fix: prevent script dedup inside <template> by seroperson · Pull Request #15980 · withastro/astro

seroperson · 2026-03-18T12:03:24Z

When a component with a script was first used inside a <template>, Astro's deduplication prevented the script from rendering outside the template, breaking non-template instances. This PR makes such scripts are not deduplicated. Should be merged after withastro/compiler#1156.

Changes

Adds templateEnter / templateExit functions to be inlined by compiler inside of <template> tags. These functions add instructions that track <template> nesting depth during rendering.
stringifyChunk skips dedup for scripts when templateDepth > 0. The script still renders inside the template but is also rendered outside for non-template instances.

Testing

Added astro-script-template-dedup integration test with four cases:

Component used inside <template> first, then outside: verifies script appears in both places
Component used outside first, then inside: verifies normal dedup still works
Two components outside, then inside: verifies normal dedup still works x2
Nested <template> elements: verifies depth tracking handles nesting

Docs

Docs aren't required as it's a bugfix.

changeset-bot · 2026-03-18T12:03:31Z

🦋 Changeset detected

Latest commit: 3dddc73

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

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codspeed-hq · 2026-03-18T12:20:44Z

Merging this PR will not alter performance

✅ 18 untouched benchmarks

_{Comparing seroperson:i15389-template-script-dedup (3dddc73) with main (5120ecd)¹}

No successful run was found on main (f99f32a) during the generation of this report, so 5120ecd was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

matthewp

This is a very expensive change, for something that is a bit of a corner case. I don't want to make this change this way. Will explain an alternative approach in a comment.

matthewp · 2026-03-19T14:50:38Z

Basically we need to know that we are "inside of a template" in order to maybe not emit the script. I think that's really only possible through a compiler change.

If you have that, you would know when you've exited all possible templates and then could emit the script. cc @Princesseuh

seroperson · 2026-03-19T18:34:05Z

@matthewp Thank you for the review! Oh, I wasn't aware about such ability at all. Yea, compiler-based approach looks much better.

I filled the PR to compiler and did necessary changes here to support it. Well, then waiting compiler to be merged and then I'll update the version here.

P.S. I actually "moved" this render instruction to be inlined by compiler, so logic within this PR left mostly unchanged (except placing instructions of course).

seroperson · 2026-03-29T20:03:36Z

I've also mirrored the same functionality in compiler-rs repo: withastro/compiler-rs#17

Closes withastro#15389

ematipico · 2026-04-21T14:41:38Z

@seroperson are the failures in CI expected?

seroperson · 2026-04-21T14:49:32Z

@ematipico we are waiting for the compiler to be released, then here we should bump its version and ensure everything works

…t-dedup # Conflicts: # packages/astro/package.json # pnpm-lock.yaml

github-actions

This PR is blocked because it contains a minor changeset. A reviewer will merge this at the next release if approved.

Princesseuh

Code good!

ArmandPhilippot

A nit for consistency with how we write changesets (ie. present tense verb), otherwise LGTM!

yanthomasdev

Docs LGTM after Armand suggestion is applied.

