fix: remove trailing space padding from TUI chat lines

.changeset/fix-tui-copy-trailing-spaces.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix copied TUI chat lines ending with trailing spaces.

apps/kimi-code/test/tui/components/messages/assistant-message.test.ts

@@ -129,13 +129,23 @@ describe('AssistantMessageComponent', () => {
     expect(highlightSpy).toHaveBeenCalled();
   });
 
+  it('does not pad code block lines with trailing spaces', () => {
+    const component = new AssistantMessageComponent();
+    component.updateContent('```bash\nbash script.sh \\\n    --flag1 \\\n    --flag2\n```');
+
+    const lines = component.render(80).map(strip);
+    for (const line of lines) {
+      expect(line).toBe(line.trimEnd());
+    }
+  });
+
   it('marks the rendered zone with OSC 133 markers, once across cache hits', () => {
     const component = new AssistantMessageComponent();
     component.updateContent('hello');
 
     const lines = component.render(80);
     expect(lines[0]).toMatch(/^\u001B\]133;A\u0007/);
-    expect(lines[lines.length - 1]).toMatch(/^\u001B\]133;B\u0007\u001B\]133;C\u0007/);
+    expect(lines.at(-1)).toMatch(/^\u001B\]133;B\u0007\u001B\]133;C\u0007/);
 
     const cached = component.render(80);
     expect(cached[0]).toBe(lines[0]);

packages/pi-tui/AGENTS.md

@@ -14,6 +14,7 @@ Never overwrite this directory wholesale when syncing from upstream. Each of the
 6. **`src/components/markdown.ts` — `CjkBoundaryUrlTokenizer` autolink CJK boundary**: marked's GFM autolink accepts any non-space characters after the domain and its backpedal strips only ASCII trailing punctuation, so CJK/full-width punctuation right after a bare URL is absorbed into the link text and href (`.../pull/232（本地` renders as one anchor with a CJK target). The `CjkBoundaryUrlTokenizer` subclass (the tokenizer actually registered on the parser) cuts the match at the first CJK punctuation character before the ASCII backpedal; full-width parentheses follow GFM's ASCII-paren rule — balanced pairs stay in the URL (`.../wiki/中华人民共和国（1949年）`, punctuation inside them included), only unbalanced ones terminate the match. `StrictStrikethroughTokenizer` itself stays byte-identical to upstream. Guarding tests: the bare-URL CJK cases in the "Links" group in `test/markdown.test.ts`.
 7. **`src/components/editor.ts` — opt-in inline slash autocomplete (`inlineSlashTrigger`)**: when enabled, `/` after whitespace mid-input or at the start of a subsequent line auto-triggers autocomplete (`isAtInlineSlashTrigger`), and typing further token characters (letters, digits, `.`, `-`, `_`, `:`) inside that inline token re-triggers the request (`isInInlineSlashContext`) so the in-flight request from the bare `/` cannot go stale before the menu appears; `:` is required because external skill tokens are shaped `/skill:<name>`. Off by default — prose slashes (paths, fractions) keep upstream behavior. Guarding tests: the "Inline slash trigger" group in `test/editor.test.ts`.
 8. **`src/autocomplete.ts` / `src/components/select-list.ts` / `src/components/editor.ts` — `data` on autocomplete items + Enter non-submit for marked completions**: autocomplete items may carry an opaque `data` record; when the selected item's `data.inlineSkill` is set, confirming with Enter applies the completion without submitting the editor (ordinary completions keep upstream Enter-submits behavior). Guarding tests: "does not submit when confirming an inline-marked completion with Enter" and "still submits when confirming an unmarked slash completion with Enter" in `test/editor.test.ts`.
+9. **`src/components/text.ts` / `src/components/markdown.ts` — no trailing space padding without background**: when no `bgFn` is applied, lines keep their margins but are not padded to full width, so copied chat lines carry no trailing spaces and shell backslash line continuations survive copy-paste. Padding is unnecessary for display because the main-screen and alt-screen renderers already clear each line with `\x1b[2K` before drawing. Guarding tests: the no-trailing-space cases in `test/tui-render.test.ts`, `test/markdown.test.ts`, and `apps/kimi-code/test/tui/components/messages/assistant-message.test.ts`.
 
