## [1.0.0-rc.16] - 2026-04-16

### 🚀 Features

- const enum cross-module inlining support (#8796) by @Dunqing
- implement module tagging system for code splitting (#9045) by @hyf0

### 🐛 Bug Fixes

- rolldown_plugin_vite_manifest: handle duplicate chunk names for CSS entries (#9059) by @sapphi-red
- improve error message for invalid return values in function options (#9125) by @shulaoda
- await async export-star init wrappers (#9101) by @thezzisu
- never panic during diagnostic emission (#9091) by @IWANABETHATGUY
- include array rest pattern in binding_identifiers (#9112) by @IWANABETHATGUY
- rolldown: set worker thread count with ROLLDOWN_WORKER_THREADS (#9086) by @fpotter
- rolldown_plugin_lazy_compilation: escape request ID in proxy modules (#9102) by @h-a-n-a
- treat namespace member access as side-effect-free (#9099) by @IWANABETHATGUY
- relax overly conservative side-effect leak check in chunk optimizer (#9085) by @IWANABETHATGUY
- runtime: release `cb` reference after `__commonJS` factory initialization (#9067) by @hyf0-agent
- `@__NO_SIDE_EFFECTS__` wrapper should not remove dynamic imports (#9075) by @IWANABETHATGUY
- rolldown_plugin_vite_import_glob: use POSIX path join/normalize for glob resolution (#9077) by @shulaoda
- emit REQUIRE_TLA error when require() loads a module with top-level await (#9071) by @jaehafe
- emit namespace declaration for empty modules in manual chunks (#8993) by @privatenumber
- rolldown_plugin_vite_import_glob: keep common base on path segment boundary (#9070) by @shulaoda
- prevent circular runtime helper imports during facade elimination (#8989) (#9057) by @IWANABETHATGUY
- correct circular dependency check in facade elimination (#9047) by @h-a-n-a
- docs: correct dead link in CodeSplittingGroup.tags JSDoc (#9051) by @hyf0
- emit DUPLICATE_SHEBANG warning when banner contains shebang (#9026) by @IWANABETHATGUY

### 🚜 Refactor

- use semantic reference flags for member write detection (#9060) by @Dunqing
- extract UsedSymbolRefs newtype wrapper (#9130) by @IWANABETHATGUY
- dedupe await wrapping in export-star init emit (#9119) by @IWANABETHATGUY
- calculate side-effect-free function symbols on demand (#9120) by @IWANABETHATGUY
- extract duplicated top-level await handling into shared helper (#9087) by @IWANABETHATGUY
- rolldown_plugin_vite_import_glob: use split_first for get_common_base (#9069) by @shulaoda
- simplify ESM init deduplication with idiomatic insert check (#9044) by @IWANABETHATGUY

### 📚 Documentation

- document runtime module placement strategy in code-splitting design (#9062) by @IWANABETHATGUY
- clarify `options` hook behavior difference with Rollup in watch mode (#9053) by @sapphi-red
- meta/design: introduce module tags (#9017) by @hyf0

### ⚡ Performance

- convert `generate_transitive_esm_init` to iterative (#9046) by @IWANABETHATGUY

### 🧪 Testing

- merge strict/non_strict test variants using configVariants (#9089) by @IWANABETHATGUY

### ⚙️ Miscellaneous Tasks

- disable Renovate auto-updates for oxc packages (#9129) by @IWANABETHATGUY
- upgrade oxc@0.126.0 (#9127) by @Dunqing
- deps: update napi to v3.8.5 (#9126) by @renovate[bot]
- deps: update dependency @napi-rs/cli to v3.6.2 (#9123) by @renovate[bot]
- move lazy-compilation design doc (#9117) by @h-a-n-a
- deps: update dependency vite-plus to v0.1.18 (#9118) by @renovate[bot]
- deps: update dependency vite-plus to v0.1.17 (#9113) by @renovate[bot]
- deps: update oxc to v0.125.0 (#9094) by @renovate[bot]
- deps: update dependency follow-redirects to v1.16.0 [security] (#9103) by @renovate[bot]
- deps: update test262 submodule for tests (#9097) by @sapphi-red
- deps: update crate-ci/typos action to v1.45.1 (#9096) by @renovate[bot]
- deps: update rust crates (#9081) by @renovate[bot]
- deps: update npm packages (#9080) by @renovate[bot]
- remove outdated TODO in determine_module_exports_kind (#9072) by @jaehafe
- rust/test: support `extendedTests: false` shorthand in test config (#9050) by @hyf0
- ci: extract shared infra-changes anchor in path filters (#9054) by @hyf0
- add docs build check to catch dead links in PRs (#9052) by @hyf0

### ❤️ New Contributors

* @thezzisu made their first contribution in [#9101](#9101)
* @fpotter made their first contribution in [#9086](#9086)
* @jaehafe made their first contribution in [#9071](#9071)
* @privatenumber made their first contribution in [#8993](#8993)

Co-authored-by: shulaoda <165626830+shulaoda@users.noreply.github.com>

## Summary

Fixes a regression introduced by #9049: when the chunk optimizer merges
a shared module into an entry chunk, it can produce a static import
cycle between that entry chunk and a manual-split chunk that also
depends on the shared module.

