fix(opencode): use chronological message boundaries (#40991)

Co-authored-by: Dax <mail@thdxr.com>

packages/opencode/src/session/revert.ts

@@ -71,7 +71,8 @@ const layer = Layer.effect(
       if (session.revert?.snapshot) yield* snap.restore(session.revert.snapshot)
       yield* snap.revert(patches)
       if (rev.snapshot) rev.diff = yield* snap.diff(rev.snapshot)
-      const range = all.filter((msg) => msg.info.id >= rev.messageID)
+      const index = all.findIndex((msg) => msg.info.id === rev.messageID)
+      const range = index < 0 ? [] : all.slice(index)
       const diffs = yield* summary.computeDiff({ messages: range })
       yield* storage.write(["session_diff", input.sessionID], diffs).pipe(Effect.ignore)
       yield* events.publish(Session.Event.Diff, { sessionID: input.sessionID, diff: diffs })
@@ -102,20 +103,9 @@ const layer = Layer.effect(
       const sessionID = session.id
       const msgs = yield* sessions.messages({ sessionID }).pipe(Effect.orDie)
       const messageID = session.revert.messageID
-      const remove = [] as SessionV1.WithParts[]
-      let target: SessionV1.WithParts | undefined
-      for (const msg of msgs) {
-        if (msg.info.id < messageID) continue
-        if (msg.info.id > messageID) {
-          remove.push(msg)
-          continue
-        }
-        if (session.revert.partID) {
-          target = msg
-          continue
-        }
-        remove.push(msg)
-      }
+      const index = msgs.findIndex((msg) => msg.info.id === messageID)
+      const target = index < 0 ? undefined : msgs[index]
+      const remove = index < 0 ? [] : msgs.slice(index + (session.revert.partID ? 1 : 0))
       for (const msg of remove) {
         yield* sessions.removeMessage({ sessionID, messageID: msg.info.id })
       }

packages/opencode/src/session/session.ts

@@ -703,9 +703,9 @@ const layer: Layer.Layer<
       })
       const msgs = yield* messages({ sessionID: input.sessionID })
       const idMap = new Map<string, MessageID>()
+      const target = input.messageID ? msgs.findIndex((msg) => msg.info.id === input.messageID) : msgs.length
 
-      for (const msg of msgs) {
-        if (input.messageID && msg.info.id >= input.messageID) break
+      for (const msg of msgs.slice(0, target < 0 ? msgs.length : target)) {
         const newID = MessageID.ascending()
         idMap.set(msg.info.id, newID)