Added AI settings & AI chat APIs

Ticket: ENT-13241
Signed-off-by: Ihor Aleksandrychiev <ihor.aleksandrychiev@northern.tech>

Author: aleksandrychev

content/api/enterprise-api-ref/ai-chat.markdown

@@ -0,0 +1,117 @@
+---
+layout: default
+title: AI chat API
+---
+
+The AI chat API converts natural language questions into SQL queries for retrieving CFEngine data.
+
+## Send message to AI chat
+
+Converts a question into a SQL query and explanation. The AI chat uses LLM configured via [AI settings][AI settings API].
+
+**URI:** https://hub.cfengine.com/api/ai/text-to-sql
+
+**Method:** POST
+
+**Prerequisites:**
+
+At least one LLM configuration must be created using the [AI settings API][AI settings API#Create AI setting].
+
+**Parameters:**
+
+- **question** _(string)_
+  The question to ask. Required.
+- **history** _(array)_
+  Optional conversation history for context. Array of previous question/answer pairs to maintain conversation context.
+
+**Example request (curl):**
+
+```console
+curl --user <username>:<password> \
+  -X POST \
+  https://hub.cfengine.com/api/ai/text-to-sql \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "question": "Hosts that have SSH port open"
+  }'
+```
+
+**Example request with conversation history:**
+
+```console
+curl --user <username>:<password> \
+  -X POST \
+  https://hub.cfengine.com/api/ai/text-to-sql \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "question": "What about their uptime?",
+    "history": [
+      {
+        "question": "Hosts that have SSH port open",
+        "sql": "SELECT h.hostname, i.values ->> '\''OS'\'' AS os, h.ipaddress, i.values ->> '\''Ports listening'\'' AS open_ports FROM hosts h JOIN inventory_new i ON h.hostkey = i.hostkey WHERE COALESCE(i.values ->> '\''Ports listening'\'', '\''　'\'') ~ '\''(,\\s|^)22(,|$)'\''"
+      }
+    ]
+  }'
+```
+
+**Example response:**
+
+```
+HTTP 200 OK
+{
+  "explanation": "This query lists hosts with SSH port open, including their hostname, OS, IP address, open ports, and uptime in minutes.",
+  "sql": "SELECT h.hostname, i.values ->> 'OS' AS os, h.ipaddress, i.values ->> 'Ports listening' AS open_ports, i.values ->> 'Uptime minutes' AS uptime_minutes FROM hosts h JOIN inventory_new i ON h.hostkey = i.hostkey WHERE COALESCE(i.values ->> 'Ports listening', '\u3000') ~ '(,\\s|^)22(,|$)'",
+  "meta": {
+    "provider": "openai",
+    "model": "gpt-4.1"
+  }
+}
+```
+
+**Output:**
+
+- **explanation**
+  Explanation of what the SQL query does and what data it retrieves.
+- **sql**
+  The generated SQL query that can be executed against the CFEngine reporting database.
+- **meta**
+  Metadata about the LLM used to generate the response.
+  - **provider** - The LLM provider used (e.g., `openai`, `anthropic`, `ollama`).
+  - **model** - The specific model used (e.g., `gpt-4`, `claude-3-opus`).
+
+**Responses:**
+
+| HTTP response code           | Description                                      |
+| ---------------------------- | ------------------------------------------------ |
+| 200 OK                       | Successful response with SQL query               |
+| 400 Bad Request              | Invalid request data or LLM processing error     |
+| 422 Unprocessable Entity     | No LLM configuration found                       |
+
+**Error response examples:**
+
+Missing LLM configuration:
+
+```
+HTTP 422 Unprocessable Entity
+Add an LLM configuration before using the chat.
+```
+
+Invalid request:
+
+```
+HTTP 400 Bad Request
+{
+  "success": false,
+  "errors": [
+    {
+      "field": "[question]",
+      "message": "This value should be of type string."
+    }
+  ]
+}
+```
+
+## Security considerations
+
+The AI chat does not execute SQL queries automatically - it only generates them. You must execute the queries separately through the [Query API][Query REST API#Execute SQL query]. AI does not have access to any
+of your data, unless this data will be sent to the chat by a user.