> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pinecone.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Set session instructions

> Set a per-session system prompt on a Pinecone Nexus query to shape how a session answers, layered over the context's default instructions.

A session can carry its own answer instructions, a system prompt that shapes how it answers every turn: the role to take, the tone to use, or how to format the result. These layer on top of a context's [default instructions](https://docs.pinecone.io/guides/nexus/context-design.md#context-default-instructions) rather than replacing them. The context default always applies, and the session prompt adds to it, except where it only repeats the default, which Nexus skips.

You pass `system_prompt` on the query that starts the session, and it stays pinned for the rest of the session.

**1. Start a session with a system prompt**

Pass `system_prompt` alongside `scope` and `ask` on the opening query. These fields are set only when a session starts.

```bash curl theme={null}
curl -fsS -X POST "$NEXUS_BASE_URL/query" \
  -H "Authorization: Bearer $NEXUS_TOKEN" \
  -H 'Content-Type: application/json' \
  -H 'X-Pinecone-Api-Version: 2026-07' \
  -d '{
    "scope": ["company-knowledge"],
    "ask": "What changed in the latest contract?",
    "system_prompt": "Answer as a contracts analyst. Be concise, and cite the clause behind every claim."
  }'
```

The response carries a `session_id` and the query's `id`.

**2. Continue the session**

Reference the previous turn with `previous_query_id`. Follow-up turns keep the system prompt, so you don't resend it, and the context default still applies.

```bash curl theme={null}
curl -fsS -X POST "$NEXUS_BASE_URL/query" \
  -H "Authorization: Bearer $NEXUS_TOKEN" \
  -H 'Content-Type: application/json' \
  -H 'X-Pinecone-Api-Version: 2026-07' \
  -d '{
    "previous_query_id": "qry_...",
    "ask": "Who owns the renewal?"
  }'
```

In the console, open **Advanced options** in the new session composer and set the **System prompt**.