P18 phase 1: one console and Stop (IDE and embed, protocol v4)

CLAUDE.md

@@ -52,7 +52,7 @@ There is no unit test framework. The automated checks are `test:protocol` (plain
   - Values are shown through `_glpython_safe_repr`, which writes types as learners do (`int`, not `<class 'int'>`); the program's own output keeps Python's repr.
 
 Worker messages:
-- `run` → `result`/`error`
+- `run` → `result`/`error`; while it runs, `output` messages (`{id, text}`, `id` undefined for a program, the input's id for a REPL input) stream what was printed, at most 50 per 50 ms. The final message brings the whole output again.
 - `run-visual` → `trace-result` (`{trace, ast, output, graphics, error, errorMessage, truncated}`)
 - `repl` → `repl-result`
 - `run-visual-repl` (a doctest example) → `trace-result` with `rootPath`/`sources`, or `repl-result` if the input doesn't parse
@@ -68,7 +68,8 @@ Worker messages:
 - **Rendering always replays the full trace up to the current step's `step` number.** In substitution mode the scrubber moves through a filtered step list, so use list indices only for the scrubber, never as step numbers.
 - **Visualizer modes:** in `box` mode every call is a `Frame` box at its call site. In `substitution` mode (the default; prop `visualizerMode`, embed `?visualizer=`), a call with `shortForm` renders as `Frame` scope `'inline'`: its return expression with parameters substituted, in parentheses in operator context.
 - **Layout and scrolling:** nested boxes show their variables below their code (CSS). The scroll effect follows the active box horizontally. It sets `scrollLeft`/`scrollTop` on the visualizer view only; don't use `scrollIntoView`, which also scrolls the LiaScript page around the embed and moves the step buttons.
+- **Console and Stop:** output, REPL inputs, Tests reports and notes form one transcript (`ConsoleEntry` list after `output`). While Python is busy for more than `STOP_BUTTON_DELAY`, the run button is **Stop**: `stopPython` terminates the worker and calls `startWorker` again, so the REPL namespace is gone after a stop. The embed reports this to its parent (protocol version 4, `glpython:busy`/`glpython:stop`).
 - **UI strings** come in via the `t: CoreStrings` prop. `src/i18n.ts` is their single source: `coreStrings` holds German and English, and `resolveUiLocale` picks the language. The embed uses them directly; the glpython IDE imports them and adds only its shell strings. New strings have been added as *optional* `CoreStrings` keys with an English fallback, so older hosts keep compiling; add both languages to `coreStrings`. Python values, reprs and error messages are never translated.
 - **Embedded/reduced layouts:** the knobs are `compact`, `capabilities` (`WorkspaceCapabilities`, including `repl`) and `command` (`WorkspaceCommand`, an immutable `{id, type}` used by editor-free hosts to trigger run/visualize). Defaults must preserve the full-workspace behavior.
 
-**Embed protocol.** `src/embedProtocol.ts` defines the versioned message types and validators (`parseParentMessage`, `parseParentOrigin`, `GLPYTHON_EMBED_PROTOCOL_VERSION`, `GLPYTHON_MAX_SOURCE_LENGTH`), all re-exported from `src/index.ts`. The iframe (`src/embed/App.tsx`) requires an exact `parentOrigin` query param, sends `glpython:ready`/`glpython:resize`, and accepts `glpython:load`/`run`/`visualize`/`reset`. `run`/`visualize` carry the source snapshot so the parent remains the authoritative editor. Version 2 adds `files` + `mainFile` for programs of several files, version 3 adds `glpython:test` (doctests); the embed still accepts every earlier version and answers each parent in the version it last used, so older (e.g. cached) macros keep working. Modes: `eval` (with REPL), `turtle` (graphics layout), `visual` (visualizer-only, cannot exit). Reset remounts the workspace via a `key` generation counter, which also recreates the worker. Any protocol change should bump/handle the version and be covered in `scripts/check-embed-protocol.mjs`; also update `embed/demo.html` and the README.
+**Embed protocol.** `src/embedProtocol.ts` defines the versioned message types and validators (`parseParentMessage`, `parseParentOrigin`, `GLPYTHON_EMBED_PROTOCOL_VERSION`, `GLPYTHON_MAX_SOURCE_LENGTH`), all re-exported from `src/index.ts`. The iframe (`src/embed/App.tsx`) requires an exact `parentOrigin` query param, sends `glpython:ready`/`glpython:resize`, and accepts `glpython:load`/`run`/`visualize`/`reset`. `run`/`visualize` carry the source snapshot so the parent remains the authoritative editor. Version 2 adds `files` + `mainFile` for programs of several files, version 3 adds `glpython:test` (doctests); version 4 adds `glpython:stop` and `glpython:busy`; the embed still accepts every earlier version and answers each parent in the version it last used, so older (e.g. cached) macros keep working. Modes: `eval` (with REPL), `turtle` (graphics layout), `visual` (visualizer-only, cannot exit). Reset remounts the workspace via a `key` generation counter, which also recreates the worker. Any protocol change should bump/handle the version and be covered in `scripts/check-embed-protocol.mjs`; also update `embed/demo.html` and the README.

README.md

@@ -175,9 +175,25 @@ visualizer's error marking, worded by `errorHint` and labelled by
 In the visualizer, a call with the wrong arguments fails as in Python, with
 Python's own `TypeError`.
 
