feat(acp): Add messageID and emit user_message_chunk on prompt/command (#18625)

Co-authored-by: Aiden Cline <[email protected]>

bun.lock

@@ -306,7 +306,7 @@
       "dependencies": {
         "@actions/core": "1.11.1",
         "@actions/github": "6.0.1",
-        "@agentclientprotocol/sdk": "0.14.1",
+        "@agentclientprotocol/sdk": "0.16.1",
         "@ai-sdk/amazon-bedrock": "4.0.83",
         "@ai-sdk/anthropic": "3.0.64",
         "@ai-sdk/azure": "3.0.49",
@@ -680,7 +680,7 @@
 
     "@adobe/css-tools": ["@adobe/[email protected]", "", {}, "sha512-Elp+iwUx5rN5+Y8xLt5/GRoG20WGoDCQ/1Fb+1LiGtvwbDavuSk0jhD/eZdckHAuzcDzccnkv+rEjyWfRx18gg=="],
 
-    "@agentclientprotocol/sdk": ["@agentclientprotocol/[email protected]4.1", "", { "peerDependencies": { "zod": "^3.25.0 || ^4.0.0" } }, "sha512-b6r3PS3Nly+Wyw9U+0nOr47bV8tfS476EgyEMhoKvJCZLbgqoDFN7DJwkxL88RR0aiOqOYV1ZnESHqb+RmdH8w=="],
+    "@agentclientprotocol/sdk": ["@agentclientprotocol/[email protected]6.1", "", { "peerDependencies": { "zod": "^3.25.0 || ^4.0.0" } }, "sha512-1ad+Sc/0sCtZGHthxxvgEUo5Wsbw16I+aF+YwdiLnPwkZG8KAGUEAPK6LM6Pf69lCyJPt1Aomk1d+8oE3C4ZEw=="],
 
     "@ai-sdk/amazon-bedrock": ["@ai-sdk/[email protected]", "", { "dependencies": { "@ai-sdk/anthropic": "3.0.64", "@ai-sdk/provider": "3.0.8", "@ai-sdk/provider-utils": "4.0.21", "@smithy/eventstream-codec": "^4.0.1", "@smithy/util-utf8": "^4.0.0", "aws4fetch": "^1.0.20" }, "peerDependencies": { "zod": "^3.25.76 || ^4.1.8" } }, "sha512-DoRpvIWGU/r83UeJAM9L93Lca8Kf/yP5fIhfEOltMPGP/PXrGe0BZaz0maLSRn8djJ6+HzWIsgu5ZI6bZqXEXg=="],
 

packages/opencode/package.json

@@ -69,7 +69,7 @@
   "dependencies": {
     "@actions/core": "1.11.1",
     "@actions/github": "6.0.1",
-    "@agentclientprotocol/sdk": "0.14.1",
+    "@agentclientprotocol/sdk": "0.16.1",
     "@ai-sdk/amazon-bedrock": "4.0.83",
     "@ai-sdk/anthropic": "3.0.64",
     "@ai-sdk/azure": "3.0.49",

packages/opencode/src/acp/agent.ts

@@ -449,6 +449,19 @@ export namespace ACP {
                 return
             }
           }
+          if (part.type !== "text" && part.type !== "file") return
+          const msg = await this.sdk.session
+            .message(
+              { sessionID: part.sessionID, messageID: part.messageID, directory: session.cwd },
+              { throwOnError: true },
+            )
+            .then((x) => x.data)
+            .catch((err) => {
+              log.error("failed to fetch message for user chunk", { error: err })
+              return undefined
+            })
+          if (!msg || msg.info.role !== "user") return
+          await this.processMessage({ info: msg.info, parts: [part] })
           return
         }
 
@@ -484,6 +497,7 @@ export namespace ACP {
                 sessionId,
                 update: {
                   sessionUpdate: "agent_message_chunk",
+                  messageId: props.messageID,
                   content: {
                     type: "text",
                     text: props.delta,
@@ -502,6 +516,7 @@ export namespace ACP {
                 sessionId,
                 update: {
                   sessionUpdate: "agent_thought_chunk",
+                  messageId: props.messageID,
                   content: {
                     type: "text",
                     text: props.delta,
@@ -666,7 +681,7 @@ export namespace ACP {
       }
     }
 
-    async unstable_listSessions(params: ListSessionsRequest): Promise<ListSessionsResponse> {
+    async listSessions(params: ListSessionsRequest): Promise<ListSessionsResponse> {
       try {
         const cursor = params.cursor ? Number(params.cursor) : undefined
         const limit = 100
@@ -970,6 +985,7 @@ export namespace ACP {
                 sessionId,
                 update: {
                   sessionUpdate: message.info.role === "user" ? "user_message_chunk" : "agent_message_chunk",
+                  messageId: message.info.id,
                   content: {
                     type: "text",
                     text: part.text,
@@ -1001,6 +1017,7 @@ export namespace ACP {
                 sessionId,
                 update: {
                   sessionUpdate: messageChunk,
+                  messageId: message.info.id,
                   content: { type: "resource_link", uri: url, name: filename, mimeType: mime },
                 },
               })
@@ -1022,6 +1039,7 @@ export namespace ACP {
                   sessionId,
                   update: {
                     sessionUpdate: messageChunk,
+                    messageId: message.info.id,
                     content: {
                       type: "image",
                       mimeType: effectiveMime,
@@ -1050,6 +1068,7 @@ export namespace ACP {
                   sessionId,
                   update: {
                     sessionUpdate: messageChunk,
+                    messageId: message.info.id,
                     content: { type: "resource", resource },
                   },
                 })
@@ -1066,6 +1085,7 @@ export namespace ACP {
                 sessionId,
                 update: {
                   sessionUpdate: "agent_thought_chunk",
+                  messageId: message.info.id,
                   content: {
                     type: "text",
                     text: part.text,

packages/opencode/test/acp/agent-interface.test.ts

@@ -35,7 +35,7 @@ describe("acp.agent interface compliance", () => {
     "setSessionMode",
     "authenticate",
     // Unstable - SDK checks these with unstable_ prefix
-    "unstable_listSessions",
+    "listSessions",
     "unstable_forkSession",
     "unstable_resumeSession",
     "unstable_setSessionModel",