diff --git a/src/components/ui/delegation-step.tsx b/src/components/ui/delegation-step.tsx
index 0c97535..b521e4c 100644
--- a/src/components/ui/delegation-step.tsx
+++ b/src/components/ui/delegation-step.tsx
@@ -212,7 +212,13 @@ export function DelegationStep({
           {delegationInfo?.isValid && (
             <div className="flex justify-end">
               <Button
-                onClick={clearDelegation}
+                onClick={async () => {
+                  const ok = await clearDelegation();
+                  if (ok) {
+                    // Refresh status so UI immediately reflects cleared state
+                    getDelegationStatus().then(setDelegationInfo).catch(console.error);
+                  }
+                }}
                 variant="outline"
                 size="sm"
                 className="text-red-400 border-red-400 hover:bg-red-400 hover:text-white"
diff --git a/src/contexts/AuthContext.tsx b/src/contexts/AuthContext.tsx
index cd531e9..c79d0b6 100644
--- a/src/contexts/AuthContext.tsx
+++ b/src/contexts/AuthContext.tsx
@@ -499,7 +499,8 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       const updatedUser = {
         ...currentUser,
         delegationExpiry: undefined,
-        browserPublicKey: undefined,
+        browserPubKey: undefined,
+        delegationSignature: undefined,
       };
       setCurrentUser(updatedUser);
       await saveUser(updatedUser);
diff --git a/src/hooks/actions/useAuthActions.ts b/src/hooks/actions/useAuthActions.ts
index c00eded..97e3dba 100644
--- a/src/hooks/actions/useAuthActions.ts
+++ b/src/hooks/actions/useAuthActions.ts
@@ -39,6 +39,7 @@ export function useAuthActions(): AuthActions {
     verifyOwnership,
     delegateKey: delegateKeyFromContext,
     getDelegationStatus,
+    clearDelegation: clearDelegationFromContext,
   } = useAuthContext();
   const { toast } = useToast();
 
@@ -255,13 +256,8 @@ export function useAuthActions(): AuthActions {
     }
 
     try {
-      // This would clear the delegation
-      // The actual implementation would use the DelegationManager
-
-      toast({
-        title: 'Delegation Cleared',
-        description: 'Your key delegation has been cleared.',
-      });
+      // Use the real clear implementation from AuthContext (includes toast)
+      await clearDelegationFromContext();
       return true;
     } catch (error) {
       console.error('Failed to clear delegation:', error);
@@ -272,7 +268,7 @@ export function useAuthActions(): AuthActions {
       });
       return false;
     }
-  }, [getDelegationStatus, toast]);
+  }, [getDelegationStatus, clearDelegationFromContext, toast]);
 
   // Renew delegation
   const renewDelegation = useCallback(
diff --git a/src/lib/database/LocalDatabase.ts b/src/lib/database/LocalDatabase.ts
index 3d4658e..237000c 100644
--- a/src/lib/database/LocalDatabase.ts
+++ b/src/lib/database/LocalDatabase.ts
@@ -77,12 +77,29 @@ export class LocalDatabase {
         signature?: unknown;
         browserPubKey?: unknown;
       };
-      console.warn('LocalDatabase: Rejecting invalid message', {
-        messageId: partialMsg?.id,
-        messageType: partialMsg?.type,
-        hasSignature: !!partialMsg?.signature,
-        hasBrowserPubKey: !!partialMsg?.browserPubKey,
-      });
+      // Get a detailed validation report for clearer diagnostics
+      try {
+        const report = await this.validator.getValidationReport(message);
+        console.warn('LocalDatabase: Rejecting invalid message', {
+          messageId: partialMsg?.id,
+          messageType: partialMsg?.type,
+          hasSignature: !!partialMsg?.signature,
+          hasBrowserPubKey: !!partialMsg?.browserPubKey,
+          hasValidSignature: report.hasValidSignature,
+          missingFields: report.missingFields,
+          invalidFields: report.invalidFields,
+          warnings: report.warnings,
+          errors: report.errors,
+        });
+      } catch (error) {
+        console.warn('LocalDatabase: Rejecting invalid message (no report)', {
+          messageId: partialMsg?.id,
+          messageType: partialMsg?.type,
+          hasSignature: !!partialMsg?.signature,
+          hasBrowserPubKey: !!partialMsg?.browserPubKey,
+          error: error instanceof Error ? error.message : String(error),
+        });
+      }
       return false;
     }
 
diff --git a/src/lib/delegation/crypto.ts b/src/lib/delegation/crypto.ts
index 7a4461e..d5daa15 100644
--- a/src/lib/delegation/crypto.ts
+++ b/src/lib/delegation/crypto.ts
@@ -25,8 +25,9 @@ export class DelegationCrypto {
     expiryTimestamp: number,
     nonce: string
   ): string {
-    const expiryDate = new Date(expiryTimestamp).toLocaleString();
-    return `I, ${walletAddress}, authorize browser key ${browserPublicKey} until ${expiryDate} (nonce: ${nonce})`;
+    const isoExpiry = new Date(expiryTimestamp).toISOString();
+    // Include both human-readable ISO and raw numeric timestamp for deterministic verification
+    return `I, ${walletAddress}, authorize browser key ${browserPublicKey} until ${isoExpiry} (ts:${expiryTimestamp}) (nonce: ${nonce})`;
   }
 
