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Author	SHA1	Message	Date
Rich Harris	40f05ab9d3	update changeset	3 days ago
Rich Harris	95a0bec7c2	holy shit it woooooorks	3 days ago
Rich Harris	903eedb861	progress i think?	3 days ago
Rich Harris	dac3364087	Merge branch 'main' into each-block-pending	3 days ago
Rich Harris	0e8f49b25f	chore: rebase batches after process, not during (#17900) ... This is part of me trying to figure out #17162. It feels less confusing to rebase other branches after the current batch has been processed, rather than sort of doing it in the middle (which is an artifact of historical constraints that no longer apply). No test because it doesn't change any user-observable behaviour (but I added a changeset just in case) ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint`	3 days ago
github-actions[bot]	72cd247c33	Version Packages (#17896) ... This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.53.10 ### Patch Changes - fix: re-process batch if new root effects were scheduled ([#17895](https://github.com/sveltejs/svelte/pull/17895)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	3 days ago
Simon H	342d8568f1	fix: re-process batch if new root effects were scheduled (#17895) ... In some cases a new branch might create effects which via reading/writing reschedule an effect, causing `this.#roots` to become populated again. In this case we need to re-process the batch. Most of the time this will just result in a cleanup of the dirtied branches since other work is already handled via running the effects etc. - it's still crucial, else the reactive graph becomes frozen since no new root effects are scheduled. Fixes #17891 --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	3 days ago
Rich Harris	43ed2ba594	better test	3 days ago
Rich Harris	68fa3462dd	merge main	3 days ago
Rohan Santhosh	51d305d18a	docs: fix usable spelling in migration guide (#17889) ... ### Summary Fix spelling in the v5 migration guide ("useable" -> "usable"). ### Before submitting the PR, please make sure you do the following - [ ] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). (Not applicable; docs-only change.) ### Tests and linting - [ ] Run the tests with `pnpm test` and lint the project with `pnpm lint`. (Not run; docs-only change.) Co-authored-by: rohan436 <rohan.santhoshkumar@googlemail.com>	3 days ago
github-actions[bot]	d54361b97f	Version Packages (#17886) ... This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.53.9 ### Patch Changes - fix: better `bind:this` cleanup timing ([#17885](https://github.com/sveltejs/svelte/pull/17885)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	4 days ago
Simon H	be36c934c4	fix: better `bind:this` cleanup timing (#17885) ... This removes the `queue_micro_task`-workaround we employed in `bind:this` in favor of a search for the nearest component effect / effect that is still getting destroyed, whichever comes first. We used `queue_micro_task` mainly due to timing issues with components wanting to access the bound property on teardown still, and when nulling it out on cleanup of the bind-this-effect itself, that was too early. The microtask is too late though in some cases, when accessing properties of objects that are no longer there. The targeted upwards-walk solves this while keeping the binding around as long as needed. For that I had to add a new `DESTROYING` flag. We _could_ have done it without one and by deleting code in `props.js` where we don't do `get(d)` when the prop derived is destroyed, but I wanted to keep that because you could still run into an access error if you e.g. access the property in a timeout. Alternative to #17862	4 days ago
github-actions[bot]	d2b347042c	Version Packages (#17854) ... This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.53.8 ### Patch Changes - fix: `{@html}` no longer duplicates content inside `contenteditable` elements ([#17853](https://github.com/sveltejs/svelte/pull/17853)) - fix: don't access inert block effects ([#17882](https://github.com/sveltejs/svelte/pull/17882)) - fix: handle asnyc updates within pending boundary ([#17873](https://github.com/sveltejs/svelte/pull/17873)) - perf: avoid re-traversing the effect tree after `$:` assignments ([#17848](https://github.com/sveltejs/svelte/pull/17848)) - chore: simplify scheduling logic ([#17805](https://github.com/sveltejs/svelte/pull/17805)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	4 days ago
