Chat template renderer

Build the transcript, then press Render.

• Every template here is a documented wire format, and the page names its source. That is the whole claim: what you see is what the format's documentation says, not a promise that a specific served model accepts it verbatim.
• Served models often wrap your messages in their own server-side template. Sending this rendered text as a plain user message double-wraps it — these formats are for local engines and prompt debugging, not for chat APIs that already template.
• Token counts use the selected OpenAI encoding. For non-OpenAI formats that is an approximation by construction — their markers are not special tokens in these vocabularies.
• Formats with no system slot (Mistral, Gemma) fold the system message into the first user turn and report the fold — nothing is dropped silently.

• ChatML: The ChatML wire format documented in OpenAI's legacy cookbook examples.
• Llama 2: Meta's documented Llama 2 chat format ([INST] … [/INST] with <<sys>>).
• Llama 3 / 3.1: Meta's documented Llama 3 chat template (<|start_header_id|> … <|eot_id|>).
• Mistral (v3): Mistral's documented [INST] … [/INST] chat format.
• Gemma: Google's documented Gemma turn format (<start_of_turn>user / model).
• Alpaca: Stanford Alpaca's documented prompt format (Instruction / Input / Response).