### 🚀 Features

- 616bfa2 minifier: Remove unreachable code after terminating statements
(#24441) (Dunqing)
- ddab89a data_structures: Add `likely` and `unlikely` functions
(#24368) (overlookmotel)
- a3a39f9 react_compiler: Implement enableEmitHookGuards codegen
(#24329) (Boshen)
- b79eef7 minifier: Apply De Morgan's law to negated comparison chains
in jump guards and loop tests (#24279) (Dunqing)
- 34ff7b4 minifier: Drop write-only property assignments to unused local
bindings by default (#24112) (Dunqing)
- 1b829d8 semantic: Record const enums in EnumData (#24268) (Dunqing)
- ba0944c semantic: Add `Scoping::set_symbol_span` (#24221) (camc314)

### 🐛 Bug Fixes

- 7d33363 minifier: Preserve guaranteed throws from class heritage
evaluation (#24349) (Dunqing)
- 058a62f semantic: Track ambient contexts in `SemanticBuilder` (#24327)
(camc314)
- 721eb0b transformer/decorator: Scope accessor class binding (#24330)
(camc314)
- 1ebdce3 semantic: Allow reserved keywords in ambient declaration types
(#24325) (camc314)
- 460176a track-memory-allocations: Exclude arena chunks from Sys allocs
(#24292) (Dunqing)
- af4922b transformer: Clear lowered namespace redeclarations (#24300)
(camc314)
- ffd2765 semantic: Mark declared computed `MethodDefinition`s as type
references (#24296) (camc314)
- f17514b isolated-declarations: Emit const readonly fields as types
(#24288) (camc314)
- 40f769d minifier: Make `__proto__` write tracking execution-order
independent (#24280) (Dunqing)
- 6371fed transformer: Remove stale enum member bindings (#24272)
(camc314)
- f05dfab transformer: Correct symbol flags for lowered namespaces
(#24271) (Dunqing)
- 84eeb55 transformer: Correct symbol flags for lowered enums (#24269)
(Dunqing)
- c3057da transformer: Preserve generated class binding spans (#24220)
(camc314)
- 8260096 transformer: Correct span for lowered namespace symbol
(#24222) (camc314)
- 42d00d3 semantic: Mark declared class heritage as type references
(#24237) (camc314)
- 588d997 semantic: Mark TS `PropertyDefinition`s computed fields as
type references (#24233) (camc314)
- 9b95632 semantic: Mark computed method keys in `TSMethodSignature`s as
type references (#24232) (camc314)

### ⚡ Performance

- 5b26643 transformer_plugins: Dispatch global defines by trailing name
(#23666) (Boshen)
- dce0f29 react_compiler: Replace all compiled functions in a single AST
walk (#24403) (Boshen)
- f85f0d8 ast: Delegate inherited enum variants in clone_in and estree
derives (#23555) (Boshen)
- 3ff0234 allocator: Remove `unwrap` from `ReplaceWith` (#24365)
(overlookmotel)
- ab22e80 transformer: Fix Rust 1.97 performance regression (#24354)
(camc314)
- b47585c parser: Use `ReplaceWith` instead of `TakeIn` (#24018)
(overlookmotel)
- b227a06 minifier: Use `ReplaceWith` instead of `TakeIn` (#24017)
(overlookmotel)

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

#24349 conservatively kept classes whose heritage resolved to a
class, lexical, or variable binding. That preserves errors excluded by
the minifier assumptions and leaves unused derived-class residue in
Rolldown chunks.

Treat resolved identifier heritage like other pure reads while retaining
the existing literal-arrow exception and heritage evaluation effects.
The runtime harness skips the six Test262 cases that exercise unsupported
TDZ violations or class-extension effects.

Implemented with AI assistance (Claude Code and OpenAI Codex). The
contributor remains responsible for reviewing, understanding, and
submitting the changes under the repository AI usage policy.

#24349 made unused-class removal conservatively keep every class whose heritage resolves to a class, lexical, or `var` binding. That preserves class-evaluation errors which the minifier assumptions explicitly allow optimizations to ignore, and it leaves `(class extends Base {});` residue in Rolldown chunks after tree-shaking ([rolldown#10274](rolldown/rolldown#10274)).

The minifier already documents both `No TDZ Violation` and `No side effects from extending a class`, and `oxc_ecmascript` explicitly ignores invalid-superclass errors so removable derived classes are not broadly deoptimized. Treat resolved identifier heritage like other pure reads while retaining the pre-existing literal-arrow exception, including its paren/sequence unwrap. Effects from evaluating the heritage expression, decorators, and effectful class elements remain observable.

The runtime harness already has minifier-only exclusions for unsupported inputs. Six Test262 fixtures covered by these assumptions are skipped only before the minifier variant, with the reason documented beside the list; codegen and transformer still execute, and `runtime.snap` remains unchanged.

## Example

Input:

```js
export var Base = class {};
export var Keep = class extends Base {};
var REMOVE = class extends Base {};
```

Before:

```js
var Base = class {}, Keep = class extends Base {};
(class extends Base {});
export { Base, Keep };
```

After:

```js
var Base = class {}, Keep = class extends Base {};
export { Base, Keep };
```

Verified with `cargo test -p oxc_minifier`, `cargo coverage runtime`, Clippy with warnings denied for `oxc_minifier` and `oxc_coverage`, `just minsize`, `just allocs`, formatting, and `just ready`. Minsize and `runtime.snap` are unchanged; the allocation snapshot records fewer allocations for `kitchen-sink.tsx`.

Implemented with AI assistance (Claude Code and OpenAI Codex). The contributor remains responsible for reviewing, understanding, and submitting the changes under the repository AI usage policy.