Request Hold

Official Planned

Pause suspicious requests mid-flight for async verification, human approval, or extended analysis using Pingora's sleepable architecture.

Author: Sentinel Core Team License: Apache-2.0 Protocol: v0.1

Overview

Request Hold leverages Sentinel’s unique sleepable architecture (powered by Pingora) to pause requests mid-flight while performing extended verification. Unlike traditional proxies that must make instant decisions, Sentinel can hold a request for seconds or even minutes while waiting for async operations to complete.

This is a game-changer for security workflows that require:

  • Human approval for sensitive operations
  • Extended ML/AI analysis
  • External verification systems
  • Multi-factor authentication challenges

Why This Matters

Traditional proxies face a hard choice: block immediately or allow. There’s no middle ground. Request Hold introduces a third option: wait and verify.

Traditional Proxy:
    Request → Instant Decision (ms) → Block or Allow

Sentinel with Request Hold:
    Request → Initial Check → Hold (seconds/minutes) → Verify → Decide
                                      ↓
                             Async Verification
                             (Human / AI / External)

Planned Features

  • Sleepable Requests: Park requests without consuming threads (Pingora magic)
  • Human-in-the-Loop: Route high-risk requests to security team for approval
  • Challenge-Response: Present CAPTCHAs or MFA challenges inline
  • Webhook Verification: Call external systems and wait for approval
  • Timeout Policies: Configurable hold duration with fallback actions
  • Queue Management: Fair queuing to prevent resource exhaustion

Use Cases

  • High-Value Transactions: Hold large financial transfers for manual approval
  • Admin Actions: Require 2FA or team approval for destructive operations
  • Suspicious Logins: Challenge unusual login attempts with verification
  • Data Exports: Queue bulk data requests for compliance review
  • API Abuse: Slow down suspected scrapers without blocking legitimate users

How It Works

1. Request arrives at Sentinel
2. Request Hold agent flags it as "needs verification"
3. Sentinel parks the request (sleepable - no thread blocked)
4. Agent triggers async verification:
   - Webhook to approval system
   - Push notification to security team
   - CAPTCHA challenge to user
   - Extended AI analysis
5. Verification completes → Agent signals Sentinel
6. Sentinel resumes request → Forward or Block

Configuration (Preview)

agent "request-hold" {
    type "request_hold"
    transport "unix_socket" {
        path "/var/run/sentinel/request-hold.sock"
    }
    events ["request_headers" "request_body"]
    timeout-ms 300000  // 5 minute max hold
    failure-mode "closed"

    // Trigger conditions
    triggers {
        path-pattern "/api/admin/*"
        header "X-High-Risk" "true"
        risk-score-above 0.8
    }

    // Verification method
    verification "webhook" {
        url "https://approvals.internal/verify"
        timeout-secs 120
        include-request-context true
    }

    // Fallback if verification times out
    fallback "block" {
        status 403
        message "Request requires approval"
    }
}

Status

This agent is currently in the planning phase. This feature is uniquely enabled by Pingora’s async runtime. Follow the GitHub repository for updates.