## Problem

`would_create_circular_dependency` decides whether merging `source` (the
temp chunk holding shared modules) into `target` (an existing entry
chunk) is safe. The merge is unsafe iff, post-merge, `target` would
reach itself in the dependency graph.

#9049 split the algorithm into two cases based on whether `source` has
dependencies, in order to reduce false positives that were blocking
legitimate merges (the PR reported ~1,046 blocked merges and +12.5%
bundle size on a 2,200-entry application). However, the `source has
deps` branch only does a forward BFS from `source.deps` and drops the
post-merge alias step that the original algorithm used to model new
back-edges introduced by the merge:

```rust
// pre-#9049 step (removed in the source-has-deps branch)
if self.chunks[chunk_idx].dependencies.contains(&source_chunk_idx) {
  queue.push_back(target_chunk_idx);
}
```

Without that step, the BFS cannot see cycles where the closing edge is
one of the back-edges created by retargeting `source`'s importers onto
`target`.

## Concrete repro shape (issue #9225)

- `main.js` (entry) statically imports `api.js` and `env.js`, plus
dynamic imports `lazy.js`, `env-user.js`, `dep-user.js`.
- `api.js` is captured by a manual-split group `{ name: "api", test:
"api\\.js" }`.
- `api.js` statically imports `env.js`; `env-user.js` statically imports
`env.js`.
- `env.js` is a shared module not captured by any group
(`includeDependenciesRecursively: false`).

The optimizer selects `main` as the static dominator for `env.js`'s
consumers and merges `env.js` into it. After the merge:

- `api.js` and `env-user.js` rewrite their `./env.js` imports to
`./main.js`.
- `main.js` still statically imports `./api.js` (pre-existing edge).
- → static cycle `main.js ⇄ api.js` in the output.

In the `source has deps` branch, the BFS starts from `source.deps = {
dep.js's chunk }`. `dep.js` has no further deps and does not reach
`main`, so the BFS returns `false` and the merge proceeds. The dropped
alias step would have queued `target` when the BFS visited `api`'s chunk
(whose `dependencies` contain `source`), correctly detecting the cycle.

## Fix

Revert `would_create_circular_dependency` to the pre-#9049 unified
algorithm:

- BFS from `source.deps ∪ target.deps`.
- For each visited chunk `c`, when `source ∈ c.dependencies`, also
enqueue `target` (modeling the post-merge edge `c → target`).
- If `target` is dequeued, the merge would create a cycle.

This is sound: it catches both the forward path (`source.deps → target`)
and the back-edge path (`target → … → c → source-becomes-target`).

## Why reverting #9049 is safe: the `issues/9049` fixture is already
covered by #9085

The existing `crates/rolldown/tests/rolldown/issues/9049/` fixture
continues to pass after this revert, because **#9049's
`would_create_circular_dependency` change was never load-bearing for
that fixture**. Bisecting between rc.15 and rc.16 (rc.15 produces 4
chunks, rc.16 produces 3) pinpoints the actual fix as **#9085** — `fix:
relax overly conservative side-effect leak check in chunk optimizer`
(commit `5ff1a7265`). #9085 narrows the side-effect leak guard in
`try_insert_into_existing_chunk`: the merge is now blocked only when a
*different* user-defined entry can also reach the dynamic entries
depending on the common chunk, instead of unconditionally blocking on
any such dependency. That relaxation is what allows
`services/svc{0,1}.js` to merge into the `route0/route1` chunks for this
fixture.

The fixture's name (`issues/9049`) is therefore historically misleading:
it tests behavior fixed by #9085, not #9049. The false-positive
regressions #9049 was addressing in real-world bundles remain a concern
but are not exercised by any in-tree fixture; a follow-up can re-tighten
the check (e.g. by tracking dependent aliases more precisely) without
losing the regression coverage this PR adds.

## Regression test

`crates/rolldown/tests/rolldown/issues/9225/` reproduces the cycle that
#9049 was masking.

- `_config.json` sets up `manualCodeSplitting.groups = [{ name: "api",
test: "api\\.js" }]` with `includeDependenciesRecursively: false`.
- `_test.mjs` walks `dist/*.js`, parses the static-import edges, and
asserts the graph has no cycle. It additionally executes the bundled
entry, checks `globalThis.__rolldown_issue_7449_value === 300000`, and
verifies that the side-effect module `dep.js` runs exactly once even
when the dynamic chunks (which all transitively depend on `dep.js`)
load.

Without this fix, `_test.mjs` fails on the cycle assertion before any
runtime check runs.

## Testing

- `cargo test -p rolldown --test integration` — **1692 passed, 0 failed,
70 ignored**.
- `just test-node` (Rolldown vitest `test:main` + `test:watcher` +
Rollup compatibility suite) — **722 + 31 + 916 passed, 0 failed**.
- New `issues/9225` fixture passes both the cycle assertion and the
runtime checks.

Closes #9225.
`

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>