supercode-harness 0.4.4

//! TR-9 (T24) acceptance tests: `reduce::handoff::build_handoff` — `/handoff`
//! as extreme projection. Covers dev/01 (small projected view), dev/02
//! (same-sidecar reversibility + unaffected full-fidelity export), dev/03
//! (deterministic always-keeps), dev/04 (a scripted Tier-2 demo: the
//! continuation actually runs, drilling into a dropped turn via TR-1), and
//! dev/05 (objective drafting off by default, falls back on failure).
//!
//! No real LLM/network call anywhere: `FailingSummarizer`/`FakeSummarizer`
//! below are small deterministic in-process fakes, exactly like TR-7's own
//! `tr7_summary_guarantor.rs`/`reduce_summaries.rs`.

use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, Mutex};

use async_trait::async_trait;
use supercode_harness::reduce::handoff::{build_handoff, ObjectiveSource};
use supercode_harness::reduce::summarize::SpanSummarizer;
use supercode_harness::reduce::{self, ReductionKind, ReductionLog, ReductionPolicy};
use supercode_harness::server::RpcEngine;
use supercode_harness::session::{Session, SessionFormat};
use supercode_harness::sidecar::SidecarWriter;
use supercode_harness::store::SessionStore;
use supercode_harness::{
    Agent, ChatMessage, ChatRequest, Config, FrontendRuntime, FunctionCall, Provider, Role,
    ToolCall, Usage,
};

/// Build a bare assistant tool-call message (mirrors `rehydrate.rs`'s own
/// `tool_call_msg` test helper — not part of the crate's public API).
fn tool_call_msg(id: &str, name: &str, args: serde_json::Value) -> ChatMessage {
    ChatMessage {
        role: Role::Assistant,
        content: None,
        content_parts: None,
        tool_calls: Some(vec![ToolCall {
            id: id.to_string(),
            kind: "function".to_string(),
            function: FunctionCall {
                name: name.to_string(),
                arguments: args.to_string(),
            },
        }]),
        tool_call_id: None,
        name: None,
        metadata: Default::default(),
    }
}

fn temp_dir(tag: &str) -> PathBuf {
    static N: AtomicUsize = AtomicUsize::new(0);
    let dir = std::env::temp_dir().join(format!(
        "supercode-tr9-reduce-handoff-{tag}-{}-{}",
        std::process::id(),
        N.fetch_add(1, Ordering::SeqCst)
    ));
    std::fs::create_dir_all(&dir).unwrap();
    dir
}

fn filler(len: usize) -> String {
    (0..len).map(|i| (b'a' + (i % 26) as u8) as char).collect()
}

struct PlainReplies {
    calls: AtomicUsize,
}

struct CapturingPlainReply {
    request: Arc<Mutex<Option<ChatRequest>>>,
}

#[async_trait]
impl Provider for CapturingPlainReply {
    async fn complete(
        &self,
        req: &ChatRequest,
        _on_delta: &(dyn for<'a> Fn(&'a str) + Send + Sync),
    ) -> supercode_harness::Result<(ChatMessage, Usage)> {
        *self.request.lock().unwrap() = Some(req.clone());
        Ok((
            ChatMessage::assistant(format!("reply 0: {}", filler(200))),
            Usage::default(),
        ))
    }
}
#[async_trait]
impl Provider for PlainReplies {
    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!("reply {n}: {}", filler(200))),
            Usage::default(),
        ))
    }
}

/// Build a real, on-disk, full-fidelity sidecar (via a live `Agent` + a
/// scripted `Provider`, recording every turn) and return the reloaded
/// `Session` it produced — the canonical `msgs` slice every test below hands
/// to `build_handoff`.
async fn build_fixture_sidecar(dir: &Path, n_turns: usize) -> (PathBuf, Session) {
    let sidecar_path = dir.join("fixture.sidecar.jsonl");
    let config = Config::builder()
        .cwd(dir.to_path_buf())
        .system_prompt("you are a careful coding agent")
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(PlainReplies {
            calls: AtomicUsize::new(0),
        }),
    );
    let empty_session = Session::from_claude_code_str("").unwrap();
    let writer = SidecarWriter::create(&sidecar_path, &empty_session).unwrap();
    agent.set_recorder(writer);
    agent.set_reduction_policy(ReductionPolicy::default());

