Fix Linux clipboard copy by adding OSC52 fallback

apps/cli/src/tui/clipboard.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, test } from 'bun:test';
+
+import { getOsc52Sequence, tryOsc52Copy } from './clipboard.ts';
+
+describe('clipboard OSC52 fallback', () => {
+	test('builds a valid OSC52 sequence', () => {
+		expect(getOsc52Sequence('hello')).toBe('\u001b]52;c;aGVsbG8=\u0007');
+	});
+
+	test('does not copy when stdout is not TTY', () => {
+		const writes: string[] = [];
+		const ok = tryOsc52Copy('hello', {
+			isTTY: false,
+			term: 'xterm-256color',
+			write: (value) => writes.push(value)
+		});
+		expect(ok).toBe(false);
+		expect(writes).toHaveLength(0);
+	});
+
+	test('does not copy on dumb terminal', () => {
+		const writes: string[] = [];
+		const ok = tryOsc52Copy('hello', {
+			isTTY: true,
+			term: 'dumb',
+			write: (value) => writes.push(value)
+		});
+		expect(ok).toBe(false);
+		expect(writes).toHaveLength(0);
+	});
+
+	test('writes OSC52 sequence on compatible terminal', () => {
+		const writes: string[] = [];
+		const ok = tryOsc52Copy('hello', {
+			isTTY: true,
+			term: 'xterm-256color',
+			write: (value) => writes.push(value)
+		});
+		expect(ok).toBe(true);
+		expect(writes).toEqual(['\u001b]52;c;aGVsbG8=\u0007']);
+	});
+});

apps/cli/src/tui/clipboard.ts

@@ -18,6 +18,35 @@ const isWayland = () => {
 	return !!process.env.WAYLAND_DISPLAY;
 };
 
+export const getOsc52Sequence = (text: string) => {
+	const encoded = Buffer.from(text, 'utf8').toString('base64');
+	return `\u001b]52;c;${encoded}\u0007`;
+};
+
+export const tryOsc52Copy = (
+	text: string,
+	options: {
+		isTTY?: boolean;
+		term?: string;
+		write?: (value: string) => unknown;
+	} = {}
+) => {
+	const isTTY = options.isTTY ?? process.stdout.isTTY;
+	const term = options.term ?? process.env.TERM;
+	const write = options.write ?? ((value: string) => process.stdout.write(value));
+
+	if (!isTTY) return false;
+	if (term === 'dumb') return false;
+
+	try {
+		// OSC52 allows terminals to copy text to the system clipboard without external binaries.
+		write(getOsc52Sequence(text));
+		return true;
+	} catch {
+		return false;
+	}
+};
+
 export async function copyToClipboard(text: string) {
 	const platform = process.platform;
 
@@ -58,11 +87,16 @@ export async function copyToClipboard(text: string) {
 
 		// Try xclip first, fall back to xsel
 		const xclipResult = await runClipboard(['xclip', '-selection', 'clipboard']);
-		if (!xclipResult) {
-			const xselResult = await runClipboard(['xsel', '--clipboard', '--input']);
-			if (!xselResult) {
-				throw new Error('Failed to copy to clipboard: no compatible clipboard command succeeded.');
-			}
+		if (xclipResult) return;
+
+		const xselResult = await runClipboard(['xsel', '--clipboard', '--input']);
+		if (xselResult) return;
+
+		const osc52Result = tryOsc52Copy(text);
+		if (!osc52Result) {
+			throw new Error(
+				'Failed to copy to clipboard: no compatible clipboard command succeeded and terminal OSC52 fallback is unavailable.'
+			);
 		}
 	}
 }

apps/cli/src/tui/context/messages-context.tsx

@@ -472,7 +472,12 @@ export const MessagesProvider = (props: { children: ReactNode }) => {
 			getAssistantMessageText(assistantMessage)
 		].join('\n');
 		try {
-			await runCliEffect(Effect.tryPromise(() => copyToClipboard(payload)));
+			await runCliEffect(
+				Effect.tryPromise({
+					try: () => copyToClipboard(payload),
+					catch: (error) => (error instanceof Error ? error : new Error(String(error)))
+				})
+			);
 		} catch (error) {
 			addMessage({ role: 'system', content: `Error: ${formatError(error)}` });
 			return;
@@ -493,7 +498,12 @@ export const MessagesProvider = (props: { children: ReactNode }) => {
 		}
 
