feat(2.0): seroval json mode by lxsmnsyc · Pull Request #2042 · solidjs/solid-start

lxsmnsyc · 2026-01-04T00:55:26Z

Pretty straight forward. Adds an opt-in mode to use json mode (set by default) for seroval streaming, this is because the js stream is affected by CSP.

Also adds streaming support for client-to-server communication (except for url-encoded requests), assuming that the browser it comes from supports it.

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pkg-pr-new · 2026-01-04T00:56:11Z

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npm i https://pkg.pr.new/solidjs/solid-start/@solidjs/start@2042

npm i https://pkg.pr.new/solidjs/solid-start/@solidjs/vite-plugin-nitro-2@2042

commit: 0e31479

packages/start/src/config/index.ts

packages/start/src/server/serialization.ts

packages/start/src/server/server-runtime.ts

packages/start/src/server/server-functions-handler.ts

packages/start/src/server/server-runtime.ts

katywings · 2026-01-15T23:14:20Z

Testing this branch on my project and uploading files through formData via https://github.com/hattipjs/hattip/tree/main/packages/base/multipart results in the following error 🙈:
[unhandledRejection] Error: Invalid content type

The error is throwed at this line: https://github.com/hattipjs/hattip/blob/15aa5ae4dec4478aa07785c85b2c85d4a753d0af/packages/base/multipart/src/form-data.ts#L79

It looks like with the changes in this branch, the upload doesn't set proper multipart boundaries anymore 🤔. The condition leading to the throw is !match.directives.boundary (https://github.com/hattipjs/hattip/blob/15aa5ae4dec4478aa07785c85b2c85d4a753d0af/packages/base/multipart/src/form-data.ts#L77C3-L77C29) - meaning: the content-type header misses the boundary flag 😅. E.g. the header should look as something like:

Content-Type: multipart/form-data; 
          boundary=gc0p4Jq0M2Yt08jU534c0p

(Reference: https://www.w3.org/Protocols/rfc1341/7_2_Multipart.html)

lxsmnsyc · 2026-01-16T02:26:38Z

Seemed like explicit definition of multipart/form-data overrides the derived content-type fetch does under the hood. Anyways fixed

brenelz · 2026-02-08T00:12:32Z

Whats the latest on this pr?

lxsmnsyc · 2026-02-09T08:50:17Z

@brenelz nothing much, but I haven't tested since the last commit lol

Copilot

Pull request overview

This PR introduces a new Seroval serialization layer for server functions with an opt-in response mode (js vs json, defaulting to json) to improve CSP compatibility, and expands the server-function transport to support more body types.

Changes:

Bumped seroval / seroval-plugins to ^1.5.0.
Added a new serialization module plus shared body-format helpers to support JS-stream vs JSON-stream response deserialization and additional body types (FormData, File, Blob, ArrayBuffer, Uint8Array, etc.).
Added new e2e/demo routes and tests for server-function round trips.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
pnpm-lock.yaml	Updates lockfile for `seroval`/`seroval-plugins` upgrade.
packages/start/package.json	Bumps `seroval` and `seroval-plugins` dependency ranges.
packages/start/src/config/index.ts	Adds `serialization.mode` option and injects `SEROVAL_MODE` define.
packages/start/src/server/serialization.ts	Introduces streaming serializer/deserializer utilities for JS and JSON modes.
packages/start/src/server/server-functions-shared.ts	Adds body-format header constants + helpers for encoding/decoding request/response bodies.
packages/start/src/server/server-runtime.ts	Updates client runtime to use the new serialization/body extraction helpers.
packages/start/src/server/server-functions-handler.ts	Updates server handler to use the new serialization + body extraction helpers.
apps/tests/src/routes/server-function-ping.tsx	Adds a basic server-function route for testing.
apps/tests/src/routes/server-function-form-data.tsx	Adds a FormData/File server-function route for testing.
apps/tests/src/routes/server-function-blob.tsx	Adds a Blob server-function route for testing.
apps/tests/src/e2e/server-function.test.ts	Adds new e2e tests for ping and FormData server functions.
.changeset/plenty-geese-enter.md	Adds changeset entry for the feature.

Files not reviewed (1)

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packages/start/src/server/server-functions-handler.ts

apps/tests/src/routes/server-function-blob.tsx

apps/tests/src/e2e/server-function.test.ts

packages/start/src/server/server-runtime.ts

packages/start/src/config/index.ts

apps/tests/src/routes/server-function-form-data.tsx

packages/start/src/server/server-functions-shared.ts

packages/start/src/server/serialization.ts

lxsmnsyc commented Jan 4, 2026

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lxsmnsyc mentioned this pull request Jan 4, 2026

feat(1.0): seroval json #2043

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lxsmnsyc commented Jan 4, 2026

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lxsmnsyc changed the title ~~feat: seroval json mode~~ feat(2.0): seroval json mode Jan 14, 2026

lxsmnsyc force-pushed the feat-seroval-json branch from 7932c2f to 25b3f44 Compare January 15, 2026 03:13

lxsmnsyc commented Jan 15, 2026

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lxsmnsyc force-pushed the feat-seroval-json branch from 820baec to db436df Compare February 9, 2026 11:29

atilafassina requested review from Copilot and katywings February 19, 2026 19:45

atilafassina approved these changes Feb 19, 2026

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lxsmnsyc added 11 commits February 19, 2026 20:45

add seroval json mode

3eca797

Update server-runtime.ts

b22bb73

Create plenty-geese-enter.md

1d5c88a

Fix client-server comms

91c17a4

Add tests

d90c103

Add new header

935ffa0

Update server-functions-handler.ts

31c15ab

Clone requests/responses

ff263f7

Add more formats

e11dfb3

Fix File encoding

932dcd2

Update server-functions-handler.ts

8cb05af

lxsmnsyc added 9 commits February 19, 2026 20:45

Update server-runtime.ts

bfaf652

Fix FormData missing boundary

df68b5b

Add form-data test

e3ce6db

fix tests

99966a2

Bump seroval to 1.5.0

265cf07

Bump seroval-plugins

7ad4f09

Add bidirectional encoding

c4c02ba

Fix error

a56ba83

Update server-functions-shared.ts

0defa47

atilafassina force-pushed the feat-seroval-json branch from db436df to 0defa47 Compare February 19, 2026 19:45

Copilot started reviewing on behalf of atilafassina February 19, 2026 19:45 View session

Copilot AI reviewed Feb 19, 2026

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fix copilot suggestions

fce37a8

katywings reviewed Feb 21, 2026

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packages/start/src/server/serialization.ts Show resolved Hide resolved

lxsmnsyc and others added 2 commits February 25, 2026 02:20

fix(seroval): add response guards

97a1793

add jsdoc to serialization mode (#2088)

0e31479

katywings approved these changes Feb 25, 2026

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atilafassina enabled auto-merge (squash) February 25, 2026 16:47

atilafassina disabled auto-merge February 25, 2026 16:48

atilafassina merged commit f6f0452 into main Feb 25, 2026
10 checks passed

atilafassina deleted the feat-seroval-json branch February 25, 2026 16:48

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