Flow Language for VS Code

Local editing support uses the shared flow-lsp server. Explicit check, run and test commands use the Flow CLI. An installed Flow on PATH needs no additional settings: the extension selects its sibling language server and the binaries discover their matching standard library and package catalog.

To select another complete installation, set flow.installationDirectory to its root (the directory containing bin, std and packages). Explicit flow.executable, flow.languageServerExecutable and flow.standardLibrary settings override that selection. The standard-library override names std/v1. These settings can be set in user settings or a trusted workspace. In a multi-root workspace, select the installation in the .code-workspace settings: one language server serves the window. Reload the extension after changing it. The Flow Language Server output channel reports the selected binaries. Explicit actions run the CLI's read-only installation diagnosis before dispatch and compare its identity with the initialized language server. A different version, installed revision or changed server path requires selecting one installation and reloading the window. Source builds without a recorded revision can be compared only by version; they do not establish exact source identity.

The extension requires Workspace Trust before activating or launching configured executables. Opening a trusted Flow file starts the language server; check, run and test remain explicit actions. flow.runsDirectory and flow.runArguments are user or remote settings, rather than workspace overrides.

The extension provides compiler diagnostics, hover, navigation, completion, references, rename, signature help, inlay hints, semantic highlighting and formatting. Inferred binding types and call parameter names appear inline when the editor's Editor: Inlay Hints setting is enabled. Use Flow: Check Saved File, Flow: Run Saved File or Flow: Test Saved File for explicit CLI actions. Run arguments are JSON text. Configure flow.runArguments for explicit Tool bindings or pauses. For a native Tool, follow the editor run setup, including the project profile's implementation consent. Test discovery is available in VS Code's Testing view. Explicit actions display the CLI's human output; the Testing view consumes structured results. The Output panel uses plain Unicode diagnostic layout rather than terminal color escapes.

Use Flow: Inspect Recorded Run, Flow: Show Recorded Facts or Flow: Replay Recorded Run to choose a recorded workspace run. The CLI selects its global history root by default; flow.runsDirectory explicitly selects another root. Each editor invocation receives an accepted-Start routing receipt before execution continues, so interrupted runs can be recovered without guessing which concurrent run belongs to it. Histories remain directly discoverable in the global root. The most recent 100 routing receipts persist across extension restarts. They retain paths, run IDs and a hash of the saved entry bytes before invocation; they contain no run values. Show Recorded Facts and Replay Recorded Run open readable CLI reports in editor tabs; the Flow Commands output panel reports source identity. Inspect Recorded Run retains its JSON inspection view. Values retain the CLI's exact numeric digits. These actions use the captured run directory and recorded source bundle, including after workspace sources or settings change or the entry file is deleted. The command output identifies current saved-entry differences and unsaved entry edits.

The adapter tests use target/debug/flow by default. Build it with cargo build -p flow-cli, or set FLOW_CLI explicitly to the binary being tested. The real editor packaging harness selects its separate build explicitly.

Build a local VSIX with npm run package in this directory. The shared Flow packager installs dependencies in a private project copy and prints the actual VSIX path in its JSON receipt. Use VS Code's Install from VSIX action with that artifact. For installed-host qualification, set FLOW_TOOLING_PACKAGE_RECEIPT to the generated editor-package.json, or set FLOW_TOOLING_TEST_VSIX to an explicit VSIX path, before npm run test:installed. Select the matching installation with flow.installationDirectory; the package includes the language client and syntax support.

These are non-normative usage instructions. Flow's specifications define the language and runtime behavior.