Paolo Ricciuti	ef95f34ae1	docs: add skill true frontmatter (#17877) ... This adds a `skill: true` to the frontmatter of the bestpractices skill/doc. This way when we sync we can concern ourselves to only the documents that need to be skills (we will write one for sveltekit too) without targeting specific files in the `ai-tools` repo	4 days ago
Simon H	1892988074	fix: don't access inert block effects (#17882) ... In #17837 we added logic to not schedule another batch during resumption. The logic in there turns out to be flawed - it's dangerous to keep accessing inert block effects, because if they're nested they could access properties that no longer exist (because the outer if makes the inner if obsolete). So this PR basically reverts #17837 and instead schedules another batch again under the assumption that this will only happen during the commit phase, and all that's gonna happen is that it will schedule another batch, which is safe. Fixes #17866 Fixes #17878 This reverts commit 2f12b60701. Co-authored-by: Rich Harris <rich.harris@vercel.com>	4 days ago
Simon H	1304208970	fix: set deferreds on initial suspense, too (#17884) ... The combination of #17873 and #17805 resulted in a bad merge of the latter because it wasn't up to date with main. This fixes it. No changeset because not released yet. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	4 days ago
Rich Harris	6fb7b4d265	chore: refactor scheduling (#17805) ... This simplifies the scheduling logic and will likely improve performance in some cases. Previously, there was a global `queued_root_effects` array, and we would cycle through the batch flushing logic as long as it was non-empty. This was a very loosey-goosey approach that was appropriate in the pre-async world, but has gradually become a source of confusion. Now, effects are scheduled within the context of a specific batch. The lifecycle is more rigorous and debuggable. This opens the door to explorations of alternative approaches, such as only scheduling effects when we call `batch.flush()`, which _may_ be better than the eager status quo. The layout of the `Batch` class is extremely chaotic — public/private/static fields/methods are all jumbled up together — and I would like to get a grip of it. In the interests of minimising diff noise that ought to be a follow-up rather than part of this PR. ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>	5 days ago
Simon H	2deebdea8f	fix: handle asnyc updates within pending boundary (#17873) ... When an async value is updated inside the boundary while the pending snippet is shown, we previously didn't notice that update and instead showed an outdated value once it resolved. This fixes that by rejecting all deferreds inside an async_derived while the pending snippet is shown. --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	7 days ago
dev-miro26	0206a2019e	fix: clean up externally-added DOM nodes in {@html} on re-render (#17853) ... Fixes `{@html}` content duplication when used inside a contenteditable element. When `{@html content}` is inside a contenteditable element and the user types, the browser inserts DOM nodes directly into the {@html} managed region. On re-render (e.g. triggered by a blur handler setting `content = e.currentTarget.innerText`, the `{@html} `block only removed nodes it previously created via` effect.nodes`, leaving browser-inserted nodes in place. This caused content to appear twice — once as leftover text nodes and once as the new `{@html}` output. The fix tracks the boundary node (`previousSibling `of the anchor at init) and removes all nodes between the boundary and the anchor on re-render, ensuring externally-added nodes are also cleaned up. Closes: #16993 --------- Co-authored-by: 7nik <kfiiranet@gmail.com> Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>	7 days ago
Rich Harris	3df2645451	chore: deactivate batch after async derived resolves (#17865) ... Extracted from #17805. Similar to #17864, I'm not aware of any bugs resulting from this, but the fact that we're setting `current_batch` before calling `internal_set` and then not _unsetting_ `current_batch` feels like something that could potentially bite us.	7 days ago