+### Console and Stop
+
+The console (`output`: «Konsole») is one chronological transcript, like Python
+in a terminal: what the program printed - shown while it runs, not only at the
+end - then every REPL input with its answer, every Tests report and every note,
+in the order they happened. Errors and their hints stand where they happened.
+Run and Reset clear it. It keeps the last 100,000 characters of a long output.
+
+While Python is busy for more than a moment (a program, a REPL input, Tests,
+a visualization), the run button becomes **Stop** (`stop`: «Stoppen»). Stopping
+ends Python's worker and starts a new one: the code stays, the console keeps
+what was printed and adds `stoppedNote`, and the REPL starts in an empty
+namespace (earlier entries can't be visualized anymore). Hosts can stop with
+the command `{ id, type: 'stop' }`, and learn when Python is busy through the
+`onBusyChange` prop.
+
 ### REPL
 
-Below the output panel, a `>>>` input line runs Python in the namespace of the
+Below the console, a `>>>` input line runs Python in the namespace of the
 last Run, so learners can call the file's functions directly. An expression
 shows its value (`None` too, greyed out); a statement such as `a = 5` shows
 nothing; a `def` runs but adds the hint `replDefinitionHint`; an error shows
@@ -276,7 +292,13 @@ files run as a black box. Version 3 adds `glpython:test` (same fields as
 `run`), which runs the doctests of that file. The embed still accepts every
 earlier version and answers every parent in the version that parent last used
 (version 1 until it hears otherwise), so older parents keep working.
-`glpython:ready` reports `capabilities.files` and `capabilities.tests`.
+Version 4 adds `glpython:stop`, which stops what Python is running by
+restarting it (the source stays), and `glpython:busy` (`busy: true|false`),
+which the embed sends to a version 4 parent when Python has been busy for more
+than a moment (a program, a REPL input, Tests, a visualization), so the
+parent's run button can become a stop button, as the workspace's own does.
+`glpython:ready` reports `capabilities.files`, `capabilities.tests` and
+`capabilities.stop`.
 
 ```ts
 iframe.contentWindow?.postMessage({

embed/demo.html

@@ -40,7 +40,7 @@
           type: `glpython:${command}`,
           version: GLPYTHON_EMBED_PROTOCOL_VERSION,
         }
-        if (command !== 'reset') {
+        if (command !== 'reset' && command !== 'stop') {
           message.source = sources[mode]
           message.mode = mode
         }
@@ -64,6 +64,13 @@
           events.dataset.inputAvailable = String(event.data.capabilities?.input === true)
           send('load')
         }
+        // Version 4: while Python is busy (e.g. "while True: pass" typed into
+        // the REPL), Run becomes Stop.
+        if (event.data?.type === 'glpython:busy') {
+          const runButton = document.querySelector('[data-command="run"], [data-command="stop"]')
+          runButton.dataset.command = event.data.busy ? 'stop' : 'run'
+          runButton.textContent = event.data.busy ? '■ Stop' : 'Run'
+        }
         if (event.data?.type === 'glpython:resize' && Number.isFinite(event.data.height)) {
           iframe.style.height = `${Math.max(400, event.data.height)}px`
         }

scripts/check-embed-protocol.mjs

@@ -80,10 +80,10 @@ assert.equal(parseParentMessage({
 }), null)
 
 // Version 1 (a single source) is still accepted, without files.
-assert.equal(GLPYTHON_EMBED_PROTOCOL_VERSION, 3)
+assert.equal(GLPYTHON_EMBED_PROTOCOL_VERSION, 4)
 assert.deepEqual(parseParentMessage({ type: 'glpython:run', version: 1, source: 'print(1)', mode: 'eval' }), { type: 'glpython:run', version: 1, source: 'print(1)', mode: 'eval' })
 assert.equal(parseParentMessage({ type: 'glpython:run', version: 1, source: 'x', files: [{ path: 'main.py', source: 'x' }], mainFile: 'main.py' }), null)
-assert.equal(parseParentMessage({ type: 'glpython:reset', version: 4 }), null)
+assert.equal(parseParentMessage({ type: 'glpython:reset', version: 5 }), null)
 
 // Version 2: a program of several files and the one to run.
 const program = {
@@ -116,6 +116,14 @@ assert.equal(parseParentMessage({ ...tests, version: 2 }), null)
 assert.equal(parseParentMessage({ type: 'glpython:test', version: 1, source: 'x' }), null)
 assert.deepEqual(parseParentMessage({ ...program, version: 3 }), { ...program, version: 3 })
 
+// Version 4: stopping what Python runs; not before version 4. Earlier
+// messages are accepted in version 4 too.
+assert.deepEqual(parseParentMessage({ type: 'glpython:stop', version: 4 }), { type: 'glpython:stop', version: 4 })
+assert.equal(parseParentMessage({ type: 'glpython:stop', version: 3 }), null)
+assert.equal(parseParentMessage({ type: 'glpython:stop', version: 1 }), null)
+assert.deepEqual(parseParentMessage({ ...tests, version: 4 }), { ...tests, version: 4 })
+assert.deepEqual(parseParentMessage({ type: 'glpython:reset', version: 4 }), { type: 'glpython:reset', version: 4 })
+
 const readyMessage = {
   type: 'glpython:ready',
   version: GLPYTHON_EMBED_PROTOCOL_VERSION,