diff --git a/src/packs/lsp_server_metta/README.org b/src/packs/lsp_server_metta/README.org
new file mode 100644
index 00000000000..1a3c4ee53f3
--- /dev/null
+++ b/src/packs/lsp_server_metta/README.org
@@ -0,0 +1,114 @@
+* MeTTaLog Language server
+
+ **Currently a fork of prolog Language server. Will update this README later.**
+
+Still a work-in-progress -- please open an issue if you have any issues or feature requests!.
+
+Currently supports showing documentation on hover, go to definition, go to callers, listing defined symbols in the file, and showing a limited number of diagnostics.
+
+Only tested with SWI-Prolog, as it heavily uses its introspection facilities to do its stuff.
+It should work with any relatively-recent version of SWI-Prolog, but for best results (for "find references" in particular), use a version with ~xref_called/5~ (8.1.5 or newer; past commit [[https://github.com/SWI-Prolog/swipl-devel/commit/303f6430de5c9d7e225d8eb6fb8bb8b59e7c5f8f][303f6430de5c]]).
+
+Installable as a pack like ~?- pack_install(lsp_server).~
+
+* Emacs
+
+**  [[https://github.com/emacs-lsp/lsp-mode][lsp-mode]]:
+
+#+begin_src emacs-lisp
+(lsp-register-client
+  (make-lsp-client
+   :new-connection
+   (lsp-stdio-connection (list "swipl"
+                               "-g" "use_module(library(lsp_server))."
+                               "-g" "lsp_server:main"
+                               "-t" "halt"
+                               "--" "stdio"))
+   :major-modes '(prolog-mode)
+   :priority 1
+   :multi-root t
+   :server-id 'prolog-ls))
+#+end_src
+
+* Vim/Neovim
+
+**  [[https://github.com/autozimu/LanguageClient-neovim][LanguageClient]]:
+
+#+begin_src viml
+let g:LanguageClient_serverCommands = {
+\ 'prolog': ['swipl',
+\            '-g', 'use_module(library(lsp_server)).',
+\            '-g', 'lsp_server:main',
+\            '-t', 'halt',
+\            '--', 'stdio']
+\ }
+#+end_src
+
+* Neovim
+
+** [[https://github.com/neoclide/coc.nvim][CoC]]
+
+Put the following in ~coc-settings.json~ (which you can access by using the command ~:CocConfig~).
+
+#+begin_src json
+{"languageserver": {
+  "prolog-lsp": {
+    "command": "swipl",
+    "args": ["-g", "use_module(library(lsp_server)).",
+             "-g", "lsp_server:main",
+             "-t", "halt",
+             "--", "stdio"
+            ],
+    "filetypes": ["prolog"]
+  }}
+}
+#+end_src
+
+** Native LSP (for Neovim >= 0.5)
+
+Install the [[https://github.com/neovim/nvim-lspconfig][neovim/nvim-lspconfig]] package
+
+Put the following in ~$XDG_CONFIG_DIR/nvim/lua/lspconfig/prolog_lsp.lua~:
+
+#+begin_src lua
+local configs = require 'lspconfig/configs'
+local util = require 'lspconfig/util'
+
+configs.prolog_lsp = {
+  default_config = {
+    cmd = {"swipl",
+           "-g", "use_module(library(lsp_server)).",
+           "-g", "lsp_server:main",
+           "-t", "halt",
+           "--", "stdio"};
+    filetypes = {"prolog"};
+    root_dir = util.root_pattern("pack.pl");
+  };
+  docs = {
+     description = [[
+  https://github.com/jamesnvc/prolog_lsp
+
+  Prolog Language Server
+  ]];
+  }
+}
+-- vim:et ts=2 sw=2
+#+end_src
+
+Then add the following to ~init.vim~:
+
+#+begin_src viml
+lua << EOF
+require('lspconfig/prolog_lsp')
+require('lspconfig').prolog_lsp.setup{}
+EOF
+#+end_src
+
+* VSCode
+
+  - download the latest ~.vsix~ file from the [[https://github.com/jamesnvc/lsp_server/releases][releases page]]
+  - clone this repo and copy/symlink the ~vscode/~ directory to ~~/.vscode/extensions/~
+  - clone and build the ~.vsix~ file yourself by the follwing steps:
+    1. install ~vsce~ (~npm install -g vsce~)
+    2. run ~vsce publish~ from the ~vscode/~ directory
+    3. add the resulting ~.vsix~ to VSCode.
diff --git a/src/packs/lsp_server_metta/pack.pl b/src/packs/lsp_server_metta/pack.pl
new file mode 100644
index 00000000000..33c3c52bf5e
--- /dev/null
+++ b/src/packs/lsp_server_metta/pack.pl
@@ -0,0 +1,6 @@
+name(lsp_server_metta).
