acp: slash commands, agents, permissions, @ references, code cleanup (#3403)

Co-authored-by: yetone <[email protected]>

9 files changed, 639 insertions, 517 deletions

diff --git a/packages/opencode/src/acp/agent.ts b/packages/opencode/src/acp/agent.ts
index 4f2f6dc46..03bc4d5dd 100644
--- a/packages/opencode/src/acp/agent.ts
+++ b/packages/opencode/src/acp/agent.ts
@@ -1,204 +1,587 @@
 import type {
-  Agent,
+  Agent as ACPAgent,
   AgentSideConnection,
   AuthenticateRequest,
-  AuthenticateResponse,
   CancelNotification,
   InitializeRequest,
-  InitializeResponse,
   LoadSessionRequest,
-  LoadSessionResponse,
   NewSessionRequest,
-  NewSessionResponse,
+  PermissionOption,
   PromptRequest,
-  PromptResponse,
   SetSessionModelRequest,
-  SetSessionModelResponse,
+  SetSessionModeRequest,
+  SetSessionModeResponse,
 } from "@agentclientprotocol/sdk"
 import { Log } from "../util/log"
 import { ACPSessionManager } from "./session"
 import type { ACPConfig } from "./types"
 import { Provider } from "../provider/provider"
 import { SessionPrompt } from "../session/prompt"
-import { Identifier } from "../id/id"
+import { Installation } from "@/installation"
+import { SessionLock } from "@/session/lock"
+import { Bus } from "@/bus"
+import { MessageV2 } from "@/session/message-v2"
+import { Storage } from "@/storage/storage"
+import { Command } from "@/command"
+import { Agent as Agents } from "@/agent/agent"
+import { Permission } from "@/permission"
 
-export class OpenCodeAgent implements Agent {
-  private log = Log.create({ service: "acp-agent" })
-  private sessionManager = new ACPSessionManager()
-  private connection: AgentSideConnection
-  private config: ACPConfig
+export namespace ACP {
+  const log = Log.create({ service: "acp-agent" })
 
-  constructor(connection: AgentSideConnection, config: ACPConfig = {}) {
-    this.connection = connection
-    this.config = config
-  }
+  // TODO: mcp servers?
+
+  type ToolKind =
+    | "read"
+    | "edit"
+    | "delete"
+    | "move"
+    | "search"
+    | "execute"
+    | "think"
+    | "fetch"
+    | "switch_mode"
+    | "other"
+
+  export class Agent implements ACPAgent {
+    private sessionManager = new ACPSessionManager()
+    private connection: AgentSideConnection
+    private config: ACPConfig
 
