diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index 2255c103..7c18f034 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed editor paste registry corruption when deleting paste markers: undo now restores the paste registry together with the text, and marker renumbering shifts registry entries in ascending id order, so submitted prompts no longer contain literal `[paste #N ...]` markers or the wrong paste's content ([#6844](https://github.com/earendil-works/pi/issues/6844)).
+
 ## [0.80.10] - 2026-07-16
 
 ## [0.80.9] - 2026-07-16
diff --git a/packages/tui/src/components/editor.ts b/packages/tui/src/components/editor.ts
index 3b55dc55..706324c7 100644
--- a/packages/tui/src/components/editor.ts
+++ b/packages/tui/src/components/editor.ts
@@ -212,6 +212,13 @@ interface EditorState {
 	cursorCol: number;
 }
 
+/** Undo snapshot: editor text state plus the paste registry. */
+interface EditorSnapshot {
+	state: EditorState;
+	pastes: Map<number, string>;
+	pasteCounter: number;
+}
+
 interface LayoutLine {
 	text: string;
 	hasCursor: boolean;
@@ -318,7 +325,7 @@ export class Editor implements Component, Focusable {
 	private snappedFromCursorCol: number | null = null;
 
 	// Undo support
-	private undoStack = new UndoStack<EditorState>();
+	private undoStack = new UndoStack<EditorSnapshot>();
 
 	public onSubmit?: (text: string) => void;
 	public onChange?: (text: string) => void;
@@ -999,13 +1006,13 @@ export class Editor implements Component, Focusable {
 		this.cancelAutocomplete();
 		this.lastAction = null;
 		this.exitHistoryBrowsing();
-		this.pastes.clear();
-		this.pasteCounter = 0;
 		const normalized = this.normalizeText(text);
 		// Push undo snapshot if content differs (makes programmatic changes undoable)
 		if (this.getText() !== normalized) {
 			this.pushUndoSnapshot();
 		}
+		this.pastes.clear();
+		this.pasteCounter = 0;
 		this.setTextInternal(normalized);
 	}
 
@@ -1284,17 +1291,21 @@ export class Editor implements Component, Focusable {
 				this.pastes.delete(targetId);
 				this.pasteCounter--;
 
-				// We got to update id of markers which are greater than the removed one
+				// Shift registry entries down in ascending id order, independent
+				// of marker order in the text ([paste #3] becomes [paste #2] when
+				// [paste #1] is removed).
+				const higherIds = [...this.pastes.keys()].filter((id) => id > targetId).sort((a, b) => a - b);
+				for (const id of higherIds) {
+					this.pastes.set(id - 1, this.pastes.get(id)!);
+					this.pastes.delete(id);
+				}
+
+				// Renumber markers with ids greater than the removed one.
 				this.state.lines = this.state.lines.map((line) =>
 					line.replace(PASTE_MARKER_REGEX, (fullMatch, idGroup, suffixGroup) => {
 						const x = Number(idGroup);
 						if (x <= targetId) return fullMatch;
-
-						// [paste #3] become [paste #2] if we remove [paste #1]
-						const newText = `[paste #${x - 1}${suffixGroup}]`;
-						this.pastes.set(x - 1, this.pastes.get(x) ?? newText);
-						this.pastes.delete(x);
-						return newText;
+						return `[paste #${x - 1}${suffixGroup}]`;
 					}),
 				);
 			}
@@ -1994,14 +2005,16 @@ export class Editor implements Component, Focusable {
 	}
 
 	private pushUndoSnapshot(): void {
-		this.undoStack.push(this.state);
+		this.undoStack.push({ state: this.state, pastes: this.pastes, pasteCounter: this.pasteCounter });
 	}
 
 	private undo(): void {
 		this.exitHistoryBrowsing();
 		const snapshot = this.undoStack.pop();
 		if (!snapshot) return;
-		Object.assign(this.state, snapshot);
+		Object.assign(this.state, snapshot.state);
+		this.pastes = snapshot.pastes;
+		this.pasteCounter = snapshot.pasteCounter;
 		this.lastAction = null;
 		this.preferredVisualCol = null;
 		if (this.onChange) {
diff --git a/packages/tui/test/editor.test.ts b/packages/tui/test/editor.test.ts
index 0f33370e..d2c278d7 100644
--- a/packages/tui/test/editor.test.ts
+++ b/packages/tui/test/editor.test.ts
@@ -3553,6 +3553,11 @@ describe("Editor component", () => {
 			return editor.getText();
 		}
 
