fix: apply static value attribute as textarea content on CSR

[sankalpsthakur]

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---

Fixes #18574

Problem

Static value on <textarea> was inconsistent between CSR and SSR:

Case	CSR	SSR
<textarea value="hi">	empty	hi
<textarea value={'hi'}>	hi	hi

Browsers ignore the value HTML attribute on <textarea> (only child text content or the JS value property matter). The client compiler was baking static values into the template as value="hi", which is a no-op.

Fix

When compiling a static text value attribute on <textarea>, emit the value as template child text (with the same leading-newline and HTML-escape handling as the SSR path) instead of as an attribute. Dynamic value={...} already uses $.set_value and is unchanged.

Compiled client output goes from:

var root = $.from_html(`<textarea value="hi"></textarea>`);

to:

var root = $.from_html(`<textarea>hi</textarea>`);

defaultValue SSR remains out of scope here (tracked separately, e.g. #18446 / related PRs).

Tests

• runtime-runes/samples/textarea-static-value — static attr, static expression, dynamic, children, leading newline, escaped content; asserts value and defaultValue
• server-side-rendering/samples/textarea-static-value — expected HTML for static/dynamic/escaped cases

Local: FILTER=/textarea/ pnpm test and FILTER=textarea-static-value pnpm test pass.

---

AI disclosure: This contribution was prepared with assistance from an LLM-based coding agent. The change was reviewed and verified locally (repro, targeted tests) before opening the PR.

[pkg-svelte-dev]

Install the latest version of svelte from 4439916:

pnpm add https://pkg.svelte.dev/svelte/c/44399162f42761a8b0805751e66820a229dba6fb

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/svelte/pr/18627

Note

This PR is from a fork. A maintainer must approve approve each commit before it can be built and installed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 4439916

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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svelte	Patch

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