-  async initialize(params: InitializeRequest): Promise<InitializeResponse> {
-    this.log.info("initialize", { protocolVersion: params.protocolVersion })
-
-    return {
-      protocolVersion: 1,
-      agentCapabilities: {
-        loadSession: false,
-      },
-      _meta: {
-        opencode: {
-          version: await import("../installation").then((m) => m.Installation.VERSION),
+    constructor(connection: AgentSideConnection, config: ACPConfig = {}) {
+      this.connection = connection
+      this.config = config
+      this.setupEventSubscriptions()
+    }
+
+    private setupEventSubscriptions() {
+      const options: PermissionOption[] = [
+        { optionId: "once", kind: "allow_once", name: "Allow once" },
+        { optionId: "always", kind: "allow_always", name: "Always allow" },
+        { optionId: "reject", kind: "reject_once", name: "Reject" },
+      ]
+      Bus.subscribe(Permission.Event.Updated, async (event) => {
+        const acpSession = this.sessionManager.get(event.properties.sessionID)
+        if (!acpSession) return
+        try {
+          const permission = event.properties
+          const res = await this.connection
+            .requestPermission({
+              sessionId: acpSession.id,
+              toolCall: {
+                toolCallId: permission.callID ?? permission.id,
+                status: "pending",
+                title: permission.title,
+                rawInput: permission.metadata,
+                kind: toToolKind(permission.type),
+                locations: toLocations(permission.type, permission.metadata),
+              },
+              options,
+            })
+            .catch((error) => {
+              log.error("failed to request permission from ACP", {
+                error,
+                permissionID: permission.id,
+                sessionID: permission.sessionID,
+              })
+              Permission.respond({
+                sessionID: permission.sessionID,
+                permissionID: permission.id,
+                response: "reject",
+              })
+              return
+            })
+          if (!res) return
+          if (res.outcome.outcome !== "selected") {
+            Permission.respond({ sessionID: permission.sessionID, permissionID: permission.id, response: "reject" })
+            return
+          }
+          Permission.respond({
+            sessionID: permission.sessionID,
+            permissionID: permission.id,
+            response: res.outcome.optionId as "once" | "always" | "reject",
+          })
+        } catch (err) {
+          if (!(err instanceof Permission.RejectedError)) {
+            log.error("unexpected error when handling permission", { error: err })
+            throw err
+          }
+        }
+      })
+
+      Bus.subscribe(MessageV2.Event.PartUpdated, async (event) => {
+        const props = event.properties
+        const { part } = props
+        const acpSession = this.sessionManager.get(part.sessionID)
+        if (!acpSession) return
+
+        const message = await Storage.read<MessageV2.Info>(["message", part.sessionID, part.messageID]).catch(
+          () => undefined,
+        )
+        if (!message || message.role !== "assistant") return
+
+        if (part.type === "tool") {
+          switch (part.state.status) {
+            case "pending":
+              await this.connection
+                .sessionUpdate({
+                  sessionId: acpSession.id,
+                  update: {
+                    sessionUpdate: "tool_call",
+                    toolCallId: part.callID,
+                    title: part.tool,
+                    kind: toToolKind(part.tool),
+                    status: "pending",
+                    locations: [],
+                    rawInput: {},
+                  },
+                })
+                .catch((err) => {
+                  log.error("failed to send tool pending to ACP", { error: err })
+                })
+              break
+            case "running":
+              await this.connection
+                .sessionUpdate({
+                  sessionId: acpSession.id,
+                  update: {
+                    sessionUpdate: "tool_call_update",
+                    toolCallId: part.callID,
+                    status: "in_progress",
+                    locations: toLocations(part.tool, part.state.input),
+                    rawInput: part.state.input,
+                  },
+                })
+                .catch((err) => {
+                  log.error("failed to send tool in_progress to ACP", { error: err })
+                })
+              break
+            case "completed":
+              await this.connection
+                .sessionUpdate({
+                  sessionId: acpSession.id,
+                  update: {
+                    sessionUpdate: "tool_call_update",
+                    toolCallId: part.callID,
+                    status: "completed",
+                    content: [
+                      {
+                        type: "content",
+                        content: {
+                          type: "text",
+                          text: part.state.output,
+                        },
+                      },
+                    ],
+                    title: part.state.title,
+                    rawOutput: {
+                      output: part.state.output,
+                      metadata: part.state.metadata,
+                    },
+                  },
+                })
+                .catch((err) => {
+                  log.error("failed to send tool completed to ACP", { error: err })
+                })
+              break
+            case "error":
+              await this.connection
+                .sessionUpdate({
+                  sessionId: acpSession.id,
+                  update: {
+                    sessionUpdate: "tool_call_update",
+                    toolCallId: part.callID,
+                    status: "failed",
+                    content: [
+                      {
+                        type: "content",
+                        content: {
+                          type: "text",
+                          text: part.state.error,
+                        },
+                      },
+                    ],
+                    rawOutput: {
+                      error: part.state.error,
+                    },
+                  },
+                })
+                .catch((err) => {
+                  log.error("failed to send tool error to ACP", { error: err })
+                })
+              break
+          }
+        } else if (part.type === "text") {
+          const delta = props.delta
+          if (delta && part.synthetic !== true) {
+            await this.connection
+              .sessionUpdate({
+                sessionId: acpSession.id,
+                update: {
+                  sessionUpdate: "agent_message_chunk",
+                  content: {
+                    type: "text",
+                    text: delta,
+                  },
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send text to ACP", { error: err })
+              })
+          }
+        } else if (part.type === "reasoning") {
+          const delta = props.delta
+          if (delta) {
+            await this.connection
+              .sessionUpdate({
+                sessionId: acpSession.id,
+                update: {
+                  sessionUpdate: "agent_thought_chunk",
+                  content: {
+                    type: "text",
+                    text: delta,
+                  },
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send reasoning to ACP", { error: err })
+              })
+          }
+        }
+      })
+    }
+
+    async initialize(params: InitializeRequest) {
+      log.info("initialize", { protocolVersion: params.protocolVersion })
+
+      return {
+        protocolVersion: 1,
+        agentCapabilities: {
+          loadSession: true,
+          // TODO: map acp mcp
+          // mcpCapabilities: {
+          //   http: true,
+          //   sse: true,
+          // },
         },
-      },
+        authMethods: [
+          {
+            description: "Run `opencode auth login` in the terminal",
+            name: "Login with opencode",
+            id: "opencode-login",
+          },
+        ],
+        _meta: {
+          opencode: {
+            version: Installation.VERSION,
+          },
+        },
+      }
     }
-  }
 
-  async authenticate(params: AuthenticateRequest): Promise<void | AuthenticateResponse> {
-    this.log.info("authenticate", { methodId: params.methodId })
-    throw new Error("Authentication not yet implemented")
-  }
+    async authenticate(_params: AuthenticateRequest) {
+      throw new Error("Authentication not implemented")
+    }
 
-  async newSession(params: NewSessionRequest): Promise<NewSessionResponse> {
-    this.log.info("newSession", { cwd: params.cwd, mcpServers: params.mcpServers.length })
+    async newSession(params: NewSessionRequest) {
+      const model = await defaultModel(this.config)
+      const session = await this.sessionManager.create(params.cwd, params.mcpServers, model)
 
-    const model = await this.defaultModel()
-    const session = await this.sessionManager.create(params.cwd, params.mcpServers, model)
-    const availableModels = await this.availableModels()
+      const load = await this.loadSession({
+        cwd: params.cwd,
+        mcpServers: params.mcpServers,
+        sessionId: session.id,
+      })
 
-    return {
-      sessionId: session.id,
-      models: {
-        currentModelId: `${model.providerID}/${model.modelID}`,
-        availableModels,
-      },
-      _meta: {},
+      return {
+        sessionId: session.id,
+        models: load.models,
+        modes: load.modes,
+        _meta: {},
+      }
     }
-  }
 
