From 7ca97676de3b40ed45895af8eb56261ecbd658fa Mon Sep 17 00:00:00 2001
From: Yilei Yang <hi@mangoumbrella.com>
Date: Sat, 28 Mar 2026 17:25:35 +0000
Subject: [PATCH] Fix Python multi-line f-strings.

---
 .../definitions/python/python.test.ts         | 125 ++++++++++++++++++
 src/languages/definitions/python/python.ts    |  26 +++-
 2 files changed, 149 insertions(+), 2 deletions(-)

diff --git a/src/languages/definitions/python/python.test.ts b/src/languages/definitions/python/python.test.ts
index 019758a413..82cc4af08a 100644
--- a/src/languages/definitions/python/python.test.ts
+++ b/src/languages/definitions/python/python.test.ts
@@ -253,5 +253,130 @@ testTokenization('python', [
 				{ startIndex: 6, type: 'string.escape.python' }
 			]
 		}
+	],
+
+	// https://github.com/microsoft/monaco-editor/issues/4601
+	// Multiline triple-quoted f-strings.
+	[
+		{
+			line: 'x = f"""first line',
+			tokens: [
+				{ startIndex: 0, type: 'identifier.python' },
+				{ startIndex: 1, type: 'white.python' },
+				{ startIndex: 2, type: '' },
+				{ startIndex: 3, type: 'white.python' },
+				{ startIndex: 4, type: 'string.escape.python' },
+				{ startIndex: 8, type: 'string.python' }
+			]
+		},
+		{
+			line: 'still {var} string',
+			tokens: [
+				{ startIndex: 0, type: 'string.python' },
+				{ startIndex: 6, type: 'identifier.python' },
+				{ startIndex: 11, type: 'string.python' }
+			]
+		},
+		{
+			line: 'last line"""',
+			tokens: [
+				{ startIndex: 0, type: 'string.python' },
+				{ startIndex: 9, type: 'string.escape.python' }
+			]
+		},
+		{
+			line: 'y = 1',
+			tokens: [
+				{ startIndex: 0, type: 'identifier.python' },
+				{ startIndex: 1, type: 'white.python' },
+				{ startIndex: 2, type: '' },
+				{ startIndex: 3, type: 'white.python' },
+				{ startIndex: 4, type: 'number.python' }
+			]
+		}
+	],
+	[
+		{
+			line: "x = f'''first line",
+			tokens: [
+				{ startIndex: 0, type: 'identifier.python' },
+				{ startIndex: 1, type: 'white.python' },
+				{ startIndex: 2, type: '' },
+				{ startIndex: 3, type: 'white.python' },
+				{ startIndex: 4, type: 'string.escape.python' },
+				{ startIndex: 8, type: 'string.python' }
+			]
+		},
+		{
+			line: 'still {var} string',
+			tokens: [
+				{ startIndex: 0, type: 'string.python' },
+				{ startIndex: 6, type: 'identifier.python' },
+				{ startIndex: 11, type: 'string.python' }
+			]
+		},
+		{
+			line: "last line'''",
+			tokens: [
+				{ startIndex: 0, type: 'string.python' },
+				{ startIndex: 9, type: 'string.escape.python' }
+			]
+		},
+		{
+			line: 'y = 1',
+			tokens: [
+				{ startIndex: 0, type: 'identifier.python' },
+				{ startIndex: 1, type: 'white.python' },
+				{ startIndex: 2, type: '' },
+				{ startIndex: 3, type: 'white.python' },
+				{ startIndex: 4, type: 'number.python' }
+			]
+		}
+	],
+	[
+		{
+			line: `f'''it's fine'''`,
+			tokens: [
+				{ startIndex: 0, type: 'string.escape.python' },
+				{ startIndex: 4, type: 'string.python' },
+				{ startIndex: 13, type: 'string.escape.python' }
+			]
