Support multi-root Pydance workspaces

[ankitchouhan1020]

Summary

Pydance is a VS Code extension backed by the pylight LSP server. Its main feature is workspace-wide Python symbol search: VS Code sends workspace/symbol requests, and pylight answers from an in-memory index built at server startup and kept fresh by file watchers.

Before this change, Pydance only indexed the single legacy rootUri from LSP initialization. In a VS Code multi-root workspace like:

my-workspace.code-workspace
├── repo-a/
│   └── a.py
└── repo-b/
    └── b.py

only the top/root repo was indexed. Symbols from the other workspace folders were missing from Go to Symbol in Workspace / workspace/symbol results.

After this change, pylight reads InitializeParams.workspaceFolders and indexes every folder VS Code sends. It still falls back to rootUri for normal single-folder workspaces, so existing single-repo behavior stays unchanged.

Behavior changes

• Multi-root VS Code workspaces now index all workspace folders, not just the first/root folder.
• The file watcher subscribes to every workspace folder so edits in any repo update the index.
• Ignore rules remain per repo: each workspace folder gets its own IgnoreFilter, so each repo's .gitignore and default Python ignores apply relative to that repo.
• Bulk reindex rebuilds one shared symbol index from all workspace folders.
• Added Pydance: Restart Server so local testing can force a fresh LSP process and reindex without reloading the whole VS Code window.
• Bumped Pydance/Pylight to 0.3.1 for the local extension update.

Example

Given a workspace with two folders:

{
  "workspaceFolders": [
    { "uri": "file:///path/repo-a", "name": "repo-a" },
    { "uri": "file:///path/repo-b", "name": "repo-b" }
  ]
}

Pydance now:

1. indexes /path/repo-a
2. indexes /path/repo-b
3. watches both folders recursively
4. returns symbols from both repos for workspace/symbol

If VS Code only sends the legacy single-root shape:

{ "rootUri": "file:///path/repo-a" }

Pydance keeps the old behavior and indexes only /path/repo-a.

Extension test coverage

A new VS Code integration runner opens a real multi-root .code-workspace fixture while the existing single-root integration runner remains unchanged:

src/testWorkspaces/multi-root.code-workspace
├── ../testFixture/test.py
└── ../testFixtureSecond/second.py

That exercises the full headless VS Code path in CI:

• VS Code launches with a multi-root workspace file.
• The Pydance extension activates normally.
• The real pylight server indexes both workspace folders.
• vscode.executeWorkspaceSymbolProvider finds symbols from the second workspace folder.
• Pydance: Restart Server is executed and verified to reindex symbols after restart.

The test runner also uses a short /tmp user-data-dir to avoid macOS IPC socket path-length failures when the repo path is long.

Implementation notes

• LspServer now stores workspace_roots: Vec<PathBuf> instead of a single optional root.
• workspace_roots_from_initialize_params prefers workspaceFolders and falls back to rootUri.
• IndexUpdater::new_multi carries multiple roots and matching ignore filters.
• FileWatcher no longer owns a single-root ignore filter; it delegates watch decisions to the event handler, which has the multi-root context.
• Pydance: Restart Server stops the current LanguageClient, recreates it with the existing server/client options, reapplies trace config, and starts it again.

Test plan

• cd pylight && cargo test --quiet
• cd pydance && npm run compile
• cd pydance && npm run compile:tests
• cd pydance && npm run test:integration
• cd pydance && npm run test:integration:multi-root
• Installed locally into VS Code as toughtype.pydance-0.3.1
• Verified multi-root workspace indexing works locally
• Verified Pydance: Restart Server is available and restarts/reindexes locally

Not included

Dynamic workspace-folder add/remove handling after the LSP server has started is not included. Restarting the server covers that case for now; we can add workspace/didChangeWorkspaceFolders support if that becomes important.