What customer rounds look like, and the core moves

One candidate wrote on Hacker News, in August 2019, that a Stripe interview for a “forward-deployed/field engineer” role was a one-hour role-play that wanted “a nuanced strategy, down to SOAP vs REST with timelines and specific commitments,” and that it “went horribly.” ^[1]Source 1Hacker News comment by eldavido on 'Lessons from Stripe'PublisherHacker NewsSource typecandidate comment on Hacker News In a July 2026 Blind thread, a commenter described problem-discovery and scoping rounds as “roleplaying with a fake client, uncovering their actual problem (not just what they say it is), and proposing a technical solution on the fly”; the comment names no company for that round. ^[2]Source 2FDE Interview Prep QuestionPublisherBlindSource typecandidate report on Blind Coming up: the formats, our rubric’s seven moves, a role-play using them all, and the close.

Formats candidates report: CTO role-plays, pitches, kickoff calls and demos

Know the shapes others met, so no persona surprises you. Each rests on one person’s post.

• One candidate posted on Blind, in July 2026, that the System Architecture round of their Google FDE (L4) loop was “structured as a role-play exercise,” with the interviewer acting as a company’s CTO. ^[3]Source 3FDE Interview Experience at Google (L4)PublisherBlind (teamblind.com)Source typecandidate report on Blind
• In a Blind thread titled “Is Google FDE interview same as SWE?”, a commenter who named no company or role described, in July 2026, consulting with a CTO on building agents, and added in August that they went below high-level orchestration to “prompts, state machines, retries, handling hallucinations.” ^[4]Source 4Is Google FDE interview same as SWE?PublisherBlind (teamblind.com)Source typecandidate report on Blind
• One candidate’s report on Aced, for a Cognition FDE role and dated April 2026, says the final rounds “felt like simulated customer work: one on ones, executive pitches, and a fake-company case.” ^[5]Source 5Cognition AI Forward Deployed Engineer Interview ExperiencePublisherAced (formerly Exponent)Source typecandidate’s personal write-up
• In a Kong take-home brief that one candidate posted on GitHub in September 2026, “Your interviewer will play a customer stakeholder” at a live kickoff call. ^[6]Source 6Kong PS / Forward Deployed Engineer — Take-Home ExercisePublisheralexscottan (GitHub)Source typecandidate’s take-home repository In a HappyRobot brief one candidate posted in June 2026, you present a proof of concept to “a customer (played by the interviewer).” ^[7]Source 7FDE Technical Challenge: Inbound Carrier Sales (PDF)PublisherIanDalton (GitHub)Source typecandidate’s take-home repository

What varies is the persona, the length, and how deep the design goes: in the Stripe and agent reports, down to protocols and retries. A customer round can be a design round with a person in it.

Before a role-play starts, ask once, out of character: “Who am I to you: your vendor’s engineer or a consultant? How long do we have? Do you want a design by the end?” Then stay in character until the interviewer drops it. That opening is our method.

What employers publish: customer-framed formats, not role-plays

No careers page or posting we read describes a round where an interviewer plays a customer. Palantir’s Getting Hired page organizes its prep guides around engineering competencies, and none is a customer role-play. ^[8]Source 8Palantir Careers | Getting HiredPublisherPalantirSource typecompany hiring page Some employers, as of September 2026, describe formats that could become a customer conversation: a demo of what you built at Roboflow and, in an engineering onsite that is not an FDE round, at Sierra; a case study and a panel with stakeholders at Attio; an onsite “real life” experience at Rubie. ^{[9, 10, 11, 12]}Source 9Forward Deployed Engineer @ RoboflowPublisherRoboflow (Ashby job posting)Source typecompany job postingSource 10The AI-native interviewPublisherSierraSource typecompany blogSource 11Forward Deployed GTM Engineer @ AttioPublisherAttio (Ashby job posting)Source typecompany job postingSource 12Forward Deployed Engineer @ RubiePublisherRubie (Ashby job posting)Source typecompany job posting

So ask your recruiter, word for word: “Is any round run as a conversation with someone playing a customer, and will I have to write anything to a customer?”

