feat(v2): add session message model conversion

packages/opencode/src/cli/cmd/tui/context/sync-v2.tsx

@@ -143,6 +143,15 @@ export const { use: useSyncV2, provider: SyncProviderV2 } = createSimpleContext(
               currentAssistant.snapshot = { ...currentAssistant.snapshot, end: event.properties.snapshot }
           })
           break
+        case "session.next.step.failed":
+          update(event.properties.sessionID, (draft) => {
+            const currentAssistant = activeAssistant(draft)
+            if (!currentAssistant) return
+            currentAssistant.time.completed = event.properties.timestamp
+            currentAssistant.finish = "error"
+            currentAssistant.error = event.properties.error
+          })
+          break
         case "session.next.text.started":
           update(event.properties.sessionID, (draft) => {
             activeAssistant(draft)?.content.push({ type: "text", text: "" })
@@ -210,7 +219,7 @@ export const { use: useSyncV2, provider: SyncProviderV2 } = createSimpleContext(
             match.time.completed = event.properties.timestamp
           })
           break
-        case "session.next.tool.error":
+        case "session.next.tool.failed":
           update(event.properties.sessionID, (draft) => {
             const match = latestTool(activeAssistant(draft), event.properties.callID)
             if (match?.state.status !== "running") return

packages/opencode/src/session/processor.ts

@@ -405,7 +405,7 @@ export const layer: Layer.Layer<
           case "tool-error": {
             const toolCall = yield* readToolCall(value.toolCallId)
             // TODO(v2): Temporary dual-write while migrating session messages to v2 events.
-            EventV2.run(SessionEvent.Tool.Error.Sync, {
+            EventV2.run(SessionEvent.Tool.Failed.Sync, {
               sessionID: ctx.sessionID,
               callID: value.toolCallId,
               error: {
@@ -650,6 +650,17 @@ export const layer: Layer.Layer<
           yield* bus.publish(Session.Event.Error, { sessionID: ctx.sessionID, error })
           return
         }
+        if (!ctx.assistantMessage.summary) {
+          // TODO(v2): Temporary dual-write while migrating session messages to v2 events.
+          EventV2.run(SessionEvent.Step.Failed.Sync, {
+            sessionID: ctx.sessionID,
+            error: {
+              type: error.name,
+              message: errorMessage(e),
+            },
+            timestamp: DateTime.makeUnsafe(Date.now()),
+          })
+        }
         ctx.assistantMessage.error = error
         yield* bus.publish(Session.Event.Error, {
           sessionID: ctx.assistantMessage.sessionID,

packages/opencode/src/session/projectors-next.ts

@@ -161,6 +161,9 @@ export default [
   SyncEvent.project(SessionEvent.Step.Ended.Sync, (db, data, event) => {
     update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.step.ended", data })
   }),
+  SyncEvent.project(SessionEvent.Step.Failed.Sync, (db, data, event) => {
+    update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.step.failed", data })
+  }),
   SyncEvent.project(SessionEvent.Text.Started.Sync, (db, data, event) => {
     update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.text.started", data })
   }),
@@ -181,8 +184,8 @@ export default [
   SyncEvent.project(SessionEvent.Tool.Success.Sync, (db, data, event) => {
     update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.tool.success", data })
   }),
-  SyncEvent.project(SessionEvent.Tool.Error.Sync, (db, data, event) => {
-    update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.tool.error", data })
+  SyncEvent.project(SessionEvent.Tool.Failed.Sync, (db, data, event) => {
+    update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.tool.failed", data })
   }),
   SyncEvent.project(SessionEvent.Reasoning.Started.Sync, (db, data, event) => {
     update(db, { id: SessionMessage.ID.make(event.id), type: "session.next.reasoning.started", data })

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

@@ -22,6 +22,11 @@ const Base = {
   sessionID: SessionID,
 }
 
+const Error = Schema.Struct({
+  type: Schema.String,
+  message: Schema.String,
+})
+
 export const AgentSwitched = EventV2.define({
   type: "session.next.agent.switched",
   aggregate: "sessionID",
@@ -128,6 +133,16 @@ export namespace Step {
     },
   })
   export type Ended = Schema.Schema.Type<typeof Ended>
+
+  export const Failed = EventV2.define({
+    type: "session.next.step.failed",
+    aggregate: "sessionID",
+    schema: {
+      ...Base,
+      error: Error,
+    },
+  })
+  export type Failed = Schema.Schema.Type<typeof Failed>
 }
 
 export namespace Text {
@@ -275,23 +290,20 @@ export namespace Tool {
   })
   export type Success = Schema.Schema.Type<typeof Success>
 
