# System map — microsoft/TypeScript

> Canonical page: https://codevetter.com/unpack/typescript/system-map

# System map — microsoft/TypeScript

Scanned commit 5f6db9c9148635b4cbf72f1193b821b9c6b42dcc (2026-09-22). Generated by codevetter codevetter 1.12.0 on 2026-09-22.

The system is one Go module (tsc/, module github.com/microsoft/TypeScript/tsc) in a go.work workspace with a tools/ module, orchestrated by a Node hereby build (Herebyfile.mjs). The single binary at tsc/cmd/tsc multiplexes three runtimes: batch compile via internal/execute, an LSP server via internal/lsp over stdin/stdout, and a programmatic API server via internal/api over stdio or a named pipe. The compiler core is layered scanner/parser/ast -> binder -> checker (parallel checker pool) -> transformers -> emitter/printer/sourcemap, all reading through a vfs.FS abstraction with lib .d.ts files embedded via internal/bundled. Shipping surfaces are the `tsc`/`tsgo` binary, per-platform npm packages wrapped by packages/typescript, and the packages/vscode-typescript VS Code extension.
- The only product entrypoint is tsc/cmd/tsc/main.go: runMain() applies a debug stack limit, routes `tsc --lsp` to runLSP and `tsc --api` to runAPI, and otherwise calls execute.CommandLine with the real OS system. — [tsc/cmd/tsc/main.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/cmd/tsc/main.go)
- The compiler core lives in tsc/internal packages layered as scanner -> parser -> ast -> binder -> checker, with module resolution in internal/module and emit in internal/transformers, internal/printer and internal/sourcemap. — [tsc/internal/parser/parser.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/parser/parser.go) [tsc/internal/binder/binder.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/binder/binder.go) [tsc/internal/checker/checker.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/checker/checker.go) [tsc/internal/compiler/program.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/compiler/program.go)
- compiler.NewProgram drives program construction: it calls processAllProgramFiles (the file loader/parse-task machinery in filesparser.go/fileloader.go), then initCheckerPool and verifyCompilerOptions. — [tsc/internal/compiler/program.go#L284-L294](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/compiler/program.go#L284-L294) [tsc/internal/compiler/filesparser.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/compiler/filesparser.go)
- All file IO goes through the vfs.FS interface (FileExists, ReadFile, WriteFile, GetAccessibleEntries, Realpath, ...); the CLI wraps the real OS FS with bundled.WrapFS so embedded lib.d.ts files are served from the binary. — [tsc/internal/vfs/vfs.go#L8-L43](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/vfs/vfs.go#L8-L43) [tsc/internal/bundled/bundled.go#L21-32](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/bundled/bundled.go#L21-L32) [tsc/cmd/tsc/sys.go#L124-138](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/cmd/tsc/sys.go#L124-L138)
- Build/test/lint/format/generate tasks are defined in Herebyfile.mjs; `npx hereby build` runs `go build ./cmd/tsc` into built/local/tsc and copies tsc/internal/bundled/libs into built/local. — [Herebyfile.mjs#L256-288](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/Herebyfile.mjs#L256-L288) [package.json](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/package.json)
- The repo is a Go workspace (go.work) containing modules tsc/ and tools/, requiring Go 1.27; the tsc module pins a small dependency set (go-winio, klauspost/compress, mackerelio/go-osstat, zeebo/xxh3, golang.org/x/*, gotest.tools). — [go.work](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/go.work) [tsc/go.mod](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/go.mod) [tools/go.mod](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tools/go.mod)
- The LSP server is internal/lsp.Server; its request dispatch is a lazily-built handlerMap (handlers()) mapping lsproto.Method values to registered handlers, with lsproto/lsp_generated.go generated from the upstream LSP meta-model. — [tsc/internal/lsp/server.go#L1224-1298](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/lsp/server.go#L1224-L1298) [tsc/internal/lsp/lsproto/lsp_generated.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/lsp/lsproto/lsp_generated.go) [Herebyfile.mjs#L558-567](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/Herebyfile.mjs#L558-L567)
- The programmatic API server (internal/api.StdioServer) accepts a connection over an ipc.Transport (stdio or named pipe/unix socket) and speaks either MessagePack (sync) or JSON-RPC (async) against a project.Session. — [tsc/internal/api/server.go#L62-120](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/api/server.go#L62-L120) [tsc/internal/ipc/conn.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/ipc/conn.go) [tsc/cmd/tsc/api.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/cmd/tsc/api.go)
- The npm package @typescript/typescript exposes a `tsc` bin that is a Node shim (bin/tsc -> lib/tsc.js) which resolves the platform-specific Go binary via lib/getExePath.js and execve/execFileSync's it. — [packages/typescript/package.json#L35-37](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/package.json#L35-L37) [packages/typescript/bin/tsc](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/bin/tsc) [packages/typescript/lib/tsc.js](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/lib/tsc.js) [packages/typescript/lib/getExePath.js](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/lib/getExePath.js)
- The VS Code extension 'native-preview' (display name 'TypeScript 7') activates on JS/TS languages and starts the Go server by spawning the resolved exe with args ['--lsp', ...pprofArgs] through vscode-languageclient. — [packages/vscode-typescript/package.json#L31-36](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/vscode-typescript/package.json#L31-L36) [packages/vscode-typescript/src/client.ts#L233-256](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/vscode-typescript/src/client.ts#L233-L256) [packages/vscode-typescript/src/extension.ts](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/vscode-typescript/src/extension.ts)
- internal/fswatch is a vendored, pure-Go (no cgo) filesystem watcher ported from @parcel/watcher, with per-OS backends including fanotify/inotify on Linux, FSEvents via hand-written arm64/amd64 assembly FFI on Darwin, and kqueue. — [tsc/internal/fswatch/README.md](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/fswatch/README.md) [tsc/internal/fswatch/fsevents_darwin_ffi_arm64.s](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/fswatch/fsevents_darwin_ffi_arm64.s) [tsc/internal/fswatch/inotify_linux.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/fswatch/inotify_linux.go)
- Release packaging is driven by hereby tasks (typescript:release, vscode-typescript:release) invoked from CI's release-build job and by Azure pipelines under tools/pipelines (typescript-build.yml, typescript-publish.yml, vscode-typescript-publish.yml). — [.github/workflows/ci.yml#L31-43](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/.github/workflows/ci.yml#L31-L43) [tools/pipelines/typescript-publish.yml](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tools/pipelines/typescript-publish.yml) [Herebyfile.mjs#L102-127](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/Herebyfile.mjs#L102-L127)
- tools/ holds a golangci-lint module plugin (customlint) registering repo-specific analyzers (bitclear, checkchildren, cleanup, emptycase, forbidparentaccess, shadow, unexportedapi), plus utilities like checkmodpaths and gen-proto. — [tools/customlint/plugin.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tools/customlint/plugin.go) [tools/cmd/checkmodpaths](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tools/cmd/checkmodpaths) [tools/gen-proto/main.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tools/gen-proto/main.go)

Every claim links to its cited files at the pinned commit. Citations identify source evidence; they do not establish runtime correctness. Independent CodeVetter scan — not reviewed by upstream maintainers.

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