refactor: add Effect-returning versions of MessageV2 functions

Extract sync cores (partsSync, getSync, pageSync) from MessageV2 DB
functions and add Effect.fn wrappers: partsEffect, getEffect, pageEffect,
streamEffect, filterCompactedEffect, toModelMessagesEffect.

Replace all Effect.promise(() => MessageV2.*) call sites in processor,
prompt, compaction, session index, and tests with direct yield* calls.

packages/opencode/src/session/compaction.ts

@@ -218,7 +218,7 @@ When constructing the summary, try to stick to this template:
         const prompt = compacting.prompt ?? [defaultPrompt, ...compacting.context].join("\n\n")
         const msgs = structuredClone(messages)
         yield* plugin.trigger("experimental.chat.messages.transform", {}, { messages: msgs })
-        const modelMessages = yield* Effect.promise(() => MessageV2.toModelMessages(msgs, model, { stripMedia: true }))
+        const modelMessages = yield* MessageV2.toModelMessagesEffect(msgs, model, { stripMedia: true })
         const ctx = yield* InstanceState.context
         const msg: MessageV2.Assistant = {
           id: MessageID.ascending(),

packages/opencode/src/session/index.ts

@@ -593,15 +593,13 @@ export namespace Session {
       })
 
       const messages = Effect.fn("Session.messages")(function* (input: { sessionID: SessionID; limit?: number }) {
-        return yield* Effect.promise(async () => {
-          const result = [] as MessageV2.WithParts[]
-          for await (const msg of MessageV2.stream(input.sessionID)) {
-            if (input.limit && result.length >= input.limit) break
-            result.push(msg)
-          }
-          result.reverse()
-          return result
-        })
+        if (input.limit) {
+          const result = yield* MessageV2.pageEffect({ sessionID: input.sessionID, limit: input.limit })
+          return result.items
+        }
+        const all = yield* MessageV2.streamEffect(input.sessionID)
+        all.reverse()
+        return all
       })
 
       const removeMessage = Effect.fn("Session.removeMessage")(function* (input: {

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

@@ -15,6 +15,7 @@ import { errorMessage } from "@/util/error"
 import type { SystemError } from "bun"
 import type { Provider } from "@/provider/provider"
 import { ModelID, ProviderID } from "@/provider/schema"
+import { Effect } from "effect"
 
 /** Error shape thrown by Bun's fetch() when gzip/br decompression fails mid-stream */
 interface FetchDecompressionError extends Error {
@@ -547,7 +548,7 @@ export namespace MessageV2 {
       and(eq(MessageTable.time_created, row.time), lt(MessageTable.id, row.id)),
     )
 
-  async function hydrate(rows: (typeof MessageTable.$inferSelect)[]) {
+  function hydrate(rows: (typeof MessageTable.$inferSelect)[]) {
     const ids = rows.map((row) => row.id)
     const partByMessage = new Map<string, MessageV2.Part[]>()
     if (ids.length > 0) {
@@ -809,48 +810,58 @@ export namespace MessageV2 {
     )
   }
 
