feat: complete BLOCK_LIST/ADDR_LIST keywords and space comments

Add keyword-driven completions for BLOCK_LIST and ADDR_LIST in the LSP server.
- While typing a prefix of these keywords the server returns the keyword(s)
  as incomplete snippet suggestions that trigger a re-request.
- Once the keyword is typed the server replaces it with a full list of the
  corresponding loaded block templates or addresses (quoted), and sets each
  item's filter_text to include the keyword so further typing narrows results.
- Integrate this flow into on_completion and factor the symbol-list logic
  into a helper that returns either incomplete keyword suggestions or the
  completed symbol list.

Also implement NxFormatter.format_comment to ensure a single space after a
leading '#' for comments that don't already start with whitespace, while
leaving sequences of '#' (separators), shebangs, and already-spaced comments
unchanged. This affects both standalone and inline comments.

Add/rename tests to cover the new completions and comment-spacing behavior.

server/src/lsp_server.py

@@ -85,6 +85,7 @@ from tools.tcl_command_completion import (
     TCL_COMMAND_ITEMS,
     TCL_COMMAND_NAMES,
     DynamicCompletionKind,
+    line_prefix_at_position,
     path_completion_items,
     tcl_argument_completion,
 )
@@ -279,6 +280,66 @@ def document_diagnostic(params: lsp.DocumentDiagnosticParams):
     lsp.CompletionOptions(trigger_characters=["$", " ", "-", "(", ","]),
 )
 def on_completion(params: lsp.CompletionParams) -> lsp.CompletionList:
+    result = _on_completion(params)
+    doc = LSP_SERVER.workspace.get_text_document(params.text_document.uri)
+    symbol_list = _symbol_list_completion(LSP_SERVER.get_lines(doc), params.position)
+    if symbol_list is not None and symbol_list.is_incomplete:
+        # Re-request while typing so the full list appears at BLOCK_LIST/ADDR_LIST.
+        result.items = [*symbol_list.items, *result.items]
+        result.is_incomplete = True
+    return result
+
+
+# Keywords that expand to all loaded .def names: keyword -> (items, description).
+SYMBOL_LIST_KEYWORDS = {
+    "BLOCK_LIST": (lambda: LSP_SERVER.block_template_items(), "block templates"),
+    "ADDR_LIST": (lambda: LSP_SERVER.address_items(), "addresses"),
+}
+_WORD_BEFORE_CURSOR_RE = re.compile(r"(?<![$\w])[A-Za-z_]+$")
+
+
+def _symbol_list_completion(source_lines, position: lsp.Position) -> lsp.CompletionList | None:
+    """Complete BLOCK_LIST/ADDR_LIST to all loaded block templates/addresses.
+
+    While the typed word is a prefix of a keyword, an incomplete list with the
+    keyword itself is returned. Once the keyword is typed, the complete list of
+    quoted names replaces it.
+    """
+    line_prefix = line_prefix_at_position(source_lines, position)
+    match = _WORD_BEFORE_CURSOR_RE.search(line_prefix or "")
+    if match is None:
+        return None
+    word = match.group()
+    for keyword, (symbol_items, _) in SYMBOL_LIST_KEYWORDS.items():
+        if not word.startswith(keyword):
+            continue
+        items = []
+        ranked = ranked_completion_items(((0, item) for item in symbol_items()), CompletionContext.GENERAL)
+        for item in ranked:
+            item = _quoted_item(item, source_lines, position, word)
+            # Keep every name visible for the typed keyword; text after it narrows.
+            item.filter_text = f"{keyword}{item.label}"
+            items.append(item)
+        return lsp.CompletionList(is_incomplete=False, items=items)
+
+    keywords = [
+        lsp.CompletionItem(
+            label=keyword,
+            kind=lsp.CompletionItemKind.Snippet,
+            detail=f"Show all loaded {description}",
+            insert_text=keyword,
+            sort_text=f"000:{keyword.casefold()}",
+            command=lsp.Command(title=f"Show {description}", command="editor.action.triggerSuggest"),
+        )
+        for keyword, (_, description) in SYMBOL_LIST_KEYWORDS.items()
+        if keyword.startswith(word)
+    ]
+    if keywords:
+        return lsp.CompletionList(is_incomplete=True, items=keywords)
+    return None
+
+
+def _on_completion(params: lsp.CompletionParams) -> lsp.CompletionList:
     doc = LSP_SERVER.workspace.get_text_document(params.text_document.uri)
     position = params.position
     source_lines = LSP_SERVER.get_lines(doc)
@@ -302,6 +363,10 @@ def on_completion(params: lsp.CompletionParams) -> lsp.CompletionList:
         return lsp.CompletionList(is_incomplete=False, items=array_items)
     context = completion_context(source_lines, position)
 
+    symbol_list = _symbol_list_completion(source_lines, position)
+    if symbol_list is not None and symbol_list.is_incomplete is False:
+        return symbol_list
+
     # Variable completion wins inside command arguments. Otherwise prefer the
     # narrow command grammar when the cursor is at a known subcommand/option.
     argument_completion = None

server/src/tools/formatter.py

@@ -12,6 +12,14 @@ class NxFormatter(BaseFormatter):
     while leaving all other formatting behavior unchanged.
     """
 
