diff --git a/lib/constructs/bedrock-agent.ts b/lib/constructs/bedrock-agent.ts
index c19c7e5..c23efa2 100644
--- a/lib/constructs/bedrock-agent.ts
+++ b/lib/constructs/bedrock-agent.ts
@@ -205,12 +205,65 @@ Use the knowledge base for policy, SOP, SA8000 compliance, and handbook question
 
 Keep responses concise, professional, and actionable.`;
 
+    // ── Guardrail (audit M-19) ────────────────────────────────────────────────
+    // Scope: prompt-attack + content filters + masking of credential/financial
+    // identifiers. Names, emails, and phone numbers are deliberately NOT masked —
+    // returning vendor contacts and payment/WO/PO details is Alex's core job.
+    const guardrail = new bedrock.CfnGuardrail(this, 'Guardrail', {
+      name: 'seahaven-alex-guardrail',
+      description: 'Prompt-attack, content, and sensitive-identifier guardrail for Alex',
+      blockedInputMessaging:
+        "Sorry, I can't help with that request. If you think this was blocked in error, contact IT.",
+      blockedOutputsMessaging:
+        'Part of that response was withheld by policy. If you need this information, contact IT.',
+      contentPolicyConfig: {
+        filtersConfig: [
+          // outputStrength must be NONE for PROMPT_ATTACK per the Guardrails API
+          { type: 'PROMPT_ATTACK', inputStrength: 'HIGH', outputStrength: 'NONE' },
+          { type: 'HATE', inputStrength: 'HIGH', outputStrength: 'HIGH' },
+          { type: 'INSULTS', inputStrength: 'HIGH', outputStrength: 'HIGH' },
+          { type: 'SEXUAL', inputStrength: 'HIGH', outputStrength: 'HIGH' },
+          { type: 'VIOLENCE', inputStrength: 'HIGH', outputStrength: 'HIGH' },
+          // Output at MEDIUM: Alex legitimately answers SA8000/HR questions about
+          // handling misconduct reports; HIGH output filtering suppresses those.
+          { type: 'MISCONDUCT', inputStrength: 'HIGH', outputStrength: 'MEDIUM' },
+        ],
+      },
+      sensitiveInformationPolicyConfig: {
+        piiEntitiesConfig: [
+          { type: 'US_SOCIAL_SECURITY_NUMBER', action: 'ANONYMIZE' },
+          { type: 'CREDIT_DEBIT_CARD_NUMBER', action: 'ANONYMIZE' },
+          { type: 'US_BANK_ACCOUNT_NUMBER', action: 'ANONYMIZE' },
+          { type: 'US_BANK_ROUTING_NUMBER', action: 'ANONYMIZE' },
+          { type: 'PASSWORD', action: 'ANONYMIZE' },
+          { type: 'AWS_ACCESS_KEY', action: 'ANONYMIZE' },
+          { type: 'AWS_SECRET_KEY', action: 'ANONYMIZE' },
+        ],
+      },
+    });
+
+    const guardrailVersion = new bedrock.CfnGuardrailVersion(this, 'GuardrailVersion', {
+      guardrailIdentifier: guardrail.attrGuardrailId,
+      description: 'Initial version — prompt-attack + content + credential/financial masking',
+    });
+    guardrailVersion.addDependency(guardrail);
+
+    agentRole.addToPolicy(new iam.PolicyStatement({
+      actions: ['bedrock:ApplyGuardrail'],
+      // Base ARN plus version-suffixed children — runtime applies the versioned guardrail
+      resources: [guardrail.attrGuardrailArn, `${guardrail.attrGuardrailArn}/*`],
+    }));
+
     // ── CfnAgent ──────────────────────────────────────────────────────────────
     this.agent = new bedrock.CfnAgent(this, 'Agent', {
       agentName: 'seahaven-alex',
       description: 'Alex — Sea Haven Industries internal Slack assistant',
       agentResourceRoleArn: agentRole.roleArn,
       foundationModel: BedrockAgentConstruct.MODEL_ID,
+      guardrailConfiguration: {
+        guardrailIdentifier: guardrail.attrGuardrailId,
+        guardrailVersion: guardrailVersion.attrVersion,
+      },
       instruction,
       idleSessionTtlInSeconds: 1800, // 30 min — matches the processor's session window
       knowledgeBases: [
@@ -357,12 +410,17 @@ Keep responses concise, professional, and actionable.`;
       ],
     });
 
+    // Guardrail version must exist before the agent references it (review FIX)
+    this.agent.addDependency(guardrailVersion);
+
     // ── Agent alias (stable ARN for invocations) ──────────────────────────────
     // Creating the alias also triggers agent preparation in CloudFormation.
     this.agentAlias = new bedrock.CfnAgentAlias(this, 'AgentAlias', {
       agentId: this.agent.attrAgentId,
       agentAliasName: 'live',
-      description: 'Production alias — Alex v1',
+      // Description bump forces an alias update so a new agent version snapshots
+      // the guardrail config — CfnAgentAlias does not pick up agent changes otherwise.
+      description: 'Production alias — Alex v2 (guardrail)',
     });
   }
 }