supercode-harness 0.4.3

//! P4b (COMPOSABLE-HARNESS-DESIGN.md §5.2 "P4", context-assembly & session-
//! record subset): behavioral tests for the stop-gate hook, the steering
//! queue, the compaction pressure trigger + focus instructions, persisted
//! per-turn usage records, and auto-title — driven end to end with a mock
//! provider, no network, mirroring `agent_loop.rs`'s pattern.

use std::sync::atomic::{AtomicUsize, Ordering};

use async_trait::async_trait;
use supercode_harness::session_title::SessionTitler;
use supercode_harness::{
    Agent, ChatMessage, ChatRequest, Config, Provider, Role, SessionStore, Usage,
};

fn temp_dir(tag: &str) -> std::path::PathBuf {
    let dir = std::env::temp_dir().join(format!(
        "supercode-p4b-{tag}-{}-{}",
        std::process::id(),
        std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_nanos()
    ));
    std::fs::create_dir_all(&dir).unwrap();
    dir
}

// ============================== stop-gate ================================

/// A provider that always answers with plain text (no tool calls), so the
/// loop's idle/stop-gate path fires on every model round-trip.
struct AlwaysFinalProvider {
    calls: AtomicUsize,
}

#[async_trait]
impl Provider for AlwaysFinalProvider {
    async fn complete(
        &self,
        _req: &ChatRequest,
        _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
    ) -> supercode_harness::Result<(ChatMessage, Usage)> {
        let n = self.calls.fetch_add(1, Ordering::SeqCst);
        Ok((
            ChatMessage::assistant(format!("final-{n}")),
            Usage::default(),
        ))
    }
}

#[tokio::test]
async fn stop_gate_default_off_returns_immediately() {
    let config = Config::builder().build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(AlwaysFinalProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    let reply = agent.send("go").await.unwrap();
    assert_eq!(reply, "final-0", "no stop_gate installed: stop immediately");
}

#[tokio::test]
async fn stop_gate_vetoes_once_then_allows_the_second_final_answer() {
    let veto_calls = std::sync::Arc::new(AtomicUsize::new(0));
    let vc = veto_calls.clone();
    let config = Config::builder()
        .stop_gate(Box::new(move |_content: &str| {
            let n = vc.fetch_add(1, Ordering::SeqCst);
            if n == 0 {
                Some("not done yet, keep going".to_string())
            } else {
                None
            }
        }))
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(AlwaysFinalProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    let reply = agent.send("go").await.unwrap();
    assert_eq!(reply, "final-1", "veto forces a second model round-trip");
    assert_eq!(
        veto_calls.load(Ordering::SeqCst),
        2,
        "gate consulted once per would-be-final answer"
    );
    // The veto reason was injected as a real user message in history.
    assert!(agent
        .history()
        .iter()
        .any(|m| m.role == Role::User && m.content.as_deref() == Some("not done yet, keep going")));
}

#[tokio::test]
async fn stop_gate_still_bounded_by_max_iterations_if_it_always_vetoes() {
    let config = Config::builder()
        .max_iterations(3)
        .stop_gate(Box::new(|_: &str| Some("never stop".to_string())))
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(AlwaysFinalProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    let err = agent.send("go").await.unwrap_err();
    assert!(
        matches!(err, supercode_harness::Error::MaxIterations(3)),
        "an always-vetoing gate must not loop forever — bounded by max_iterations: {err:?}"
    );
}

// ============================== steering ==================================

struct AssertingProvider<F> {
    check: F,
}

#[async_trait]
impl<F> Provider for AssertingProvider<F>
where
    F: Fn(&ChatRequest) -> ChatMessage + Send + Sync,
{
    async fn complete(
        &self,
        req: &ChatRequest,
        _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
    ) -> supercode_harness::Result<(ChatMessage, Usage)> {
        Ok(((self.check)(req), Usage::default()))
    }
}

#[tokio::test]
async fn queued_steer_message_delivered_one_at_a_time_and_leftover_persists_for_next_turn() {
    let provider = AssertingProvider {
        check: |req: &ChatRequest| {
            assert!(
                req.messages
                    .iter()
                    .any(|m| m.content.as_deref() == Some("first")),
                "queued steer message must be injected before this request"
            );
            assert!(
                !req.messages
                    .iter()
                    .any(|m| m.content.as_deref() == Some("second")),
                "one-at-a-time mode must not deliver the second queued message yet"
            );
            ChatMessage::assistant("ok")
        },
    };
    let config = Config::builder().build();
    let mut agent = Agent::with_provider(config, Box::new(provider));
    agent.queue_steer("first");
    agent.queue_steer("second");
    let reply = agent.send("go").await.unwrap();
    assert_eq!(reply, "ok");
    assert_eq!(
        agent.queued_steer_count(),
        1,
        "the second steer message stays queued for the next turn"
    );
}

