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//! Inference on co/core (https://cocore.dev/docs/inference): OpenAI-compatible chat completions at
//! https://cocore.dev/api/v1 through the host's com.fedfork.exec.http.fetch. The module sends no
//! credentials: the host adds them for that origin, a service-auth token it mints from the user's PDS
//! (aud did:web:cocore.dev, lxm dev.cocore.inference.dispatch) or a co/core API key.
use abi::{Call, Event, Handle, Run};
use cocore::{Args, field};
use serde_json::{Value, json};
pub const API: &str = "https://cocore.dev/api/v1";
const MAX_TOKENS: u64 = 1024;
const ONBOARDING: &str = "this account has not connected co/core yet: sign in at https://cocore.dev once, then try again (onboarding_required)";
fn number(args: &Args, key: &str, default: u64) -> Result<u64, String> {
let n = field(args, key).map_or(Ok(default), |v| v.parse().map_err(|_| format!("{key} must be a whole number")))?;
if n == 0 {
return Err(format!("{key} must be at least 1"));
}
Ok(n)
}
/// A JSON field given as itself or as its text (form fields are strings).
fn json_field(args: &Args, key: &str) -> Result<Option<Value>, String> {
match args.get(key) {
None | Some(Value::Null) => Ok(None),
Some(Value::String(s)) if s.trim().is_empty() => Ok(None),
Some(Value::String(s)) => serde_json::from_str(s).map(Some).map_err(|e| format!("{key}: {e}")),
Some(v) => Ok(Some(v.clone())),
}
}
fn truthy(args: &Args, key: &str) -> bool {
matches!(field(args, key).as_deref(), Some("true" | "1" | "yes" | "on"))
}
/// The route: chat/completions, or its private (friends), verified (attested) or probono variant.
fn url(args: &Args) -> Result<String, String> {
match field(args, "route").as_deref() {
None | Some("open") => Ok(format!("{API}/chat/completions")),
Some(r @ ("private" | "verified" | "probono")) => Ok(format!("{API}/{r}/chat/completions")),
Some(r) => Err(format!("route {r}: open, private, verified or probono")),
}
}
fn request(args: &Args) -> Result<Value, String> {
let mut messages = match json_field(args, "messages")? {
None => vec![],
Some(Value::Array(m)) => m,
Some(_) => return Err("messages must be a list of chat messages".into()),
};
if let Some(system) = field(args, "system") {
messages.insert(0, json!({ "role": "system", "content": system }));
}
if let Some(prompt) = field(args, "prompt") {
messages.push(json!({ "role": "user", "content": prompt }));
}
if !messages.iter().any(|m| m["role"] == "user") {
return Err("prompt (or messages with a user message) is required".into());
}
let mut body = json!({
"model": field(args, "model").unwrap_or_else(|| "stub".into()),
"messages": messages,
"max_tokens": number(args, "maxTokens", MAX_TOKENS)?,
"stream": truthy(args, "stream"),
});
for (key, wire) in [("country", "country"), ("minProviderVersion", "min_provider_version"), ("minTrust", "min_trust")] {
if let Some(v) = field(args, key) {
body[wire] = json!(v);
}
}
Ok(body)
}
/// A non-2xx answer as the run's error: co/core's { error: { type, code, message } } envelope.
fn http_error(output: &Value) -> Option<String> {
let status = output["status"].as_u64().unwrap_or(0);
if (200..300).contains(&status) {
return None;
}
let body: Value = serde_json::from_str(output["body"].as_str().unwrap_or_default()).unwrap_or(Value::Null);
let error = &body["error"];
if error["code"] == "onboarding_required" {
return Some(format!("co/core: {ONBOARDING}"));
}
let kind = error["code"].as_str().or(error["type"].as_str()).unwrap_or("error");
let message = error["message"].as_str().map_or_else(|| output["body"].as_str().unwrap_or_default().chars().take(300).collect(), String::from);
Some(format!("co/core HTTP {status} {kind}: {message}"))
}
/// The answer: a chat.completion, or an event stream of chat.completion.chunk folded into one.
