Remove redundant assistant copy disabled state

- simplify assistant copy state to only track text and visibility
- stop passing always-false disabled props to the copy button
- update tests to match the narrower state shape

Author: shivamhwp

apps/web/src/components/chat/MessagesTimeline.logic.test.ts

@@ -158,7 +158,6 @@ describe("resolveAssistantMessageCopyState", () => {
         streaming: false,
       }),
     ).toEqual({
-      disabled: false,
       text: "Ship it",
       visible: true,
     });
@@ -172,7 +171,6 @@ describe("resolveAssistantMessageCopyState", () => {
         streaming: true,
       }),
     ).toEqual({
-      disabled: false,
       text: "Still streaming",
       visible: false,
     });
@@ -186,7 +184,6 @@ describe("resolveAssistantMessageCopyState", () => {
         streaming: false,
       }),
     ).toEqual({
-      disabled: false,
       text: null,
       visible: false,
     });
@@ -200,7 +197,6 @@ describe("resolveAssistantMessageCopyState", () => {
         streaming: false,
       }),
     ).toEqual({
-      disabled: false,
       text: "Interim thought",
       visible: false,
     });

apps/web/src/components/chat/MessagesTimeline.logic.ts

@@ -71,7 +71,6 @@ export function resolveAssistantMessageCopyState({
 }) {
   const hasText = text !== null && text.trim().length > 0;
   return {
-    disabled: false,
     text: hasText ? text : null,
     visible: showCopyButton && hasText && !streaming,
   };

apps/web/src/components/chat/MessagesTimeline.tsx

@@ -534,8 +534,6 @@ export const MessagesTimeline = memo(function MessagesTimeline({
                       <MessageCopyButton
                         text={assistantCopyState.text ?? ""}
                         title="Copy assistant response"
-                        disabled={assistantCopyState.disabled}
-                        disabledTitle="Copy available when response completes"
                         size="icon-xs"
                         variant="outline"
                         className="border-border/50 bg-background/35 text-muted-foreground/45 shadow-none hover:border-border/70 hover:bg-background/55 hover:text-muted-foreground/70"