+title('A MeTTa LSP Server').
+version('0.0.2').
+author('Roy Ward', 'roy@orange-kiwi.com').
+home('https://github.com/trueagi-io/metta-wam').
+provides(lsp_server_metta).
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_changes.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_changes.pl
new file mode 100644
index 00000000000..940dc7e2fad
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_changes.pl
@@ -0,0 +1,76 @@
+:- module(lsp_metta_changes, [handle_doc_changes/2,
+                      doc_text_fallback/2,
+                       doc_text/2]).
+/** <module> LSP changes
+ Module for tracking edits to the source, in order to be able to act on
+ the code as it is in the editor buffer, before saving.
+
+ @author James Cash
+*/
+
+:- use_module(library(readutil), [read_file_to_codes/3]).
+
+:- dynamic doc_text/2.
+
+%! handle_doc_changes(+File:atom, +Changes:list) is det.
+%
+%  Track =Changes= to the file =File=.
+
+handle_doc_changes(_,_).
+
+handle_doc_changes(_, []) :- !.
+handle_doc_changes(Path, [Change|Changes]) :-
+    handle_doc_change(Path, Change),
+    handle_doc_changes(Path, Changes).
+
+handle_doc_change(Path, Change) :-
+    _{range: _{start: _{line: StartLine, character: StartChar},
+               end:   _{line: _EndLine0,   character: _EndChar}},
+      rangeLength: ReplaceLen, text: Text} :< Change,
+    !,
+    atom_codes(Text, ChangeCodes),
+    doc_text_fallback(Path, OrigCodes),
+    replace_codes(OrigCodes, StartLine, StartChar, ReplaceLen, ChangeCodes,
+                  NewText),
+    retractall(doc_text(Path, _)),
+    assertz(doc_text(Path, NewText)).
+handle_doc_change(Path, Change) :-
+    retractall(doc_text(Path, _)),
+    atom_codes(Change.text, TextCodes),
+    assertz(doc_text(Path, TextCodes)).
+
+%! doc_text_fallback(+Path:atom, -Text:text) is det.
+%
+%  Get the contents of the file at =Path=, either with the edits we've
+%  been tracking in memory, or from the file on disc if no edits have
+%  occured.
+doc_text_fallback(Path, Text) :-
+    doc_text(Path, Text), !.
+doc_text_fallback(Path, Text) :-
+    read_file_to_codes(Path, Text, []),
+    assertz(doc_text(Path, Text)).
+
+%! replace_codes(Text, StartLine, StartChar, ReplaceLen, ReplaceText, -NewText) is det.
+replace_codes(Text, StartLine, StartChar, ReplaceLen, ReplaceText, NewText) :-
+    phrase(replace(StartLine, StartChar, ReplaceLen, ReplaceText),
+           Text,
+           NewText).
+
+replace(0, 0, 0, NewText), NewText --> !, [].
+replace(0, 0, Skip, NewText) -->
+    !, skip(Skip),
+    replace(0, 0, 0, NewText).
+replace(0, Chars, Skip, NewText), Take -->
+    { length(Take, Chars) },
+    Take, !,
+    replace(0, 0, Skip, NewText).
+replace(Lines1, Chars, Skip, NewText), Line -->
+    line(Line), !,
+    { succ(Lines0, Lines1) },
+    replace(Lines0, Chars, Skip, NewText).
+
+skip(0) --> !, [].
+skip(N) --> [_], { succ(N0, N) }, skip(N0).
+
+line([0'\n]) --> [0'\n], !.
+line([C|Cs]) --> [C], line(Cs).
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_checking.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_checking.pl
new file mode 100644
index 00000000000..6f0e2d78303
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_checking.pl
@@ -0,0 +1,26 @@
+:- module(lsp_metta_checking, [check_errors/2]).
+/** <module> LSP Checking
+ Module for checking Prolog source files for errors and warnings.
+ @author Roy Ward
+*/
+% :- use_module(library(apply_macros)).
+% :- use_module(library(assoc), [list_to_assoc/2,
+%                                get_assoc/3]).
+% :- use_module(library(apply), [maplist/3]).
+% :- use_module(library(debug), [debug/3]).
+% :- use_module(library(lists), [member/2]).