Rich Harris	2a1f5ada13	perf: avoid re-traversing the effect tree after `$:` assignments (#17848) ... If an assignment happens in a `$:` statement, any affected effects are rescheduled while the traversal is ongoing. But this is wasteful — it results in the `flush_effects` loop running another time, even though the affected effects are guaranteed to be visited _later_ in the traversal (unless the thing being updated is a store). This PR fixes it: inside a `legacy_pre_effect`, we temporarily pretend that the branch _containing_ the component with the `$:` statement is the `active_effect`, such that Svelte understands that any marked effects are about to be visited and thus don't need to be scheduled. We deal with the store case by temporarily pretending that there _is_ no `active_effect`. I will be delighted when we can rip all this legacy stuff out of the codebase. ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint`	1 week ago
Rich Harris	7dc864d941	Revert "fix: skip derived re-evaluation inside inert effect blocks" (#17869) ... Reverts sveltejs/svelte#17852, because it isn't a real fix https://github.com/sveltejs/svelte/pull/17868	1 week ago
Rich Harris	aed36051fd	chore: robustify `flatten` (#17864) ... Extracted from #17805. Currently we restore context in`flatten` unnecessarily in the case where we have async expressions but no blockers (the context is already correct), and we don't unset context after blockers resolve in the case where we have them. The first bit is suboptimal, but the second bit feels bug-shaped, even though I'm not currently aware of any actual bugs that have resulted from this. ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint`	1 week ago
Rich Harris	9066b75c01	chore: tidy up (#17863) ... small tweaks, will self-merge	1 week ago
dependabot[bot]	61a443f1fa	chore(deps): bump immutable from 4.3.7 to 4.3.8 (#17860) ... Bumps [immutable](https://github.com/immutable-js/immutable-js) from 4.3.7 to 4.3.8. <details> <summary>Release notes</summary> <p><em>Sourced from <a href="https://github.com/immutable-js/immutable-js/releases">immutable's releases</a>.</em></p> <blockquote> <h2>v4.3.8</h2> <p>Fix Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable</p> </blockquote> </details> <details> <summary>Changelog</summary> <p><em>Sourced from <a href="https://github.com/immutable-js/immutable-js/blob/main/CHANGELOG.md">immutable's changelog</a>.</em></p> <blockquote> <h1>Changelog</h1> <p>All notable changes to this project will be documented in this file.</p> <p>The format is based on <a href="https://keepachangelog.com/en/1.0.0/">Keep a Changelog</a>, and this project adheres to <a href="https://semver.org/spec/v2.0.0.html">Semantic Versioning</a>. Dates are formatted as YYYY-MM-DD.</p> <h2>Unreleased</h2> <h2>5.1.5</h2> <ul> <li>Fix Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable</li> </ul> <h2>5.1.4</h2> <ul> <li>Migrate some files to TS by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2125">immutable-js/immutable-js#2125</a> <ul> <li>Iterator.ts</li> <li>PairSorting.ts</li> <li>toJS.ts</li> <li>Math.ts</li> <li>Hash.ts</li> </ul> </li> <li>Extract CollectionHelperMethods and convert to TS by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2131">immutable-js/immutable-js#2131</a></li> <li>Use npm <a href="https://docs.npmjs.com/trusted-publishers">trusted publishing only</a> to avoid token stealing.</li> </ul> <h3>Documentation</h3> <ul> <li>Fix/a11y issues by <a href="https://github.com/lyannel"><code>@​lyannel</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2136">immutable-js/immutable-js#2136</a></li> <li>Doc add Map.get signature update by <a href="https://github.com/borracciaBlu"><code>@​borracciaBlu</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2138">immutable-js/immutable-js#2138</a></li> <li>fix(doc):minor-issues#2132 by <a href="https://github.com/JayMeDotDot"><code>@​JayMeDotDot</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2133">immutable-js/immutable-js#2133</a></li> <li>Fix algolia search by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2135">immutable-js/immutable-js#2135</a></li> <li>Typo in OrderedMap