Glossary
Reliability and AI-safety terms, explained with real incidents
Plain-language definitions of the ideas that keep software from failing the same way twice. Each one comes with an incident where it mattered, and what to do about it.
20 terms
- Audit trailAlso: Audit logA tamper-resistant record of who did what, to which object, when and why, used to investigate incidents and prove compliance.Example: Okta
- Blast radiusHow much breaks when one thing goes wrong. Good design keeps it small, so a single failure affects one region, customer or feature rather than everything.Example: Google Cloud
- Canary releaseAlso: Staged rollout, Progressive deliveryRolling a change out to a small slice of servers or users first, watching for problems, and only then expanding it.Example: CrowdStrike
- Circuit breakerA guard around calls to a dependency that stops sending requests when the dependency is failing, then tries again carefully once it recovers.Example: Slack
- Exponential backoff with jitterAlso: Retry backoff, JitterA retry strategy where each attempt waits longer than the last, plus a random amount, so failing clients don’t all retry at the same moment.Example: Amazon Web Services
- Human-in-the-loop approvalAlso: Approval gate, Four-eyes principleRequiring a person to approve high-impact actions before automation carries them out, enforced in code the automation can’t bypass.Example: Citibank
- Idempotency keyA unique value sent with a request so the server can recognize a retry and return the original result instead of doing the work twice.Example: Stripe
- Insecure direct object reference (IDOR)Also: Broken object-level authorization, BOLAA flaw where an application uses an ID from the request to fetch data without checking that the caller is allowed to see it.Example: First American Financial
- Kill switchAlso: Feature flagA control that lets you stop an automated system or a feature immediately, without waiting for a deploy.Example: Knight Capital
- Known Exploited Vulnerabilities (KEV)Also: CISA KEV catalogCISA’s catalog of vulnerabilities that attackers are actively exploiting, used to decide what to patch first.Example: MOVEit Transfer customers
- Least privilegeGiving every person, service and AI agent only the access its task requires, and nothing more.Example: Replit
- Model Context Protocol (MCP)Also: MCP serverAn open protocol that connects AI assistants to tools and data sources, such as databases, code hosts and APIs, through a standard interface.Example: Supabase MCP users
- Network segmentationAlso: Microsegmentation, Zero trustDividing a network into separate zones so a compromise in one place can’t freely reach everything else.Example: Target
- Optimistic concurrency controlAlso: Compare-and-set, Version checkUpdating a record only if it hasn’t changed since you read it, usually by checking a version number, so stale decisions aren’t applied.Example: Amazon Web Services
- Phishing-resistant MFAAlso: Passkeys, FIDO2, Security keysMulti-factor authentication that can’t be phished or relayed, such as passkeys and hardware security keys tied to the real website.Example: Uber
- PostmortemAlso: Incident report, Blameless postmortem, Root cause analysisA written account of an incident, covering what happened, why, what it affected and what will change, written to learn from it rather than to assign blame.Example: Cloudflare
- Prompt injectionAlso: Indirect prompt injectionAn attack where text an AI model reads, such as an email, web page or document, contains instructions that the model then follows.Example: GitHub MCP users
- ReconciliationRegularly comparing two systems that should agree, such as your orders and your payment provider, and flagging or fixing any difference.Example: GitHub
- Restore testingAlso: Backup verificationRegularly restoring backups to prove they work, rather than trusting that backup jobs report success.Example: GitLab
- Software bill of materials (SBOM)An inventory of every component and dependency in a piece of software, so you can find out quickly where a vulnerable one is running.Example: Apache Log4j users