footnotes: numeric footnotes auto increment

znai-core/src/main/java/org/testingisdocumenting/znai/extensions/footnote/FootnoteId.java

@@ -17,11 +17,4 @@
 package org.testingisdocumenting.znai.extensions.footnote;
 
 public record FootnoteId(String id) {
-    public int asNumber() {
-        return Integer.parseInt(id);
-    }
-
-    public boolean isNumber() {
-        return id != null && id.matches("\\d+");
-    }
 }

znai-core/src/main/java/org/testingisdocumenting/znai/parser/commonmark/MarkdownParser.java

@@ -68,6 +68,11 @@ public MarkupParserResult parse(Path path, String markdown) {
         Node node = fullParser.parse(markdown);
         MarkdownVisitor visitor = parsePartial(node, path, parserHandler);
 
+        if (!visitor.getUnresolvedFootnoteRefs().isEmpty()) {
+            throw new IllegalArgumentException("undefined footnote reference(s): " +
+                    String.join(", ", visitor.getUnresolvedFootnoteRefs()));
+        }
+
         if (visitor.hasPluginWarnings()) {
             reportWarnings(path, visitor.getParameterWarnings());
         }

znai-core/src/main/java/org/testingisdocumenting/znai/parser/commonmark/MarkdownVisitor.java

@@ -44,20 +44,26 @@
 
 import java.nio.file.Path;
 import java.util.*;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public class MarkdownVisitor extends AbstractVisitor {
+    private static final Pattern FOOTNOTE_REFERENCE_PATTERN = Pattern.compile("\\[\\^([^]]+)]");
+
     private final ComponentsRegistry componentsRegistry;
     private final Path path;
     private final ParserHandler parserHandler;
     private boolean sectionStarted;
 
     private final Set<PluginParamWarning> parameterWarnings;
+    private final Set<String> unresolvedFootnoteRefs;
 
     public MarkdownVisitor(ComponentsRegistry componentsRegistry, Path path, ParserHandler parserHandler) {
         this.componentsRegistry = componentsRegistry;
         this.path = path;
         this.parserHandler = parserHandler;
         this.parameterWarnings = new LinkedHashSet<>();
+        this.unresolvedFootnoteRefs = new LinkedHashSet<>();
     }
 
     public boolean isSectionStarted() {
@@ -72,6 +78,10 @@ public Set<PluginParamWarning> getParameterWarnings() {
         return parameterWarnings;
     }
 
+    public Set<String> getUnresolvedFootnoteRefs() {
+        return unresolvedFootnoteRefs;
+    }
+
     @Override
     public void visit(Paragraph paragraph) {
         parserHandler.onParagraphStart();
@@ -95,7 +105,13 @@ public void visit(StrongEmphasis strongEmphasis) {
 
     @Override
     public void visit(Text text) {
-        parserHandler.onSimpleText(text.getLiteral());
+        String literal = text.getLiteral();
+        Matcher matcher = FOOTNOTE_REFERENCE_PATTERN.matcher(literal);
+        while (matcher.find()) {
+            unresolvedFootnoteRefs.add(matcher.group(1));
+        }
+
+        parserHandler.onSimpleText(literal);
     }
 
     @Override

znai-core/src/main/java/org/testingisdocumenting/znai/parser/docelement/DocElementCreationParserHandler.java

@@ -225,10 +225,7 @@ public void onTable(MarkupTableData tableData) {
     public void onFootnoteDefinition(ParsedFootnote footnote) {
         parsedFootnotes.put(footnote.id(), footnote);
 
-        int indexToUse = footnote.id().isNumber() ?
-            footnote.id().asNumber():
-            ++footnoteAutoIdx;
-
+        int indexToUse = ++footnoteAutoIdx;
         footnoteIdxById.put(footnote.id(), indexToUse);
     }
 

znai-core/src/test/groovy/org/testingisdocumenting/znai/parser/MarkdownParserTest.groovy

@@ -617,15 +617,15 @@ after footnote
                         ["type": "SoftLineBreak"],
                         ["text": "numeric one ", "type": "SimpleText"],
                         [
-                            "label": "5",
+                            "label": "3",
                             "content": [["type": "Paragraph", "content": [["text": "footnote num5", "type": "SimpleText"]]]],
                             "type": "FootnoteReference"
                         ],
                         ["text": " what do we do with this one", "type": "SimpleText"],
                         ["type": "SoftLineBreak"],
                         ["text": "and what do we do with this ", "type": "SimpleText"],
                         [
-                            "label": "8",
+                            "label": "4",
                             "content": [["type": "Paragraph", "content": [["text": "footnote num8", "type": "SimpleText"]]]],
                             "type": "FootnoteReference"
                         ]
@@ -637,6 +637,16 @@ after footnote
         ]
     }
 
+    @Test
+    void "undefined footnote reference"() {
+        code {
+            parse("text with [^undefined] reference")
+        } should throwException(~/undefined footnote reference\(s\): undefined/)
+
+        parse("text with `[^undefined]` reference")
+        parse("```[^ref]```")
+    }
+
     @Test
     void "embedded html block"() {
         parse("""

znai-docs/znai/flow/footnotes.md

@@ -18,6 +18,9 @@ To add a reference to the footnote use `[^my-id]` which will result in [^my-id]
     Constructor()
     ```
 
+Note: numeric footnotes are treated as text footnotes, and they will be assigned the auto incremented 
+number in order of appearance.
+
 # Preview
 
 Hover mouse over a footnote reference see its content in a tooltip.

znai-docs/znai/release-notes/1.88/add-2026-04-09-footnotes-numeric-auto-increment.md

@@ -0,0 +1 @@
+* Add: numeric Footnotes auto increment and ignore the given numeric value

znai-docs/znai/release-notes/1.88/add-2026-04-11-undefined-footnote-ref.md

@@ -0,0 +1 @@
+* Add: Undefined footnote references fail the build