refactor(opencode): cache compaction boundary to skip redundant DB reads

packages/opencode/src/session/compaction.ts

@@ -366,6 +366,7 @@ When constructing the summary, try to stick to this template:
           auto: input.auto,
           overflow: input.overflow,
         })
+        MessageV2.invalidateCompactionBoundary(input.sessionID)
       })
 
       return Service.of({

packages/opencode/src/session/message-v2.ts

@@ -6,7 +6,7 @@ import { APICallError, convertToModelMessages, LoadAPIKeyError, type ModelMessag
 import { LSP } from "../lsp"
 import { Snapshot } from "@/snapshot"
 import { SyncEvent } from "../sync"
-import { Database, NotFoundError, and, desc, eq, inArray, lt, or } from "@/storage/db"
+import { Database, NotFoundError, and, desc, eq, gt, gte, inArray, lt, or } from "@/storage/db"
 import { MessageTable, PartTable, SessionTable } from "./session.sql"
 import { ProviderError } from "@/provider/error"
 import { iife } from "@/util/iife"
@@ -550,6 +550,12 @@ export namespace MessageV2 {
       and(eq(MessageTable.time_created, row.time), lt(MessageTable.id, row.id)),
     )
 
+  const newerOrEqual = (row: Cursor) =>
+    or(
+      gt(MessageTable.time_created, row.time),
+      and(eq(MessageTable.time_created, row.time), gte(MessageTable.id, row.id)),
+    )
+
   function hydrate(rows: (typeof MessageTable.$inferSelect)[]) {
     const ids = rows.map((row) => row.id)
     const partByMessage = new Map<string, MessageV2.Part[]>()
@@ -845,11 +851,12 @@ export namespace MessageV2 {
     return Effect.runPromise(toModelMessagesEffect(input, model, options).pipe(Effect.provide(EffectLogger.layer)))
   }
 
-  export function page(input: { sessionID: SessionID; limit: number; before?: string }) {
+  export function page(input: { sessionID: SessionID; limit: number; before?: string; since?: Cursor }) {
     const before = input.before ? cursor.decode(input.before) : undefined
-    const where = before
+    let where = before
       ? and(eq(MessageTable.session_id, input.sessionID), older(before))
       : eq(MessageTable.session_id, input.sessionID)
+    if (input.since) where = and(where, newerOrEqual(input.since))
     const rows = Database.use((db) =>
       db
         .select()
@@ -882,11 +889,11 @@ export namespace MessageV2 {
     }
   }
 
-  export function* stream(sessionID: SessionID) {
+  export function* stream(sessionID: SessionID, since?: Cursor) {
     const size = 50
     let before: string | undefined
     while (true) {
-      const next = page({ sessionID, limit: size, before })
+      const next = page({ sessionID, limit: size, before, since })
       if (next.items.length === 0) break
       for (let i = next.items.length - 1; i >= 0; i--) {
         yield next.items[i]
@@ -944,8 +951,32 @@ export namespace MessageV2 {
     return result
   }
 
+  // Cache compaction boundaries per session to avoid re-reading pre-compaction messages.
+  // Capped at MAX_BOUNDARY_CACHE entries; oldest entry evicted on insert when full.
+  const MAX_BOUNDARY_CACHE = 1000
+  const compactionBoundary = new Map<string, Cursor>()
+
+  function setCompactionBoundary(sessionID: string, cursor: Cursor) {
+    if (!compactionBoundary.has(sessionID) && compactionBoundary.size >= MAX_BOUNDARY_CACHE) {
+      const oldest = compactionBoundary.keys().next().value
+      if (oldest !== undefined) compactionBoundary.delete(oldest)
+    }
+    compactionBoundary.set(sessionID, cursor)
+  }
+
+  export function invalidateCompactionBoundary(sessionID?: string) {
+    if (sessionID) compactionBoundary.delete(sessionID)
+    else compactionBoundary.clear()
+  }
+
   export const filterCompactedEffect = Effect.fnUntraced(function* (sessionID: SessionID) {
-    return filterCompacted(stream(sessionID))
+    const cached = compactionBoundary.get(sessionID)
+    const msgs = filterCompacted(stream(sessionID, cached))
+    if (msgs.length > 0) {
+      const first = msgs[0]
+      setCompactionBoundary(sessionID, { id: first.info.id, time: first.info.time.created })
+    }
+    return msgs
   })
 
   export function fromError(