Stack for rivet-dev/rivet

• feat(rivetkit): update rivetkit rust crate #5202 qzolvpun · 2026-06-08 23:41:32 👈
• feat(depot): support disabling sqlite compaction via config #5205 ltzsplvu · 2026-06-08 23:41:37
• docs: restructure actor state & storage docs into single high-level page #5204 soovppnu · 2026-06-08 23:41:36
• fix(depot): fix migrating v1 -> v2 databases #5183 sxwzqqts · 2026-06-05 23:09:16
• refactor(depot): remove sqlite cold storage #5180 oxsukmwr · 2026-06-05 23:09:13
• main

Get stack: forklift get 5202
Push local edits: forklift submit
Merge when ready: forklift merge 5202

🚅 Deployed to the rivet-pr-5202 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
mcp-hub	✅ Success (View Logs)	Web	Jun 9, 2026 at 8:25 pm
website	❌ Build Failed (View Logs)	Web	Jun 9, 2026 at 8:25 pm
kitchen-sink	❌ Build Failed (View Logs)	Web	Jun 9, 2026 at 8:24 pm
frontend-cloud	❌ Build Failed (View Logs)	Web	Jun 8, 2026 at 11:42 pm
ladle	❌ Build Failed (View Logs)	Web	Jun 8, 2026 at 11:41 pm
frontend-inspector	❌ Build Failed (View Logs)	Web	Jun 8, 2026 at 11:41 pm

PR Review: Rust RivetKit Expansion

This is a well-structured expansion of Rust support that maintains good API design principles. Overall the code quality is solid and the additions are cohesive, but a few items warrant attention.

Findings

Potential Runtime Panics from Workflow Events

File: rivetkit-rust/packages/rivetkit/src/event.rs

Workflow event variants now map to unreachable!():

InspectorEvent::WfHistory(_) | InspectorEvent::WfReplay(_) => {
    unreachable!("Rust actors never host workflows")
}

If the engine ever sends these events to a Rust actor (e.g., due to a routing bug or version mismatch), this panics the actor process rather than gracefully degrading. Consider tracing::warn! + skip instead, following the fail-by-default rule only where panics are truly impossible by protocol invariant.

Missing #[serde(skip_serializing_if)] on New Request Fields

File: rivetkit-rust/packages/client/src/remote_manager.rs

The new runner_name_selector and crash_policy fields added to ActorsGetOrCreateRequest / ActorsCreateRequest are serialized unconditionally. Older engine versions that don't recognize these fields may reject the request or behave unexpectedly. Add #[serde(skip_serializing_if = "Option::is_none")] where optional, or confirm the engine always handles unknown fields gracefully.

Silent Error Discard on Response Body Read

File: rivetkit-rust/packages/client/src/remote_manager.rs (improved error message lines)

.unwrap_or_default()

Using .unwrap_or_default() when reading the response body for error messages silently hides body-read failures. Use .unwrap_or_else(|e| format!("<failed to read body: {e}>")) so errors are surfaced in the message.

Test Engine Reuse May Produce Flaky Tests

File: rivetkit-rust/packages/rivetkit/src/test.rs

The shared ENGINE_LOCK + engine reuse pattern is pragmatic but can cause issues if one test leaves the engine in a degraded state — subsequent tests may fail for unrelated reasons. Consider:

1. Adding a health-check ping before reuse rather than just checking if the JoinHandle is still alive.
2. Logging the port/PID on engine spawn to aid debugging CI failures.

CBOR Empty Array Deserialization — Comment Could Link to Protocol

File: rivetkit-rust/packages/rivetkit/src/event.rs (action deserialization)

The fix accepting 0x80 (empty CBOR array) as a valid unit variant is correct per the client protocol, but the comment could reference where the client encodes it this way to make the invariant verifiable. A // clients encode zero-arg calls as [] per envoy-client protocol with a file reference would help future readers.

Positive Notes

• The Queue<A> typed wrapper is clean and well-abstracted over the raw core queue API.
• Signal handling in registry.rs is correctly gated on cfg(unix) — no portability gaps.
• Unique pool names using nanosecond timestamps in test.rs correctly prevent cross-test routing interference.
• The hello-world-rust and chat-room-rust examples are comprehensive and include E2E tests.
• CLAUDE.md / AGENTS.md symlink added for rivetkit-rust — consistent with repo conventions.
• The unreachable!() arms on workflow event variants explicitly enumerate the variants rather than using _, consistent with CLAUDE.md's exhaustiveness rule.
• into_serverless_runtime() is a clean boundary for the serverless deployment model.