refactor: unwrap ACP namespace + self-reexport (#22936)

1 files changed, 1465 insertions, 1465 deletions

diff --git a/packages/opencode/src/acp/agent.ts b/packages/opencode/src/acp/agent.ts
index 5d8c723ea..7180feabc 100644
--- a/packages/opencode/src/acp/agent.ts
+++ b/packages/opencode/src/acp/agent.ts
@@ -57,793 +57,262 @@ type ModelOption = { modelId: string; name: string }
 
 const DEFAULT_VARIANT_VALUE = "default"
 
-export namespace ACP {
-  const log = Log.create({ service: "acp-agent" })
-
-  async function getContextLimit(
-    sdk: OpencodeClient,
-    providerID: ProviderID,
-    modelID: ModelID,
-    directory: string,
-  ): Promise<number | null> {
-    const providers = await sdk.config
-      .providers({ directory })
-      .then((x) => x.data?.providers ?? [])
-      .catch((error) => {
-        log.error("failed to get providers for context limit", { error })
-        return []
-      })
+const log = Log.create({ service: "acp-agent" })
+
+async function getContextLimit(
+  sdk: OpencodeClient,
+  providerID: ProviderID,
+  modelID: ModelID,
+  directory: string,
+): Promise<number | null> {
+  const providers = await sdk.config
+    .providers({ directory })
+    .then((x) => x.data?.providers ?? [])
+    .catch((error) => {
+      log.error("failed to get providers for context limit", { error })
+      return []
+    })
 
-    const provider = providers.find((p) => p.id === providerID)
-    const model = provider?.models[modelID]
-    return model?.limit.context ?? null
-  }
+  const provider = providers.find((p) => p.id === providerID)
+  const model = provider?.models[modelID]
+  return model?.limit.context ?? null
+}
 
-  async function sendUsageUpdate(
-    connection: AgentSideConnection,
-    sdk: OpencodeClient,
-    sessionID: string,
-    directory: string,
-  ): Promise<void> {
-    const messages = await sdk.session
-      .messages({ sessionID, directory }, { throwOnError: true })
-      .then((x) => x.data)
-      .catch((error) => {
-        log.error("failed to fetch messages for usage update", { error })
-        return undefined
-      })
+async function sendUsageUpdate(
+  connection: AgentSideConnection,
+  sdk: OpencodeClient,
+  sessionID: string,
+  directory: string,
+): Promise<void> {
+  const messages = await sdk.session
+    .messages({ sessionID, directory }, { throwOnError: true })
+    .then((x) => x.data)
+    .catch((error) => {
+      log.error("failed to fetch messages for usage update", { error })
+      return undefined
+    })
 
-    if (!messages) return
+  if (!messages) return
 
-    const assistantMessages = messages.filter(
-      (m): m is { info: AssistantMessage; parts: SessionMessageResponse["parts"] } => m.info.role === "assistant",
-    )
+  const assistantMessages = messages.filter(
+    (m): m is { info: AssistantMessage; parts: SessionMessageResponse["parts"] } => m.info.role === "assistant",
+  )
 
-    const lastAssistant = assistantMessages[assistantMessages.length - 1]
-    if (!lastAssistant) return
+  const lastAssistant = assistantMessages[assistantMessages.length - 1]
+  if (!lastAssistant) return
 
-    const msg = lastAssistant.info
-    if (!msg.providerID || !msg.modelID) return
-    const size = await getContextLimit(sdk, ProviderID.make(msg.providerID), ModelID.make(msg.modelID), directory)
+  const msg = lastAssistant.info
+  if (!msg.providerID || !msg.modelID) return
+  const size = await getContextLimit(sdk, ProviderID.make(msg.providerID), ModelID.make(msg.modelID), directory)
 
-    if (!size) {
-      // Cannot calculate usage without known context size
-      return
-    }
+  if (!size) {
+    // Cannot calculate usage without known context size
+    return
+  }
 
-    const used = msg.tokens.input + (msg.tokens.cache?.read ?? 0)
-    const totalCost = assistantMessages.reduce((sum, m) => sum + m.info.cost, 0)
+  const used = msg.tokens.input + (msg.tokens.cache?.read ?? 0)
+  const totalCost = assistantMessages.reduce((sum, m) => sum + m.info.cost, 0)
+
+  await connection
+    .sessionUpdate({
+      sessionId: sessionID,
+      update: {
+        sessionUpdate: "usage_update",
+        used,
+        size,
+        cost: { amount: totalCost, currency: "USD" },
+      },
+    })
+    .catch((error) => {
+      log.error("failed to send usage update", { error })
+    })
+}
 
-    await connection
-      .sessionUpdate({
-        sessionId: sessionID,
-        update: {
-          sessionUpdate: "usage_update",
-          used,
-          size,
-          cost: { amount: totalCost, currency: "USD" },
-        },
-      })
-      .catch((error) => {
-        log.error("failed to send usage update", { error })
-      })
+export async function init({ sdk: _sdk }: { sdk: OpencodeClient }) {
+  return {
+    create: (connection: AgentSideConnection, fullConfig: ACPConfig) => {
+      return new Agent(connection, fullConfig)
+    },
   }
+}
 
-  export async function init({ sdk: _sdk }: { sdk: OpencodeClient }) {
-    return {
-      create: (connection: AgentSideConnection, fullConfig: ACPConfig) => {
-        return new Agent(connection, fullConfig)
-      },
-    }
+export class Agent implements ACPAgent {
+  private connection: AgentSideConnection
+  private config: ACPConfig
+  private sdk: OpencodeClient
+  private sessionManager: ACPSessionManager
+  private eventAbort = new AbortController()
+  private eventStarted = false
+  private bashSnapshots = new Map<string, string>()
+  private toolStarts = new Set<string>()
+  private permissionQueues = new Map<string, Promise<void>>()
+  private permissionOptions: PermissionOption[] = [
+    { optionId: "once", kind: "allow_once", name: "Allow once" },
+    { optionId: "always", kind: "allow_always", name: "Always allow" },
+    { optionId: "reject", kind: "reject_once", name: "Reject" },
+  ]
+
+  constructor(connection: AgentSideConnection, config: ACPConfig) {
+    this.connection = connection
+    this.config = config
+    this.sdk = config.sdk
+    this.sessionManager = new ACPSessionManager(this.sdk)
+    this.startEventSubscription()
   }
 
-  export class Agent implements ACPAgent {
-    private connection: AgentSideConnection
-    private config: ACPConfig
-    private sdk: OpencodeClient
-    private sessionManager: ACPSessionManager
-    private eventAbort = new AbortController()
-    private eventStarted = false
-    private bashSnapshots = new Map<string, string>()
-    private toolStarts = new Set<string>()
-    private permissionQueues = new Map<string, Promise<void>>()
-    private permissionOptions: PermissionOption[] = [
-      { optionId: "once", kind: "allow_once", name: "Allow once" },
-      { optionId: "always", kind: "allow_always", name: "Always allow" },
-      { optionId: "reject", kind: "reject_once", name: "Reject" },
-    ]
-
-    constructor(connection: AgentSideConnection, config: ACPConfig) {
-      this.connection = connection
-      this.config = config
-      this.sdk = config.sdk
-      this.sessionManager = new ACPSessionManager(this.sdk)
-      this.startEventSubscription()
-    }
+  private startEventSubscription() {
+    if (this.eventStarted) return
+    this.eventStarted = true
+    this.runEventSubscription().catch((error) => {
+      if (this.eventAbort.signal.aborted) return
+      log.error("event subscription failed", { error })
+    })
+  }
 
-    private startEventSubscription() {
-      if (this.eventStarted) return
-      this.eventStarted = true
-      this.runEventSubscription().catch((error) => {
-        if (this.eventAbort.signal.aborted) return
-        log.error("event subscription failed", { error })
+  private async runEventSubscription() {
+    while (true) {
+      if (this.eventAbort.signal.aborted) return
+      const events = await this.sdk.global.event({
+        signal: this.eventAbort.signal,
       })
-    }
-
-    private async runEventSubscription() {
-      while (true) {
+      for await (const event of events.stream) {
         if (this.eventAbort.signal.aborted) return
-        const events = await this.sdk.global.event({
-          signal: this.eventAbort.signal,
+        const payload = event?.payload
+        if (!payload) continue
+        await this.handleEvent(payload as Event).catch((error) => {
+          log.error("failed to handle event", { error, type: payload.type })
         })
-        for await (const event of events.stream) {
-          if (this.eventAbort.signal.aborted) return
-          const payload = event?.payload
-          if (!payload) continue
-          await this.handleEvent(payload as Event).catch((error) => {
-            log.error("failed to handle event", { error, type: payload.type })
-          })
-        }
       }
     }
+  }
 
-    private async handleEvent(event: Event) {
-      switch (event.type) {
-        case "permission.asked": {
-          const permission = event.properties
-          const session = this.sessionManager.tryGet(permission.sessionID)
-          if (!session) return
-
-          const prev = this.permissionQueues.get(permission.sessionID) ?? Promise.resolve()
-          const next = prev
-            .then(async () => {
-              const directory = session.cwd
-
-              const res = await this.connection
-                .requestPermission({
-                  sessionId: permission.sessionID,
-                  toolCall: {
-                    toolCallId: permission.tool?.callID ?? permission.id,
-                    status: "pending",
-                    title: permission.permission,
-                    rawInput: permission.metadata,
-                    kind: toToolKind(permission.permission),
-                    locations: toLocations(permission.permission, permission.metadata),
-                  },
-                  options: this.permissionOptions,
-                })
-                .catch(async (error) => {
-                  log.error("failed to request permission from ACP", {
-                    error,
-                    permissionID: permission.id,
-                    sessionID: permission.sessionID,
-                  })
-                  await this.sdk.permission.reply({
-                    requestID: permission.id,
-                    reply: "reject",
-                    directory,
-                  })
-                  return undefined
+  private async handleEvent(event: Event) {
+    switch (event.type) {
+      case "permission.asked": {
+        const permission = event.properties
+        const session = this.sessionManager.tryGet(permission.sessionID)
+        if (!session) return
+
+        const prev = this.permissionQueues.get(permission.sessionID) ?? Promise.resolve()
+        const next = prev
+          .then(async () => {
+            const directory = session.cwd
+
+            const res = await this.connection
+              .requestPermission({
+                sessionId: permission.sessionID,
+                toolCall: {
+                  toolCallId: permission.tool?.callID ?? permission.id,
+                  status: "pending",
+                  title: permission.permission,
+                  rawInput: permission.metadata,
+                  kind: toToolKind(permission.permission),
+                  locations: toLocations(permission.permission, permission.metadata),
+                },
+                options: this.permissionOptions,
+              })
+              .catch(async (error) => {
+                log.error("failed to request permission from ACP", {
+                  error,
+                  permissionID: permission.id,
+                  sessionID: permission.sessionID,
                 })
-
-              if (!res) return
-              if (res.outcome.outcome !== "selected") {
                 await this.sdk.permission.reply({
                   requestID: permission.id,
                   reply: "reject",
                   directory,
                 })
-                return
-              }
-
-              if (res.outcome.optionId !== "reject" && permission.permission == "edit") {
-                const metadata = permission.metadata || {}
-                const filepath = typeof metadata["filepath"] === "string" ? metadata["filepath"] : ""
-                const diff = typeof metadata["diff"] === "string" ? metadata["diff"] : ""
-                const content = (await Filesystem.exists(filepath)) ? await Filesystem.readText(filepath) : ""
-                const newContent = getNewContent(content, diff)
-
-                if (newContent) {
-                  void this.connection.writeTextFile({
-                    sessionId: session.id,
-                    path: filepath,
-                    content: newContent,
-                  })
-                }
-              }
+                return undefined
+              })
 
