fix(mothership): workspaceId is required end-to-end — no silent fallback path

Companion to the worker contract tightening. The requiredness propagates
up sim's own chain: the payload builder and the workflow branch carried
optional workspaceId that was never truly optional (the resolver's
'resolved' variant guarantees it; the workspace contract requires it) —
now typed as it always behaved. Regenerated protocol mirror.

Claude-Session: https://claude.ai/code/session_01CgaxNAaeD3taGdghbXn17w

Author: Sg312

apps/sim/lib/mothership/chat/payload.ts

@@ -420,7 +420,7 @@ export async function buildCopilotRequestPayload(
       : {}),
     messageId: userMessageId,
     ...(chatId ? { chatId } : {}),
-    ...(params.workspaceId ? { workspaceId: params.workspaceId } : {}),
+    workspaceId: params.workspaceId,
     ...(workflowId ? { workflowId } : {}),
     ...(allContexts.length > 0 ? { context: allContexts } : {}),
     ...(integrationTools.length > 0 ? { integrationTools } : {}),

apps/sim/lib/mothership/chat/post.ts

@@ -354,7 +354,9 @@ type UnifiedChatBranch =
       kind: 'workflow'
       workflowId: string
       workflowName?: string
-      workspaceId?: string
+      /** Always present: the resolver's 'resolved' variant guarantees it (the workflow's
+       * own workspace) — the wire contract requires it. */
+      workspaceId: string
       effectiveModel: string
       selectedModel: string
       mode: UnifiedChatRequest['mode']
@@ -376,7 +378,7 @@ type UnifiedChatBranch =
         effort?: 'low' | 'medium' | 'high' | 'xhigh' | 'max'
         workflowId: string
         workflowName?: string
-        workspaceId?: string
+        workspaceId: string
         mode: UnifiedChatRequest['mode']
         provider?: string
         commands?: string[]

apps/sim/lib/mothership/generated/protocol.ts

@@ -25,7 +25,10 @@ export interface ChatRequest {
   protocolVersion?: number | undefined;
   messageId?: string | undefined;
   chatId?: string | undefined;
-  workspaceId?: string | undefined;
+  /** Required: memories, analytics, and the chat row all key on it — sim always resolves
+   * it (workspace-scoped directly; workflow-scoped from the workflow). A missing value
+   * used to FABRICATE a random workspace identity per request. */
+  workspaceId: string;
   /** Workflow-scoped chats (the workflow-page copilot): the agent anchors to this workflow. */
   workflowId?: string | undefined;
   /** Connected-service operation schemas served by the integration gateway. */