-  async loadSession(params: LoadSessionRequest): Promise<LoadSessionResponse> {
-    this.log.info("loadSession", { sessionId: params.sessionId, cwd: params.cwd })
+    async loadSession(params: LoadSessionRequest) {
+      const model = await defaultModel(this.config)
+      const sessionId = params.sessionId
+
+      const providers = await Provider.list()
+      const entries = Object.entries(providers).sort((a, b) => {
+        const nameA = a[1].info.name.toLowerCase()
+        const nameB = b[1].info.name.toLowerCase()
+        if (nameA < nameB) return -1
+        if (nameA > nameB) return 1
+        return 0
+      })
+      const availableModels = entries.flatMap(([providerID, provider]) => {
+        const models = Provider.sort(Object.values(provider.info.models))
+        return models.map((model) => ({
+          modelId: `${providerID}/${model.id}`,
+          name: `${provider.info.name}/${model.name}`,
+        }))
+      })
+
+      const availableCommands = (await Command.list()).map((command) => ({
+        name: command.name,
+        description: command.description ?? "",
+      }))
+
+      setTimeout(() => {
+        this.connection.sessionUpdate({
+          sessionId,
+          update: {
+            sessionUpdate: "available_commands_update",
+            availableCommands,
+          },
+        })
+      }, 0)
 
-    const defaultModel = await this.defaultModel()
-    const session = await this.sessionManager.load(params.sessionId, params.cwd, params.mcpServers, defaultModel)
-    const availableModels = await this.availableModels()
+      const availableModes = (await Agents.list())
+        .filter((agent) => agent.mode !== "subagent")
+        .map((agent) => ({
+          id: agent.name,
+          name: agent.name,
+          description: agent.description,
+        }))
 
-    return {
-      models: {
-        currentModelId: `${session.model.providerID}/${session.model.modelID}`,
-        availableModels,
-      },
-      _meta: {},
+      const currentModeId = availableModes.find((m) => m.name === "build")?.id ?? availableModes[0].id
+
+      return {
+        sessionId,
+        models: {
+          currentModelId: `${model.providerID}/${model.modelID}`,
+          availableModels,
+        },
+        modes: {
+          availableModes,
+          currentModeId,
+        },
+        _meta: {},
+      }
     }
-  }
 
-  async setSessionModel(params: SetSessionModelRequest): Promise<SetSessionModelResponse> {
-    this.log.info("setSessionModel", { sessionId: params.sessionId, modelId: params.modelId })
+    async setSessionModel(params: SetSessionModelRequest) {
+      const session = this.sessionManager.get(params.sessionId)
+      if (!session) {
+        throw new Error(`Session not found: ${params.sessionId}`)
+      }
+
+      const parsed = Provider.parseModel(params.modelId)
+      const model = await Provider.getModel(parsed.providerID, parsed.modelID)
+
+      this.sessionManager.setModel(session.id, {
+        providerID: model.providerID,
+        modelID: model.modelID,
+      })
 
-    const session = this.sessionManager.get(params.sessionId)
-    if (!session) {
-      throw new Error(`Session not found: ${params.sessionId}`)
+      return {
+        _meta: {},
+      }
     }
 
-    const parsed = Provider.parseModel(params.modelId)
-    const model = await Provider.getModel(parsed.providerID, parsed.modelID)
+    async setSessionMode(params: SetSessionModeRequest): Promise<SetSessionModeResponse | void> {
+      const session = this.sessionManager.get(params.sessionId)
+      if (!session) {
+        throw new Error(`Session not found: ${params.sessionId}`)
+      }
+      await Agents.get(params.modeId).then((agent) => {
+        if (!agent) throw new Error(`Agent not found: ${params.modeId}`)
+      })
+      this.sessionManager.setMode(params.sessionId, params.modeId)
+    }
 
-    this.sessionManager.setModel(session.id, {
-      providerID: model.providerID,
-      modelID: model.modelID,
-    })
+    async prompt(params: PromptRequest) {
+      const sessionID = params.sessionId
+      const acpSession = this.sessionManager.get(sessionID)
+      if (!acpSession) {
+        throw new Error(`Session not found: ${sessionID}`)
+      }
+
+      const current = acpSession.model
+      const model = current ?? (await defaultModel(this.config))
+      if (!current) {
+        this.sessionManager.setModel(acpSession.id, model)
+      }
+      const agent = acpSession.modeId ?? "build"
+
+      const parts: SessionPrompt.PromptInput["parts"] = []
+      for (const part of params.prompt) {
+        switch (part.type) {
+          case "text":
+            parts.push({
+              type: "text" as const,
+              text: part.text,
+            })
+            break
+          case "image":
+            if (part.data) {
+              parts.push({
+                type: "file",
+                url: `data:${part.mimeType};base64,${part.data}`,
+                mime: part.mimeType,
+              })
+            } else if (part.uri && part.uri.startsWith("http:")) {
+              parts.push({
+                type: "file",
+                url: part.uri,
+                mime: part.mimeType,
+              })
+            }
+            break
+
+          case "resource_link":
+            const parsed = parseUri(part.uri)
+            parts.push(parsed)
+
+            break
+
+          case "resource":
+            const resource = part.resource
+            if ("text" in resource) {
+              parts.push({
+                type: "text",
+                text: resource.text,
+              })
+            }
+            break
+
+          default:
+            break
+        }
+      }
 
-    return {
-      _meta: {},
+      log.info("parts", { parts })
+
+      const cmd = await (async () => {
+        const text = parts.filter((part) => part.type === "text").join("")
+        const match = text.match(/^\/(\w+)\s*(.*)$/)
+        if (!match) return
+
+        const [c, args] = match.slice(1)
+        const command = await Command.get(c)
+        if (!command) return
+        return { command, args }
+      })()
+
+      if (cmd) {
+        await SessionPrompt.command({
+          sessionID,
+          command: cmd.command.name,
+          arguments: cmd.args,
+          agent,
+        })
+      } else {
+        await SessionPrompt.prompt({
+          sessionID,
+          model: {
+            providerID: model.providerID,
+            modelID: model.modelID,
+          },
+          parts,
+          agent,
+        })
+      }
+
+      return {
+        stopReason: "end_turn" as const,
+        _meta: {},
+      }
     }
-  }
 