+            if (!res) return
+            if (res.outcome.outcome !== "selected") {
               await this.sdk.permission.reply({
                 requestID: permission.id,
-                reply: res.outcome.optionId as "once" | "always" | "reject",
+                reply: "reject",
                 directory,
               })
-            })
-            .catch((error) => {
-              log.error("failed to handle permission", { error, permissionID: permission.id })
-            })
-            .finally(() => {
-              if (this.permissionQueues.get(permission.sessionID) === next) {
-                this.permissionQueues.delete(permission.sessionID)
-              }
-            })
-          this.permissionQueues.set(permission.sessionID, next)
-          return
-        }
-
-        case "message.part.updated": {
-          log.info("message part updated", { event: event.properties })
-          const props = event.properties
-          const part = props.part
-          const session = this.sessionManager.tryGet(part.sessionID)
-          if (!session) return
-          const sessionId = session.id
-
-          if (part.type === "tool") {
-            await this.toolStart(sessionId, part)
-
-            switch (part.state.status) {
-              case "pending":
-                this.bashSnapshots.delete(part.callID)
-                return
-
-              case "running":
-                const output = this.bashOutput(part)
-                const content: ToolCallContent[] = []
-                if (output) {
-                  const hash = Hash.fast(output)
-                  if (part.tool === "bash") {
-                    if (this.bashSnapshots.get(part.callID) === hash) {
-                      await this.connection
-                        .sessionUpdate({
-                          sessionId,
-                          update: {
-                            sessionUpdate: "tool_call_update",
-                            toolCallId: part.callID,
-                            status: "in_progress",
-                            kind: toToolKind(part.tool),
-                            title: part.tool,
-                            locations: toLocations(part.tool, part.state.input),
-                            rawInput: part.state.input,
-                          },
-                        })
-                        .catch((error) => {
-                          log.error("failed to send tool in_progress to ACP", { error })
-                        })
-                      return
-                    }
-                    this.bashSnapshots.set(part.callID, hash)
-                  }
-                  content.push({
-                    type: "content",
-                    content: {
-                      type: "text",
-                      text: output,
-                    },
-                  })
-                }
-                await this.connection
-                  .sessionUpdate({
-                    sessionId,
-                    update: {
-                      sessionUpdate: "tool_call_update",
-                      toolCallId: part.callID,
-                      status: "in_progress",
-                      kind: toToolKind(part.tool),
-                      title: part.tool,
-                      locations: toLocations(part.tool, part.state.input),
-                      rawInput: part.state.input,
-                      ...(content.length > 0 && { content }),
-                    },
-                  })
-                  .catch((error) => {
-                    log.error("failed to send tool in_progress to ACP", { error })
-                  })
-                return
-
-              case "completed": {
-                this.toolStarts.delete(part.callID)
-                this.bashSnapshots.delete(part.callID)
-                const kind = toToolKind(part.tool)
-                const content: ToolCallContent[] = [
-                  {
-                    type: "content",
-                    content: {
-                      type: "text",
-                      text: part.state.output,
-                    },
-                  },
-                ]
-
-                if (kind === "edit") {
-                  const input = part.state.input
-                  const filePath = typeof input["filePath"] === "string" ? input["filePath"] : ""
-                  const oldText = typeof input["oldString"] === "string" ? input["oldString"] : ""
-                  const newText =
-                    typeof input["newString"] === "string"
-                      ? input["newString"]
-                      : typeof input["content"] === "string"
-                        ? input["content"]
-                        : ""
-                  content.push({
-                    type: "diff",
-                    path: filePath,
-                    oldText,
-                    newText,
-                  })
-                }
-
-                if (part.tool === "todowrite") {
-                  const parsedTodos = z.array(Todo.Info).safeParse(JSON.parse(part.state.output))
-                  if (parsedTodos.success) {
-                    await this.connection
-                      .sessionUpdate({
-                        sessionId,
-                        update: {
-                          sessionUpdate: "plan",
-                          entries: parsedTodos.data.map((todo) => {
-                            const status: PlanEntry["status"] =
-                              todo.status === "cancelled" ? "completed" : (todo.status as PlanEntry["status"])
-                            return {
-                              priority: "medium",
-                              status,
-                              content: todo.content,
-                            }
-                          }),
-                        },
-                      })
-                      .catch((error) => {
-                        log.error("failed to send session update for todo", { error })
-                      })
-                  } else {
-                    log.error("failed to parse todo output", { error: parsedTodos.error })
-                  }
-                }
+              return
+            }
 
-                await this.connection
-                  .sessionUpdate({
-                    sessionId,
-                    update: {
-                      sessionUpdate: "tool_call_update",
-                      toolCallId: part.callID,
-                      status: "completed",
-                      kind,
-                      content,
-                      title: part.state.title,
-                      rawInput: part.state.input,
-                      rawOutput: {
-                        output: part.state.output,
-                        metadata: part.state.metadata,
-                      },
-                    },
-                  })
-                  .catch((error) => {
-                    log.error("failed to send tool completed to ACP", { error })
-                  })
-                return
+            if (res.outcome.optionId !== "reject" && permission.permission == "edit") {
+              const metadata = permission.metadata || {}
+              const filepath = typeof metadata["filepath"] === "string" ? metadata["filepath"] : ""
+              const diff = typeof metadata["diff"] === "string" ? metadata["diff"] : ""
+              const content = (await Filesystem.exists(filepath)) ? await Filesystem.readText(filepath) : ""
+              const newContent = getNewContent(content, diff)
+
+              if (newContent) {
+                void this.connection.writeTextFile({
+                  sessionId: session.id,
+                  path: filepath,
+                  content: newContent,
+                })
               }
-              case "error":
-                this.toolStarts.delete(part.callID)
-                this.bashSnapshots.delete(part.callID)
-                await this.connection
-                  .sessionUpdate({
-                    sessionId,
-                    update: {
-                      sessionUpdate: "tool_call_update",
-                      toolCallId: part.callID,
-                      status: "failed",
-                      kind: toToolKind(part.tool),
-                      title: part.tool,
-                      rawInput: part.state.input,
-                      content: [
-                        {
-                          type: "content",
-                          content: {
-                            type: "text",
-                            text: part.state.error,
-                          },
-                        },
-                      ],
-                      rawOutput: {
-                        error: part.state.error,
-                        metadata: part.state.metadata,
-                      },
-                    },
-                  })
-                  .catch((error) => {
-                    log.error("failed to send tool error to ACP", { error })
-                  })
-                return
             }
-          }
 
-          // ACP clients already know the prompt they just submitted, so replaying
-          // live user parts duplicates the message. We still replay user history in
-          // loadSession() and forkSession() via processMessage().
-          if (part.type !== "text" && part.type !== "file") return
-
-          return
-        }
-
-        case "message.part.delta": {
-          const props = event.properties
-          const session = this.sessionManager.tryGet(props.sessionID)
-          if (!session) return
-          const sessionId = session.id
-
-          const message = await this.sdk.session
-            .message(
-              {
-                sessionID: props.sessionID,
-                messageID: props.messageID,
-                directory: session.cwd,
-              },
-              { throwOnError: true },
-            )
-            .then((x) => x.data)
-            .catch((error) => {
-              log.error("unexpected error when fetching message", { error })
-              return undefined
-            })
-
-          if (!message || message.info.role !== "assistant") return
-
-          const part = message.parts.find((p) => p.id === props.partID)
-          if (!part) return
-
-          if (part.type === "text" && props.field === "text" && part.ignored !== true) {
-            await this.connection
-              .sessionUpdate({
-                sessionId,
-                update: {
-                  sessionUpdate: "agent_message_chunk",
-                  messageId: props.messageID,
-                  content: {
-                    type: "text",
-                    text: props.delta,
-                  },
-                },
-              })
-              .catch((error) => {
-                log.error("failed to send text delta to ACP", { error })
-              })
-            return
-          }
-
-          if (part.type === "reasoning" && props.field === "text") {
-            await this.connection
-              .sessionUpdate({
-                sessionId,
-                update: {
-                  sessionUpdate: "agent_thought_chunk",
-                  messageId: props.messageID,
-                  content: {
-                    type: "text",
-                    text: props.delta,
-                  },
-                },
-              })
-              .catch((error) => {
-                log.error("failed to send reasoning delta to ACP", { error })
-              })
-          }
-          return
-        }
-      }
-    }
-
-    async initialize(params: InitializeRequest): Promise<InitializeResponse> {
-      log.info("initialize", { protocolVersion: params.protocolVersion })
-
-      const authMethod: AuthMethod = {
-        description: "Run `opencode auth login` in the terminal",
-        name: "Login with opencode",
-        id: "opencode-login",
-      }
-
-      // If client supports terminal-auth capability, use that instead.
-      if (params.clientCapabilities?._meta?.["terminal-auth"] === true) {
-        authMethod._meta = {
-          "terminal-auth": {
-            command: "opencode",
-            args: ["auth", "login"],
-            label: "OpenCode Login",
-          },
-        }
-      }
-
-      return {
-        protocolVersion: 1,
-        agentCapabilities: {
-          loadSession: true,
-          mcpCapabilities: {
-            http: true,
-            sse: true,
-          },
-          promptCapabilities: {
-            embeddedContext: true,
-            image: true,
-          },
-          sessionCapabilities: {
-            fork: {},
-            list: {},
-            resume: {},
-          },
-        },
-        authMethods: [authMethod],
-        agentInfo: {
-          name: "OpenCode",
-          version: InstallationVersion,
-        },
-      }
-    }
-
-    async authenticate(_params: AuthenticateRequest) {
-      throw new Error("Authentication not implemented")
-    }
-
-    async newSession(params: NewSessionRequest) {
-      const directory = params.cwd
-      try {
-        const model = await defaultModel(this.config, directory)
-
-        // Store ACP session state
-        const state = await this.sessionManager.create(params.cwd, params.mcpServers, model)
-        const sessionId = state.id
-
-        log.info("creating_session", { sessionId, mcpServers: params.mcpServers.length })
-
-        const load = await this.loadSessionMode({
-          cwd: directory,
-          mcpServers: params.mcpServers,
-          sessionId,
-        })
-
-        return {
-          sessionId,
-          configOptions: load.configOptions,
-          models: load.models,
-          modes: load.modes,
-          _meta: load._meta,
-        }
-      } catch (e) {
-        const error = MessageV2.fromError(e, {
-          providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
-        })
-        if (LoadAPIKeyError.isInstance(error)) {
-          throw RequestError.authRequired()
-        }
-        throw e
-      }
-    }
-
-    async loadSession(params: LoadSessionRequest) {
-      const directory = params.cwd
-      const sessionId = params.sessionId
-
-      try {
-        const model = await defaultModel(this.config, directory)
-
-        // Store ACP session state
-        await this.sessionManager.load(sessionId, params.cwd, params.mcpServers, model)
-
-        log.info("load_session", { sessionId, mcpServers: params.mcpServers.length })
-
-        const result = await this.loadSessionMode({
-          cwd: directory,
-          mcpServers: params.mcpServers,
-          sessionId,
-        })
-
-        // Replay session history
-        const messages = await this.sdk.session
-          .messages(
-            {
-              sessionID: sessionId,
+            await this.sdk.permission.reply({
+              requestID: permission.id,
+              reply: res.outcome.optionId as "once" | "always" | "reject",
               directory,
-            },
-            { throwOnError: true },
-          )
-          .then((x) => x.data)
-          .catch((err) => {
-            log.error("unexpected error when fetching message", { error: err })
-            return undefined
-          })
-
-        const lastUser = messages?.findLast((m) => m.info.role === "user")?.info
-        if (lastUser?.role === "user") {
-          result.models.currentModelId = `${lastUser.model.providerID}/${lastUser.model.modelID}`
-          this.sessionManager.setModel(sessionId, {
-            providerID: ProviderID.make(lastUser.model.providerID),
-            modelID: ModelID.make(lastUser.model.modelID),
+            })
           })
-          if (result.modes?.availableModes.some((m) => m.id === lastUser.agent)) {
-            result.modes.currentModeId = lastUser.agent
-            this.sessionManager.setMode(sessionId, lastUser.agent)
-          }
-          result.configOptions = buildConfigOptions({
-            currentModelId: result.models.currentModelId,
-            availableModels: result.models.availableModels,
-            modes: result.modes,
+          .catch((error) => {
+            log.error("failed to handle permission", { error, permissionID: permission.id })
           })
-        }
-
-        for (const msg of messages ?? []) {
-          log.debug("replay message", msg)
-          await this.processMessage(msg)
-        }
-
-        await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
-
-        return result
-      } catch (e) {
-        const error = MessageV2.fromError(e, {
-          providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
-        })
-        if (LoadAPIKeyError.isInstance(error)) {
-          throw RequestError.authRequired()
-        }
-        throw e
-      }
-    }
-
-    async listSessions(params: ListSessionsRequest): Promise<ListSessionsResponse> {
-      try {
-        const cursor = params.cursor ? Number(params.cursor) : undefined
-        const limit = 100
-
-        const sessions = await this.sdk.session
-          .list(
-            {
-              directory: params.cwd ?? undefined,
-              roots: true,
-            },
-            { throwOnError: true },
-          )
-          .then((x) => x.data ?? [])
-
-        const sorted = sessions.toSorted((a, b) => b.time.updated - a.time.updated)
-        const filtered = cursor ? sorted.filter((s) => s.time.updated < cursor) : sorted
-        const page = filtered.slice(0, limit)
-
-        const entries: SessionInfo[] = page.map((session) => ({
-          sessionId: session.id,
-          cwd: session.directory,
-          title: session.title,
-          updatedAt: new Date(session.time.updated).toISOString(),
-        }))
-
-        const last = page[page.length - 1]
-        const next = filtered.length > limit && last ? String(last.time.updated) : undefined
-
-        const response: ListSessionsResponse = {
-          sessions: entries,
-        }
-        if (next) response.nextCursor = next
-        return response
-      } catch (e) {
-        const error = MessageV2.fromError(e, {
-          providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
-        })
-        if (LoadAPIKeyError.isInstance(error)) {
-          throw RequestError.authRequired()
-        }
-        throw e
-      }
-    }
-
-    async unstable_forkSession(params: ForkSessionRequest): Promise<ForkSessionResponse> {
-      const directory = params.cwd
-      const mcpServers = params.mcpServers ?? []
-
-      try {
-        const model = await defaultModel(this.config, directory)
-
-        const forked = await this.sdk.session
-          .fork(
-            {
-              sessionID: params.sessionId,
-              directory,
-            },
-            { throwOnError: true },
-          )
-          .then((x) => x.data)
-
-        if (!forked) {
-          throw new Error("Fork session returned no data")
-        }
-
-        const sessionId = forked.id
-        await this.sessionManager.load(sessionId, directory, mcpServers, model)
-
-        log.info("fork_session", { sessionId, mcpServers: mcpServers.length })
-
-        const mode = await this.loadSessionMode({
-          cwd: directory,
-          mcpServers,
-          sessionId,
-        })
-
-        const messages = await this.sdk.session
-          .messages(
-            {
-              sessionID: sessionId,
-              directory,
-            },
-            { throwOnError: true },
-          )
-          .then((x) => x.data)
-          .catch((err) => {
-            log.error("unexpected error when fetching message", { error: err })
-            return undefined
+          .finally(() => {
+            if (this.permissionQueues.get(permission.sessionID) === next) {
+              this.permissionQueues.delete(permission.sessionID)
+            }
           })
-
-        for (const msg of messages ?? []) {
-          log.debug("replay message", msg)
-          await this.processMessage(msg)
-        }
-
-        await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
-
-        return mode
-      } catch (e) {
-        const error = MessageV2.fromError(e, {
-          providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
-        })
-        if (LoadAPIKeyError.isInstance(error)) {
-          throw RequestError.authRequired()
-        }
-        throw e
-      }
-    }
-
-    async unstable_resumeSession(params: ResumeSessionRequest): Promise<ResumeSessionResponse> {
-      const directory = params.cwd
-      const sessionId = params.sessionId
-      const mcpServers = params.mcpServers ?? []
-
-      try {
-        const model = await defaultModel(this.config, directory)
-        await this.sessionManager.load(sessionId, directory, mcpServers, model)
-
-        log.info("resume_session", { sessionId, mcpServers: mcpServers.length })
-
-        const result = await this.loadSessionMode({
-          cwd: directory,
-          mcpServers,
-          sessionId,
-        })
-
-        await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
-
-        return result
-      } catch (e) {
-        const error = MessageV2.fromError(e, {
-          providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
-        })
-        if (LoadAPIKeyError.isInstance(error)) {
-          throw RequestError.authRequired()
-        }
-        throw e
+        this.permissionQueues.set(permission.sessionID, next)
+        return
       }
-    }
 
