$state.is always returns false during ssr

[david-roeger]

Describe the bug

The $state.is rune will always return false if run on the server even when $state and object are the same.

e.g.

const obj = { "hi": 1 };
const a = $state(obj)

// this is true on the server but false on the client which seems correct
console.log(a === obj)

// this is false on the server but true on the client which seems wrong
console.log($state.is(a, obj))

I would expect $state.is to return true on the server if the $state and object are the same.

Reproduction

SvelteLab

See the logs in the server console:

a === obj: true
$state.is(a, obj): false
a === b: true
$state.is(a, b): false

In the browser

a === obj: false
$state.is(a, obj): true
a === b: true
$state.is(a, b): true

Logs

No response

System Info

System:
    OS: macOS 14.4.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 2.67 GB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.0.0 - ~/.nvm/versions/node/v22.0.0/bin/node
    npm: 10.5.1 - ~/.nvm/versions/node/v22.0.0/bin/npm
    pnpm: 9.1.1 - ~/.nvm/versions/node/v22.0.0/bin/pnpm
    bun: 1.1.9 - /opt/homebrew/bin/bun
    Watchman: 2024.04.22.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 125.0.6422.112
    Safari: 17.4.1
  npmPackages:
    svelte: 5.0.0-next.144 => 5.0.0-next.144

Severity

blocking an upgrade