fix(coding-agent): keep Shift+Enter newline working where it sends a raw \n

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Fixed Shift+Enter no longer inserting a newline in terminals that send a literal `\n` (for example a Ghostty `shift+enter=text:\n` mapping): the byte decoded as `ctrl+j` and triggered the new edit-diff toggle instead of the editor newline.
 - Removed a system prompt paragraph referring to an async `bash()` kernel helper and managed jobs that do not exist in the runtime.
 - Changed RLM guidance to orchestrate independent workers in parallel, use available async shell helpers safely, end the turn instead of sleeping, polling, or blocking on long awaits, provide proactive outcome-focused progress updates from root agents, and use simplified technical English for user-facing prose.
 - Fixed new top-level daemon sessions inheriting an RLM child depth from the supervisor process.

packages/coding-agent/src/modes/interactive/components/custom-editor.ts

@@ -198,9 +198,11 @@ export class CustomEditor extends Editor {
 			// Fall through to editor handling for delete-char-forward when not empty
 		}
 
-		// Check all other app actions
+		// Check all other app actions. A raw "\n" is Shift+Enter's newline in some
+		// terminals, so it goes to the editor even though it decodes as ctrl+j.
 		for (const [action, handler] of this.actionHandlers) {
 			if (
+				data !== "\n" &&
 				action !== "app.input.clear" &&
 				action !== "app.exit" &&
 				(action !== "app.shortcuts" || this.getText().length === 0) &&

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -5900,7 +5900,8 @@ export class InteractiveMode {
 			this.toggleAgentMessageExpansion();
 			return;
 		}
-		if (this.keybindings.matches(data, "app.edits.expand")) {
+		// A raw "\n" is a newline for the editor, not ctrl+j.
+		if (data !== "\n" && this.keybindings.matches(data, "app.edits.expand")) {
 			this.toggleEditDiffExpansion();
 			return;
 		}

packages/coding-agent/test/custom-editor.test.ts

@@ -78,6 +78,30 @@ describe("CustomEditor", () => {
 		expect(editor.getText()).toBe("/");
 	});
 
+	it("inserts a newline for a raw \\n byte instead of firing the ctrl+j edit-diff action", () => {
+		const editor = new CustomEditor(fakeTui, editorTheme, new KeybindingsManager());
+		const toggleEditDiffs = vi.fn();
+		editor.onAction("app.edits.expand", toggleEditDiffs);
+
+		editor.handleInput("a");
+		editor.handleInput("\n");
+		editor.handleInput("b");
+
+		expect(toggleEditDiffs).not.toHaveBeenCalled();
+		expect(editor.getText()).toBe("a\nb");
+	});
+
+	it("still fires the edit-diff action for kitty CSI-u ctrl+j", () => {
+		const editor = new CustomEditor(fakeTui, editorTheme, new KeybindingsManager());
+		const toggleEditDiffs = vi.fn();
+		editor.onAction("app.edits.expand", toggleEditDiffs);
+
+		editor.handleInput("\x1b[106;5u");
+
+		expect(toggleEditDiffs).toHaveBeenCalledOnce();
+		expect(editor.getText()).toBe("");
+	});
+
 	it("routes Escape through its handler while dismissing autocomplete", async () => {
 		const editor = new CustomEditor(fakeTui, editorTheme, new KeybindingsManager());
 		const handler = vi.fn();