-    private async processMessage(message: SessionMessageResponse) {
-      log.debug("process message", message)
-      if (message.info.role !== "assistant" && message.info.role !== "user") return
-      const sessionId = message.info.sessionID
+      case "message.part.updated": {
+        log.info("message part updated", { event: event.properties })
+        const props = event.properties
+        const part = props.part
+        const session = this.sessionManager.tryGet(part.sessionID)
+        if (!session) return
+        const sessionId = session.id
 
-      for (const part of message.parts) {
         if (part.type === "tool") {
           await this.toolStart(sessionId, part)
+
           switch (part.state.status) {
             case "pending":
               this.bashSnapshots.delete(part.callID)
-              break
+              return
+
             case "running":
               const output = this.bashOutput(part)
-              const runningContent: ToolCallContent[] = []
+              const content: ToolCallContent[] = []
               if (output) {
-                runningContent.push({
+                const hash = Hash.fast(output)
+                if (part.tool === "bash") {
+                  if (this.bashSnapshots.get(part.callID) === hash) {
+                    await this.connection
+                      .sessionUpdate({
+                        sessionId,
+                        update: {
+                          sessionUpdate: "tool_call_update",
+                          toolCallId: part.callID,
+                          status: "in_progress",
+                          kind: toToolKind(part.tool),
+                          title: part.tool,
+                          locations: toLocations(part.tool, part.state.input),
+                          rawInput: part.state.input,
+                        },
+                      })
+                      .catch((error) => {
+                        log.error("failed to send tool in_progress to ACP", { error })
+                      })
+                    return
+                  }
+                  this.bashSnapshots.set(part.callID, hash)
+                }
+                content.push({
                   type: "content",
                   content: {
                     type: "text",
@@ -862,14 +331,15 @@ export namespace ACP {
                     title: part.tool,
                     locations: toLocations(part.tool, part.state.input),
                     rawInput: part.state.input,
-                    ...(runningContent.length > 0 && { content: runningContent }),
+                    ...(content.length > 0 && { content }),
                   },
                 })
-                .catch((err) => {
-                  log.error("failed to send tool in_progress to ACP", { error: err })
+                .catch((error) => {
+                  log.error("failed to send tool in_progress to ACP", { error })
                 })
-              break
-            case "completed":
+              return
+
+            case "completed": {
               this.toolStarts.delete(part.callID)
               this.bashSnapshots.delete(part.callID)
               const kind = toToolKind(part.tool)
@@ -920,8 +390,8 @@ export namespace ACP {
                         }),
                       },
                     })
-                    .catch((err) => {
-                      log.error("failed to send session update for todo", { error: err })
+                    .catch((error) => {
+                      log.error("failed to send session update for todo", { error })
                     })
                 } else {
                   log.error("failed to parse todo output", { error: parsedTodos.error })
@@ -945,10 +415,11 @@ export namespace ACP {
                     },
                   },
                 })
-                .catch((err) => {
-                  log.error("failed to send tool completed to ACP", { error: err })
+                .catch((error) => {
+                  log.error("failed to send tool completed to ACP", { error })
                 })
-              break
+              return
+            }
             case "error":
               this.toolStarts.delete(part.callID)
               this.bashSnapshots.delete(part.callID)
@@ -977,865 +448,1394 @@ export namespace ACP {
                     },
                   },
                 })
-                .catch((err) => {
-                  log.error("failed to send tool error to ACP", { error: err })
+                .catch((error) => {
+                  log.error("failed to send tool error to ACP", { error })
                 })
-              break
-          }
-        } else if (part.type === "text") {
-          if (part.text) {
-            const audience: Role[] | undefined = part.synthetic ? ["assistant"] : part.ignored ? ["user"] : undefined
-            await this.connection
-              .sessionUpdate({
-                sessionId,
-                update: {
-                  sessionUpdate: message.info.role === "user" ? "user_message_chunk" : "agent_message_chunk",
-                  messageId: message.info.id,
-                  content: {
-                    type: "text",
-                    text: part.text,
-                    ...(audience && { annotations: { audience } }),
-                  },
-                },
-              })
-              .catch((err) => {
-                log.error("failed to send text to ACP", { error: err })
-              })
+              return
           }
-        } else if (part.type === "file") {
-          // Replay file attachments as appropriate ACP content blocks.
-          // OpenCode stores files internally as { type: "file", url, filename, mime }.
-          // We convert these back to ACP blocks based on the URL scheme and MIME type:
-          // - file:// URLs → resource_link
-          // - data: URLs with image/* → image block
-          // - data: URLs with text/* or application/json → resource with text
-          // - data: URLs with other types → resource with blob
-          const url = part.url
-          const filename = part.filename ?? "file"
-          const mime = part.mime || "application/octet-stream"
-          const messageChunk = message.info.role === "user" ? "user_message_chunk" : "agent_message_chunk"
-
-          if (url.startsWith("file://")) {
-            // Local file reference - send as resource_link
-            await this.connection
-              .sessionUpdate({
-                sessionId,
-                update: {
-                  sessionUpdate: messageChunk,
-                  messageId: message.info.id,
-                  content: { type: "resource_link", uri: url, name: filename, mimeType: mime },
-                },
-              })
-              .catch((err) => {
-                log.error("failed to send resource_link to ACP", { error: err })
-              })
-          } else if (url.startsWith("data:")) {
-            // Embedded content - parse data URL and send as appropriate block type
-            const base64Match = url.match(/^data:([^;]+);base64,(.*)$/)
-            const dataMime = base64Match?.[1]
-            const base64Data = base64Match?.[2] ?? ""
+        }
 
-            const effectiveMime = dataMime || mime
+        // ACP clients already know the prompt they just submitted, so replaying
+        // live user parts duplicates the message. We still replay user history in
+        // loadSession() and forkSession() via processMessage().
+        if (part.type !== "text" && part.type !== "file") return
 
-            if (effectiveMime.startsWith("image/")) {
-              // Image - send as image block
-              await this.connection
-                .sessionUpdate({
-                  sessionId,
-                  update: {
-                    sessionUpdate: messageChunk,
-                    messageId: message.info.id,
-                    content: {
-                      type: "image",
-                      mimeType: effectiveMime,
-                      data: base64Data,
-                      uri: pathToFileURL(filename).href,
-                    },
-                  },
-                })
-                .catch((err) => {
-                  log.error("failed to send image to ACP", { error: err })
-                })
-            } else {
-              // Non-image: text types get decoded, binary types stay as blob
-              const isText = effectiveMime.startsWith("text/") || effectiveMime === "application/json"
-              const fileUri = pathToFileURL(filename).href
-              const resource = isText
-                ? {
-                    uri: fileUri,
-                    mimeType: effectiveMime,
-                    text: Buffer.from(base64Data, "base64").toString("utf-8"),
-                  }
-                : { uri: fileUri, mimeType: effectiveMime, blob: base64Data }
+        return
+      }
 
