core: add experimental turn summarization to compact conversation history

packages/opencode/src/session/summary.ts

@@ -0,0 +1,46 @@
+import { Provider } from "@/provider/provider"
+import { fn } from "@/util/fn"
+import z from "zod"
+import { Session } from "."
+import { generateText } from "ai"
+import { MessageV2 } from "./message-v2"
+import SUMMARIZE_TURN from "./prompt/summarize-turn.txt"
+import { Flag } from "@/flag/flag"
+
+export namespace MessageSummary {
+  export const summarize = fn(
+    z.object({
+      sessionID: z.string(),
+      messageID: z.string(),
+      providerID: z.string(),
+    }),
+    async (input) => {
+      if (!Flag.OPENCODE_EXPERIMENTAL_TURN_SUMMARY) return
+      const messages = await Session.messages(input.sessionID).then((msgs) =>
+        msgs.filter(
+          (m) => m.info.id === input.messageID || (m.info.role === "assistant" && m.info.parentID === input.messageID),
+        ),
+      )
+      const small = await Provider.getSmallModel(input.providerID)
+      if (!small) return
+
+      const result = await generateText({
+        model: small.language,
+        messages: [
+          {
+            role: "system",
+            content: SUMMARIZE_TURN,
+          },
+          ...MessageV2.toModelMessage(messages),
+        ],
+      })
+
+      const userMsg = messages.find((m) => m.info.id === input.messageID)!
+      userMsg.info.summary = {
+        text: result.text,
+        diffs: [],
+      }
+      await Session.updateMessage(userMsg.info)
+    },
+  )
+}