diff --git a/core/modules/parsers/wikiparser/rules/codeinline.js b/core/modules/parsers/wikiparser/rules/codeinline.js
index 5606ba478..73e3484aa 100644
--- a/core/modules/parsers/wikiparser/rules/codeinline.js
+++ b/core/modules/parsers/wikiparser/rules/codeinline.js
@@ -31,13 +31,16 @@ exports.parse = function() {
 	reEnd.lastIndex = this.parser.pos;
 	var match = reEnd.exec(this.parser.source),
 		text,
-		start = this.parser.pos;
+		start = this.parser.pos,
+		textEnd;
 	// Process the text
 	if(match) {
 		text = this.parser.source.substring(this.parser.pos,match.index);
+		textEnd = match.index;
 		this.parser.pos = match.index + match[0].length;
 	} else {
 		text = this.parser.source.substr(this.parser.pos);
+		textEnd = this.parser.sourceLength;
 		this.parser.pos = this.parser.sourceLength;
 	}
 	return [{
@@ -47,7 +50,7 @@ exports.parse = function() {
 			type: "text",
 			text: text,
 			start: start,
-			end: this.parser.pos
+			end: textEnd
 		}]
 	}];
 };
diff --git a/core/modules/parsers/wikiparser/rules/extlink.js b/core/modules/parsers/wikiparser/rules/extlink.js
index 7a2485f1c..ca8c13012 100644
--- a/core/modules/parsers/wikiparser/rules/extlink.js
+++ b/core/modules/parsers/wikiparser/rules/extlink.js
@@ -32,7 +32,8 @@ exports.parse = function() {
 	this.parser.pos = this.matchRegExp.lastIndex;
 	// Create the link unless it is suppressed
 	if(this.match[0].substr(0,1) === "~") {
-		return [{type: "text", text: this.match[0].substr(1), start: start, end: this.parser.pos}];
+		// Start after the suppressing "~" so the span matches the plain text
+		return [{type: "text", text: this.match[0].substr(1), start: start + 1, end: this.parser.pos}];
 	} else {
 		return [{
 			type: "element",
diff --git a/core/modules/parsers/wikiparser/rules/import.js b/core/modules/parsers/wikiparser/rules/import.js
index 65376f8be..fe291f8e3 100644
--- a/core/modules/parsers/wikiparser/rules/import.js
+++ b/core/modules/parsers/wikiparser/rules/import.js
@@ -34,7 +34,7 @@ exports.parse = function() {
 	// Parse the filter terminated by a line break
 	var reMatch = /(.*)(?:$|\r?\n)/mg;
 	reMatch.lastIndex = this.parser.pos;
-	var filterStart = this.parser.source;
+	var filterStart = this.parser.pos;
 	var match = reMatch.exec(this.parser.source);
 	this.parser.pos = reMatch.lastIndex;
 	// Parse tree nodes to return
diff --git a/core/modules/parsers/wikiparser/rules/wikilinkprefix.js b/core/modules/parsers/wikiparser/rules/wikilinkprefix.js
index c1c5db1f6..a1f63293e 100644
--- a/core/modules/parsers/wikiparser/rules/wikilinkprefix.js
+++ b/core/modules/parsers/wikiparser/rules/wikilinkprefix.js
@@ -27,9 +27,11 @@ Parse the most recent match
 */
 exports.parse = function() {
 	// Get the details of the match
-	var linkText = this.match[0];
+	var linkText = this.match[0],
+		// Start after the suppressing "~" so the span matches the plain text
+		start = this.parser.pos + 1;
 	// Move past the wikilink
 	this.parser.pos = this.matchRegExp.lastIndex;
 	// Return the link without unwikilink character as plain text
-	return [{type: "text", text: linkText.substr(1)}];
+	return [{type: "text", text: linkText.substr(1), start: start, end: this.parser.pos}];
 };
diff --git a/editions/test/tiddlers/tests/test-parsetree-positions.js b/editions/test/tiddlers/tests/test-parsetree-positions.js
new file mode 100644
index 000000000..e41dc0648
--- /dev/null
+++ b/editions/test/tiddlers/tests/test-parsetree-positions.js
@@ -0,0 +1,60 @@
+/*\
+title: test-parsetree-positions.js
+type: application/javascript
+tags: [[$:/tags/test-spec]]
+
+Regression tests for #9882: wikitext parser rules must emit accurate
+`start`/`end` source positions on their parse tree nodes. Tooling that maps
+rendered output back to the source text relies on these offsets.
+
+\*/
+
+"use strict";
+
+describe("Parse tree source position tests (#9882)", function() {
+
+	// Create a wiki
+	var wiki = $tw.test.wiki();
+
+	// Define a parsing shortcut
+	var parse = function(text) {
+		return wiki.parseText("text/vnd.tiddlywiki",text).tree;
+	};
+
+	it("should give inline code runs a text node that spans only the code, not the backticks", function() {
+		// codeinline.js: `code` gives a text node "code" spanning offsets 1 to 5. The closing backtick at 5 is excluded.