-              await this.connection
-                .sessionUpdate({
-                  sessionId,
-                  update: {
-                    sessionUpdate: messageChunk,
-                    messageId: message.info.id,
-                    content: { type: "resource", resource },
-                  },
-                })
-                .catch((err) => {
-                  log.error("failed to send resource to ACP", { error: err })
-                })
-            }
-          }
-          // URLs that don't match file:// or data: are skipped (unsupported)
-        } else if (part.type === "reasoning") {
-          if (part.text) {
-            await this.connection
-              .sessionUpdate({
-                sessionId,
-                update: {
-                  sessionUpdate: "agent_thought_chunk",
-                  messageId: message.info.id,
-                  content: {
-                    type: "text",
-                    text: part.text,
-                  },
+      case "message.part.delta": {
+        const props = event.properties
+        const session = this.sessionManager.tryGet(props.sessionID)
+        if (!session) return
+        const sessionId = session.id
+
+        const message = await this.sdk.session
+          .message(
+            {
+              sessionID: props.sessionID,
+              messageID: props.messageID,
+              directory: session.cwd,
+            },
+            { throwOnError: true },
+          )
+          .then((x) => x.data)
+          .catch((error) => {
+            log.error("unexpected error when fetching message", { error })
+            return undefined
+          })
+
+        if (!message || message.info.role !== "assistant") return
+
+        const part = message.parts.find((p) => p.id === props.partID)
+        if (!part) return
+
+        if (part.type === "text" && props.field === "text" && part.ignored !== true) {
+          await this.connection
+            .sessionUpdate({
+              sessionId,
+              update: {
+                sessionUpdate: "agent_message_chunk",
+                messageId: props.messageID,
+                content: {
+                  type: "text",
+                  text: props.delta,
                 },
-              })
-              .catch((err) => {
-                log.error("failed to send reasoning to ACP", { error: err })
-              })
-          }
+              },
+            })
+            .catch((error) => {
+              log.error("failed to send text delta to ACP", { error })
+            })
+          return
+        }
+
+        if (part.type === "reasoning" && props.field === "text") {
+          await this.connection
+            .sessionUpdate({
+              sessionId,
+              update: {
+                sessionUpdate: "agent_thought_chunk",
+                messageId: props.messageID,
+                content: {
+                  type: "text",
+                  text: props.delta,
+                },
+              },
+            })
+            .catch((error) => {
+              log.error("failed to send reasoning delta to ACP", { error })
+            })
         }
+        return
       }
     }
+  }
 
-    private bashOutput(part: ToolPart) {
-      if (part.tool !== "bash") return
-      if (!("metadata" in part.state) || !part.state.metadata || typeof part.state.metadata !== "object") return
-      const output = part.state.metadata["output"]
-      if (typeof output !== "string") return
-      return output
-    }
+  async initialize(params: InitializeRequest): Promise<InitializeResponse> {
+    log.info("initialize", { protocolVersion: params.protocolVersion })
 
-    private async toolStart(sessionId: string, part: ToolPart) {
-      if (this.toolStarts.has(part.callID)) return
-      this.toolStarts.add(part.callID)
-      await this.connection
-        .sessionUpdate({
-          sessionId,
-          update: {
-            sessionUpdate: "tool_call",
-            toolCallId: part.callID,
-            title: part.tool,
-            kind: toToolKind(part.tool),
-            status: "pending",
-            locations: [],
-            rawInput: {},
-          },
-        })
-        .catch((error) => {
-          log.error("failed to send tool pending to ACP", { error })
-        })
+    const authMethod: AuthMethod = {
+      description: "Run `opencode auth login` in the terminal",
+      name: "Login with opencode",
+      id: "opencode-login",
     }
 
-    private async loadAvailableModes(directory: string): Promise<ModeOption[]> {
-      const agents = await this.config.sdk.app
-        .agents(
-          {
-            directory,
-          },
-          { throwOnError: true },
-        )
-        .then((resp) => resp.data!)
-
-      return agents
-        .filter((agent) => agent.mode !== "subagent" && !agent.hidden)
-        .map((agent) => ({
-          id: agent.name,
-          name: agent.name,
-          description: agent.description,
-        }))
+    // If client supports terminal-auth capability, use that instead.
+    if (params.clientCapabilities?._meta?.["terminal-auth"] === true) {
+      authMethod._meta = {
+        "terminal-auth": {
+          command: "opencode",
+          args: ["auth", "login"],
+          label: "OpenCode Login",
+        },
+      }
     }
 
-    private async resolveModeState(
-      directory: string,
-      sessionId: string,
-    ): Promise<{ availableModes: ModeOption[]; currentModeId?: string }> {
-      const availableModes = await this.loadAvailableModes(directory)
-      const currentModeId =
-        this.sessionManager.get(sessionId).modeId ||
-        (await (async () => {
-          if (!availableModes.length) return undefined
-          const defaultAgentName = await AppRuntime.runPromise(AgentModule.Service.use((svc) => svc.defaultAgent()))
-          const resolvedModeId =
-            availableModes.find((mode) => mode.name === defaultAgentName)?.id ?? availableModes[0].id
-          this.sessionManager.setMode(sessionId, resolvedModeId)
-          return resolvedModeId
-        })())
-
-      return { availableModes, currentModeId }
+    return {
+      protocolVersion: 1,
+      agentCapabilities: {
+        loadSession: true,
+        mcpCapabilities: {
+          http: true,
+          sse: true,
+        },
+        promptCapabilities: {
+          embeddedContext: true,
+          image: true,
+        },
+        sessionCapabilities: {
+          fork: {},
+          list: {},
+          resume: {},
+        },
+      },
+      authMethods: [authMethod],
+      agentInfo: {
+        name: "OpenCode",
+        version: InstallationVersion,
+      },
     }
+  }
 
-    private async loadSessionMode(params: LoadSessionRequest) {
-      const directory = params.cwd
+  async authenticate(_params: AuthenticateRequest) {
+    throw new Error("Authentication not implemented")
+  }
+
+  async newSession(params: NewSessionRequest) {
+    const directory = params.cwd
+    try {
       const model = await defaultModel(this.config, directory)
-      const sessionId = params.sessionId
-
-      const providers = await this.sdk.config.providers({ directory }).then((x) => x.data!.providers)
-      const entries = sortProvidersByName(providers)
-      const availableVariants = modelVariantsFromProviders(entries, model)
-      const currentVariant = this.sessionManager.getVariant(sessionId)
-      if (currentVariant && !availableVariants.includes(currentVariant)) {
-        this.sessionManager.setVariant(sessionId, undefined)
+
+      // Store ACP session state
+      const state = await this.sessionManager.create(params.cwd, params.mcpServers, model)
+      const sessionId = state.id
+
+      log.info("creating_session", { sessionId, mcpServers: params.mcpServers.length })
+
+      const load = await this.loadSessionMode({
+        cwd: directory,
+        mcpServers: params.mcpServers,
+        sessionId,
+      })
+
+      return {
+        sessionId,
+        configOptions: load.configOptions,
+        models: load.models,
+        modes: load.modes,
+        _meta: load._meta,
       }
-      const availableModels = buildAvailableModels(entries, { includeVariants: true })
-      const modeState = await this.resolveModeState(directory, sessionId)
-      const currentModeId = modeState.currentModeId
-      const modes = currentModeId
-        ? {
-            availableModes: modeState.availableModes,
-            currentModeId,
-          }
-        : undefined
+    } catch (e) {
+      const error = MessageV2.fromError(e, {
+        providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
+      })
+      if (LoadAPIKeyError.isInstance(error)) {
+        throw RequestError.authRequired()
+      }
+      throw e
+    }
+  }
 
-      const commands = await this.config.sdk.command
-        .list(
+  async loadSession(params: LoadSessionRequest) {
+    const directory = params.cwd
+    const sessionId = params.sessionId
+
+    try {
+      const model = await defaultModel(this.config, directory)
+
+      // Store ACP session state
+      await this.sessionManager.load(sessionId, params.cwd, params.mcpServers, model)
+
+      log.info("load_session", { sessionId, mcpServers: params.mcpServers.length })
+
+      const result = await this.loadSessionMode({
+        cwd: directory,
+        mcpServers: params.mcpServers,
+        sessionId,
+      })
+
+      // Replay session history
+      const messages = await this.sdk.session
+        .messages(
           {
+            sessionID: sessionId,
             directory,
           },
           { throwOnError: true },
         )
-        .then((resp) => resp.data!)
-
-      const availableCommands = commands.map((command) => ({
-        name: command.name,
-        description: command.description ?? "",
-      }))
-      const names = new Set(availableCommands.map((c) => c.name))
-      if (!names.has("compact"))
-        availableCommands.push({
-          name: "compact",
-          description: "compact the session",
+        .then((x) => x.data)
+        .catch((err) => {
+          log.error("unexpected error when fetching message", { error: err })
+          return undefined
         })
 
-      const mcpServers: Record<string, ConfigMCP.Info> = {}
-      for (const server of params.mcpServers) {
-        if ("type" in server) {
-          mcpServers[server.name] = {
-            url: server.url,
-            headers: server.headers.reduce<Record<string, string>>((acc, { name, value }) => {
-              acc[name] = value
-              return acc
-            }, {}),
-            type: "remote",
-          }
-        } else {
-          mcpServers[server.name] = {
-            type: "local",
-            command: [server.command, ...server.args],
-            environment: server.env.reduce<Record<string, string>>((acc, { name, value }) => {
-              acc[name] = value
-              return acc
-            }, {}),
-          }
+      const lastUser = messages?.findLast((m) => m.info.role === "user")?.info
+      if (lastUser?.role === "user") {
+        result.models.currentModelId = `${lastUser.model.providerID}/${lastUser.model.modelID}`
+        this.sessionManager.setModel(sessionId, {
+          providerID: ProviderID.make(lastUser.model.providerID),
+          modelID: ModelID.make(lastUser.model.modelID),
+        })
+        if (result.modes?.availableModes.some((m) => m.id === lastUser.agent)) {
+          result.modes.currentModeId = lastUser.agent
+          this.sessionManager.setMode(sessionId, lastUser.agent)
         }
+        result.configOptions = buildConfigOptions({
+          currentModelId: result.models.currentModelId,
+          availableModels: result.models.availableModels,
+          modes: result.modes,
+        })
       }
 
-      await Promise.all(
-        Object.entries(mcpServers).map(async ([key, mcp]) => {
-          await this.sdk.mcp
-            .add(
-              {
-                directory,
-                name: key,
-                config: mcp,
-              },
-              { throwOnError: true },
-            )
-            .catch((error) => {
-              log.error("failed to add mcp server", { name: key, error })
-            })
-        }),
-      )
+      for (const msg of messages ?? []) {
+        log.debug("replay message", msg)
+        await this.processMessage(msg)
+      }
 
-      setTimeout(() => {
-        void this.connection.sessionUpdate({
-          sessionId,
-          update: {
-            sessionUpdate: "available_commands_update",
-            availableCommands,
-          },
-        })
-      }, 0)
+      await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
 
-      return {
-        sessionId,
-        models: {
-          currentModelId: formatModelIdWithVariant(model, currentVariant, availableVariants, true),
-          availableModels,
-        },
-        modes,
-        configOptions: buildConfigOptions({
-          currentModelId: formatModelIdWithVariant(model, currentVariant, availableVariants, true),
-          availableModels,
-          modes,
-        }),
-        _meta: buildVariantMeta({
-          model,
-          variant: this.sessionManager.getVariant(sessionId),
-          availableVariants,
-        }),
+      return result
+    } catch (e) {
+      const error = MessageV2.fromError(e, {
+        providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
+      })
+      if (LoadAPIKeyError.isInstance(error)) {
+        throw RequestError.authRequired()
       }
+      throw e
     }
+  }
 
-    async unstable_setSessionModel(params: SetSessionModelRequest) {
-      const session = this.sessionManager.get(params.sessionId)
-      const providers = await this.sdk.config
-        .providers({ directory: session.cwd }, { throwOnError: true })
-        .then((x) => x.data!.providers)
+  async listSessions(params: ListSessionsRequest): Promise<ListSessionsResponse> {
+    try {
+      const cursor = params.cursor ? Number(params.cursor) : undefined
+      const limit = 100
 
-      const selection = parseModelSelection(params.modelId, providers)
-      this.sessionManager.setModel(session.id, selection.model)
-      this.sessionManager.setVariant(session.id, selection.variant)
+      const sessions = await this.sdk.session
+        .list(
+          {
+            directory: params.cwd ?? undefined,
+            roots: true,
+          },
+          { throwOnError: true },
+        )
+        .then((x) => x.data ?? [])
 
