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Xai·Software Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

xAI SWE interview dropped me into a large, half-finished LLM/agentic codebase and told me to figure out what a missing function was supposed to do and then implement it. No test cases, no input/output specs, just code reading and reasoning. Unusual format compared to anything I'd done before.

Questions Asked (1)

Q1

Given a large, partially implemented LLM/agentic codebase with no test cases or explicit specs, identify what a missing function is supposed to do by reading the surrounding code and then implement it correctly.

Adaptability & AmbiguityTechnical Trade-offsAPI & Integrations
Author's notes

This was not what I expected.

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AI HintsAI Generated

Suggested Approach

Walk through the surrounding code to infer the missing function's contract from call sites, data flow, and naming conventions, then implement it with defensive checks and validate against a quick mental or actual test. Emphasize how you handle ambiguity by forming and testing hypotheses about the function's purpose.

Pro tip: Before writing any code, articulate your assumptions about the function's inputs, outputs, and side effects, and note how you would verify them—this shows structured thinking and reduces risk in ambiguous situations.

1. Map the call sites

Find all places where the missing function is called and note the arguments passed, return values used, and any error handling around the calls.

2. Trace data flow and dependencies

Follow the data from inputs to outputs through the surrounding code to understand what transformations or side effects the function must perform.

3. Infer the contract

Based on naming, comments, and usage patterns, define the function's expected signature, return type, and behavior under edge cases.

4. Implement with defensive coding

Write the function to match the inferred contract, adding assertions or logging for ambiguous cases and handling potential errors gracefully.

5. Validate and iterate

Create a minimal test or use existing code paths to verify the implementation, and refine based on any discrepancies or new insights.

Key Points to Mention

  • Reading call sites and usage patterns to deduce function purpose
  • Using naming conventions, comments, and type hints as clues
  • Tracing data flow and dependencies to understand required transformations
  • Forming and testing hypotheses about the function's contract
  • Implementing with defensive checks and clear error handling
  • Validating the implementation through targeted tests or manual execution

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.