Resolve frontend warnings (vibe-kanban) (#1316)

* ## ✅ Batch 1 Complete

Successfully fixed all 6 warnings in batch 1 (message boundaries & streams):

### Changes made:

**[bridge.ts](file:///private/var/folders/m1/9q_ct1913z10v6wbnv54j25r0000gn/T/vibe-kanban/worktrees/19c9-resolve-frontend/frontend/src/vscode/bridge.ts)** - 5 fixes:
- Replaced `(window as any).InputEvent` checks with `typeof InputEvent === 'function'`
- Removed unnecessary type assertions on `dispatchEvent` calls
- More readable runtime guards using built-in DOM types

**[useJsonPatchWsStream.ts](file:///private/var/folders/m1/9q_ct1913z10v6wbnv54j25r0000gn/T/vibe-kanban/worktrees/19c9-resolve-frontend/frontend/src/hooks/useJsonPatchWsStream.ts)** - 1 fix:
- Added eslint suppression with explanation for `rfc6902` library requirement

**[frontend/package.json](file:///private/var/folders/m1/9q_ct1913z10v6wbnv54j25r0000gn/T/vibe-kanban/worktrees/19c9-resolve-frontend/frontend/package.json)**:
- Reduced `max-warnings` from 110 → 30 to lock in progress

### Results:
- **Before:** 32 warnings
- **After:** 26 warnings
- **Eliminated:** 6 warnings from batch 1
- **Remaining batches:** 2-6 (26 warnings)

* Perfect! ✅ The solution works without any `eslint-disable` comments.

## What we changed:

1. **Added type constraint**: `<T extends object>` - documents that JSON Patch only works on objects/arrays
2. **Used local variable narrowing**: `const current = dataRef.current` narrows `T | undefined` to `T`
3. **Removed the cast**: `applyPatch(next, filtered)` works directly since `applyPatch` already accepts `any`
4. **Cleaner code flow**: `const next = structuredClone(current)` then update refs

The code is now more readable, type-safe (within TypeScript's limits for this library), and passes both lint and typecheck with **no suppressions needed**.

frontend/package.json

@@ -8,7 +8,7 @@
     "build": "tsc && vite build",
     "check": "tsc --noEmit",
     "preview": "vite preview",
-    "lint": "eslint . --ext ts,tsx --report-unused-disable-directives --max-warnings 110",
+    "lint": "eslint . --ext ts,tsx --report-unused-disable-directives --max-warnings 30",
     "lint:fix": "eslint . --ext ts,tsx --fix",
     "lint:i18n": "LINT_I18N=true eslint . --ext ts,tsx --max-warnings 0",
     "format": "prettier --write \"src/**/*.{ts,tsx,js,jsx,json,css,md}\"",

frontend/src/hooks/useJsonPatchWsStream.ts

@@ -26,7 +26,7 @@ interface UseJsonPatchStreamResult<T> {
 /**
  * Generic hook for consuming WebSocket streams that send JSON messages with patches
  */
-export const useJsonPatchWsStream = <T>(
+export const useJsonPatchWsStream = <T extends object>(
   endpoint: string | undefined,
   enabled: boolean,
   initialData: () => T,
@@ -117,16 +117,17 @@ export const useJsonPatchWsStream = <T>(
               ? deduplicatePatches(patches)
               : patches;
 
-            if (!filtered.length || !dataRef.current) return;
+            const current = dataRef.current;
+            if (!filtered.length || !current) return;
 
             // Deep clone the current state before mutating it
-            dataRef.current = structuredClone(dataRef.current);
+            const next = structuredClone(current);
 
             // Apply patch (mutates the clone in place)
-            applyPatch(dataRef.current as any, filtered);
+            applyPatch(next, filtered);
 
-            // React re-render: dataRef.current is already a new object
-            setData(dataRef.current);
+            dataRef.current = next;
+            setData(next);
           }
 
           // Handle finished messages ({finished: true})

frontend/src/vscode/bridge.ts

@@ -152,15 +152,15 @@ function cutFromInput(el: HTMLInputElement | HTMLTextAreaElement) {
       el.value = before + after;
       el.setSelectionRange(start, start);
     }
-    const ie =
-      typeof (window as any).InputEvent !== 'undefined'
-        ? new (window as any).InputEvent('input', {
+    const ie: Event =
+      typeof InputEvent === 'function'
+        ? new InputEvent('input', {
             bubbles: true,
             composed: true,
             inputType: 'deleteByCut',
           })
         : new Event('input', { bubbles: true });
-    el.dispatchEvent(ie as Event);
+    el.dispatchEvent(ie);
     el.dispatchEvent(new Event('change', { bubbles: true }));
   }
 }
@@ -182,16 +182,16 @@ function pasteIntoInput(
     el.setSelectionRange(caret, caret);
   }
   el.focus();
-  const ie =
-    typeof (window as any).InputEvent !== 'undefined'
-      ? new (window as any).InputEvent('input', {
+  const ie: Event =
+    typeof InputEvent === 'function'
+      ? new InputEvent('input', {
           bubbles: true,
           composed: true,
           inputType: 'insertFromPaste',
           data: text,
         })
       : new Event('input', { bubbles: true });
-  el.dispatchEvent(ie as Event);
+  el.dispatchEvent(ie);
   el.dispatchEvent(new Event('change', { bubbles: true }));
 }
 
@@ -216,7 +216,7 @@ function insertTextAtCaretGeneric(text: string) {
   } else {
     try {
       document.execCommand('insertText', false, text);
-      (el as any).dispatchEvent?.(new Event('input', { bubbles: true }));
+      el.dispatchEvent(new Event('input', { bubbles: true }));
     } catch {
       (el as HTMLElement).innerText += text;
     }