-      const entries = sortProvidersByName(providers)
-      const availableVariants = modelVariantsFromProviders(entries, selection.model)
+      const sorted = sessions.toSorted((a, b) => b.time.updated - a.time.updated)
+      const filtered = cursor ? sorted.filter((s) => s.time.updated < cursor) : sorted
+      const page = filtered.slice(0, limit)
 
-      return {
-        _meta: buildVariantMeta({
-          model: selection.model,
-          variant: selection.variant,
-          availableVariants,
-        }),
+      const entries: SessionInfo[] = page.map((session) => ({
+        sessionId: session.id,
+        cwd: session.directory,
+        title: session.title,
+        updatedAt: new Date(session.time.updated).toISOString(),
+      }))
+
+      const last = page[page.length - 1]
+      const next = filtered.length > limit && last ? String(last.time.updated) : undefined
+
+      const response: ListSessionsResponse = {
+        sessions: entries,
+      }
+      if (next) response.nextCursor = next
+      return response
+    } catch (e) {
+      const error = MessageV2.fromError(e, {
+        providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
+      })
+      if (LoadAPIKeyError.isInstance(error)) {
+        throw RequestError.authRequired()
       }
+      throw e
     }
+  }
 
-    async setSessionMode(params: SetSessionModeRequest): Promise<SetSessionModeResponse | void> {
-      const session = this.sessionManager.get(params.sessionId)
-      const availableModes = await this.loadAvailableModes(session.cwd)
-      if (!availableModes.some((mode) => mode.id === params.modeId)) {
-        throw new Error(`Agent not found: ${params.modeId}`)
+  async unstable_forkSession(params: ForkSessionRequest): Promise<ForkSessionResponse> {
+    const directory = params.cwd
+    const mcpServers = params.mcpServers ?? []
+
+    try {
+      const model = await defaultModel(this.config, directory)
+
+      const forked = await this.sdk.session
+        .fork(
+          {
+            sessionID: params.sessionId,
+            directory,
+          },
+          { throwOnError: true },
+        )
+        .then((x) => x.data)
+
+      if (!forked) {
+        throw new Error("Fork session returned no data")
       }
-      this.sessionManager.setMode(params.sessionId, params.modeId)
-    }
 
-    async setSessionConfigOption(params: SetSessionConfigOptionRequest): Promise<SetSessionConfigOptionResponse> {
-      const session = this.sessionManager.get(params.sessionId)
-      const providers = await this.sdk.config
-        .providers({ directory: session.cwd }, { throwOnError: true })
-        .then((x) => x.data!.providers)
-      const entries = sortProvidersByName(providers)
-
-      if (params.configId === "model") {
-        if (typeof params.value !== "string") throw RequestError.invalidParams("model value must be a string")
-        const selection = parseModelSelection(params.value, providers)
-        this.sessionManager.setModel(session.id, selection.model)
-        this.sessionManager.setVariant(session.id, selection.variant)
-      } else if (params.configId === "mode") {
-        if (typeof params.value !== "string") throw RequestError.invalidParams("mode value must be a string")
-        const availableModes = await this.loadAvailableModes(session.cwd)
-        if (!availableModes.some((mode) => mode.id === params.value)) {
-          throw RequestError.invalidParams(JSON.stringify({ error: `Mode not found: ${params.value}` }))
-        }
-        this.sessionManager.setMode(session.id, params.value)
-      } else {
-        throw RequestError.invalidParams(JSON.stringify({ error: `Unknown config option: ${params.configId}` }))
+      const sessionId = forked.id
+      await this.sessionManager.load(sessionId, directory, mcpServers, model)
+
+      log.info("fork_session", { sessionId, mcpServers: mcpServers.length })
+
+      const mode = await this.loadSessionMode({
+        cwd: directory,
+        mcpServers,
+        sessionId,
+      })
+
+      const messages = await this.sdk.session
+        .messages(
+          {
+            sessionID: sessionId,
+            directory,
+          },
+          { throwOnError: true },
+        )
+        .then((x) => x.data)
+        .catch((err) => {
+          log.error("unexpected error when fetching message", { error: err })
+          return undefined
+        })
+
+      for (const msg of messages ?? []) {
+        log.debug("replay message", msg)
+        await this.processMessage(msg)
       }
 
-      const updatedSession = this.sessionManager.get(session.id)
-      const model = updatedSession.model ?? (await defaultModel(this.config, session.cwd))
-      const availableVariants = modelVariantsFromProviders(entries, model)
-      const currentModelId = formatModelIdWithVariant(model, updatedSession.variant, availableVariants, true)
-      const availableModels = buildAvailableModels(entries, { includeVariants: true })
-      const modeState = await this.resolveModeState(session.cwd, session.id)
-      const modes = modeState.currentModeId
-        ? { availableModes: modeState.availableModes, currentModeId: modeState.currentModeId }
-        : undefined
+      await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
 
-      return {
-        configOptions: buildConfigOptions({ currentModelId, availableModels, modes }),
+      return mode
+    } catch (e) {
+      const error = MessageV2.fromError(e, {
+        providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
+      })
+      if (LoadAPIKeyError.isInstance(error)) {
+        throw RequestError.authRequired()
       }
+      throw e
     }
+  }
+
+  async unstable_resumeSession(params: ResumeSessionRequest): Promise<ResumeSessionResponse> {
+    const directory = params.cwd
+    const sessionId = params.sessionId
+    const mcpServers = params.mcpServers ?? []
+
+    try {
+      const model = await defaultModel(this.config, directory)
+      await this.sessionManager.load(sessionId, directory, mcpServers, model)
 
-    async prompt(params: PromptRequest) {
-      const sessionID = params.sessionId
-      const session = this.sessionManager.get(sessionID)
-      const directory = session.cwd
+      log.info("resume_session", { sessionId, mcpServers: mcpServers.length })
 
-      const current = session.model
-      const model = current ?? (await defaultModel(this.config, directory))
-      if (!current) {
-        this.sessionManager.setModel(session.id, model)
+      const result = await this.loadSessionMode({
+        cwd: directory,
+        mcpServers,
+        sessionId,
+      })
+
+      await sendUsageUpdate(this.connection, this.sdk, sessionId, directory)
+
+      return result
+    } catch (e) {
+      const error = MessageV2.fromError(e, {
+        providerID: ProviderID.make(this.config.defaultModel?.providerID ?? "unknown"),
+      })
+      if (LoadAPIKeyError.isInstance(error)) {
+        throw RequestError.authRequired()
       }
-      const agent =
-        session.modeId ?? (await AppRuntime.runPromise(AgentModule.Service.use((svc) => svc.defaultAgent())))
-
-      const parts: Array<
-        | { type: "text"; text: string; synthetic?: boolean; ignored?: boolean }
-        | { type: "file"; url: string; filename: string; mime: string }
-      > = []
-      for (const part of params.prompt) {
-        switch (part.type) {
-          case "text":
-            const audience = part.annotations?.audience
-            const forAssistant = audience?.length === 1 && audience[0] === "assistant"
-            const forUser = audience?.length === 1 && audience[0] === "user"
-            parts.push({
-              type: "text" as const,
-              text: part.text,
-              ...(forAssistant && { synthetic: true }),
-              ...(forUser && { ignored: true }),
-            })
+      throw e
+    }
+  }
+
+  private async processMessage(message: SessionMessageResponse) {
+    log.debug("process message", message)
+    if (message.info.role !== "assistant" && message.info.role !== "user") return
+    const sessionId = message.info.sessionID
+
+    for (const part of message.parts) {
+      if (part.type === "tool") {
+        await this.toolStart(sessionId, part)
+        switch (part.state.status) {
+          case "pending":
+            this.bashSnapshots.delete(part.callID)
             break
-          case "image": {
-            const parsed = parseUri(part.uri ?? "")
-            const filename = parsed.type === "file" ? parsed.filename : "image"
-            if (part.data) {
-              parts.push({
-                type: "file",
-                url: `data:${part.mimeType};base64,${part.data}`,
-                filename,
-                mime: part.mimeType,
-              })
-            } else if (part.uri && part.uri.startsWith("http:")) {
-              parts.push({
-                type: "file",
-                url: part.uri,
-                filename,
-                mime: part.mimeType,
+          case "running":
+            const output = this.bashOutput(part)
+            const runningContent: ToolCallContent[] = []
+            if (output) {
+              runningContent.push({
+                type: "content",
+                content: {
+                  type: "text",
+                  text: output,
+                },
               })
             }
+            await this.connection
+              .sessionUpdate({
+                sessionId,
+                update: {
+                  sessionUpdate: "tool_call_update",
+                  toolCallId: part.callID,
+                  status: "in_progress",
+                  kind: toToolKind(part.tool),
+                  title: part.tool,
+                  locations: toLocations(part.tool, part.state.input),
+                  rawInput: part.state.input,
+                  ...(runningContent.length > 0 && { content: runningContent }),
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send tool in_progress to ACP", { error: err })
+              })
             break
-          }
+          case "completed":
+            this.toolStarts.delete(part.callID)
+            this.bashSnapshots.delete(part.callID)
+            const kind = toToolKind(part.tool)
+            const content: ToolCallContent[] = [
+              {
+                type: "content",
+                content: {
+                  type: "text",
+                  text: part.state.output,
+                },
+              },
+            ]
+
+            if (kind === "edit") {
+              const input = part.state.input
+              const filePath = typeof input["filePath"] === "string" ? input["filePath"] : ""
+              const oldText = typeof input["oldString"] === "string" ? input["oldString"] : ""
+              const newText =
+                typeof input["newString"] === "string"
+                  ? input["newString"]
+                  : typeof input["content"] === "string"
+                    ? input["content"]
+                    : ""
+              content.push({
+                type: "diff",
+                path: filePath,
+                oldText,
+                newText,
+              })
+            }
 
-          case "resource_link":
-            const parsed = parseUri(part.uri)
-            // Use the name from resource_link if available
-            if (part.name && parsed.type === "file") {
-              parsed.filename = part.name
+            if (part.tool === "todowrite") {
+              const parsedTodos = z.array(Todo.Info).safeParse(JSON.parse(part.state.output))
+              if (parsedTodos.success) {
+                await this.connection
+                  .sessionUpdate({
+                    sessionId,
+                    update: {
+                      sessionUpdate: "plan",
+                      entries: parsedTodos.data.map((todo) => {
+                        const status: PlanEntry["status"] =
+                          todo.status === "cancelled" ? "completed" : (todo.status as PlanEntry["status"])
+                        return {
+                          priority: "medium",
+                          status,
+                          content: todo.content,
+                        }
+                      }),
+                    },
+                  })
+                  .catch((err) => {
+                    log.error("failed to send session update for todo", { error: err })
+                  })
+              } else {
+                log.error("failed to parse todo output", { error: parsedTodos.error })
+              }
             }
-            parts.push(parsed)
 
