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F02 — Resize correctness ​

Interactive resize is where windowing abstractions leak first: the platform either notifies you of a new size (X11, Win32, macOS) or negotiates one with you (Wayland's configure/ack/commit). This demo proves a correct, artifact-free implementation per platform and records the exact event sequences.

Requirements ​

  1. Draw a continuously refreshed gradient whose geometry visibly tracks the window size (e.g. corner-anchored diagonal), so stretching or stale buffers are visible.
  2. Survive an aggressive resize storm with no tearing, no stretching, no protocol errors, and no buffer-size mismatch. For Tier-A runs, drive resizes programmatically where the platform allows (X11 XResizeWindow from a second connection; Wayland: log the configure storm the compositor produces; Win32 SetWindowPos loop; macOS setFrame:display:).
  3. Wayland: prove correct semantics — every xdg_surface.configure is logged with its serial; ack_configure is sent with the right serial before the next commit; the committed buffer matches the configured size. An intentional violation (commit a wrong-sized buffer once, behind a --violate flag) and the resulting compositor reaction is part of the findings.
  4. Log every size-change event (resize size=WxH scale=S) and every buffer (re)allocation — allocation strategy (per-resize realloc vs pooling) is a finding.

Instrumentation ​

Mandatory set, plus configure serial=N size=WxH (Wayland), wm_size/wm_sizing kinds (Win32), live_resize_start/end (macOS), configure_notify (X11).

Findings to record ​

  • The full ordered event sequence for one interactive resize, per platform (this feeds event-sequences.md).
  • Who picks the final size — app, server, or negotiation; where a size request can be denied.
  • Buffer lifetime rules during resize (Wayland: when may a wl_buffer be reused?).
  • What happens on the intentional Wayland violation.

Verification ​

Wayland/X11: Tier A. Win32: A[wine] for the programmatic storm; interactive border-drag is Tier C. macOS: programmatic setFrame: is A[ssh]; real live-resize (mouse) is Tier C.