 		try {
-			await runCliEffect(Effect.tryPromise(() => copyToClipboard(parts.join('\n\n'))));
+			await runCliEffect(
+				Effect.tryPromise({
+					try: () => copyToClipboard(parts.join('\n\n')),
+					catch: (error) => (error instanceof Error ? error : new Error(String(error)))
+				})
+			);
 		} catch (error) {
 			addMessage({ role: 'system', content: `Error: ${formatError(error)}` });
 			return;

apps/cli/src/tui/services.ts

@@ -115,21 +115,23 @@ export const services = {
 				const chunkOrder: string[] = [];
 				let doneEvent: Extract<BtcaStreamEvent, { type: 'done' }> | undefined;
 				try {
-					yield* Effect.tryPromise(() =>
-						(async () => {
-							for await (const event of parseSSEStream(response)) {
-								if (signal.aborted) break;
-								if (event.type === 'error') {
-									throw new Error(formatTuiStreamError(event));
+					yield* Effect.tryPromise({
+						try: () =>
+							(async () => {
+								for await (const event of parseSSEStream(response)) {
+									if (signal.aborted) break;
+									if (event.type === 'error') {
+										throw new Error(formatTuiStreamError(event));
+									}
+									if (event.type === 'done') {
+										doneEvent = event;
+										continue;
+									}
+									processStreamEvent(event, chunksById, chunkOrder, onChunkUpdate);
 								}
-								if (event.type === 'done') {
-									doneEvent = event;
-									continue;
-								}
-								processStreamEvent(event, chunksById, chunkOrder, onChunkUpdate);
-							}
-						})()
-					);
+							})(),
+						catch: (e) => (e instanceof Error ? e : new Error(String(e)))
+					});
 				} catch (error) {
 					if (!(error instanceof Error && error.name === 'AbortError')) {
 						return yield* Effect.fail(error);
@@ -152,12 +154,14 @@ export const services = {
 				if (!currentAbortController) return;
 				currentAbortController.abort();
 				currentAbortController = null;
-				yield* Effect.tryPromise(() =>
-					trackTelemetryEvent({
-						event: 'cli_stream_cancelled',
-						properties: { command: 'btca', mode: 'tui' }
-					})
-				);
+				yield* Effect.tryPromise({
+					try: () =>
+						trackTelemetryEvent({
+							event: 'cli_stream_cancelled',
+							properties: { command: 'btca', mode: 'tui' }
+						}),
+					catch: (e) => (e instanceof Error ? e : new Error(String(e)))
+				});
 			})
 		);
 	},

apps/docs/btca.spec.md

@@ -185,6 +185,13 @@ REPL supports `@resource` mentions.
 - `/copy` — copy the latest user question and assistant response
 - `/copy-all` — copy the full thread (all user and assistant messages)
 
+Clipboard behavior on Linux:
+
+- On WSL, btca first tries Windows clipboard via `clip.exe` (including Windows path fallback).
+- It then tries `wl-copy` (Wayland), then `xclip`, then `xsel`.
+- If these binaries are unavailable, btca falls back to terminal OSC52 clipboard copy.
+- OSC52 support depends on the terminal emulator and session configuration.
+
 **TUI keyboard shortcuts**:
 
 - `Enter` — send message

apps/docs/guides/cli-reference.mdx

@@ -41,6 +41,13 @@ TUI command palette (`/`):
 - `/copy` copies the latest user question and assistant response.
 - `/copy-all` copies the full thread (all user and assistant messages).
 
+Clipboard behavior on Linux:
+
+- On WSL, btca first tries Windows clipboard via `clip.exe` (including Windows path fallback).
+- It then tries `wl-copy` (Wayland), then `xclip`, then `xsel`.
+- If those tools are not installed, btca falls back to terminal OSC52 clipboard copy.
+- OSC52 support depends on your terminal emulator and SSH/session settings.
+
 TUI keyboard shortcuts:
 
 - `Enter` sends message.