+% :- use_module(library(prolog_xref), [xref_clean/1, xref_source/1]).
+% :- use_module(lsp_metta_utils, [clause_variable_positions/3]).
+%
+% :- dynamic message_hook/3.
+% :- multifile message_hook/3.
+%
+% %! check_errors(+Path:atom, -Errors:List) is det.
+% %
+% %  =Errors= is a list of the errors in the file given by =Path=.
+% %  This predicate changes the =user:message_hook/3= hook.
+
+% will do some real error checking later
+check_errors(_,[]).
+
+
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_colours.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_colours.pl
new file mode 100644
index 00000000000..ee0b2d726e6
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_colours.pl
@@ -0,0 +1,41 @@
+:- module(lsp_metta_colours, [
+                        token_types/1,
+                        token_modifiers/1]).
+
+% these are Prolog token types/modifiers. Need to change to meTTa.
+
+token_types([namespace,
+             type,
+             class,
+             enum,
+             interface,
+             struct,
+             typeParameter,
+             parameter,
+             variable,
+             property,
+             enumMember,
+             event,
+             function,
+             member,
+             macro,
+             keyword,
+             modifier,
+             comment,
+             string,
+             number,
+             regexp,
+             operator
+            ]).
+token_modifiers([declaration,
+                 definition,
+                 readonly,
+                 static,
+                 deprecated,
+                 abstract,
+                 async,
+                 modification,
+                 documentation,
+                 defaultLibrary
+                ]).
+
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_completion.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_completion.pl
new file mode 100644
index 00000000000..64b471cff8a
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_completion.pl
@@ -0,0 +1,68 @@
+% :- module(lsp_metta_completion, [completions_at/3]).
+% /** <module> LSP Completion
+%
+% This module implements code completion, based on defined predicates in
+% the file & imports.
+%
+% Uses =lsp_metta_changes= in order to see the state of the buffer being edited.
+%
+% @see lsp_metta_changes:doc_text_fallback/2
+%
+% @author James Cash
+% */
+%
+% :- use_module(library(apply), [maplist/3]).
+% :- use_module(library(lists), [numlist/3]).
+% :- use_module(library(prolog_xref), [xref_defined/3, xref_source/2]).
+% :- use_module(library(yall)).
+% :- use_module(lsp_metta_utils, [linechar_offset/3]).
+% :- use_module(lsp_metta_changes, [doc_text_fallback/2]).
+%
+% part_of_prefix(Code) :- code_type(Code, prolog_var_start).
+% part_of_prefix(Code) :- code_type(Code, prolog_atom_start).
+% part_of_prefix(Code) :- code_type(Code, prolog_identifier_continue).
+%
+% get_prefix_codes(Stream, Offset, Codes) :-
+%     get_prefix_codes(Stream, Offset, [], Codes).
+%
+% get_prefix_codes(Stream, Offset0, Codes0, Codes) :-
+%     peek_code(Stream, Code),
+%     part_of_prefix(Code), !,
+%     succ(Offset1, Offset0),
+%     seek(Stream, Offset1, bof, Offset),
+%     get_prefix_codes(Stream, Offset, [Code|Codes0], Codes).
+% get_prefix_codes(_, _, Codes, Codes).
+%
+% prefix_at(File, Position, Prefix) :-
+%     doc_text_fallback(File, DocCodes),
+%     setup_call_cleanup(
+%         open_string(DocCodes, Stream),
+%         ( linechar_offset(Stream, Position, _),
+%           seek(Stream, -1, current, Offset),
+%           get_prefix_codes(Stream, Offset, PrefixCodes),
+%           string_codes(Prefix, PrefixCodes) ),
+%         close(Stream)
+%     ).
+%
+% completions_at(File, Position, Completions) :-
+%     prefix_at(File, Position, Prefix),
+%     xref_source(File, [silent(true)]),
+%     findall(
+%         Result,
+%         ( xref_defined(File, Goal, _),
+%           functor(Goal, Name, Arity),
+%           atom_concat(Prefix, _, Name),
+%           args_str(Arity, Args),
+%           format(string(Func), "~w(~w)$0", [Name, Args]),
+%           format(string(Label), "~w/~w", [Name, Arity]),
+%           Result = _{label: Label,
+%                      insertText: Func,
+%                      insertTextFormat: 2}),
+%         Completions
+%     ).
+%
+% args_str(Arity, Str) :-
+%     numlist(1, Arity, Args),
+%     maplist([A, S]>>format(string(S), "${~w:_}", [A]),
+%            Args, ArgStrs),
+%     atomic_list_concat(ArgStrs, ', ', Str).
