From 6c534da7c5baf4862ac26ffb4f66804834d4fec5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Vogel?= <cedric.vogel@edubs.ch>
Date: Sun, 25 Oct 2026 23:26:35 +0100
Subject: [PATCH 1/2] =?UTF-8?q?=E2=96=B6=20Ausf=C3=BChren=20becomes=20?=
 =?UTF-8?q?=E2=96=A0=20Stoppen=20while=20Python=20is=20busy=20(P18)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Speaks protocol version 4 with embeds that understand it: the embed says
when Python is busy (glpython:busy), and the run button then sends
glpython:stop, which restarts Python; the code stays. The button keeps its
width, so the row doesn't move. With an older embed nothing changes.

The macro now accepts the embed's answers in every version up to 4 (it
answers in the version the macro last used), not only 1 and the newest,
and sends each embed the newest version both understand.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 README.md | 52 ++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 10 deletions(-)

diff --git a/README.md b/README.md
index 8d37f80..720b89e 100644
--- a/README.md
+++ b/README.md
@@ -36,7 +36,7 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
 
 <script run-once>
 (() => {
-  const protocolVersion = 3
+  const protocolVersion = 4
   const embedOrigin = "https://glpython-edu.github.io"
   const embedUrl = `${embedOrigin}/glpython-editor/index.html`
   const sessionId = "@0"
@@ -74,6 +74,7 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
   const strings = {
     de: {
       run: "Ausführen",
+      stop: "Stoppen",
       reset: "Zurücksetzen",
       visualize: "Visualisieren",
       tests: "Tests",
@@ -94,6 +95,7 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
     },
     en: {
       run: "Run",
+      stop: "Stop",
       reset: "Reset",
       visualize: "Visualize",
       tests: "Tests",
@@ -171,6 +173,12 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
   let inputAvailable = false
   let filesSupported = false
   let testsSupported = false
+  // Version 4: the embed can stop Python, and says while it is busy - then
+  // ▶ Run is ■ Stop.
+  let stopSupported = false
+  let pythonBusy = false
+  // The newest protocol version both understand.
+  const embedVersion = () => stopSupported ? protocolVersion : testsSupported ? 3 : filesSupported ? 2 : 1
   let runtimeReady = false
   let pendingRun = false
   // The code file chosen in the split button's menu; null runs the last one.
@@ -309,7 +317,7 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
     reportInputCapability(main.source)
     if (filesSupported) {
       // Version 3 ("glpython:test") only with embeds that understand it.
-      frame.contentWindow.postMessage({ type, version: testsSupported ? protocolVersion : 2, source: main.source, mode, files: program.files, mainFile: program.mainFile }, embedOrigin)
+      frame.contentWindow.postMessage({ type, version: embedVersion(), source: main.source, mode, files: program.files, mainFile: program.mainFile }, embedOrigin)
     } else {
       if (program.files.length > 1) showError(strings.filesUnsupported)
       frame.contentWindow.postMessage({ type, version: 1, source: main.source, mode }, embedOrigin)
@@ -318,8 +326,12 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
 
   const sendCommand = (type, fallbackSource) => {
     if (!frame?.contentWindow) return
+    if (type === "glpython:stop") {
+      if (stopSupported) frame.contentWindow.postMessage({ type, version: protocolVersion }, embedOrigin)
+      return
+    }
     if (type === "glpython:reset") {
-      frame.contentWindow.postMessage({ type, version: testsSupported ? protocolVersion : filesSupported ? 2 : 1 }, embedOrigin)
+      frame.contentWindow.postMessage({ type, version: embedVersion() }, embedOrigin)
       return
     }
     postProgram(type, fallbackSource)
@@ -338,14 +350,16 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
     if (!frame || event.origin !== embedOrigin || event.source !== frame.contentWindow) return
     const message = event.data
     // The embed answers in the version this macro last used (1 until it knows
-    // the embed understands version 2).
-    if (!message || (message.version !== 1 && message.version !== protocolVersion)) return
+    // what the embed understands, see embedVersion).
+    if (!message || ![1, 2, 3, 4].includes(message.version)) return
 