+            await this.connection
+              .sessionUpdate({
+                sessionId,
+                update: {
+                  sessionUpdate: "tool_call_update",
+                  toolCallId: part.callID,
+                  status: "completed",
+                  kind,
+                  content,
+                  title: part.state.title,
+                  rawInput: part.state.input,
+                  rawOutput: {
+                    output: part.state.output,
+                    metadata: part.state.metadata,
+                  },
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send tool completed to ACP", { error: err })
+              })
             break
-
-          case "resource": {
-            const resource = part.resource
-            if ("text" in resource && resource.text) {
-              parts.push({
-                type: "text",
-                text: resource.text,
+          case "error":
+            this.toolStarts.delete(part.callID)
+            this.bashSnapshots.delete(part.callID)
+            await this.connection
+              .sessionUpdate({
+                sessionId,
+                update: {
+                  sessionUpdate: "tool_call_update",
+                  toolCallId: part.callID,
+                  status: "failed",
+                  kind: toToolKind(part.tool),
+                  title: part.tool,
+                  rawInput: part.state.input,
+                  content: [
+                    {
+                      type: "content",
+                      content: {
+                        type: "text",
+                        text: part.state.error,
+                      },
+                    },
+                  ],
+                  rawOutput: {
+                    error: part.state.error,
+                    metadata: part.state.metadata,
+                  },
+                },
               })
-            } else if ("blob" in resource && resource.blob && resource.mimeType) {
-              // Binary resource (PDFs, etc.): store as file part with data URL
-              const parsed = parseUri(resource.uri ?? "")
-              const filename = parsed.type === "file" ? parsed.filename : "file"
-              parts.push({
-                type: "file",
-                url: `data:${resource.mimeType};base64,${resource.blob}`,
-                filename,
-                mime: resource.mimeType,
+              .catch((err) => {
+                log.error("failed to send tool error to ACP", { error: err })
               })
-            }
             break
-          }
+        }
+      } else if (part.type === "text") {
+        if (part.text) {
+          const audience: Role[] | undefined = part.synthetic ? ["assistant"] : part.ignored ? ["user"] : undefined
+          await this.connection
+            .sessionUpdate({
+              sessionId,
+              update: {
+                sessionUpdate: message.info.role === "user" ? "user_message_chunk" : "agent_message_chunk",
+                messageId: message.info.id,
+                content: {
+                  type: "text",
+                  text: part.text,
+                  ...(audience && { annotations: { audience } }),
+                },
+              },
+            })
+            .catch((err) => {
+              log.error("failed to send text to ACP", { error: err })
+            })
+        }
+      } else if (part.type === "file") {
+        // Replay file attachments as appropriate ACP content blocks.
+        // OpenCode stores files internally as { type: "file", url, filename, mime }.
+        // We convert these back to ACP blocks based on the URL scheme and MIME type:
+        // - file:// URLs → resource_link
+        // - data: URLs with image/* → image block
+        // - data: URLs with text/* or application/json → resource with text
+        // - data: URLs with other types → resource with blob
+        const url = part.url
+        const filename = part.filename ?? "file"
+        const mime = part.mime || "application/octet-stream"
+        const messageChunk = message.info.role === "user" ? "user_message_chunk" : "agent_message_chunk"
+
+        if (url.startsWith("file://")) {
+          // Local file reference - send as resource_link
+          await this.connection
+            .sessionUpdate({
+              sessionId,
+              update: {
+                sessionUpdate: messageChunk,
+                messageId: message.info.id,
+                content: { type: "resource_link", uri: url, name: filename, mimeType: mime },
+              },
+            })
+            .catch((err) => {
+              log.error("failed to send resource_link to ACP", { error: err })
+            })
+        } else if (url.startsWith("data:")) {
+          // Embedded content - parse data URL and send as appropriate block type
+          const base64Match = url.match(/^data:([^;]+);base64,(.*)$/)
+          const dataMime = base64Match?.[1]
+          const base64Data = base64Match?.[2] ?? ""
 
-          default:
-            break
+          const effectiveMime = dataMime || mime
+
+          if (effectiveMime.startsWith("image/")) {
+            // Image - send as image block
+            await this.connection
+              .sessionUpdate({
+                sessionId,
+                update: {
+                  sessionUpdate: messageChunk,
+                  messageId: message.info.id,
+                  content: {
+                    type: "image",
+                    mimeType: effectiveMime,
+                    data: base64Data,
+                    uri: pathToFileURL(filename).href,
+                  },
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send image to ACP", { error: err })
+              })
+          } else {
+            // Non-image: text types get decoded, binary types stay as blob
+            const isText = effectiveMime.startsWith("text/") || effectiveMime === "application/json"
+            const fileUri = pathToFileURL(filename).href
+            const resource = isText
+              ? {
+                  uri: fileUri,
+                  mimeType: effectiveMime,
+                  text: Buffer.from(base64Data, "base64").toString("utf-8"),
+                }
+              : { uri: fileUri, mimeType: effectiveMime, blob: base64Data }
+
+            await this.connection
+              .sessionUpdate({
+                sessionId,
+                update: {
+                  sessionUpdate: messageChunk,
+                  messageId: message.info.id,
+                  content: { type: "resource", resource },
+                },
+              })
+              .catch((err) => {
+                log.error("failed to send resource to ACP", { error: err })
+              })
+          }
+        }
+        // URLs that don't match file:// or data: are skipped (unsupported)
+      } else if (part.type === "reasoning") {
+        if (part.text) {
+          await this.connection
+            .sessionUpdate({
+              sessionId,
+              update: {
+                sessionUpdate: "agent_thought_chunk",
+                messageId: message.info.id,
+                content: {
+                  type: "text",
+                  text: part.text,
+                },
+              },
+            })
+            .catch((err) => {
+              log.error("failed to send reasoning to ACP", { error: err })
+            })
         }
       }
+    }
+  }
+
+  private bashOutput(part: ToolPart) {
+    if (part.tool !== "bash") return
+    if (!("metadata" in part.state) || !part.state.metadata || typeof part.state.metadata !== "object") return
+    const output = part.state.metadata["output"]
+    if (typeof output !== "string") return
+    return output
+  }
 
-      log.info("parts", { parts })
-
-      const cmd = (() => {
-        const text = parts
-          .filter((p): p is { type: "text"; text: string } => p.type === "text")
-          .map((p) => p.text)
-          .join("")
-          .trim()
-
-        if (!text.startsWith("/")) return
-
-        const [name, ...rest] = text.slice(1).split(/\s+/)
-        return { name, args: rest.join(" ").trim() }
-      })()
-
-      const buildUsage = (msg: AssistantMessage): Usage => ({
-        totalTokens:
-          msg.tokens.input +
-          msg.tokens.output +
-          msg.tokens.reasoning +
-          (msg.tokens.cache?.read ?? 0) +
-          (msg.tokens.cache?.write ?? 0),
-        inputTokens: msg.tokens.input,
-        outputTokens: msg.tokens.output,
-        thoughtTokens: msg.tokens.reasoning || undefined,
-        cachedReadTokens: msg.tokens.cache?.read || undefined,
-        cachedWriteTokens: msg.tokens.cache?.write || undefined,
+  private async toolStart(sessionId: string, part: ToolPart) {
+    if (this.toolStarts.has(part.callID)) return
+    this.toolStarts.add(part.callID)
+    await this.connection
+      .sessionUpdate({
+        sessionId,
+        update: {
+          sessionUpdate: "tool_call",
+          toolCallId: part.callID,
+          title: part.tool,
+          kind: toToolKind(part.tool),
+          status: "pending",
+          locations: [],
+          rawInput: {},
+        },
+      })
+      .catch((error) => {
+        log.error("failed to send tool pending to ACP", { error })
       })
+  }
 
-      if (!cmd) {
-        const response = await this.sdk.session.prompt({
-          sessionID,
-          model: {
-            providerID: model.providerID,
-            modelID: model.modelID,
-          },
-          variant: this.sessionManager.getVariant(sessionID),
-          parts,
-          agent,
+  private async loadAvailableModes(directory: string): Promise<ModeOption[]> {
+    const agents = await this.config.sdk.app
+      .agents(
+        {
           directory,
-        })
-        const msg = response.data?.info
+        },
+        { throwOnError: true },
+      )
+      .then((resp) => resp.data!)
+
+    return agents
+      .filter((agent) => agent.mode !== "subagent" && !agent.hidden)
+      .map((agent) => ({
+        id: agent.name,
+        name: agent.name,
+        description: agent.description,
+      }))
+  }
 
-        await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
+  private async resolveModeState(
+    directory: string,
+    sessionId: string,
+  ): Promise<{ availableModes: ModeOption[]; currentModeId?: string }> {
+    const availableModes = await this.loadAvailableModes(directory)
+    const currentModeId =
+      this.sessionManager.get(sessionId).modeId ||
+      (await (async () => {
+        if (!availableModes.length) return undefined
+        const defaultAgentName = await AppRuntime.runPromise(AgentModule.Service.use((svc) => svc.defaultAgent()))
+        const resolvedModeId =
+          availableModes.find((mode) => mode.name === defaultAgentName)?.id ?? availableModes[0].id
+        this.sessionManager.setMode(sessionId, resolvedModeId)
+        return resolvedModeId
+      })())
+
+    return { availableModes, currentModeId }
+  }
 
-        return {
-          stopReason: "end_turn" as const,
-          usage: msg ? buildUsage(msg) : undefined,
-          _meta: {},
+  private async loadSessionMode(params: LoadSessionRequest) {
+    const directory = params.cwd
+    const model = await defaultModel(this.config, directory)
+    const sessionId = params.sessionId
+
+    const providers = await this.sdk.config.providers({ directory }).then((x) => x.data!.providers)
+    const entries = sortProvidersByName(providers)
+    const availableVariants = modelVariantsFromProviders(entries, model)
+    const currentVariant = this.sessionManager.getVariant(sessionId)
+    if (currentVariant && !availableVariants.includes(currentVariant)) {
+      this.sessionManager.setVariant(sessionId, undefined)
+    }
+    const availableModels = buildAvailableModels(entries, { includeVariants: true })
+    const modeState = await this.resolveModeState(directory, sessionId)
+    const currentModeId = modeState.currentModeId
+    const modes = currentModeId
+      ? {
+          availableModes: modeState.availableModes,
+          currentModeId,
         }
-      }
+      : undefined
 
-      const command = await this.config.sdk.command
-        .list({ directory }, { throwOnError: true })
-        .then((x) => x.data!.find((c) => c.name === cmd.name))
-      if (command) {
-        const response = await this.sdk.session.command({
-          sessionID,
-          command: command.name,
-          arguments: cmd.args,
-          model: model.providerID + "/" + model.modelID,
-          agent,
+    const commands = await this.config.sdk.command
+      .list(
+        {
           directory,
-        })
-        const msg = response.data?.info
-
-        await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
+        },
+        { throwOnError: true },
+      )
+      .then((resp) => resp.data!)
+
+    const availableCommands = commands.map((command) => ({
+      name: command.name,
+      description: command.description ?? "",
+    }))
+    const names = new Set(availableCommands.map((c) => c.name))
+    if (!names.has("compact"))
+      availableCommands.push({
+        name: "compact",
+        description: "compact the session",
+      })
 
-        return {
-          stopReason: "end_turn" as const,
-          usage: msg ? buildUsage(msg) : undefined,
-          _meta: {},
+    const mcpServers: Record<string, ConfigMCP.Info> = {}
+    for (const server of params.mcpServers) {
+      if ("type" in server) {
+        mcpServers[server.name] = {
+          url: server.url,
+          headers: server.headers.reduce<Record<string, string>>((acc, { name, value }) => {
+            acc[name] = value
+            return acc
+          }, {}),
+          type: "remote",
+        }
+      } else {
+        mcpServers[server.name] = {
+          type: "local",
+          command: [server.command, ...server.args],
+          environment: server.env.reduce<Record<string, string>>((acc, { name, value }) => {
+            acc[name] = value
+            return acc
+          }, {}),
         }
       }
+    }
 
-      switch (cmd.name) {
-        case "compact":
-          await this.config.sdk.session.summarize(
+    await Promise.all(
+      Object.entries(mcpServers).map(async ([key, mcp]) => {
+        await this.sdk.mcp
+          .add(
             {
-              sessionID,
               directory,
-              providerID: model.providerID,
-              modelID: model.modelID,
+              name: key,
+              config: mcp,
             },
             { throwOnError: true },
           )
-          break
-      }
-
-      await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
-
-      return {
-        stopReason: "end_turn" as const,
-        _meta: {},
-      }
-    }
+          .catch((error) => {
+            log.error("failed to add mcp server", { name: key, error })
+          })
+      }),
+    )
 
-    async cancel(params: CancelNotification) {
-      const session = this.sessionManager.get(params.sessionId)
-      await this.config.sdk.session.abort(
-        {
-          sessionID: params.sessionId,
-          directory: session.cwd,
+    setTimeout(() => {
+      void this.connection.sessionUpdate({
+        sessionId,
+        update: {
+          sessionUpdate: "available_commands_update",
+          availableCommands,
         },
-        { throwOnError: true },
-      )
+      })
+    }, 0)
+
+    return {
+      sessionId,
+      models: {
+        currentModelId: formatModelIdWithVariant(model, currentVariant, availableVariants, true),
+        availableModels,
+      },
+      modes,
+      configOptions: buildConfigOptions({
+        currentModelId: formatModelIdWithVariant(model, currentVariant, availableVariants, true),
+        availableModels,
+        modes,
+      }),
+      _meta: buildVariantMeta({
+        model,
+        variant: this.sessionManager.getVariant(sessionId),
+        availableVariants,
+      }),
     }
   }
 