-  private async defaultModel() {
-    const configured = this.config.defaultModel
-    if (configured) return configured
-    return Provider.defaultModel()
+    async cancel(params: CancelNotification) {
+      SessionLock.abort(params.sessionId)
+    }
   }
 
-  private async availableModels() {
-    const providers = await Provider.list()
-    const entries = Object.entries(providers).sort((a, b) => {
-      const nameA = a[1].info.name.toLowerCase()
-      const nameB = b[1].info.name.toLowerCase()
-      if (nameA < nameB) return -1
-      if (nameA > nameB) return 1
-      return 0
-    })
-    return entries.flatMap(([providerID, provider]) => {
-      const models = Provider.sort(Object.values(provider.info.models))
-      return models.map((model) => ({
-        modelId: `${providerID}/${model.id}`,
-        name: `${provider.info.name}/${model.name}`,
-      }))
-    })
-  }
+  function toToolKind(toolName: string): ToolKind {
+    const tool = toolName.toLocaleLowerCase()
+    switch (tool) {
+      case "bash":
+        return "execute"
+      case "webfetch":
+        return "fetch"
+
+      case "edit":
+      case "patch":
+      case "write":
+        return "edit"
+
+      case "grep":
+      case "glob":
+      case "context7_resolve_library_id":
+      case "context7_get_library_docs":
+        return "search"
 
-  async prompt(params: PromptRequest): Promise<PromptResponse> {
-    this.log.info("prompt", {
-      sessionId: params.sessionId,
-      promptLength: params.prompt.length,
-    })
+      case "list":
+      case "read":
+        return "read"
 
-    const acpSession = this.sessionManager.get(params.sessionId)
-    if (!acpSession) {
-      throw new Error(`Session not found: ${params.sessionId}`)
+      default:
+        return "other"
     }
+  }
 
-    const current = acpSession.model
-    const model = current ?? (await this.defaultModel())
-    if (!current) {
-      this.sessionManager.setModel(acpSession.id, model)
+  function toLocations(toolName: string, input: Record<string, any>): { path: string }[] {
+    const tool = toolName.toLocaleLowerCase()
+    switch (tool) {
+      case "read":
+      case "edit":
+      case "write":
+        return input["filePath"] ? [{ path: input["filePath"] }] : []
+      case "glob":
+      case "grep":
+        return input["path"] ? [{ path: input["path"] }] : []
+      case "bash":
+        return []
+      case "list":
+        return input["path"] ? [{ path: input["path"] }] : []
+      default:
+        return []
     }
+  }
+
+  async function defaultModel(config: ACPConfig) {
+    const configured = config.defaultModel
+    if (configured) return configured
+    return Provider.defaultModel()
+  }
 
