fix: pipe Typos diagnostic now highlights only the broken pipe name.

PROBLEMS.md

@@ -264,6 +264,29 @@ User's custom layout silently ignored, defaults used.
 (Same as B1 — restated here for the template-authoring perspective.) One bad
 tag → whole page `""`. The most impactful silent failure in the system.
 
+### G3. Pipe errors lack "did you mean?" suggestions — High
+`mustache/pipes.odin:241`
+
+Unknown key errors (`{{tittle}}`), missing partials, and unmatched block
+overrides all get Levenshtein "did you mean?" hints via `suggest_correction`.
+But unknown pipe operations (`{{date | formats}}`) get only `"unknown pipe op
+'formats'"` with no suggestion. The known filter names (`"format"`,
+`"group_by"`) are a small fixed set — perfect for suggestions.
+
+Structural gap: `Error_Body` has no `hint` field, and
+`format_render_error` doesn't pass `hint` to `format_error` (defaults to
+`""`). So even if a suggestion were computed, there's nowhere to put it
+without either appending to `msg` or adding `hint` to `Error_Body`.
+
+### G4. Triple-mustache `{{{` mishandled by `tag_content_base` — Medium
+`mustache/mustache.odin:230`
+
+`tag_content_base` skips `{{` and sigils (`#^/&><$!`) to find where tag
+content begins. But triple-mustache `{{{key}}}` is common — after `{{`,
+the next char is `{`, which is not in the sigil list, so `base` points at
+`{` instead of the actual key content. Any pipe position calculation for
+`{{{key | format}}}` will be off by one byte.
+
 ---
 
 ## Cross-cutting themes

TODOS.md

@@ -22,6 +22,11 @@
   - [ ] Need to be careful about diagnostics across module boundaries.
     - we don't necessarily want to warn users about theme designers mistakes. (though perhaps we do)
   - [ ] consider reporting duplicate weights outside of menus
+  - [ ] Extend `tag_error` to all render-time errors, not just pipe errors.
+    Currently only pipe errors (4 sites in `render_nodes`) get stamped with
+    the correct template source/path. Other render errors still use the
+    content template's source/path, which can point at the wrong file.
+  - [ ] try to make file paths clickable links.
 - [ ] Load grammars dynamically
 - [ ] starred must be a param.
 - [ ] Documentation
@@ -36,6 +41,7 @@
 - [ ] cleanup `#partial switch`es.
 - [ ] improve json diagnostics.
   - i.e. "Missing quotes around string", etc.
+- [ ] don't use bullshit "sub-tokens", add filters and pipes as proper tokens.
 
 ## Performance
 

mustache/diagnostic.odin

@@ -185,6 +185,7 @@ format_error :: proc(
 	context_before: int = 2,
 	context_after: int = 2,
 	colorize: bool = false,
+	span: int = 0,
 ) -> string {
 	line, col := line_col(source, pos)
 	total_lines := count_lines(source)
@@ -232,8 +233,11 @@ format_error :: proc(
 	write_gutter(&sb, width, faint, reset)
 
 	// Caret extent for the error line.
-	_, token_start, token_end := context_extent(source, pos)
-	line_start, _, _ := context_extent(source, pos)
+	line_start, token_start, token_end := context_extent(source, pos)
+	if span > 0 {
+		token_start = pos
+		token_end = pos + span
+	}
 	caret_start_col := token_start - line_start + 1
 	caret_end_col := token_end - line_start + 1
 	if caret_end_col <= caret_start_col {
@@ -322,5 +326,5 @@ format_render_error :: proc(err: Error, tmpl: Template, colorize: bool = false)
 	if path == "" {
 		path = "<input>"
 	}
-	return format_error(path, source, b.pos, b.msg, colorize = colorize)
+	return format_error(path, source, b.pos, b.msg, colorize = colorize, span = b.span)
 }

mustache/mustache.odin

@@ -31,6 +31,7 @@ Error_Body :: struct {
 	kind:   Error_Kind,
 	source: string,
 	path:   string,
+	span:   int,
 }
 
 // Error is nil when no error occurred.
@@ -57,6 +58,7 @@ tag_error :: proc(err: Error, tmpl: Template) -> Error {
 	return Error_Body {
 		msg    = b.msg,
 		pos    = b.pos,
+		span   = b.span,
 		kind   = b.kind,
 		source = tmpl.source,
 		path   = tmpl.path,
@@ -225,6 +227,22 @@ parse_tokens :: proc(
 	return
 }
 