#[tokio::test]
async fn steering_mode_all_drains_every_queued_message_at_once() {
    let provider = AssertingProvider {
        check: |req: &ChatRequest| {
            let combined = req
                .messages
                .iter()
                .rev()
                .find(|m| m.role == Role::User && m.content.as_deref() != Some("go"))
                .and_then(|m| m.content.clone());
            assert_eq!(combined.as_deref(), Some("first\n\nsecond"));
            ChatMessage::assistant("ok")
        },
    };
    let config = Config::builder()
        .steering_mode(supercode_harness::SteeringMode::All)
        .build();
    let mut agent = Agent::with_provider(config, Box::new(provider));
    agent.queue_steer("first");
    agent.queue_steer("second");
    agent.send("go").await.unwrap();
    assert_eq!(
        agent.queued_steer_count(),
        0,
        "All mode drains everything at once"
    );
}

#[tokio::test]
async fn queued_follow_up_message_is_delivered_at_idle_and_continues_the_loop() {
    struct FollowUpProvider {
        calls: AtomicUsize,
    }
    #[async_trait]
    impl Provider for FollowUpProvider {
        async fn complete(
            &self,
            req: &ChatRequest,
            _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
        ) -> supercode_harness::Result<(ChatMessage, Usage)> {
            let n = self.calls.fetch_add(1, Ordering::SeqCst);
            if n == 0 {
                Ok((ChatMessage::assistant("first answer"), Usage::default()))
            } else {
                assert!(
                    req.messages
                        .iter()
                        .any(|m| m.content.as_deref() == Some("follow up question")),
                    "follow-up message must be injected once the loop went idle"
                );
                Ok((ChatMessage::assistant("second answer"), Usage::default()))
            }
        }
    }
    let config = Config::builder().build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(FollowUpProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.queue_follow_up("follow up question");
    let reply = agent.send("go").await.unwrap();
    assert_eq!(reply, "second answer");
    assert_eq!(agent.queued_steer_count(), 0);
}

#[tokio::test]
async fn queued_follow_up_takes_priority_over_a_pending_stop_gate_veto() {
    // A queued follow-up is more input to answer, not a veto of an answer
    // already given — it should be delivered without ever consulting the
    // stop gate for that idle point.
    struct OnceProvider {
        calls: AtomicUsize,
    }
    #[async_trait]
    impl Provider for OnceProvider {
        async fn complete(
            &self,
            _req: &ChatRequest,
            _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
        ) -> supercode_harness::Result<(ChatMessage, Usage)> {
            let n = self.calls.fetch_add(1, Ordering::SeqCst);
            Ok((
                ChatMessage::assistant(format!("answer-{n}")),
                Usage::default(),
            ))
        }
    }
    let gate_calls = std::sync::Arc::new(AtomicUsize::new(0));
    let gc = gate_calls.clone();
    let config = Config::builder()
        .stop_gate(Box::new(move |_: &str| {
            gc.fetch_add(1, Ordering::SeqCst);
            None
        }))
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(OnceProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.queue_follow_up("one more thing");
    let reply = agent.send("go").await.unwrap();
    assert_eq!(reply, "answer-1");
    assert_eq!(
        gate_calls.load(Ordering::SeqCst),
        1,
        "stop_gate is skipped entirely on the idle point where a follow-up was delivered instead"
    );
}

// ============================ compaction pressure ==========================

struct EchoLongProvider;

#[async_trait]
impl Provider for EchoLongProvider {
    async fn complete(
        &self,
        _req: &ChatRequest,
        _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
    ) -> supercode_harness::Result<(ChatMessage, Usage)> {
        Ok((ChatMessage::assistant("x".repeat(3000)), Usage::default()))
    }
}

#[tokio::test]
async fn compaction_pressure_trigger_fires_and_appends_focus_instructions() {
    // An unrecognized model id falls back to `UNKNOWN_MODEL_CONTEXT_FLOOR`
    // (200,000 tokens, see `provider::model_context_limit`'s doc comment) —
    // `reserve_tokens` just under that floor means any nontrivial history
    // trips the pressure trigger (`used + reserve > limit`).
    let config = Config::builder()
        .model("totally-unrecognized-model-xyz")
        .compaction_pressure(199_000, 500)
        .compaction_focus_instructions("stay focused on the login bug")
        .build();
    let mut agent = Agent::with_provider(config, Box::new(EchoLongProvider));
    for i in 0..8 {
        agent.send(format!("turn {i}")).await.unwrap();
    }
    let compacted = agent.history().iter().any(|m| {
        m.role == Role::System
            && m.content
                .as_deref()
                .is_some_and(|c| c.contains("earlier conversation compacted"))
    });
    assert!(compacted, "pressure trigger must have fired across 8 turns");
    let has_focus = agent.history().iter().any(|m| {
        m.content
            .as_deref()
            .is_some_and(|c| c.contains("Focus: stay focused on the login bug"))
    });
    assert!(
        has_focus,
        "the marker must carry the configured focus instructions"
    );
}

