Codestral Fill-in-the-Middle (FIM) Prompting

Codestral is fluent in 80+ programming languages and features a dedicated Fill-in-the-Middle (FIM) mechanism. To use FIM effectively, pass the code above the cursor as the prompt (prefix: function definition and docstring) and the code below the cursor as the suffix (how the function is invoked), using temperature: 0.2 and stop: ['```'] for consistent code.

FIM Config (codestral-latest): temperature=0.2, max_tokens=8000, stop=["```"]
prompt (Prefix): "def parse_iso_timestamp(ts: str) -> datetime:\n \"\"\"Parse ISO-8601 string with timezone validation.\"\"\"\n"
suffix (Suffix): "\n return parsed_dt\n\nassert parse_iso_timestamp('2026-10-01T12:00:00Z').year == 2026"