Milestone R0.1 — Compact ARStack Browser workflow and 1024px layout QA #135

Goal

ARStack workflow parity at minimum desktop width, without sacrificing working canonical IEC 61850 model and services. This is a functional UI milestone, not a pixel-for-pixel copy.

Concrete UX acceptance

• Compact two-row model/connection bar at 1024px; Open SCL, Save SCL, endpoint, port, Discover IED, Online/Disconnect and status remain legible and within viewport.
• Rendered Qt QA at 1024px checks actual control geometry, signal-tree visibility, and nonblank Model Values label.
• One Browser tree is authoritative; selecting a signal shows observed value, FC, type, quality/timestamp and engineering evidence.
• Active IED tab and common Global Data remain separate and clearly labeled; switching/closing tabs preserves model and association.
• Open SCL and Discover IED share the same Browser after canonical model is built, with explicit post-discovery dataset signal path tracked in Milestone R1 — Open SCL and Discovery converge into verified static reporting #129.
• All Qt, SCL-assisted, C++ and Release Hardening checks succeed on one exact head and Windows portable artifact is available.
• Real device acceptance screenshot captures the minimum-width and normal-width GUI; fixture-only success is not proof of interoperability.

Boundary

Keep validated R0 (#128) lifecycle recovery. Do not rewrite MMS protocol, RCB, DataSet membership, GI or static report-only runtime to improve appearance. Avoid large cards, large bold type and overflow; preserve compact professional engineering density. PR #127 contains the first toolbar and rendered layout QA.

Verified R0.1 evidence

• Exact head 3a3ceef9149fc0dd31b27f4c9232418a68fae0e6: Qt CI PASS with toolbar_1024=visible, signal tree, rendered nonblank model values, switching and reindex; Release Hardening PASS on Linux and Windows staged/installed package verification.
• Windows RC artifact artifact ID 10931054253, SHA256 61da6553edc18152637d3bfd116fce3d32c9310c9b08b8bb90d3644ce0afc979, expires 2026-10-11.
• Still open: real-device screenshots/observations; full complete engineering workflow, including canonical signal catalog, is tracked separately in Milestone R1 — Open SCL and Discovery converge into verified static reporting #129 / stacked PR R1A: canonical Signal Catalog → Dataset Signals → bound static RCB #136.