    for i in 0..n_turns {
        agent
            .send(format!(
                "turn {i}: investigate src/mod_{i}.rs — {}",
                filler(300)
            ))
            .await
            .unwrap();
    }

    let sidecar =
        Session::from_sidecar_str(&std::fs::read_to_string(&sidecar_path).unwrap()).unwrap();
    (sidecar_path, sidecar)
}

// ---------------------------------------------------------------------------
// dev/01 — projected view is a small fraction of the original.
// ---------------------------------------------------------------------------

#[tokio::test]
async fn dev01_handoff_view_is_at_most_10_percent_of_original_tokens() {
    let dir = temp_dir("dev01");
    let (_path, sidecar) = build_fixture_sidecar(&dir, 40).await;

    let result = build_handoff(
        &sidecar.messages,
        &["3".to_string()],
        4,
        Some("finish the migration"),
        false,
        None,
    )
    .unwrap();

    let full_tok = supercode_harness::tokens::estimate_view_tokens(&sidecar.messages);
    let view_tok = supercode_harness::tokens::estimate_view_tokens(&result.view);
    assert!(full_tok > 0);
    assert!(
        (view_tok as f64) <= 0.10 * (full_tok as f64),
        "view {view_tok} must be <=10% of full {full_tok}"
    );
    // Banner + objective + curated content only: no gap's original content
    // bytes appear directly in the view (only the deterministic stub does).
    let view_text = result
        .view
        .iter()
        .filter_map(|m| m.content.clone())
        .collect::<Vec<_>>()
        .join("\n");
    assert!(view_text.contains("=== HANDOFF ==="));
    assert!(view_text.contains("OBJECTIVE: finish the migration"));

    std::fs::remove_dir_all(&dir).ok();
}

// ---------------------------------------------------------------------------
// dev/02 — same-sidecar reversibility + unaffected full-fidelity export.
// ---------------------------------------------------------------------------

#[tokio::test]
async fn dev02_every_gap_expands_byte_exact_and_export_is_unaffected() {
    let dir = temp_dir("dev02");
    let (sidecar_path, sidecar) = build_fixture_sidecar(&dir, 30).await;
    let sidecar_str = std::fs::read_to_string(&sidecar_path).unwrap();

    let before_export = reduce::export_session(&sidecar_str, SessionFormat::Codex).unwrap();

    let result =
        build_handoff(&sidecar.messages, &["2".to_string()], 3, None, false, None).unwrap();
    assert!(!result.gap_ids.is_empty());

    // Full-fidelity export reads ONLY the sidecar — never `result.log`/
    // `result.view` — so it must be byte-identical before and after.
    let after_export = reduce::export_session(&sidecar_str, SessionFormat::Codex).unwrap();
    assert_eq!(before_export, after_export);
    assert_eq!(after_export.matches("sc-reduced").count(), 0);

    // Every dropped (gap) turn restores byte-exact via `invert`. `result.view`
    // carries one extra leading message beyond the canonical session — the
    // synthesized handoff banner (this fixture's sidecar never starts with a
    // real system-role message, so the banner is inserted fresh rather than
    // merged) — which carries no `sc.reduction` id and so passes through
    // `invert` untouched; every message after it must restore byte-exact.
    reduce::verify_log(&result.log, &sidecar).expect("verify_log must pass clean");
    let inverted = reduce::invert(&result.view, &result.log, &sidecar).unwrap();
    assert_eq!(inverted.len(), sidecar.messages.len() + 1);
    assert!(inverted[0]
        .content
        .as_deref()
        .unwrap()
        .contains("=== HANDOFF ==="));
    for (restored, original) in inverted[1..].iter().zip(&sidecar.messages) {
        assert_eq!(restored.content, original.content);
        assert_eq!(restored.role, original.role);
    }

