✨ feat(workspace): accept workspaceRoot as explicit request body field

Add workspaceRoot as an optional field in ChatCompletionRequest so
clients can explicitly pass the workspace directory. Resolution order:
1. body.workspaceRoot (explicit from client)
2. extractWorkspaceFromMessages() (parsed from system message)
3. process.cwd() (server working directory fallback)

Author: hletrd

plugin/src/server.ts

@@ -29,6 +29,7 @@ interface ChatCompletionRequest {
   model?: string;
   messages?: ChatMessage[];
   stream?: boolean;
+  workspaceRoot?: string;
 }
 
 // ACP Protocol Types
@@ -751,7 +752,7 @@ async function handleChatCompletions(
     const messages = body.messages;
     const stream = body.stream ?? false;
     const model = body.model ?? DEFAULT_MODEL;
-    const workspaceRoot = extractWorkspaceFromMessages(messages) ?? undefined;
+    const workspaceRoot = body.workspaceRoot ?? extractWorkspaceFromMessages(messages) ?? undefined;
     const prompt = formatMessages(messages);
 
     if (stream) {

src/server.ts

@@ -31,6 +31,7 @@ interface ChatCompletionRequest {
   model?: string;
   messages?: ChatMessage[];
   stream?: boolean;
+  workspaceRoot?: string;
 }
 
 // ACP Protocol Types - Session Update Types
@@ -1543,8 +1544,8 @@ async function handleChatCompletions(req: IncomingMessage, res: ServerResponse):
     const stream = body.stream ?? false;
     const model = body.model ?? DEFAULT_MODEL;
 
-    // Extract workspace root from messages (OpenCode sends this in system message)
-    const workspaceRoot = extractWorkspaceFromMessages(messages);
+    // Extract workspace root: prefer explicit field, then parse from messages
+    const workspaceRoot = body.workspaceRoot ?? extractWorkspaceFromMessages(messages);
     if (workspaceRoot) {
       structuredLog('info', 'Request', `Extracted workspace: ${workspaceRoot}`, { requestId });
     }