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Browse independent practice aligned to xAI: coding, system design, and project practice. Practice progressive coding, concurrency, distributed systems, GPU-oriented reasoning, inference infrastructure, and system design for software and ML engineering roles.
Use these reports to choose what to rehearse, not to predict a fixed loop. Formats vary by role, team, and date; confirm your current process with the recruiter. Frontier Rehearsal is independent and not company-endorsed.
Practice prompt (not a reported interview question): implement a small infrastructure-flavoured function with clear inputs and outputs, then compare your production-oriented solution with an algorithm-first alternative and justify which constraints matter most.
Open permanent linkAccording to candidate reports, xAI's 45-minute backend tech screen is a coding round that asks for something functional, such as an API endpoint or a data-processing function, with some architecture discussion but not a full system-design round.
Open permanent linkCandidate reports describe an xAI coding round delivered in Python and bash over about 45 minutes, focused on day-to-day engineering tasks rather than LeetCode-style puzzles.
Open permanent linkEvidence reviewed . Reports can become stale.
Every question has a public brief with the task, constraints, and follow-ups. Labels describe interactive practice access.
Reported interview periodNot available
A hiring-manager conversation about one run you owned and what you would keep if the team shrank.
Practice focusHiring-manager round. Stay on one run you owned. Name what the run was for and what broke. Say what you kept and what you stopped. Give one measurement from the week after. The interviewer asks who you told first and what you promised not to claim. Do not switch runs.
Reported interview periodNot available
What you would cut if the team lost half its people.
Practice focusHiring-manager round. Half the team is gone next month. Stay on one project. First, list the work you stop and the work you keep, with the reason for each. Then the interviewer asks who you tell first and what you say in the first minute. Include the sentence, and include one promise you will not make. Then they ask what you would measure two weeks later to know the cut was the right one. Answer with one measurement.
Reported interview periodNot available
Two people edit one note and need to see who wrote the last line.
Practice focusSystem design round. Two people share one scratch pad during a review. Start by listing what must be true: neither person loses a line, and both can point at who wrote the last line. Place the note in one store and give each save a version. Walk the case where both save the same version. Then the network drops the second save: the first person must not think the second line landed. Then add a third reader who only watches. Say what that reader sees, what you store, and what you would not build for a note this small.
Reported interview periodNot available
Explain one result you trust, what would falsify it, and what was not shown.
Practice focusResearch round. Explain one result you trust, in four parts: the claim, the comparison, the evidence, and the limit. The interviewer asks what single observation would make you drop the claim. Answer with that observation, not a general doubt. Then they ask what the authors did not show. Name one missing comparison. Then they ask whether you would ship a product on this result today. Answer yes or no, and the reason is the falsifier you already named.
Reported interview periodNot available
Build a map whose values survive a process crash. A memory-only map does not meet the contract.
Practice focusget returns the stored value or nothing. put stores a pair and must reach disk before it returns. Startup reads the file and rebuilds the map. A torn or partial final line is ignored. Requirements - Part one is an append-only log. Each put adds one line. Startup replays the file. Never rewrite a line in place. - An update of an existing key appends a newer line. Replay keeps the last complete line for that key. - A second process that opens the same path must see committed values. - Part two is compaction.…
Reported interview periodNot available
Store sequences of integers so a shared beginning occupies one path. A plain trie uses one node per integer. Here, a run of nodes that each have only one child is stored as one edge.
Practice focusRequirements - Insert shares an edge when two sequences start the same way. A sequence with nothing in common gets its own branch. - Inserting a shorter sequence after a longer one must cut the long edge. - To cut an edge, walk until the new sequence disagrees. The shared head stays on the parent edge. The old tail becomes one child. The new tail becomes another. - A disagreement on the first integer splits that edge into a one-integer head plus two children. - Exact membership is true only for a sequence that was inserted, not for a proper head of one.…
Reported interview periodNot available
Sketch a pipeline that turns a script into shots, frames, audio, and a cut. Name which agent owns each stage. The hard part is consistency: characters, places, and props must hold across many scenes. Pacing is …
Practice focusRequirements - Use a scene record, character sheets, and a continuity tracker as shared memory. - Split the work into a director that turns a script into a shot list, a continuity agent that keeps a vector per character and prop, a renderer that calls a video model conditioned on both, and an editor that reviews cuts and pace. - Inside one clip, rely on the video model to keep a subject that leaves and re-enters the frame. Do not rebuild that part.…
Reported interview periodNot available
Compute the product of two matrices on a group of devices, two ways, and compare both results with a product computed on one device.
Practice focusRequirements - The device count divides both dimensions. One device is the local product. - Data-parallel: each device multiplies its row slice of the left matrix by the full right matrix and sends that block to rank zero, which stacks the rows. - Sharded: the left matrix is split by rows and the right matrix by columns. Over as many rounds as there are devices, each device passes its right-hand shard to the neighbor and adds that partial into the matching columns of the piece it keeps. - The communicator is a set of blocking queues.…
Reported interview periodNot available
Prepare one project story and one reason for the role. The project story is five to eight minutes. Open on a constraint and the choice you made.