by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2144">immutable-js/immutable-js#2144</a></li> </ul> <h3>Internal</h3> <ul> <li>chore: Sort all imports and activate eslint import rule by <a href="https://github.com/jdeniau"><code>@​jdeniau</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2119">immutable-js/immutable-js#2119</a></li> </ul> <h2>5.1.3</h2> <h3>TypeScript</h3> <ul> <li>fix: allow readonly map entry constructor by <a href="https://github.com/septs"><code>@​septs</code></a> in <a href="https://redirect.github.com/immutable-js/immutable-js/pull/2123">immutable-js/immutable-js#2123</a></li> </ul> <h3>Documentation</h3> <p>There has been a huge amount of changes in the documentation, mainly migrate from an autogenerated documentation from .d.ts file, to a proper documentation in markdown. The playground has been included on nearly all method examples. We added a page about browser extensions too: <a href="https://immutable-js.com/browser-extension/">https://immutable-js.com/browser-extension/</a></p> <h3>Internal</h3> <!-- raw HTML omitted --> </blockquote> <p>... (truncated)</p> </details> <details> <summary>Commits</summary> <ul> <li><a href="485cbe0edf"><code>485cbe0</code></a> 4.3.8</li> <li><a href="6ed4eb6269"><code>6ed4eb6</code></a> Merge commit from fork</li> <li><a href="94bcd3c799"><code>94bcd3c</code></a> fix new proto key injection</li> <li><a href="faeb58b0cc"><code>faeb58b</code></a> fix Prototype Pollution in mergeDeep, toJS, etc.</li> <li>See full diff in <a href="https://github.com/immutable-js/immutable-js/compare/v4.3.7...v4.3.8">compare view</a></li> </ul> </details> <details> <summary>Maintainer changes</summary> <p>This version was pushed to npm by [GitHub Actions](<a href="https://www.npmjs.com/~GitHub">https://www.npmjs.com/~GitHub</a> Actions), a new releaser for immutable since your current version.</p> </details> <br /> [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) You can disable automated security fix PRs for this repo from the [Security Alerts page](https://github.com/sveltejs/svelte/network/alerts). </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	1 week ago
Rich Harris	e3f06f9fc7	fix: skip derived re-evaluation inside inert effect blocks (#17852) ... this is #17850 with changes (for whatever reason I wasn't able to push direct to the fork) — same test but simplified, and a simpler fix that doesn't undo the recent (necessary!) changes to the scheduling logic --------- Co-authored-by: Mattias Granlund <mtsgrd@gmail.com>	1 week ago
github-actions[bot]	25a1c5368b	Version Packages (#17842) ... This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.53.7 ### Patch Changes - fix: correctly add \_\_svelte_meta after else-if chains ([#17830](https://github.com/sveltejs/svelte/pull/17830)) - perf: cache element interactivity and source line splitting in compiler ([#17839](https://github.com/sveltejs/svelte/pull/17839)) - chore: avoid rescheduling effects during branch commit ([#17837](https://github.com/sveltejs/svelte/pull/17837)) - perf: optimize CSS selector pruning ([#17846](https://github.com/sveltejs/svelte/pull/17846)) - fix: preserve original boundary errors when keyed each rows are removed during async updates ([#17843](https://github.com/sveltejs/svelte/pull/17843)) - perf: avoid O(n²) name scanning in scope `generate` and `unique` ([#17844](https://github.com/sveltejs/svelte/pull/17844)) - fix: preserve each items that are needed by pending batches ([#17819](https://github.com/sveltejs/svelte/pull/17819)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	1 week ago
Philip Breuer	b7bc1309aa	fix: preserve original boundary errors when keyed each rows are removed during async updates (#17843) ... Fixes a runtime edge case where keyed #each reconciliation can hit a missing item during deferred async updates, causing an internal crash and masking the original boundary error. Fixes #17841 ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [x] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	1 week ago