Written customer tasks

Expect a customer email as well as a call. Ethyca’s own take-home for a Forward Deployed Privacy Engineer has you reproduce a customer’s API error, then write that customer an email. ^[13]Source 13Ethyca Technical Challenge -- Forward Deployed Privacy Engineer (FDPE)PublisherEthyca (GitHub)Source typecompany website One commenter in a thread about Salesforce’s Agentforce FDE role reported, in August 2026, an assessment task to write an email to a customer with unrealistic demands about shipping an AI system within a week. ^[14]Source 14Forward Deployed Engineer (Agentforce) (comment by u/joemons)PublisherReddit r/SalesforceCareersSource typecandidate report on Reddit In an r/csMajors thread about Palantir’s Forward Deployed Enablement Engineer, Customer Success role, one commenter reported, in May 2025, a written test answered as emails to a customer; another, in December 2025, naming no role, reported finding the error in a customer’s code, then answering support tickets. ^{[15, 16]}Source 15Has Anyone Interviewed for Palantir's Forward Deployed Enablement Engineer - Customer Success Role? (comment by u/potatotogold)PublisherReddit r/csMajorsSource typecandidate report on RedditSource 16Has Anyone Interviewed for Palantir's Forward Deployed Enablement Engineer - Customer Success Role? (comment by u/FickleTranslator3387)PublisherReddit r/csMajorsSource typecandidate report on Reddit

The seven moves, and the words for each

Our rubric scores seven moves. One prep site, Aced (formerly Exponent), lists five “strong patterns” for client rounds, from ownership language to no unkeepable promises, and cites no company or candidate source. ^[17]Source 17Forward Deployed Engineer Interview: The Definitive 2026 Guide (FDE)PublisherAced (formerly Exponent)Source typeinterview prep site We adopt them as our method, merging ownership and promises, and add structure, the technical proposal (reported rounds can end in a design) and clarity.

Diagnosis and commitments are gates in our rubric, so a strong average can’t hide a weak score on either; the other moves are weighted, and a zero on any of them still means Not yet.

• Diagnosis before solution, a gate. Say “Before I suggest anything, what happens on Friday if this isn’t fixed?”, not “Got it, we’ll fix that.” Ramp’s blog calls “always be scoping” the main FDE mantra. ^[18]Source 18Forward Deployed EngineeringPublisherRamp Builders (engineering blog)Source typecompany blog
• Structures the conversation. Say “Can I take a few minutes to understand, then suggest a way forward?”, and later “Let me check I have it.” Palantir tells onsite candidates to talk through how they plan to approach a problem. ^[8]Source 8Palantir Careers | Getting HiredPublisherPalantirSource typecompany hiring page
• Technical solution framing. Say “Here’s what I think is happening, and how I’ll check it today,” not “We’ll look at the architecture and get back to you.” Palantir’s page on open-ended questions advises “a functioning idea first.” ^[19]Source 19Palantir Careers | Navigating Open-Ended QuestionsPublisherPalantir TechnologiesSource typecompany hiring page
• Options and trade-offs. Say “Each option has a cost. I recommend this one, and here’s what you give up,” not one plan dressed up as a choice. The same page advises articulating “the alternatives and trade-offs.” ^[19]Source 19Palantir Careers | Navigating Open-Ended QuestionsPublisherPalantir TechnologiesSource typecompany hiring page
• Ownership and calibrated commitments, a gate. Say “I’ll have it in staging this afternoon,” not “We’ll look into it.” Palantir’s US Government FDSE posting, as of September 2026, compares the job, not the interview, to a startup CTO’s, with end-to-end ownership. ^[20]Source 20Forward Deployed Software Engineer - US Government (Washington, D.C.) - Palantir on LeverPublisherPalantir Technologies (Lever)Source typecompany job posting Promising only what you control is our method.
• Acknowledgment and de-escalation. Name what the customer is right about before you disagree: “You’re right that this can’t run into a promotion weekend,” not “I understand your frustration.” That order is our method.
• Clarity for the audience. Say “Short version first,” then the decision, in the customer’s words. Ramp’s blog gives, as example interview feedback, a candidate whose clarity “would make me excited to have them leading a meeting with a customer.” ^[18]Source 18Forward Deployed EngineeringPublisherRamp Builders (engineering blog)Source typecompany blog

None of those employer statements is about customer rounds.

The moves in one short exchange

Read the tags, then cover them and name each move. You are the engineer at the vendor whose assistant books a regional grocer’s deliveries. Its operations director opens with a demand and a deadline.

Director: Your assistant keeps giving our customers the wrong delivery windows. Fix it by Friday.