   /**
diff --git a/src/lib/delegation/index.ts b/src/lib/delegation/index.ts
index bb6d392..da36b11 100644
--- a/src/lib/delegation/index.ts
+++ b/src/lib/delegation/index.ts
@@ -159,6 +159,53 @@ export class DelegationManager {
     );
   }
 
+  /**
+   * Verify a signed message and return reasons when invalid
+   */
+  async verifyWithReason(
+    message: OpchanMessage
+  ): Promise<{ isValid: boolean; reasons: string[] }> {
+    const reasons: string[] = [];
+
+    // Check required fields
+    if (!message.signature) reasons.push('Missing message signature');
+    if (!message.browserPubKey) reasons.push('Missing browser public key');
+    if (!message.delegationProof) reasons.push('Missing delegation proof');
+    if (!message.author) reasons.push('Missing author address');
+    if (reasons.length > 0) return { isValid: false, reasons };
+
+    // Verify message signature
+    const signedContent = JSON.stringify({
+      ...message,
+      signature: undefined,
+      browserPubKey: undefined,
+      delegationProof: undefined,
+    });
+
+    const signatureOk = DelegationCrypto.verifyRaw(
+      signedContent,
+      message.signature,
+      message.browserPubKey
+    );
+    if (!signatureOk) {
+      reasons.push('Invalid message signature');
+      return { isValid: false, reasons };
+    }
+
+    // Verify delegation proof with details
+    const proofResult = await this.verifyProofWithReason(
+      message.delegationProof,
+      message.browserPubKey,
+      message.author
+    );
+    if (!proofResult.isValid) {
+      reasons.push(...proofResult.reasons);
+      return { isValid: false, reasons };
+    }
+
+    return { isValid: true, reasons: [] };
+  }
+
   /**
    * Get delegation status
    */
@@ -204,6 +251,9 @@ export class DelegationManager {
    */
   async clear(): Promise<void> {
     await DelegationStorage.clear();
+    // Invalidate in-memory cache immediately so UI reflects removal
+    this.cachedDelegation = null;
+    this.cachedAt = 0;
   }
 
   // ============================================================================
@@ -259,6 +309,53 @@ export class DelegationManager {
       proof.walletType
     );
   }
+
+  /**
+   * Verify delegation proof with detailed reasons
+   */
+  private async verifyProofWithReason(
+    proof: DelegationProof,
+    expectedBrowserKey: string,
+    expectedWalletAddress: string
+  ): Promise<{ isValid: boolean; reasons: string[] }> {
+    const reasons: string[] = [];
+
+    if (!proof?.walletAddress) reasons.push('Delegation missing wallet address');
+    if (!proof?.authMessage) reasons.push('Delegation missing auth message');
+    if (proof?.expiryTimestamp === undefined)
+      reasons.push('Delegation missing expiry timestamp');
+    if (reasons.length > 0) return { isValid: false, reasons };
+
+    if (proof.walletAddress !== expectedWalletAddress) {
+      reasons.push('Delegation wallet address does not match author');
+    }
+    if (Date.now() >= proof.expiryTimestamp) {
+      reasons.push('Delegation has expired');
+    }
+    if (
+      !proof.authMessage.includes(expectedWalletAddress) ||
+      !proof.authMessage.includes(expectedBrowserKey) ||
+      // Accept either raw numeric timestamp marker or ISO format containing the numeric timestamp marker we embed as ts:<num>
+      !(proof.authMessage.includes(`ts:${proof.expiryTimestamp}`) ||
+        proof.authMessage.includes(proof.expiryTimestamp.toString()))
+    ) {
+      reasons.push('Delegation auth message format mismatch');
+    }
+    if (reasons.length > 0) return { isValid: false, reasons };
+
+    const walletSigOk = await DelegationCrypto.verifyWalletSignature(
+      proof.authMessage,
+      proof.walletSignature,
+      proof.walletAddress,
+      proof.walletType
+    );
+
+    if (!walletSigOk) {
+      return { isValid: false, reasons: ['Invalid wallet signature for delegation'] };
+    }
+
+    return { isValid: true, reasons: [] };
+  }
 }
 
 // Export singleton instance
diff --git a/src/lib/utils/MessageValidator.ts b/src/lib/utils/MessageValidator.ts
index 8ec72fd..351ffa8 100644
--- a/src/lib/utils/MessageValidator.ts
+++ b/src/lib/utils/MessageValidator.ts
@@ -281,9 +281,22 @@ export class MessageValidator {
     errors: string[];
   }> {
     const structureReport = this.validateStructure(message);
-    const hasValidSignature = structureReport.isValid
-      ? await this.isValidMessage(message)
-      : false;
+    let hasValidSignature = false;
+    let signatureErrors: string[] = [];
+    if (structureReport.isValid) {
+      try {
+        const result = await this.getDelegationManager().verifyWithReason(
+          message as unknown as OpchanMessage
+        );
+        hasValidSignature = result.isValid;
+        signatureErrors = result.reasons;
+      } catch (err) {
+        hasValidSignature = false;
+        signatureErrors = [
+          err instanceof Error ? err.message : 'Unknown signature validation error',
+        ];
+      }
+    }
 
     return {
       ...structureReport,
@@ -291,6 +304,7 @@ export class MessageValidator {
       errors: [
         ...structureReport.missingFields,
         ...structureReport.invalidFields,
+        ...signatureErrors,
       ],
     };
   }