weavegraph 0.7.0

Graph-driven, concurrent agent workflow framework with versioned state, deterministic barrier merges, and rich diagnostics.
Documentation
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#![cfg(feature = "postgres")]

use rustc_hash::FxHashMap as FastMap;
use serde_json::{Value, json};
use std::sync::Arc;
use tokio::sync::Barrier;
use weavegraph::{
    channels::{
        Channel,
        errors::{ErrorEvent, ErrorScope, WeaveError},
    },
    message::Role,
    runtimes::{Checkpoint, Checkpointer, PostgresCheckpointer, checkpointer_postgres::StepQuery},
    state::VersionedState,
    types::NodeKind as Kind,
};

#[path = "common/mod.rs"]
mod support;
use support::state_with_user;

fn postgres_test_url() -> String {
    match std::env::var("WEAVEGRAPH_POSTGRES_TEST_URL") {
        Ok(url) => url,
        Err(_) => "postgresql://weavegraph:weavegraph@localhost:5432/weavegraph_test".to_owned(),
    }
}

async fn postgres_checkpointer() -> PostgresCheckpointer {
    let url = postgres_test_url();
    let connection = PostgresCheckpointer::connect(&url).await;
    match connection {
        Ok(store) => store,
        Err(error) => panic!("failed to connect to postgres at {url}: {error}"),
    }
}

fn session_id(name: &str) -> String {
    format!("wg-pg-{name}-{}", uuid::Uuid::new_v4())
}

fn state_with_entries(
    prompt: &str,
    entries: impl IntoIterator<Item = (&'static str, Value)>,
) -> VersionedState {
    entries
        .into_iter()
        .fold(state_with_user(prompt), |mut draft, (field, value)| {
            draft.extra.get_mut().insert(field.to_owned(), value);
            draft
        })
}

fn checkpoint_record(session: &str, step_number: u64, state: VersionedState) -> Checkpoint {
    Checkpoint {
        session_id: session.to_owned(),
        step: step_number,
        state,
        frontier: Vec::from([Kind::End]),
        versions_seen: FastMap::default(),
        concurrency_limit: 2,
        created_at: chrono::Utc::now(),
        ran_nodes: vec![],
        skipped_nodes: vec![],
        updated_channels: vec![],
    }
}

async fn latest_checkpoint(store: &PostgresCheckpointer, session: &str) -> Checkpoint {
    let Ok(found) = store.load_latest(session).await else {
        panic!("load_latest failed for {session}");
    };
    let Some(current) = found else {
        panic!("expected persisted checkpoint for {session}");
    };
    current
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn checkpoint_state_and_metadata_survive_postgres_roundtrip() {
    let store = postgres_checkpointer().await;
    let session = session_id("checkpoint-state-roundtrip");

    let mut persisted = checkpoint_record(
        &session,
        7,
        state_with_entries(
            "hello from postgres roundtrip",
            [("counter", json!(7)), ("status", json!("persisted"))],
        ),
    );
    persisted.frontier = vec![Kind::Custom("resume-node".to_owned()), Kind::End];
    persisted.concurrency_limit = 4;
    persisted.ran_nodes = vec![Kind::Start];
    persisted.skipped_nodes = vec![Kind::Custom("Skipped".to_owned())];
    persisted.updated_channels = vec!["messages".to_owned(), "extra".to_owned()];

    let mut seen_channels = FastMap::default();
    seen_channels.insert("messages".to_owned(), 3);
    seen_channels.insert("extra".to_owned(), 2);
    persisted
        .versions_seen
        .insert("ResumeNode".to_owned(), seen_channels);

    store.save(persisted).await.expect("save checkpoint");

    let loaded = latest_checkpoint(&store, &session).await;
    let persisted_message_version = loaded
        .versions_seen
        .get("ResumeNode")
        .and_then(|table| table.get("messages"))
        .copied();

    assert_eq!(loaded.step, 7);
    assert_eq!(loaded.concurrency_limit, 4);
    assert_eq!(
        loaded.frontier,
        vec![Kind::Custom("resume-node".to_owned()), Kind::End]
    );
    assert_eq!(persisted_message_version, Some(3));

    let messages = loaded.state.messages.snapshot();
    assert_eq!(messages.len(), 1);
    assert_eq!(messages[0].role, Role::User);
    assert_eq!(messages[0].content, "hello from postgres roundtrip");

    let extra = loaded.state.extra.snapshot();
    assert_eq!(extra.get("counter"), Some(&json!(7)));
    assert_eq!(extra.get("status"), Some(&json!("persisted")));
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn saved_sessions_appear_in_list_and_missing_session_returns_none() {
    let store = postgres_checkpointer().await;
    let created_sessions = [
        session_id("listed-a"),
        session_id("listed-b"),
        session_id("listed-c"),
    ];

