Refactor agent loop (#4412)

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

@@ -142,6 +142,21 @@ export namespace MessageV2 {
   })
   export type AgentPart = z.infer<typeof AgentPart>
 
+  export const CompactionPart = PartBase.extend({
+    type: z.literal("compaction"),
+  }).meta({
+    ref: "CompactionPart",
+  })
+  export type CompactionPart = z.infer<typeof CompactionPart>
+
+  export const SubtaskPart = PartBase.extend({
+    type: z.literal("subtask"),
+    prompt: z.string(),
+    description: z.string(),
+    agent: z.string(),
+  })
+  export type SubtaskPart = z.infer<typeof SubtaskPart>
+
   export const RetryPart = PartBase.extend({
     type: z.literal("retry"),
     attempt: z.number(),
@@ -277,6 +292,13 @@ export namespace MessageV2 {
         diffs: Snapshot.FileDiff.array(),
       })
       .optional(),
+    agent: z.string(),
+    model: z.object({
+      providerID: z.string(),
+      modelID: z.string(),
+    }),
+    system: z.string().optional(),
+    tools: z.record(z.string(), z.boolean()).optional(),
   }).meta({
     ref: "UserMessage",
   })
@@ -285,6 +307,7 @@ export namespace MessageV2 {
   export const Part = z
     .discriminatedUnion("type", [
       TextPart,
+      SubtaskPart,
       ReasoningPart,
       FilePart,
       ToolPart,
@@ -294,6 +317,7 @@ export namespace MessageV2 {
       PatchPart,
       AgentPart,
       RetryPart,
+      CompactionPart,
     ])
     .meta({
       ref: "Part",
@@ -334,6 +358,7 @@ export namespace MessageV2 {
         write: z.number(),
       }),
     }),
+    finish: z.string().optional(),
   }).meta({
     ref: "AssistantMessage",
   })
@@ -482,6 +507,11 @@ export namespace MessageV2 {
         time: {
           created: v1.metadata.time.created,
         },
+        agent: "build",
+        model: {
+          providerID: "opencode",
+          modelID: "opencode",
+        },
       }
       const parts = v1.parts.flatMap((part): Part[] => {
         const base = {
@@ -529,107 +559,107 @@ export namespace MessageV2 {
       if (msg.parts.length === 0) continue
 
       if (msg.info.role === "user") {
-        result.push({
+        const userMessage: UIMessage = {
           id: msg.info.id,
           role: "user",
-          parts: msg.parts.flatMap((part): UIMessage["parts"] => {
-            if (part.type === "text")
-              return [
-                {
-                  type: "text",
-                  text: part.text,
-                },
-              ]
-            // text/plain and directory files are converted into text parts, ignore them
-            if (part.type === "file" && part.mime !== "text/plain" && part.mime !== "application/x-directory")
-              return [
-                {
-                  type: "file",
-                  url: part.url,
-                  mediaType: part.mime,
-                  filename: part.filename,
-                },
-              ]
-            return []
-          }),
-        })
+          parts: [],
+        }
+        result.push(userMessage)
+        for (const part of msg.parts) {
+          if (part.type === "text")
+            userMessage.parts.push({
+              type: "text",
+              text: part.text,
+            })
+          // text/plain and directory files are converted into text parts, ignore them
+          if (part.type === "file" && part.mime !== "text/plain" && part.mime !== "application/x-directory")
+            userMessage.parts.push({
+              type: "file",
+              url: part.url,
+              mediaType: part.mime,
+              filename: part.filename,
+            })
+
+          if (part.type === "compaction") {
+            userMessage.parts.push({
+              type: "text",
+              text: "What did we do so far?",
+            })
+          }
+          if (part.type === "subtask") {
+            userMessage.parts.push({
+              type: "text",
+              text: "The following tool was executed by the user",
+            })
+          }
+        }
       }
 