-  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"
-
-      case "read":
-        return "read"
-
-      default:
-        return "other"
+  async unstable_setSessionModel(params: SetSessionModelRequest) {
+    const session = this.sessionManager.get(params.sessionId)
+    const providers = await this.sdk.config
+      .providers({ directory: session.cwd }, { throwOnError: true })
+      .then((x) => x.data!.providers)
+
+    const selection = parseModelSelection(params.modelId, providers)
+    this.sessionManager.setModel(session.id, selection.model)
+    this.sessionManager.setVariant(session.id, selection.variant)
+
+    const entries = sortProvidersByName(providers)
+    const availableVariants = modelVariantsFromProviders(entries, selection.model)
+
+    return {
+      _meta: buildVariantMeta({
+        model: selection.model,
+        variant: selection.variant,
+        availableVariants,
+      }),
     }
   }
 
-  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 []
-      default:
-        return []
+  async setSessionMode(params: SetSessionModeRequest): Promise<SetSessionModeResponse | void> {
+    const session = this.sessionManager.get(params.sessionId)
+    const availableModes = await this.loadAvailableModes(session.cwd)
+    if (!availableModes.some((mode) => mode.id === params.modeId)) {
+      throw new Error(`Agent not found: ${params.modeId}`)
     }
+    this.sessionManager.setMode(params.sessionId, params.modeId)
   }
 
-  async function defaultModel(config: ACPConfig, cwd?: string): Promise<{ providerID: ProviderID; modelID: ModelID }> {
-    const sdk = config.sdk
-    const configured = config.defaultModel
-    if (configured) return configured
+  async setSessionConfigOption(params: SetSessionConfigOptionRequest): Promise<SetSessionConfigOptionResponse> {
+    const session = this.sessionManager.get(params.sessionId)
+    const providers = await this.sdk.config
+      .providers({ directory: session.cwd }, { throwOnError: true })
+      .then((x) => x.data!.providers)
+    const entries = sortProvidersByName(providers)
 
-    const directory = cwd ?? process.cwd()
+    if (params.configId === "model") {
+      if (typeof params.value !== "string") throw RequestError.invalidParams("model value must be a string")
+      const selection = parseModelSelection(params.value, providers)
+      this.sessionManager.setModel(session.id, selection.model)
+      this.sessionManager.setVariant(session.id, selection.variant)
+    } else if (params.configId === "mode") {
+      if (typeof params.value !== "string") throw RequestError.invalidParams("mode value must be a string")
+      const availableModes = await this.loadAvailableModes(session.cwd)
+      if (!availableModes.some((mode) => mode.id === params.value)) {
+        throw RequestError.invalidParams(JSON.stringify({ error: `Mode not found: ${params.value}` }))
+      }
+      this.sessionManager.setMode(session.id, params.value)
+    } else {
+      throw RequestError.invalidParams(JSON.stringify({ error: `Unknown config option: ${params.configId}` }))
+    }
 
-    const specified = await sdk.config
-      .get({ directory }, { throwOnError: true })
-      .then((resp) => {
-        const cfg = resp.data
-        if (!cfg || !cfg.model) return undefined
-        return Provider.parseModel(cfg.model)
-      })
-      .catch((error) => {
-        log.error("failed to load user config for default model", { error })
-        return undefined
-      })
+    const updatedSession = this.sessionManager.get(session.id)
+    const model = updatedSession.model ?? (await defaultModel(this.config, session.cwd))
+    const availableVariants = modelVariantsFromProviders(entries, model)
+    const currentModelId = formatModelIdWithVariant(model, updatedSession.variant, availableVariants, true)
+    const availableModels = buildAvailableModels(entries, { includeVariants: true })
+    const modeState = await this.resolveModeState(session.cwd, session.id)
+    const modes = modeState.currentModeId
+      ? { availableModes: modeState.availableModes, currentModeId: modeState.currentModeId }
+      : undefined
 
-    const providers = await sdk.config
-      .providers({ directory }, { throwOnError: true })
-      .then((x) => x.data?.providers ?? [])
-      .catch((error) => {
-        log.error("failed to list providers for default model", { error })
-        return []
-      })
+    return {
+      configOptions: buildConfigOptions({ currentModelId, availableModels, modes }),
+    }
+  }
 
-    if (specified && providers.length) {
-      const provider = providers.find((p) => p.id === specified.providerID)
-      if (provider && provider.models[specified.modelID]) return specified
+  async prompt(params: PromptRequest) {
+    const sessionID = params.sessionId
+    const session = this.sessionManager.get(sessionID)
+    const directory = session.cwd
+
+    const current = session.model
+    const model = current ?? (await defaultModel(this.config, directory))
+    if (!current) {
+      this.sessionManager.setModel(session.id, model)
     }
+    const agent =
+      session.modeId ?? (await AppRuntime.runPromise(AgentModule.Service.use((svc) => svc.defaultAgent())))
+
+    const parts: Array<
+      | { type: "text"; text: string; synthetic?: boolean; ignored?: boolean }
+      | { type: "file"; url: string; filename: string; mime: string }
+    > = []
+    for (const part of params.prompt) {
+      switch (part.type) {
+        case "text":
+          const audience = part.annotations?.audience
+          const forAssistant = audience?.length === 1 && audience[0] === "assistant"
+          const forUser = audience?.length === 1 && audience[0] === "user"
+          parts.push({
+            type: "text" as const,
+            text: part.text,
+            ...(forAssistant && { synthetic: true }),
+            ...(forUser && { ignored: true }),
+          })
+          break
+        case "image": {
+          const parsed = parseUri(part.uri ?? "")
+          const filename = parsed.type === "file" ? parsed.filename : "image"
+          if (part.data) {
+            parts.push({
+              type: "file",
+              url: `data:${part.mimeType};base64,${part.data}`,
+              filename,
+              mime: part.mimeType,
+            })
+          } else if (part.uri && part.uri.startsWith("http:")) {
+            parts.push({
+              type: "file",
+              url: part.uri,
+              filename,
+              mime: part.mimeType,
+            })
+          }
+          break
+        }
 
-    if (specified && !providers.length) return specified
+        case "resource_link":
+          const parsed = parseUri(part.uri)
+          // Use the name from resource_link if available
+          if (part.name && parsed.type === "file") {
+            parsed.filename = part.name
+          }
+          parts.push(parsed)
 
-    const opencodeProvider = providers.find((p) => p.id === "opencode")
-    if (opencodeProvider) {
-      if (opencodeProvider.models["big-pickle"]) {
-        return { providerID: ProviderID.opencode, modelID: ModelID.make("big-pickle") }
-      }
-      const [best] = Provider.sort(Object.values(opencodeProvider.models))
-      if (best) {
-        return {
-          providerID: ProviderID.make(best.providerID),
-          modelID: ModelID.make(best.id),
+          break
+
+        case "resource": {
+          const resource = part.resource
+          if ("text" in resource && resource.text) {
+            parts.push({
+              type: "text",
+              text: resource.text,
+            })
+          } else if ("blob" in resource && resource.blob && resource.mimeType) {
+            // Binary resource (PDFs, etc.): store as file part with data URL
+            const parsed = parseUri(resource.uri ?? "")
+            const filename = parsed.type === "file" ? parsed.filename : "file"
+            parts.push({
+              type: "file",
+              url: `data:${resource.mimeType};base64,${resource.blob}`,
+              filename,
+              mime: resource.mimeType,
+            })
+          }
+          break
         }
+
+        default:
+          break
       }
     }
 
-    const models = providers.flatMap((p) => Object.values(p.models))
-    const [best] = Provider.sort(models)
-    if (best) {
+    log.info("parts", { parts })
+
+    const cmd = (() => {
+      const text = parts
+        .filter((p): p is { type: "text"; text: string } => p.type === "text")
+        .map((p) => p.text)
+        .join("")
+        .trim()
+
+      if (!text.startsWith("/")) return
+
+      const [name, ...rest] = text.slice(1).split(/\s+/)
+      return { name, args: rest.join(" ").trim() }
+    })()
+
+    const buildUsage = (msg: AssistantMessage): Usage => ({
+      totalTokens:
+        msg.tokens.input +
+        msg.tokens.output +
+        msg.tokens.reasoning +
+        (msg.tokens.cache?.read ?? 0) +
+        (msg.tokens.cache?.write ?? 0),
+      inputTokens: msg.tokens.input,
+      outputTokens: msg.tokens.output,
+      thoughtTokens: msg.tokens.reasoning || undefined,
+      cachedReadTokens: msg.tokens.cache?.read || undefined,
+      cachedWriteTokens: msg.tokens.cache?.write || undefined,
+    })
+
+    if (!cmd) {
+      const response = await this.sdk.session.prompt({
+        sessionID,
+        model: {
+          providerID: model.providerID,
+          modelID: model.modelID,
+        },
+        variant: this.sessionManager.getVariant(sessionID),
+        parts,
+        agent,
+        directory,
+      })
+      const msg = response.data?.info
+
+      await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
+
       return {
-        providerID: ProviderID.make(best.providerID),
-        modelID: ModelID.make(best.id),
+        stopReason: "end_turn" as const,
+        usage: msg ? buildUsage(msg) : undefined,
+        _meta: {},
       }
     }
 
-    if (specified) return specified
+    const command = await this.config.sdk.command
+      .list({ directory }, { throwOnError: true })
+      .then((x) => x.data!.find((c) => c.name === cmd.name))
+    if (command) {
+      const response = await this.sdk.session.command({
+        sessionID,
+        command: command.name,
+        arguments: cmd.args,
+        model: model.providerID + "/" + model.modelID,
+        agent,
+        directory,
+      })
+      const msg = response.data?.info
 
-    return { providerID: ProviderID.opencode, modelID: ModelID.make("big-pickle") }
-  }
+      await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
 
-  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: "file",
-          url: uri,
-          filename: name,
-          mime: "text/plain",
-        }
-      }
-      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: pathToFileURL(path).href,
-            filename: name,
-            mime: "text/plain",
-          }
-        }
-      }
       return {
-        type: "text",
-        text: uri,
-      }
-    } catch {
-      return {
-        type: "text",
-        text: uri,
+        stopReason: "end_turn" as const,
+        usage: msg ? buildUsage(msg) : undefined,
+        _meta: {},
       }
     }
-  }
 
-  function getNewContent(fileOriginal: string, unifiedDiff: string): string | undefined {
-    const result = applyPatch(fileOriginal, unifiedDiff)
-    if (result === false) {
-      log.error("Failed to apply unified diff (context mismatch)")
-      return undefined
+    switch (cmd.name) {
+      case "compact":
+        await this.config.sdk.session.summarize(
+          {
+            sessionID,
+            directory,
+            providerID: model.providerID,
+            modelID: model.modelID,
+          },
+          { throwOnError: true },
+        )
+        break
+    }
+
+    await sendUsageUpdate(this.connection, this.sdk, sessionID, directory)
+
+    return {
+      stopReason: "end_turn" as const,
+      _meta: {},
     }
-    return result
   }
 
-  function sortProvidersByName<T extends { name: string }>(providers: T[]): T[] {
-    return [...providers].sort((a, b) => {
-      const nameA = a.name.toLowerCase()
-      const nameB = b.name.toLowerCase()
-      if (nameA < nameB) return -1
-      if (nameA > nameB) return 1
-      return 0
-    })
+  async cancel(params: CancelNotification) {
+    const session = this.sessionManager.get(params.sessionId)
+    await this.config.sdk.session.abort(
+      {
+        sessionID: params.sessionId,
+        directory: session.cwd,
+      },
+      { throwOnError: true },
+    )
   }
+}
 
