[masarray]

Field regression addressed

The Browser Files path synchronously awaited a full FaultRecordTransferClient.DiscoverAsync recursive traversal (depth 4 / 128 directories / 20k entries) before requesting or rendering the root MMS FileDirectory. A slow, unsupported or timed-out COMTRADE scan could make an otherwise valid root file listing appear entirely unreadable.

Minimal optimized consumer change

• One ARIEC-backed MMS transfer association remains the only network authority; root FileDirectory is read first and presented to the existing native WPF Browser as soon as returned.
• Reuse Iec61850FaultRecordCatalogBuilder.Build to identify supported root CFG/DAT bundles in-memory without a second root directory scan. If the root has no directory candidates, skip expensive recursive discovery entirely.
• When directory candidates exist or root fails, perform optional recursive fault-record discovery with a 30-second linked budget, retain usable root entries if traversal fails or times out, and surface partial-status diagnostics in a compact tooltip.
• Publication remains device/association/read-operation fenced. Downloads are still gated by the existing verified complete-record catalog; no generic arbitrary-file downloads, no additional client/decoder, no new background polling.
• Deterministic regression covers root-only fast-path, early UI publication order, recursive timeout/failure, root failure fallback, and operator cancellation.

Boundaries and acceptance

BCUGE FileDirectory still requires physical replay. Field-specific nested directories may require a separate tested follow-up; this patch does not promise unlimited traversal or generic file download. Stack on #592, no main, ARIEC engine pin, release or control operation changes. Exact-SHA Windows CI required before approval.

[masarray]

D5 exact-source reconciliation — preserve root-first MMS directory, bounded optional COMTRADE scan

Disposition A: Close historical #593 unmerged; current RC already has the tested root-first behavior and extra physical RIO sidecar safeguards. Old head 9fbb92eb9184944153e687118fd8b41196bae273 is exact ancestor of RC 817c3910e8223fa2ac531a4426ada5d2d4bbbe50, compare +1299/-0, merge-base old HEAD.

Canonical replacement: protected draft RC #727/#729 at 817c3910e8223fa2ac531a4426ada5d2d4bbbe50, not published stable.

Unique delta fully reviewed across all 3 paths:

• Models/IedBrowserFileDiscoveryPlanner.cs old bdf53ac19821dddeedd58634cefd433842438b4b→RC 85e46d4beb1d8a2f796a6e5b2b79e44dc660f000: original root-FIRST, bounded optional subdirectory scanning remains intact and its DiscoverAsync body retains all control branches, deadline default 30 s, root-capture publishRoot before scan, early return on complete no-folder root and timeout/failure returns partial root truth. Added IedBrowserRioSidecarBridge.Attach only around engine-proven records and actual root RIO candidates, no unclassified download authority or new parser.
• MainWindow.IedBrowser.cs old f3c107b8180bcb0dcaf4e35be392edcb7dd5df1f→RC 21a0551413a5437a562c463f011204868aab7b3e: same read-root FIRST transfer.ReadRootFileDirectoryAsync delegate, bounded transfer.DiscoverAsync optional enrichment, WPF dispatcher-published early catalog with current owner, CTS, selected IED and connected checks, and truthful root/records partial status. No stale-IED GUI mutation intentionally accepted.
• tests/ARSAS.Tests/M214RootFirstFileDirectoryTests.cs exact old and RC blob 1a9ea238c9f0e665fd72b8f22cd3276911c8d34b; all ordering, bounded timeout, root-first and negative record proof cases retained.

Safety: This is only historical carrier closure. No root-Read new traffic, no control Write/Operate, no parallel Npcap, no engine pin/stable release changes. Existing current exact-head #753 full Windows CI/portable smoke successful is not physical FAT proof.

Follow-up: Physical IED MMS root FileDirectory and subsequent COMTRADE/RIO checks remain open. Current RC owns implementation; old #593 branch and source remain recoverable.