diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index 408d9d9ee..04d091efa 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed terminal width accounting for Indic conjunct grapheme clusters ([#6124](https://github.com/earendil-works/pi/issues/6124) by [@petrroll](https://github.com/petrroll)).
+
 ### Added
 
 - Added interface-compatible main-screen and alternate-screen TUI renderers with application-owned scrolling ([#7304](https://github.com/earendil-works/pi/issues/7304)).
diff --git a/packages/tui/src/utils.ts b/packages/tui/src/utils.ts
index 29b339632..a3cc7fc6a 100644
--- a/packages/tui/src/utils.ts
+++ b/packages/tui/src/utils.ts
@@ -39,6 +39,12 @@ function couldBeEmoji(segment: string): boolean {
 // Regexes for character classification (same as string-width library)
 const zeroWidthRegex = /^(?:\p{Default_Ignorable_Code_Point}|\p{Control}|\p{Mark}|\p{Surrogate})+$/v;
 const leadingNonPrintingRegex = /^[\p{Default_Ignorable_Code_Point}\p{Control}\p{Format}\p{Mark}\p{Surrogate}]+/v;
+const nonPrintingCharRegex = /^(?:\p{Default_Ignorable_Code_Point}|\p{Control}|\p{Format}|\p{Mark}|\p{Surrogate})$/v;
+const markCharRegex = /^\p{Mark}$/v;
+// Marks that terminals allocate cells for when attached to a base character.
+// This includes Unicode spacing marks and non-spacing exceptions in legacy wcwidth tables.
+const terminalSpacingMarkRegex =
+	/^(?:[\p{Spacing_Mark}--[\u1734\u302E\u302F]]|[\u065F\u0F7F\u102B\u102C\u1031\u1033-\u1035\u1038\u103A-\u103E])+$/v;
 const rgiEmojiRegex = /^\p{RGI_Emoji}$/v;
 
 // Cache for non-ASCII strings
@@ -169,6 +175,11 @@ function graphemeWidth(segment: string): number {
 		return 3;
 	}
 
+	// Some marks occupy cells even without a base character.
+	if (terminalSpacingMarkRegex.test(segment)) {
+		return [...segment].length;
+	}
+
 	// Zero-width clusters
 	if (zeroWidthRegex.test(segment)) {
 		return 0;
@@ -195,15 +206,27 @@ function graphemeWidth(segment: string): number {
 
 	let width = eastAsianWidth(cp);
 
-	// Trailing halfwidth/fullwidth forms and AM vowels that segment with a base.
-	if (segment.length > 1) {
-		for (const char of segment.slice(1)) {
+	// Intl.Segmenter can group multiple terminal-spacing code points into one
+	// grapheme. Count trailing visible code points that terminals may allocate
+	// cells for: Indic consonants after marks, halfwidth/fullwidth forms, and
+	// Thai/Lao AM vowels.
+	let followsMark = false;
+	const chars = [...base];
+	for (const char of chars.slice(1)) {
+		if (terminalSpacingMarkRegex.test(char)) {
+			width += 1;
+			followsMark = false;
+		} else if (markCharRegex.test(char)) {
+			followsMark = true;
+		} else if (!nonPrintingCharRegex.test(char)) {
 			const c = char.codePointAt(0)!;
-			if (c >= 0xff00 && c <= 0xffef) {
+			if (followsMark || (c >= 0xff00 && c <= 0xffef)) {
+				// halfwidth + fullwidth forms
 				width += eastAsianWidth(c);
 			} else if (c === 0x0e33 || c === 0x0eb3) {
 				width += 1;
 			}
+			followsMark = false;
 		}
 	}
 
diff --git a/packages/tui/test/truncate-to-width.test.ts b/packages/tui/test/truncate-to-width.test.ts
index 321ba8983..31f80a379 100644
--- a/packages/tui/test/truncate-to-width.test.ts
+++ b/packages/tui/test/truncate-to-width.test.ts
@@ -60,6 +60,49 @@ describe("visibleWidth", () => {
 		assert.strictEqual(visibleWidth("\t\x1b[31m界\x1b[0m"), 5);
 	});
 
+	it("counts Indic conjunct spacing code points within grapheme clusters", () => {
+		assert.strictEqual(visibleWidth("र्क"), 2);
+		assert.strictEqual(visibleWidth("नेटवर्क"), 5);
+		assert.strictEqual(visibleWidth("सर्वाधिकार सुरक्षित। ऑर्डर पर क्लिक करें"), 33);
+		assert.strictEqual(visibleWidth("র্ক"), 2);
+		assert.strictEqual(visibleWidth("ર્ક"), 2);
+		assert.strictEqual(visibleWidth("ର୍କ"), 2);
+		assert.strictEqual(visibleWidth("ర్క"), 2);
+		assert.strictEqual(visibleWidth("ര്‍ക"), 2);
+	});
+
+	it("keeps ordinary combining marks zero-width", () => {
+		assert.strictEqual(visibleWidth("e\u0301"), 1);
+		assert.strictEqual(visibleWidth("čřžůú"), 5);
+		assert.strictEqual(visibleWidth("שָׁ"), 1);
+		assert.strictEqual(visibleWidth("بّ"), 1);
+		assert.strictEqual(visibleWidth("རྐ"), 1);
+		assert.strictEqual(visibleWidth("ᜠ᜴"), 1);
+		assert.strictEqual(visibleWidth("가〮"), 2);
+		assert.strictEqual(visibleWidth("가〯"), 2);
+	});
+
+	it("keeps CJK and Japanese width accounting unchanged", () => {
+		assert.strictEqual(visibleWidth("网络"), 4);
+		assert.strictEqual(visibleWidth("ネットワーク"), 12);
+		assert.strictEqual(visibleWidth("が"), 2);
+		assert.strictEqual(visibleWidth("か\u3099"), 2);
+	});
+
+	it("counts Myanmar marks that terminals allocate cells for", () => {
+		assert.strictEqual(visibleWidth("ကာ"), 2);
+		assert.strictEqual(visibleWidth("ကေ"), 2);
+		assert.strictEqual(visibleWidth("က်"), 2);
+		assert.strictEqual(visibleWidth("ကျ"), 2);
+		assert.strictEqual(visibleWidth("ကြ"), 2);
+		assert.strictEqual(visibleWidth("ကဳ"), 2);
+		assert.strictEqual(visibleWidth("ကဴ"), 2);
+		assert.strictEqual(visibleWidth("ကဵ"), 2);
+		assert.strictEqual(visibleWidth("ကး"), 2);
+		assert.strictEqual(visibleWidth("ကို"), 1);
+		assert.strictEqual(visibleWidth("က္"), 1);
+	});
+
 	it("keeps Thai and Lao AM clusters at their normal cell width", () => {
 		assert.strictEqual(visibleWidth("ำ"), 1);
 		assert.strictEqual(visibleWidth("ຳ"), 1);