Payment Flow (x402 Protocol)

First request (no PAYMENT-SIGNATURE) -> 402 Payment Required with requirements JSON
Client signs (EIP-712) -> PAYMENT-SIGNATURE
Retry with PAYMENT-SIGNATURE -> Server settles and returns response

With @springmint/x402-payment or x402-sdk-go, payment is automatic.

When to Use

Use Case	Skill	Why
Quick factual answer (raw context)	`llm-context`	Single search, returns raw context for YOUR LLM
Fast AI answer with citations	`answers` (single-search)	streaming, citations
Thorough multi-search deep research	`answers` (research mode)	Iterative deep research, synthesized cited answer

This endpoint (/res/v1/chat/completions) supports two modes:

Single-search (default): Fast AI-grounded answer from a single search. Supports enable_citations.
Research (enable_research=true): Multi-iteration deep research with progress events and synthesized cited answer.

Quick Start (cURL)

Blocking (Single-Search)

curl -X POST "https://www.cpbox.io/api/x402/answers" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [{"role": "user", "content": "How does the James Webb Space Telescope work?"}],
    "model": "default",
    "stream": false
  }'

Streaming with Citations (Single-Search)

curl -X POST "https://www.cpbox.io/api/x402/answers" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [{"role": "user", "content": "What are recent breakthroughs in fusion energy?"}],
    "model": "default",
    "stream": true,
    "enable_citations": true
  }'

Research Mode

curl -X POST "https://www.cpbox.io/api/x402/answers" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [{"role": "user", "content": "Compare quantum computing approaches"}],
    "model": "default",
    "stream": true,
    "enable_research": true,
    "research_maximum_number_of_iterations": 3,
    "research_maximum_number_of_seconds": 120
  }'

Using with x402-payment

CLI (AI Agent)

npx @springmint/x402-payment \
  --url https://www.cpbox.io/api/x402/answers \
  --method POST \
  --input '{"messages":[{"role":"user","content":"How does the James Webb Space Telescope work?"}],"model":"default","stream":false}'

Payload/Response

OpenAI-compatible chat.completions JSON + SSE streaming (pass-through).

Two Modes

Feature	Single-Search (default)	Research (`enable_research=true`)
Speed	Fast	Slow
Searches	1	Multiple (iterative)
Streaming	Optional (`stream=true/false`)	Required (`stream=true`)
Citations	`enable_citations=true` (streaming only)	Built-in (in `<answer>` tag)
Progress events	No	Yes (`<progress>` tags)
Blocking response	Yes (`stream=false`)	No

Parameters

Standard Parameters

Parameter	Type	Required	Default	Description
`messages`	array	Yes	-	Single user message (exactly 1 message)
`model`	string	Yes	-	Use `"default"`
`stream`	bool	No	true	Enable SSE streaming
`country`	string	No	"US"	Search country (2-letter country code or `ALL`)
`language`	string	No	"en"	Response language
`safesearch`	string	No	"moderate"	Search safety level (`off`, `moderate`, `strict`)
`max_completion_tokens`	int	No	null	Upper bound on completion tokens
`enable_citations`	bool	No	false	Include inline citation tags (single-search streaming only)
`web_search_options`	object	No	null	OpenAI-compatible; `search_context_size`: `low`, `medium`, `high`

Research Parameters

Parameter	Type	Required	Default	Description
`enable_research`	bool	No	`false`	Enable research mode
`research_allow_thinking`	bool	No	`true`	Enable extended thinking
`research_maximum_number_of_tokens_per_query`	int	No	`8192`	Max tokens per query (1024-16384)
`research_maximum_number_of_queries`	int	No	`20`	Max total search queries (1-50)
`research_maximum_number_of_iterations`	int	No	`4`	Max research iterations (1-5)
`research_maximum_number_of_seconds`	int	No	`180`	Time budget in seconds (1-300)
`research_maximum_number_of_results_per_query`	int	No	`60`	Results per search query (1-60)

Constraints (IMPORTANT)

Constraint	Error
`enable_research=true` requires `stream=true`	"Blocking response doesn't support 'enable_research' option"
`enable_research=true` incompatible with `enable_citations=true`	"Research mode doesn't support 'enable_citations' option"
`enable_citations=true` requires `stream=true`	"Blocking response doesn't support 'enable_citations' option"

Notes for Agent Usage

Use x402-payment to handle the payment handshake automatically, especially for streaming (stream=true).

