Sandbox::https://github.com/unjs/unhead/pull/1064

harlan-zw · 2026-11-10T03:16:24Z

🔗 Linked issue

❓ Type of change

📖 Documentation (updates to the documentation or readme)
🐞 Bug fix (a non-breaking change that fixes an issue)
👌 Enhancement (improving an existing functionality)
✨ New feature (a non-breaking change that adds functionality)
🧹 Chore (updates to the build process or auxiliary tools and libraries)
⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

processTemplateParams runs decodeURI on each string that contains %, so a URL-encoded value is not read as a token. decodeURI throws when two hex digits do not follow a %. Every string with a token such as %s or %siteName has one, so each call threw and caught a URIError.

The function now tests for that % first and skips the decode. The output does not change, because the catch already fell back to the original string. A string with only valid encodings, such as some%20image.jpg, still decodes.

Results from packages/unhead/test/unit/templateParams.bench.ts, in ops/s, over three runs on each side:

Case	`main`	This branch
`basic` (`%s %separator %siteName`)	278k to 281k	2.10M to 2.12M
`nested props`	290k to 291k	2.58M to 2.60M
`not found props`	285k to 288k	2.29M to 2.33M
`with url` (valid encodings only)	7.63M to 8.55M	7.21M to 7.33M
`simple string` (no `%`)	35.2M to 36.3M	35.0M to 36.2M

The with url case runs the new test and still decodes, so it is about 10% slower.

On a bare Nuxt nightly app, server requests per second rose 7.2 to 10.7% on six routes, and head render time fell 25 to 37%. That run used a build of the feat/compiled-server-head branch (#1062) with the compiled head off. The run was not repeated on main.

🤖 AI disclosure: Harlan Agent Kit modified this description. My AI open-source policy.

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Template parameter processing now preserves literal percent signs and malformed or invalid encoded sequences instead of attempting to decode them. Valid encoded URLs continue to be decoded, and valid template tokens are still resolved, including when they appear next to encoded values.

decodeURI throws when two hex digits do not follow a `%`. Every string with a template token has such a `%`, so each call to processTemplateParams threw and caught a URIError before it matched tokens. The catch already fell back to the original string, so a test for that `%` gives the same output without the throw. Co-Authored-By: Claude <noreply@anthropic.com>

coderabbitai · 2026-11-10T03:16:38Z

Walkthrough

processTemplateParams now skips decodeURI when its input contains a percent sign that is not followed by two hexadecimal digits. Tests cover encoded values, literal percent signs, invalid UTF-8 bytes, and template token resolution.

Changes: Template parameter decoding

Layer / File(s)	Summary
Guard URI decoding and verify substitutions `packages/unhead/src/utils/templateParams.ts`, `packages/unhead/test/unit/server/templateParams.test.ts`	`processTemplateParams` checks for malformed percent escapes before attempting `decodeURI`. Tests verify that encoded values and literal percent signs are preserved while `%siteName` resolves to `My Site`.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Possibly related PRs

unjs/unhead#1039: Changes JSON escaping for replacement values in processTemplateParams, another stage of template-parameter substitution.

Suggested reviewers: henricop

Merge Risk: Minimal · up to 1b296

No merge-blocking risk is apparent from the supplied evidence.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description check		The description includes the required sections, identifies the change as an enhancement, explains the problem and solution, and provides benchmark results with relevant caveats.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly describes the main change: avoiding a decodeURI error in template parameters.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 1 functions across 2 files.

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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harlan-zw · 2026-11-10T03:19:57Z

🤖 MERGED

Harlan Agent Kit posted this automated review. It is not Harlan's personal review or approval. AI open source policy. Last updated: 2026-11-10 03:33 UTC.

GitHub merged this pull request.

No material findings were recorded.

b9b769f4-0c2b-4a75-857d-7b6f8e166b92

github-actions · 2026-11-10T03:20:38Z

📦 Bundle Size

⚠️ 1 bundle grew · net +21 B gz

Bundle	Gzipped	Δ
Schema.org (Minimal)	13.4 kB → 13.4 kB	🔴 +21 B (+0.2%)

All bundles (14)

Bundle	Gzipped	Brotli	Raw
Core
Client (Minimal)	5.4 kB	4.9 kB	13.4 kB	✅
Client (Full)	9.8 kB	8.9 kB	25.5 kB	✅
Client (Self-Contained)	5.7 kB	5.1 kB	14.2 kB	✅
Server (Minimal)	4.9 kB	4.4 kB	12.4 kB	✅
Server (Self-Contained)	5.2 kB	4.7 kB	13.1 kB	✅
Vue
Vue Client (Minimal)	5.9 kB	5.3 kB	14.5 kB	✅
Vue Client (Full)	10.9 kB	9.9 kB	28.5 kB	✅
Vue Server (Minimal)	5.4 kB	4.9 kB	13.4 kB	✅
React
React Client (Minimal)	5.8 kB	5.3 kB	14.6 kB	✅
React Client (Full)	10.9 kB	9.9 kB	28.7 kB	✅
React Server (Minimal)	5.2 kB	4.7 kB	13 kB	✅
Schema.org
Schema.org (Minimal)	13.4 kB	12 kB	39.1 kB	🔴
Schema.org Imports	0.1 kB	0.1 kB	0.1 kB	✅
Schema.org Vue Meta	0.5 kB	0.4 kB	1 kB	✅

📦 Runtime Dependencies

✅ No runtime dependency changes

All packages (10)