Mathias Picker	0965028d3b	perf: optimize CSS selector pruning (#17846) ... ## Summary Reduces CSS selector pruning overhead by eliminating unnecessary allocations and redundant work in the hot path. **Changes:** - Replace `.slice()` + `.shift()`/`.pop()` in `apply_selector` with index-based `from`/`to` params — avoids O(n) array copies per recursive call - Merge `has_selectors`/`other_selectors` split in `relative_selector_might_apply_to_node` into a single pass — eliminates 2 temporary array allocations per call - Hoist `name.toLowerCase()` out of the inner loop in `attribute_matches` - Replace `value.split(/\s/).includes()` with `indexOf` + boundary checks in `test_attribute` for `~=` — avoids array allocation on every class match - Skip `name.replace()` regex when selector name has no backslash ## Benchmark Interleaved benchmark (5 rounds, alternating baseline/optimized): ``` --- Round 1 --- Baseline: min=59.58ms median=64.63ms Optimized: min=47.20ms median=54.35ms --- Round 2 --- Baseline: min=59.11ms median=64.90ms Optimized: min=48.36ms median=54.74ms --- Round 3 --- Baseline: min=58.38ms median=64.06ms Optimized: min=48.38ms median=53.83ms --- Round 4 --- Baseline: min=58.49ms median=63.99ms Optimized: min=48.45ms median=53.82ms --- Round 5 --- Baseline: min=58.40ms median=64.07ms Optimized: min=48.97ms median=54.64ms Best min: Before=58.38ms After=47.20ms Improvement=19.1% Best median: Before=63.99ms After=53.82ms Improvement=15.9% ``` CPU profile before → after: | Function | Before | After | |---|---|---| | `relative_selector_might_apply_to_node` | 14.3% | 5.2% | | `attribute_matches` | 4.0% | 3.3% | | `test_attribute` | 3.2% | <0.9% | ## Test plan - [x] All 196 CSS tests pass (180 samples + 16 parse) - [x] All 31 snapshot tests pass - [x] All 2380 runtime-runes tests pass - [x] All 3291 runtime-legacy tests pass - [x] All 145 compiler-errors tests pass - [x] All 326 validator tests pass - [x] Added `css-prune-edge-cases` test covering: `~=` word matching (substring vs whole word), deep combinator chains (4+ levels), `:has()` combined with class selectors, escaped selectors, `:is()`/`:where()`/`:not()` with combinators - [x] Edge case test passes on both baseline and optimized code 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com> Co-authored-by: Rich Harris <rich.harris@vercel.com>	1 week ago
Mathias Picker	32111f9e84	perf: avoid O(n²) name scanning in scope generate/unique (#17844) ... ## Summary `Scope.generate()` and `ScopeRoot.unique()` search for available names by iterating from suffix `_1` upward. When the same preferred name is generated many times (e.g. `text` is generated 482 times in a large component), the Nth call re-scans all N-1 already-taken names — O(n²) total work. This adds a `#name_counters` Map to `ScopeRoot` that tracks the next suffix to try per name, so each call resumes from where the last one left off. Generated names are identical to before. ## Benchmark (interleaved, best-of-3 rounds) | Component | Min | Median | |---|---|---| | Realistic (~80 lines) | ~1% | ~7% | | Medium (316 lines) | ~1% | ~5% | | Large (642 lines) | ~7% | ~2% | | XLarge (1302 lines) | **~11%** | **~10%** | ## Test plan - [x] All snapshot tests pass (name generation unchanged) - [x] All validator, compiler-error, runtime-runes, runtime-legacy tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	1 week ago
Rich Harris	2f12b60701	chore: avoid reschedule during branch commit (#17837) ... If a dirty effect is resumed — for example `condition` becomes `false` then `count` changes then `condition` becomes `true` again... ```svelte {#if condition} <div transition:fade> {count} </div> {/if} ``` ...then the effect is rescheduled. This happens when branches are committed (after the effect tree is traversed, before effects are flushed). That's undesirable, because it causes another turn of the `flush_effects` loop. It's better if we can handle everything in a single pass, which is what happens in this PR. The trade-off is that we have to traverse the entire effect tree, instead of skipping inert subtrees, which is a trade-off that I think makes sense. The real agenda here is that I'm trying to eliminate all `schedule_effect` calls that happen at inconvenient times, because I have a hunch that if we do that we can return to #17805, which I'm increasingly convinced will be important. (You might have to trust me on this; a full explanation would look a bit charlie-day-meme.jpg. Call it a hunch.) ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>	2 weeks ago
