diff --git a/packages/opencode/src/session/processor.ts b/packages/opencode/src/session/processor.ts
index 225961aef05d..06784ab29968 100644
--- a/packages/opencode/src/session/processor.ts
+++ b/packages/opencode/src/session/processor.ts
@@ -312,10 +312,6 @@ export namespace SessionProcessor {
                 }
                 ctx.snapshot = undefined
               }
-              SessionSummary.summarize({
-                sessionID: ctx.sessionID,
-                messageID: ctx.assistantMessage.parentID,
-              })
               if (
                 !ctx.assistantMessage.summary &&
                 isOverflow({ cfg: yield* config.get(), tokens: usage.tokens, model: ctx.model })
diff --git a/packages/opencode/src/session/summary.ts b/packages/opencode/src/session/summary.ts
index f2b53f3baf58..3ea2772e0f75 100644
--- a/packages/opencode/src/session/summary.ts
+++ b/packages/opencode/src/session/summary.ts
@@ -4,9 +4,11 @@ import { makeRuntime } from "@/effect/run-service"
 import { Bus } from "@/bus"
 import { Snapshot } from "@/snapshot"
 import { Storage } from "@/storage/storage"
+import { Database, and, eq } from "@/storage/db"
 import { Session } from "."
 import { MessageV2 } from "./message-v2"
 import { SessionID, MessageID } from "./schema"
+import { MessageTable } from "./session.sql"
 
 export namespace SessionSummary {
   function unquoteGitPath(input: string) {
@@ -107,6 +109,15 @@ export namespace SessionSummary {
         sessionID: SessionID
         messageID: MessageID
       }) {
+        const row = Database.use((db) =>
+          db
+            .select({ data: MessageTable.data })
+            .from(MessageTable)
+            .where(and(eq(MessageTable.id, input.messageID), eq(MessageTable.session_id, input.sessionID)))
+            .get(),
+        )
+        const summary = row?.data.summary
+        if (summary && typeof summary === "object" && "diffs" in summary && summary.diffs) return
         const all = yield* sessions.messages({ sessionID: input.sessionID })
         if (!all.length) return
 
diff --git a/packages/opencode/test/session/prompt-effect.test.ts b/packages/opencode/test/session/prompt-effect.test.ts
index 38d7ed9f5aca..36a573ab054e 100644
--- a/packages/opencode/test/session/prompt-effect.test.ts
+++ b/packages/opencode/test/session/prompt-effect.test.ts
@@ -26,6 +26,7 @@ import { Instruction } from "../../src/session/instruction"
 import { SessionProcessor } from "../../src/session/processor"
 import { SessionPrompt } from "../../src/session/prompt"
 import { MessageID, PartID, SessionID } from "../../src/session/schema"
+import { SessionSummary } from "../../src/session/summary"
 import { SessionStatus } from "../../src/session/status"
 import { Shell } from "../../src/shell/shell"
 import { Snapshot } from "../../src/snapshot"
@@ -459,6 +460,42 @@ it.live("loop continues when finish is tool-calls", () =>
   ),
 )
 
+it.live("loop summarizes once across a multi-step tool run", () =>
+  provideTmpdirServer(
+    Effect.fnUntraced(function* ({ llm }) {
+      const prompt = yield* SessionPrompt.Service
+      const sessions = yield* Session.Service
+      const session = yield* sessions.create({
+        title: "Pinned",
+        permission: [{ permission: "*", pattern: "*", action: "allow" }],
+      })
+      let summaries = 0
+      const runtime = SessionSummary as unknown as { summarize: typeof SessionSummary.summarize }
+      const original = runtime.summarize
+      runtime.summarize = (input) => {
+        summaries++
+        return original(input)
+      }
+      yield* prompt.prompt({
+        sessionID: session.id,
+        agent: "build",
+        noReply: true,
+        parts: [{ type: "text", text: "hello" }],
+      })
+      yield* llm.tool("first", { value: "first" })
+      yield* llm.text("second")
+
+      const result = yield* prompt.loop({ sessionID: session.id })
+      runtime.summarize = original
+
+      expect(yield* llm.calls).toBe(2)
+      expect(result.info.role).toBe("assistant")
+      expect(summaries).toBe(1)
+    }),
+    { git: true, config: providerCfg },
+  ),
+)
+
 it.live("loop continues when finish is stop but assistant has tool parts", () =>
   provideTmpdirServer(
     Effect.fnUntraced(function* ({ llm }) {