+  export const toModelMessagesEffect = Effect.fnUntraced(function* (
+    input: WithParts[],
+    model: Provider.Model,
+    options?: { stripMedia?: boolean },
+  ) {
+    return yield* Effect.promise(() => toModelMessages(input, model, options))
+  })
+
+  function pageSync(input: { sessionID: SessionID; limit: number; before?: string }) {
+    const before = input.before ? cursor.decode(input.before) : undefined
+    const where = before
+      ? and(eq(MessageTable.session_id, input.sessionID), older(before))
+      : eq(MessageTable.session_id, input.sessionID)
+    const rows = Database.use((db) =>
+      db
+        .select()
+        .from(MessageTable)
+        .where(where)
+        .orderBy(desc(MessageTable.time_created), desc(MessageTable.id))
+        .limit(input.limit + 1)
+        .all(),
+    )
+    if (rows.length === 0) {
+      const row = Database.use((db) =>
+        db.select({ id: SessionTable.id }).from(SessionTable).where(eq(SessionTable.id, input.sessionID)).get(),
+      )
+      if (!row) throw new NotFoundError({ message: `Session not found: ${input.sessionID}` })
+      return {
+        items: [] as MessageV2.WithParts[],
+        more: false,
+      }
+    }
+
+    const more = rows.length > input.limit
+    const slice = more ? rows.slice(0, input.limit) : rows
+    const items = hydrate(slice)
+    items.reverse()
+    const tail = slice.at(-1)
+    return {
+      items,
+      more,
+      cursor: more && tail ? cursor.encode({ id: tail.id, time: tail.time_created }) : undefined,
+    }
+  }
+
   export const page = fn(
     z.object({
       sessionID: SessionID.zod,
       limit: z.number().int().positive(),
       before: z.string().optional(),
     }),
-    async (input) => {
-      const before = input.before ? cursor.decode(input.before) : undefined
-      const where = before
-        ? and(eq(MessageTable.session_id, input.sessionID), older(before))
-        : eq(MessageTable.session_id, input.sessionID)
-      const rows = Database.use((db) =>
-        db
-          .select()
-          .from(MessageTable)
-          .where(where)
-          .orderBy(desc(MessageTable.time_created), desc(MessageTable.id))
-          .limit(input.limit + 1)
-          .all(),
-      )
-      if (rows.length === 0) {
-        const row = Database.use((db) =>
-          db.select({ id: SessionTable.id }).from(SessionTable).where(eq(SessionTable.id, input.sessionID)).get(),
-        )
-        if (!row) throw new NotFoundError({ message: `Session not found: ${input.sessionID}` })
-        return {
-          items: [] as MessageV2.WithParts[],
-          more: false,
-        }
-      }
-
-      const more = rows.length > input.limit
-      const page = more ? rows.slice(0, input.limit) : rows
-      const items = await hydrate(page)
-      items.reverse()
-      const tail = page.at(-1)
-      return {
-        items,
-        more,
-        cursor: more && tail ? cursor.encode({ id: tail.id, time: tail.time_created }) : undefined,
-      }
-    },
+    async (input) => pageSync(input),
   )
 
   export const stream = fn(SessionID.zod, async function* (sessionID) {
@@ -867,7 +878,7 @@ export namespace MessageV2 {
     }
   })
 
-  export const parts = fn(MessageID.zod, async (message_id) => {
+  function partsSync(message_id: MessageID) {
     const rows = Database.use((db) =>
       db.select().from(PartTable).where(eq(PartTable.message_id, message_id)).orderBy(PartTable.id).all(),
     )
@@ -880,29 +891,83 @@ export namespace MessageV2 {
           messageID: row.message_id,
         }) as MessageV2.Part,
     )
-  })
+  }
+
+  export const parts = fn(MessageID.zod, async (message_id) => partsSync(message_id))
+
+  function getSync(input: { sessionID: SessionID; messageID: MessageID }): WithParts {
+    const row = Database.use((db) =>
+      db
+        .select()
+        .from(MessageTable)
+        .where(and(eq(MessageTable.id, input.messageID), eq(MessageTable.session_id, input.sessionID)))
+        .get(),
+    )
+    if (!row) throw new NotFoundError({ message: `Message not found: ${input.messageID}` })
+    return {
+      info: info(row),
+      parts: partsSync(input.messageID),
+    }
+  }
 
   export const get = fn(
     z.object({
       sessionID: SessionID.zod,
       messageID: MessageID.zod,
     }),
-    async (input): Promise<WithParts> => {
-      const row = Database.use((db) =>
-        db
-          .select()
-          .from(MessageTable)
-          .where(and(eq(MessageTable.id, input.messageID), eq(MessageTable.session_id, input.sessionID)))
-          .get(),
-      )
-      if (!row) throw new NotFoundError({ message: `Message not found: ${input.messageID}` })
-      return {
-        info: info(row),
-        parts: await parts(input.messageID),
-      }
-    },
+    async (input): Promise<WithParts> => getSync(input),
   )
 