    // `expand_reduction` (TR-1) restores each gap byte-exact directly too.
    for id in &result.gap_ids {
        let outcome =
            reduce::rehydrate::expand_reduction(&result.log, &sidecar.messages, None, id, None)
                .unwrap();
        assert!(!outcome.content.is_empty());
        assert!(
            !outcome.content.contains("HANDOFF"),
            "expanded content must be the genuine original, never banner text"
        );
    }

    std::fs::remove_dir_all(&dir).ok();
}

#[tokio::test]
async fn frontend_and_headless_reduced_continuations_are_disk_identical_and_invertible() {
    let dir = temp_dir("frontend-headless-parity");
    let (source_path, sidecar) = build_fixture_sidecar(&dir, 5).await;
    let source_before = std::fs::read(&source_path).unwrap();
    let handoff = build_handoff(&sidecar.messages, &[], 2, None, false, None).unwrap();
    assert!(!handoff.log.reductions.is_empty());

    let headless_store = SessionStore::open(dir.join("headless-store")).unwrap();
    let frontend_store = SessionStore::open(dir.join("frontend-store")).unwrap();
    let name = "continued";
    let headless_capture = Arc::new(Mutex::new(None));
    let frontend_capture = Arc::new(Mutex::new(None));
    let fixed_timestamp = "2026-07-19T12:00:00.000Z";
    let make_agent = |sidecar_path: &Path, request: Arc<Mutex<Option<ChatRequest>>>| {
        let mut agent = Agent::with_provider(
            Config::builder().cwd(dir.clone()).build(),
            Box::new(CapturingPlainReply { request }),
        );
        agent.load_session(sidecar.clone());
        agent.set_recorder(
            SidecarWriter::create_with_timestamp(sidecar_path, &sidecar, fixed_timestamp).unwrap(),
        );
        agent.set_reduction_policy(ReductionPolicy {
            clear_turns_older_than: None,
            ..ReductionPolicy::default()
        });
        agent.set_reduction_log(handoff.log.clone());
        agent
    };

    let mut headless = make_agent(&headless_store.sidecar_path(name), headless_capture.clone());
    let headless_reply = headless.send("same reduced continuation").await.unwrap();
    let headless_log = headless.reduction_log().clone();
    headless_store
        .save_reduction_log(name, &headless_log)
        .unwrap();

    let runtime = RpcEngine::new_named(
        make_agent(&frontend_store.sidecar_path(name), frontend_capture.clone()),
        "reduced-frontend",
        None,
    );
    let frontend_reply =
        FrontendRuntime::submit(runtime.as_ref(), "same reduced continuation".into())
            .await
            .unwrap();
    let frontend_log = runtime
        .finalize_with(|agent| agent.reduction_log().clone())
        .await;
    frontend_store
        .save_reduction_log(name, &frontend_log)
        .unwrap();

    assert_eq!(frontend_reply, headless_reply);
    let headless_request = headless_capture.lock().unwrap().take().unwrap();
    let frontend_request = frontend_capture.lock().unwrap().take().unwrap();
    assert_eq!(frontend_request, headless_request);
    let reduced_stubs = frontend_request
        .messages
        .iter()
        .filter_map(|message| message.content.as_deref())
        .filter_map(reduce::stub::parse)
        .collect::<Vec<_>>();
    assert!(!reduced_stubs.is_empty());
    for (_, id, _) in &reduced_stubs {
        assert!(frontend_log
            .reductions
            .iter()
            .any(|reduction| reduction.id == *id));
    }

    assert_eq!(
        std::fs::read(frontend_store.sidecar_path(name)).unwrap(),
        std::fs::read(headless_store.sidecar_path(name)).unwrap()
    );
    assert_eq!(
        std::fs::read(dir.join("frontend-store/continued.reduction.json")).unwrap(),
        std::fs::read(dir.join("headless-store/continued.reduction.json")).unwrap()
    );
    assert_eq!(std::fs::read(&source_path).unwrap(), source_before);

