refactor: fix and tighten mechanical lint rules

- no-useless-escape: drop needless backslashes in character classes and
  URL/path regexes (gh-cli, store, task, modelFilter, useFileMention,
  RoutineEditor, ScheduleForm).
- no-case-declarations: wrap case bodies in ProjectOverview and
  SettingsModal with block scopes.
- prefer-const: convert a never-reassigned slug binding in agent-import;
  annotate legitimate forward-declared let bindings in dashboard.ts that
  callbacks close over before assignment.
- no-fallthrough: add missing break after settings-subcommand error.
- no-empty-interface/no-empty-object-type: convert ProjectManifest from
  empty interface extension to a type alias.
- no-unused-expressions: replace `x && x.method()` short-circuits in
  TerminalModal with optional chaining.

Then ratchet these rules from warn → error so regressions are blocked.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/ProjectOverview.tsx

@@ -108,12 +108,13 @@ export function ProjectOverview({
         case "name":
           comparison = a.project.name.localeCompare(b.project.name);
           break;
-        case "activity":
+        case "activity": {
           const aTime = a.project.lastActivityAt || a.health?.lastActivityAt || a.project.updatedAt;
           const bTime = b.project.lastActivityAt || b.health?.lastActivityAt || b.project.updatedAt;
           comparison = new Date(bTime).getTime() - new Date(aTime).getTime();
           break;
-        case "status":
+        }
+        case "status": {
           const statusOrder: Record<ProjectStatus, number> = {
             errored: 0,
             initializing: 1,
@@ -122,6 +123,7 @@ export function ProjectOverview({
           };
           comparison = statusOrder[a.project.status] - statusOrder[b.project.status];
           break;
+        }
       }
 
       return sortDirection === "asc" ? comparison : -comparison;

packages/dashboard/app/components/RoutineEditor.tsx

@@ -52,7 +52,7 @@ function isLikelyCron(expr: string): boolean {
   const parts = expr.trim().split(/\s+/);
   if (parts.length !== 5) return false;
   // Each field should contain digits, *, /, -, or ,
-  return parts.every((p) => /^[\d*,/\-]+$/.test(p));
+  return parts.every((p) => /^[\d*,/-]+$/.test(p));
 }
 
 /**

packages/dashboard/app/components/ScheduleForm.tsx

@@ -43,7 +43,7 @@ function isLikelyCron(expr: string): boolean {
   const parts = expr.trim().split(/\s+/);
   if (parts.length !== 5) return false;
   // Each field should contain digits, *, /, -, or ,
-  return parts.every((p) => /^[\d*,/\-]+$/.test(p));
+  return parts.every((p) => /^[\d*,/-]+$/.test(p));
 }
 
 /**

packages/dashboard/app/components/SettingsModal.tsx

@@ -3024,7 +3024,7 @@ export function SettingsModal({
         );
       case "pi-extensions":
         return <PiExtensionsManager addToast={addToast} projectId={projectId} />;
-      case "authentication":
+      case "authentication": {
         // CLI-backed providers (currently just claude-cli) render their own
         // compact card with Enable/Disable + Test actions — bypassing the
         // OAuth/API-key rendering below. Filter them out of the standard
@@ -3231,6 +3231,7 @@ export function SettingsModal({
             )}
           </>
         );
+      }
     }
   };
 

packages/dashboard/app/components/TerminalModal.tsx

@@ -610,7 +610,7 @@ export function TerminalModal({ isOpen, onClose, initialCommand, projectId }: Te
         if (xtermRef.current) {
           const currentSize = xtermRef.current.options.fontSize || 14;
           xtermRef.current.options.fontSize = Math.min(currentSize + 1, 32);
-          fitAddonRef.current && (fitAddonRef.current as InstanceType<typeof FitAddon>).fit();
+          (fitAddonRef.current as InstanceType<typeof FitAddon> | null)?.fit();
         }
         return;
       }
@@ -621,7 +621,7 @@ export function TerminalModal({ isOpen, onClose, initialCommand, projectId }: Te
         if (xtermRef.current) {
           const currentSize = xtermRef.current.options.fontSize || 14;
           xtermRef.current.options.fontSize = Math.max(currentSize - 1, 8);
-          fitAddonRef.current && (fitAddonRef.current as InstanceType<typeof FitAddon>).fit();
+          (fitAddonRef.current as InstanceType<typeof FitAddon> | null)?.fit();
         }
         return;
       }
@@ -631,7 +631,7 @@ export function TerminalModal({ isOpen, onClose, initialCommand, projectId }: Te
         e.preventDefault();
         if (xtermRef.current) {
           xtermRef.current.options.fontSize = 14;
-          fitAddonRef.current && (fitAddonRef.current as InstanceType<typeof FitAddon>).fit();
+          (fitAddonRef.current as InstanceType<typeof FitAddon> | null)?.fit();
         }
         return;
       }

packages/dashboard/app/hooks/useFileMention.ts

@@ -71,7 +71,7 @@ export function useFileMention(options: UseFileMentionOptions = {}): UseFileMent
     }
 
     // Path characters: alphanumeric, /, _, -, .
-    const isPathChar = (char: string): boolean => /[a-zA-Z0-9/_.\-]/.test(char);
+    const isPathChar = (char: string): boolean => /[a-zA-Z0-9/_.-]/.test(char);
 
     // Find # by scanning backwards from cursor
     // Skip over path chars (they're part of the mention text)

packages/dashboard/app/utils/modelFilter.ts

@@ -8,7 +8,7 @@ import type { ModelInfo } from "../api";
  * Preserves spaces (which serve as field/word boundaries) and alphanumeric chars.
  */
 function normalize(s: string): string {
-  return s.toLowerCase().replace(/[-_.\/]/g, "");
+  return s.toLowerCase().replace(/[-_./]/g, "");
 }
 
 /**