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Create Gsd Extension · open-gsd | DecimalAI

agent toolingby open-gsd

Create Gsd Extension

open-gsd/create-gsd-extension

Source open-gsd/gsd-pi ↗License MIT

Create, debug, and iterate on GSD extensions (TypeScript modules adding tools, commands, event hooks, custom UI, and providers).

SkillScore91Maintained

Automatic

AI Engineer pack

Last verified 9/29/2026

What it changes

Passed 20 of 22 test cases with the skill, and 8 of 22 without it.

Without skill36%

With skill91%

Checks it passed that the model alone missed

The event listener registers via pi.on().
The shell execution uses the pi.exec method.
The parameter schema uses StringEnum from @gsd/pi-ai.

and 21 more in the full report

14 fixed6 passed either way0 still failing2 broke

Pass-rate lift: +55 pp
Tokens: +21%
Agent turns: 0%
Response time: -40%

Model gemini-3.6-flashMeasured 9/29/2026v1 · latest is v220 of 22 cases passed with skill

Tokens, turns and time describe resource use, not a dollar price.

This benchmark measured an earlier version of the skill.

A newer attempt on gemini-3.6-flash on 10/11/2026 did not produce a publishable comparison (not comparable). The snapshot above is the previously measured run.

Use this skill

Save it into your project's skills folder. Claude Code picks it up in its next session.

curl -fsSL --create-dirs -o .claude/skills/open-gsd-create-gsd-extension/SKILL.md https://app.decimal.ai/s/open-gsd-create-gsd-extension/SKILL.md

Want it pinned and updatable? pip install "decimalai>=0.15", then decimalai skills add open-gsd-create-gsd-extension, and start Claude Code with claude --plugin-dir "$(git rev-parse --show-toplevel)/.agents"

1 · One-time — install the CLI (docs ↗)

pip install "decimalai>=0.15"

2 · Get the skill — writes .agents/skills/open-gsd-create-gsd-extension/ and pins it in .decimal/skills.lock

decimalai skills add open-gsd-create-gsd-extension

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/open-gsd-create-gsd-extension/SKILL.md https://app.decimal.ai/s/open-gsd-create-gsd-extension/SKILL.md

Raw file: /s/open-gsd-create-gsd-extension/SKILL.md ↗ · machine-readable summary at /s/open-gsd-create-gsd-extension.json ↗

Safety checks: 3 of 3 passed

Code scan CleanIntent PassedContent Clean

See it in action

One of 14 test cases the skill fixed. Same model, same prompt, with and without the skill.

1 of 14

Prompt

I am creating a distributable GSD extension module. Besides the main TypeScript entry file, what manifest file is required, and what key field must list all capabilities provided by the extension?

What was checked, without and with the skill
Checked	Without skill	With skill
The extension configuration uses extension-manifest.json.	Missed	Passed
The manifest file includes a provides field listing extension capabilities.	Missed	Passed

case-14 · gemini-3.6-flash · 9/29/2026 · answers are capped and redacted

What's inside

The instructions your model reads when the skill loads.

SKILL.md95 lines20 files

<essential_principles>

Extensions are TypeScript modules that hook into GSD's runtime (built on pi). They export a default function receiving ExtensionAPI and use it to subscribe to events, register tools/commands/shortcuts, and interact with the session.

GSD extension paths (community/user-installed extensions):

Global: ~/.pi/agent/extensions/*.ts or ~/.pi/agent/extensions/*/index.ts
Project-local: .gsd/extensions/*.ts or .gsd/extensions/*/index.ts

Note: ~/.gsd/agent/extensions/ is reserved for bundled extensions synced from the gsd-pi package. Community extensions placed there are silently ignored by the loader.

The three primitives:

Events — Listen and react (pi.on("event", handler)). Can block tool calls, modify messages, inject context.
Tools — Give the LLM new abilities (pi.registerTool()). LLM calls them autonomously.
Commands — Give users slash commands (pi.registerCommand()). Users type /mycommand.

Non-negotiable rules:

Use StringEnum from @gsd/pi-ai for string enum params (NOT Type.Union/Type.Literal — breaks Google's API)
Truncate tool output to 50KB / 2000 lines max (use truncateHead/truncateTail from @gsd/pi-coding-agent)
Store stateful tool state in details for branching support
Check signal?.aborted in long-running tool executions
Use pi.exec() not child_process for shell commands
Check ctx.hasUI before dialog methods (non-interactive modes exist)
Session control methods (waitForIdle, newSession, fork, navigateTree, reload) are ONLY available in command handlers — they deadlock in event handlers
Lines from render() must not exceed width — use truncateToWidth()
Use theme from callback params, never import directly
Strip leading @ from path params in custom tools (some models add it)

Available imports:

Package	Purpose
`@gsd/pi-coding-agent`	`ExtensionAPI`, `ExtensionContext`, `Theme`, event types, tool utilities, `DynamicBorder`, `BorderedLoader`, `CustomEditor`, `highlightCode`
`@sinclair/typebox`	`Type.Object`, `Type.String`, `Type.Number`, `Type.Optional`, `Type.Boolean`, `Type.Array`
`@gsd/pi-ai`	`StringEnum` (required for string enums), `Type` re-export
`@gsd/pi-tui`	`Text`, `Box`, `Container`, `Spacer`, `Markdown`, `SelectList`, `Input`, `matchesKey`, `Key`, `truncateToWidth`, `visibleWidth`
Node.js built-ins	`node:fs`, `node:path`, `node:child_process`, etc.

Track record

Benchmark

20 / 22

test cases passed, vs 8 / 22 without

Adoption

Users: 0
Times used: 0

Safety and source details

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v5 — 10/8/2026

View 15 scanner checks

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

open-gsd / gsd-pi

src/resources/skills/create-gsd-extension/SKILL.md

View on GitHub ↗

License MITImported 10/8/2026Version v2Bundled 19 files

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