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_parser.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_parser.pl
new file mode 100644
index 00000000000..d921d313f6f
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_parser.pl
@@ -0,0 +1,35 @@
+:- module(lsp_metta_parser, [lsp_metta_request//1]).
+/** <module> LSP Parser
+
+Module for parsing the body & headers from an LSP client.
+
+@author James Cash
+*/
+
+:- use_module(library(assoc), [list_to_assoc/2, get_assoc/3]).
+:- use_module(library(codesio), [open_codes_stream/2]).
+:- use_module(library(dcg/basics), [string_without//2]).
+:- use_module(library(http/json), [json_read_dict/3]).
+
+header(Key-Value) -->
+    string_without(":", KeyC), ": ", string_without("\r", ValueC),
+    { string_codes(Key, KeyC), string_codes(Value, ValueC) }.
+
+headers([Header]) -->
+    header(Header), "\r\n\r\n", !.
+headers([Header|Headers]) -->
+    header(Header), "\r\n",
+    headers(Headers).
+
+json_chars(0, []) --> [].
+json_chars(N, [C|Cs]) --> [C], { succ(Nn, N) }, json_chars(Nn, Cs).
+
+lsp_metta_request(_{headers: Headers, body: Body}) -->
+    headers(HeadersList),
+    { list_to_assoc(HeadersList, Headers),
+      get_assoc("Content-Length", Headers, LengthS),
+      number_string(Length, LengthS) },
+    json_chars(Length, JsonCodes),
+    { ground(JsonCodes),
+      open_codes_stream(JsonCodes, JsonStream),
+      json_read_dict(JsonStream, Body, []) }.
diff --git a/src/packs/lsp_server_metta/prolog/lsp_metta_utils.pl b/src/packs/lsp_server_metta/prolog/lsp_metta_utils.pl
new file mode 100644
index 00000000000..748dd950d8d
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_metta_utils.pl
@@ -0,0 +1,28 @@
+:- module(lsp_metta_utils, [
+%                       called_at/4,
+%                       defined_at/3,
+%                       name_callable/2,
+%                       relative_ref_location/4,
+%                       clause_variable_positions/3,
+%                       seek_to_line/2,
+%                       linechar_offset/3,
+%                       clause_in_file_at_position/3,
+                        help_at_position/4
+                        ]).
+% /** <module> LSP Utils
+%
+% Module with a bunch of helper predicates for looking through prolog
+% source and stuff.
+%
+% @author James Cash
+% */
+%! help_at_position(+Path:atom, +Line:integer, +Char:integer, -Help:string) is det.
+%
+%  =Help= is the documentation for the term under the cursor at line
+%  =Line=, character =Char= in the file =Path=.
+
+help_at_position(_Path, _Line1, _Char0, "blah blah blah") :- !. % clause_in_file_at_position(Clause, Path, line_char(Line1, Char0)), !.
+% help_at_position(Path, Line1, Char0, S) :-
+%     clause_in_file_at_position(Clause, Path, line_char(Line1, Char0)),
+%     predicate_help(Path, Clause, S0),
+%     format_help(S0, S).
diff --git a/src/packs/lsp_server_metta/prolog/lsp_server_metta.pl b/src/packs/lsp_server_metta/prolog/lsp_server_metta.pl
new file mode 100644
index 00000000000..079fa368a3a
--- /dev/null
+++ b/src/packs/lsp_server_metta/prolog/lsp_server_metta.pl
@@ -0,0 +1,316 @@
+:- module(lsp_server_metta, [main/0]).
+/** <module> LSP Server
+
+The main entry point for the Language Server implementation.
+
+@author James Cash
+*/
+
+:- use_module(library(apply), [maplist/2]).
+:- use_module(library(debug), [debug/3, debug/1]).
+:- use_module(library(http/json), [atom_json_dict/3]).
+:- use_module(library(prolog_xref)).
+:- use_module(library(prolog_source), [directory_source_files/3]).
+:- use_module(library(utf8), [utf8_codes//1]).
+:- use_module(library(yall)).
+
+:- use_module(lsp_metta_utils).
+:- use_module(lsp_metta_checking, [check_errors/2]).
+:- use_module(lsp_metta_parser, [lsp_metta_request//1]).
+:- use_module(lsp_metta_changes, [handle_doc_changes/2]).
+:- use_module(lsp_metta_completion, [completions_at/3]).
