact collection counts and completed-pagination aliases are omitted, and false truncation flags are absent. A partial page keeps only its collection, total, and nextOffset.
• Wire-only Unity values use compact scalar forms such as position: "(1,2)", rect: "(1,2)-(4,5),size:(3,3)", bounds: "(0,0,0)-(2,4,6),size:(2,4,6)", color: "rgba(1,0.5,0,1)", and margin: "LTRB(1,2,3,4)". Equivalent dictionary shapes, execute-code values, complete reflected Rect aliases, and dimension pairs inside larger results are compacted centrally; internally queued command data remains structured.
• Normal command replies do not repeat instance identity. Use the instance routes when project/port details are needed; wrong-project errors still keep the actual path, name, and port.
• Error payloads keep success=false, error, errorCode, and retryable; an identical message alias is omitted.
• Compilation diagnostics return isCompiling, counts.errors, counts.warnings, entries, and the independently surfaced deprecatedWarnings. Totals appear only when an entry list was actually truncated.
• Queue tickets keep atomic status snapshots through Unity domain reloads. Queued work and interrupted reads resume with the same ticket; transport wait timeouts never overwrite the persisted business state. prefab-asset/add-component also persists its pre-refresh/mutation phase and reconciles the prefab before resuming. Other interrupted mutations return UncertainAfterReload and require target reconciliation before a new request. Stable idempotency keys prevent retry submissions from duplicating work.
• For multiple Unity projects open at once, select or resolve the target instance before mutation. The MCP server forwards its path/name automatically, and the Editor rejects unbound mutations with target_project_required or mismatches with wrong_unity_project.
• Project binding fields such as expectedProjectPath and expectedProjectName are transport metadata. The bridge validates them before dispatch and does not forward them into a project tool's strict business-argument schema.
• unity_wait_editor_idle waits for both consecutive idle editor frames and a continuous idle time window (stableMs, default 500) to avoid returning before a delayed compile or asset import starts. Its timeout measures active Editor time and pauses while the AppDomain is reloading.
• Planned domain reloads keep the instance registry entry with isReloading=true; a successful bridge restart replaces it with a ready entry, while a real server stop or Editor quit still unregisters immediately.
• mcp/health is intended for diagnosing editor slowdown caused by MCP usage. It does not stop the bridge; use mcp/set-autostart to prevent the bridge from coming back automatically after reload.
• texture/import-image is the preferred route for Figma/exported UI images: pass sourceUrl or sourcePath, targetPath or targetFolder + assetName, then use preset=pixel-sprite and border when needed.
• For UI visual QA, use uitoolkit/locate-element first to confirm the measured semantic target, then uitoolkit/capture-element or uitoolkit/compare-element for local crops. Use uitoolkit/generated-children when controls such as TabView, DropdownField, Scroller, or ToggleButtonGroup may be drawing default child indicators.
• The UI Toolkit static audits are explicit read-only tools in every project. Automatic import and filesystem-write warnings are opt-in through ProjectSettings/UnityMCPUIToolkitAudit.json, so installing the package does not impose an authoring policy on unrelated projects. The configuration accepts automaticAudit.ussSingleUseStyles, automaticAudit.uxmlLayoutContracts, the default-on rules.uxmlTooltipAttributes, the optional pixelGrid.enabled and positive pixelGrid.step, assetRoots, runtimeSourceRoots, and excludePaths. The tooltip rule is also available under Project Settings > Unity MCP > UI Toolkit Audit. Pixel-grid auditing is off unless a project enables it, and checks structural offsets, margin/gap spacing, and padding in both USS declarations and UXML inline styles. The UXML audit reports every authored tooltip attribute while that rule is enabled. The USS audit also reports advanced text generation without auto sizing, ineffective text alignment on shrink-wrapped Labels centered by a sole-child parent, and inheritable text styles unnecessarily owned by those child Labels. Reasoned local exceptions use /* uss-audit: allow-single-use <reason> */, /* uss-audit: allow-redundant-declaration <reason> */, /* uss-audit: allow-off-grid-pixels <reason> */, /* uss-audit: allow-text-style-contract <reason> */, <!-- uxml-layout-audit: allow-manual-center <reason> -->, <!-- uxml-layout-audit: allow-repeated-inline <reason> -->, <!-- uxml-layout-audit: allow-redundant-inline <reason> -->, <!-- uxml-layout-audit: allow-inert-text-stretch <reason> -->, <!-- uxml-layout-audit: allow-inert-text-grow <reason> -->, <!-- uxml-layout-audit: allow-single-child-centering-wrapper <reason> -->, <!-- uxml-layout-audit: allow-fixed-scroll-cross-axis-size <reason> -->, <!-- uxml-layout-audit: allow-unconsumed-element-name <reason> -->, <!-- uxml-layout-audit: allow-fixed-flex-partition <reason> -->, <!-- uxml-layout-audit: allow-off-grid-pixels <reason> -->, and <!-- uxml-layout-audit: allow-tooltip <reason> -->.
• Prefab asset mutation tools return a summary-only prefabFileDiff by default. Pass includePrefabFileDiff=false to suppress it or request prefabFileDiffMode=minimal/full when line details are required. Use unity_prefab_asset_transaction_edit for multi-step edits.
• Prefab saves retry transient Windows file locks, including Win32 error 1224. YAML normalization and diff capture are auxiliary; prefab-asset/set-property reports persistence only after Unity serialized readback confirms the requested value.
• uitoolkit/builder-preview opens and screenshots UI Builder. Its GPU-composited viewport is captured from the temporarily raised on-screen window because Win32 PrintWindow only returns the shell. Unity does not expose a stable public UI Builder zoom API, so the route records requested zoom values but does not use reflection to force the viewport zoom.
• Runtime uitoolkit/capture-element crops from the Game View render texture, keeping UI panel coordinates aligned with pixels and avoiding black GPU surfaces in Editor-window captures.
• build/start returns a job ID before BuildPipeline.BuildPlayer begins. Poll build/get-job; the terminal result contains the authoritative BuildReport, so do not force an AssetDatabase refresh after a successful build. Keep overwrite=true for repeat tests so output folders do not accumulate.
• asset/refresh likewise returns a job ID. Poll asset/get-refresh-job; if scripts trigger a domain reload, the persisted workflow resumes after the Editor becomes idle instead of losing the active MCP response.
• unity_packages_update_git defaults to skipIfResolved=true. When the requested ref is a commit hash already recorded in packages-lock.json, the tool returns skipped=true without asking Unity Package Manager to resolve again. Pass force=true to force a resolve.
• This fork intentionally keeps the package smaller by removing local documentation images.
• The package is still the Unity Editor side only. You need an MCP server/client setup to call the tools from an assistant.
• Package updates can take time if Unity needs to fetch from GitHub. Pinning commits keeps project state reproducible.

License

This fork follows the upstream license. See LICENSE.