fn answer(output: &Value) -> Result<Value, String> {
if let Some(e) = http_error(output) {
return Err(e);
}
let body = output["body"].as_str().unwrap_or_default();
let streamed = output["headers"]["content-type"].as_str().is_some_and(|t| t.starts_with("text/event-stream"));
if !streamed {
let c: Value = serde_json::from_str(body).map_err(|e| format!("co/core answered no JSON: {e}"))?;
let choice = &c["choices"][0];
return Ok(json!({
"text": choice["message"]["content"].as_str().unwrap_or_default(),
"finishReason": choice["finish_reason"],
"toolCalls": choice["message"].get("tool_calls").cloned().unwrap_or(json!([])),
"model": c["model"],
"usage": c["usage"],
"cocore": c.get("x_cocore").cloned().unwrap_or(Value::Null),
}));
}
let (mut text, mut finish, mut usage, mut model, mut cocore) = (String::new(), Value::Null, Value::Null, Value::Null, Value::Null);
let mut tools: Vec<Value> = vec![];
for data in body.replace("\r\n", "\n").split("\n\n").filter_map(|frame| frame.lines().find_map(|l| l.strip_prefix("data:")).map(str::trim)) {
if data == "[DONE]" {
continue;
}
let Ok(chunk) = serde_json::from_str::<Value>(data) else { continue };
if chunk.get("error").is_some() {
return Err(http_error(&json!({ "status": 502, "body": data })).unwrap_or_default());
}
let choice = &chunk["choices"][0];
text.push_str(choice["delta"]["content"].as_str().unwrap_or_default());
// tool calls stream in pieces by index: the name once, the arguments appended
for part in choice["delta"]["tool_calls"].as_array().into_iter().flatten() {
let i = part["index"].as_u64().unwrap_or(0) as usize;
while tools.len() <= i {
tools.push(json!({ "type": "function", "function": { "name": "", "arguments": "" } }));
}
let t = &mut tools[i];
if let Some(id) = part["id"].as_str() {
t["id"] = json!(id);
}
for key in ["name", "arguments"] {
let piece = part["function"][key].as_str().unwrap_or_default();
t["function"][key] = json!(format!("{}{piece}", t["function"][key].as_str().unwrap_or_default()));
}
}
let take = |slot: &mut Value, v: &Value| {
if !v.is_null() {
*slot = v.clone();
}
};
take(&mut finish, &choice["finish_reason"]);
take(&mut usage, &chunk["usage"]);
take(&mut model, &chunk["model"]);
take(&mut cocore, &chunk["x_cocore"]);
}
Ok(json!({ "text": text, "finishReason": finish, "toolCalls": tools, "model": model, "usage": usage, "cocore": cocore }))
}
fn chat_handler(run: Run<Args>) -> Result<Handle, String> {
Ok(match run.event {
Event::Start => {
let mut body = request(&run.args)?;
let headers = json!({ "content-type": "application/json", "accept": if body["stream"] == true { "text/event-stream" } else { "application/json" } });
let url = url(&run.args)?;
if let Some(Value::Object(extra)) = json_field(&run.args, "extra")? {
body.as_object_mut().unwrap().extend(extra);
}
Handle::new().call(Call::http("chat", "POST", &url, headers, Some(body.to_string())))
}
Event::Result { result, .. } => Handle::new().result(answer(&result.into_result()?)?).done(),
_ => Handle::new(),
})
}
/// The public model directory (view: openai, the default; summary or directory).
fn models_handler(run: Run<Args>) -> Result<Handle, String> {
Ok(match run.event {
Event::Start => {
let url = field(&run.args, "view").map_or_else(|| format!("{API}/models"), |v| format!("{API}/models?view={v}"));
Handle::new().call(Call::http("models", "GET", &url, json!({}), None))
}
Event::Result { result, .. } => {
let output = result.into_result()?;
if let Some(e) = http_error(&output) {
return Err(e);
}
Handle::new().result(serde_json::from_str(output["body"].as_str().unwrap_or_default()).map_err(|e| format!("co/core answered no JSON: {e}"))?).done()
}
_ => Handle::new(),
})
}
abi::entries!(chat => chat_handler, models => models_handler);