+:- use_module(lsp_metta_colours, [
+%                            file_colours/2,
+%                            file_range_colours/4,
+                            token_types/1,
+                            token_modifiers/1]).
+
+main :-
+    set_prolog_flag(debug_on_error, false),
+    set_prolog_flag(report_error, true),
+    set_prolog_flag(toplevel_prompt, ''),
+    current_prolog_flag(argv, Args),
+    debug(server),
+    debug(server(high)),
+    start(Args).
+
+start([stdio]) :- !,
+    debug(server, "Starting stdio client", []),
+    stdio_server.
+start(Args) :-
+    debug(server, "Unknown args ~w", [Args]).
+
+% stdio server
+
+stdio_server :-
+    current_input(In),
+    set_stream(In, buffer(full)),
+    set_stream(In, newline(posix)),
+    set_stream(In, tty(false)),
+    set_stream(In, representation_errors(error)),
+    % handling UTF decoding in JSON parsing, but doing the auto-translation
+    % causes Content-Length to be incorrect
+    set_stream(In, encoding(octet)),
+    current_output(Out),
+    set_stream(Out, encoding(utf8)),
+    stdio_handler(A-A, In).
+
+% [TODO] add multithreading? Guess that will also need a message queue
+% to write to stdout
+stdio_handler(Extra-ExtraTail, In) :-
+    wait_for_input([In], _, infinite),
+    fill_buffer(In),
+    read_pending_codes(In, ReadCodes, Tail),
+    ( Tail == []
+    -> true
+    ; ( current_output(Out),
+        ExtraTail = ReadCodes,
+        handle_requests(Out, Extra, Remainder),
+        stdio_handler(Remainder-Tail, In) )
+    ).
+
+handle_requests(Out, In, Tail) :-
+    handle_request(Out, In, Rest), !,
+    ( var(Rest)
+    -> Tail = Rest
+    ; handle_requests(Out, Rest, Tail) ).
+handle_requests(_, T, T).
+
+% general handling stuff
+
+send_message(Stream, Msg) :-
+    put_dict(jsonrpc, Msg, "2.0", VersionedMsg),
+    atom_json_dict(JsonCodes, VersionedMsg, [as(codes), width(0)]),
+    phrase(utf8_codes(JsonCodes), UTF8Codes),
+    length(UTF8Codes, ContentLength),
+    format(Stream, "Content-Length: ~w\r\n\r\n~s", [ContentLength, JsonCodes]),
+    flush_output(Stream).
+
+handle_request(OutStream, Input, Rest) :-
+    phrase(lsp_metta_request(Req), Input, Rest),
+    debug(server(high), "Request ~w", [Req.body]),
+    catch(
+        ( handle_msg(Req.body.method, Req.body, Resp),
+          debug(server(high), "response ~w", [Resp]),
+          ( is_dict(Resp) -> send_message(OutStream, Resp) ; true ) ),
+        Err,
+        ( debug(server, "error handling msg ~w", [Err]),
+          get_dict(id, Req.body, Id),
+          send_message(OutStream, _{id: Id,
+                                    error: _{code: -32001,
+                                             message: "server error"}})
+        )).
+
+% Handling messages
+
+server_capabilities(
+    _{textDocumentSync: _{openClose: true,
+                          change: 2, %incremental
+                          save: _{includeText: false},
+                          willSave: false,
+                          willSaveWaitUntil: false %???
+                          },
+      hoverProvider: true,
+      completionProvider: _{},
+      definitionProvider: true,
+      declarationProvider: true,
+      implementationProvider: true,
+      referencesProvider: true,
+      documentHighlightProvider: false,
+      documentSymbolProvider: true,
+      workspaceSymbolProvider: true,
+      codeActionProvider: false,
+      %% codeLensProvider: false,
+      documentFormattingProvider:false,
+      %% documentOnTypeFormattingProvider: false,
+      renameProvider: false,
+      % documentLinkProvider: false,
+      % colorProvider: true,
+      foldingRangeProvider: false,
+      executeCommandProvider: _{commands: ["query", "assert"]},
+      semanticTokensProvider: _{legend: _{tokenTypes: TokenTypes,
+                                          tokenModifiers: TokenModifiers},
+                                range: true,
+                                % [TODO] implement deltas
+                                full: _{delta: false}},
+      workspace: _{workspaceFolders: _{supported: true,
+                                       changeNotifications: true}}
+     }
+) :-
+    token_types(TokenTypes),
+    token_modifiers(TokenModifiers).
+
+:- dynamic loaded_source/1.
