From c87f6b710ec0370ad2bb2193ce09a309c8d068f0 Mon Sep 17 00:00:00 2001
From: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>
Date: Wed, 21 Oct 2026 20:01:10 -0500
Subject: [PATCH] fix(core): validate compaction keepID with SessionMessage.ID
 schema (#57945)

---
 packages/core/src/session/history.ts          | 12 +++---
 packages/core/src/session/projector.ts        |  9 +----
 packages/core/test/session-compaction.test.ts | 37 +++++++++++++++++++
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/packages/core/src/session/history.ts b/packages/core/src/session/history.ts
index 74159a27b2b..6b96d00306a 100644
--- a/packages/core/src/session/history.ts
+++ b/packages/core/src/session/history.ts
@@ -6,7 +6,7 @@ import { SessionLegacy } from "@opencode/schema/session-legacy"
 import { Database } from "../database/database.js"
 import { MessageDecodeError } from "./error.js"
 import { SessionMessage } from "./message.js"
-import { SessionSchema } from "./schema.js"
+import type { SessionSchema } from "./schema.js"
 import { Instructions } from "../instructions/index.js"
 import { InstructionState } from "./instruction-state.js"
 import { SessionRecentText } from "./recent-text.js"
@@ -93,8 +93,8 @@ export const decodeMessageRow = (row: typeof SessionMessageTable.$inferSelect) =
     Effect.mapError(
       () =>
         new MessageDecodeError({
-          sessionID: SessionSchema.ID.make(row.session_id),
-          messageID: SessionMessage.ID.make(row.id),
+          sessionID: row.session_id,
+          messageID: row.id,
         }),
     ),
   )
@@ -154,13 +154,11 @@ const withRecentText = Effect.fnUntraced(function* (
   const compaction = first?.message
   if (compaction?.type !== "compaction" || compaction.status !== "completed") return entries
   const keepID = compaction.metadata?.keepID
-  if (typeof keepID !== "string") return entries
+  if (!Schema.is(SessionMessage.ID)(keepID)) return entries
   const start = yield* db
     .select({ seq: SessionMessageTable.seq })
     .from(SessionMessageTable)
-    .where(
-      and(eq(SessionMessageTable.session_id, sessionID), eq(SessionMessageTable.id, SessionMessage.ID.make(keepID))),
-    )
+    .where(and(eq(SessionMessageTable.session_id, sessionID), eq(SessionMessageTable.id, keepID)))
     .get()
     .pipe(Effect.orDie)
   if (!start) return entries
diff --git a/packages/core/src/session/projector.ts b/packages/core/src/session/projector.ts
index 86b6eed40d8..29d3c9b1477 100644
--- a/packages/core/src/session/projector.ts
+++ b/packages/core/src/session/projector.ts
@@ -224,16 +224,11 @@ const projectFork = Effect.fn("SessionProjector.projectFork")(function* (
         }
         // A summary references the first message it kept, which the fork copied under a new ID.
         const keepID = row.type === "compaction" ? row.data.metadata?.keepID : undefined
-        if (typeof keepID !== "string") return copy
+        if (!Schema.is(SessionMessage.ID)(keepID)) return copy
         const kept = yield* db
           .select({ seq: SessionMessageTable.seq })
           .from(SessionMessageTable)
-          .where(
-            and(
-              eq(SessionMessageTable.session_id, event.data.parentID),
-              eq(SessionMessageTable.id, SessionMessage.ID.make(keepID)),
-            ),
-          )
+          .where(and(eq(SessionMessageTable.session_id, event.data.parentID), eq(SessionMessageTable.id, keepID)))
           .get()
           .pipe(Effect.orDie)
         if (!kept) return copy
diff --git a/packages/core/test/session-compaction.test.ts b/packages/core/test/session-compaction.test.ts
index bd7bd3029f6..85eb563db4c 100644
--- a/packages/core/test/session-compaction.test.ts
+++ b/packages/core/test/session-compaction.test.ts
@@ -199,6 +199,43 @@ it.effect("forks rebuild the recent text of a summary they copied", () =>
   }),
 )
 
+it.effect("ignores non-message keepID strings when loading history or forking", () =>
+  Effect.gen(function* () {
+    const parentID = Session.ID.make("ses_invalid_keepid_parent")
+    const childID = Session.ID.make("ses_invalid_keepid_child")
+    yield* insertSession(parentID)
+    const compaction = SessionMessage.CompactionCompleted.make({
+      id: SessionMessage.ID.create(),
+      type: "compaction",
+      status: "completed",
+      reason: "manual",
+      summary: "## Objective\n- plugin summary",
+      metadata: { keepID: "not-a-msg-id" },
+      time: { created: DateTime.makeUnsafe(0) },
+    })
+    yield* storeMessages(parentID, [textUser("Earlier question"), compaction])
+
+    const store = yield* SessionStore.Service
+    const [parent] = yield* store.context(parentID)
+    expect(parent).toMatchObject({
+      type: "compaction",
+      metadata: { keepID: "not-a-msg-id" },
+    })
+
+    const bus = yield* Bus.Service
+    yield* bus.publish(SessionEvent.Forked, {
+      sessionID: childID,
+      parentID,
+      boundary: { type: "through", messageID: compaction.id },
+    })
+    const [child] = yield* store.context(childID)
+    expect(child).toMatchObject({
+      type: "compaction",
+      metadata: { keepID: "not-a-msg-id" },
+    })
+  }),
+)
+
 const textUser = (text: string) =>
   SessionMessage.User.make({
     id: SessionMessage.ID.create(),