From 3c0f5623dfab3f308a891491260edcb376827671 Mon Sep 17 00:00:00 2001
From: dormouse-bot <287024035+dormouse-bot@users.noreply.github.com>
Date: Sat, 11 Jul 2026 08:22:30 +0000
Subject: [PATCH] fix(website): route trailing bytes to a program launched
 mid-chunk in tutorial shell
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

TutorialShell.handleInput only checked activeProgram at the top of the
method, so when a single input chunk both launched an interactive program
(via a trailing \r) and carried the program's first keystroke — as a paste
of "cmd\rinput" would — the leftover bytes were parsed as shell line-editor
input instead of being forwarded to the just-started program.

Forward any bytes remaining after a program launch to that program and stop
parsing the chunk. Adds a regression test that fails without the fix.
---
 website/src/lib/tutorial-shell.test.ts | 16 ++++++++++++++++
 website/src/lib/tutorial-shell.ts      |  8 ++++++++
 2 files changed, 24 insertions(+)

diff --git a/website/src/lib/tutorial-shell.test.ts b/website/src/lib/tutorial-shell.test.ts
index 3b22ed88..0e81c050 100644
--- a/website/src/lib/tutorial-shell.test.ts
+++ b/website/src/lib/tutorial-shell.test.ts
@@ -45,6 +45,22 @@ describe("TutorialShell program dispatch", () => {
     expect(output.join("")).toContain("$ ");
   });
 
+  it("forwards trailing bytes to a program launched within the same chunk", () => {
+    const { program, shell, startProgram } = createHarness();
+
+    // A single chunk (e.g. a paste) both launches the program and carries the
+    // first keystroke for it. The trailing `q` must reach the program, not the
+    // shell line editor.
+    shell.handleInput("ascii-splash --no-mouse\rq");
+
+    expect(startProgram).toHaveBeenCalledWith(
+      "ascii-splash",
+      ["--no-mouse"],
+      expect.any(Function),
+    );
+    expect(program.handleInput).toHaveBeenCalledWith("q");
+  });
+
   it("disposes the active program with the shell", () => {
     const { program, shell } = createHarness();
 
diff --git a/website/src/lib/tutorial-shell.ts b/website/src/lib/tutorial-shell.ts
index 8caa1fec..cb1efa97 100644
--- a/website/src/lib/tutorial-shell.ts
+++ b/website/src/lib/tutorial-shell.ts
@@ -101,6 +101,14 @@ export class TutorialShell {
         this.lineBuffer = '';
         this.historyIndex = null;
         this.historyDraft = '';
+        // `processCommand` may have launched an interactive program. Any bytes
+        // left in this chunk (e.g. a paste of `cmd\rinput`) belong to that
+        // program, not the shell line editor — forward them and stop parsing.
+        if (this.activeProgram) {
+          const rest = data.slice(index + 1);
+          if (rest) this.activeProgram.handleInput(rest);
+          return;
+        }
       } else if (ch === '\x7f' || ch === '\b') {
         if (this.lineBuffer.length > 0) {
           this.lineBuffer = this.lineBuffer.slice(0, -1);