    let disk_sidecar = frontend_store.load_sidecar(name).unwrap().unwrap();
    let reloaded = Session::from_sidecar_str(&disk_sidecar).unwrap();
    let reloaded_log: ReductionLog = frontend_store.load_reduction_log(name).unwrap().unwrap();
    reduce::verify_log(&reloaded_log, &reloaded).unwrap();
    let policy = ReductionPolicy {
        clear_turns_older_than: None,
        ..ReductionPolicy::default()
    };
    let (reduced_view, reprojected_log) = reduce::project(&reloaded, &policy, &reloaded_log);
    assert_eq!(reprojected_log, reloaded_log);
    assert!(reduced_view.iter().any(|message| {
        message
            .content
            .as_deref()
            .is_some_and(|content| content.contains(reduce::REDUCTION_SENTINEL))
    }));
    assert_eq!(
        reduce::invert(&reduced_view, &reloaded_log, &reloaded).unwrap(),
        reloaded.messages
    );
    let headless_disk_sidecar = headless_store.load_sidecar(name).unwrap().unwrap();
    let headless_export =
        reduce::export_session(&headless_disk_sidecar, SessionFormat::ClaudeCode).unwrap();
    let frontend_export = reduce::export_session(&disk_sidecar, SessionFormat::ClaudeCode).unwrap();
    assert_eq!(frontend_export, headless_export);
    assert!(!frontend_export.contains(reduce::REDUCTION_SENTINEL));
    let export_reloaded = Session::from_claude_code_str(&frontend_export).unwrap();
    assert_eq!(
        export_reloaded
            .messages
            .iter()
            .map(|message| (message.role, message.content.as_deref()))
            .collect::<Vec<_>>(),
        reloaded
            .messages
            .iter()
            .map(|message| (message.role, message.content.as_deref()))
            .collect::<Vec<_>>()
    );
    std::fs::remove_dir_all(&dir).ok();
}

// ---------------------------------------------------------------------------
// dev/03 — deterministic always-keeps.
// ---------------------------------------------------------------------------

#[tokio::test]
async fn dev03_system_prompt_and_last_k_turns_are_always_kept() {
    let dir = temp_dir("dev03");
    let (_path, sidecar) = build_fixture_sidecar(&dir, 25).await;

    // No `--keep` tokens at all — only the deterministic always-keeps.
    let result = build_handoff(&sidecar.messages, &[], 5, None, false, None).unwrap();

    let len = sidecar.messages.len();
    for idx in (len - 5)..len {
        assert!(
            result.kept_indices.contains(&idx),
            "last-5 index {idx} must always be kept: {:?}",
            result.kept_indices
        );
    }
    // The kept tail's actual content must be present verbatim in the view
    // (not stubbed) — find the last user message's content and confirm it
    // rides through untouched.
    let last_user_content = sidecar
        .messages
        .iter()
        .rev()
        .find(|m| m.role == Role::User)
        .and_then(|m| m.content.clone())
        .unwrap();
    let view_text = result
        .view
        .iter()
        .filter_map(|m| m.content.clone())
        .collect::<Vec<_>>()
        .join("\n");
    assert!(view_text.contains(&last_user_content));

    std::fs::remove_dir_all(&dir).ok();
}

// ---------------------------------------------------------------------------
// dev/05 — objective drafting off by default; falls back on failure.
// ---------------------------------------------------------------------------

struct FailingSummarizer;
impl SpanSummarizer for FailingSummarizer {
    fn summarize(&self, _span_text: &str) -> supercode_harness::reduce::ReductionResult<String> {
        Err(supercode_harness::reduce::ReductionError::new(
            "injected failure",
        ))
    }
    fn model_id(&self) -> &str {
        "failing-model"
    }
}

struct WorkingSummarizer;
impl SpanSummarizer for WorkingSummarizer {
    fn summarize(&self, span_text: &str) -> supercode_harness::reduce::ReductionResult<String> {
        Ok(format!("drafted objective over {} chars", span_text.len()))
    }
    fn model_id(&self) -> &str {
        "drafting-model"
    }
}

#[tokio::test]
async fn dev05_draft_objective_off_by_default_falls_back_and_drafts_when_enabled() {
    let dir = temp_dir("dev05");
    let (_path, sidecar) = build_fixture_sidecar(&dir, 20).await;