+
+% messages (with a response)
+handle_msg("initialize", Msg,
+           _{id: Id, result: _{capabilities: ServerCapabilities} }) :-
+    _{id: Id, params: Params} :< Msg, !,
+    ( Params.rootUri \== null
+    -> ( atom_concat('file://', RootPath, Params.rootUri),
+         directory_source_files(RootPath, Files, [recursive(true)]),
+         maplist([F]>>assert(loaded_source(F)), Files) )
+    ; true ),
+    server_capabilities(ServerCapabilities).
+handle_msg("shutdown", Msg, _{id: Id, result: null}) :-
+    _{id: Id} :< Msg,
+    debug(server, "recieved shutdown message", []).
+
+% CALL: textDocument/hover
+% IN: params:{position:{character:11,line:56},textDocument:{uri:file://<FILEPATH>}}}
+% OUT: {id:21,result:{contents:{kind:plaintext,value:<ALL_THE_STUFF>}}}
+handle_msg("textDocument/hover", Msg, _{id: Id, result: Response}) :-
+    _{params: _{position: _{character: Char0, line: Line0},
+                textDocument: _{uri: Doc}}, id: Id} :< Msg,
+    atom_concat('file://', Path, Doc),
+    Line1 is Line0 + 1,
+    (  help_at_position(Path, Line1, Char0, Help)
+    -> Response = _{contents: _{kind: plaintext, value: Help}}
+    ;  Response = null).
+
+% CALL: textDocument/documentSymbol
+% IN: params:{textDocument:{uri:file://<FILEPATH>}}
+% OUT: {id:1,result:[
+%    {kind:12,location:{range:{end:{character:0,line:37},start:{character:1,line:35}},uri:file://<FILEPATH>},name:called_at/4},
+%    {kind:12,location:{range:{end:{character:0,line:66},start:{character:1,line:64}},uri:file://<FILEPATH>},},name:defined_at/3} ... ]}
+handle_msg("textDocument/documentSymbol", Msg, _{id: Id, result: []}) :-
+     _{id: Id, params: _{textDocument: _{uri: Doc}}} :< Msg.
+% handle_msg("textDocument/documentSymbol", Msg, _{id: Id, result: Symbols}) :-
+%     _{id: Id, params: _{textDocument: _{uri: Doc}}} :< Msg,
+%     atom_concat('file://', Path, Doc), !,
+%     xref_source(Path),
+%     findall(
+%         Symbol,
+%         ( xref_defined(Path, Goal, local(Line)),
+%           succ(Line, NextLine),
+%           succ(Line0, Line),
+%           functor(Goal, Name, Arity),
+%           format(string(GoalName), "~w/~w", [Name, Arity]),
+%           Symbol = _{name: GoalName,
+%                      kind: 12, % function
+%                      location:
+%                      _{uri: Doc,
+%                        range: _{start: _{line: Line0, character: 1},
+%                                 end: _{line: NextLine, character: 0}}}}
+%         ),
+%         Symbols).
+
+% CALL: method:textDocument/definition
+% IN: params:{position:{character:55,line:174},textDocument:{uri:file://<FILE_PATH>}}}
+% OUT: {id:42,result:null} % need to find a better example
+% handle_msg("textDocument/definition", Msg, _{id: Id, result: Location}) :-
+%     _{id: Id, params: Params} :< Msg,
+%     _{textDocument: _{uri: Doc},
+%       position: _{line: Line0, character: Char0}} :< Params,
+%     atom_concat('file://', Path, Doc),
+%     succ(Line0, Line1),
+%     clause_in_file_at_position(Name/Arity, Path, line_char(Line1, Char0)),
+%     defined_at(Path, Name/Arity, Location).
+% handle_msg("textDocument/definition", Msg, _{id: Msg.id, result: null}) :- !.
+
+% handle_msg("textDocument/references", Msg, _{id: Id, result: Locations}) :-
+%     _{id: Id, params: Params} :< Msg,
+%     _{textDocument: _{uri: Uri},
+%       position: _{line: Line0, character: Char0}} :< Params,
+%     atom_concat('file://', Path, Uri),
+%     succ(Line0, Line1),
+%     clause_in_file_at_position(Clause, Path, line_char(Line1, Char0)),
+%     findall(
+%         Location,
+%         ( loaded_source(Doc),
+%           atom_concat('file://', Doc, DocUri),
+%           called_at(Doc, Clause, Caller, Loc),
+%           relative_ref_location(DocUri, Caller, Loc, Location)
+%         ),
+%         Locations), !.