    for name in &created_sessions {
        let snapshot = checkpoint_record(name, 1, state_with_user("session listing"));
        store.save(snapshot).await.expect("save checkpoint");
    }

    let sessions = store.list_sessions().await.expect("list sessions");
    for wanted in created_sessions {
        assert!(
            sessions.iter().any(|listed| listed == &wanted),
            "missing {wanted}"
        );
    }

    let absent = session_id("missing-session");
    let missing = store
        .load_latest(&absent)
        .await
        .expect("load missing session");
    assert!(missing.is_none());
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn step_query_paginates_results_newest_first() {
    let store = postgres_checkpointer().await;
    let session = session_id("step-query-pagination");

    for recorded_step in 1_u64..=5 {
        let mut snapshot = checkpoint_record(
            &session,
            recorded_step,
            state_with_entries(
                &format!("state recorded at step {recorded_step}"),
                [
                    ("step", json!(recorded_step)),
                    ("bucket", json!(recorded_step % 2)),
                ],
            ),
        );
        snapshot.ran_nodes = if recorded_step % 2 == 0 {
            vec![Kind::Start]
        } else {
            vec![Kind::Custom("worker".to_owned())]
        };
        snapshot.skipped_nodes = vec![Kind::End];
        snapshot.updated_channels = vec!["messages".to_owned()];
        store.save(snapshot).await.expect("save checkpoint");
    }

    let newest_query = StepQuery {
        offset: Some(0),
        limit: Some(2),
        ..StepQuery::default()
    };
    let newest_page = store
        .query_steps(&session, newest_query)
        .await
        .expect("query newest page");

    assert_eq!(newest_page.page_info.total_count, 5);
    assert_eq!(newest_page.page_info.page_size, 2);
    assert_eq!(newest_page.page_info.offset, 0);
    assert!(newest_page.page_info.has_next_page);
    assert_eq!(
        newest_page
            .checkpoints
            .iter()
            .map(|item| item.step)
            .collect::<Vec<_>>(),
        vec![5, 4]
    );

    let next_query = StepQuery {
        offset: Some(2),
        limit: Some(2),
        ..StepQuery::default()
    };
    let next_page = store
        .query_steps(&session, next_query)
        .await
        .expect("query next page");

    assert_eq!(
        next_page
            .checkpoints
            .iter()
            .map(|item| item.step)
            .collect::<Vec<_>>(),
        vec![3, 2]
    );
    assert_eq!(next_page.page_info.total_count, 5);
    assert!(next_page.page_info.has_next_page);
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn error_events_survive_postgres_roundtrip() {
    let store = postgres_checkpointer().await;
    let session = session_id("error-events-roundtrip");

    let mut state = state_with_user("error persistence");
    state.errors.get_mut().push(
        ErrorEvent::runner(
            session.clone(),
            3,
            WeaveError::msg("boom").with_details(json!({"code": "E_BANG"})),
        )
        .with_tags(vec!["postgres".to_owned(), "roundtrip".to_owned()])
        .with_context(json!({"retryable": false})),
    );

    let mut persisted = checkpoint_record(&session, 3, state);
    persisted.updated_channels = vec!["errors".to_owned()];
    store.save(persisted).await.expect("save checkpoint");

    let loaded = latest_checkpoint(&store, &session).await;
    let errors = loaded.state.errors.snapshot();
    let [event] = &errors[..] else {
        panic!("expected one error event");
    };
    assert_eq!(event.error.message, "boom");
    assert_eq!(event.error.details, json!({"code": "E_BANG"}));
    assert_eq!(event.tags, vec!["postgres", "roundtrip"]);
    assert_eq!(event.context, json!({"retryable": false}));
    assert!(matches!(event.scope, ErrorScope::Runner { step: 3, .. }));
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn duplicate_save_is_idempotent() {
    let store = postgres_checkpointer().await;
    let session = session_id("duplicate-save");

    let snapshot = checkpoint_record(
        &session,
        1,
        state_with_entries("same checkpoint twice", [("dedupe", json!(true))]),
    );

    store.save(snapshot.clone()).await.expect("first save");
    store.save(snapshot).await.expect("second save");

    let history = store
        .query_steps(
            &session,
            StepQuery {
                limit: Some(10),
                ..StepQuery::default()
            },
        )
        .await
        .expect("query deduplicated history");
    let latest = latest_checkpoint(&store, &session).await;

    assert_eq!(history.page_info.total_count, 1);
    assert_eq!(history.checkpoints.len(), 1);
    assert_eq!(history.checkpoints[0].step, latest.step);
    assert_eq!(
        latest.state.extra.snapshot().get("dedupe"),
        Some(&json!(true))
    );
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn save_with_stale_expected_step_is_rejected() {
    let store = postgres_checkpointer().await;
    let session = session_id("stale-expected-step");