    // `draft_objective` off (the default posture) — a summarizer being
    // injected must not matter at all: no objective, plain banner.
    let off = build_handoff(
        &sidecar.messages,
        &[],
        3,
        None,
        false,
        Some(&WorkingSummarizer),
    )
    .unwrap();
    assert_eq!(off.objective_source, ObjectiveSource::Fallback);
    assert_eq!(off.objective_text, None);
    assert!(!off.view[0]
        .content
        .as_deref()
        .unwrap()
        .contains("OBJECTIVE:"));

    // `draft_objective` on, but the injected summarizer always errors:
    // fault-injection contract (SPEC.md dev/03-style fallback) — falls back
    // identically, never propagates the error.
    let failing = build_handoff(
        &sidecar.messages,
        &[],
        3,
        None,
        true,
        Some(&FailingSummarizer),
    )
    .unwrap();
    assert_eq!(failing.objective_source, ObjectiveSource::Fallback);
    assert_eq!(failing.objective_text, None);

    // `draft_objective` on with a working summarizer and no user text: the
    // drafted paragraph is used.
    let drafted = build_handoff(
        &sidecar.messages,
        &[],
        3,
        None,
        true,
        Some(&WorkingSummarizer),
    )
    .unwrap();
    assert_eq!(drafted.objective_source, ObjectiveSource::Drafted);
    assert!(drafted
        .objective_text
        .as_deref()
        .unwrap()
        .contains("drafted objective over"));

    // User-supplied text always wins outright, even with drafting on and a
    // WORKING summarizer injected (no dependency on TR-7 at all).
    let user_wins = build_handoff(
        &sidecar.messages,
        &[],
        3,
        Some("do the actual thing"),
        true,
        Some(&WorkingSummarizer),
    )
    .unwrap();
    assert_eq!(user_wins.objective_source, ObjectiveSource::UserSupplied);
    assert_eq!(
        user_wins.objective_text.as_deref(),
        Some("do the actual thing")
    );

    std::fs::remove_dir_all(&dir).ok();
}

// ---------------------------------------------------------------------------
// dev/04 — Tier-2 demo: an agent loop resumed on the handoff projection
// runs, consults a curated stub, drills into a dropped turn via TR-1, and
// completes a task. Transcript archived (git-ignored `target/`), following
// `rehydrate.rs`'s TR-1 dev/06 / `reduce_summaries_demo.rs`'s TR-7 dev/06
// convention.
// ---------------------------------------------------------------------------

const SECRET: &str = "the rollback token is RB-4471-XQ";

/// The CONTINUATION agent's provider — the fixture (secret turn + filler)
/// was already recorded by a SEPARATE agent/provider in
/// `build_fixture_sidecar_with_secret`; this one only ever sees the ONE new
/// question turn asked below, so its own call index starts at 0 for that
/// turn: n=0 asks the question and must consult `sidecar_search` (the model
/// can't see the secret directly, it's handoff-cleared); n=1 must
/// `expand_reduction` (TR-1) on the match; n=2 answers using the recovered
/// content.
struct HandoffDemoProvider {
    calls: AtomicUsize,
}
#[async_trait]
impl Provider for HandoffDemoProvider {
    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 {
            let body = serde_json::to_string(&req.messages).unwrap();
            assert!(
                body.contains("=== HANDOFF ==="),
                "the handoff banner must be present in the request view: {body}"
            );
            assert!(
                !body.contains("RB-4471-XQ"),
                "the secret must not be directly visible after handoff"
            );
            assert!(req.tools.iter().any(|t| t.name == "sidecar_search"));
            return Ok((
                tool_call_msg(
                    "s1",
                    "sidecar_search",
                    serde_json::json!({"query": "rollback token"}),
                ),
                Usage::default(),
            ));
        }
        if n == 1 {
            let last = req.messages.last().unwrap();
            assert_eq!(last.role, Role::Tool);
            let result: reduce::rehydrate::SidecarSearchResult =
                serde_json::from_str(last.content.as_deref().unwrap()).unwrap();
            assert_eq!(result.matches.len(), 1, "{result:?}");
            return Ok((
                tool_call_msg(
                    "e1",
                    "expand_reduction",
                    serde_json::json!({"reduction_id": result.matches[0].reduction_id}),
                ),
                Usage::default(),
            ));
        }
        let last = req.messages.last().unwrap();
        assert_eq!(last.role, Role::Tool);
        let expanded = last.content.clone().unwrap_or_default();
        assert!(expanded.contains("RB-4471-XQ"), "{expanded}");
        Ok((
            ChatMessage::assistant("The rollback token is RB-4471-XQ."),
            Usage::default(),
        ))
    }
}

