feat: add openclaw-plugin-dev skill

Plugin development reference and workflows based on real development
experience (Dirigent, ContractorAgent, PrismFacet).

Docs: structure, entry-point, hooks, tools, state, config, debugging
Workflows: create-plugin, add-hook

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openclaw-plugin-dev/workflows/add-hook.md

@@ -0,0 +1,40 @@
+# Add Hook
+
+When adding a new hook handler to an existing plugin.
+
+> See `{baseDir}/docs/hooks.md` for available hooks and dedup patterns.
+
+## Process
+
+### 1. Create Hook File
+
+Add `plugin/hooks/<hook-name>.ts`. Export a registration function:
+
+```typescript
+export function registerMyHook(api, config) {
+  // Set up dedup on globalThis
+  // api.on("<hook-name>", handler)
+}
+```
+
+### 2. Add Dedup
+
+Choose the right dedup pattern:
+- `before_model_resolve`, `before_prompt_build` → WeakSet on event object
+- `agent_end` → Set on runId with size cap (500)
+- `gateway_start/stop` → globalThis flag (in index.ts, not in hook file)
+
+### 3. Register in index.ts
+
+Import and call the registration function in the `register()` method.
+
+Hooks that need to run every register() call (agent-scoped): put outside the lifecycle guard.
+Hooks that should run once (gateway-scoped): put inside the lifecycle guard.
+
+### 4. If Prompt Injection
+
+If the hook returns `prependSystemContext` or `appendSystemContext`, ensure `allowPromptInjection: true` is set in the plugin's config entry and in the install script.
+
+### 5. Test
+
+Reinstall, restart gateway, verify via logs.