Fix handling of local-only slash commands (#432)

Instead of parsing <local-command-stdout> tags from the message stream,
intercept these commands early and forward
the clean result from the success handler directly to the client.
Applies to /context, /heapdump, and /extra-usage.

src/acp-agent.ts

@@ -227,6 +227,10 @@ function shouldHideClaudeAuth(): boolean {
 const IS_ROOT = (process.geteuid?.() ?? process.getuid?.()) === 0;
 const ALLOW_BYPASS = !IS_ROOT || !!process.env.IS_SANDBOX;
 
+// Slash commands that the SDK handles locally without replaying the user
+// message and without invoking the model.
+const LOCAL_ONLY_COMMANDS = new Set(["/context", "/heapdump", "/extra-usage"]);
+
 const PERMISSION_MODE_ALIASES: Record<string, PermissionMode> = {
   default: "default",
   acceptedits: "acceptEdits",
@@ -471,6 +475,16 @@ export class ClaudeAcpAgent implements Agent {
 
     let promptReplayed = false;
 
+    // These local-only commands return a result without replaying the user
+    // message. Mark promptReplayed=true so their result isn't consumed as a
+    // background task result.
+    const firstText = params.prompt[0]?.type === "text" ? params.prompt[0].text : "";
+    const isLocalOnlyCommand =
+      firstText.startsWith("/") && LOCAL_ONLY_COMMANDS.has(firstText.split(" ", 1)[0]);
+    if (isLocalOnlyCommand) {
+      promptReplayed = true;
+    }
+
     if (session.promptRunning) {
       session.input.push(userMessage);
       const order = session.nextPendingOrder++;
@@ -626,6 +640,20 @@ export class ClaudeAcpAgent implements Agent {
                 if (message.is_error) {
                   throw RequestError.internalError(undefined, message.result);
                 }
+                // For local-only commands (no model invocation), the result
+                // text is the command output — forward it to the client.
+                if (isLocalOnlyCommand) {
+                  for (const notification of toAcpNotifications(
+                    message.result,
+                    "assistant",
+                    params.sessionId,
+                    this.toolUseCache,
+                    this.client,
+                    this.logger,
+                  )) {
+                    await this.client.sessionUpdate(notification);
+                  }
+                }
                 return { stopReason: "end_turn", usage };
               }
               case "error_during_execution":
@@ -716,22 +744,6 @@ export class ClaudeAcpAgent implements Agent {
               typeof message.message.content === "string" &&
               message.message.content.includes("<local-command-stdout>")
             ) {
-              // Handle /context by sending its reply as regular agent message.
-              if (message.message.content.includes("Context Usage")) {
-                for (const notification of toAcpNotifications(
-                  message.message.content
-                    .replace("<local-command-stdout>", "")
-                    .replace("</local-command-stdout>", ""),
-                  "assistant",
-                  params.sessionId,
-                  this.toolUseCache,
-                  this.client,
-                  this.logger,
-                  { clientCapabilities: this.clientCapabilities },
-                )) {
-                  await this.client.sessionUpdate(notification);
-                }
-              }
               this.logger.log(message.message.content);
               break;
             }