-    const parts = params.prompt.map((content) => {
-      if (content.type === "text") {
+  function parseUri(
+    uri: string,
+  ): { type: "file"; url: string; filename: string; mime: string } | { type: "text"; text: string } {
+    try {
+      if (uri.startsWith("file://")) {
+        const path = uri.slice(7)
+        const name = path.split("/").pop() || path
         return {
-          type: "text" as const,
-          text: content.text,
+          type: "file",
+          url: uri,
+          filename: name,
+          mime: "text/plain",
         }
       }
-      if (content.type === "resource") {
-        const resource = content.resource
-        let text = ""
-        if ("text" in resource && typeof resource.text === "string") {
-          text = resource.text
-        }
-        return {
-          type: "text" as const,
-          text,
+      if (uri.startsWith("zed://")) {
+        const url = new URL(uri)
+        const path = url.searchParams.get("path")
+        if (path) {
+          const name = path.split("/").pop() || path
+          return {
+            type: "file",
+            url: `file://${path}`,
+            filename: name,
+            mime: "text/plain",
+          }
         }
       }
       return {
-        type: "text" as const,
-        text: JSON.stringify(content),
+        type: "text",
+        text: uri,
+      }
+    } catch {
+      return {
+        type: "text",
+        text: uri,
       }
-    })
-
-    await SessionPrompt.prompt({
-      sessionID: acpSession.openCodeSessionId,
-      messageID: Identifier.ascending("message"),
-      model: {
-        providerID: model.providerID,
-        modelID: model.modelID,
-      },
-      parts,
-      acpConnection: {
-        connection: this.connection,
-        sessionId: params.sessionId,
-      },
-    })
-
-    this.log.debug("prompt response completed")
-
-    // Streaming notifications are now handled during prompt execution
-    // No need to send final text chunk here
-
-    return {
-      stopReason: "end_turn",
-      _meta: {},
     }
   }
-
-  async cancel(params: CancelNotification): Promise<void> {
-    this.log.info("cancel", { sessionId: params.sessionId })
-  }
 }
diff --git a/packages/opencode/src/acp/client.ts b/packages/opencode/src/acp/client.ts
deleted file mode 100644
index 24119eabe..000000000
--- a/packages/opencode/src/acp/client.ts
+++ /dev/null
@@ -1,85 +0,0 @@
-import type {
-  Client,
-  CreateTerminalRequest,
-  CreateTerminalResponse,
-  KillTerminalCommandRequest,
-  KillTerminalResponse,
-  ReadTextFileRequest,
-  ReadTextFileResponse,
-  ReleaseTerminalRequest,
-  ReleaseTerminalResponse,
-  RequestPermissionRequest,
-  RequestPermissionResponse,
-  SessionNotification,
-  TerminalOutputRequest,
-  TerminalOutputResponse,
-  WaitForTerminalExitRequest,
-  WaitForTerminalExitResponse,
-  WriteTextFileRequest,
-  WriteTextFileResponse,
-} from "@agentclientprotocol/sdk"
-import { Log } from "../util/log"
-
-export class ACPClient implements Client {
-  private log = Log.create({ service: "acp-client" })
-
-  async requestPermission(params: RequestPermissionRequest): Promise<RequestPermissionResponse> {
-    this.log.debug("requestPermission", params)
-    const firstOption = params.options[0]
-    if (!firstOption) {
-      return { outcome: { outcome: "cancelled" } }
-    }
-    return {
-      outcome: {
-        outcome: "selected",
-        optionId: firstOption.optionId,
-      },
-    }
-  }
-
-  async sessionUpdate(params: SessionNotification): Promise<void> {
-    this.log.debug("sessionUpdate", { sessionId: params.sessionId })
-  }
-
-  async writeTextFile(params: WriteTextFileRequest): Promise<WriteTextFileResponse> {
-    this.log.debug("writeTextFile", { path: params.path })
-    await Bun.write(params.path, params.content)
-    return { _meta: {} }
-  }
-
-  async readTextFile(params: ReadTextFileRequest): Promise<ReadTextFileResponse> {
-    this.log.debug("readTextFile", { path: params.path })
-    const file = Bun.file(params.path)
-    const exists = await file.exists()
-    if (!exists) {
-      throw new Error(`File not found: ${params.path}`)
-    }
-    const content = await file.text()
-    return { content, _meta: {} }
-  }
-
-  async createTerminal(params: CreateTerminalRequest): Promise<CreateTerminalResponse> {
-    this.log.debug("createTerminal", params)
-    throw new Error("Terminal support not yet implemented")
-  }
-
-  async terminalOutput(params: TerminalOutputRequest): Promise<TerminalOutputResponse> {
-    this.log.debug("terminalOutput", params)
-    throw new Error("Terminal support not yet implemented")
-  }
-
-  async releaseTerminal(params: ReleaseTerminalRequest): Promise<void | ReleaseTerminalResponse> {
-    this.log.debug("releaseTerminal", params)
-    throw new Error("Terminal support not yet implemented")
-  }
-
-  async waitForTerminalExit(params: WaitForTerminalExitRequest): Promise<WaitForTerminalExitResponse> {
-    this.log.debug("waitForTerminalExit", params)
-    throw new Error("Terminal support not yet implemented")
-  }
-
-  async killTerminal(params: KillTerminalCommandRequest): Promise<void | KillTerminalResponse> {
-    this.log.debug("killTerminal", params)
-    throw new Error("Terminal support not yet implemented")
-  }
-}
diff --git a/packages/opencode/src/acp/server.ts b/packages/opencode/src/acp/server.ts
deleted file mode 100644
index 0e5306dcd..000000000
--- a/packages/opencode/src/acp/server.ts
+++ /dev/null
@@ -1,53 +0,0 @@
-import { AgentSideConnection, ndJsonStream } from "@agentclientprotocol/sdk"
-import { Log } from "../util/log"
-import { Instance } from "../project/instance"
-import { OpenCodeAgent } from "./agent"
-
-export namespace ACPServer {
-  const log = Log.create({ service: "acp-server" })
-
-  export async function start() {
-    await Instance.provide({
-      directory: process.cwd(),
-      fn: async () => {
-        log.info("starting ACP server", { cwd: process.cwd() })
-
-        const stdout = new WritableStream({
-          write(chunk) {
-            process.stdout.write(chunk)
-          },
-        })
-
-        const stdin = new ReadableStream({
-          start(controller) {
-            process.stdin.on("data", (chunk) => {
-              controller.enqueue(new Uint8Array(chunk))
-            })
-            process.stdin.on("end", () => {
-              controller.close()
-            })
-          },
-        })
-
-        const stream = ndJsonStream(stdout, stdin)
-
-        new AgentSideConnection((conn) => {
-          return new OpenCodeAgent(conn)
-        }, stream)
-
-        await new Promise<void>((resolve) => {
-          process.on("SIGTERM", () => {
-            log.info("received SIGTERM")
-            resolve()
-          })
-          process.on("SIGINT", () => {
-            log.info("received SIGINT")
-            resolve()
-          })
-        })
-
-        log.info("ACP server stopped")
-      },
-    })
-  }
-}
diff --git a/packages/opencode/src/acp/session.ts b/packages/opencode/src/acp/session.ts
index 3a7972590..652e8cfdd 100644
--- a/packages/opencode/src/acp/session.ts
+++ b/packages/opencode/src/acp/session.ts
@@ -7,20 +7,15 @@ import type { ACPSessionState } from "./types"
 export class ACPSessionManager {
   private sessions = new Map<string, ACPSessionState>()
 