-  export const Error = EventV2.define({
-    type: "session.next.tool.error",
+  export const Failed = EventV2.define({
+    type: "session.next.tool.failed",
     aggregate: "sessionID",
     schema: {
       ...Base,
       callID: Schema.String,
-      error: Schema.Struct({
-        type: Schema.String,
-        message: Schema.String,
-      }),
+      error: Error,
       provider: Schema.Struct({
         executed: Schema.Boolean,
         metadata: Schema.Record(Schema.String, Schema.Unknown).pipe(Schema.optional),
       }),
     },
   })
-  export type Error = Schema.Schema.Type<typeof Error>
+  export type Failed = Schema.Schema.Type<typeof Failed>
 }
 
 export const RetryError = Schema.Struct({
@@ -359,6 +371,7 @@ export const All = Schema.Union(
     Shell.Ended,
     Step.Started,
     Step.Ended,
+    Step.Failed,
     Text.Started,
     Text.Delta,
     Text.Ended,
@@ -368,7 +381,7 @@ export const All = Schema.Union(
     Tool.Called,
     Tool.Progress,
     Tool.Success,
-    Tool.Error,
+    Tool.Failed,
     Reasoning.Started,
     Reasoning.Delta,
     Reasoning.Ended,

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

@@ -0,0 +1,285 @@
+import { isMedia } from "@/util/media"
+import type { Provider } from "@/provider/provider"
+import { Effect } from "effect"
+import { convertToModelMessages, type ModelMessage, type ProviderMetadata, type UIMessage } from "ai"
+import * as EffectLogger from "@opencode-ai/core/effect/logger"
+import { SessionMessage } from "./session-message"
+import { ID } from "./event"
+
+export const SYNTHETIC_ATTACHMENT_PROMPT = "Attached image(s) from tool result:"
+
+type Attachment = {
+  mime: string
+  url: string
+  filename?: string
+}
+
+type JsonValue = null | boolean | number | string | JsonValue[] | { [key: string]: JsonValue | undefined }
+
+function truncateToolOutput(text: string, maxChars?: number) {
+  if (!maxChars || text.length <= maxChars) return text
+  const omitted = text.length - maxChars
+  return `${text.slice(0, maxChars)}\n[Tool output truncated for compaction: omitted ${omitted} chars]`
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null
+}
+
+function isJsonValue(value: unknown): value is JsonValue {
+  if (value === null) return true
+  if (typeof value === "boolean" || typeof value === "number" || typeof value === "string") return true
+  if (Array.isArray(value)) return value.every(isJsonValue)
+  if (isRecord(value)) return Object.values(value).every((item) => item === undefined || isJsonValue(item))
+  return false
+}
+
+function outputText(content: SessionMessage.ToolStateCompleted["content"]) {
+  return content
+    .filter((item) => item.type === "text")
+    .map((item) => item.text)
+    .join("\n")
+}
+
+function outputAttachments(content: SessionMessage.ToolStateCompleted["content"]) {
+  return content
+    .filter((item) => item.type === "file")
+    .map((item) => ({
+      mime: item.mime,
+      url: item.uri,
+      filename: item.name,
+    }))
+}
+
+function providerMeta(metadata: Record<string, unknown> | undefined) {
+  if (!metadata) return undefined
+  const result: ProviderMetadata = Object.fromEntries(
+    Object.entries(metadata)
+      .filter(([key]) => key !== "providerExecuted")
+      .filter(
+        (entry): entry is [string, Record<string, JsonValue | undefined>] =>
+          isRecord(entry[1]) && Object.values(entry[1]).every((item) => item === undefined || isJsonValue(item)),
+      ),
+  )
+  return Object.keys(result).length > 0 ? result : undefined
+}
+
+function toModelOutput(options: { output: unknown }) {
+  if (typeof options.output === "string") return { type: "text", value: options.output }
+  if (!isRecord(options.output)) return { type: "json", value: options.output as never }
+
+  const attachments = Array.isArray(options.output.attachments)
+    ? options.output.attachments.filter(
+        (attachment): attachment is Attachment =>
+          isRecord(attachment) && typeof attachment.mime === "string" && typeof attachment.url === "string",
+      )
+    : []
+  const text = typeof options.output.text === "string" ? options.output.text : ""
+
+  return {
+    type: "content",
+    value: [
+      ...(text ? [{ type: "text" as const, text }] : []),
+      ...attachments
+        .filter((attachment) => attachment.url.startsWith("data:") && attachment.url.includes(","))
+        .map((attachment) => ({
+          type: "media" as const,
+          mediaType: attachment.mime,
+          data: attachment.url.slice(attachment.url.indexOf(",") + 1),
+        })),
+    ],
+  }
+}
+
+function supportsMediaInToolResults(model: Provider.Model) {
+  if (model.api.npm === "@ai-sdk/anthropic") return true
+  if (model.api.npm === "@ai-sdk/openai") return true
+  if (model.api.npm === "@ai-sdk/amazon-bedrock") return true
+  if (model.api.npm === "@ai-sdk/google-vertex/anthropic") return true
+  if (model.api.npm === "@ai-sdk/google") return model.api.id.toLowerCase().includes("gemini-3")
+  return false
+}
+
+export const toModelMessagesEffect = Effect.fnUntraced(function* (
+  input: SessionMessage.Message[],
+  model: Provider.Model,
+  options?: { stripMedia?: boolean; toolOutputMaxChars?: number },
+) {
+  const result: UIMessage[] = []
+  const toolNames = new Set<string>()
+  const supportsMedia = supportsMediaInToolResults(model)
+
+  for (const msg of input) {
+    if (msg.type === "user") {
+      const parts: UIMessage["parts"] = []
+      if (msg.text)
+        parts.push({
+          type: "text",
+          text: msg.text,
+        })
+      for (const file of msg.files ?? []) {
+        if (file.mime === "text/plain" || file.mime === "application/x-directory") continue
+        if (options?.stripMedia && isMedia(file.mime)) {
+          parts.push({
+            type: "text",
