From ccb0a7a3297c6d898091cab61bb96b2b5eedacd0 Mon Sep 17 00:00:00 2001
From: Felix Boehm <188768+fb55@users.noreply.github.com>
Date: Sat, 3 Oct 2026 22:55:44 +0100
Subject: [PATCH 1/2] fix(parser): count chunks before invoking tokenizer
 callbacks

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
---
 src/Parser.spec.ts | 17 +++++++++++++++++
 src/Parser.ts      |  3 ++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/Parser.spec.ts b/src/Parser.spec.ts
index 87a2fd2b..3be6304a 100644
--- a/src/Parser.spec.ts
+++ b/src/Parser.spec.ts
@@ -334,6 +334,23 @@ describe("API", () => {
         expect(events).toStrictEqual(["×", "bar", "end"]);
     });
 
+    it("should parse chunks queued after reset in a callback", () => {
+        const texts: string[] = [];
+        const parser = new Parser({
+            ontext(text) {
+                texts.push(text);
+                if (text === "first") parser.reset();
+                else if (text === "second") parser.pause();
+            },
+        });
+        parser.write("first");
+        parser.write("second");
+        parser.write("third");
+        parser.resume();
+        parser.end();
+        expect(texts).toStrictEqual(["first", "second", "third"]);
+    });
+
     it("should support custom tokenizer", () => {
         class CustomTokenizer extends Tokenizer {}
 
diff --git a/src/Parser.ts b/src/Parser.ts
index 84581c4f..1c32a925 100644
--- a/src/Parser.ts
+++ b/src/Parser.ts
@@ -790,8 +790,9 @@ export class Parser implements Callbacks {
 
         this.buffers.push(chunk);
         if (this.tokenizer.running) {
-            this.tokenizer.write(chunk);
+            // Count the chunk first, as a callback may call `reset()`.
             this.writeIndex++;
+            this.tokenizer.write(chunk);
         }
     }
 

From 35ba8a26b4e05ede4c6309b28cd29e5fa1415f78 Mon Sep 17 00:00:00 2001
From: Felix Boehm <188768+fb55@users.noreply.github.com>
Date: Sat, 3 Oct 2026 23:14:18 +0100
Subject: [PATCH 2/2] fix(parser): stop closing a stack reset by a callback

Use the matched element's position as the loop bound, so a reset inside
a close callback ends the loop without an extra condition per implied close.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
---
 src/Parser.spec.ts | 12 ++++++++++++
 src/Parser.ts      |  5 +++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/Parser.spec.ts b/src/Parser.spec.ts
index 3be6304a..e159a100 100644
--- a/src/Parser.spec.ts
+++ b/src/Parser.spec.ts
@@ -351,6 +351,18 @@ describe("API", () => {
         expect(texts).toStrictEqual(["first", "second", "third"]);
     });
 
+    it("should stop closing elements after reset in onclosetag", () => {
+        const closed: string[] = [];
+        const parser = new Parser({
+            onclosetag(name) {
+                closed.push(name);
+                if (name === "c") parser.reset();
+            },
+        });
+        parser.write("<a><b><c></a>");
+        expect(closed).toStrictEqual(["c"]);
+    });
+
     it("should support custom tokenizer", () => {
         class CustomTokenizer extends Tokenizer {}
 
diff --git a/src/Parser.ts b/src/Parser.ts
index 1c32a925..58fff47e 100644
--- a/src/Parser.ts
+++ b/src/Parser.ts
@@ -553,10 +553,11 @@ export class Parser implements Callbacks {
         if (!this.isVoidElement(name)) {
             const pos = this.stack.lastIndexOf(name);
             if (pos !== -1) {
-                for (let index = this.stack.length - 1; index > pos; index--) {
+                // A callback may have reset the stack.
+                while (this.stack.length > pos + 1) {
                     this.popElement(true);
                 }
-                this.popElement(false);
+                if (this.stack.length === pos + 1) this.popElement(false);
             } else if (this.htmlMode && name === "p") {
                 // Implicit open before close
                 this.emitOpenTag("p");