# Feature catalog — microsoft/TypeScript

> Canonical page: https://codevetter.com/unpack/typescript/feature-catalog

# Feature catalog — microsoft/TypeScript

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

User-facing surface area splits into four groups. (1) The tsc CLI: single-project and build-mode compilation, watch mode, incremental/tsbuildinfo, --init/--showConfig/--listFilesOnly, tracing, pprof, diagnostics statistics. (2) A broad LSP feature set: pull diagnostics, hover, completions with auto-imports, definitions/references/implementations, rename, formatting, code actions, code lenses, inlay hints, semantic tokens, call hierarchy, workspace symbols, folding/selection/linked-editing, willRenameFiles, plus custom debugging and content-mapper methods. (3) A ~300-method programmatic API over IPC (parse, transpile, symbol/type queries, diagnostics, emit). (4) The VS Code extension's commands and settings. Notably, CHANGES.md documents deliberate feature removals versus the Strada compiler (Closure-style JSDoc features, constructor expandos, several removed options).
- `tsc` batch mode resolves a tsconfig.json via -p/--project or an ancestor-directory search (findConfigFile), supports --watch, --init (WriteConfigFile), --version, --help/--all, --showConfig, and rejects incompatible flag combos like --watch with --listFilesOnly. — [tsc/internal/execute/tsc.go#L122-267](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc.go#L122-L267) [tsc/internal/execute/tsc/help.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc/help.go) [tsc/internal/execute/tsc/init.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc/init.go)
- `tsc -b/--build` build mode parses a build command line (tsoptions.ParseBuildCommandLine) and runs build.NewOrchestrator over the project-reference graph. — [tsc/internal/execute/tsc.go#L53-120](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc.go#L53-L120) [tsc/internal/execute/build/orchestrator.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/build/orchestrator.go) [tsc/internal/tsoptions/parsedbuildcommandline.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/tsoptions/parsedbuildcommandline.go)
- Watch mode is created by createWatcher in internal/execute/watcher.go, layered on internal/execute/watchmanager and the vendored internal/fswatch backends. — [tsc/internal/execute/watcher.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/watcher.go) [tsc/internal/execute/watchmanager/watchmanager.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/watchmanager/watchmanager.go) [tsc/internal/fswatch/watcher_test.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/fswatch/watcher_test.go)
- Incremental compilation reads a prior .tsbuildinfo via incremental.ReadBuildInfoProgram, then wraps the new program with incremental.NewProgram to compute changes and reuse results; emit bookkeeping lives in emitfileshandler.go/snapshottobuildinfo.go. — [tsc/internal/execute/tsc.go#L287-343](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc.go#L287-L343) [tsc/internal/execute/incremental/program.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/incremental/program.go) [tsc/internal/execute/incremental/buildInfo.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/incremental/buildInfo.go)
- Diagnostics options --diagnostics/--extendedDiagnostics report phase timings and memory statistics (statistics.go), --generateTrace writes a trace file via internal/tracing, and --pprofDir starts CPU/heap profiling via internal/pprof. — [tsc/internal/execute/tsc/emit.go#L46-72](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc/emit.go#L46-L72) [tsc/internal/execute/tsc/statistics.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc/statistics.go) [tsc/internal/execute/tsc.go#L28-51](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc.go#L28-L51)
- The LSP server implements pull diagnostics (textDocument/diagnostic), hover, completion (+completionItem/resolve with auto-imports), definition/typeDefinition/sourceDefinition, references (incl. custom VS references), rename/prepareRename, workspace/willRenameFiles, formatting (document/range/on-type), codeAction, codeLens(+resolve), inlayHint, semanticTokens full/range, documentHighlight and a custom multiDocumentHighlight, foldingRange, selectionRange, linkedEditingRange, callHierarchy in/out, workspace/symbol, and VS autoInsert. — [tsc/internal/lsp/server.go#L1247-1297](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/lsp/server.go#L1247-L1297) [tsc/internal/ls/languageservice.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/ls/languageservice.go)
