Initial scaffold: open-memory plugin for OpenCode

- Plugin entry point with hooks: experimental.session.compacting,
  experimental.chat.system.transform, event
- Context tracker: SSE-based token tracking per session with
  green/yellow/red/critical thresholds
- Tools: memory_context, memory_compact, memory_summary,
  memory_sessions, memory_messages, memory_search, memory_plans
- History module: sqlite3 queries + markdown rendering
- Compaction: improved prompt emphasizing self-continuity
- Research docs: ARCHITECTURE.md + opencode-memory reference

src/index.ts

@@ -0,0 +1,57 @@
+import type { Plugin, PluginInput } from "@opencode-ai/plugin";
+import { createTools } from "./tools.js";
+import { startContextTracker } from "./context/tracker.js";
+import { getCompactionPrompt } from "./compaction/prompt.js";
+
+const OpenMemoryPlugin: Plugin = async (ctx) => {
+  const contextTracker = startContextTracker(ctx);
+
+  return {
+    tool: createTools(ctx, contextTracker),
+
+    "experimental.session.compacting": async (_input, output) => {
+      output.prompt = getCompactionPrompt();
+    },
+
+    "experimental.chat.system.transform": async (input, output) => {
+      if (!input.sessionID) return;
+
+      const info = contextTracker.getContextInfo(input.sessionID);
+      if (!info) return;
+
+      const statusEmoji =
+        info.status === "critical"
+          ? "🔴"
+          : info.status === "red"
+            ? "🟠"
+            : info.status === "yellow"
+              ? "🟡"
+              : "🟢";
+
+      const advisory =
+        info.status === "critical"
+          ? "Context is nearly full. Use memory_compact immediately if possible."
+          : info.status === "red"
+            ? "Context is running low. Use memory_compact at your next natural break point."
+            : info.status === "yellow"
+              ? "Context usage is getting high. Consider memory_compact when convenient."
+              : null;
+
+      const lines = [
+        `${statusEmoji} Context: ${info.percentage}% used (${info.usedTokens.toLocaleString()} / ${info.limitTokens.toLocaleString()} tokens, ${info.model})`,
+      ];
+
+      if (advisory) {
+        lines.push(advisory);
+      }
+
+      output.system.push(lines.join("\n"));
+    },
+
+    event: async ({ event }) => {
+      contextTracker.handleEvent(event);
+    },
+  };
+};
+
+export default OpenMemoryPlugin;