+// tag_content_base returns the absolute byte offset in source where the
+// trimmed tag content begins (after {{, optional sigil, and whitespace).
+tag_content_base :: proc(source: string, tag_pos: int) -> int {
+	base := tag_pos + 2 // skip {{
+	if base < len(source) {
+		switch source[base] {
+		case '#', '^', '/', '&', '>', '<', '$', '!':
+			base += 1
+		}
+	}
+	for base < len(source) && (source[base] == ' ' || source[base] == '\t') {
+		base += 1
+	}
+	return base
+}
+
 parse_section :: proc(
 	tokens: []Token,
 	pos: ^int,
@@ -245,7 +263,7 @@ parse_section :: proc(
 		case .Variable:
 			idx := len(nodes)
 			append(nodes, Node{kind = .Variable})
-			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos)
+			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos, tag_content_base(source, tok.pos))
 			if perr != nil {
 				return Error_Body {
 					msg = fmt.tprintf("pipe parse error in '{{{{%s}}}}': %v", tok.value, perr),
@@ -259,7 +277,7 @@ parse_section :: proc(
 		case .Unescaped:
 			idx := len(nodes)
 			append(nodes, Node{kind = .Unescaped})
-			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos)
+			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos, tag_content_base(source, tok.pos))
 			if perr != nil {
 				return Error_Body {
 					msg = fmt.tprintf("pipe parse error in '{{{{&%s}}}}': %v", tok.value, perr),
@@ -279,7 +297,7 @@ parse_section :: proc(
 			content_start := 0
 			if pos^ < len(tokens) {content_start = tokens[pos^].pos}
 			append(nodes, Node{kind = .Section, pos = tok.pos})
-			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos)
+			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos, tag_content_base(source, tok.pos))
 			if perr != nil {
 				return Error_Body {
 					msg = fmt.tprintf("pipe parse error in '{{{{#%s}}}}': %v", tok.value, perr),
@@ -300,7 +318,7 @@ parse_section :: proc(
 			content_start := 0
 			if pos^ < len(tokens) {content_start = tokens[pos^].pos}
 			append(nodes, Node{kind = .Inverted, pos = tok.pos})
-			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos)
+			pipe_key, perr := parse_pipeline(tok.value, &nodes[idx].filters, tok.pos, tag_content_base(source, tok.pos))
 			if perr != nil {
 				return Error_Body {
 					msg = fmt.tprintf("pipe parse error in '{{{{^%s}}}}': %v", tok.value, perr),

mustache/pipes.odin

@@ -19,6 +19,7 @@ DEFAULT_DATE_FORMAT :: "2 Jan 2006"
 Pipe_Filter :: struct {
 	op:     string,
 	args:   [dynamic; MAX_PIPE_ARGS]string,
+	op_pos: int,
 }
 
 Group :: struct {
@@ -77,6 +78,7 @@ parse_pipeline :: proc(
 	content: string,
 	filters_out: ^[dynamic; MAX_PIPES]Pipe_Filter,
 	pos: int,
+	content_base: int,
 ) -> (
 	key: string,
 	err: Error,
@@ -86,14 +88,13 @@ parse_pipeline :: proc(
 		return key, nil
 	}
 
-	segments := strings.split(content, "|", allocator = context.temp_allocator)
-
-	filter_count := len(segments) - 1
-	if filter_count > MAX_PIPES {
+	// Count pipes to validate against MAX_PIPES.
+	pipe_count := strings.count(content, "|")
+	if pipe_count > MAX_PIPES {
 		return "", Error_Body {
 			msg = fmt.tprintf(
 				"pipe expression has %d filters, max is %d",
-				filter_count,
+				pipe_count,
 				MAX_PIPES,
 			),
 			pos = pos,
@@ -101,21 +102,38 @@ parse_pipeline :: proc(
 		}
 	}
 
-	key = strings.trim_space(segments[0])
+	// Key is everything before the first |.
+	first_pipe := strings.index(content, "|")
+	key = strings.trim_space(content[:first_pipe])
 	if len(key) == 0 {
 		return "", Error_Body{msg = "pipe expression missing key", pos = pos, kind = .Syntax}
 	}
 
-	if filter_count == 0 {
+	if pipe_count == 0 {
 		return key, nil
 	}
 
-	for i in 0 ..< filter_count {
-		seg := strings.trim_space(segments[i + 1])
+	// Walk pipe-delimited segments, tracking byte offsets within content.
+	seg_start := first_pipe + 1 // offset in content, just after |
+	for seg_start <= len(content) {
+		next_pipe := strings.index(content[seg_start:], "|")
+
+		// Raw segment text (may have leading/trailing whitespace).
+		seg_end := seg_start + next_pipe if next_pipe >= 0 else len(content)
+		raw_seg := content[seg_start:seg_end]
+
+		// Count leading whitespace to find op offset within content.
+		ws := 0
+		for ws < len(raw_seg) && is_pipe_space(raw_seg[ws]) {
+			ws += 1
+		}
+		seg := strings.trim_space(raw_seg)
 		if len(seg) == 0 {
 			return "", Error_Body{msg = "empty filter", pos = pos, kind = .Syntax}
 		}
 
+		op_offset_in_content := seg_start + ws
+
 		tokens, terr := tokenize_fields(seg, pos)
 		if terr != nil {
 			delete(tokens)
@@ -141,12 +159,18 @@ parse_pipeline :: proc(
 
 		filter := Pipe_Filter {
 			op     = tokens[0],
+			op_pos = content_base + op_offset_in_content,
 		}
 		for j in 1 ..< len(tokens) {
 			append(&filter.args, tokens[j])
 		}
 		append(filters_out, filter)
 		delete(tokens)
+
+		if next_pipe < 0 {
+			break
+		}
+		seg_start = seg_end + 1
 	}
 
 	return key, nil
@@ -240,7 +264,8 @@ apply_filter :: proc(value: any, filter: ^Pipe_Filter, pos: int, ctx: []any) ->
 	case:
 		return nil, Error_Body {
 			msg  = fmt.tprintf("unknown pipe op '%s'", filter.op),
-			pos = pos,
+			pos  = filter.op_pos,
+			span = len(filter.op),
 			kind = .Data,
 		}
 	}