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fix(ssh): restore exitAlternateScreenBuffer to prevent character loss on session open #138

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fix(ssh): restore exitAlternateScreenBuffer to prevent character loss on session open #138

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22 changes: 12 additions & 10 deletions src/components/InteractiveSpawn.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import { spawn, ChildProcess } from "child_process";
import {
showCursor,
clearScreen,
exitAlternateScreenBuffer,
enterAlternateScreenBuffer,
} from "../utils/screen.js";
import { processUtils } from "../utils/processUtils.js";
Expand All @@ -24,14 +25,20 @@ interface InteractiveSpawnProps {
* This directly manipulates stdin to bypass Ink's input handling.
*/
function releaseTerminal(): void {
// Exit alternate screen buffer so the subprocess runs in the normal screen buffer.
// This prevents Ink's ongoing renders (which target the alt buffer) from
// interfering with the subprocess's terminal I/O, which was causing characters
// to be lost at the start of the session.
exitAlternateScreenBuffer();

// Pause stdin to stop Ink from reading input
process.stdin.pause();

// Disable raw mode so the subprocess can control terminal echo and line buffering
// SSH needs to set its own terminal modes
if (processUtils.stdin.isTTY && processUtils.stdin.setRawMode) {
processUtils.stdin.setRawMode(false);
}
// NOTE: We intentionally do NOT call setRawMode(false) here. Leaving the terminal
// in raw mode means characters typed during the subprocess connection setup remain
// immediately available in the kernel buffer (no canonical line-buffering). Calling
// setRawMode(false) would invoke tcsetattr(TCSAFLUSH) which discards pending input
// and switches to canonical mode where keystrokes are held until Enter is pressed.

// Reset terminal attributes (SGR reset) - clears any colors/styles Ink may have set
if (processUtils.stdout.isTTY) {
Expand All @@ -40,11 +47,6 @@ function releaseTerminal(): void {

// Show cursor - Ink may have hidden it, and subprocesses expect it to be visible
showCursor();

// Flush stdout to ensure all pending writes are complete before handoff
if (processUtils.stdout.isTTY) {
processUtils.stdout.write("");
}
}

/**
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