Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/sveltejs/ai-tools/writing-opencode-pluginsnpx skills add sveltejs/ai-tools --skill writing-opencode-pluginsgit clone --depth 1 https://github.com/sveltejs/ai-toolsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00063 | $0.01309 |
| Opus 5 | $0.00032 | $0.00655 |
| Sonnet 5 | $0.00013 | $0.00262 |
| Haiku 4.5 | $0.00006 | $0.00131 |
Grade A, and why
writing-opencode-plugins scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing OpenCode Plugins
Use this skill to implement production-quality OpenCode plugins. Treat the repository's exported types and runtime as authoritative because plugin APIs are evolving and public docs may lag.
Start Here
- Decide which runtime owns the feature.
- Read the relevant public type before writing code.
- Find one focused in-repository example using the same API.
- Implement the smallest target-specific module.
- Test loading, behavior, failure, and cleanup in the owning package.
| Need | Plugin target | Import | Configuration |
|---|---|---|---|
| Hooks, tools, auth, providers, model parameters, shell environment | Server | @opencode-ai/plugin |
opencode.json or auto-discovered .opencode/plugins/*.{ts,js} |
| Commands, keybindings, routes, dialogs, slots, themes, notifications | TUI | @opencode-ai/plugin/tui |
Explicit tui.json plugin entry |
| Both | Two target-only entrypoints | Both imports in separate files | Package exports ./server and ./tui |
Never export server and tui from the same module. Do not use server event hooks as a substitute for interactive TUI APIs.
Verify The Current Contract
Read these files before implementing unfamiliar behavior:
packages/plugin/src/index.ts: authoritative server plugin and hook types.packages/plugin/src/tool.ts: custom tool schema, context, permission, metadata, attachments, and result types.packages/plugin/src/tui.ts: authoritative TUI API and module types.packages/opencode/specs/tui-plugins.md: TUI loading, packaging, lifecycle, and API semantics.packages/opencode/src/plugin/shared.ts: target validation, IDs, and entrypoint resolution.packages/opencode/src/plugin/loader.ts: install, compatibility, and import behavior.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 127 lines · 63 tokens per session scan A f9687fb8abc9
writing-opencode-plugins is a skill published in the GitHub repository sveltejs/ai-tools (314 stars, last pushed 3d ago), licensed MIT. It adds 63 tokens to every session and 1,309 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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