Add Astro Language Server Support

[dansasser]

Add Astro Language Server Support

Summary

This PR adds support for Astro framework files using the CompanionLanguageServer abstraction introduced in #829. The implementation follows the same dual-server architecture pattern used by Vue, where the domain-specific language server (Astro LS) handles .astro files while a companion TypeScript language server handles definitions, references, and rename operations for TypeScript/JavaScript code.

Motivation

Astro is a popular web framework for building content-focused websites. Like Vue, Astro components contain embedded TypeScript/JavaScript in their frontmatter section, requiring coordination between the Astro-specific language server and TypeScript tooling for full IDE functionality.

Architecture

Dual Language Server Design

                    AstroLanguageServer (extends CompanionLanguageServer)
                              |
         +--------------------+--------------------+
         |                                         |
    Astro LSP                              AstroTypeScriptServer
 (@astrojs/language-server)               (extends TypeScriptLanguageServer)
         |                                         |
    Handles:                               Handles:
    - .astro file parsing                  - Go-to-definition
    - Document symbols                     - Find references
    - Astro-specific features              - Rename operations
                                           - Cross-file resolution

Key Components

CompanionLanguageServer (from #829)

• Abstract base class for language servers requiring companion servers
• Manages companion lifecycle, LSP operation delegation, cross-file indexing
• Provides reference merging and deduplication

AstroLanguageServer

• Extends CompanionLanguageServer
• Uses @astrojs/language-server for Astro file handling
• Configures TypeScript companion for code intelligence operations

AstroTypeScriptServer

• Extends TypeScriptLanguageServer
• Configured with @astrojs/ts-plugin for Astro file understanding
• Opens .astro files with language ID "astro" for plugin recognition

EmbeddedLanguageConfig

• Configuration dataclass for embedded language handling
• Specifies which LSP operations each companion handles
• Defines file patterns for cross-file indexing

typescript_companion.py

• Shared helper for TypeScript companion configuration
• create_typescript_companion_config() - Standard TS config factory
• prefer_non_node_modules_definition() - Definition prioritization logic
• Reusable by Vue, Astro, and future Svelte implementations

Files Changed

New Files

File	Purpose
src/solidlsp/language_servers/astro_language_server.py	Main Astro LSP implementation (434 lines)
src/solidlsp/companion_ls.py	CompanionLanguageServer base class (390 lines, from #829)
src/solidlsp/embedded_language_config.py	Configuration dataclass for embedded languages (26 lines)
src/solidlsp/typescript_companion.py	Shared TypeScript companion helpers (57 lines)
test/solidlsp/astro/__init__.py	Test package marker
test/solidlsp/astro/test_astro_basic.py	Core functionality tests (141 lines)
test/solidlsp/astro/test_astro_symbol_retrieval.py	Symbol retrieval tests (78 lines)
test/resources/repos/astro/test_repo/	Complete Astro test project (10 files)

Modified Files

File	Changes
src/solidlsp/ls_config.py	Added ASTRO to Language enum, file matchers, LS class mapping
src/solidlsp/language_servers/vue_language_server.py	Refactored to use CompanionLanguageServer (net -162 lines)
src/solidlsp/language_servers/typescript_language_server.py	Added executable_path parameter for custom TS server locations
pyproject.toml	Added astro pytest marker
test/solidlsp/vue/test_vue_*.py	Added @pytest.mark.vue markers (4 files)
CHANGELOG.md	Added Astro, CompanionLanguageServer, and Vue refactor entries
README.md	Added Astro and Vue to supported languages list

Test Repository Structure

test/resources/repos/astro/test_repo/
├── astro.config.mjs          # Astro configuration
├── package.json              # NPM package definition
├── tsconfig.json             # TypeScript configuration
├── src/
│   ├── components/
│   │   ├── Header.astro      # Component with Props interface
│   │   └── Footer.astro      # Simple component
│   ├── layouts/
│   │   └── Layout.astro      # Layout with Props interface (tests frontmatter parsing)
│   ├── pages/
│   │   └── index.astro       # Page with imports and variable declarations
│   ├── stores/
│   │   └── counter.ts        # TypeScript store (tests cross-file resolution)
│   └── utils/
│       └── format.ts         # TypeScript utilities

