feat: add WASM web backend and weighted metering

Replace the previous cost middleware with a new meter implementation and add first-class WASM/web support. Removed src/cost.rs and introduced src/meter.rs which instruments WASM with fvm-wasm-instrument and a weighted opcode cost table; it exposes meter state and an instrument_wasm helper. Add web-specific runtime modules and shims (new run/web*.rs and src/web.rs) and adapt run.rs to support native and wasm targets. Cargo.toml: add a `web` feature, make wasm-bindgen/serde-wasm-bindgen/wasm-bindgen-futures optional, add fvm-wasm-instrument and target-specific deps for wasm32 and non-wasm builds; adjust wasmer features. README updated with browser build/wasm-bindgen usage and notes. Cargo.lock and tests updated to account for new/changed dependencies and behavior.

Author: JacobLinCool

Cargo.lock

@@ -26,6 +26,11 @@ crate-type = ["cdylib", "rlib"]
 
 [features]
 default = []
+web = [
+    "dep:wasm-bindgen",
+    "dep:serde-wasm-bindgen",
+    "dep:wasm-bindgen-futures",
+]
 cli = [
     "rocket",
     "reqwest",
@@ -40,19 +45,17 @@ cli = [
 ]
 
 [dependencies]
+anyhow = "1.0.100"
 serde = "1.0.228"
 serde_json = "1.0.149"
-tokio = { version = "1.49.0", default-features = false, features = [
-    "macros",
-    "rt",
-    "rt-multi-thread",
-] }
-wasmer = { version = "7.0.1", default-features = true }
-wasmer-wasix = { version = "0.700.1", default-features = true }
 wasmer-types = { version = "7.0.1" }
-sha256 = { version = "1.6.0" }
+fvm-wasm-instrument = "0.4.0"
+sha256 = { version = "1.6.0", default-features = false }
 tracing = { version = "0.1.44" }
 tracing-subscriber = { version = "0.3.22" }
+wasm-bindgen = { version = "0.2.100", optional = true }
+serde-wasm-bindgen = { version = "0.6.5", optional = true }
+wasm-bindgen-futures = { version = "0.4.50", optional = true }
 async-compression = { version = "0.4.40", features = [
     "tokio",
     "gzip",
@@ -78,6 +81,20 @@ reqwest-middleware-legacy = { package = "reqwest-middleware", version = "0.4.2",
 rocket = { version = "0.5.1", features = ["json"], optional = true }
 base64 = { version = "0.22.1", optional = true }
 
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+tokio = { version = "1.49.0", default-features = false, features = [
+    "macros",
+    "rt",
+    "rt-multi-thread",
+] }
+wasmer = { version = "7.0.1", default-features = false, features = ["sys-default"] }
+wasmer-wasix = { version = "0.700.1", default-features = false, features = ["sys-default"] }
+
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+js-sys = "0.3.77"
+wasmer = { version = "7.0.1", default-features = false, features = ["js-default"] }
+wasmer-wasix = { version = "0.700.1", default-features = false, features = ["js-default"] }
+
 [build-dependencies]
 vergen = { version = "9.1.0", features = [
     "build",

Cargo.toml

@@ -16,6 +16,45 @@ cargo install wark
 docker run --rm -p 33000:33000 jacoblincool/wark server
 ```
 
+## Web (WASI in Browser)
+
+WARK supports browser builds with the `web` feature on `wasm32`.
+
+Build the Rust library:
+
+```bash
+cargo build --target wasm32-unknown-unknown --features web --lib
+```
+
+Generate browser bindings:
+
+```bash
+cargo install -f wasm-bindgen-cli --version 0.2.113
+wasm-bindgen \
+  --target web \
+  --out-dir web/pkg \
+  target/wasm32-unknown-unknown/debug/wark.wasm
+```
+
+JavaScript usage:
+
+```javascript
+import { run_wasi } from "./web/pkg/wark.js";
+
+const response = run_wasi(new Uint8Array(wasmBytes), 1_000_000n, 64, "");
+console.log(response);
+```
+
+Web backend notes:
+
+- WASI execution works in browser builds.
+- Budget metering is unified across native and browser builds through wasm instrumentation.
+- Metering uses a weighted opcode table (for example `mul > add > local.get`).
+- Metering budget must be `<= 9,223,372,036,854,775,807` (`i64::MAX`).
+- Memory limit validation is enforced from observed linear-memory pages after execution.
+- `operations` currently returns an empty map.
+- For untrusted modules, execute `run_wasi` in a Web Worker to avoid freezing the UI thread.
+
 ## Configuration
 
 WARK now uses strict typed configuration loading at startup.
@@ -125,6 +164,7 @@ Request:
 ```bash
 cargo test --all-features --all-targets
 cargo test --no-default-features --all-targets
+cargo check --target wasm32-unknown-unknown --features web --lib
 ```
 
 The repository now includes unit, integration, and property tests across runtime, config, CLI, judger, and HTTP routes.
@@ -157,4 +197,5 @@ cargo clippy --all-features --all-targets -- -D warnings
 cargo test --all-features --all-targets
 cargo test --no-default-features --all-targets
 cargo bench --all-features -- --list
+cargo check --target wasm32-unknown-unknown --features web --lib
 ```