LLM Guardrails Pipeline

Design a guardrails pipeline that wraps an LLM application with layered input and output safety.

00

Practice checkpoints

The requirements are open as a taste. From the numbers onward, the full guide opens in the app.

  1. 01
    Clarify scope
  2. 02
    Requirements + scale
  3. 03
    API + data modelUnlocks in the app
  4. 04
    Draw architectureUnlocks in the app
  5. 05
    Deep diveUnlocks in the app
  6. 06
    Trade-off decisionUnlocks in the app
01

Requirements that shape the design

Do not only state requirements. Ask for them. Each card pairs the design constraint with a clarification question you can say out loud before drawing the architecture.

Functional requirements

01What exactly does this wrap — one chatbot, or every LLM call in the company?

One shared pipeline wraps every prompt and every response: applications declare a policy, and the same rails run for chat, RAG (answers grounded in retrieved documents), and agents — safety logic exists once, not re-invented per team — and the rails include topical bounds (keeping the conversation inside declared subject areas), not only harm screening.

02What happens to a prompt before the model ever sees it?

Input rails classify the prompt for injection and jailbreak attempts and detect PII, masking it before the prompt ever leaves our boundary for a model provider.

03The user pastes a document — is that treated like their own words?

No: pasted and retrieved content is data, never instructions — a retrieval rail scans it for embedded commands, because indirect injection rides in on documents, not on what the user typed.

04What happens to the model’s answer before the user sees it?

Output rails redact PII, classify the text against policy, and check grounding against the sources — an answer that leaks a phone number or invents a claim is caught before display, not after.

05The model wants to call a tool — does it just run?

Never directly: every tool call passes a gate — allowlist, schema-validated arguments, and a risk tier where destructive actions require explicit confirmation or a human.

06What does a blocked user actually see?

A safe, specific message with a retry or appeal path — and the decision is logged with detector scores and the policy version that made it, so a wrong block can be explained and fixed.

Out of scopePlatform-scale UGC moderation (the Moderation Service question — user posts, not LLM I/O) · Alignment training of the base model (RLHF and refusal fine-tuning) · Network-layer abuse: rate limiting, DDoS, account takeover

Non-functional requirements

01How much latency may safety add to each request?

A bounded slice of time-to-first-token: detectors run in parallel and cheap-first, so the input rails add tens of milliseconds — never a second of serial checks.

02The answer streams token by token — when do you check it?

Before display, always: tokens release through a small buffer window, because a token the user has already seen cannot be taken back — retraction after display is an incident, not a control.

03A detector times out mid-request — block or pass?

Decided per surface, in advance: tool execution fails closed (a missed check on a destructive action is unacceptable), plain chat may fail open with a loud alert — never an accident of whichever error path ran.

04How many legitimate users is the pipeline allowed to block?

A tracked budget, not a hope: false-positive rate is measured per rail and per surface, because 0.5% of ten million requests is fifty thousand blocked legitimate users a day.

05A policy change ships — how do you know safety improved?

Every decision is logged with scores and a policy version, and a red-team eval suite plus false-positive tracking gates each new version — coverage is measured, never assumed.

Keep asking — the interview is a conversation

Real interviews probe far more than a tidy list. These are the scope questions that separate candidates who interrogate the problem from those who recite it.

  • Is this wrapping plain chat, or an agent with tools? The tool side changes the whole risk calculus.
  • What latency may safety add — what fraction of time-to-first-token is the budget?
  • Per surface: does a detector failure block the request or let it pass, and who made that call?
  • What are the PII duties — regulated data like health or payments, and reversible masking or irreversible redaction?
  • Who owns the policy, how often does it change, and what gates a new version into production?
01

Unlock the full playbook for LLM Guardrails Pipeline

Numbers, architecture diagram, API and data model, deep dives, expected topics, self-check, whiteboard starter, and common mistakes unlock inside the app.

02

Numbers that force architecture decisions

Locked in the app

03

Architecture path

Locked in the app

04

API and data model

Locked in the app

05

Deep dive directions

Locked in the app

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