     if (message.type === "glpython:ready") {
       runtimeReady = true
       inputAvailable = message.capabilities?.input === true
       filesSupported = message.capabilities?.files === true
       testsSupported = message.capabilities?.tests === true
+      stopSupported = message.capabilities?.stop === true
+      pythonBusy = false
       frame.dataset.inputAvailable = String(inputAvailable)
       sendCommand(mode === "visual" ? "glpython:visualize" : "glpython:load")
       if (pendingRun) {
@@ -362,6 +376,9 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
       // The embed's height follows its content (the visualizer too, unless
       // "large" asks for 60% of the window).
       frame.style.height = `${Math.max(170, Math.min(message.height, 1200))}px`
+    } else if (message.type === "glpython:busy") {
+      pythonBusy = message.busy === true
+      attach()
     } else if (message.type === "glpython:error") {
       showError(message.message || strings.embedError)
     }
@@ -394,7 +411,9 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
     const menuButton = document.getElementById(`glpython-run-menu-${sessionId}`)
     const menu = document.getElementById(`glpython-run-list-${sessionId}`)
     if (!split || !runButton || !menuButton || !menu) return
-    runButton.onclick = runThroughLiaScript
+    // While Python is busy (only embeds of protocol version 4 say so), the same
+    // button stops it: Python restarts, the code stays.
+    runButton.onclick = pythonBusy ? () => sendCommand("glpython:stop") : runThroughLiaScript
     // The run button whenever "run" is on; its ▾ menu only for several files.
     const show = mode !== "visual" && hasFeature("run")
     setShown(split, show, "inline-flex")
@@ -402,10 +421,14 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
     const severalFiles = codeFiles.length > 1
     setShown(menuButton, severalFiles)
     split.classList.toggle("glp-run-split--menu", severalFiles)
-    const label = `▶ ${strings.run}`
-    if (runButton.textContent !== label) runButton.textContent = label
+    const label = pythonBusy ? `■ ${strings.stop}` : `▶ ${strings.run}`
+    if (runButton.textContent !== label) {
+      // ■ Stop keeps ▶ Run's width, so the buttons beside it don't move.
+      runButton.style.minWidth = pythonBusy ? `${runButton.offsetWidth}px` : ""
+      runButton.textContent = label
+    }
     const mainFile = codeFiles.length === 0 ? null : codeFiles.some((file) => file.path === chosenFile) ? chosenFile : codeFiles[codeFiles.length - 1].path
-    const title = severalFiles && mainFile ? strings.runFile(mainFile) : strings.run
+    const title = pythonBusy ? strings.stop : severalFiles && mainFile ? strings.runFile(mainFile) : strings.run
     if (runButton.title !== title) runButton.title = title
     if (!severalFiles) return
     if (menuButton.title !== strings.chooseFile) {
@@ -440,7 +463,10 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
   const attach = () => {
     const nextFrame = document.getElementById(`glpython-frame-${sessionId}`)
     if (!nextFrame) return
-    if (frame !== nextFrame) runtimeReady = false
+    if (frame !== nextFrame) {
+      runtimeReady = false
+      pythonBusy = false
+    }
     frame = nextFrame
     error = document.getElementById(`glpython-error-${sessionId}`)
     const controls = document.getElementById(`glpython-controls-${sessionId}`)
@@ -720,6 +746,12 @@ and the classes `glp-button` plus one per function (`glp-button--run`,
 has `glp-button--primary`, its ▾ menu `glp-button--run-menu`. The row has
 `glp-buttons`, so a course can restyle all of it with `@style`.
 
+While Python is busy (a program, a REPL input or Tests that run for more than
+a moment, e.g. `while True:`), ▶ Run becomes **■ Stop** («■ Stoppen») in the
+same place and width: it restarts Python, the code stays, and the console notes
+it. This needs an embed of protocol version 4; with an older embed ▶ Run stays
+as it was.
+
 The block has glpython's own look (the course design: white, light grey code
 areas, ink accent, the system's fonts) without any `@style`: ▶ Run is filled,
 the other buttons are outlined, and the block stays light in LiaScript's dark

From a3b03279c6d4474baab0e451508bb5d3578a1b87 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Vogel?= <cedric.vogel@edubs.ch>
Date: Sun, 25 Oct 2026 23:26:56 +0100
Subject: [PATCH 2/2] Keep the busy handler apart from the resize handler
 (merges with #17)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 README.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 720b89e..e61085c 100644
--- a/README.md
+++ b/README.md
@@ -372,13 +372,13 @@ comment:  Embed the glpython editor, execution visualizer, and turtle graphics
       }
       attach()
       send.lia("LIA: stop")
+    } else if (message.type === "glpython:busy") {
+      pythonBusy = message.busy === true
+      attach()
     } else if (message.type === "glpython:resize" && Number.isFinite(message.height)) {
       // The embed's height follows its content (the visualizer too, unless
       // "large" asks for 60% of the window).
       frame.style.height = `${Math.max(170, Math.min(message.height, 1200))}px`
-    } else if (message.type === "glpython:busy") {
-      pythonBusy = message.busy === true
-      attach()
     } else if (message.type === "glpython:error") {
       showError(message.message || strings.embedError)
     }