Rich Harris	00dc13db14	chore: highlight effect in tree (#17835) ... Another QoL improvement to `log_effect_tree` — if you pass an array of effects as the second argument, it will highlight them in the tree. It will also italicise any effects that currently have the `INERT` flag.	2 weeks ago
Rich Harris	86ec210866	fix: correctly add `__svelte_meta` after else-if chains (#17830) ... While looking into something else I spotted the fact that we use `false` to indicate 'else' in an `{#if ...}` block (whether there's an `else` block to render or not). If we instead use `-1`, and use `<!--[0-->` to indicate that the first block in an if-elseif chain was rendered... - instead of `<!--[-->`, we do `<!--[0-->` - instead of `<!--[!-->`, we do `<!--[-1-->` - all others stay the same ...we can simplify things a bit — the `key` argument to `update_branch` is always a number (which probably has some microscopic benefits in terms of making it monomorphic when `else` is defined, and less polymorphic when it isn't), and the hydration mismatch code only needs to consider one type of hydration marker. In the process, I discovered a bug — the dev-time `add_locations` function fails on hydration markers like `<!--[1-->`. This PR fixes it.	2 weeks ago
Rich Harris	7717ba01b4	fix: preserve each items that are needed by pending batches (#17819) ... This fixes a longstanding TODO with each blocks: currently, if any effects aren't used in the current batch at the moment of reconciliation, they are destroyed. Subsequent batches therefore end up recreating them. This is wasteful at the best of times, but if the effect contains any async work, that work has to be restarted. This PR fixes it by preserving any effects that correspond to the keys of pending batches. It _does_ mean that we need to iterate over each `keys` map for each pending batch in which an each block re-ran, but that is a rare scenario. This feels preferable to the alternative approaches.	2 weeks ago
Mathias Picker	791d5e332c	perf: cache element interactivity and source line splitting (#17839) ... ## Summary Two small compiler optimizations that reduce redundant work: - **Cache `element_interactivity` per element in a11y checks**: `check_element` was calling `element_interactivity()` up to 10 times per element (via `is_interactive_element`, `is_non_interactive_element`, `is_static_element` wrappers), each time re-iterating schema arrays. Now computed once after building the attribute map and reused. The now-unused wrapper functions are removed. - **Split source lines once in `state.set_source`**: Every compiler warning called `get_code_frame` which split the entire source string with `source.split('\n')`. Now the split happens once in `set_source()` and is exported as `state.source_lines`, naturally cleared by `reset()`. ## Benchmark Synthetic component (80 state vars, 30 each blocks, ~1300 lines): ``` Min Best3 Median Before 66.55ms 67.03ms 73.44ms After 61.14ms 61.90ms 70.63ms Improvement 8.1% 7.7% 3.8% ``` Realistic component (~80 lines, ~25 elements, few warnings): **~1-4%** improvement. The a11y cache scales with element count, the source.split saving scales with warning count. ## Test plan - [x] All 326 validator tests pass (includes all a11y tests) - [x] All 5671 runtime tests pass - [x] 145 compiler-error tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	4aa3777271	chore: better log_effect_tree (#17833) ... While working on the reactivity it's very helpful to be able to log a snapshot of the effect tree. This PR augments the existing `log_effect_tree` helper by marking unreachable-but-dirty effects, like so: <img width="333" height="415" alt="image" src="https://github.com/user-attachments/assets/2c7501f7-b845-4271-b534-3a8be0ff62ee" /> (I had thought `log_inconsistent_branches` was designed to help with this but it didn't work for me. Do we need both? cc @dummdidumm) --------- Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>	2 weeks ago
Rich Harris	15e1e73f9c	chore: add `batch.id` property (#17831) ... I cannot tell you how many times I have temporarily added this code to make it easier to debug some async stuff. I am extremely bored of doing so. I'm just going to add it to `main` to save myself the annoyance. We can remove it once everything async is stable	2 weeks ago
Rich Harris	a02b1c4dbc	Merge branch 'async-each-preserve-pending' into each-block-pending	2 weeks ago