-  function modelVariantsFromProviders(
-    providers: Array<{ id: string; models: Record<string, { variants?: Record<string, any> }> }>,
-    model: { providerID: ProviderID; modelID: ModelID },
-  ): string[] {
-    const provider = providers.find((entry) => entry.id === model.providerID)
-    if (!provider) return []
-    const modelInfo = provider.models[model.modelID]
-    if (!modelInfo?.variants) return []
-    return Object.keys(modelInfo.variants)
+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"
+
+    case "read":
+      return "read"
+
+    default:
+      return "other"
   }
+}
 
-  function buildAvailableModels(
-    providers: Array<{ id: string; name: string; models: Record<string, any> }>,
-    options: { includeVariants?: boolean } = {},
-  ): ModelOption[] {
-    const includeVariants = options.includeVariants ?? false
-    return providers.flatMap((provider) => {
-      const unsorted: Array<{ id: string; name: string; variants?: Record<string, any> }> = Object.values(
-        provider.models,
-      )
-      const models = Provider.sort(unsorted)
-      return models.flatMap((model) => {
-        const base: ModelOption = {
-          modelId: `${provider.id}/${model.id}`,
-          name: `${provider.name}/${model.name}`,
-        }
-        if (!includeVariants || !model.variants) return [base]
-        const variants = Object.keys(model.variants).filter((variant) => variant !== DEFAULT_VARIANT_VALUE)
-        const variantOptions = variants.map((variant) => ({
-          modelId: `${provider.id}/${model.id}/${variant}`,
-          name: `${provider.name}/${model.name} (${variant})`,
-        }))
-        return [base, ...variantOptions]
-      })
+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 []
+    default:
+      return []
+  }
+}
+
+async function defaultModel(config: ACPConfig, cwd?: string): Promise<{ providerID: ProviderID; modelID: ModelID }> {
+  const sdk = config.sdk
+  const configured = config.defaultModel
+  if (configured) return configured
+
+  const directory = cwd ?? process.cwd()
+
+  const specified = await sdk.config
+    .get({ directory }, { throwOnError: true })
+    .then((resp) => {
+      const cfg = resp.data
+      if (!cfg || !cfg.model) return undefined
+      return Provider.parseModel(cfg.model)
+    })
+    .catch((error) => {
+      log.error("failed to load user config for default model", { error })
+      return undefined
     })
+
+  const providers = await sdk.config
+    .providers({ directory }, { throwOnError: true })
+    .then((x) => x.data?.providers ?? [])
+    .catch((error) => {
+      log.error("failed to list providers for default model", { error })
+      return []
+    })
+
+  if (specified && providers.length) {
+    const provider = providers.find((p) => p.id === specified.providerID)
+    if (provider && provider.models[specified.modelID]) return specified
   }
 
-  function formatModelIdWithVariant(
-    model: { providerID: ProviderID; modelID: ModelID },
-    variant: string | undefined,
-    availableVariants: string[],
-    includeVariant: boolean,
-  ) {
-    const base = `${model.providerID}/${model.modelID}`
-    if (!includeVariant || !variant || !availableVariants.includes(variant)) return base
-    return `${base}/${variant}`
+  if (specified && !providers.length) return specified
+
+  const opencodeProvider = providers.find((p) => p.id === "opencode")
+  if (opencodeProvider) {
+    if (opencodeProvider.models["big-pickle"]) {
+      return { providerID: ProviderID.opencode, modelID: ModelID.make("big-pickle") }
+    }
+    const [best] = Provider.sort(Object.values(opencodeProvider.models))
+    if (best) {
+      return {
+        providerID: ProviderID.make(best.providerID),
+        modelID: ModelID.make(best.id),
+      }
+    }
   }
 
-  function buildVariantMeta(input: {
-    model: { providerID: ProviderID; modelID: ModelID }
-    variant?: string
-    availableVariants: string[]
-  }) {
+  const models = providers.flatMap((p) => Object.values(p.models))
+  const [best] = Provider.sort(models)
+  if (best) {
     return {
-      opencode: {
-        modelId: `${input.model.providerID}/${input.model.modelID}`,
-        variant: input.variant ?? null,
-        availableVariants: input.availableVariants,
-      },
+      providerID: ProviderID.make(best.providerID),
+      modelID: ModelID.make(best.id),
     }
   }
 
-  function parseModelSelection(
-    modelId: string,
-    providers: Array<{ id: string; models: Record<string, { variants?: Record<string, any> }> }>,
-  ): { model: { providerID: ProviderID; modelID: ModelID }; variant?: string } {
-    const parsed = Provider.parseModel(modelId)
-    const provider = providers.find((p) => p.id === parsed.providerID)
-    if (!provider) {
-      return { model: parsed, variant: undefined }
-    }
+  if (specified) return specified
 
-    // Check if modelID exists directly
-    if (provider.models[parsed.modelID]) {
-      return { model: parsed, variant: undefined }
-    }
+  return { providerID: ProviderID.opencode, modelID: ModelID.make("big-pickle") }
+}
 
-    // Try to extract variant from end of modelID (e.g., "claude-sonnet-4/high" -> model: "claude-sonnet-4", variant: "high")
-    const segments = parsed.modelID.split("/")
-    if (segments.length > 1) {
-      const candidateVariant = segments[segments.length - 1]
-      const baseModelId = segments.slice(0, -1).join("/")
-      const baseModelInfo = provider.models[baseModelId]
-      if (baseModelInfo?.variants && candidateVariant in baseModelInfo.variants) {
+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: "file",
+        url: uri,
+        filename: name,
+        mime: "text/plain",
+      }
+    }
+    if (uri.startsWith("zed://")) {
+      const url = new URL(uri)
+      const path = url.searchParams.get("path")
+      if (path) {
+        const name = path.split("/").pop() || path
         return {
-          model: { providerID: parsed.providerID, modelID: ModelID.make(baseModelId) },
-          variant: candidateVariant,
+          type: "file",
+          url: pathToFileURL(path).href,
+          filename: name,
+          mime: "text/plain",
         }
       }
     }
+    return {
+      type: "text",
+      text: uri,
+    }
+  } catch {
+    return {
+      type: "text",
+      text: uri,
+    }
+  }
+}
+
+function getNewContent(fileOriginal: string, unifiedDiff: string): string | undefined {
+  const result = applyPatch(fileOriginal, unifiedDiff)
+  if (result === false) {
+    log.error("Failed to apply unified diff (context mismatch)")
+    return undefined
+  }
+  return result
+}
+
+function sortProvidersByName<T extends { name: string }>(providers: T[]): T[] {
+  return [...providers].sort((a, b) => {
+    const nameA = a.name.toLowerCase()
+    const nameB = b.name.toLowerCase()
+    if (nameA < nameB) return -1
+    if (nameA > nameB) return 1
+    return 0
+  })
+}
+
+function modelVariantsFromProviders(
+  providers: Array<{ id: string; models: Record<string, { variants?: Record<string, any> }> }>,
+  model: { providerID: ProviderID; modelID: ModelID },
+): string[] {
+  const provider = providers.find((entry) => entry.id === model.providerID)
+  if (!provider) return []
+  const modelInfo = provider.models[model.modelID]
+  if (!modelInfo?.variants) return []
+  return Object.keys(modelInfo.variants)
+}
+
+function buildAvailableModels(
+  providers: Array<{ id: string; name: string; models: Record<string, any> }>,
+  options: { includeVariants?: boolean } = {},
+): ModelOption[] {
+  const includeVariants = options.includeVariants ?? false
+  return providers.flatMap((provider) => {
+    const unsorted: Array<{ id: string; name: string; variants?: Record<string, any> }> = Object.values(
+      provider.models,
+    )
+    const models = Provider.sort(unsorted)
+    return models.flatMap((model) => {
+      const base: ModelOption = {
+        modelId: `${provider.id}/${model.id}`,
+        name: `${provider.name}/${model.name}`,
+      }
+      if (!includeVariants || !model.variants) return [base]
+      const variants = Object.keys(model.variants).filter((variant) => variant !== DEFAULT_VARIANT_VALUE)
+      const variantOptions = variants.map((variant) => ({
+        modelId: `${provider.id}/${model.id}/${variant}`,
+        name: `${provider.name}/${model.name} (${variant})`,
+      }))
+      return [base, ...variantOptions]
+    })
+  })
+}
+
+function formatModelIdWithVariant(
+  model: { providerID: ProviderID; modelID: ModelID },
+  variant: string | undefined,
+  availableVariants: string[],
+  includeVariant: boolean,
+) {
+  const base = `${model.providerID}/${model.modelID}`
+  if (!includeVariant || !variant || !availableVariants.includes(variant)) return base
+  return `${base}/${variant}`
+}
+
+function buildVariantMeta(input: {
+  model: { providerID: ProviderID; modelID: ModelID }
+  variant?: string
+  availableVariants: string[]
+}) {
+  return {
+    opencode: {
+      modelId: `${input.model.providerID}/${input.model.modelID}`,
+      variant: input.variant ?? null,
+      availableVariants: input.availableVariants,
+    },
+  }
+}
 
+function parseModelSelection(
+  modelId: string,
+  providers: Array<{ id: string; models: Record<string, { variants?: Record<string, any> }> }>,
+): { model: { providerID: ProviderID; modelID: ModelID }; variant?: string } {
+  const parsed = Provider.parseModel(modelId)
+  const provider = providers.find((p) => p.id === parsed.providerID)
+  if (!provider) {
     return { model: parsed, variant: undefined }
   }
 
-  function buildConfigOptions(input: {
-    currentModelId: string
-    availableModels: ModelOption[]
-    modes?: { availableModes: ModeOption[]; currentModeId: string } | undefined
-  }): SessionConfigOption[] {
-    const options: SessionConfigOption[] = [
-      {
-        id: "model",
-        name: "Model",
-        category: "model",
-        type: "select",
-        currentValue: input.currentModelId,
-        options: input.availableModels.map((m) => ({ value: m.modelId, name: m.name })),
-      },
-    ]
-    if (input.modes) {
-      options.push({
-        id: "mode",
-        name: "Session Mode",
-        category: "mode",
-        type: "select",
-        currentValue: input.modes.currentModeId,
-        options: input.modes.availableModes.map((m) => ({
-          value: m.id,
-          name: m.name,
-          ...(m.description ? { description: m.description } : {}),
-        })),
-      })
+  // Check if modelID exists directly
+  if (provider.models[parsed.modelID]) {
+    return { model: parsed, variant: undefined }
+  }
+
+  // Try to extract variant from end of modelID (e.g., "claude-sonnet-4/high" -> model: "claude-sonnet-4", variant: "high")
+  const segments = parsed.modelID.split("/")
+  if (segments.length > 1) {
+    const candidateVariant = segments[segments.length - 1]
+    const baseModelId = segments.slice(0, -1).join("/")
+    const baseModelInfo = provider.models[baseModelId]
+    if (baseModelInfo?.variants && candidateVariant in baseModelInfo.variants) {
+      return {
+        model: { providerID: parsed.providerID, modelID: ModelID.make(baseModelId) },
+        variant: candidateVariant,
+      }
     }
-    return options
   }
+
+  return { model: parsed, variant: undefined }
+}
+
+function buildConfigOptions(input: {
+  currentModelId: string
+  availableModels: ModelOption[]
+  modes?: { availableModes: ModeOption[]; currentModeId: string } | undefined
+}): SessionConfigOption[] {
+  const options: SessionConfigOption[] = [
+    {
+      id: "model",
+      name: "Model",
+      category: "model",
+      type: "select",
+      currentValue: input.currentModelId,
+      options: input.availableModels.map((m) => ({ value: m.modelId, name: m.name })),
+    },
+  ]
+  if (input.modes) {
+    options.push({
+      id: "mode",
+      name: "Session Mode",
+      category: "mode",
+      type: "select",
+      currentValue: input.modes.currentModeId,
+      options: input.modes.availableModes.map((m) => ({
+        value: m.id,
+        name: m.name,
+        ...(m.description ? { description: m.description } : {}),
+      })),
+    })
+  }
+  return options
 }
+
+export * as ACP from "./agent"