fix session performance issue from large diffs

packages/opencode/src/server/server.ts

@@ -758,6 +758,34 @@ export namespace Server {
           return c.json(messages)
         },
       )
+      .get(
+        "/session/:id/diff",
+        describeRoute({
+          description: "Get the diff for this session",
+          operationId: "session.diff",
+          responses: {
+            200: {
+              description: "List of diffs",
+              content: {
+                "application/json": {
+                  schema: resolver(Snapshot.FileDiff.array()),
+                },
+              },
+            },
+            ...errors(400, 404),
+          },
+        }),
+        validator(
+          "param",
+          z.object({
+            id: z.string().meta({ description: "Session ID" }),
+          }),
+        ),
+        async (c) => {
+          const diff = await Session.diff(c.req.valid("param").id)
+          return c.json(diff)
+        },
+      )
       .get(
         "/session/:id/message/:messageID",
         describeRoute({

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[] }) {

packages/opencode/src/storage/storage.ts

@@ -85,7 +85,9 @@ export namespace Storage {
             const session = await Bun.file(sessionFile).json()
             await Bun.write(dest, JSON.stringify(session))
             log.info(`migrating messages for session ${session.id}`)
-            for await (const msgFile of new Bun.Glob(`storage/session/message/${session.id}/*.json`).scan({
+            for await (const msgFile of new Bun.Glob(
+              `storage/session/message/${session.id}/*.json`,
+            ).scan({
               cwd: fullProjectDir,
               absolute: true,
             })) {
@@ -98,12 +100,12 @@ export namespace Storage {
               await Bun.write(dest, JSON.stringify(message))
 
               log.info(`migrating parts for message ${message.id}`)
-              for await (const partFile of new Bun.Glob(`storage/session/part/${session.id}/${message.id}/*.json`).scan(
-                {
+              for await (const partFile of new Bun.Glob(
+                `storage/session/part/${session.id}/${message.id}/*.json`,
+              ).scan({
                 cwd: fullProjectDir,
                 absolute: true,
-                },
-              )) {
+              })) {
                 const dest = path.join(dir, "part", message.id, path.basename(partFile))
                 const part = await Bun.file(partFile).json()
                 log.info("copying", {
@@ -117,6 +119,29 @@ export namespace Storage {
         }
       }
     },
+    async (dir) => {
+      for await (const item of new Bun.Glob("session/*/*.json").scan({
+        cwd: dir,
+        absolute: true,
+      })) {
+        const session = await Bun.file(item).json()
+        if (!session.projectID) continue
+        if (!session.summary?.diffs) continue
+        const { diffs } = session.summary
+        await Bun.file(path.join(dir, "session_diff", session.id + ".json")).write(
+          JSON.stringify(diffs),
+        )
+        await Bun.file(path.join(dir, "session", session.projectID, session.id + ".json")).write(
+          JSON.stringify({
+            ...session,
+            summary: {
+              additions: diffs.reduce((sum: any, x: any) => sum + x.additions, 0),
+              deletions: diffs.reduce((sum: any, x: any) => sum + x.deletions, 0),
+            },
+          }),
+        )
+      }
+    },
   ]
 
   const state = lazy(async () => {
@@ -128,9 +153,7 @@ export namespace Storage {
     for (let index = migration; index < MIGRATIONS.length; index++) {
       log.info("running migration", { index })
       const migration = MIGRATIONS[index]
-      await migration(dir).catch((e) => {
-        log.error("failed to run migration", { error: e, index })
-      })
+      await migration(dir).catch(() => log.error("failed to run migration", { index }))
       await Bun.write(path.join(dir, "migration"), (index + 1).toString())
     }
     return {

packages/sdk/js/src/gen/sdk.gen.ts

@@ -55,6 +55,7 @@ import type {
   SessionShareErrors,
   SessionDiffData,
   SessionDiffResponses,
+  SessionDiffErrors,
   SessionSummarizeData,
   SessionSummarizeResponses,
   SessionSummarizeErrors,
@@ -475,12 +476,16 @@ class Session extends _HeyApiClient {
   }
 
   /**
-   * Get the diff that resulted from this user message
+   * Get the diff for this session
    */
   public diff<ThrowOnError extends boolean = false>(
     options: Options<SessionDiffData, ThrowOnError>,
   ) {
-    return (options.client ?? this._client).get<SessionDiffResponses, unknown, ThrowOnError>({
+    return (options.client ?? this._client).get<
+      SessionDiffResponses,
+      SessionDiffErrors,
+      ThrowOnError
+    >({
       url: "/session/{id}/diff",
       ...options,
     })

packages/sdk/js/src/gen/types.gen.ts

@@ -527,7 +527,9 @@ export type Session = {
   directory: string
   parentID?: string
   summary?: {
-    diffs: Array<FileDiff>
+    additions: number
+    deletions: number
+    diffs?: Array<FileDiff>
   }
   share?: {
     url: string
@@ -1882,6 +1884,9 @@ export type SessionShareResponse = SessionShareResponses[keyof SessionShareRespo
 export type SessionDiffData = {
   body?: never
   path: {
+    /**
+     * Session ID
+     */
     id: string
   }
   query?: {
@@ -1891,9 +1896,22 @@ export type SessionDiffData = {
   url: "/session/{id}/diff"
 }
 
+export type SessionDiffErrors = {
+  /**
+   * Bad request
+   */
+  400: BadRequestError
+  /**
+   * Not found
+   */
+  404: NotFoundError
+}
+
+export type SessionDiffError = SessionDiffErrors[keyof SessionDiffErrors]
+
 export type SessionDiffResponses = {
   /**
-   * Successfully retrieved diff
+   * List of diffs
    */
   200: Array<FileDiff>
 }