-  async create(
-    cwd: string,
-    mcpServers: McpServer[],
-    model?: ACPSessionState["model"],
-  ): Promise<ACPSessionState> {
-    const sessionId = `acp_${Identifier.ascending("session")}`
-    const openCodeSession = await Session.create({ title: `ACP Session ${sessionId}` })
+  async create(cwd: string, mcpServers: McpServer[], model?: ACPSessionState["model"]): Promise<ACPSessionState> {
+    const session = await Session.create({ title: `ACP Session ${crypto.randomUUID()}` })
+    const sessionId = session.id
     const resolvedModel = model ?? (await Provider.defaultModel())
 
     const state: ACPSessionState = {
       id: sessionId,
       cwd,
       mcpServers,
-      openCodeSessionId: openCodeSession.id,
       createdAt: new Date(),
       model: resolvedModel,
     }
@@ -29,54 +24,22 @@ export class ACPSessionManager {
     return state
   }
 
-  get(sessionId: string): ACPSessionState | undefined {
+  get(sessionId: string) {
     return this.sessions.get(sessionId)
   }
 
-  async remove(sessionId: string): Promise<void> {
+  async remove(sessionId: string) {
     const state = this.sessions.get(sessionId)
     if (!state) return
 
-    await Session.remove(state.openCodeSessionId).catch(() => {})
+    await Session.remove(sessionId).catch(() => {})
     this.sessions.delete(sessionId)
   }
 
-  has(sessionId: string): boolean {
+  has(sessionId: string) {
     return this.sessions.has(sessionId)
   }
 
-  async load(
-    sessionId: string,
-    cwd: string,
-    mcpServers: McpServer[],
-    model?: ACPSessionState["model"],
-  ): Promise<ACPSessionState> {
-    const existing = this.sessions.get(sessionId)
-    if (existing) {
-      if (!existing.model) {
-        const resolved = model ?? (await Provider.defaultModel())
-        existing.model = resolved
-        this.sessions.set(sessionId, existing)
-      }
-      return existing
-    }
-
-    const openCodeSession = await Session.create({ title: `ACP Session ${sessionId} (loaded)` })
-    const resolvedModel = model ?? (await Provider.defaultModel())
-
-    const state: ACPSessionState = {
-      id: sessionId,
-      cwd,
-      mcpServers,
-      openCodeSessionId: openCodeSession.id,
-      createdAt: new Date(),
-      model: resolvedModel,
-    }
-
-    this.sessions.set(sessionId, state)
-    return state
-  }
-
   getModel(sessionId: string) {
     const session = this.sessions.get(sessionId)
     if (!session) return
@@ -90,4 +53,12 @@ export class ACPSessionManager {
     this.sessions.set(sessionId, session)
     return session
   }
+
+  setMode(sessionId: string, modeId: string) {
+    const session = this.sessions.get(sessionId)
+    if (!session) return
+    session.modeId = modeId
+    this.sessions.set(sessionId, session)
+    return session
+  }
 }
diff --git a/packages/opencode/src/acp/types.ts b/packages/opencode/src/acp/types.ts
index 1bffa0197..56308cb76 100644
--- a/packages/opencode/src/acp/types.ts
+++ b/packages/opencode/src/acp/types.ts
@@ -4,12 +4,12 @@ export interface ACPSessionState {
   id: string
   cwd: string
   mcpServers: McpServer[]
-  openCodeSessionId: string
   createdAt: Date
   model: {
     providerID: string
     modelID: string
   }
+  modeId?: string
 }
 
 export interface ACPConfig {
diff --git a/packages/opencode/src/cli/cmd/acp.ts b/packages/opencode/src/cli/cmd/acp.ts
index f415cd6ad..6628137f4 100644
--- a/packages/opencode/src/cli/cmd/acp.ts
+++ b/packages/opencode/src/cli/cmd/acp.ts
@@ -1,5 +1,17 @@
-import { ACPServer } from "../../acp/server"
+import { Log } from "@/util/log"
+import { bootstrap } from "../bootstrap"
 import { cmd } from "./cmd"
+import { AgentSideConnection, ndJsonStream } from "@agentclientprotocol/sdk"
+import { ACP } from "@/acp/agent"
+
+const log = Log.create({ service: "acp-command" })
+
+process.on("unhandledRejection", (reason, promise) => {
+  log.error("Unhandled rejection", {
+    promise,
+    reason,
+  })
+})
 
 export const AcpCommand = cmd({
   command: "acp",
@@ -13,6 +25,38 @@ export const AcpCommand = cmd({
   },
   handler: async (opts) => {
     if (opts.cwd) process.chdir(opts["cwd"])
-    await ACPServer.start()
+    await bootstrap(process.cwd(), async () => {
+      const input = new WritableStream<Uint8Array>({
+        write(chunk) {
+          return new Promise<void>((resolve, reject) => {
+            process.stdout.write(Buffer.from(chunk), (err) => {
+              if (err) {
+                reject(err)
+              } else {
+                resolve()
+              }
+            })
+          })
+        },
+      })
+      const output = new ReadableStream<Uint8Array>({
+        start(controller) {
+          process.stdin.on("data", (chunk: Buffer) => {
+            controller.enqueue(new Uint8Array(chunk))
+          })
+          process.stdin.on("end", () => controller.close())
+          process.stdin.on("error", (err) => controller.error(err))
+        },
+      })
+
+      const stream = ndJsonStream(input, output)
+
+      new AgentSideConnection((conn) => {
+        return new ACP.Agent(conn)
+      }, stream)
+
+      log.info("setup connection")
+    })
+    process.stdin.resume()
   },
 })
diff --git a/packages/opencode/src/session/index.ts b/packages/opencode/src/session/index.ts
index 64f64082e..640dd55c2 100644
--- a/packages/opencode/src/session/index.ts
+++ b/packages/opencode/src/session/index.ts
@@ -340,10 +340,25 @@ export namespace Session {
     },
   )
 