+% handle_msg("textDocument/references", Msg, _{id: Msg.id, result: null}) :- !.
+
+% handle_msg("textDocument/completion", Msg, _{id: Id, result: Completions}) :-
+%     _{id: Id, params: Params} :< Msg,
+%     _{textDocument: _{uri: Uri},
+%       position: _{line: Line0, character: Char0}} :< Params,
+%     atom_concat('file://', Path, Uri),
+%     succ(Line0, Line1),
+%     completions_at(Path, line_char(Line1, Char0), Completions).
+
+handle_msg("textDocument/semanticTokens", Msg, Response) :-
+    handle_msg("textDocument/semanticTokens/full", Msg, Response).
+% handle_msg("textDocument/semanticTokens/full", Msg,
+%            _{id: Id, result: _{data: Highlights}}) :-
+%     _{id: Id, params: Params} :< Msg,
+%     _{textDocument: _{uri: Uri}} :< Params,
+%     atom_concat('file://', Path, Uri), !,
+%     xref_source(Path),
+%     file_colours(Path, Highlights).
+
+% handle_msg("textDocument/semanticTokens/range", Msg,
+%            _{id: Id, result: _{data: Highlights}}) :-
+%     _{id: Id, params: Params} :< Msg,
+%     _{textDocument: _{uri: Uri}, range: Range} :< Params,
+%     _{start: _{line: StartLine0, character: StartChar},
+%       end: _{line: EndLine0, character: EndChar}} :< Range,
+%     atom_concat('file://', Path, Uri), !,
+%     succ(StartLine0, StartLine), succ(EndLine0, EndLine),
+%     xref_source(Path),
+%     file_range_colours(Path,
+%                        line_char(StartLine, StartChar),
+%                        line_char(EndLine, EndChar),
+%                        Highlights).
+
+% notifications (no response)
+
+% CALL: textDocument/didOpen
+% IN: params:{textDocument:{languageId:prolog,text:<FILE_CONTENTS>,uri:file://<FILEPATH>,version:1}}
+% OUT: {method:textDocument/publishDiagnostics,params:{diagnostics:[
+%    {message:Singleton variable Offset,range:{end:{character:21,line:319},start:{character:15,line:319}},severity:2,source:prolog_xref},
+%    {message:Singleton variable SubPos,range:{end:{character:29,line:319},start:{character:23,line:319}},severity:2,source:prolog_xref} ... ]
+%   ,uri:file://<FILEPATH>}}
+handle_msg("textDocument/didOpen", Msg, Resp) :-
+    _{params: _{textDocument: TextDoc}} :< Msg,
+    _{uri: FileUri} :< TextDoc,
+    atom_concat('file://', Path, FileUri),
+    ( loaded_source(Path) ; assertz(loaded_source(Path)) ),
+    check_errors_resp(FileUri, Resp).
+
+handle_msg("textDocument/didChange", Msg, false) :-
+    _{params: _{textDocument: TextDoc,
+                contentChanges: Changes}} :< Msg,
+    _{uri: Uri} :< TextDoc,
+    atom_concat('file://', Path, Uri),
+    handle_doc_changes(Path, Changes).
+
+handle_msg("textDocument/didSave", Msg, Resp) :-
+    _{params: Params} :< Msg,
+    check_errors_resp(Params.textDocument.uri, Resp).
+
+handle_msg("textDocument/didClose", Msg, false) :-
+    _{params: _{textDocument: TextDoc}} :< Msg,
+    _{uri: FileUri} :< TextDoc,
+    atom_concat('file://', Path, FileUri),
+    retractall(loaded_source(Path)).
+
+handle_msg("initialized", Msg, false) :-
+    debug(server, "initialized ~w", [Msg]).
+
+handle_msg("$/setTrace", _Msg, false).
+
+handle_msg("$/cancelRequest", Msg, false) :-
+    debug(server, "Cancel request Msg ~w", [Msg]).
+
+handle_msg("exit", _Msg, false) :-
+    debug(server, "recieved exit, shutting down", []),
+    halt.
+
+% wildcard
+handle_msg(_, Msg, _{id: Id, error: _{code: -32603, message: "Unimplemented"}}) :-
+    _{id: Id} :< Msg, !,
+    debug(server, "unknown message ~w", [Msg]).
+handle_msg(_, Msg, false) :-
+    debug(server, "unknown notification ~w", [Msg]).