+  export const partsEffect = Effect.fnUntraced(function* (id: MessageID) {
+    return partsSync(id)
+  })
+
+  export const getEffect = Effect.fnUntraced(function* (input: { sessionID: SessionID; messageID: MessageID }) {
+    return getSync(input)
+  })
+
+  export const pageEffect = Effect.fnUntraced(function* (input: {
+    sessionID: SessionID
+    limit: number
+    before?: string
+  }) {
+    return pageSync(input)
+  })
+
+  export const streamEffect = Effect.fnUntraced(function* (sessionID: SessionID) {
+    const result: WithParts[] = []
+    const size = 50
+    let before: string | undefined
+    while (true) {
+      const next = pageSync({ sessionID, limit: size, before })
+      if (next.items.length === 0) break
+      for (let i = next.items.length - 1; i >= 0; i--) {
+        result.push(next.items[i])
+      }
+      if (!next.more || !next.cursor) break
+      before = next.cursor
+    }
+    return result
+  })
+
+  function applyCompactionFilter(msgs: MessageV2.WithParts[]) {
+    const result = [] as MessageV2.WithParts[]
+    const completed = new Set<string>()
+    for (const msg of msgs) {
+      result.push(msg)
+      if (
+        msg.info.role === "user" &&
+        completed.has(msg.info.id) &&
+        msg.parts.some((part) => part.type === "compaction")
+      )
+        break
+      if (msg.info.role === "assistant" && msg.info.summary && msg.info.finish && !msg.info.error)
+        completed.add(msg.info.parentID)
+    }
+    result.reverse()
+    return result
+  }
+
   export async function filterCompacted(stream: AsyncIterable<MessageV2.WithParts>) {
     const result = [] as MessageV2.WithParts[]
     const completed = new Set<string>()
@@ -921,6 +986,10 @@ export namespace MessageV2 {
     return result
   }
 
+  export const filterCompactedEffect = Effect.fnUntraced(function* (sessionID: SessionID) {
+    return applyCompactionFilter(yield* streamEffect(sessionID))
+  })
+
   export function fromError(
     e: unknown,
     ctx: { providerID: ProviderID; aborted?: boolean },

packages/opencode/src/session/processor.ts

@@ -180,7 +180,7 @@ export namespace SessionProcessor {
                 metadata: value.providerMetadata,
               } satisfies MessageV2.ToolPart)
 
-              const parts = yield* Effect.promise(() => MessageV2.parts(ctx.assistantMessage.id))
+              const parts = yield* MessageV2.partsEffect(ctx.assistantMessage.id)
               const recentParts = parts.slice(-DOOM_LOOP_THRESHOLD)
 
               if (
@@ -392,7 +392,7 @@ export namespace SessionProcessor {
           }
           ctx.reasoningMap = {}
 
-          const parts = yield* Effect.promise(() => MessageV2.parts(ctx.assistantMessage.id))
+          const parts = yield* MessageV2.partsEffect(ctx.assistantMessage.id)
           for (const part of parts) {
             if (part.type !== "tool" || part.state.status === "completed" || part.state.status === "error") continue
             yield* session.updatePart({

packages/opencode/src/session/prompt.ts

@@ -213,7 +213,7 @@ export namespace SessionPrompt {
             (yield* provider.getModel(input.providerID, input.modelID)))
         const msgs = onlySubtasks
           ? [{ role: "user" as const, content: subtasks.map((p) => p.prompt).join("\n") }]
-          : yield* Effect.promise(() => MessageV2.toModelMessages(context, mdl))
+          : yield* MessageV2.toModelMessagesEffect(context, mdl)
         const text = yield* Effect.promise(async (signal) => {
           const result = await LLM.stream({
             agent: ag,
@@ -1360,7 +1360,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
             yield* status.set(sessionID, { type: "busy" })
             log.info("loop", { step, sessionID })
 
-            let msgs = yield* Effect.promise(() => MessageV2.filterCompacted(MessageV2.stream(sessionID)))
+            let msgs = yield* MessageV2.filterCompactedEffect(sessionID)
 
             let lastUser: MessageV2.User | undefined
             let lastAssistant: MessageV2.Assistant | undefined

packages/opencode/test/session/processor-effect.test.ts

@@ -207,7 +207,7 @@ it.live("session.processor effect tests capture llm input cleanly", () =>
         } satisfies LLM.StreamInput
 
         const value = yield* handle.process(input)
-        const parts = yield* Effect.promise(() => MessageV2.parts(msg.id))
+        const parts = yield* MessageV2.partsEffect(msg.id)
         const calls = yield* llm.calls
 
         expect(value).toBe("continue")
@@ -254,7 +254,7 @@ it.live("session.processor effect tests stop after token overflow requests compa
           tools: {},
         })
 
