This paper presents Sail-RISCV-WASM, which addresses three common limitations of existing browser-based RISC-V tools: fragmented capabilities, limited configurability, and disconnected build/debug pipelines. The system uses sail-riscv as its semantic baseline and compiles it to WebAssembly, forming a three-layer architecture in a pure browser environment: a Sail decode/execute layer, a toolchain layer (gas/ld/objdump), and a metadata layer based on the RISC-V UDB. Based on this architecture, the paper defines two core workflows. The first is configuration-sensitive online encode/decode with instruction metadata navigation for cross-configuration behavior comparison. The second is an in-browser assemble-to-ELF, execute, and interactive debugging loop, supporting instruction-level stepping, source-line stepping, synchronized source/disassembly views, and register/memory tracing. Results show that the system provides a complete single-page flow from exploration to build to diagnosis, with strong extension coverage and configuration flexibility.