fix(guard, runner): enforce http body size and ws msg size by MasterPtato · Pull Request #4252 · rivet-dev/rivet

MasterPtato · 2026-02-21T01:40:52Z

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

My code follows the style guidelines of this project
I have performed a self-review of my code
I have commented my code, particularly in hard-to-understand areas
I have made corresponding changes to the documentation
My changes generate no new warnings
I have added tests that prove my fix is effective or that my feature works
New and existing unit tests pass locally with my changes

Fixes RVT-5967

railway-app · 2026-02-21T01:41:01Z

🚅 Deployed to the rivet-pr-4252 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
frontend-inspector	❌ Build Failed (View Logs)	Web	Feb 21, 2026 at 1:49 am
frontend-cloud	❌ Build Failed (View Logs)	Web	Feb 21, 2026 at 1:48 am
ladle	❌ Build Failed (View Logs)	Web	Feb 21, 2026 at 1:42 am
website	❌ Build Failed (View Logs)	Web	Feb 21, 2026 at 1:41 am
mcp-hub	✅ Success (View Logs)	Web	Feb 21, 2026 at 1:41 am

MasterPtato · 2026-02-21T01:41:03Z

How to use the Graphite Merge Queue

Add the label merge-queue to this PR to add it to the merge queue.

You must have a Graphite account in order to use the merge queue. Sign up using this link.

_{An organization admin has enabled the Graphite Merge Queue in this repository.} _{Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.}

This stack of pull requests is managed by Graphite. Learn more about stacking.

linear · 2026-02-21T01:41:43Z

RVT-5967 Add HTTP body size limits to pegboard gateway tunnel

claude · 2026-02-21T01:43:42Z

PR Review: fix(guard, runner): enforce http body size and ws msg size

Good direction — enforcing size limits at the guard layer is the right architectural approach. A few issues to address before merging.

Bug: Unused import (compile warning / dead code)

In engine/packages/pegboard-runner/src/ws_to_tunnel_task.rs line 9:

use rivet_guard_core::proxy_service::MAX_BODY_SIZE;

This import is never used. The size check at line 791 uses ctx.config().pegboard().runner_http_max_response_body_size() instead of MAX_BODY_SIZE. Either remove the import or use the constant for the check (which would also address the inconsistency noted below).

Required documentation update

CLAUDE.md requires: "When changing actor/runtime limits or behavior that affects documented limits (for example KV, queue, SQLite, WebSocket, HTTP, or timeouts), update website/src/content/docs/actors/limits.mdx in the same change."

limits.mdx currently states 128 MiB for both Max request/response body sizes. This PR enforces a 20 MiB guard-layer limit for non-streaming HTTP bodies. The docs are now incorrect and must be updated.

Orphaned error artifact

engine/artifacts/errors/guard.response_body_too_large.json still exists on disk. The corresponding ResponseBodyTooLarge struct was removed from pegboard-runner/src/errors.rs, but the artifact file was not deleted.

Status code semantics: 413 for all `invalid_request_body` errors

In guard-core/src/utils.rs:

("guard", "invalid_request_body") => StatusCode::PAYLOAD_TOO_LARGE,

Limited::new(body, MAX_BODY_SIZE).collect() can fail from IO errors (client disconnect mid-stream) in addition to body-too-large errors. Both cases return 413, which is misleading for IO failures. Consider inspecting for LengthLimitError to distinguish the cases, or renaming the error to request_body_too_large to signal intent (there is an existing guard.request_body_too_large.json artifact with exactly that name for the gateway's RequestBodyTooLarge error).

Inconsistent limits between layers

For non-streaming responses, the runner allows up to 128 MiB (runner_http_max_response_body_size default), but guard rejects at 20 MiB when buffering. An actor returning a 50 MiB non-streaming response would pass the runner check but be rejected by guard with BAD_GATEWAY. Streaming bypasses the buffer limit, so this is architecturally sound, but the gap is non-obvious and the unused MAX_BODY_SIZE import suggests the intent may have been to unify these.

Expanded tunnel message check scope (undocumented)

The old code only checked ToServerResponseStart body size. The new tunnel_message_inner_data_len_mk{1,2} functions check all message types including chunks and WebSocket messages. This broader scope is likely correct but was not described in the PR description.

tunnel.ts: size check after full body allocation

In engine/sdks/typescript/runner/src/tunnel.ts:

const body = response.body ? await response.arrayBuffer() : null;
if (body && body.byteLength > MAX_BODY_SIZE) {
    throw new Error("Response body too large");
}

response.arrayBuffer() fully reads the entire response into memory before the size check runs. A 50 MiB response still allocates 50 MiB before being rejected. For meaningful memory protection the check needs to happen while streaming (e.g., count bytes in a TransformStream and abort above the limit).

Minor

The typo fix in actor-driver.ts ("immeidatley" → "immediately") is a good catch.
Punctuation fix on UpstreamError message (added trailing period) is good for consistency.

graphite-app · 2026-02-21T01:58:11Z

engine/artifacts/errors/guard.invalid_response_body.json

+  "code": "invalid_response_body",
+  "group": "guard",
+  "message": "Unable to parse response body."
+}


Add a newline at the end of the file to fix the 'No newline at end of file' linting error

Spotted by Graphite Agent (based on CI logs)

Is this helpful? React 👍 or 👎 to let us know.

