feat: add opencode plugin for Mnemosyne routing

TypeScript plugin that injects baseURL to route Anthropic API calls through the Mnemosyne gateway, enriches compaction with memory context, and provides mnemosyne_status/mnemosyne_query custom tools. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
2026-03-13 11:41:36 -06:00 · 2026-03-13 11:41:36 -06:00 · b21871b8fc
commit b21871b8fc
parent 9b25b33a50
4 changed files with 629 additions and 0 deletions
--- a/opencode-plugin/INSTALL.md
+++ b/opencode-plugin/INSTALL.md
@ -0,0 +1,99 @@
+# Installing opencode-mnemosyne
+
+## Prerequisites
+
+1. **Mnemosyne gateway** running (`mnemosyne --no-launch --port 8080`)
+2. **opencode** installed and configured
+3. **OAuth authenticated** (`mnemosyne --login`)
+
+## Quick Install (Local Development)
+
+```bash
+# From the contextmanager project root
+cd opencode-plugin
+npm install && npm run build
+
+# Register as a local plugin in opencode
+# Add to your ~/.config/opencode/opencode.json:
+```
+
+```json
+{
+  "plugin": [
+    "oh-my-opencode@latest",
+    "file:///var/home/joey/Projects/contextmanager/opencode-plugin"
+  ]
+}
+```
+
+## Configuration
+
+The plugin is configured via environment variables:
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `MNEMOSYNE_HOST` | `127.0.0.1` | Gateway host |
+| `MNEMOSYNE_PORT` | `8080` | Gateway port |
+| `MNEMOSYNE_LOG_LEVEL` | `info` | Log level: silent, error, info, debug |
+
+## Usage
+
+### 1. Start the Mnemosyne Gateway
+
+```bash
+cd ~/Projects/contextmanager
+mnemosyne --no-launch --port 8080
+```
+
+### 2. Start opencode normally
+
+The plugin automatically:
+- Routes Anthropic API calls through the gateway (via `baseURL` injection)
+- Enriches compaction prompts with memory context
+- Provides `mnemosyne_status` and `mnemosyne_query` tools
+
+### 3. Custom Tools
+
+Once loaded, the LLM has access to two new tools:
+
+- **`mnemosyne_status`** — Show memory state (objects, tokens, evictions, faults)
+- **`mnemosyne_query`** — Query the backing store for previously evicted context
+
+### How It Works
+
+```
+opencode → plugin (config hook injects baseURL) → Mnemosyne gateway → Anthropic API
+                                                        ↕
+                                              Object Store (backing store)
+                                              Helper LLM (Haiku 4.5)
+                                              Fidelity Manager
+                                              Segmenter + Embedder
+```
+
+The plugin's `config` hook dynamically sets `provider.anthropic.options.baseURL` to
+the gateway URL. This means all Anthropic API calls are transparently proxied through
+Mnemosyne, which:
+
+1. **Segments** conversation into semantic objects
+2. **Stores** objects with embeddings in the backing store
+3. **Compresses** old objects via multi-fidelity degradation (L0→L1→L2→L3→L4)
+4. **Retrieves** evicted content on demand via micro-faults
+5. **Detects** topic shifts and reclassifies goals
+
+### Graceful Degradation
+
+If the gateway is not running, the plugin silently skips all hooks. opencode works
+normally with no proxy — zero impact on the user experience.
+
+## npm Install (once published)
+
+```bash
+# In your opencode.json
+{
+  "plugin": [
+    "opencode-mnemosyne@latest"
+  ]
+}
+```
+
+Then set `MNEMOSYNE_PORT=8080` in your environment.