You (structure): Can I take a few minutes to understand what’s happening, then suggest a way forward? I’d like us to leave with a plan we both agree on.

You (diagnosis): What happens on Friday?

Director: Our promotion weekend starts. Delivery orders roughly double.

You (diagnosis): When did it start, and what happens to a customer who gets a wrong window?

Director: Last Tuesday, when we added evening slots. They wait at home, then call the store.

You (diagnosis): Which windows go wrong: any time of day, or some more than others?

Director: The evening ones. Mostly booked the same day.

You (diagnosis): When one’s wrong, does the van come late, or was the slot already full?

Director: Full. The store says there was never room.

You (acknowledgment): So customers stayed in for deliveries that weren’t coming, and your store managers took the calls. You’re right that this can’t run into a promotion weekend.

You (structure): Let me check I have it. Same-day evening slots are sold when they’re already full, customers wait and call stores, and the promotion multiplies both. Is that right?

Director: Yes. And my store managers are furious.

You (diagnosis): What do you need to tell them today?

Director: That it’s handled, and what to say to customers who call.

You (ownership): I’ll send you a three-line note for them by two o’clock.

You (technical framing): Our assistant reads open windows from your dispatch system’s overnight export. My guess for why only evenings fail: daytime has spare vans, so a stale list rarely offers a full slot, but evening has few, so it sells out after the export. I’ll confirm in the logs today. If I’m right, the real fix is reading each window live from your slot API.

You (options and trade-offs): Each option has a cost. A: stop offering same-day evening slots this weekend. It’s a config change we can reverse in a minute; the cost is lost evening bookings. B: keep them, and your dispatch team exports every quarter hour. That narrows the gap without closing it, and needs your dispatch team today. C: read live from the slot API. That’s the right fix, but it needs read access and a load test at promotion volume, so it lands after the weekend. I recommend A now and C next week. If lost bookings cost you more than the calls, pick B. Which matters more this weekend?

Director: The calls. Go with A.

You (ownership and commitment): A is in staging this afternoon, and in production tomorrow morning once your team has checked it. I’m on call Friday to Sunday: if a store sees a wrong window, they call me, and I switch that slot type off within the hour. For C, I need your dispatch lead to give me read access by Friday. I won’t promise zero wrong windows this weekend. I’ll check last week’s logs and tell you tonight whether any daytime windows went wrong too.

Clarity is the untagged move: short sentences in her words. The playback lets her correct you before you propose. The question about her store managers is the difference between fixing her system and fixing her week. In our rubric, uncovering that hidden agenda and addressing it is what lifts diagnosis to the top level.

The proposal came from the diagnosis: evening slots fail full, not late, which points to data older than the bookings. The complaint named the assistant; the likely cause is a nightly file. Check the data path before you blame or defend the model.

A weak run answers the opening with “Sorry about that, we’ll get a fix out by Friday,” and fails both gates at once.

How a role-play ends: summary, owner, date

End every customer conversation on the four-part close: what we agreed, who does what, by when, and what is still open.

You (structure: the close): To recap. We agreed to stop same-day evening slots through the weekend, and switch to the live slot API next week. You get the store managers’ note by two. I ship the change to staging today and production tomorrow morning, after your team checks it, and I’m on call all weekend. Your dispatch lead gets me read access by Friday, so we can load-test next week. Still open: whether daytime windows went wrong; I’ll tell you tonight. I’ll send this in writing within the hour.

Our method ends every role-play on this close, and scores the follow-up email on its own rubric: Decision and summary first; Owners and dates; Accuracy to the conversation; and Tone for the relationship. Send it within the hour: the director forwards it to her boss, who never heard the call. It opens like this:

Subject: Evening delivery windows: plan for the promotion weekend

We agreed to stop same-day evening slots through the weekend and read live slot data from next week.

Me: store-manager note by two today; change live tomorrow morning after your team’s check; on call all weekend. Your dispatch lead: slot API access by Friday.

Now tell the CTO her integration is three weeks late, out loud, using each move once: an agenda, the late date up front, a question about what the original date protected, acknowledgment, a playback, options with a recommendation she can reject, a dated commitment and the four-part close. Record it and tick the two gates.

Keep going. The reply to a customer’s unrealistic demands is free, with a model answer: the written half. Pro opens the rest of this module, including sorting a “your AI is making things up” complaint into five kinds, each with its own fix; the design round as a CTO role-play; the words that escalate an angry customer; and the follow-up email.