+    def format_comment(self, comment) -> List[str]:  # type: ignore[override]
+        # "#Comment" -> "# Comment". Leave "#", "##..." separators, "#!" and
+        # comments that already start with whitespace untouched.
+        value = comment.value
+        if value and not value[0].isspace() and value[0] not in "#!":
+            value = " " + value
+        return [f"#{value}"]
+
     def format_braced_expression(self, expr) -> List[str]:  # type: ignore[override]
         # This method mirrors BaseFormatter.format_braced_expression but inserts
         # a line continuation (" \") between continuation lines similar to

server/tests/python_tests/test_def_symbols.py

@@ -198,3 +198,63 @@ def test_typed_quotes_are_replaced_not_doubled(tmp_path, monkeypatch):
         )
     ).items
     assert _edit(items, "SPOS") == ('"SPOS"', (22, 26))
+
+
+def test_block_list_prefix_offers_keyword_and_stays_incomplete(tmp_path, monkeypatch):
+    server, _ = _project(tmp_path, monkeypatch)
+    uri = (tmp_path / "caller.tcl").as_uri()
+    source = "MOM_do_template BLOCK_L"
+    server.workspace.put_text_document(
+        lsp.TextDocumentItem(uri=uri, language_id="tcl", version=next(_versions), text=source)
+    )
+    result = lsp_server.on_completion(
+        lsp.CompletionParams(
+            text_document=lsp.TextDocumentIdentifier(uri=uri),
+            position=lsp.Position(line=0, character=len(source)),
+        )
+    )
+    assert result.is_incomplete
+    keyword = result.items[0]
+    assert keyword.label == "BLOCK_LIST"
+    assert keyword.command.command == "editor.action.triggerSuggest"
+
+
+def test_block_list_shows_all_templates_quoted(tmp_path, monkeypatch):
+    server, _ = _project(tmp_path, monkeypatch)
+    items = _complete(server, tmp_path, "set a 1\n    BLOCK_LIST")
+    assert [item.label for item in items] == ["external_subprogram", "steady_rest"]
+    assert _edit(items, "steady_rest") == ('"steady_rest"', (4, 14))
+    assert all(item.filter_text.startswith("BLOCK_LIST") for item in items)
+
+
+def test_block_list_ignores_variables_and_other_words(tmp_path, monkeypatch):
+    server, _ = _project(tmp_path, monkeypatch)
+    for source in ("set x $BLOCK_LIST", "set x MY_BLOCK_LIST", "set x steady"):
+        labels = [item.label for item in _complete(server, tmp_path, source)]
+        assert "BLOCK_LIST" not in labels
+
+
+def test_addr_list_shows_all_addresses_quoted(tmp_path, monkeypatch):
+    server, _ = _project(tmp_path, monkeypatch)
+    items = _complete(server, tmp_path, "MOM_force Once ADDR_LIST")
+    assert [item.label for item in items] == ["SPOS", "X"]
+    assert _edit(items, "SPOS") == ('"SPOS"', (15, 24))
+    assert all(item.filter_text.startswith("ADDR_LIST") for item in items)
+
+
+def test_addr_list_prefix_offers_keyword(tmp_path, monkeypatch):
+    server, _ = _project(tmp_path, monkeypatch)
+    uri = (tmp_path / "caller.tcl").as_uri()
+    source = "ADDR"
+    server.workspace.put_text_document(
+        lsp.TextDocumentItem(uri=uri, language_id="tcl", version=next(_versions), text=source)
+    )
+    result = lsp_server.on_completion(
+        lsp.CompletionParams(
+            text_document=lsp.TextDocumentIdentifier(uri=uri),
+            position=lsp.Position(line=0, character=len(source)),
+        )
+    )
+    assert result.is_incomplete
+    assert result.items[0].label == "ADDR_LIST"
+    assert "BLOCK_LIST" not in {item.label for item in result.items}

server/tests/python_tests/test_formatter.py

@@ -1,4 +1,4 @@
-"""Formatting of uplevel bodies."""
+"""Formatting with NxFormatter."""
 
 from tclint.format import FormatterOpts
 from tools.formatter import NxFormatter
@@ -31,3 +31,28 @@ def test_uplevel_without_level_and_with_variable_level():
     assert _format(source) == (
         "uplevel {\n\tset x 1\n}\nuplevel $lvl {\n\tset y 2\n}\nuplevel set z 3\n"
     )
+
+
+def test_comment_gets_space_after_hash():
+    source = (
+        "#Comment\n"
+        "# already spaced\n"
+        "#\tTabbed\n"
+        "#\n"
+        "##########\n"
+        "set x 1 ;#inline\n"
+        "proc a {} {\n"
+        "\t#nested\n"
+        "}\n"
+    )
+    assert _format(source) == (
+        "# Comment\n"
+        "# already spaced\n"
+        "#\tTabbed\n"
+        "#\n"
+        "##########\n"
+        "set x 1 ;# inline\n"
+        "proc a {} {\n"
+        "\t# nested\n"
+        "}\n"
+    )