-        const parts = yield* Effect.promise(() => MessageV2.parts(msg.id))
+        const parts = yield* MessageV2.partsEffect(msg.id)
 
         expect(value).toBe("compact")
         expect(parts.some((part) => part.type === "text" && part.text === "after")).toBe(true)
@@ -347,7 +347,7 @@ it.live("session.processor effect tests reset reasoning state across retries", (
           tools: {},
         })
 
-        const parts = yield* Effect.promise(() => MessageV2.parts(msg.id))
+        const parts = yield* MessageV2.partsEffect(msg.id)
         const reasoning = parts.filter((part): part is MessageV2.ReasoningPart => part.type === "reasoning")
 
         expect(value).toBe("continue")
@@ -438,7 +438,7 @@ it.live("session.processor effect tests retry recognized structured json errors"
           tools: {},
         })
 
-        const parts = yield* Effect.promise(() => MessageV2.parts(msg.id))
+        const parts = yield* MessageV2.partsEffect(msg.id)
 
         expect(value).toBe("continue")
         expect(yield* llm.calls).toBe(2)
@@ -596,7 +596,7 @@ it.live("session.processor effect tests mark pending tools as aborted on cleanup
         if (Exit.isFailure(exit) && Cause.hasInterruptsOnly(exit.cause)) {
           yield* handle.abort()
         }
-        const parts = yield* Effect.promise(() => MessageV2.parts(msg.id))
+        const parts = yield* MessageV2.partsEffect(msg.id)
         const call = parts.find((part): part is MessageV2.ToolPart => part.type === "tool")
 
         expect(Exit.isFailure(exit)).toBe(true)
@@ -669,7 +669,7 @@ it.live("session.processor effect tests record aborted errors and idle state", (
           yield* handle.abort()
         }
         yield* Effect.promise(() => seen.promise)
-        const stored = yield* Effect.promise(() => MessageV2.get({ sessionID: chat.id, messageID: msg.id }))
+        const stored = yield* MessageV2.getEffect({ sessionID: chat.id, messageID: msg.id })
         const state = yield* sts.get(chat.id)
         off()
 
@@ -731,7 +731,7 @@ it.live("session.processor effect tests mark interruptions aborted without manua
         yield* Fiber.interrupt(run)
 
         const exit = yield* Fiber.await(run)
-        const stored = yield* Effect.promise(() => MessageV2.get({ sessionID: chat.id, messageID: msg.id }))
+        const stored = yield* MessageV2.getEffect({ sessionID: chat.id, messageID: msg.id })
         const state = yield* sts.get(chat.id)
 
         expect(Exit.isFailure(exit)).toBe(true)

packages/opencode/test/session/prompt-effect.test.ts

@@ -469,7 +469,7 @@ it.live("failed subtask preserves metadata on error tool state", () =>
       expect(result.info.role).toBe("assistant")
       expect(yield* llm.calls).toBe(2)
 
-      const msgs = yield* Effect.promise(() => MessageV2.filterCompacted(MessageV2.stream(chat.id)))
+      const msgs = yield* MessageV2.filterCompactedEffect(chat.id)
       const taskMsg = msgs.find((item) => item.info.role === "assistant" && item.info.agent === "general")
       expect(taskMsg?.info.role).toBe("assistant")
       if (!taskMsg || taskMsg.info.role !== "assistant") return
@@ -628,7 +628,7 @@ it.live(
           const exit = yield* Fiber.await(fiber)
           expect(Exit.isSuccess(exit)).toBe(true)
 
-          const msgs = yield* Effect.promise(() => MessageV2.filterCompacted(MessageV2.stream(chat.id)))
+          const msgs = yield* MessageV2.filterCompactedEffect(chat.id)
           const taskMsg = msgs.find((item) => item.info.role === "assistant" && item.info.agent === "general")
           expect(taskMsg?.info.role).toBe("assistant")
           if (!taskMsg || taskMsg.info.role !== "assistant") return