Package	External deps	Install size	Largest dependency	Skipped optional
@unhead/angular	10	784 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/bundler	10	811 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/cli	18	4.5 MB	@oxc-parser/binding-linux-arm64-gnu 2 MB	18
@unhead/eslint-plugin	9	693.6 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/react	11	834.9 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/schema-org	9	693.6 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/solid-js	11	834.9 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/svelte	11	834.9 kB	@jridgewell/trace-mapping 146.7 kB	0
@unhead/vue	11	834.9 kB	@jridgewell/trace-mapping 146.7 kB	0
unhead	9	693.6 kB	@jridgewell/trace-mapping 146.7 kB	0

Skipped optional dependencies (18)

@unhead/cli: oxc-parser -> @oxc-parser/binding-android-arm-eabi, oxc-parser -> @oxc-parser/binding-android-arm64, oxc-parser -> @oxc-parser/binding-darwin-arm64, oxc-parser -> @oxc-parser/binding-darwin-x64, oxc-parser -> @oxc-parser/binding-freebsd-x64, oxc-parser -> @oxc-parser/binding-linux-arm-gnueabihf, oxc-parser -> @oxc-parser/binding-linux-arm-musleabihf, oxc-parser -> @oxc-parser/binding-linux-arm64-musl, oxc-parser -> @oxc-parser/binding-linux-ppc64-gnu, oxc-parser -> @oxc-parser/binding-linux-riscv64-gnu, oxc-parser -> @oxc-parser/binding-linux-riscv64-musl, oxc-parser -> @oxc-parser/binding-linux-s390x-gnu, oxc-parser -> @oxc-parser/binding-linux-x64-gnu, oxc-parser -> @oxc-parser/binding-linux-x64-musl, oxc-parser -> @oxc-parser/binding-openharmony-arm64, oxc-parser -> @oxc-parser/binding-win32-arm64-msvc, oxc-parser -> @oxc-parser/binding-win32-ia32-msvc, oxc-parser -> @oxc-parser/binding-win32-x64-msvc

_{Production dependencies only. Peer dependencies and Unhead workspace packages are excluded. Skipped optional dependencies are unavailable on the CI platform.}

⚡ Performance (directional)

✅ No significant change (within CI noise)

All benchmarks (25)

Benchmark	PR	Δ	RME
SSR render (CPU)	0.363 ms	~ noise	±9.5%
SSR render (wall)	0.265 ms	~ noise	±4.9%
SSR allocated / render	247.6 KiB	~ noise	±1.9%
Schema.org cached render (CPU)	0.321 ms	~ noise	±6.8%
Schema.org cached render (wall)	0.227 ms	ℹ️ -12.8%	±3.7%
Schema.org cached allocated / render	128.6 KiB	~ noise	±3.0%
Streaming wrapStream drain (CPU)	0.215 ms	~ noise	±5.3%
Streaming wrapStream drain (wall)	0.117 ms	~ noise	±6.0%
Streaming allocated / drain	109.3 KiB	~ noise	±0.5%
Streaming suspense chunk (CPU)	0.015 ms	~ noise	±10.8%
Streaming allocated / suspense chunk	4.9 KiB	~ noise	±0.3%
CSR DOM mutations / nav	38	~ noise	—
CSR re-render (CPU)	1.039 ms	~ noise	±4.6%
CSR re-render (wall)	0.588 ms	~ noise	±2.3%
Bundler: ssrStaticReplace skip unrelated code	0.002 ms	~ noise	±1.3%
Bundler: treeshakeServerComposables skip unrelated code	0.002 ms	~ noise	±1.6%
Bundler: solid streaming skip JSX without head calls	0.003 ms	~ noise	±0.8%
Bundler: react streaming skip JSX without head calls	0.003 ms	~ noise	±0.7%
Bundler: transform id filter mixed ids	0.203 ms	~ noise	±0.5%
Bundler: minifyTransform inline script/style	0.503 ms	~ noise	±2.4%
Bundler: createHeadTransform many createHead calls	0.569 ms	~ noise	±3.9%
Bundler: react streaming transform JSX with head calls	1.586 ms	~ noise	±5.2%
Bundler: ssrStaticReplace many head.ssr reads	1.639 ms	~ noise	±5.4%
Bundler: treeshakeServerComposables many calls	2.716 ms	~ noise	±4.8%
Bundler: useSeoMetaTransform static calls	3.550 ms	~ noise	±3.5%

_{Baseline: main @ b2f15a4 · 2026-11-07 · gzipped is the headline size metric · perf is directional (shared-runner, gated)}

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Reviewing files that changed from the base of the PR and between `b2f15a4` and `1b2967a`.

Files selected for processing: 2

`packages/unhead/src/utils/templateParams.ts`

`packages/unhead/test/unit/server/templateParams.test.ts`

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harlan-zw removed the harlan-agent-running An Agent holds a Task on this issue or pull request right now. label Nov 10, 2026

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harlan-zw changed the title ~~perf(unhead): avoid the decodeURI throw in template params~~ perf: avoid the decodeURI throw in template params Nov 10, 2026

harlan-zw merged commit 03db60d into main Nov 10, 2026
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perf: avoid the decodeURI throw in template params - #1064

perf: avoid the decodeURI throw in template params#1064
harlan-zw merged 1 commit into
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perf/template-params-decode-guard

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📦 Bundle Size

📦 Runtime Dependencies

⚡ Performance (directional)

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