Practice focusRequirements - State why you chose that approach, what you turned down, and what you measured. - Lead with the technical choice, not a business result. - Be ready for a redirect to recent work, a deeper bottleneck, or an option you did not use. - The motivation names a real direction you can contribute to, tied to a skill you have already used. - Keep two depths ready: the system shape, and the kernel or model detail. Pick the depth the conversation asks for. - Keep a short reset so a redirect does not lose the thread. Review checklist 1.…
Reported interview periodNot available
Explain why a high-ownership role fits you using one project where you found an unowned problem, chose a direction, and delivered a measurable result. State the boundary of your authority and when you asked for…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Walk through a project where scale exposed a bottleneck. Cover the workload, the measured limit, your model of the bottleneck, the intervention you owned, and the evidence that the limit moved.
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Design a gateway for low-latency model inference across several model versions and accelerator pools. Include admission control, routing, batching, deadlines, retries, overload behavior, observability, and safe…
Practice focusPreparation - Write the user or stakeholder, the constraint, and the decision in one sentence each. - Choose one measurement or observable fact that can support the answer. - Name one alternative and the reason it was not selected. Review checklist 1. Did I state the concrete constraint before describing the solution? 2. Did I separate my own decision and work from the team's work? 3. Did I name evidence or a measurement rather than relying on confidence? 4. Can I answer every follow-up without changing the original facts? Staged follow-ups 1.…
Reported interview periodNot available
Ten people store one score per run and look at which run is ahead this week.
Practice focusSystem design round. Ten people record one score per run. Say what a week means and what a missing score shows. Walk the write and the read. A score arrives twice for the same run. Keep the first. Stop when the board can say this week is still open.
Reported interview periodNot available
Where a design failed after launch, what you measured, and what you changed.
Practice focusProject round. One system, after launch. Start with the design you intended. Then the failure, including who felt it. Then the measurement, including the unit and the window. Then the change. The interviewer asks what you left alone and why. Answer with one thing you refused to change. Then they ask how you would know the failure had returned. Point at the same measurement. Do not switch projects.
Reported interview periodNot available
Model an eight-by-eight board. Each piece is one side's, and each piece is regular or king. There is no hidden grader. The work is the data model and the method boundaries.
Practice focusRequirements - A move check confirms the piece belongs to the player, the destination is empty, the step is diagonal, and the direction matches the piece type. - A capture jumps an opposing piece and may continue in a chain. - A piece that reaches the far row becomes a king. - The game ends when the opponent has no pieces or no legal move. - Represent the board as a grid of optional pieces. - Say whether each move returns a new board or changes the old one.…
Reported interview periodN/A
Review staged prompts that begin with a small in-memory worker, then introduce retries, duplication, cancellation, and process restarts.
Practice focusState modeling, Idempotency, Retry policy, Failure recovery, Operational reasoning through a written response exercise.
Reported interview periodN/A
Connect motivation and scope to evidence from your work, then handle gaps, priorities, and expectations directly.
Practice focusMotivation, Role fit, Scope, Self-awareness, Questions through a written response exercise.
Reported interview periodN/A
Build a defensible walkthrough of a project from problem framing to architecture, experiments, failures, and outcomes.
Practice focusArchitecture, Experiment design, Debugging, Metrics, Trade-offs through a written response exercise.
Reported interview periodN/A
Design a reproducible registry connecting datasets, evaluator configurations, model outputs, and reviewed results.
Practice focusData lineage, Versioning, Idempotency, Access control, Reproducibility through a written response exercise.
Reported interview periodN/A
Practice aligning a broad research-engineering role with evidence, boundaries, first-quarter priorities, and questions for the manager.
Practice focusRole fit, Prioritization, Scope, Self-awareness, Manager questions through a written response exercise.
Reported interview periodN/A
Prepare a technical project account that connects the initial claim, experiment design, implementation choices, failures, and shipped evidence.
Practice focusProblem framing, Experiment design, Architecture, Debugging, Evidence quality through a written response exercise.
Reported interview periodN/A
Practice making a visible priority call when reliability work and a strategic launch compete for the same team.
Practice focusPrioritization, Trade-offs, Risk, Stakeholder communication, Decision review through a written response exercise.
Reported interview periodN/A
Practice turning a research, product, and infrastructure disagreement into an owned decision without flattening the real risks.
Practice focusDisagreement, Decision rights, Cross-functional leadership, Escalation, Communication through a written response exercise.
Reported interview periodN/A
Build a precise account of a failed technical decision, your personal responsibility, the recovery, and the later behavior that changed.
Practice focusOwnership, Failure analysis, Recovery, Reflection, Trust repair through a written response exercise.