CCARF Practice Question

Paper 4 · Question 11

D3 Claude Code Configuration & Workflows · Paper 4

A fintech company requires that all API response payloads are normalised to snake_case before being logged, and that any file write to the src/api/ directory is automatically linted. They want these enforcements to be deterministic and not rely on the model remembering instructions. Which hook configuration achieves both requirements?

• A.A PreToolUse hook on file writes that runs the linter before the write completes, and a PostToolUse hook on API response handling that normalises field names to snake_case
• B.A PostToolUse hook on file writes to src/api/ that runs the linter on the created file, and a PostToolUse hook on data processing that normalises response payloads to snake_case
• C.Add both requirements to CLAUDE.md with clear examples, and add a PreToolUse hook that reminds the model about these rules before each tool call
• D.A PreToolUse hook that blocks any file write to src/api/ unless the file has already been linted, and a PreToolUse hook that blocks API calls unless snake_case normalisation is configured

Show answer & explanations

Correct answer: B

A: PreToolUse fires before the tool runs, so there is no file content to lint yet. Linting must happen after the file is written (PostToolUse). The ordering of hooks to actions is incorrect here.

B: Both are PostToolUse hooks because both act on completed outputs. The linter runs after a file write to src/api/ is complete, validating the written content. The normalisation hook processes API response data after it is retrieved, converting fields to snake_case before logging. Both provide deterministic enforcement independent of model instructions.

C: CLAUDE.md instructions and PreToolUse reminders both rely on the model's compliance, which is not deterministic. The requirement explicitly states that enforcement must not depend on the model remembering instructions.

D: PreToolUse blocking assumes the file exists before the write, which is contradictory. You cannot lint a file that has not been written yet. PostToolUse hooks that process output after completion are the correct approach for validation and normalisation.

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