Co-authored-by: Armand Philippot <[email protected]>

Co-authored-by: Erika <[email protected]>

merge

This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [astro](https://astro.build) ([source](https://github.com/withastro/astro/tree/HEAD/packages/astro)) | [`6.1.10` → `6.2.1`](https://renovatebot.com/diffs/npm/astro/6.1.10/6.2.1) | ![age](https://developer.mend.io/api/mc/badges/age/npm/astro/6.2.1?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/astro/6.1.10/6.2.1?slim=true) | --- ### Release Notes <details> <summary>withastro/astro (astro)</summary> ### [`v6.2.1`](https://github.com/withastro/astro/blob/HEAD/packages/astro/CHANGELOG.md#621) [Compare Source](https://github.com/withastro/astro/compare/[email protected]@6.2.1) ##### Patch Changes - [#16531](withastro/astro#16531) [`76db01d`](withastro/astro@76db01d) Thanks [@rodrigosdev](https://github.com/rodrigosdev)! - Fixes config validation for omitted `integrations` fields with newer Zod versions. - [#16535](withastro/astro#16535) [`7df0fe4`](withastro/astro@7df0fe4) Thanks [@rururux](https://github.com/rururux)! - Fixed an issue where a warning was displayed when the `server` property was missing during config validation, even though it is not required. - [#16534](withastro/astro#16534) [`5cf6c51`](withastro/astro@5cf6c51) Thanks [@matthewp](https://github.com/matthewp)! - Fixes compatibility with Zod 4.4.0 for the `server` config property and error formatting ### [`v6.2.0`](https://github.com/withastro/astro/blob/HEAD/packages/astro/CHANGELOG.md#620) [Compare Source](https://github.com/withastro/astro/compare/[email protected]@6.2.0) ##### Minor Changes - [#16187](withastro/astro#16187) [`fe58071`](withastro/astro@fe58071) Thanks [@gllmt](https://github.com/gllmt)! - Adds a `waitUntil` option to the `RenderOptions` so that adapters can forward runtime background-task hooks to Astro. When provided by an adapter, runtime cache providers receive `context.waitUntil` in `CacheProvider.onRequest()`, which allows background cache work such as stale-while-revalidate without blocking the response. The Cloudflare adapter now forwards `ExecutionContext.waitUntil` to this API. - [#16290](withastro/astro#16290) [`a49637a`](withastro/astro@a49637a) Thanks [@ViVaLaDaniel](https://github.com/ViVaLaDaniel)! - Ensures that `server.allowedHosts` (and `vite.preview.allowedHosts`) configuration is respected when using `astro preview` with the `@astrojs/cloudflare` adapter. This improves security by preventing DNS rebinding attacks when previewing Cloudflare builds locally. - [#15725](withastro/astro#15725) [`4108ec1`](withastro/astro@4108ec1) Thanks [@meyer](https://github.com/meyer)! - Adds support for a new `'jsx'` value for the `compressHTML` option. When set, whitespace is stripped using JSX whitespace rules instead of the default HTML compression strategy. ```js // astro.config.mjs import { defineConfig } from 'astro/config'; export default defineConfig({ compressHTML: 'jsx', }); ``` In JSX, whitespaces never matter, as such, no amount of indentation, or newlines will not affect the rendered output. For instance, the following code: ```jsx <div> <span>foo</span> <span>bar</span> </div> ``` will be rendered as `foobar`, whereas with HTML whitespace rules, a space would be present between the words due to the newline and indentation between the tags. - [#16477](withastro/astro#16477) [`28fb3e1`](withastro/astro@28fb3e1) Thanks [@ematipico](https://github.com/ematipico)! - Adds experimental support for configurable log handlers. This experimental feature provides better control over Astro's logging infrastructure by allowing users to replace the default console output with custom logging implementations (e.g., structured JSON). This is particularly useful for users using on-demand rendering and wishing to connect their log aggregation services, such as Kibana, Logstash, CloudWatch, Grafana, or Loki. By default, Astro provides three built-in log handlers (`json`, `node`, and `console`), but you can also create your own. ##### JSON logging JSON logging can be enabled via the CLI for the `build`, `dev`, and `sync` commands using the `experimentalJson` flag: ```js // astro.config.mjs import { defineConfig, logHandlers } from 'astro/config'; export default defineConfig({ experimental: { logger: logHandlers.json({ pretty: true, level: 'warn', }), }, }); ``` ##### Custom logger You can also create your own custom logger by implementing the correct interface: ```js // astro.config.mjs import { defineConfig } from 'astro/config'; export default defineConfig({ experimental: { logger: { entrypoint: '@org/custom-logger', }, }, }); ``` ```ts // @org/custom-logger.js import type { AstroLoggerDestination, AstroLoggerMessage } from 'astro'; import { matchesLevel } from 'astor/logger'; function customLogger(level = 'info'): AstroLoggerDestination { return { write(message: AstroLoggerMessage) { if (matchesLevel(message.level, level)) { // write message somewhere } }, }; } export default customLogger; ``` For more information on enabling and using this feature in your project, see the [Experimental Logger docs](https://docs.astro.build/en/reference/experimental-flags/logger/). For a complete overview and to give feedback on this experimental API, see the [Custom logger RFC](https://github.com/withastro/roadmap/blob/logger/proposals/0059-custom-logger.md). - [#16333](withastro/astro#16333) [`0f7c3c8`](withastro/astro@0f7c3c8) Thanks [@florian-lefebvre](https://github.com/florian-lefebvre)! - Adds an experimental flag `svgOptimizer` that enables automatic optimization of your SVG components using the provided optimizer. This supersedes the `svgo` experimental flag, which is now removed. When enabled, your imported SVG files used as components will be optimized for smaller file sizes and better performance while maintaining visual quality. This can significantly reduce the size of your SVG assets by removing unnecessary metadata, comments, and redundant code. Astro ships with a [SVGO](https://svgo.dev/) based optimizer, but any can be used. To enable this feature, add the experimental flag in your Astro config and remove `svgo` if it was enabled: ```diff // astro.config.mjs -import { defineConfig } from "astro/config"; +import { defineConfig, svgoOptimizer } from "astro/config"; export default defineConfig({ + experimental: { + svgOptimizer: svgoOptimizer() - svgo: true + } }); ``` For more information on enabling and using this feature in your project, see the [experimental SVG optimization docs](https://docs.astro.build/en/reference/experimental-flags/svg-optimization/). - [#16302](withastro/astro#16302) [`f6f8e80`](withastro/astro@f6f8e80) Thanks [@florian-lefebvre](https://github.com/florian-lefebvre)! - Adds a new `experimental_getFontFileURL()` method to resolve font file URLs when using the Fonts API The `fontData` object exported from `astro:assets` was introduced to provide low-level access to font family data for advanced usage. One of the goals of this API was to be able to resolve buffers using URLs. However, it turned out to be impractical, especially during prerendering. Astro now exports a new `experimental_getFontFileURL()` helper function from `astro:assets` to resolve font file URLs from `fontData`. For example, when using [satori](https://github.com/vercel/satori) to generate Open Graph images: ```diff // src/pages/og.png.ts import type { APIRoute } from "astro"; -import { fontData } from "astro:assets"; +import { fontData, experimental_getFontFileURL } from "astro:assets"; -import { outDir } from "astro:config/server"; -import { readFile } from "node:fs/promises"; import satori from "satori"; import { html } from "satori-html"; import sharp from "sharp"; export const GET: APIRoute = async (context) => { const fontPath = fontData["--font-roboto"][0]?.src[0]?.url; if (fontPath === undefined) { throw new Error("Cannot find the font path."); } - const data = import.meta.env.DEV - ? await fetch(new URL(fontPath, context.url.origin)).then(async (res) => res.arrayBuffer()) - : await readFile(new URL(`.${fontPath}`, outDir)); + const url = experimental_getFontFileURL(fontPath, context.url); + const data = await fetch(url).then((res) => res.arrayBuffer()); const svg = await satori( html`<div style="color: black;">hello, world</div>`, { width: 600, height: 400, fonts: [ { name: "Roboto", data, weight: 400, style: "normal", }, ], }, ); const pngBuffer = await sharp(Buffer.from(svg)) .resize(600, 400) .png() .toBuffer(); return new Response(new Uint8Array(pngBuffer), { headers: { "Content-Type": "image/png", }, }); }; ``` See the [Fonts API documentation](https://docs.astro.build/en/guides/fonts/#accessing-font-data-programmatically) for more information. ##### Patch Changes - [#15980](withastro/astro#15980) [`8812382`](withastro/astro@8812382) Thanks [@seroperson](https://github.com/seroperson)! - Prevents script deduplication inside `<template>` elements </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - At any time (no schedule defined) - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).