#[tokio::test]
async fn compaction_pressure_trigger_off_by_default_never_fires() {
    // No `compaction_reserve_tokens` set (the default): history grows
    // unbounded across many turns, byte-identical to pre-P4b behavior.
    let config = Config::builder()
        .model("totally-unrecognized-model-xyz")
        .build();
    let mut agent = Agent::with_provider(config, Box::new(EchoLongProvider));
    for i in 0..8 {
        agent.send(format!("turn {i}")).await.unwrap();
    }
    let compacted = agent.history().iter().any(|m| {
        m.content
            .as_deref()
            .is_some_and(|c| c.contains("compacted"))
    });
    assert!(
        !compacted,
        "pressure trigger must stay off when unconfigured"
    );
}

// ============================ usage records =================================

struct UsageProvider {
    calls: AtomicUsize,
}

#[async_trait]
impl Provider for UsageProvider {
    async fn complete(
        &self,
        _req: &ChatRequest,
        _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
    ) -> supercode_harness::Result<(ChatMessage, Usage)> {
        let n = self.calls.fetch_add(1, Ordering::SeqCst) as u64;
        let usage = Usage {
            prompt_tokens: 100 + n,
            completion_tokens: 10 + n,
            total_tokens: 110 + 2 * n,
            prompt_tokens_details: None,
        };
        Ok((ChatMessage::assistant(format!("answer {n}")), usage))
    }
}

#[tokio::test]
async fn usage_records_accumulate_per_turn_and_round_trip_losslessly_through_the_store() {
    let config = Config::builder().model("test-model").build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(UsageProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.send("q1").await.unwrap();
    agent.send("q2").await.unwrap();

    let records = agent.usage_records().to_vec();
    assert_eq!(records.len(), 2);
    assert_eq!(records[0].turn, 0);
    assert_eq!(records[0].model, "test-model");
    assert_eq!(records[0].prompt_tokens, 100);
    assert_eq!(records[1].turn, 1);
    assert_eq!(records[1].prompt_tokens, 101);

    let dir = temp_dir("usage-log-roundtrip");
    let store = SessionStore::open(&dir).unwrap();
    agent.save_usage_log(&store, "sess1").unwrap();
    let loaded = store.load_usage_log("sess1").unwrap();
    assert_eq!(
        loaded, records,
        "usage log must round-trip losslessly through the store"
    );

    let _ = std::fs::remove_dir_all(&dir);
}

#[tokio::test]
async fn usage_log_is_empty_by_default_no_calls_made_yet() {
    let config = Config::builder().build();
    let agent = Agent::with_provider(
        config,
        Box::new(UsageProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    assert!(agent.usage_records().is_empty());
}

// ============================== auto-title ==================================

struct FakeTitler {
    response: String,
}
impl SessionTitler for FakeTitler {
    fn title(&self, _preview: &str) -> supercode_harness::Result<String> {
        Ok(self.response.clone())
    }
    fn model_id(&self) -> &str {
        "fake-small-model"
    }
}

#[tokio::test]
async fn agent_auto_title_uses_installed_titler_and_persists_via_session_store() {
    let config = Config::builder().auto_title(true).build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(AlwaysFinalProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.send("please fix the login bug").await.unwrap();
    agent.set_session_titler(FakeTitler {
        response: "Fix the login bug".to_string(),
    });
    let title = agent.auto_title().unwrap();
    assert_eq!(title, "Fix the login bug");

    let dir = temp_dir("auto-title-roundtrip");
    let store = SessionStore::open(&dir).unwrap();
    store.save("sess1", &title, "{}").unwrap();
    let info = store
        .list()
        .into_iter()
        .find(|i| i.name == "sess1")
        .unwrap();
    assert_eq!(info.title, title, "title must round-trip through the store");

    let _ = std::fs::remove_dir_all(&dir);
}

#[tokio::test]
async fn agent_auto_title_is_none_when_no_titler_installed() {
    let config = Config::builder().auto_title(true).build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(AlwaysFinalProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.send("hello").await.unwrap();
    assert!(agent.auto_title().is_none());
}