errand-bot 0.2.0

//! errand runs a coding agent from a chat channel, in a sandbox it cannot
//! escape.
//!
//! The command line is what an operator runs: the daemon is one subcommand
//! among several rather than the only thing this program does, because
//! managing what it left on disk is an operator's job and belongs where an
//! operator already is.

use std::collections::BTreeMap;
use std::sync::{Arc, Mutex};

use crate::cli::threads::Deps;
use crate::cli::threads::Project;
use crate::cli::threads::run_threads;
use crate::config::load::{config_path, file_exists, load_config};
use crate::config::schema::Config;
use crate::config::schema::ConfigError;
use crate::log::logger;
use crate::log::now_ms;
use crate::log::{LogValue, fields};
use crate::sandbox::policy::POLICY_FILENAME;
use crate::serve::serve;
use crate::session::disk::tree_bytes;
use crate::session::record::record_dir;
use crate::session::registry::ThreadRegistry;

mod admission;
mod agent;
mod chat;
mod cli;
mod config;
mod daemon;
mod lock;
mod log;
mod memory;
mod provider;
mod sandbox;
mod serve;
mod session;
mod web;

#[cfg(test)]
mod docs;
#[cfg(test)]
mod test_util;

/// The environment an operator's shell hands over.
type Vars = BTreeMap<String, String>;

fn usage(env: &Vars) -> String {
    [
        "usage: errand <command>".to_owned(),
        String::new(),
        "  run                  run the daemon until it is told to stop".to_owned(),
        "  threads [command]    manage remembered threads and their data".to_owned(),
        "  help                 this".to_owned(),
        String::new(),
        format!(
            "the configuration is read from {}",
            config_path(env, |candidate| std::path::Path::new(candidate).exists())
        ),
    ]
    .join("\n")
}

/// Reads the configuration the way every command does.
///
/// The environment goes to the reader as well as to the search, so the list a
/// missing file reports names the places actually looked in. Handing it a
/// blank one, as the TypeScript entry point did, produced a report that
/// ignored `ERRAND_CONFIG` and showed paths relative to a `HOME` that was
/// never read: a description of a search that did not happen.
fn load(env: &Vars) -> Result<Config, ConfigError> {
    let path = config_path(env, file_exists);
    load_config(
        &path,
        |read| std::fs::read_to_string(read),
        env,
        file_exists,
    )
}

/// Pulls a `name = "value"` pair off the front of a grant body, leaving the
/// rest of it.
fn grant_pair<'a>(body: &'a str, name: &str) -> Option<(&'a str, String)> {
    let body = body.trim_start().strip_prefix(name)?;
    let body = body.trim_start().strip_prefix('=')?.trim_start();
    let body = body.strip_prefix('"')?;
    let end = body.find('"')?;
    Some((&body[end + 1..], body[..end].to_owned()))
}

/// The host path of the grant placed at /workspace, which is how a policy
/// names the project it was written for.
fn workspace_grant(policy: &str) -> Option<String> {
    let mut rest = policy;
    while let Some(open) = rest.find('{') {
        let close = rest[open..].find('}')? + open;
        let body = &rest[open + 1..close];
        let (rest_of_grant, path) = grant_pair(body, "path")?;
        let (rest_of_grant, at) = grant_pair(rest_of_grant, "at")?;
        if at == "/workspace" && rest_of_grant.trim().is_empty() {
            return Some(path);
        }
        rest = &rest[close + 1..];
    }
    None
}

/// The project a session worked in, read back from the policy it was run
/// under.
///
/// The policy names the project as the grant placed at the workspace, which
/// is the one thing on disk that still says where the work was. Nothing is
/// guessed at: a policy that does not say returns nothing, and the caller
/// refuses.
fn project_of(state_dir: &str) -> Option<Project> {
    let policy =
        std::fs::read_to_string(std::path::Path::new(state_dir).join(POLICY_FILENAME)).ok()?;
    let path = workspace_grant(&policy)?;
    let name = std::path::Path::new(&path)
        .file_name()?
        .to_string_lossy()
        .into_owned();
    Some(Project { name, path })
}

async fn threads(args: &[String], env: &Vars) -> Result<i32, ConfigError> {
    let config = load(env)?;
    let log = logger();
    let registry = Arc::new(Mutex::new(ThreadRegistry::new(
        ThreadRegistry::path_for(&config.state_dir),
        log,
    )));
    registry.lock().expect("the registry lock").load();

    Ok(run_threads(
        args,
        &Deps {
            registry,
            size_of: Arc::new(|state_dir| Box::pin(async move { tree_bytes(&state_dir) })),
            remove: Arc::new(|state_dir| {
                Box::pin(async move {
                    // The record sits beside the state directory, so removing
                    // a thread has to take it too or the transcript outlives
                    // what it describes.
                    tokio::fs::remove_dir_all(&state_dir)
                        .await
                        .map_err(|error| error.to_string())?;
                    let _ = tokio::fs::remove_dir_all(record_dir(&state_dir)).await;
                    Ok(())
                })
            }),
            state_root: config.state_dir,
            project_of: Arc::new(|state_dir| Box::pin(async move { project_of(&state_dir) })),
            write: Arc::new(|line| println!("{line}")),
            now: Arc::new(now_ms),
        },
    )
    .await)
}

/// Runs the daemon, turning the failures an operator can act on into an exit
/// code and one line rather than a stack trace.
async fn run(env: &Vars) -> i32 {
    let log = logger();
    let config = match load(env) {
        Ok(config) => config,
        Err(error) => {
            log.error(
                "the daemon failed to start",
                &fields([("detail", LogValue::from(format!("ConfigError: {error}")))]),
            );
            return 1;
        }
    };
    serve(config, log).await.code()
}

fn main() -> std::process::ExitCode {
    let env: Vars = std::env::vars_os()
        .map(|(key, value)| {
            (
                key.to_string_lossy().into_owned(),
                value.to_string_lossy().into_owned(),
            )
        })
        .collect();
    let args: Vec<String> = std::env::args().skip(1).collect();

    let runtime = tokio::runtime::Builder::new_multi_thread()
        .enable_all()
        .build()
        .expect("a tokio runtime is always buildable");

    match runtime.block_on(dispatch(args, env)) {
        Ok(code) => std::process::ExitCode::from(u8::try_from(code).unwrap_or(1)),
        Err(error) => {
            // A configuration problem is the operator's to fix, so it is
            // printed as itself rather than as a stack trace.
            eprintln!("ConfigError: {error}");
            std::process::ExitCode::FAILURE
        }
    }
}

async fn dispatch(args: Vec<String>, env: Vars) -> Result<i32, ConfigError> {
    let Some(command) = args.first().cloned() else {
        println!("{}", usage(&env));
        return Ok(2);
    };
    match command.as_str() {
        "run" => Ok(run(&env).await),
        "threads" => threads(&args[1..], &env).await,
        "help" | "--help" => {
            println!("{}", usage(&env));
            Ok(0)
        }
        other => {
            eprintln!("there is no command called {other}");
            eprintln!("{}", usage(&env));
            Ok(2)
        }
    }
}