Test Coverage

test_astro_basic.py

Test	What It Verifies
test_ls_is_running	Language server starts successfully
test_astro_document_symbols	Symbols extracted from .astro frontmatter (Props interface)
test_typescript_document_symbols	TypeScript file symbols accessible (CounterStore, createCounter)
test_find_definition_within_typescript	Go-to-definition within TypeScript files
test_find_references_within_typescript	Find references within TypeScript files
test_typescript_server_starts	Companion TypeScript server initialized
test_dual_server_definition_lookup	Definition lookup through companion server
test_astro_file_with_frontmatter	Handles frontmatter sections without errors
test_layout_astro_with_props_interface	Props interface found in Layout component

test_astro_symbol_retrieval.py

Test	What It Verifies
test_get_containing_symbol_in_typescript	Document symbols from .ts files within Astro project
test_find_references_to_typescript_export	References to TypeScript exports
test_go_to_definition_from_typescript	Definition resolution for TypeScript types
test_format_utils_symbols	Utility file symbols accessible (formatNumber, formatDate)

Runtime Dependencies

Automatically installed on first use:

• @astrojs/language-server@2.16.8 - Astro LSP
• typescript@5.9.3 - TypeScript SDK
• typescript-language-server@5.1.3 - TS LSP for companion server

Configurable via ls_specific_settings in serena_config.yml:

ls_specific_settings:
  astro:
    astro_language_server_version: "2.16.8"
  typescript:
    typescript_version: "5.9.3"
    typescript_language_server_version: "5.1.3"

Relationship to #829

This PR depends on the CompanionLanguageServer abstraction from #829:

• Uses the same companion server pattern as Vue
• Follows the same architecture for dual-LSP coordination
• Demonstrates the abstraction works for multiple frameworks

The base class handles:

• Companion server lifecycle management
• Cross-file domain file indexing
• Reference merging and deduplication
• LSP operation delegation

If #829 is merged first, this PR may need a rebase to resolve conflicts in shared files.

Breaking Changes

None. This is purely additive.

Checklist

• Language server implementation follows existing patterns
• Tests verify actual symbol names and references (not just non-null checks)
• Test repository includes meaningful source files for cross-file testing
• Added pytest marker for Astro tests
• Vue tests updated with markers (prevents unintended test collection)
• Runtime dependencies auto-install with version tracking
• Windows compatibility (.cmd suffix handling)
• CHANGELOG.md updated with detailed entries
• README.md updated with Astro and Vue in supported languages

CHANGELOG Entry

Already added to CHANGELOG.md:

* Language support:
  * **Add support for Astro** via @astrojs/language-server with companion TypeScript LS for code intelligence.
    Uses dual-server architecture where Astro LS handles `.astro` file parsing and document symbols,
    while a companion TypeScript server (configured with `@astrojs/ts-plugin`) handles go-to-definition,
    find references, and rename operations. Supports frontmatter TypeScript/JavaScript extraction,
    cross-file symbol resolution, and Props interface detection. Runtime dependencies auto-install on first use.
  * **Add `CompanionLanguageServer` abstraction** for language servers requiring companion servers (Vue, Astro, future Svelte).
    Manages companion lifecycle, LSP operation delegation with priority-based routing, cross-file domain file indexing
    with ref-count tracking, and reference merging/deduplication. Extracted shared TypeScript companion configuration
    to `typescript_companion.py` for reuse across framework implementations.
  * **Refactored Vue language server** to use `CompanionLanguageServer` base class, reducing code by ~160 lines
    while maintaining full functionality and improving maintainability.

---

Replaces #884 (closed) with proper CompanionLanguageServer-based implementation per maintainer guidance.

[MischaPanch]

@dansasser thank you for the PR. Just wanted to say that I haven't forgotten this, but since it's a fairly large change it will still take me some time to find time to review it properly. We just have many higher priority issues at the moment.

[dansasser]

@MischaPanch I understand completely. Thank you for taking the time to consider it. I love this project and use it everyday in my workflow. I'm more than happy to contribute to it or help maintain it in any way I can.