pkg-pr-new · 2026-02-27T00:21:59Z

More templates

@rivetkit/cloudflare-workers

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/cloudflare-workers@4252

@rivetkit/framework-base

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/framework-base@4252

@rivetkit/next-js

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/next-js@4252

@rivetkit/react

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/react@4252

rivetkit

pnpm add https://pkg.pr.new/rivet-dev/rivet/rivetkit@4252

@rivetkit/sql-loader

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/sql-loader@4252

@rivetkit/sqlite-vfs

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/sqlite-vfs@4252

@rivetkit/traces

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/traces@4252

@rivetkit/workflow-engine

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/workflow-engine@4252

@rivetkit/virtual-websocket

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/virtual-websocket@4252

@rivetkit/engine-runner

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/engine-runner@4252

@rivetkit/engine-runner-protocol

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/engine-runner-protocol@4252

commit: 350c871

MasterPtato requested a review from NathanFlurry February 21, 2026 01:40

MasterPtato mentioned this pull request Feb 21, 2026

fix(pegboard): add threshold parameters to runner protocol metadata #4247

Merged

11 tasks

railway-app bot temporarily deployed to rivet-frontend / rivet-pr-4252 February 21, 2026 01:41 Destroyed

MasterPtato mentioned this pull request Feb 21, 2026

fix(epoxy): make quorum sizes match paper #4234

Merged

11 tasks

MasterPtato mentioned this pull request Feb 21, 2026

chore: get docker compose working again #4246

Merged

11 tasks

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from 855bbaa to 889a15b Compare February 21, 2026 01:48

railway-app bot temporarily deployed to rivet-frontend / rivet-pr-4252 February 21, 2026 01:48 Destroyed

graphite-app bot reviewed Feb 21, 2026

View reviewed changes

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from 889a15b to e89cab8 Compare February 26, 2026 01:12

MasterPtato force-pushed the 02-19-fix_pegboard_add_threshold_parameters_to_runner_protocol_metadata branch from ce7323c to 30accfe Compare February 26, 2026 01:12

This was referenced Feb 26, 2026

chore: fix tests #4314

Merged

fix: various serverless bug fixes #4313

Merged

fix(ups): upgrade nats, fix chunking, add chunking tests #4315

Merged

chore: add log for runners with no alloc idx #4316

Merged

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from e89cab8 to a7065e4 Compare February 26, 2026 02:14

MasterPtato force-pushed the 02-19-fix_pegboard_add_threshold_parameters_to_runner_protocol_metadata branch 2 times, most recently from 0bb287d to 9c03cf4 Compare February 26, 2026 19:42

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from a7065e4 to 6df70f8 Compare February 26, 2026 19:42

This was referenced Feb 26, 2026

fix(rivetkit): stall stop handler until start completes #4192

Merged

fix: add serverless leak fix oneoff #4318

Merged

fix: remove useless config params #4319

Merged

fix: always trigger serverless ended early error #4320

Merged

MasterPtato added 4 commits February 26, 2026 16:03

fix(rivetkit): stall stop handler until start completes

2d6e590

fix(epoxy): make quorum sizes match paper

0027acd

chore: get docker compose working again

cc4d89e

fix(pegboard): add threshold parameters to runner protocol metadata

209ff35

fix(guard, runner): enforce http body size and ws msg size

350c871

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from 6df70f8 to 350c871 Compare February 27, 2026 00:12

MasterPtato force-pushed the 02-19-fix_pegboard_add_threshold_parameters_to_runner_protocol_metadata branch from 9c03cf4 to 209ff35 Compare February 27, 2026 00:12

NathanFlurry approved these changes Feb 27, 2026

View reviewed changes

Base automatically changed from 02-19-fix_pegboard_add_threshold_parameters_to_runner_protocol_metadata to main February 27, 2026 00:29

NathanFlurry merged commit caa07f9 into main Feb 27, 2026
16 of 35 checks passed

NathanFlurry deleted the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch February 27, 2026 00:30

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

fix(guard, runner): enforce http body size and ws msg size#4252

fix(guard, runner): enforce http body size and ws msg size#4252
NathanFlurry merged 5 commits intomainfrom
02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size

MasterPtato commented Feb 21, 2026 •

edited

Loading

Uh oh!

railway-app bot commented Feb 21, 2026 •

edited

Loading

Uh oh!

MasterPtato commented Feb 21, 2026 •

edited

Loading

Uh oh!

linear bot commented Feb 21, 2026

Uh oh!

claude bot commented Feb 21, 2026 •

edited

Loading

Uh oh!

graphite-app bot Feb 21, 2026

Uh oh!

pkg-pr-new bot commented Feb 27, 2026 •

edited

Loading

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

MasterPtato commented Feb 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Description

Type of change

How Has This Been Tested?

Checklist:

Uh oh!

railway-app bot commented Feb 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

MasterPtato commented Feb 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

How to use the Graphite Merge Queue

Uh oh!

linear bot commented Feb 21, 2026

Uh oh!

claude bot commented Feb 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

PR Review: fix(guard, runner): enforce http body size and ws msg size

Bug: Unused import (compile warning / dead code)

Required documentation update

Orphaned error artifact

Status code semantics: 413 for all invalid_request_body errors

Inconsistent limits between layers

Expanded tunnel message check scope (undocumented)

tunnel.ts: size check after full body allocation

Minor

Uh oh!

graphite-app bot Feb 21, 2026

Choose a reason for hiding this comment

Uh oh!

pkg-pr-new bot commented Feb 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

MasterPtato commented Feb 21, 2026 •

edited

Loading

railway-app bot commented Feb 21, 2026 •

edited

Loading

MasterPtato commented Feb 21, 2026 •

edited

Loading

claude bot commented Feb 21, 2026 •

edited

Loading

Status code semantics: 413 for all `invalid_request_body` errors

pkg-pr-new bot commented Feb 27, 2026 •

edited

Loading