+            text: `[Attached ${file.mime}: ${file.name ?? "file"}]`,
+          })
+          continue
+        }
+        parts.push({
+          type: "file",
+          url: file.uri,
+          mediaType: file.mime,
+          filename: file.name,
+        })
+      }
+      if (parts.length > 0) result.push({ id: msg.id, role: "user", parts })
+    }
+
+    if (msg.type === "synthetic" && msg.text) {
+      result.push({
+        id: msg.id,
+        role: "user",
+        parts: [{ type: "text", text: msg.text }],
+      })
+    }
+
+    if (msg.type === "shell") {
+      result.push({
+        id: msg.id,
+        role: "user",
+        parts: [
+          {
+            type: "text",
+            text: `The following shell command was executed by the user:\n\n${msg.command}${
+              msg.output ? `\n\nOutput:\n${msg.output}` : ""
+            }`,
+          },
+        ],
+      })
+    }
+
+    if (msg.type === "compaction" && msg.summary) {
+      result.push({
+        id: `${msg.id}-summary`,
+        role: "assistant",
+        parts: [{ type: "text", text: msg.summary }],
+      })
+    }
+
+    if (msg.type === "assistant") {
+      const differentModel = `${model.providerID}/${model.id}` !== `${msg.model.providerID}/${msg.model.id}`
+      if (msg.error && !msg.content.some((item) => item.type === "text" || item.type === "tool")) continue
+
+      const parts: UIMessage["parts"] = []
+      const media: Attachment[] = []
+      for (const content of msg.content) {
+        if (content.type === "text") {
+          parts.push({ type: "text", text: content.text })
+          continue
+        }
+        if (content.type === "reasoning") {
+          if (differentModel) {
+            if (content.text.trim().length > 0) parts.push({ type: "text", text: content.text })
+            continue
+          }
+          parts.push({ type: "reasoning", text: content.text })
+          continue
+        }
+
+        toolNames.add(content.name)
+        if (content.state.status === "completed") {
+          const output = content.time.pruned
+            ? "[Old tool result content cleared]"
+            : truncateToolOutput(outputText(content.state.content), options?.toolOutputMaxChars)
+          const attachments =
+            content.time.pruned || options?.stripMedia
+              ? []
+              : [
+                  ...outputAttachments(content.state.content),
+                  ...(content.state.attachments ?? []).map((attachment) => ({
+                    mime: attachment.mime,
+                    url: attachment.uri,
+                    filename: attachment.name,
+                  })),
+                ]
+          const mediaAttachments = attachments.filter((attachment) => isMedia(attachment.mime))
+          if (!supportsMedia && mediaAttachments.length > 0) media.push(...mediaAttachments)
+          const finalAttachments = supportsMedia
+            ? attachments
+            : attachments.filter((attachment) => !isMedia(attachment.mime))
+
+          parts.push({
+            type: `tool-${content.name}` as `tool-${string}`,
+            state: "output-available",
+            toolCallId: content.id,
+            input: content.state.input,
+            output: finalAttachments.length > 0 ? { text: output, attachments: finalAttachments } : output,
+            ...(content.provider?.executed ? { providerExecuted: true } : {}),
+            ...(differentModel ? {} : { callProviderMetadata: providerMeta(content.provider?.metadata) }),
+          })
+          continue
+        }
+
+        if (content.state.status === "error") {
+          parts.push({
+            type: `tool-${content.name}` as `tool-${string}`,
+            state: "output-error",
+            toolCallId: content.id,
+            input: content.state.input,
+            errorText: content.state.error.message,
+            ...(content.provider?.executed ? { providerExecuted: true } : {}),
+            ...(differentModel ? {} : { callProviderMetadata: providerMeta(content.provider?.metadata) }),
+          })
+          continue
+        }
+
+        parts.push({
+          type: `tool-${content.name}` as `tool-${string}`,
+          state: "output-error",
+          toolCallId: content.id,
+          input: content.state.status === "pending" ? {} : content.state.input,
+          errorText: "[Tool execution was interrupted]",
+          ...(content.provider?.executed ? { providerExecuted: true } : {}),
+          ...(differentModel ? {} : { callProviderMetadata: providerMeta(content.provider?.metadata) }),
+        })
+      }
+
+      if (parts.length > 0) {
+        result.push({ id: msg.id, role: "assistant", parts })
+        if (media.length > 0) {
+          result.push({
+            id: ID.create(),
+            role: "user",
+            parts: [
+              { type: "text", text: SYNTHETIC_ATTACHMENT_PROMPT },
+              ...media.map((attachment) => ({
+                type: "file" as const,
+                url: attachment.url,
+                mediaType: attachment.mime,
+                filename: attachment.filename,
+              })),
+            ],
+          })
+        }
+      }
+    }
+  }
+
+  return yield* Effect.promise(() =>
+    convertToModelMessages(result, {
+      // @ts-expect-error convertToModelMessages only needs tools[name]?.toModelOutput here.
+      tools: Object.fromEntries(Array.from(toolNames).map((toolName) => [toolName, { toModelOutput }])),
+    }),
+  )
+})
+
+export function toModelMessages(
+  input: SessionMessage.Message[],
+  model: Provider.Model,
+  options?: { stripMedia?: boolean; toolOutputMaxChars?: number },
+): Promise<ModelMessage[]> {
+  return Effect.runPromise(toModelMessagesEffect(input, model, options).pipe(Effect.provide(EffectLogger.layer)))
+}
+
+export * as SessionMessageModel from "./session-message-model"