+		/** Helper: 12-line paste content with a distinguishing tag */
+		function bigPaste(tag: string): string {
+			return Array.from({ length: 12 }, (_, i) => `${tag}${i}`).join("\n");
+		}
+
 		it("creates a paste marker for large pastes", () => {
 			const editor = new Editor(createTestTUI(), defaultEditorTheme);
 			const text = pasteWithMarker(editor);
@@ -3690,6 +3695,76 @@ describe("Editor component", () => {
 			assert.strictEqual(editor.getText(), textBefore);
 		});
 
+		it("undo after paste marker deletion restores the paste registry", () => {
+			const editor = new Editor(createTestTUI(), defaultEditorTheme);
+			let submitted = "";
+			editor.onSubmit = (t) => {
+				submitted = t;
+			};
+
+			const paste = bigPaste("alpha");
+			editor.handleInput(`\x1b[200~${paste}\x1b[201~`);
+			editor.handleInput("\x7f"); // delete the marker
+			editor.handleInput("\x1b[45;5u"); // undo: restores marker text and registry
+			editor.handleInput("\r");
+			assert.strictEqual(submitted, paste);
+		});
+
+		it("undo after deleting the first of two paste markers restores both registry entries", () => {
+			const editor = new Editor(createTestTUI(), defaultEditorTheme);
+			let submitted = "";
+			editor.onSubmit = (t) => {
+				submitted = t;
+			};
+
+			const pasteA = bigPaste("alpha");
+			const pasteB = bigPaste("beta");
+			editor.handleInput(`\x1b[200~${pasteA}\x1b[201~`); // #1 = A
+			editor.handleInput(`\x1b[200~${pasteB}\x1b[201~`); // #2 = B, cursor at end
+			editor.handleInput("\x01"); // Ctrl+A
+			editor.handleInput("\x1b[C"); // right over marker #1
+			editor.handleInput("\x7f"); // delete marker #1, renumbers #2 -> #1
+			editor.handleInput("\x1b[45;5u"); // undo
+			editor.handleInput("\r");
+			assert.strictEqual(submitted, pasteA + pasteB);
+		});
+
+		it("renumbers the paste registry in ascending id order when markers are out of order in text", () => {
+			const editor = new Editor(createTestTUI(), defaultEditorTheme);
+			let submitted = "";
+			editor.onSubmit = (t) => {
+				submitted = t;
+			};
+
+			const pasteA = bigPaste("alpha");
+			const pasteB = bigPaste("beta");
+			const pasteC = bigPaste("gamma");
+			editor.handleInput(`\x1b[200~${pasteA}\x1b[201~`); // #1 = A
+			editor.handleInput("\x01"); // Ctrl+A
+			editor.handleInput(`\x1b[200~${pasteB}\x1b[201~`); // #2 = B, text: [#2][#1]
+			editor.handleInput("\x01"); // Ctrl+A
+			editor.handleInput(`\x1b[200~${pasteC}\x1b[201~`); // #3 = C, text: [#3][#2][#1]
+			editor.handleInput("\x05"); // Ctrl+E
+			editor.handleInput("\x7f"); // delete marker #1, renumber #3 -> #2 and #2 -> #1
+			editor.handleInput("\r");
+			assert.strictEqual(submitted, pasteC + pasteB);
+		});
+
+		it("undo after setText restores paste markers and registry", () => {
+			const editor = new Editor(createTestTUI(), defaultEditorTheme);
+			let submitted = "";
+			editor.onSubmit = (t) => {
+				submitted = t;
+			};
+
+			const paste = bigPaste("alpha");
+			editor.handleInput(`\x1b[200~${paste}\x1b[201~`);
+			editor.setText("replacement");
+			editor.handleInput("\x1b[45;5u"); // undo
+			editor.handleInput("\r");
+			assert.strictEqual(submitted, paste);
+		});
+
 		it("handles multiple paste markers in same line", () => {
 			const editor = new Editor(createTestTUI(), defaultEditorTheme);
 			pasteWithMarker(editor);