fix(opencode): remove automatic full session diffs (#30127)

packages/opencode/test/server/session-diff-missing-patch.test.ts

@@ -4,16 +4,20 @@
  * the response was Schema-encoded against `Snapshot.FileDiff` with
  * `patch: Schema.String` (required), so any session whose stored
  * `summary_diffs` had a row without `patch` returned HTTP 400 and the
- * session never loaded.
+ * session never loaded. Legacy session-level diffs are no longer surfaced,
+ * but the endpoint remains compatible and must still return successfully.
  *
  * This test inserts a session row with a missing-patch diff entry and
- * asserts that GET /session/<id>/diff returns 200 with the row intact.
+ * asserts that GET /session/<id>/diff returns 200 with empty data.
  */
 import { afterEach, describe, expect } from "bun:test"
 import { Effect, Layer } from "effect"
 import { SessionPaths } from "@/server/routes/instance/httpapi/groups/session"
 import { Session } from "@/session/session"
 import { Storage } from "@/storage/storage"
+import { SessionLegacy } from "@opencode-ai/core/session/legacy"
+import { MessageID } from "@/session/schema"
+import { ProviderV2 } from "@opencode-ai/core/provider"
 import { resetDatabase } from "../fixture/db"
 import { disposeAllInstances, TestInstance } from "../fixture/fixture"
 import { testEffect } from "../lib/effect"
@@ -38,7 +42,7 @@ const withSession = (input?: Parameters<Session.Interface["create"]>[0]) =>
 
 describe("session diff with missing patch (#26574)", () => {
   it.instance(
-    "GET /session/<id>/diff returns 200 when summary_diffs row has no patch",
+    "GET /session/<id>/diff ignores legacy session-level diff storage",
     () =>
       Effect.gen(function* () {
         const test = yield* TestInstance
@@ -57,15 +61,37 @@ describe("session diff with missing patch (#26574)", () => {
         )
 
         expect(response.status).toBe(200)
-        const body = (yield* response.json) as Array<{
-          file: string
-          patch?: string
-          additions: number
-        }>
-        expect(body).toHaveLength(1)
-        expect(body[0]?.file).toBe("legacy.txt")
-        expect(body[0]?.additions).toBe(1)
-        expect(body[0]?.patch).toBeUndefined()
+        expect(yield* response.json).toEqual([])
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
+  it.instance(
+    "GET /session/<id>/diff returns requested turn diffs",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "turn-diff" })
+        const messageID = MessageID.ascending()
+        yield* Session.use.updateMessage({
+          id: messageID,
+          sessionID: session.id,
+          role: "user",
+          time: { created: Date.now() },
+          agent: "build",
+          model: { providerID: ProviderV2.ID.make("test"), modelID: ProviderV2.ModelID.make("model") },
+          summary: {
+            diffs: [{ file: "turn.ts", additions: 1, deletions: 0, status: "modified" }],
+          },
+        } satisfies SessionLegacy.User)
+
+        const response = yield* requestInDirectory(
+          `${pathFor(SessionPaths.diff, { sessionID: session.id })}?messageID=${messageID}`,
+          test.directory,
+        )
+
+        expect(response.status).toBe(200)
+        expect(yield* response.json).toEqual([{ file: "turn.ts", additions: 1, deletions: 0, status: "modified" }])
       }),
     { git: true, config: { formatter: false, lsp: false } },
   )