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

@@ -199,6 +199,17 @@ export function update<Result>(adapter: Adapter<Result>, event: SessionEvent.Eve
         )
       }
     },
+    "session.next.step.failed": (event) => {
+      if (currentAssistant) {
+        adapter.updateAssistant(
+          produce(currentAssistant, (draft) => {
+            draft.time.completed = event.data.timestamp
+            draft.finish = "error"
+            draft.error = event.data.error
+          }),
+        )
+      }
+    },
     "session.next.text.started": () => {
       if (currentAssistant) {
         adapter.updateAssistant(
@@ -314,7 +325,7 @@ export function update<Result>(adapter: Adapter<Result>, event: SessionEvent.Eve
         )
       }
     },
-    "session.next.tool.error": (event) => {
+    "session.next.tool.failed": (event) => {
       if (currentAssistant) {
         adapter.updateAssistant(
           produce(currentAssistant, (draft) => {

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

@@ -152,7 +152,7 @@ export class Assistant extends Schema.Class<Assistant>("Session.Message.Assistan
       write: Schema.Finite,
     }),
   }).pipe(Schema.optional),
-  error: Schema.String.pipe(Schema.optional),
+  error: SessionEvent.Step.Failed.fields.data.fields.error.pipe(Schema.optional),
   time: Schema.Struct({
     created: V2Schema.DateTimeUtcFromMillis,
     completed: V2Schema.DateTimeUtcFromMillis.pipe(Schema.optional),