+		}
+	],
+	[
+		{
+			line: 'F"str {var} str"',
+			tokens: [
+				{ startIndex: 0, type: 'string.escape.python' },
+				{ startIndex: 2, type: 'string.python' },
+				{ startIndex: 6, type: 'identifier.python' },
+				{ startIndex: 11, type: 'string.python' },
+				{ startIndex: 15, type: 'string.escape.python' }
+			]
+		}
+	],
+	[
+		{
+			line: 'rf"str {var} str"',
+			tokens: [
+				{ startIndex: 0, type: 'string.escape.python' },
+				{ startIndex: 3, type: 'string.python' },
+				{ startIndex: 7, type: 'identifier.python' },
+				{ startIndex: 12, type: 'string.python' },
+				{ startIndex: 16, type: 'string.escape.python' }
+			]
+		}
+	],
+	[
+		{
+			line: 'fr"str {var} str"',
+			tokens: [
+				{ startIndex: 0, type: 'string.escape.python' },
+				{ startIndex: 3, type: 'string.python' },
+				{ startIndex: 7, type: 'identifier.python' },
+				{ startIndex: 12, type: 'string.python' },
+				{ startIndex: 16, type: 'string.escape.python' }
+			]
+		}
 	]
 ]);
diff --git a/src/languages/definitions/python/python.ts b/src/languages/definitions/python/python.ts
index e16954899b..c932f7b6ac 100644
--- a/src/languages/definitions/python/python.ts
+++ b/src/languages/definitions/python/python.ts
@@ -250,10 +250,16 @@ export const language = <languages.IMonarchLanguage>{
 		// Recognize strings, including those broken across lines with \ (but not without)
 		strings: [
 			[/'$/, 'string.escape', '@popall'],
-			[/f'{1,3}/, 'string.escape', '@fStringBody'],
+			[/[fF][rR]?'''/, 'string.escape', '@fTripleStringBody'],
+			[/[rR][fF]'''/, 'string.escape', '@fTripleStringBody'],
+			[/[fF][rR]?'/, 'string.escape', '@fStringBody'],
+			[/[rR][fF]'/, 'string.escape', '@fStringBody'],
 			[/'/, 'string.escape', '@stringBody'],
 			[/"$/, 'string.escape', '@popall'],
-			[/f"{1,3}/, 'string.escape', '@fDblStringBody'],
+			[/[fF][rR]?"""/, 'string.escape', '@fDblTripleStringBody'],
+			[/[rR][fF]"""/, 'string.escape', '@fDblTripleStringBody'],
+			[/[fF][rR]?"/, 'string.escape', '@fDblStringBody'],
+			[/[rR][fF]"/, 'string.escape', '@fDblStringBody'],
 			[/"/, 'string.escape', '@dblStringBody']
 		],
 		fStringBody: [
@@ -264,6 +270,14 @@ export const language = <languages.IMonarchLanguage>{
 			[/'/, 'string.escape', '@popall'],
 			[/\\$/, 'string']
 		],
+		fTripleStringBody: [
+			[/[^\\'\{\}]+/, 'string'],
+			[/\{[^\}':!=]+/, 'identifier', '@fStringDetail'],
+			[/\\./, 'string'],
+			[/'''/, 'string.escape', '@popall'],
+			[/'/, 'string'],
+			[/\\$/, 'string']
+		],
 		stringBody: [
 			[/[^\\']+$/, 'string', '@popall'],
 			[/[^\\']+/, 'string'],
@@ -279,6 +293,14 @@ export const language = <languages.IMonarchLanguage>{
 			[/"/, 'string.escape', '@popall'],
 			[/\\$/, 'string']
 		],
+		fDblTripleStringBody: [
+			[/[^\\"\{\}]+/, 'string'],
+			[/\{[^\}':!=]+/, 'identifier', '@fStringDetail'],
+			[/\\./, 'string'],
+			[/"""/, 'string.escape', '@popall'],
+			[/"/, 'string'],
+			[/\\$/, 'string']
+		],
 		dblStringBody: [
 			[/[^\\"]+$/, 'string', '@popall'],
 			[/[^\\"]+/, 'string'],