- Custom (non-standard) LSP methods are registered for logging ($/setLogVerbosity), developer profiling (runGC, saveHeapProfile, saveAllocProfile, startCPUProfile, stopCPUProfile), initializeAPISession, projectInfo, and setContentMapperContributions. — [tsc/internal/lsp/server.go#L1287-1297](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/lsp/server.go#L1287-L1297) [packages/vscode-typescript/package.json#L288-322](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/vscode-typescript/package.json#L288-L322)
- Automatic type acquisition (ATA) lives in internal/project/ata: it discovers typings (discovertypings.go, typesmap.go), validates package names, and installs npm packages through an injected ata.NpmExecutor implemented by the LSP server via exec `npm`. — [tsc/internal/project/ata/ata.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/project/ata/ata.go) [tsc/internal/project/ata/discovertypings.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/project/ata/discovertypings.go) [tsc/internal/project/ata/validatepackagename.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/project/ata/validatepackagename.go) [tsc/cmd/tsc/lsp.go#L59-63](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/cmd/tsc/lsp.go#L59-L63)
- Content mappers are a plugin mechanism: a tsconfig `contentMappers` entry names an npm package whose package.json declares Exec argv; the compiler spawns it as a child process speaking JSON-RPC (internal/ipc) to transform unsupported file types (e.g. .vue) into virtual TypeScript. — [tsc/internal/contentmapper/contentmapper.go#L1-52](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/contentmapper/contentmapper.go#L1-L52) [tsc/internal/contentmapper/hostimpl.go#L346-360](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/contentmapper/hostimpl.go#L346-L360) [tsc/internal/tsoptions/contentmappers.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/tsoptions/contentmappers.go)
- The IPC API exposes ~300 methods declared in internal/api/proto.go, including createSnapshot/updateSnapshot, createSourceFile, transpileModule/transpileDeclaration, parseConfigFile, getSymbolAtPosition, getTypeAtLocation, getSignaturesOfType, getSemanticDiagnostics/getSyntacticDiagnostics/etc., emit/emitToString, getJavaScriptEmit/getDeclarationEmit, intrinsic-type getters, and profiling controls. — [tsc/internal/api/proto.go#L57-140](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/api/proto.go#L57-L140) [tsc/internal/api/session.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/api/session.go)
- The npm package exposes the API under unstable exports: ./unstable/sync and ./unstable/async clients, ./unstable/fs (FS callbacks into the Go server), ./unstable/proto, and an AST toolkit (./unstable/ast with is/factory/scanner/visitor/clone subpaths). — [packages/typescript/package.json#L38-85](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/package.json#L38-L85) [packages/typescript/src/api/sync/client.ts](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/src/api/sync/client.ts) [packages/typescript/src/ast/ast.generated.ts](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/typescript/src/ast/ast.generated.ts)
- The VS Code extension contributes commands typescript.native-preview.{enable,disable,restart,output.focus,reportIssue,selectVersion,goToSourceDefinition,sortImports,removeUnusedImports,codeLens.showLocations} plus dev.* profiling commands, and settings like js/ts.trace.server, js/ts.server.pprofDir, js/ts.server.goMemLimit, js/ts.contentMappers.enabled. — [packages/vscode-typescript/package.json#L227-358](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/packages/vscode-typescript/package.json#L227-L358)
- A transpile-only path exists: internal/transpile provides transpileModule support and the API exposes transpileModule/transpileDeclaration methods; the hidden fmtMain path in execute can format a file using internal/format. — [tsc/internal/transpile/transpile.go](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/transpile/transpile.go) [tsc/internal/api/proto.go#L71-74](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/api/proto.go#L71-L74) [tsc/internal/execute/tsc.go#L66-89](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/internal/execute/tsc.go#L66-L89)
- tsc/CHANGES.md documents intentional behavior differences from the JS (Strada) compiler: trimmed JavaScript/JSDoc feature support (no Closure headers, no constructor expandos), removed options, and unified call-checking rules between .ts and .js. — [tsc/CHANGES.md](https://github.com/microsoft/TypeScript/blob/5f6db9c9148635b4cbf72f1193b821b9c6b42dcc/tsc/CHANGES.md)

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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