 ## Acceptance after syncing from upstream
 

packages/pi-tui/src/components/markdown.ts

@@ -434,10 +434,10 @@ export class Markdown implements Component {
 			if (bgFn) {
 				contentLines.push(applyBackgroundToLine(lineWithMargins, width, bgFn));
 			} else {
-				// No background - just pad to width
-				const visibleLen = visibleWidth(lineWithMargins);
-				const paddingNeeded = Math.max(0, width - visibleLen);
-				contentLines.push(lineWithMargins + " ".repeat(paddingNeeded));
+				// No background - keep margins but do not pad to width. Padding
+				// would fill copied text with trailing spaces and break tokens
+				// (e.g. shell backslash line continuations).
+				contentLines.push(lineWithMargins);
 			}
 		}
 

packages/pi-tui/src/components/text.ts

@@ -1,5 +1,5 @@
 import type { Component } from "../tui.ts";
-import { applyBackgroundToLine, visibleWidth, wrapTextWithAnsi } from "../utils.ts";
+import { applyBackgroundToLine, wrapTextWithAnsi } from "../utils.ts";
 
 /**
  * Text component - displays multi-line text with word wrapping
@@ -79,10 +79,10 @@ export class Text implements Component {
 			if (this.customBgFn) {
 				contentLines.push(applyBackgroundToLine(lineWithMargins, width, this.customBgFn));
 			} else {
-				// No background - just pad to width with spaces
-				const visibleLen = visibleWidth(lineWithMargins);
-				const paddingNeeded = Math.max(0, width - visibleLen);
-				contentLines.push(lineWithMargins + " ".repeat(paddingNeeded));
+				// No background - keep margins but do not pad to width. Padding
+				// would fill copied text with trailing spaces and break tokens
+				// (e.g. shell backslash line continuations).
+				contentLines.push(lineWithMargins);
 			}
 		}
 

packages/pi-tui/test/markdown.test.ts

@@ -1785,3 +1785,24 @@ describe("Markdown negative width safety", () => {
 		assert.doesNotThrow(() => markdown.render(-1));
 	});
 });
+
+describe("Markdown copy-friendly rendering", () => {
+	it("does not pad code block lines with trailing spaces", () => {
+		const markdown = new Markdown(
+			"```bash\nbash script.sh \\\n    --flag1 \\\n    --flag2\n```",
+			0,
+			0,
+			defaultMarkdownTheme,
+		);
+		const lines = markdown.render(80).map((line) => stripAnsi(line));
+		const codeLines = lines.filter((line) => line.startsWith("  "));
+		assert.ok(codeLines.length >= 3, "should render code lines");
+		for (const line of codeLines) {
+			assert.strictEqual(
+				line,
+				line.trimEnd(),
+				`line should not have trailing spaces: ${JSON.stringify(line)}`,
+			);
+		}
+	});
+});

packages/pi-tui/test/tui-render.test.ts

@@ -895,6 +895,22 @@ describe("Text negative width safety", () => {
 	});
 });
 
+describe("Text copy-friendly rendering", () => {
+	it("does not fill short lines with trailing spaces", () => {
+		const text = new Text("hello", 0, 0);
+		const lines = text.render(80);
+		assert.strictEqual(lines.length, 1);
+		assert.strictEqual(lines[0], "hello");
+	});
+
+	it("keeps requested margins without filling the remaining width", () => {
+		const text = new Text("hello", 2, 0);
+		const lines = text.render(80);
+		assert.strictEqual(lines.length, 1);
+		assert.strictEqual(lines[0], "  hello  ");
+	});
+});
+
 describe("TUI steady-frame processed-line reuse", () => {
 	it("writes only the changed line when one component updates in a long transcript", async () => {
 		const terminal = new LoggingVirtualTerminal(40, 10);