fix session performance issue from large diffs

packages/opencode/src/session/index.ts

@@ -15,8 +15,8 @@ import { MessageV2 } from "./message-v2"
 import { Instance } from "../project/instance"
 import { SessionPrompt } from "./prompt"
 import { fn } from "@/util/fn"
-import { Snapshot } from "@/snapshot"
 import { Command } from "../command"
+import { Snapshot } from "@/snapshot"
 
 export namespace Session {
   const log = Log.create({ service: "session" })
@@ -42,7 +42,9 @@ export namespace Session {
       parentID: Identifier.schema("session").optional(),
       summary: z
         .object({
-          diffs: Snapshot.FileDiff.array(),
+          additions: z.number(),
+          deletions: z.number(),
+          diffs: Snapshot.FileDiff.array().optional(),
         })
         .optional(),
       share: z
@@ -258,6 +260,11 @@ export namespace Session {
     return result
   }
 
+  export const diff = fn(Identifier.schema("session"), async (sessionID) => {
+    const diffs = await Storage.read<Snapshot.FileDiff[]>(["session_diff", sessionID])
+    return diffs ?? []
+  })
+
   export const messages = fn(Identifier.schema("session"), async (sessionID) => {
     const result = [] as MessageV2.WithParts[]
     for (const p of await Storage.list(["message", sessionID])) {

packages/opencode/src/session/summary.ts

@@ -11,6 +11,7 @@ import { SystemPrompt } from "./system"
 import { Log } from "@/util/log"
 import path from "path"
 import { Instance } from "@/project/instance"
+import { Storage } from "@/storage/storage"
 
 export namespace SessionSummary {
   const log = Log.create({ service: "session.summary" })
@@ -44,9 +45,11 @@ export namespace SessionSummary {
     )
     await Session.update(input.sessionID, (draft) => {
       draft.summary = {
-        diffs,
+        additions: diffs.reduce((sum, x) => sum + x.additions, 0),
+        deletions: diffs.reduce((sum, x) => sum + x.deletions, 0),
       }
     })
+    await Storage.write(["session_diff", input.sessionID], diffs)
   }
 
   async function summarizeMessage(input: { messageID: string; messages: MessageV2.WithParts[] }) {