diff --git a/CHANGES.md b/CHANGES.md
index 0b7c25e084..fe616b8025 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -11,6 +11,7 @@
 * Named character references without a semicolon before `-` or `_` now decode correctly in attribute values, matching HTML and browser behavior (e.g., `&copy-` becomes `©-`). [#2588](https://github.com/jhy/jsoup/issues/2588)
 * Support downloads > 2GB via `Response.bodyStream()` when `maxBodySize(0)` is configured. [#2593](https://github.com/jhy/jsoup/issues/2593)
 * Updated table and table-fragment parsing to place misnested content correctly per the HTML5 spec. For example, `<table><b><p>X</b>` places the paragraph before the table. [#2601](https://github.com/jhy/jsoup/issues/2601)
+* `StreamParser` now preserves its progress if you use the same `Parser` to parse another document, or call `Element.append(String)` on a streamed element. Previously, these operations replaced the active parse state and prevented streaming from continuing correctly. [#2605](https://github.com/jhy/jsoup/issues/2605)
 * Updated the adoption-agency algorithm to match the current HTML5 spec and to preserve formatting order when recovering misnested elements. [#2604](https://github.com/jhy/jsoup/pull/2604)
 
 ## 1.23.2 (2026-Aug-26)
diff --git a/src/main/java/org/jsoup/parser/StreamParser.java b/src/main/java/org/jsoup/parser/StreamParser.java
index 607c1ad16f..3e52bebd1c 100644
--- a/src/main/java/org/jsoup/parser/StreamParser.java
+++ b/src/main/java/org/jsoup/parser/StreamParser.java
@@ -57,18 +57,19 @@ Selectors that depend on knowing all siblings (e.g. {@code :last-child}, {@code
  @since 1.18.1 */
 public class StreamParser implements Closeable {
     final private Parser parser;
-    final private TreeBuilder treeBuilder;
+    final TreeBuilder treeBuilder;
     final private ElementIterator it = new ElementIterator();
     @Nullable private Document document;
-    private boolean stopped = false;
+    private boolean stopped = true;
 
     /**
      Construct a new StreamParser, using the supplied base Parser.
+     The supplied parser provides configuration and collects parse errors; streaming uses an independent tree builder.
      @param parser the configured base parser
      */
     public StreamParser(Parser parser) {
         this.parser = parser;
-        treeBuilder = parser.getTreeBuilder();
+        treeBuilder = parser.getTreeBuilder().newInstance();
         treeBuilder.nodeListener(it);
     }
 
@@ -180,7 +181,6 @@ read. Structural changes (e.g. insert, remove) may be made to the Document conte
      @return the (partial) Document
      */
     public Document document() {
-        document = treeBuilder.doc;
         Validate.notNull(document, "Must run parse() before calling.");
         return document;
     }
diff --git a/src/test/java/org/jsoup/parser/HtmlTreeBuilderTest.java b/src/test/java/org/jsoup/parser/HtmlTreeBuilderTest.java
index c61eddca06..6e0f19ed89 100644
--- a/src/test/java/org/jsoup/parser/HtmlTreeBuilderTest.java
+++ b/src/test/java/org/jsoup/parser/HtmlTreeBuilderTest.java
@@ -8,6 +8,7 @@
 import org.junit.jupiter.api.Test;
 
 import java.io.IOException;
+import java.io.StringReader;
 import java.lang.annotation.Annotation;
 import java.util.ArrayList;
 import java.util.List;
@@ -130,11 +131,16 @@ public class HtmlTreeBuilderTest {
     // exercise an adoption error, then verify that the parser can consume the remaining input
     private static void assertAdoptionRecovery(HtmlTreeBuilder tb, Consumer<HtmlTreeBuilder> exercise, String message) throws IOException {
         Parser parser = new Parser(tb).setTrackErrors(20);
-        try (StreamParser stream = new StreamParser(parser).parseFragment("<p>After</p>", new Element("div"), "")) {
+        tb.initialiseParse(new StringReader("<p>After</p>"), "", parser);
+        tb.initialiseParseFragment(new Element("div"));
+        try {
             exercise.accept(tb);
             assertTrue(parser.getErrors().stream().anyMatch(error -> error.getErrorMessage().equals(message)),
                 () -> "Expected error: " + message + "; got: " + parser.getErrors());
-            assertEquals("After", stream.complete().text());
+            tb.runParser();
+            assertEquals("After", tb.doc.text());
+        } finally {
+            tb.closeParse();
         }
     }
 
@@ -185,7 +191,7 @@ private static void assertAdoptionRecovery(HtmlTreeBuilder tb, Consumer<HtmlTree
         // a table removed while still open uses the element above it on the stack
         Parser parser = Parser.htmlParser();
         try (StreamParser stream = new StreamParser(parser).parseFragment("", new Element("div"), "")) {
-            HtmlTreeBuilder tb = (HtmlTreeBuilder) parser.getTreeBuilder();
+            HtmlTreeBuilder tb = (HtmlTreeBuilder) stream.treeBuilder;
             Element container = stream.document().child(0);
             Element table = container.appendElement("table");
             tb.push(table);
@@ -239,10 +245,9 @@ public void nonnull() {
 