Rich Harris	b17330ec1b	Merge branch 'main' into async-each-preserve-pending	2 weeks ago
github-actions[bot]	d4c78292ed	Version Packages (#17812) ... This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.53.6 ### Patch Changes - perf: optimize parser hot paths for faster compilation ([#17811](https://github.com/sveltejs/svelte/pull/17811)) - fix: `SvelteMap` incorrectly handles keys with `undefined` values ([#17826](https://github.com/sveltejs/svelte/pull/17826)) - fix: SvelteURL `search` setter now returns the normalized value, matching native URL behavior ([#17828](https://github.com/sveltejs/svelte/pull/17828)) - fix: visit synthetic value node during ssr ([#17824](https://github.com/sveltejs/svelte/pull/17824)) - fix: always case insensitive event handlers during ssr ([#17822](https://github.com/sveltejs/svelte/pull/17822)) - chore: more efficient effect scheduling ([#17808](https://github.com/sveltejs/svelte/pull/17808)) - perf: optimize compiler analysis phase ([#17823](https://github.com/sveltejs/svelte/pull/17823)) - fix: skip redundant batch.apply ([#17816](https://github.com/sveltejs/svelte/pull/17816)) - chore: null out current_batch before committing branches ([#17809](https://github.com/sveltejs/svelte/pull/17809)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2 weeks ago
Rich Harris	1b68706e6e	Merge branch 'main' into each-block-pending	2 weeks ago
Mathias Picker	361b32c7cd	fix: SvelteURL search setter uses unnormalized value (#17828) ... ## Summary - The `SvelteURL` `search` setter stored the raw input `value` instead of `super.search`, unlike every other setter in the class - This caused `url.search` to return incorrect values when the URL API normalizes the input (e.g. adding the `?` prefix, or stripping a lone `?`) - For example: `url.search = 'foo=bar'` would return `'foo=bar'` instead of `'?foo=bar'` ## Test plan - [x] Added `url.search normalizes value` test covering: - Setting search without `?` prefix - Setting search with `?` prefix (existing behavior) - Setting search to lone `?` (normalized to `""`) - [x] All existing reactivity tests pass (46/46) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	6e9b2a6fd8	docs: best practices (#17804) ... Based on #17727 but with a few changes: - smaller (fewer tokens) - removed some bits that are really just summarising existing docs - added an explicit 'don't use these legacy features' section - shuffled some things around a bit --------- Co-authored-by: paoloricciuti <ricciutipaolo@gmail.com> Co-authored-by: Federico Varano <50919335+fvarano@users.noreply.github.com> Co-authored-by: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>	2 weeks ago
Mathias Picker	1043f79d1e	perf: optimize compiler analysis phase (#17823) ... ## Summary Two optimizations to the compiler's analysis phase: - **Cache `ignore_stack` snapshots instead of `structuredClone` on every node.** The universal `_` visitor in the analysis walk runs on every AST node and calls `structuredClone(ignore_stack)` each time. In practice, `svelte-ignore` comments are rare (0–5 per component), so 99%+ of nodes deep-clone an unchanged stack. This adds a copy-on-write cache that only re-creates the snapshot when `push_ignore`/`pop_ignore` actually change the stack. - **Walk the CSS stylesheet once instead of once per element.** `prune()` was called in a loop for each element, each time doing a full `walk()` of the stylesheet AST. This restructures the loop so the stylesheet is walked once, and the element iteration happens inside the `ComplexSelector` visitor. ## Benchmarks Compiled each component 500 times (after 50 warmup iterations), measuring average time per `compile()` call: | Component | Before | After | Speedup | |---|---|---|---| | `has` (80+ CSS selectors, 12 elements) | 3.405 ms | 2.680 ms | **21% faster** | | `siblings-combinator-each-nested` (65 CSS rules, 15 elements) | 2.034 ms | 1.575 ms | **23% faster** | | synthetic (100 CSS rules, 50 elements) | 10.099 ms | 4.564 ms | **55% faster** | The CSS pruning optimization scales with `elements × CSS rules` — the more elements a component has, the bigger the win since we go from N stylesheet walks down to 1. The `structuredClone` fix helps every component regardless of CSS, eliminating ~500–2000 