feat: LSP (Language Server Protocol) integration v3 — clean rebuild

[TheArchitectit]

Problem

All previous LSP PRs (#2813, #3016, #3098, #3099) were closed by the repo owner because they reverted upstream commits. The existing lsp_client.rs was a 747-line monolithic placeholder with no real language server communication -- the dispatch() method returned placeholder JSON instead of interacting with actual LSP servers.

Solution

Clean rebuild of the entire LSP integration layer from upstream/main, with zero upstream reverts. Replaced the placeholder with a fully functional, modular LSP subsystem split across four modules under 500 lines each.

Changes

New files

• rust/crates/runtime/src/lsp_client/ (mod.rs, types.rs, dispatch.rs, tests.rs, tests_lifecycle.rs)

  • LspRegistry with Arc<Mutex>-based thread-safe server tracking
  • Lazy-start: servers auto-start on first dispatch() or file notification
  • register_with_descriptor() for deferred process launch
  • Full dispatch() routing for 12 LSP actions: diagnostics, hover, definition, references, completion, symbols, format, code_action, rename, signature_help, code_lens, workspace_symbols
  • didOpen/didChange/didClose file notifications with diagnostic caching
  • 58 unit tests covering registration, dispatch, lifecycle, edge cases

• rust/crates/runtime/src/lsp_transport/ (mod.rs, tests.rs)

  • JSON-RPC 2.0 transport over stdin/stdout with Content-Length framing
  • TCP transport for GDScript/Godot LSP (port 6008) via socat/nc bridge
  • Request/response multiplexing with server-initiated notification queuing
  • Configurable request timeout (default 30s)
  • NODE_NO_WARNINGS=1 for Node.js-based servers
  • Graceful shutdown with kill fallback

• rust/crates/runtime/src/lsp_process/ (mod.rs, parse.rs, tests.rs)

  • Full LSP lifecycle: initialize -> initialized -> requests -> shutdown
  • Comprehensive client capabilities declaration
  • All LSP features: hover, goto_definition, references, completion, document_symbols, formatting, didOpen/didChange/didClose, code_action, rename, signature_help, code_lens, workspace_symbols
  • Response parsing for all LSP result types
  • Diagnostic draining from publishDiagnostics notifications

• rust/crates/runtime/src/lsp_discovery.rs

  • Auto-discovery of 14 known LSP servers via PATH probing
  • rustup proxy detection: falls back to rustup run stable rust-analyzer
  • Distro-aware install prompting (Debian, Fedora, Arch, openSUSE, Alpine, Void, NixOS, macOS, pip, npm)
  • GDScript/Godot TCP transport support

Modified files (LSP-only additions)

• rust/crates/runtime/src/config.rs -- LspServerConfig struct, lspAutoStart config field (default true), lsp per-language config parsing, lsp()/lsp_auto_start() accessors
• rust/crates/runtime/src/lib.rs -- pub mod lsp_discovery/lsp_process/lsp_transport declarations, LspServerConfig/LspServerDescriptor exports
• rust/crates/commands/src/lib.rs -- /lsp slash command (action, target args)
• rust/crates/tools/src/lib.rs -- LSP diagnostic enrichment in read/write/edit file operations, lsp_enrichment_for_path() and format_diagnostic_appendix() helpers, expanded LSP tool definition with code_action, rename, signature_help, code_lens, workspace_symbols actions
• rust/crates/rusty-claude-cli/src/main.rs -- SlashCommand::Lsp match arms

Diff verification

17 files changed, 4705 insertions(+), 759 deletions(-)

The 759 deletions are entirely from the old monolithic lsp_client.rs which was replaced by the properly modularized lsp_client/ directory. All modifications to existing files are LSP-only additions. No upstream code was reverted. All 5 critical commits (b64df99, 91a0681, c345ce6, 85e736c, 5b79413) are preserved.

Testing

1. cargo check --workspace -- compiles cleanly
2. cargo test -p runtime -- 610 tests pass (58 LSP-specific, including transport, process, discovery, client, and dispatch tests)
3. cargo test -p api -- 11 tests pass
4. All LSP tests cover: registration, file extension mapping, diagnostic management, dispatch routing, status display, action aliases, server lifecycle, descriptor-based registration, error handling for missing/disconnected servers

Related PRs

Supersedes #2813, #3016, #3098, #3099 (all closed due to upstream reverts)