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -58,6 +58,7 @@ export type Event =
   | EventSessionNextShellEnded
   | EventSessionNextStepStarted
   | EventSessionNextStepEnded
+  | EventSessionNextStepFailed
   | EventSessionNextTextStarted
   | EventSessionNextTextDelta
   | EventSessionNextTextEnded
@@ -70,7 +71,7 @@ export type Event =
   | EventSessionNextToolCalled
   | EventSessionNextToolProgress
   | EventSessionNextToolSuccess
-  | EventSessionNextToolError
+  | EventSessionNextToolFailed
   | EventSessionNextRetried
   | EventSessionNextCompactionStarted
   | EventSessionNextCompactionDelta
@@ -823,6 +824,7 @@ export type GlobalEvent = {
     | EventSessionNextShellEnded
     | EventSessionNextStepStarted
     | EventSessionNextStepEnded
+    | EventSessionNextStepFailed
     | EventSessionNextTextStarted
     | EventSessionNextTextDelta
     | EventSessionNextTextEnded
@@ -835,7 +837,7 @@ export type GlobalEvent = {
     | EventSessionNextToolCalled
     | EventSessionNextToolProgress
     | EventSessionNextToolSuccess
-    | EventSessionNextToolError
+    | EventSessionNextToolFailed
     | EventSessionNextRetried
     | EventSessionNextCompactionStarted
     | EventSessionNextCompactionDelta
@@ -857,6 +859,7 @@ export type GlobalEvent = {
     | SyncEventSessionNextShellEnded
     | SyncEventSessionNextStepStarted
     | SyncEventSessionNextStepEnded
+    | SyncEventSessionNextStepFailed
     | SyncEventSessionNextTextStarted
     | SyncEventSessionNextTextDelta
     | SyncEventSessionNextTextEnded
@@ -869,7 +872,7 @@ export type GlobalEvent = {
     | SyncEventSessionNextToolCalled
     | SyncEventSessionNextToolProgress
     | SyncEventSessionNextToolSuccess
-    | SyncEventSessionNextToolError
+    | SyncEventSessionNextToolFailed
     | SyncEventSessionNextRetried
     | SyncEventSessionNextCompactionStarted
     | SyncEventSessionNextCompactionDelta
@@ -1973,6 +1976,22 @@ export type SyncEventSessionNextStepEnded = {
   }
 }
 
+export type SyncEventSessionNextStepFailed = {
+  type: "sync"
+  name: "session.next.step.failed.1"
+  id: string
+  seq: number
+  aggregateID: "sessionID"
+  data: {
+    timestamp: number
+    sessionID: string
+    error: {
+      type: string
+      message: string
+    }
+  }
+}
+
 export type SyncEventSessionNextTextStarted = {
   type: "sync"
   name: "session.next.text.started.1"
@@ -2157,9 +2176,9 @@ export type SyncEventSessionNextToolSuccess = {
   }
 }
 
-export type SyncEventSessionNextToolError = {
+export type SyncEventSessionNextToolFailed = {
   type: "sync"
-  name: "session.next.tool.error.1"
+  name: "session.next.tool.failed.1"
   id: string
   seq: number
   aggregateID: "sessionID"
@@ -2710,6 +2729,19 @@ export type EventSessionNextStepEnded = {
   }
 }
 
+export type EventSessionNextStepFailed = {
+  id: string
+  type: "session.next.step.failed"
+  properties: {
+    timestamp: number
+    sessionID: string
+    error: {
+      type: string
+      message: string
+    }
+  }
+}
+
 export type EventSessionNextTextStarted = {
   id: string
   type: "session.next.text.started"
@@ -2870,9 +2902,9 @@ export type EventSessionNextToolSuccess = {
   }
 }
 
-export type EventSessionNextToolError = {
+export type EventSessionNextToolFailed = {
   id: string
-  type: "session.next.tool.error"
+  type: "session.next.tool.failed"
   properties: {
     timestamp: number
     sessionID: string
@@ -3162,7 +3194,10 @@ export type SessionMessageAssistant = {
       write: number
     }
   }
-  error?: string
+  error?: {
+    type: string
+    message: string
+  }
 }
 
 export type SessionMessageCompaction = {