diff --git a/packages/cli/tsconfig.json b/packages/cli/tsconfig.json
index 3d28e194..c78de016 100644
--- a/packages/cli/tsconfig.json
+++ b/packages/cli/tsconfig.json
@@ -23,6 +23,8 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
+    "noImplicitOverride": true,
+    "noFallthroughCasesInSwitch": true,
 
     // Interop and compatibility
     "skipLibCheck": true,
diff --git a/packages/core/src/events.ts b/packages/core/src/events.ts
index a6744cfa..1d9598c0 100644
--- a/packages/core/src/events.ts
+++ b/packages/core/src/events.ts
@@ -544,7 +544,7 @@ export class WebAgentEventEmitter extends EventEmitter {
   /**
    * Override emit to also trigger wildcard listeners
    */
-  emit(event: string | symbol, ...args: any[]): boolean {
+  override emit(event: string | symbol, ...args: any[]): boolean {
     const result = super.emit(event, ...args);
     // Also emit to wildcard listeners if this isn't already a wildcard event
     if (event !== "*") {
diff --git a/packages/core/src/loggers/filter.ts b/packages/core/src/loggers/filter.ts
index 01999d40..87714f1f 100644
--- a/packages/core/src/loggers/filter.ts
+++ b/packages/core/src/loggers/filter.ts
@@ -15,7 +15,7 @@ export abstract class LoggerFilter extends LoggerWrapper {
   private filteredEmitter: WebAgentEventEmitter | null = null;
   private handleEvent: ((eventType: string, data: any) => void) | null = null;
 
-  initialize(emitter: WebAgentEventEmitter): void {
+  override initialize(emitter: WebAgentEventEmitter): void {
     if (this.emitter) {
       this.dispose();
     }
@@ -36,7 +36,7 @@ export abstract class LoggerFilter extends LoggerWrapper {
     this.wrappedLogger.initialize(this.filteredEmitter);
   }
 
-  dispose(): void {
+  override dispose(): void {
     if (this.emitter && this.handleEvent) {
       this.emitter.off("*", this.handleEvent);
       this.wrappedLogger.dispose();
diff --git a/packages/core/src/loggers/metricsCollector.ts b/packages/core/src/loggers/metricsCollector.ts
index 61f95851..d5500967 100644
--- a/packages/core/src/loggers/metricsCollector.ts
+++ b/packages/core/src/loggers/metricsCollector.ts
@@ -21,7 +21,7 @@ export class MetricsCollector extends LoggerWrapper {
     super(wrappedLogger);
   }
 
-  initialize(emitter: WebAgentEventEmitter): void {
+  override initialize(emitter: WebAgentEventEmitter): void {
     this.stepCount = 0;
     this.aiGenerationCount = 0;
     this.aiGenerationErrorCount = 0;
@@ -39,7 +39,7 @@ export class MetricsCollector extends LoggerWrapper {
     super.initialize(emitter);
   }
 
-  dispose(): void {
+  override dispose(): void {
     if (this.emitter) {
       this.eventCounts.clear();
       this.emitter.off("*", this.handleEventCount);
diff --git a/packages/core/tsconfig.json b/packages/core/tsconfig.json
index 924efacc..99a85c0b 100644
--- a/packages/core/tsconfig.json
+++ b/packages/core/tsconfig.json
@@ -21,6 +21,8 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
+    "noImplicitOverride": true,
+    "noFallthroughCasesInSwitch": true,
 
     // Interop and compatibility
     "skipLibCheck": true,
diff --git a/packages/extension/tsconfig.json b/packages/extension/tsconfig.json
index 68387a59..04950e98 100644
--- a/packages/extension/tsconfig.json
+++ b/packages/extension/tsconfig.json
@@ -5,14 +5,11 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
-    // WXT 0.21's generated tsconfig enables these; opting out keeps the
-    // extension typecheck aligned with the rest of the monorepo (it also
-    // compiles pilo-core sources via the paths aliases below).
-    // Whether to adopt them monorepo-wide is tracked in
+    // noImplicitOverride and noFallthroughCasesInSwitch, which WXT 0.21's
+    // generated tsconfig also enables, are now on repo-wide. Only
+    // noUncheckedIndexedAccess remains opted out; see
     // https://github.com/mozilla/pilo/issues/688
     "noUncheckedIndexedAccess": false,
-    "noImplicitOverride": false,
-    "noFallthroughCasesInSwitch": false,
     "jsx": "react-jsx",
     "lib": ["ESNext", "DOM", "WebWorker"],
     "paths": {
diff --git a/packages/server/tsconfig.json b/packages/server/tsconfig.json
index 5cee4767..58ed8044 100644
--- a/packages/server/tsconfig.json
+++ b/packages/server/tsconfig.json
@@ -23,6 +23,8 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
+    "noImplicitOverride": true,
+    "noFallthroughCasesInSwitch": true,
 
     // Interop and compatibility
     "skipLibCheck": true,