Compiler architecture

@wiz-sh/compiler keeps lexer, parser, immutable green tree/red navigation layer, semantic AST, binder, checker, target backends, emitter, and source maps in one package.

source → lossless tokens/tree → AST → scopes/symbols → checked project graph
       → target validation/lowering → shell writer → bundle/minify → output + source map

The lexer retains whitespace, comments, quote spelling, newlines, operators, and heredoc bodies. Parser recovery returns a source file even for incomplete quotes or functions, so the language service can continue answering. Stable entry points include parseSourceFile, createProgram, checkProgram, getDiagnostics, and emitProgram.

The target boundary is ShellTargetBackend. Bash, Zsh, and sh backends consume the same checked program without changing parser APIs. Bash and Zsh accept the supported Bash-shaped syntax. The sh backend validates its portable feature set first and reports WIZ5003 for arrays, associative arrays, [[ ... ]], process substitution, arithmetic commands, or namerefs instead of emitting behavior it cannot preserve.

.wiz, .sh, and .zsh roots can be fed through the pipeline. Translation between dialects is intentionally limited to the syntax the selected backend can preserve. The target controls the shebang, output suffix, declaration form, runtime assertions, and rewritten static source paths.

Bundling stays inside @wiz-sh/compiler because it consumes the checked source graph and lowered target output. The bundler replaces inert source markers after every dependency has been emitted, strips dependency shebangs, preserves execution order, and returns only graph entry points. Creating a separate package would duplicate module resolution and weaken compiler invariants.