+		// Bug: `end` was set to `this.parser.pos`, which sits past the closing backtick, so end was 6 and the span swallowed the backtick.
+		expect(parse("`code`")).toEqual(
+			[ { type: "element", tag: "p", rule: "parseblock", start: 0, end: 6, children: [ { type: "element", tag: "code", rule: "codeinline", start: 0, end: 6, children: [ { type: "text", text: "code", start: 1, end: 5 } ] } ] } ]
+		);
+		// ``a`b`` gives text "a`b" spanning 2 to 5. `end` must be the offset of the closing marker whatever its length.
+		// Bug: `end` was `this.parser.pos` (7), two characters past the code, so it also swallowed the closing ``.
+		expect(parse("``a`b``")).toEqual(
+			[ { type: "element", tag: "p", rule: "parseblock", start: 0, end: 7, children: [ { type: "element", tag: "code", rule: "codeinline", start: 0, end: 7, children: [ { type: "text", text: "a`b", start: 2, end: 5 } ] } ] } ]
+		);
+	});
+
+	it("should start the text node of a suppressed external link after the ~", function() {
+		// extlink.js: ~https://example.com/ emits the plain text "https://example.com/", which spans offsets 1 to 21.
+		// Bug: `start` was the offset of the ~ (0), so the span was one character too wide and began on the ~ that the text omits.
+		expect(parse("~https://example.com/")).toEqual(
+			[ { type: "element", tag: "p", rule: "parseblock", start: 0, end: 21, children: [ { type: "text", text: "https://example.com/", start: 1, end: 21, rule: "extlink" } ] } ]
+		);
+	});
+
+	it("should give a suppressed wikilink's text node source positions", function() {
+		// wikilinkprefix.js: ~SuppressedLink emits the plain text "SuppressedLink", spanning offsets 1 to 15.
+		// Bug: the text node carried no `start`/`end` at all. The parser framework then defaulted `start` to the ~ offset (0).
+		expect(parse("~SuppressedLink")).toEqual(
+			[ { type: "element", tag: "p", rule: "parseblock", start: 0, end: 15, children: [ { type: "text", text: "SuppressedLink", start: 1, end: 15, rule: "wikilinkprefix" } ] } ]
+		);
+	});
+
+	it("should record the filter's start offset for an \\import pragma", function() {
+		// import.js: \import [tag[x]] records the filter value "[tag[x]]" starting at offset 8, right after "\import ".
+		// Bug: `filterStart` was assigned `this.parser.source` (the whole source string) instead of `this.parser.pos`, so `start` was a string, not an offset.
+		expect(parse("\\import [tag[x]]\n")).toEqual(
+			[ { type: "importvariables", rule: "import", start: 0, end: 16, attributes: { filter: { type: "string", value: "[tag[x]]", start: 8, end: 16 } }, children: [] } ]
+		);
+	});
+});
diff --git a/editions/tw5.com/tiddlers/releasenotes/5.4.1/#9882/#9882-fix-invalid-source-positions.tid b/editions/tw5.com/tiddlers/releasenotes/5.4.1/#9882/#9882-fix-invalid-source-positions.tid
new file mode 100644
index 000000000..b833ec348
--- /dev/null
+++ b/editions/tw5.com/tiddlers/releasenotes/5.4.1/#9882/#9882-fix-invalid-source-positions.tid
@@ -0,0 +1,21 @@
+title: $:/changenotes/5.4.1/#9882
+created: 20260701142414000
+modified: 20260701142414000
+description: Fix invalid source positions in parse tree nodes
+release: 5.4.1
+tags: $:/tags/ChangeNote
+change-type: bugfix
+change-category: internal
+github-links: https://github.com/TiddlyWiki/TiddlyWiki5/pull/9882
+github-contributors: pmario
+type: text/vnd.tiddlywiki
+
+Several wikitext parser rules emitted parse tree nodes with missing or incorrect `start` and `end` source positions. Accurate positions are needed by tooling that maps rendered output back to the source text.
+
+* ''Inline code'' (`` `code` ``): the text node `end` no longer runs past the closing backtick, so the span covers only the code text.
+
+* ''Suppressed external links'' (`~https://example.com`): the text node now starts after the suppressing `~`, matching the plain text that is emitted.
+
+* ''Suppressed wikilinks'' (`~SuppressedLink`): the text node now carries `start` and `end` positions. Previously it had none.
+
+* ''Import filter'' (`\import`): the filter start position was set to the whole source string instead of the current parse position. It now uses the correct offset.