メニュー
Spawn an autonomous sub-agent that implements a test Scratch program using only a newly written skill, then reports whether the skill's documentation is accurate, complete, and sufficient to produce working code.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
| name | scratch-skill-tester |
| description | Spawn an autonomous sub-agent that implements a test Scratch program using only a newly written skill, then reports whether the skill's documentation is accurate, complete, and sufficient to produce working code. |
This skill validates a newly created SKILL.md by having a fresh, isolated agent attempt to build a Scratch program using only that skill. Because the agent starts without any memory of the original coding session, it will expose missing documentation, wrong code examples, and hidden assumptions.
Run this skill immediately after scratch-skill-creator produces a new SKILL.md. Also run it after editing a SKILL.md in response to prior test failures.
Before invoking, confirm you have:
skills/scratch-clone-pen-trail/SKILL.mdSpawn a sub-agent using the tool available in your environment:
runSubagent toolTask tool with subagent_type: "general-purpose"Construct the prompt as follows:
You are a Scratch programming agent. Your job is to build a working Scratch program
using ONLY the instructions in the skill file provided below. Do not rely on any
knowledge beyond what the skill file contains plus the general scratch-project-edit
and scratch-operation skills you already know.
## Skill to Test
<paste the full contents of the new SKILL.md here>
## Program to Build
<describe the test program here — be concrete about what should appear on screen
and what the user should observe when they click the green flag>
## Save Path
./tmp/<skill-name>/test.sb3
## Your Task
1. Open the Scratch editor at https://scratch.mit.edu/projects/editor/
2. Connect to the VM using the standard approach
3. Implement the program using ONLY the pattern described in the skill above
4. Run the program and take a screenshot; save the screenshot to `./tmp/<skill-name>/screenshot-build.png`
5. Run `mkdir -p ./tmp/<skill-name>` to create the directory, then save the project as an .sb3 file to the save path above using the scratch-project-file download pattern
6. **Reload test**: Load the saved `.sb3` file back into the Scratch editor using the scratch-project-file load pattern, then click the green flag and confirm the program runs correctly. Take a screenshot and save it to `./tmp/<skill-name>/screenshot-reload.png`
7. Report the result in this format:
### Test Report
**Status**: PASS / PARTIAL / FAIL
**Build screenshot**: [attached or described]
**Reload screenshot**: [attached or described — confirms the saved .sb3 runs correctly after loading]
**Saved project**: <path to saved .sb3 file, or "not saved" with reason>
**Reload test**: PASS / FAIL — <brief description of what happened when the project was loaded and re-run>
**What worked**: <list>
**What failed or was unclear**: <list — be specific about which section of the
SKILL.md was missing, wrong, or ambiguous>
**Suggested SKILL.md fixes**: <concrete edits — quote the problematic line and
propose a replacement>
The ./tmp folder is used exclusively for temporary test artifacts produced by the sub-agent — Scratch project files (.sb3) and screenshots taken during a test run. It is not used for skill files.
| Artifact | Location |
|---|---|
Sub-agent test project (.sb3) | ./tmp/<skill-name>/test.sb3 |
| Sub-agent build screenshot | ./tmp/<skill-name>/screenshot-build.png |
| Sub-agent reload screenshot | ./tmp/<skill-name>/screenshot-reload.png |
| New skill file | skills/<skill-name>/SKILL.md |
| Creator example project | skills/<skill-name>/example.sb3 |
Before saving, create the tmp directory:
mkdir -p ./tmp/<skill-name>
If multiple test rounds are needed, use numbered filenames: ./tmp/<skill-name>/test-1.sb3, ./tmp/<skill-name>/test-2.sb3, etc.
Note:
./tmpis gitignored and must never be committed. Skill files underskills/are what get committed.
The agent successfully built and ran the program. The SKILL.md is ready.
Next steps:
.sb3 was saved to ./tmp/<skill-name>/test.sb3.skills/<skill-name>/SKILL.md.skills/ (SKILL.md, example.sb3). Do not commit anything under ./tmp.The agent built something but it didn't fully work, or the agent had to guess at undocumented details.
Next steps:
The agent could not build the program at all, or produced something completely wrong.
Common causes:
Next steps:
[scratch-skill-tester] → FAIL/PARTIAL
│
▼
Read agent's "Suggested SKILL.md fixes"
│
▼
Edit SKILL.md (add examples, fix opcodes, clarify tips)
│
▼
[scratch-skill-tester] again (same test program)
│
▼ (repeat until PASS)
After two consecutive PASS results with different test programs, the skill is considered stable.
You are a Scratch programming agent. Build a working Scratch program using ONLY the
instructions in the skill file below.
## Skill to Test
---
name: scratch-clone-pen-trail
description: Pattern for creating multiple clones that each draw colored pen trails
while bouncing off edges, using correct clone initialization order.
---
# Scratch Clone Pen Trail
... (full SKILL.md contents) ...
## Program to Build
Create a Scratch program where 8 clones of a small circle sprite each start at a
random position on the stage, move in random directions, and draw a pen trail in
their own unique color. When a clone hits an edge it should bounce. The result
should look like 8 colored squiggly lines drawn simultaneously over about 5 seconds.
## Save Path
./tmp/scratch-clone-pen-trail/test.sb3
## Your Task
1. Open https://scratch.mit.edu/projects/editor/
2. Connect to VM
3. Implement using the clone-pen-trail pattern
4. Click green flag, wait 5 seconds
5. Run `mkdir -p ./tmp/scratch-clone-pen-trail`, take a screenshot and save it to `./tmp/scratch-clone-pen-trail/screenshot-build.png`
6. Save the project as .sb3 to the save path above
7. Load the saved .sb3 back into the editor, click green flag again, take a screenshot and save it to `./tmp/scratch-clone-pen-trail/screenshot-reload.png`
8. Report: PASS / PARTIAL / FAIL with details including the reload test result
If the test program is identical to the skill creator's example, the agent may reproduce it from general knowledge rather than truly relying on the SKILL.md. Use the same technique but a different theme.
Focus the test program on the most complex or unusual aspect of the skill — the part most likely to be underdocumented.
Do not reuse a test agent across multiple test rounds. Each round should use a fresh agent invocation so it has no memory of previous attempts.
After the agent reports PASS, check both screenshots:
screenshot-build.png — confirms the program worked immediately after codingscreenshot-reload.png — confirms the saved .sb3 is a complete, self-contained project that runs correctly after loadingAgents sometimes report success optimistically. If the reload screenshot looks different from the build screenshot (e.g. blank stage, missing sprites), the save/load cycle has a bug and the test should be marked PARTIAL or FAIL. ,
Build a Scratch program from a user prompt using vibe coding, then distill the novel techniques into a new reusable SKILL.md. Use this skill when you want to grow the skills collection with a new pattern discovered during live coding.
Pattern for coordinating pen drawing across multiple sprites. Uses a stage-based broadcast to ensure "pen clear" runs once before all sprites begin drawing, preventing partial erasure.
Pattern for storytelling with sequential dialog (message chaining) and simultaneous speech (parallel broadcast). Combines backdrop switching with broadcast messages to create multi-scene conversations between characters.