feat: add compaction prompt plugin

2026-08-18 13:42:55 +00:00 · 2026-08-01 16:51:37 +05:30
commit 9b70b18295
13 changed files with 543 additions and 0 deletions
@@ -0,0 +1,56 @@
+# opencode-plugin-compaction-prompt
+
+Customize OpenCode's compaction prompt to guide which context carries forward, which details are omitted, and what the next session should retain.
+
+## Install
+
+```bash
+opencode plugin opencode-plugin-compaction-prompt
+```
+
+Or add it to `opencode.json` manually:
+
+```json
+{
+  "$schema": "https://opencode.ai/config.json",
+  "plugin": [
+    [
+      "opencode-plugin-compaction-prompt",
+      {
+        "memoryFile": ".opencode/compaction.md",
+        "mode": "append",
+        "completionMarker": "Custom compaction request honored."
+      }
+    ]
+  ]
+}
+```
+
+Create `.opencode/compaction.md` in the project when you have project-specific context to preserve. The file is optional.
+
+## Options
+
+| Option             | Default                              | Description                                                                                                |
+| ------------------ | ------------------------------------ | ---------------------------------------------------------------------------------------------------------- |
+| `memoryFile`       | `.opencode/compaction.md`            | File resolved relative to the active worktree.                                                             |
+| `mode`             | `append`                             | Append instructions to OpenCode's default prompt, or use `replace` to provide a complete prompt.           |
+| `prompt`           | Built-in preservation prompt         | Additional instructions used together with `memoryFile`; both are included in the compaction instructions. |
+| `completionMarker` | `Custom compaction request honored.` | Exact text the model is asked to append at the end of the summary.                                         |
+
+Append mode is the recommended default because it preserves OpenCode's built-in compaction behavior. Replace mode is available when the complete prompt needs to be controlled by this plugin.
+
+## Development
+
+```bash
+bun install
+bun test
+bun run typecheck
+bun run build
+bun run pack:check
+```
+
+The npm package exposes the compiled entrypoint at `dist/index.js` and TypeScript declarations at `dist/index.d.ts`.
+
+## Compatibility
+
+The plugin uses OpenCode's `experimental.session.compacting` hook. OpenCode may change experimental plugin APIs between releases; test the package against the OpenCode version you support.