    let first = checkpoint_record(&session, 1, state_with_user("first write"));
    store.save(first).await.expect("save first checkpoint");

    let second = checkpoint_record(&session, 2, state_with_user("second write"));
    store
        .save_with_concurrency_check(second, Some(1))
        .await
        .expect("save second checkpoint with matching expected step");

    let stale = checkpoint_record(&session, 3, state_with_user("stale write"));
    let failure = store
        .save_with_concurrency_check(stale, Some(1))
        .await
        .expect_err("stale expected step should fail");

    assert!(failure.to_string().contains("concurrency conflict"));

    let latest = latest_checkpoint(&store, &session).await;
    let history = store
        .query_steps(
            &session,
            StepQuery {
                limit: Some(10),
                ..StepQuery::default()
            },
        )
        .await
        .expect("query history after rejected write");

    assert_eq!(latest.step, 2);
    assert_eq!(latest.state.messages.snapshot()[0].content, "second write");
    assert_eq!(history.page_info.total_count, 2);
    assert_eq!(
        history
            .checkpoints
            .iter()
            .map(|item| item.step)
            .collect::<Vec<_>>(),
        vec![2, 1]
    );
}

#[tokio::test(worker_threads = 2, flavor = "multi_thread")]
async fn out_of_order_write_does_not_overwrite_higher_step() {
    let store = postgres_checkpointer().await;
    let session = session_id("out-of-order-write");

    let highest = checkpoint_record(
        &session,
        9,
        state_with_entries(
            "higher step wins",
            [("winner", json!("high-step")), ("step", json!(9))],
        ),
    );
    store.save(highest).await.expect("save higher step");

    let late_lower = checkpoint_record(
        &session,
        3,
        state_with_entries(
            "lower step arrives later",
            [("winner", json!("late-low-step")), ("step", json!(3))],
        ),
    );
    store.save(late_lower).await.expect("save lower step");

    let latest = latest_checkpoint(&store, &session).await;
    let history = store
        .query_steps(
            &session,
            StepQuery {
                limit: Some(10),
                ..StepQuery::default()
            },
        )
        .await
        .expect("query out-of-order history");

    assert_eq!(latest.step, 9);
    assert_eq!(
        latest.state.extra.snapshot().get("winner"),
        Some(&json!("high-step"))
    );
    assert_eq!(
        latest.state.messages.snapshot()[0].content,
        "higher step wins"
    );
    assert_eq!(history.page_info.total_count, 2);
    assert_eq!(
        history
            .checkpoints
            .iter()
            .map(|item| item.step)
            .collect::<Vec<_>>(),
        vec![9, 3]
    );
}

#[tokio::test(worker_threads = 4, flavor = "multi_thread")]
async fn concurrent_writers_only_one_wins_concurrency_check() {
    let store = Arc::new(postgres_checkpointer().await);
    let session = session_id("concurrent-writers");

    let seed = checkpoint_record(&session, 1, state_with_user("seed step"));
    store.save(seed).await.expect("save seed checkpoint");

    let barrier = Arc::new(Barrier::new(3));

    let first_store = Arc::clone(&store);
    let first_barrier = Arc::clone(&barrier);
    let first_session = session.clone();
    let first_writer = tokio::spawn(async move {
        let candidate = checkpoint_record(
            &first_session,
            2,
            state_with_entries(
                "writer one",
                [("writer", json!("writer-one")), ("step", json!(2))],
            ),
        );
        first_barrier.wait().await;
        first_store
            .save_with_concurrency_check(candidate, Some(1))
            .await
    });

    let second_store = Arc::clone(&store);
    let second_barrier = Arc::clone(&barrier);
    let second_session = session.clone();
    let second_writer = tokio::spawn(async move {
        let candidate = checkpoint_record(
            &second_session,
            2,
            state_with_entries(
                "writer two",
                [("writer", json!("writer-two")), ("step", json!(2))],
            ),
        );
        second_barrier.wait().await;
        second_store
            .save_with_concurrency_check(candidate, Some(1))
            .await
    });

    barrier.wait().await;

    let first_outcome = first_writer.await.expect("join writer one");
    let second_outcome = second_writer.await.expect("join writer two");
    let successes = [first_outcome.is_ok(), second_outcome.is_ok()]
        .into_iter()
        .filter(|won| *won)
        .count();

    let latest = latest_checkpoint(&store, &session).await;
    let history = store
        .query_steps(
            &session,
            StepQuery {
                limit: Some(10),
                ..StepQuery::default()
            },
        )
        .await
        .expect("query concurrent writer history");
    let elected = latest.state.extra.snapshot().get("writer").cloned();

    assert_eq!(successes, 1);
    assert_eq!(latest.step, 2);
    assert!(elected == Some(json!("writer-one")) || elected == Some(json!("writer-two")));
    assert_eq!(history.page_info.total_count, 2);
}