agent-harness 0.1.0

//! The harness registry — an **open** builder so consumers compose their
//! own set of harnesses (the built-ins *and/or* their own custom
//! `impl Harness`), plus convenience constructors over the built-in
//! adapters for hosts that just want "all of them".
//!
//! This is the extensibility seam: a third party adds a provider by
//! implementing [`Harness`](crate::Harness) in their own crate and calling
//! [`Registry::register`] — no fork of this crate required.

use crate::{Harness, HarnessInfo};
#[cfg(feature = "bob")]
use crate::Bob;
#[cfg(feature = "claude")]
use crate::Claude;
#[cfg(feature = "codex")]
use crate::Codex;

/// The identifier used when the caller doesn't pick one — the bob adapter,
/// the conventional default. (A literal so it's available even in builds
/// that compile without the `bob` feature; hosts override as needed.)
pub const DEFAULT_HARNESS_ID: &str = "bob";

/// An open set of harnesses. Build it with the ones you want — the
/// built-ins (`Bob`/`Claude`/`Codex`) and/or your own:
///
/// ```no_run
/// use harness::Registry;
/// let reg = Registry::new()
///     .register(harness::Bob::new());
///     // .register(MyCustomHarness::new())   // your own impl Harness
/// assert!(reg.by_id("bob").is_some());
/// ```
#[derive(Default)]
pub struct Registry {
    harnesses: Vec<Box<dyn Harness>>,
}

impl Registry {
    /// An empty registry.
    pub fn new() -> Self {
        Self::default()
    }

    /// Add a harness. Chainable. Registration order is preserved (it's the
    /// UI display order; the first registered is the conventional default).
    pub fn register(mut self, harness: impl Harness + 'static) -> Self {
        self.harnesses.push(Box::new(harness));
        self
    }

    /// Resolve a harness by its [`HarnessInfo::id`].
    pub fn by_id(&self, id: &str) -> Option<&dyn Harness> {
        self.harnesses
            .iter()
            .map(Box::as_ref)
            .find(|h| h.info().id == id)
    }

    /// Metadata for every registered harness, in registration order.
    pub fn catalog(&self) -> Vec<HarnessInfo> {
        self.harnesses.iter().map(|h| h.info()).collect()
    }

    /// The ids of every registered harness, in registration order.
    pub fn ids(&self) -> Vec<String> {
        self.harnesses.iter().map(|h| h.info().id).collect()
    }
}

/// A [`Registry`] of the built-in adapters compiled into this build
/// (bob / claude / codex), in display order.
pub fn default_registry() -> Registry {
    #[allow(unused_mut)]
    let mut reg = Registry::new();
    #[cfg(feature = "bob")]
    {
        reg = reg.register(Bob::new());
    }
    #[cfg(feature = "claude")]
    {
        reg = reg.register(Claude::new());
    }
    #[cfg(feature = "codex")]
    {
        reg = reg.register(Codex::new());
    }
    reg
}

/// Resolve a *built-in* harness by id, as an owned box — convenience for
/// hosts that look one up per call. Returns `None` for an unknown id.
pub fn harness_by_id(id: &str) -> Option<Box<dyn Harness>> {
    let _ = id;
    #[cfg(feature = "bob")]
    {
        if id == crate::BOB_HARNESS_ID {
            return Some(Box::new(Bob::new()));
        }
    }
    #[cfg(feature = "claude")]
    {
        if id == crate::CLAUDE_HARNESS_ID {
            return Some(Box::new(Claude::new()));
        }
    }
    #[cfg(feature = "codex")]
    {
        if id == crate::CODEX_HARNESS_ID {
            return Some(Box::new(Codex::new()));
        }
    }
    None
}

/// Metadata for every built-in harness — the payload the UI picker renders.
pub fn harness_catalog() -> Vec<HarnessInfo> {
    default_registry().catalog()
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        CredentialSpec, HarnessCapabilities, HarnessReadiness, InstallCallback, RunCallback,
        RunHandle, RunRequest,
    };

    #[test]
    fn default_registry_lists_bob_claude_codex_in_order() {
        assert_eq!(default_registry().ids(), vec!["bob", "claude", "codex"]);
        assert_eq!(default_registry().catalog()[0].id, DEFAULT_HARNESS_ID);
    }

    #[test]
    fn harness_by_id_resolves_builtins_and_rejects_unknown() {
        assert!(harness_by_id("bob").is_some());
        assert!(harness_by_id("claude").is_some());
        assert!(harness_by_id("codex").is_some());
        assert!(harness_by_id("nope").is_none());
    }

    #[test]
    fn capabilities_match_each_adapter_and_back_credential_required() {
        let caps = |id: &str| harness_by_id(id).unwrap().info().capabilities;

        let bob = caps("bob");
        assert!(bob.credential_required && bob.previews_edits);
        assert!(bob.models.is_empty() && !bob.supports_effort && !bob.supports_max_turns);
        assert_eq!(
            bob.credential_required,
            harness_by_id("bob").unwrap().credential().required
        );

        let claude = caps("claude");
        assert!(!claude.credential_required && !claude.previews_edits);
        assert!(!claude.models.is_empty() && !claude.allows_custom_model);
        assert!(claude.supports_max_turns && !claude.supports_effort);

        let codex = caps("codex");
        assert!(!codex.credential_required && !codex.previews_edits);
        assert!(codex.allows_custom_model && codex.supports_effort && !codex.supports_max_turns);

        assert!(claude.supports_login && codex.supports_login && !bob.supports_login);
    }

    // A third-party / custom provider — proves the registry is open: this
    // type lives "outside" the built-ins yet registers + resolves the same.
    struct Acme;
    impl Harness for Acme {
        fn info(&self) -> HarnessInfo {
            HarnessInfo {
                id: "acme".to_owned(),
                display_name: "Acme".to_owned(),
                description: "A custom third-party harness.".to_owned(),
                requires_install: false,
                capabilities: HarnessCapabilities {
                    credential_required: false,
                    previews_edits: false,
                    models: Vec::new(),
                    allows_custom_model: true,
                    supports_effort: false,
                    supports_max_turns: false,
                    supports_login: false,
                },
            }
        }
        fn readiness(&self) -> HarnessReadiness {
            HarnessReadiness {
                harness_id: "acme".to_owned(),
                ready: true,
                installed: true,
                version: None,
                auth_configured: true,
                error: None,
                details: serde_json::Value::Null,
            }
        }
        fn install(&self, _on_event: InstallCallback) -> Result<(), crate::HarnessError> {
            Ok(())
        }
        fn run(
            &self,
            _req: RunRequest,
            _on_event: RunCallback,
        ) -> Result<RunHandle, crate::HarnessError> {
            // A real API-backed harness would call its HTTP endpoint here and
            // emit RunEvents through `on_event`; the dummy never runs.
            Err(crate::HarnessError::Other(
                "acme: run not implemented in test".to_owned(),
            ))
        }
        fn credential(&self) -> CredentialSpec {
            CredentialSpec {
                label: "Acme key".to_owned(),
                keychain_service: "acme".to_owned(),
                keychain_account: "ACME_API_KEY".to_owned(),
                required: false,
            }
        }
    }

    #[test]
    fn custom_harness_registers_and_resolves_alongside_builtins() {
        let reg = Registry::new().register(Bob::new()).register(Acme);
        assert!(reg.by_id("bob").is_some());
        assert!(reg.by_id("acme").is_some(), "custom harness must resolve");
        assert_eq!(reg.ids(), vec!["bob", "acme"]);
    }
}