Landmark demo — a minimal IDE in Nil-Python (import tk)

• Type: feature / demo (Track E — app built with pxx; Track B file-ownership, feature-demo-* auto-tags E). Build with the compiler, never rebuild it.
• Status: backlog (blocked on the tk surface + NilPy loop-control)
• Opened: 2026-07-17, from the "landmark demo" design discussion.
• Related: [[feature-nilpy-tk-binding]] (the GUI substrate), [[project_eliah_ilja_ide]] (the Pascal IDE — the boilerplate weight this demo deliberately undercuts).

The thesis

Minimal code, maximum functionality. A full-enough editor/IDE in a few hundred lines of Nil-Python, because import tk pushes all widget/layout/event work into mature Tcl/Tk. This is ir-as-substrate applied to apps: keep the app thin, lean on a proven external lib. The contrast with Eliah/Ilja (Pascal/LCL: class hierarchy + RTTI streaming + LFM + event objects, hundreds of lines before "hello window") is the point — same functionality, an order of magnitude less code.

Shape (all TkEval command strings + NilPy)

• Editor — Tk text widget (text .ed -wrap none; .ed insert, .ed get).
• Open / Save — NilPy file I/O (already works) + Tk tk_getOpenFile/tk_getSaveFile.
• Run button — dogfood. Spawn pxx on the buffer, capture stdout into an output pane. A pxx-compiled IDE that compiles pxx: self-referential landmark.
• Syntax highlight — Tk text tags (.ed tag add kw ...; .ed tag configure kw -foreground blue).
• Event loop — the proven poll model: widgets write Tcl vars, NilPy polls via TkEval("update"); no C callbacks. (Cleaner once [[feature-nilpy-break-continue]] lands — today it needs flag-variable loops.)

Acceptance

• A NilPy program (examples/tk/ide.npy) opens an editor window, loads/saves a file, and runs the current buffer through pxx with output shown — under xvfb for a headless smoke, interactively on a real display.
• Line count stays small enough to be the flex (target: the core IDE well under ~400 lines of NilPy).
• Build with $(PXX_STABLE); make demos/lib-test smoke where wired.

Non-goals

• Not a serious/native-looking IDE — that's the GTK path with its boilerplate; this is the minimalism showcase (Tk, ttk for a modern-enough look).
• Not a compiler/frontend change — a gap the app hits (NilPy feature, tk surface) is filed to the owning lane (N / B), not fixed under E.