dart_analysis_server_proxy

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A transparent LSP proxy between Dart-Code and the Dart analysis server. It lets dana, CLI tools and AI agents reuse the analyzer your IDE has already warmed up, instead of starting another one that costs minutes and gigabytes.

The IDE behaves exactly as before: every LSP message is forwarded unchanged. The proxy itself uses well under 100 MB and does not change the analyzer's memory. Dart-Code, the Dart SDK and the analysis server are not modified.

Supported platforms: macOS and Windows.

How it works

Dart-Code  <->  proxy  <->  Dart analysis server
                  ^
                  | authenticated loopback bridge
                 dana

After the IDE initializes, the proxy writes .dart_tool/dana-ide-bridge.json in each workspace root. dana finds it, connects with the token in it, and asks for diagnostics the IDE analyzer already holds.

Setup

dart pub global activate dart_analysis_server_proxy
dana_analysis_server analyzer-path --output <dir>/dana_analysis_server_proxy.dill

analyzer-path compiles the proxy with the current Dart SDK, writes it where you ask, and prints the setting to add. Put dart.analyzerPath in one of these places and restart the analyzer:

Scope	Setting goes in	Relative path starts from	Applies to
Single project	the project's .vscode/settings.json (can be committed)	the project folder	windows that open this project as a single folder; ignored in multi-root windows
Multi-project	the settings block of a .code-workspace file	the workspace file's directory	windows opened through that file, all of their folders
Global	user settings, absolute or ~/ path	—	every window

A project or workspace setting overrides the global one. Example for a workspace file next to the project folder:

// ~/work/app.code-workspace
{
  "folders": [{ "path": "app" }, { "path": "../shared_lib" }],
  "settings": {
    "dart.analyzerPath": "app/tool/dana/dana_analysis_server_proxy.dill"
  }
}

Things to know:

• The .dill file only loads on the Dart SDK that compiled it. Run analyzer-path again after changing the SDK. If the file is missing or cannot be loaded, Dart-Code reports an error and the analyzer does not start.
• A team can commit the .dill file (about 8 MB) with the project setting when everyone uses the same SDK, for example through FVM; regenerate it in the same change that bumps the SDK. For personal use, .dart_tool/dana/ is git-ignored but removed by flutter clean.
• To check it is active: the analyzer process runs your .dill with --lsp and .dart_tool/dana-ide-bridge.json exists. Without the proxy the process is dart language-server --protocol=lsp and there is no bridge file.
• To go back, remove the setting and restart the analyzer.

Using it with dana

# Require the IDE analyzer (exit 69 when no bridge is available).
dana check --root path/to/project --mode full --reuse-ide require
dana check --root path/to/project --files lib/main.dart --reuse-ide require

With the default --reuse-ide auto, dana uses the bridge when present and its own session otherwise.

• Results reflect the IDE's current state, unsaved edits included. Use --reuse-ide never when a gate must check only what is on disk.
• Right after the IDE starts or reloads, plugins may still be loading and publish nothing for a while, so a settled result can lack plugin lints. If you rely on plugin lints, keep a file that always yields one plugin diagnostic and retry while it is missing.

The bridge

• status, check for given files or folders, and fullCheck for the whole root, answered from the diagnostics the IDE analyzer has published; nothing is re-analyzed.
• fullCheck first tells the analyzer about Dart files changed since it was last idle, waits for the analysis pass, then waits until no diagnostics have arrived for 2 seconds, because plugins publish after the server goes idle. That last wait is capped (default 180 s, per request via settleLimitSeconds, 1–3600); reaching it answers settled: false.
• One endpoint per workspace root, each with its own token; results are limited to that root. The bridge listens on loopback only, cannot shut the analyzer down and never changes the IDE's unsaved content.

Environment variables

Variable	Default	Effect
DANA_PROXY_LOG	unset	also append proxy diagnostics (upstream start failures and exits, upstream stderr, LSP framing errors) to this file; they always go to stderr
DANA_ANALYSIS_TIMEOUT_SECONDS	1800	limit for upstream requests and fullCheck waits; 0 disables it
DANA_DART_EXECUTABLE	discovered	Dart runtime used to start the upstream analyzer when the proxy runs as a native executable; otherwise DART_SDK, FLUTTER_ROOT and PATH are tried

Commands

Run dana_analysis_server --help or dana_analysis_server help <command>. Arguments that are not one of its commands are forwarded to the analyzer unchanged; the proxy option --upstream-executable <dart> goes before --, for example dana_analysis_server --upstream-executable <dart> -- --lsp.

SDK changes and removal

After changing SDK, rerun analyzer-path with that SDK and restart the IDE analyzer.

To uninstall, remove dart.analyzerPath from the settings where it was configured and restart the analyzer, then run dart pub global deactivate dart_analysis_server_proxy.