#[tokio::test]
async fn dev04_tier2_demo_continuation_drills_into_a_handoff_dropped_turn() {
    let dir = temp_dir("dev04-demo");
    let n_filler = 5;

    let (_path, sidecar) = build_fixture_sidecar_with_secret(&dir, n_filler).await;

    // Build the handoff offline over the recorded sidecar: keep only the
    // last 2 turns (the secret's turn — near the front — must land in a
    // gap).
    let result = build_handoff(&sidecar.messages, &[], 2, None, false, None).unwrap();
    assert!(
        result
            .log
            .reductions
            .iter()
            .any(|r| matches!(r.kind, ReductionKind::TurnsCleared { .. })),
        "the secret's turn must be handoff-cleared"
    );

    // Continue on a FRESH live agent whose `history` stays the FULL
    // canonical session (never shrunk) — only `reduction_log` changes,
    // exactly like a normal reduced-mode continuation. The banner rides the
    // agent's own system prompt (config-level, never part of the sidecar),
    // matching TR-9's "view-only, never in the sidecar" contract for a live
    // continuation.
    let banner = result.view[0].content.clone().unwrap();
    let config = Config::builder()
        .cwd(dir.to_path_buf())
        .system_prompt(banner)
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(HandoffDemoProvider {
            calls: AtomicUsize::new(0),
        }),
    );
    agent.load_session(sidecar.clone());
    agent.set_reduction_policy(ReductionPolicy {
        clear_turns_older_than: None,
        ..ReductionPolicy::default()
    });
    agent.set_reduction_log(result.log.clone());

    let reply = agent.send("What was the rollback token?").await.unwrap();
    assert_eq!(reply, "The rollback token is RB-4471-XQ.");

    let workspace_target = Path::new(env!("CARGO_MANIFEST_DIR")).join("../../target");
    std::fs::create_dir_all(&workspace_target).ok();
    let transcript_path = workspace_target.join("tr9-handoff-demo-transcript.jsonl");
    agent.save_transcript(&transcript_path).unwrap();
    assert!(transcript_path.exists());
    eprintln!(
        "TR-9 dev/04 demo transcript archived at {}",
        transcript_path.display()
    );

    std::fs::remove_dir_all(&dir).ok();
}

async fn build_fixture_sidecar_with_secret(dir: &Path, n_filler: usize) -> (PathBuf, Session) {
    let sidecar_path = dir.join("secret.sidecar.jsonl");
    let config = Config::builder()
        .cwd(dir.to_path_buf())
        .system_prompt("you are a careful coding agent")
        .build();
    let mut agent = Agent::with_provider(
        config,
        Box::new(PlainReplies {
            calls: AtomicUsize::new(0),
        }),
    );
    let empty_session = Session::from_claude_code_str("").unwrap();
    let writer = SidecarWriter::create(&sidecar_path, &empty_session).unwrap();
    agent.set_recorder(writer);
    agent.set_reduction_policy(ReductionPolicy::default());

    agent
        .send(format!("Please remember this: {SECRET}"))
        .await
        .unwrap();
    for i in 0..n_filler {
        agent
            .send(format!("filler turn {i}, just say ack"))
            .await
            .unwrap();
    }

    let sidecar =
        Session::from_sidecar_str(&std::fs::read_to_string(&sidecar_path).unwrap()).unwrap();
    (sidecar_path, sidecar)
}