Add flagship bindings with per-monomorphization generics - #1053
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logan-gatlin wants to merge 17 commits into
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Add flagship bindings with per-monomorphization generics#1053logan-gatlin wants to merge 17 commits into
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Adds first-class support for the Flagship feature-flag binding announced
on 2026-04-17. Users can now evaluate flags via `env.flagship("FLAGS")`
with a fluent `EvaluationContext` builder and typed `EvaluationDetails<T>`
responses.
- worker-sys: raw wasm_bindgen externs for all 9 Flagship JS methods
- worker: Flagship wrapper, EvaluationContext builder, EvaluationDetails<T>
- test: mini-flagship miniflare mock + 10 handlers + 16 vitest specs
- examples/flagship: runnable worker demoing value/details/context usage
need wasm-bindgen/wasm-bindgen#5180 for better ergonomics on generated bindings
inline closures were odd and didnt match the other examples
guybedford
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This is an excellent proof of concept proving real generics solves the issue we were having!
Let's integrate ts-gen generation into this PR, by adding support for generic-mono in ts-gen under an option, which when set outputs similar output to what you had here, but automatically.
- Enable experimental generic mono code generation - Update Flagship values and details to convert wrapper types
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Regenerated bindings using this branch of ts-gen: wasm-bindgen/ts-gen#31 |
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- Use native Rust primitives for Flagship values and evaluation details - Update examples and tests for generic string-compatible binding arguments
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| // not wasm-bindgen ABI types. `EvaluationContext` and `EnvBinding` also remain | ||
| // here because ts-gen does not synthesize them. |
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Why can't ts-gen synthesize EvaluationContext. isn't that what FlagshipEvaluationContext is?
It seems like we could support this in ts-gen if we had something along the lines of:
- first-class Record<K, V> lowering. Emit a #[wasm_bindgen(extends = Object)] newtype for the alias with new() plus setters derived from V — for a primitive union, per-variant set_string/set_number/set_bool (same machinery the dictionary builder already uses for fixed keys, just keyed by runtime &str). Then the generated methods take &FlagshipEvaluationContext and EvaluationContext in workers-rs is deleted. This is the direct fix for the "union erased to JsValue" warning too.
- keep getObjectValue in the .d.ts and let per-mono generics emit it as get_object_value<T: IntoWasmAbi + FromWasmAbi> / FlagshipEvaluationDetails. T is a JS-side type (Object/JsValue), so the serde layer becomes a one-line serde_wasm_bindgen::from_value at the call site or a tiny generic helper — not four hand-rolled externs and a parallel EvaluationDetails struct. One details type, not two.
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Amends the existing flagship work to use per-monomorphization generics. Eliminates the
into_value()conversions. Also addsimpl (De)Serializefor the types.Thanks to @connyay for doing most of the work on this