-  export const updatePart = fn(MessageV2.Part, async (part) => {
+  const UpdatePartInput = z.union([
+    MessageV2.Part,
+    z.object({
+      part: MessageV2.TextPart,
+      delta: z.string(),
+    }),
+    z.object({
+      part: MessageV2.ReasoningPart,
+      delta: z.string(),
+    }),
+  ])
+
+  export const updatePart = fn(UpdatePartInput, async (input) => {
+    const part = "delta" in input ? input.part : input
+    const delta = "delta" in input ? input.delta : undefined
     await Storage.write(["part", part.messageID, part.id], part)
     Bus.publish(MessageV2.Event.PartUpdated, {
       part,
+      delta,
     })
     return part
   })
diff --git a/packages/opencode/src/session/message-v2.ts b/packages/opencode/src/session/message-v2.ts
index b3efefcc9..c37773b74 100644
--- a/packages/opencode/src/session/message-v2.ts
+++ b/packages/opencode/src/session/message-v2.ts
@@ -359,6 +359,7 @@ export namespace MessageV2 {
       "message.part.updated",
       z.object({
         part: Part,
+        delta: z.string().optional(),
       }),
     ),
     PartRemoved: Bus.event(
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index b6ec891bc..6adeb6f7e 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -96,16 +96,6 @@ export namespace SessionPrompt {
     agent: z.string().optional(),
     system: z.string().optional(),
     tools: z.record(z.string(), z.boolean()).optional(),
-    /**
-     * ACP (Agent Client Protocol) connection details for streaming responses.
-     * When provided, enables real-time streaming and tool execution visibility.
-     */
-    acpConnection: z
-      .object({
-        connection: z.any(), // AgentSideConnection - using any to avoid circular deps
-        sessionId: z.string(), // ACP session ID (different from opencode sessionID)
-      })
-      .optional(),
     parts: z.array(
       z.discriminatedUnion("type", [
         MessageV2.TextPart.omit({
@@ -184,7 +174,6 @@ export namespace SessionPrompt {
       agent: agent.name,
       system,
       abort: abort.signal,
-      acpConnection: input.acpConnection,
     })
 
     const tools = await resolveTools({
@@ -196,6 +185,28 @@ export namespace SessionPrompt {
       processor,
     })
 
+    // const permUnsub = (() => {
+    //   const handled = new Set<string>()
+    //   const options = [
+    //     { optionId: "allow_once", kind: "allow_once", name: "Allow once" },
+    //     { optionId: "allow_always", kind: "allow_always", name: "Always allow" },
+    //     { optionId: "reject_once", kind: "reject_once", name: "Reject" },
+    //   ]
+    //   return Bus.subscribe(Permission.Event.Updated, async (event) => {
+    //     const info = event.properties
+    //     if (info.sessionID !== input.sessionID) return
+    //     if (handled.has(info.id)) return
+    //     handled.add(info.id)
+    //     const toolCallId = info.callID ?? info.id
+    //     const metadata = info.metadata ?? {}
+    //     // TODO: emit permission event to bus for ACP to handle
+    //     Permission.respond({ sessionID: info.sessionID, permissionID: info.id, response: "reject" })
+    //   })
+    // })()
+    // await using _permSub = defer(() => {
+    //   permUnsub?.()
+    // })
+
     const params = await Plugin.trigger(
       "chat.params",
       {
@@ -889,60 +900,6 @@ export namespace SessionPrompt {
     return input.messages
   }
 
-  /**
-   * Maps tool names to ACP tool kinds for consistent categorization.
-   * - read: Tools that read data (read, glob, grep, list, webfetch, docs)
-   * - edit: Tools that modify state (edit, write, bash)
-   * - other: All other tools (MCP tools, task, todowrite, etc.)
-   */
-  function determineToolKind(toolName: string): "read" | "edit" | "other" {
-    const readTools = [
-      "read",
-      "glob",
-      "grep",
-      "list",
-      "webfetch",
-      "context7_resolve_library_id",
-      "context7_get_library_docs",
-    ]
-    const editTools = ["edit", "write", "bash"]
-
-    if (readTools.includes(toolName.toLowerCase())) return "read"
-    if (editTools.includes(toolName.toLowerCase())) return "edit"
-    return "other"
-  }
-
-  /**
-   * Extracts file/directory locations from tool inputs for ACP notifications.
-   * Returns array of {path} objects that ACP clients can use for navigation.
-   *
-   * Examples:
-   * - read({filePath: "/foo/bar.ts"}) -> [{path: "/foo/bar.ts"}]
-   * - glob({pattern: "*.ts", path: "/src"}) -> [{path: "/src"}]
-   * - bash({command: "ls"}) -> [] (no file references)
-   */
-  function extractLocations(toolName: string, input: Record<string, any>): { path: string }[] {
-    try {
-      switch (toolName.toLowerCase()) {
-        case "read":
-        case "edit":
-        case "write":
-          return input["filePath"] ? [{ path: input["filePath"] }] : []
-        case "glob":
-        case "grep":
-          return input["path"] ? [{ path: input["path"] }] : []
-        case "bash":
-          return []
-        case "list":
-          return input["path"] ? [{ path: input["path"] }] : []
-        default:
-          return []
-      }
-    } catch {
-      return []
-    }
-  }
-
   export type Processor = Awaited<ReturnType<typeof createProcessor>>
   async function createProcessor(input: {
     sessionID: string
@@ -951,10 +908,6 @@ export namespace SessionPrompt {
     system: string[]
     agent: string
     abort: AbortSignal
-    acpConnection?: {
-      connection: any
-      sessionId: string
-    }
   }) {
     const toolcalls: Record<string, MessageV2.ToolPart> = {}
     let snapshot: string | undefined
@@ -1052,7 +1005,7 @@ export namespace SessionPrompt {
                   const part = reasoningMap[value.id]
                   part.text += value.text
                   if (value.providerMetadata) part.metadata = value.providerMetadata
-                  if (part.text) await Session.updatePart(part)
+                  if (part.text) await Session.updatePart({ part, delta: value.text })
                 }
                 break
 
