Svelte 5: Reading 'setContext'd prop in child causes children to be re-created

[dooshiifox]

Describe the bug

Making a prop visible in a context, then reading that state inside a child (e.g., setContext('', { get exampleProp() { return exampleProp; }) -> getContext('').exampleProp) causes the snippet to be recreated. See repro and how Mounted child gets called every time show changes.

Passing through a store as a prop instead of a $state fixes it which is why its an annoyance and not blocking an upgrade.

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAAA5VTwW7bMAz9FVbowQa85J7E6YZedtlpBXaYB9SVaUeYLAkSva4w_O8TJTtr19MOQUSK7-nxkZ5FrzQGcfg-C9OOKA7ik3OiEvTiOAi_UBPGONjJS86cgvTK0bkxDanRWU_wgIGg93aERuz2HO0yrhFcxT-NBOFin6GG20AtYdG3OmB5bMxp_5fRnJ4mImvAGqmV_FnPRQn1GYoVe8P_5ZIe_8opFUBO3qMh_QIz3y7MmFkyY1KXr4BbrBvx7Fvn0DciEeUKLqhnM2l9LZMXpbtY9Bm1tvDNet3dnFJ_Z34kHaI1o-1Ur7ATB_ITLtXVSS74TytnGJDurSH8TRWE6xmWzeDN2SM3l42dk_gKkt7oRZUaiJBotvPWhaJcq6U1wWrcaTsUjfhip0geO8yAregW-x4lFdn6OY3wH2TyXl5aM2AHymwMVdR34CCNieloef00gWt5VlFYHmhdAzsOd6_ajvQUjWtECYd0m3jC-_tq0zasyxUFr5mGPNLkTUofc255I2e_h4dL3B6tDPIW0QXjJmnnFcETynYKMU3QSokhYFiF75hvhd_bcYwpZQYuTIjAJ7JgLIHHDxHRoY-7DI-Me1wdY3ymu9ut-t58A_PHFbjNsyij9veL9mP5A_xqhhW-AwAA

Logs

No response

System Info

System:
    OS: Linux 6.5 Arch Linux
    CPU: (32) x64 13th Gen Intel(R) Core(TM) i9-13900HX
    Memory: 18.23 GB / 31.19 GB
    Container: Yes
    Shell: 5.2.15 - /bin/bash
  Binaries:
    Node: 20.9.0 - /usr/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 10.2.1 - /usr/bin/npm
    pnpm: 8.10.0 - /usr/bin/pnpm
    bun: 1.0.4 - /usr/bin/bun
  Browsers:
    Chromium: 118.0.5993.117
    [Note: Seems this thing doesn't pick up Firefox. Running FF Dev 120.0b4 from AUR]
  npmPackages:
    svelte: ^5.0.0-next.2 => 5.0.0-next.2

Severity

annoyance

[dooshiifox]

Appears to have been fixed, presumably by #9665