     @Test void tracksParseLifecycle() throws IOException {
         Parser parser = Parser.htmlParser();
-        TreeBuilder treeBuilder = parser.getTreeBuilder();
-        assertFalse(treeBuilder.isComplete());
-
         try (StreamParser streamParser = new StreamParser(parser).parse("<title>One</title><p id=hit>Full</p>", "")) {
+            TreeBuilder treeBuilder = streamParser.treeBuilder;
+            assertFalse(treeBuilder.isComplete());
             streamParser.expectFirst("title");
             Element open = streamParser.document().expectFirst("#hit");
             assertTrue(treeBuilder.isOpen(open));
diff --git a/src/test/java/org/jsoup/parser/StreamParserTest.java b/src/test/java/org/jsoup/parser/StreamParserTest.java
index 2f24613de7..a6f288a1bc 100644
--- a/src/test/java/org/jsoup/parser/StreamParserTest.java
+++ b/src/test/java/org/jsoup/parser/StreamParserTest.java
@@ -96,6 +96,72 @@ void canStreamXml() {
         assertEquals("", seen3.toString());
     }
 
+    @Test void streamsAfterParserReuse() throws IOException {
+        Parser parser = Parser.htmlParser();
+        try (StreamParser streamer = new StreamParser(parser).parse("<p>One</p><p>Two</p>", "")) {
+            Document doc = streamer.document();
+            assertSame(parser, doc.parser());
+            assertEquals("One", streamer.expectFirst("p").text());
+
+            Document ordinary = parser.parseInput("<div>Other</div>", "");
+            assertEquals("Other", ordinary.body().text());
+
+            assertSame(doc, streamer.document());
+            assertEquals("Two", streamer.selectNext("p").text());
+            assertEquals("<p>One</p>\n<p>Two</p>", streamer.complete().body().html());
+        }
+    }
+
+    @Test void streamsAfterHtmlAppend() throws IOException {
+        Parser parser = Parser.htmlParser();
+        try (StreamParser streamer = new StreamParser(parser).parse("<p>One</p><p>Two</p>", "")) {
+            Document doc = streamer.document();
+            assertSame(parser, doc.parser());
+            Element first = streamer.expectFirst("p");
+            assertEquals("One", first.text());
+
+            first.append("<b>Added</b>");
+            assertEquals("One<b>Added</b>", first.html());
+
+            assertSame(doc, streamer.document());
+            assertEquals("Two", streamer.selectNext("p").text());
+            assertEquals("<p>One<b>Added</b></p>\n<p>Two</p>", streamer.complete().body().html());
+        }
+    }
+
+    @Test void sharesParserSettingsAndErrors() throws IOException {
+        Parser parser = Parser.htmlParser();
+        try (StreamParser streamer = new StreamParser(parser)) {
+            parser.settings(ParseSettings.preserveCase).setTrackPosition(true).setTrackErrors(10);
+            Document doc = streamer.parse("<P ID=one>One</P></span>", "").complete();
+
+            assertSame(parser, doc.parser());
+            Element p = doc.expectFirst("P");
+            assertEquals("P", p.tagName());
+            assertTrue(p.attributes().hasKey("ID"));
+            assertTrue(p.sourceRange().isTracked());
+            assertFalse(parser.getErrors().isEmpty());
+        }
+    }
+
+    @Test void iteratorEmptyBeforeParse() {
+        try (StreamParser streamer = new StreamParser(Parser.htmlParser())) {
+            Iterator<Element> iterator = streamer.iterator();
+            assertFalse(iterator.hasNext());
+            assertThrows(NoSuchElementException.class, iterator::next);
+        }
+    }
+
+    @Test void parserReuseDoesNotStartStream() {
+        Parser parser = Parser.htmlParser();
+        try (StreamParser streamer = new StreamParser(parser)) {
+            parser.parseInput("<p>Other</p>", "");
+
+            assertThrows(IllegalArgumentException.class, streamer::document);
+            assertFalse(streamer.iterator().hasNext());
+        }
+    }
+
     @Test void canStopAndCompleteAndReuse() throws IOException {
         StreamParser parser = new StreamParser(Parser.htmlParser());
         String html1 = "<p id=one>One<p id=two>Two";
@@ -526,12 +592,11 @@ static StreamParser basic() {
     }
 
     static boolean isClosed(StreamParser streamer) {
-        // a bit of a back door in!
         return getReader(streamer) == null;
     }
 
-     private static CharacterReader getReader(StreamParser streamer) {
-        return streamer.document().parser().getTreeBuilder().reader;
+    private static CharacterReader getReader(StreamParser streamer) {
+        return streamer.treeBuilder.reader;
     }
 
     @Test void doesNotReadPastParse() throws IOException {
@@ -694,7 +759,7 @@ void canStreamFragment() {
             .parseFragment("<div>One</div><div>Two</div>", context, "")) {
             Element container = parser.expectFirst("#context");
             assertEquals("One Two", container.text());
-            assertFalse(parser.document().parser().getTreeBuilder().isOpen(container));
+            assertFalse(parser.treeBuilder.isOpen(container));
             assertSame(parser.document().child(0), container);
             assertEquals(container.childNodes(), parser.completeFragment());
         }