github-actions Bot added pkg: astro Related to the core `astro` package (scope) docs pr labels Mar 18, 2026

seroperson force-pushed the i15389-template-script-dedup branch 2 times, most recently from 8a2e551 to a11ac94 Compare March 18, 2026 12:07

seroperson force-pushed the i15389-template-script-dedup branch 2 times, most recently from 866a50e to 949a1e1 Compare March 18, 2026 12:49

matthewp reviewed Mar 19, 2026

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Comment thread packages/astro/src/runtime/server/render/astro/render-template.ts Outdated

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seroperson mentioned this pull request Mar 19, 2026

feat: emit template depth tracking instructions withastro/compiler#1156

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seroperson force-pushed the i15389-template-script-dedup branch from 949a1e1 to 6202b78 Compare March 19, 2026 18:33

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seroperson mentioned this pull request Mar 29, 2026

feat: emit template depth tracking instructions withastro/compiler-rs#17

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fix: prevent script dedup inside <template>

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Closes withastro#15389

seroperson force-pushed the i15389-template-script-dedup branch from 1addff9 to 6a336b2 Compare March 31, 2026 15:12

Back to the instructions approach

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Princesseuh added this to the 6.2 milestone Apr 15, 2026

Princesseuh added 2 commits April 28, 2026 15:17

fix: update compiler

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Merge remote-tracking branch 'origin/main' into i15389-template-scrip…

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…t-dedup # Conflicts: # packages/astro/package.json # pnpm-lock.yaml

github-actions Bot added the semver: minor Change triggers a `minor` release label Apr 28, 2026

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fix: tests

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Comment thread .changeset/jolly-bars-play.md Outdated

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Princesseuh mentioned this pull request Apr 28, 2026

Add "jsx" option to compressHTML #15725

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seroperson and others added 2 commits April 29, 2026 03:37

Update .changeset/jolly-bars-play.md

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Co-authored-by: Armand Philippot <[email protected]>

Update .changeset/jolly-bars-play.md

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Co-authored-by: Erika <[email protected]>

Princesseuh merged commit 8812382 into withastro:main Apr 29, 2026
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astrobot-houston mentioned this pull request Apr 29, 2026

[ci] release #16512

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ocavue mentioned this pull request Apr 30, 2026

ocavue/get tsconfig 4 debug ocavue-forks/astro#31

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Version Packages withastro/compiler-rs#32

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