mcpbeat

Test Level

facebook/test-level

Test level system (LevelRoot, LevelTag, authored environment, scene hierarchy) against the poke example using the iwsdk CLI.

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on the repository, not the skill itself

Install

one command, takes just this skill from the repository
npx skills add https://github.com/facebook/immersive-web-sdk --skill test-level

What it tells the agent to use

found in the instruction text
Bash runs shell commands — read the instruction before connecting

The instruction itself

18 sections, as written by the author

Level System Test

Run 5 test suites covering LevelRoot, LevelTag membership, authored environment, scene hierarchy, and stability.

Configuration:

  • EXAMPLE_DIR: $IWSDK_REPO_ROOT/examples/poke

Tool calls: every tool call is npx iwsdk <subcommand> [--input-json '<JSON>'] [--timeout <ms>], run from inside the example workspace (cwd $EXAMPLE_DIR). The CLI auto-discovers the IWSDK app root from cwd, so no path tricks are required. Run npx iwsdk mcp inspect from the example to discover available tools and their CLI subcommands.

  • <JSON> is a JSON object string. Omit --input-json if no arguments are needed.
  • Output is JSON on stdout: {ok, workspaceRoot, operation, result}. Parse it to check assertions.
  • Use --timeout 20000 for operations that may take longer (reload, xr enter, screenshot).

IMPORTANT: Run each Bash command one at a time. Parse the JSON output and verify assertions before moving to the next command. Do NOT chain multiple CLI commands together.

IMPORTANT: When the instructions say "wait N seconds", use sleep N as a separate Bash command.


Step 1: Install Dependencies

cd $IWSDK_REPO_ROOT/examples/poke && npm run fresh:install

Wait for this to complete before proceeding.


Step 2: Start Dev Server

Start the dev server as a background task using the Bash tool's run_in_background: true parameter:

cd $IWSDK_REPO_ROOT/examples/poke && npm run dev

IMPORTANT: This command MUST be run with run_in_background: true on the Bash tool — do NOT append & to the command itself.

Once the background task is launched, poll the output for Vite's ready message (up to 60s). You can also run npx iwsdk dev status from the example directory until state.running becomes true. You do not need to extract or manage the port yourself; subsequent commands resolve the active runtime through the CLI automatically.

If the server fails to start within 60 seconds, report FAIL for all suites and skip to Step 5.


Step 3: Verify Connectivity

npx iwsdk ecs systems 2>/dev/null

This must return JSON with a list of systems. If it fails:

  • Check the dev server output for errors
  • Try killing and restarting the server (Step 2)
  • If it still fails, report FAIL for all suites and skip to Step 5

Step 4: Run Test Suites

Pre-test Setup

Run these commands in order:

  • npx iwsdk browser reload --timeout 20000 2>/dev/null

Then: sleep 3

  • npx iwsdk xr enter --timeout 20000 2>/dev/null

Then: sleep 2

  • npx iwsdk browser logs --input-json '{"count":20,"level":["error","warn"]}' 2>/dev/null

Assert: No error-level logs.


Suite 1: LevelRoot

Test 1.1: Find LevelRoot Entity

npx iwsdk ecs find --input-json '{"withComponents":["LevelRoot"]}' 2>/dev/null

Assert: Exactly 1 entity. Save its entityIndex as <root>.

Entity should have name "LevelRoot".

Entity should also have: Transform, LevelTag, DomeGradient, IBLGradient.

Test 1.2: LevelRoot Transform at Identity

npx iwsdk ecs query --input-json '{"entityIndex":<root>,"components":["Transform"]}' 2>/dev/null

Assert:

  • position: [0, 0, 0] (approximately)
  • orientation: [0, 0, 0, 1]
  • scale: [1, 1, 1]

The LevelSystem enforces identity transform on the level root every frame.


Suite 2: LevelTag Membership

Test 2.1: All Level Entities Tagged

npx iwsdk ecs find --input-json '{"withComponents":["LevelTag"]}' 2>/dev/null

Assert: Multiple entities — all entities except entity 0 (scene root, which is persistent).

Test 2.2: LevelTag ID Matches

Pick any tagged entity from the results above:

npx iwsdk ecs query --input-json '{"entityIndex":<any-tagged>,"components":["LevelTag"]}' 2>/dev/null

Assert: id = "level:default"

All tagged entities should have the same id value ("level:default" for the initial level).

Test 2.3: Persistent Entities Excluded

npx iwsdk ecs find --input-json '{"withComponents":["Transform"],"withoutComponents":["LevelTag"]}' 2>/dev/null

Assert: 10 entities — entity 0 (scene root) plus 9 persistent input-rig entities created by the world bootstrap (xrOrigin, head, ray/grip/indexTip spaces for left and right). None of these should carry LevelTag.


Suite 3: Authored Environment

Test 3.1: LevelRoot Has Both Environment Components

npx iwsdk ecs query --input-json '{"entityIndex":<root>,"components":["DomeGradient","IBLGradient"]}' 2>/dev/null

Assert: Both scene-authored components are present with the gradient values

declared in public/scenes/poke.iwsdk.scene.json. They are not synthesized by

LevelSystem.


Suite 4: Scene Hierarchy

Test 4.1: LevelRoot is Child of Scene Root

npx iwsdk scene runtime-hierarchy --input-json '{"maxDepth":2}' 2>/dev/null

Assert:

  • Scene root children include "LevelRoot"
  • LevelRoot children include all level entities (env mesh, robot, panel, logo, etc.)

Test 4.2: Entity Count

npx iwsdk ecs find --input-json '{"limit":50}' 2>/dev/null

Assert: Total entity count should be >= 5.


Suite 5: Stability

npx iwsdk browser logs --input-json '{"count":30,"level":["error","warn"]}' 2>/dev/null

Assert: No application-level errors or warnings. Pre-existing 404 resource errors from page load are acceptable.


Step 5: Cleanup & Results

Kill the dev server:

cd $IWSDK_REPO_ROOT/examples/poke && npx iwsdk dev down

Output a summary table:

| Suite                  | Result    |
|------------------------|-----------|
| 1. LevelRoot           | PASS/FAIL |
| 2. LevelTag Membership | PASS/FAIL |
| 3. Authored Environment | PASS/FAIL |
| 4. Scene Hierarchy     | PASS/FAIL |
| 5. Stability           | PASS/FAIL |

If any suite fails, include which assertion failed and actual vs expected values.


Recovery

If at any point a transient error occurs (server crash, WebSocket timeout, connection refused, etc.) that is NOT caused by a source code bug:

  • Stop the dev server: cd $IWSDK_REPO_ROOT/examples/poke && npx iwsdk dev down
  • Restart: re-run Step 2 to start a fresh dev server
  • Re-run the Pre-test Setup (reload, accept session)
  • Retry the failed suite

Only give up after one retry attempt per suite. If the same suite fails twice, mark it FAIL and continue to the next suite.


Known Issues & Workarounds

LevelTag id for default level

When no GLXF level URL is provided, the level id is "level:default". All entities created via world.createTransformEntity() (without persistent: true) automatically receive LevelTag with this id.

Level root identity enforcement

LevelSystem.update() checks and resets the level root's transform to identity every frame. If you modify the level root's position via ecs set-component, it will be reset on the next frame.

Entity 0 is special

Entity 0 wraps the Three.js Scene object. It has Transform but no LevelTag — it's the persistent root that survives level changes.

Entity indices change on reload

Never cache entity indices across page reloads. Always re-discover via npx iwsdk ecs find.

How to use it

Copy the folder

Take facebook/test-level from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.

Install what it needs

The instructions reference npx. Without those the skill loads but fails at the first command.