diff --git a/packages/opencode/src/session/revert.ts b/packages/opencode/src/session/revert.ts
index ef9c7e2aace9..ada4f82bfd57 100644
--- a/packages/opencode/src/session/revert.ts
+++ b/packages/opencode/src/session/revert.ts
@@ -56,11 +56,21 @@ export namespace SessionRevert {
 
     if (revert) {
       const session = await Session.get(input.sessionID)
-      revert.snapshot = session.revert?.snapshot ?? (await Snapshot.track())
+      const snapshot = session.revert?.snapshot ?? (await Snapshot.track())
+      // When stacking reverts, ensure we restore the original snapshot baseline so the
+      // next diff only reflects the newly reverted content, not prior revert state.
+      if (session.revert?.snapshot) await Snapshot.restore(session.revert.snapshot)
+      // Preserve the baseline snapshot for future redo/unrevert operations.
+      revert.snapshot = snapshot
       await Snapshot.revert(patches)
       if (revert.snapshot) revert.diff = await Snapshot.diff(revert.snapshot)
-      const rangeMessages = all.filter((msg) => msg.info.id >= revert!.messageID)
-      const diffs = await SessionSummary.computeDiff({ messages: rangeMessages })
+      const remainingMessages = all.filter((msg) =>
+        revert?.partID ? msg.info.id <= revert.messageID : msg.info.id < revert!.messageID,
+      )
+      // Make sure new summary is made up of remainingMessgaes, messages with id less (<) then the reverted one
+      // If reverting a part, we add in the message itself
+
+      const diffs = await SessionSummary.computeDiff({ messages: remainingMessages })
       await Storage.write(["session_diff", input.sessionID], diffs)
       Bus.publish(Session.Event.Diff, {
         sessionID: input.sessionID,
@@ -85,6 +95,23 @@ export namespace SessionRevert {
     const session = await Session.get(input.sessionID)
     if (!session.revert) return session
     if (session.revert.snapshot) await Snapshot.restore(session.revert.snapshot)
+    const messages = await Session.messages({ sessionID: input.sessionID })
+    const diffs = await SessionSummary.computeDiff({ messages })
+    await Storage.write(["session_diff", input.sessionID], diffs)
+    Bus.publish(Session.Event.Diff, {
+      sessionID: input.sessionID,
+      diff: diffs,
+    })
+
+    await Session.setSummary({
+      sessionID: input.sessionID,
+      summary: {
+        ...session.summary,
+        additions: diffs.reduce((sum, x) => sum + x.additions, 0),
+        deletions: diffs.reduce((sum, x) => sum + x.deletions, 0),
+        files: diffs.length,
+      },
+    })
     return Session.clearRevert(input.sessionID)
   }