@@ -1084,26 +1037,6 @@ export namespace SessionPrompt {
                   },
                 })
                 toolcalls[value.id] = part as MessageV2.ToolPart
-
-                // Notify ACP client of pending tool call
-                if (input.acpConnection) {
-                  await input.acpConnection.connection
-                    .sessionUpdate({
-                      sessionId: input.acpConnection.sessionId,
-                      update: {
-                        sessionUpdate: "tool_call",
-                        toolCallId: value.id,
-                        title: value.toolName,
-                        kind: determineToolKind(value.toolName),
-                        status: "pending",
-                        locations: [], // Will be populated when we have input
-                        rawInput: {},
-                      },
-                    })
-                    .catch((err: Error) => {
-                      log.error("failed to send tool pending to ACP", { error: err })
-                    })
-                }
                 break
 
               case "tool-input-delta":
@@ -1128,24 +1061,6 @@ export namespace SessionPrompt {
                     metadata: value.providerMetadata,
                   })
                   toolcalls[value.toolCallId] = part as MessageV2.ToolPart
-
-                  // Notify ACP client that tool is running
-                  if (input.acpConnection) {
-                    await input.acpConnection.connection
-                      .sessionUpdate({
-                        sessionId: input.acpConnection.sessionId,
-                        update: {
-                          sessionUpdate: "tool_call_update",
-                          toolCallId: value.toolCallId,
-                          status: "in_progress",
-                          locations: extractLocations(value.toolName, value.input),
-                          rawInput: value.input,
-                        },
-                      })
-                      .catch((err: Error) => {
-                        log.error("failed to send tool in_progress to ACP", { error: err })
-                      })
-                  }
                 }
                 break
               }
@@ -1168,32 +1083,6 @@ export namespace SessionPrompt {
                     },
                   })
 
-                  // Notify ACP client that tool completed
-                  if (input.acpConnection) {
-                    await input.acpConnection.connection
-                      .sessionUpdate({
-                        sessionId: input.acpConnection.sessionId,
-                        update: {
-                          sessionUpdate: "tool_call_update",
-                          toolCallId: value.toolCallId,
-                          status: "completed",
-                          content: [
-                            {
-                              type: "content",
-                              content: {
-                                type: "text",
-                                text: value.output.output,
-                              },
-                            },
-                          ],
-                          rawOutput: value.output,
-                        },
-                      })
-                      .catch((err: Error) => {
-                        log.error("failed to send tool completed to ACP", { error: err })
-                      })
-                  }
-
                   delete toolcalls[value.toolCallId]
                 }
                 break
@@ -1216,34 +1105,6 @@ export namespace SessionPrompt {
                     },
                   })
 
-                  // Notify ACP client of tool error
-                  if (input.acpConnection) {
-                    await input.acpConnection.connection
-                      .sessionUpdate({
-                        sessionId: input.acpConnection.sessionId,
-                        update: {
-                          sessionUpdate: "tool_call_update",
-                          toolCallId: value.toolCallId,
-                          status: "failed",
-                          content: [
-                            {
-                              type: "content",
-                              content: {
-                                type: "text",
-                                text: `Error: ${(value.error as any).toString()}`,
-                              },
-                            },
-                          ],
-                          rawOutput: {
-                            error: (value.error as any).toString(),
-                          },
-                        },
-                      })
-                      .catch((err: Error) => {
-                        log.error("failed to send tool error to ACP", { error: err })
-                      })
-                  }
-
                   if (value.error instanceof Permission.RejectedError) {
                     blocked = true
                   }
@@ -1322,26 +1183,11 @@ export namespace SessionPrompt {
                 if (currentText) {
                   currentText.text += value.text
                   if (value.providerMetadata) currentText.metadata = value.providerMetadata
-                  if (currentText.text) await Session.updatePart(currentText)
-
-                  // Send streaming chunk to ACP client
-                  if (input.acpConnection && value.text) {
-                    await input.acpConnection.connection
-                      .sessionUpdate({
-                        sessionId: input.acpConnection.sessionId,
-                        update: {
-                          sessionUpdate: "agent_message_chunk",
-                          content: {
-                            type: "text",
-                            text: value.text,
-                          },
-                        },
-                      })
-                      .catch((err: Error) => {
-                        log.error("failed to send text delta to ACP", { error: err })
-                        // Don't fail the whole request if ACP notification fails
-                      })
-                  }
+                  if (currentText.text)
+                    await Session.updatePart({
+                      part: currentText,
+                      delta: value.text,
+                    })
                 }
                 break