diff --git a/src/config.ts b/src/config.ts
index 0aca56b..d467991 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -26,6 +26,7 @@ interface SupermemoryConfig {
 }
 
 const DEFAULT_KEYWORD_PATTERNS = [
+  // English
   "remember",
   "memorize",
   "save\\s+this",
@@ -42,6 +43,18 @@ const DEFAULT_KEYWORD_PATTERNS = [
   "remember\\s+that",
   "never\\s+forget",
   "always\\s+remember",
+  // Japanese
+  "覚えて",
+  "記憶して",
+  "メモして",
+  "保存して",
+  "忘れないで",
+  "忘れるな",
+  "記録して",
+  "覚えておいて",
+  "メモっておいて",
+  "メモっといて",
+  "ノートして",
 ];
 
 const DEFAULTS: Required<Omit<SupermemoryConfig, "apiKey" | "userContainerTag" | "projectContainerTag">> = {
diff --git a/src/index.ts b/src/index.ts
index 7a5a441..a514a69 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -7,6 +7,7 @@ import { formatContextForPrompt } from "./services/context.js";
 import { getTags } from "./services/tags.js";
 import { stripPrivateContent, isFullyPrivate } from "./services/privacy.js";
 import { createCompactionHook, type CompactionContext } from "./services/compaction.js";
+import { generatePartId } from "./services/ids.js";
 
 import { isConfigured, CONFIG } from "./config.js";
 import { log } from "./services/logger.js";
@@ -80,6 +81,51 @@ export const SupermemoryPlugin: Plugin = async (ctx: PluginInput) => {
       })
     : null;
 
+  // Track messages per session for auto-save on session end
+  const sessionMessages = new Map<string, string[]>();
+
+  const collectMessage = (sessionID: string, text: string) => {
+    if (!text.trim()) return;
+    const messages = sessionMessages.get(sessionID) || [];
+    // Keep last N messages to avoid unbounded growth
+    const MAX_TRACKED = 50;
+    if (messages.length >= MAX_TRACKED) messages.shift();
+    messages.push(text);
+    sessionMessages.set(sessionID, messages);
+  };
+
+  const saveSessionSummary = async (sessionID: string) => {
+    const messages = sessionMessages.get(sessionID);
+    if (!messages || messages.length < 3) {
+      log("session-save: too few messages, skipping", { sessionID, count: messages?.length || 0 });
+      sessionMessages.delete(sessionID);
+      return;
+    }
+
+    // Build a condensed transcript (limit size)
+    const MAX_CHARS = 50_000;
+    let transcript = messages.join("\n---\n");
+    if (transcript.length > MAX_CHARS) {
+      transcript = transcript.slice(0, MAX_CHARS) + "\n...[truncated]";
+    }
+
+    const content = `[Session Conversation - ${new Date().toISOString()}]\n${transcript}`;
+
+    try {
+      const result = await supermemoryClient.ingestConversation(
+        sessionID,
+        [{ role: "user", content }],
+        [tags.project, tags.user],
+        { type: "conversation", source: "session-end" }
+      );
+      log("session-save: saved", { sessionID, success: result.success });
+    } catch (err) {
+      log("session-save: error", { sessionID, error: String(err) });
+    }
+
+    sessionMessages.delete(sessionID);
+  };
+
   return {
     "chat.message": async (input, output) => {
       if (!isConfigured()) return;
@@ -109,10 +155,13 @@ export const SupermemoryPlugin: Plugin = async (ctx: PluginInput) => {
           textPartsCount: textParts.length,
         });
 
+        // Track message for session-end auto-save
+        collectMessage(input.sessionID, userMessage);
+
         if (detectMemoryKeyword(userMessage)) {
           log("chat.message: memory keyword detected");
           const nudgePart: Part = {
-            id: `supermemory-nudge-${Date.now()}`,
+            id: generatePartId(),
             sessionID: input.sessionID,
             messageID: output.message.id,
             type: "text",
@@ -157,7 +206,7 @@ export const SupermemoryPlugin: Plugin = async (ctx: PluginInput) => {
 
           if (memoryContext) {
             const contextPart: Part = {
-              id: `supermemory-context-${Date.now()}`,
+              id: generatePartId(),
               sessionID: input.sessionID,
               messageID: output.message.id,
               type: "text",
@@ -485,6 +534,29 @@ export const SupermemoryPlugin: Plugin = async (ctx: PluginInput) => {
     },
 
     event: async (input: { event: { type: string; properties?: unknown } }) => {
+      // Auto-save session conversations on session end
+      if (input.event.type === "session.deleted" && isConfigured()) {
+        const props = input.event.properties as Record<string, unknown> | undefined;
+        const sessionInfo = props?.info as { id?: string } | undefined;
+        if (sessionInfo?.id) {
+          await saveSessionSummary(sessionInfo.id);
+        }
+      }
+
+      // Track assistant messages for richer session summaries
+      if (input.event.type === "message.updated" && isConfigured()) {
+        const props = input.event.properties as Record<string, unknown> | undefined;
+        const info = props?.info as { role?: string; sessionID?: string; finish?: boolean } | undefined;
+        if (info?.role === "assistant" && info?.finish && info?.sessionID) {
+          // Try to get assistant text from parts
+          const parts = props?.parts as Array<{ type: string; text?: string }> | undefined;
+          if (parts) {
+            const text = parts.filter(p => p.type === "text" && p.text).map(p => p.text!).join("\n");
+            if (text) collectMessage(info.sessionID, `[assistant] ${text}`);
+          }
+        }
+      }
+
       if (compactionHook) {
         await compactionHook.event(input);
       }
diff --git a/src/services/compaction.ts b/src/services/compaction.ts
index 4701beb..7bc2f09 100644
--- a/src/services/compaction.ts
+++ b/src/services/compaction.ts
@@ -4,6 +4,7 @@ import { homedir } from "node:os";
 import { supermemoryClient } from "./client.js";
 import { log } from "./logger.js";
 import { CONFIG } from "../config.js";
+import { generatePartId, generateMessageId } from "./ids.js";
 
 const MESSAGE_STORAGE = join(homedir(), ".opencode", "messages");
 const PART_STORAGE = join(homedir(), ".opencode", "parts");
@@ -152,18 +153,6 @@ function findNearestMessageWithFields(messageDir: string): StoredMessage | null
   return null;
 }
 
-function generateMessageId(): string {
-  const timestamp = Date.now().toString(16);
-  const random = Math.random().toString(36).substring(2, 14);
-  return `msg_${timestamp}${random}`;
-}
-
-function generatePartId(): string {
-  const timestamp = Date.now().toString(16);
-  const random = Math.random().toString(36).substring(2, 10);
-  return `prt_${timestamp}${random}`;
-}
-
 function injectHookMessage(
   sessionID: string,
   hookContent: string,
diff --git a/src/services/ids.ts b/src/services/ids.ts
new file mode 100644
index 0000000..7e7786e
--- /dev/null
+++ b/src/services/ids.ts
@@ -0,0 +1,16 @@
+/**
+ * Shared ID generation utilities.
+ * OpenCode v1.2.25+ requires all part IDs to start with "prt".
+ */
+
+export function generatePartId(): string {
+  const timestamp = Date.now().toString(16);
+  const random = Math.random().toString(36).substring(2, 10);
+  return `prt_${timestamp}${random}`;
+}
+
+export function generateMessageId(): string {
+  const timestamp = Date.now().toString(16);
+  const random = Math.random().toString(36).substring(2, 14);
+  return `msg_${timestamp}${random}`;
+}