docs: add OpenCode plugin and integration instructions

- Add beans-prime.ts plugin for OpenCode integration
- Document plugin location options (project-local vs user-global)
- Update README with OpenCode setup instructions

Author: hmans

.opencode/plugin/beans-prime.ts

@@ -0,0 +1,36 @@
+import type { Plugin } from "@opencode-ai/plugin";
+
+/**
+ * Beans Prime Plugin for OpenCode
+ *
+ * This plugin injects the output of `beans prime` into OpenCode's system prompt,
+ * giving the AI context about your project's beans (issues/tasks). It runs on:
+ *
+ * - Chat session start: Adds bean context to the system prompt
+ * - Session compaction: Re-injects context when the session is compacted
+ *
+ * Plugin Location Options:
+ *
+ * 1. Project-local (current): .opencode/plugin/beans-prime.ts
+ *    - Only available in this project
+ *    - Committed to version control, shared with collaborators
+ *
+ * 2. User-global: ~/.opencode/plugin/beans-prime.ts
+ *    - Available in all your projects that use beans
+ *    - Personal configuration, not shared
+ */
+
+export const BeansPrimePlugin: Plugin = async ({ $ }) => {
+  const primeOuput = await $`beans prime`.text();
+
+  return {
+    "experimental.chat.system.transform": async (_, output) => {
+      output.system.push(primeOuput);
+    },
+    "experimental.session.compacting": async (_, output) => {
+      output.context.push(primeOuput);
+    },
+  };
+};
+
+export default BeansPrimePlugin;

README.md

@@ -75,7 +75,7 @@ But more importantly, you'll want to get your coding agent set up to use it. Let
 
 We'll need to teach your coding agent that it should use Beans to track tasks, and how to do so. The exact steps will depend on which agent you're using.
 
-### Claude Code
+### [Claude Code](https://www.claude.com/product/claude-code)
 
 An official Beans plugin for Claude is in the works, but for the time being, please manually add the following hooks to your project's `.claude/settings.json` file:
 
@@ -92,6 +92,10 @@ An official Beans plugin for Claude is in the works, but for the time being, ple
 }
 ```
 
+### [OpenCode](https://opencode.ai/)
+
+Beans integrates with OpenCode via a plugin that injects task context into your sessions. To set it up, **copy the plugin** from [`.opencode/plugin/beans-prime.ts`](.opencode/plugin/beans-prime.ts) to your project's `.opencode/plugin/` directory (or `~/.opencode/plugin/` for global availability across all projects).
+
 ### Other Agents
 
 You can use Beans with other coding agents by configuring them to run `beans prime` to get the prompt instructions for task management. We'll add specific integrations for popular agents over time.