+
+check_errors_resp(FileUri, _{method: "textDocument/publishDiagnostics",
+                             params: _{uri: FileUri, diagnostics: Errors}}) :-
+    atom_concat('file://', Path, FileUri),
+    check_errors(Path, Errors).
+check_errors_resp(_, false) :-
+    debug(server, "Failed checking errors", []).
diff --git a/src/packs/lsp_server_metta/vscode/README.md b/src/packs/lsp_server_metta/vscode/README.md
new file mode 100644
index 00000000000..e6ca5c8c6ec
--- /dev/null
+++ b/src/packs/lsp_server_metta/vscode/README.md
@@ -0,0 +1,3 @@
+# MeTTa LSP
+
+VSCode client for MeTTa LSP server
diff --git a/src/packs/lsp_server_metta/vscode/extension.js b/src/packs/lsp_server_metta/vscode/extension.js
new file mode 100644
index 00000000000..677e22dc3f2
--- /dev/null
+++ b/src/packs/lsp_server_metta/vscode/extension.js
@@ -0,0 +1,42 @@
+const vscode = require('vscode');
+const lsp = require('vscode-languageclient');
+
+function activate(context) {
+
+  let serverOptions = {
+    run: {command: "swipl",
+          args: ["-g", "use_module(library(lsp_server_metta)).",
+                 "-g", "lsp_server_metta:main",
+                 "-t", "halt",
+                 "--", "stdio"]},
+    debug: {command: "swipl",
+            args: ["-g", "use_module(library(syslog)).",
+                   "-g", "openlog(metta_lsp, [], user).",
+                   "-g", "use_module(library(debug)).",
+                   "-g", "debug(server(high)).",
+                   "-g", "use_module(library(lsp_server_metta)).",
+                   "-g", "lsp_server_metta:main",
+                   "-t", "halt",
+                   "--", "stdio"]}
+  };
+
+  let clientOptions = {
+    documentSelector: [{scheme: "file", language: "metta"}],
+  };
+
+  let client = new lsp.LanguageClient(
+    'metta-lsp',
+    'MeTTa Language Client',
+    serverOptions,
+    clientOptions
+  );
+
+  context.subscriptions.push(client.start());
+}
+exports.activate = activate;
+
+function deactivate(context) {
+  if (!context.client) { return; }
+  context.client.stop();
+}
+exports.deactivate = deactivate;
diff --git a/src/packs/lsp_server_metta/vscode/metta.config.json b/src/packs/lsp_server_metta/vscode/metta.config.json
new file mode 100644
index 00000000000..288c272d8a3
--- /dev/null
+++ b/src/packs/lsp_server_metta/vscode/metta.config.json
@@ -0,0 +1,24 @@
+{
+  "comments": {
+    "lineComment": ";"
+  },
+  "brackets": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"]
+  ],
+  "autoClosingPairs": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"],
+    ["\"", "\""],
+    ["'", "'"]
+  ],
+  "surroundingPairs": [
+    ["{", "}"],
+    ["[", "]"],
+    ["(", ")"],
+    ["\"", "\""],
+    ["'", "'"]
+  ]
+}
diff --git a/src/packs/lsp_server_metta/vscode/package.json b/src/packs/lsp_server_metta/vscode/package.json
new file mode 100644
index 00000000000..d05940ed0fd
--- /dev/null
+++ b/src/packs/lsp_server_metta/vscode/package.json
@@ -0,0 +1,51 @@
+{
+  "name": "metta-lsp",
+  "displayName": "metta-lsp",
+  "description": "A language server for MeTTa",
+  "author": "Roy Ward",
+  "license": "LGPL-3.0",
+  "publisher": "RoyWard",
+  "version": "0.0.2",
+  "categories": [
+    "Other"
+  ],
+  "keywords": [
+    "mettalog"
+  ],
+  "engines": {
+    "vscode": "^1.54.0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/royward/lsp_server_metta"
+  },
+  "activationEvents": [
+    "onLanguage:metta"
+  ],
+  "main": "./extension",
+  "contributes": {
+    "languages": [
+      {
+        "id": "metta",
+        "aliases": [
+          "metta",
+          "mettalog",
+          "MeTTa",
+          "MeTTaLog",
+          "meTTa",
+          "meTTaLog"
+        ],
+        "configuration": "./metta.config.json",
+        "extensions": [
+          ".metta"
+        ]
+      }
+    ]
+  },
+  "dependencies": {
+    "vscode-languageclient": "^9.0.1"
+  },
+  "devDependencies": {
+    "vscode": "^1.1.6"
+  }
+}