Response Format

Blocking Response (`stream=false`, single-search only)

Standard OpenAI-compatible JSON:

{
  "id": "chatcmpl-...",
  "object": "chat.completion",
  "choices": [{"message": {"role": "assistant", "content": "The James Webb Space Telescope works by..."}, "index": 0, "finish_reason": "stop"}],
  "usage": {"prompt_tokens": 10, "completion_tokens": 50, "total_tokens": 60}
}

Streaming Response

SSE response with OpenAI-compatible chunks:

data: {"id":"chatcmpl-...","object":"chat.completion.chunk","choices":[{"delta":{"content":"Based on"},"index":0}]}

data: {"id":"chatcmpl-...","object":"chat.completion.chunk","choices":[{"delta":{"content":" recent research"},"index":0}]}

data: [DONE]

Streaming Tags by Mode

Single-Search (with `enable_citations=true`)

Tag	Purpose
`<citation>`	Inline citation references
`<usage>`	JSON cost/billing data

Research Mode

Tag	Purpose	Keep?
`<queries>`	Generated search queries	Debug
`<analyzing>`	URL counts (verbose)	Debug
`<thinking>`	URL selection reasoning	Debug
`<progress>`	Stats: time, iterations, queries, URLs analyzed, tokens	Monitor
`<blindspots>`	Knowledge gaps identified	Yes
`<answer>`	Final synthesized answer (only the final answer is emitted; intermediate drafts are dropped)	Yes
`<usage>`	JSON cost/billing data (included at end of streaming response)	Yes

Usage Tag Format

The <usage> tag contains JSON-stringified cost and token data:

<usage>{"X-Request-Requests":1,"X-Request-Queries":8,"X-Request-Tokens-In":15000,"X-Request-Tokens-Out":2000,"X-Request-Requests-Cost":0.005,"X-Request-Queries-Cost":0.032,"X-Request-Tokens-In-Cost":0.075,"X-Request-Tokens-Out-Cost":0.01,"X-Request-Total-Cost":0.122}</usage>

Use Cases

Chat interface integration: Use this endpoint to get a web-grounded answer payload in OpenAI-compatible format.
Deep research / comprehensive topic research: Use research mode (enable_research=true) for complex questions needing multi-source synthesis (e.g., "Compare approaches to nuclear fusion").
OpenAI SDK drop-in: Same SDK, same streaming format — just change base_url and api_key. Works with both sync and async clients.
Cited answers: Enable enable_citations=true in single-search mode for inline citation tags, or use research mode which automatically includes citations in its answer.

Notes

Timeout: Set client timeout to at least 30s for single-search, 300s (5 min) for research
Single message: The messages array must contain exactly 1 user message
Cost monitoring: Parse the <usage> tag from streaming responses to track costs

Payment Flow (x402 Protocol)

When to Use

Quick Start (cURL)

Blocking (Single-Search)

Streaming with Citations (Single-Search)

Research Mode

Using with x402-payment

CLI (AI Agent)

Payload/Response

Two Modes

Parameters

Standard Parameters

Research Parameters

Constraints (IMPORTANT)

Notes for Agent Usage

Response Format

Blocking Response (stream=false, single-search only)

Streaming Response

Streaming Tags by Mode

Single-Search (with enable_citations=true)

Research Mode

Usage Tag Format

Use Cases

Notes

Blocking Response (`stream=false`, single-search only)

Single-Search (with `enable_citations=true`)

Role	Domain
API Provider	https://www.cpbox.io
Facilitator	https://www.cppay.finance

answers

Answers — AI Grounding

Service URLs

Endpoint (Agent Interface)