       if (msg.info.role === "assistant") {
-        result.push({
+        const assistantMessage: UIMessage = {
           id: msg.info.id,
           role: "assistant",
-          parts: msg.parts.flatMap((part): UIMessage["parts"] => {
-            if (part.type === "text")
-              return [
-                {
-                  type: "text",
-                  text: part.text,
-                  providerMetadata: part.metadata,
-                },
-              ]
-            if (part.type === "step-start")
-              return [
-                {
-                  type: "step-start",
-                },
-              ]
-            if (part.type === "tool") {
-              if (part.state.status === "completed") {
-                if (part.state.attachments?.length) {
-                  result.push({
-                    id: Identifier.ascending("message"),
-                    role: "user",
-                    parts: [
-                      {
-                        type: "text",
-                        text: `Tool ${part.tool} returned an attachment:`,
-                      },
-                      ...part.state.attachments.map((attachment) => ({
-                        type: "file" as const,
-                        url: attachment.url,
-                        mediaType: attachment.mime,
-                        filename: attachment.filename,
-                      })),
-                    ],
-                  })
-                }
-                return [
-                  {
-                    type: ("tool-" + part.tool) as `tool-${string}`,
-                    state: "output-available",
-                    toolCallId: part.callID,
-                    input: part.state.input,
-                    output: part.state.time.compacted ? "[Old tool result content cleared]" : part.state.output,
-                    callProviderMetadata: part.metadata,
-                  },
-                ]
+          parts: [],
+        }
+        result.push(assistantMessage)
+        for (const part of msg.parts) {
+          if (part.type === "text")
+            assistantMessage.parts.push({
+              type: "text",
+              text: part.text,
+              providerMetadata: part.metadata,
+            })
+          if (part.type === "step-start")
+            assistantMessage.parts.push({
+              type: "step-start",
+            })
+          if (part.type === "tool") {
+            if (part.state.status === "completed") {
+              if (part.state.attachments?.length) {
+                result.push({
+                  id: Identifier.ascending("message"),
+                  role: "user",
+                  parts: [
+                    {
+                      type: "text",
+                      text: `Tool ${part.tool} returned an attachment:`,
+                    },
+                    ...part.state.attachments.map((attachment) => ({
+                      type: "file" as const,
+                      url: attachment.url,
+                      mediaType: attachment.mime,
+                      filename: attachment.filename,
+                    })),
+                  ],
+                })
               }
-              if (part.state.status === "error")
-                return [
-                  {
-                    type: ("tool-" + part.tool) as `tool-${string}`,
-                    state: "output-error",
-                    toolCallId: part.callID,
-                    input: part.state.input,
-                    errorText: part.state.error,
-                    callProviderMetadata: part.metadata,
-                  },
-                ]
+              assistantMessage.parts.push({
+                type: ("tool-" + part.tool) as `tool-${string}`,
+                state: "output-available",
+                toolCallId: part.callID,
+                input: part.state.input,
+                output: part.state.time.compacted ? "[Old tool result content cleared]" : part.state.output,
+                callProviderMetadata: part.metadata,
+              })
             }
-            if (part.type === "reasoning") {
-              return [
-                {
-                  type: "reasoning",
-                  text: part.text,
-                  providerMetadata: part.metadata,
-                },
-              ]
-            }
-
-            return []
-          }),
-        })
+            if (part.state.status === "error")
+              assistantMessage.parts.push({
+                type: ("tool-" + part.tool) as `tool-${string}`,
+                state: "output-error",
+                toolCallId: part.callID,
+                input: part.state.input,
+                errorText: part.state.error,
+                callProviderMetadata: part.metadata,
+              })
+          }
+          if (part.type === "reasoning") {
+            assistantMessage.parts.push({
+              type: "reasoning",
+              text: part.text,
+              providerMetadata: part.metadata,
+            })
+          }
+        }
       }
     }
 
@@ -671,9 +701,16 @@ export namespace MessageV2 {
 
   export async function filterCompacted(stream: AsyncIterable<MessageV2.WithParts>) {
     const result = [] as MessageV2.WithParts[]
+    const completed = new Set<string>()
     for await (const msg of stream) {
       result.push(msg)
-      if (msg.info.role === "assistant" && msg.info.summary === true) break
+      if (
+        msg.info.role === "user" &&
+        completed.has(msg.info.id) &&
+        msg.parts.some((part) => part.type === "compaction")
+      )
+        break
+      if (msg.info.role === "assistant" && msg.info.summary && msg.info.finish) completed.add(msg.info.parentID)
     }
     result.reverse()
     return result