deep clones per compile (one per AST node) and replacing them with 0–5 (one per `svelte-ignore` comment). For typical real-world components with 10–20 elements and some CSS, expect roughly **20–30% faster compilation** in the analysis phase. ## Test plan - [x] Full test suite passes (7329 tests, 0 failures) - [x] CSS pruning tests pass (selector matching, scoping, unused rule detection) - [x] `svelte-ignore` behavior unchanged (snapshot is consumed read-only via `.has()`/`.some()`) 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Paolo Ricciuti	b6faa2a905	fix: always case insensitive event handlers during ssr (#17822) ... Fixes events not being stripped on svg, mathml and custom elements. ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [x] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>	2 weeks ago
Paolo Ricciuti	e3d277b000	fix: visit synthetic value node during ssr (#17824) ... Closes #17821 ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [x] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint`	2 weeks ago
Tee Ming	a10cf95ca7	chore: add funding manifest URL (#17827) ... Related to https://github.com/sveltejs/svelte.dev/pull/1632 This will allow us to apply for a grant from floss.fund ### Before submitting the PR, please make sure you do the following - [ ] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [ ] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [ ] This message body should clearly illustrate what problems it solves. - [ ] Ideally, include a test that fails without this PR but passes with it. - [ ] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [ ] Run the tests with `pnpm test` and lint the project with `pnpm lint`	2 weeks ago
Mathias Picker	18db0cab86	fix: SvelteMap incorrectly handles keys with `undefined` values (#17826) ... ## Summary `SvelteMap` had two bugs related to how it checked for key existence internally: ### 1. `has()` and `get()` returned wrong results for keys with `undefined` values Both methods used `super.get(key) !== undefined` to determine if a key existed before creating a per-key reactive source. This fails for keys whose value is legitimately `undefined`, causing: - `has(key)` to return `false` for existing keys with `undefined` values - `get(key)` to skip creating a per-key source and fall back to tracking `version`, resulting in over-notification **Fix:** Replace `super.get(key) !== undefined` with `super.has(key)` in both `has()` and `get()`, matching the pattern already used in `SvelteSet`. ### 2. `delete()` skipped reactive updates when a key had no per-key source The `size` and `version` reactive updates were inside the `if (s !== undefined)` block, meaning they only fired when a per-key source existed (i.e., someone had previously called `has()` or `get()` on that specific key). If a key was added via the constructor or `set()` but never individually read, deleting it would not trigger reactive updates for effects depending on `size` or iterators. **Fix:** Move `set(this.#size, super.size)` and `increment(this.#version)` to a separate `if (res)` block so they fire whenever a key is actually deleted, regardless of whether a per-key source existed. ### Before fix ```js const map = new SvelteMap([['foo', undefined]]); map.has('foo'); // false (should be true) map.get('foo'); // undefined but tracks version instead of per-key source ``` ### After fix ```js const map = new SvelteMap([['foo', undefined]]); map.has('foo'); // true map.get('foo'); // undefined with correct per-key tracking ``` ## Test plan Tests are in `packages/svelte/src/reactivity/map.test.ts`: - `map.has()` returns `true` for constructor-initialized keys with `undefined` values - `map.get()` returns `undefined` with proper per-key reactive tracking - `map.delete()` triggers `has()`/`get()` reactivity for undefined-valued keys - `map.set(key, undefined)` followed by `has()`/`get()` works correctly - `map.delete()` triggers `size` reactivity for keys that were never individually read (no per-key source) - All existing tests pass unchanged 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2 weeks ago
Rich Harris	3fc4bc6774	chore: remove unused is_flushing variable (#17820) ... as of a few PRs ago this variable is unused	2 weeks ago
Rich Harris	2cb3759e47	fix test	2 weeks ago