CHANGELOG:

1.0.1 — QGIS 4 (Qt 6) compatibility (November 2026) One package now
installs and runs on both QGIS generations: QGIS 3.22-3.4x (Qt 5) and
QGIS 4.x (Qt 6, including the 4.2 LTR).

- New qt_compat module resolves every Qt enumeration in both its
scoped (Qt 6 / PyQt6: Qt.CheckState.Checked) and unscoped (Qt 5 /
PyQt5: Qt.Checked) spelling, at import time.

- Attribute-table field types are now built from QMetaType.Type on Qt
6 and QVariant.Type on Qt 5; PyQt6 removed QVariant.Type, which made
every output layer fail to build under QGIS 4.

- Layer-filter, file-widget, selection-mode, button-role and message.

-level enumerations ported to the same resolver.

- Background execution is now gated: under Qt 6 the run executes on
the main thread with the same live progress bar. Qt 6 enforces thread
affinity strictly enough that handing it layers built on a worker
thread could abort QGIS outright, which was the cause of the hard
crashes reported on QGIS 4. The background task is unchanged on QGIS
3, and can be forced on either generation with the
AR_TARSEEM_BACKGROUND environment variable or the
AR-Tarseem/background_run QSettings key.

- QgsTask flag construction hardened against all three PyQt spellings,
with a description-only fallback.

- metadata.txt now declares qgisMaximumVersion=4.99.

- About tab reports the running QGIS and Qt versions and the run mode
in force.

Highlights of the full feature set:

- Watershed delineation: pit filling, D8 flow direction and
accumulation, stream extraction, one catchment per pour point with
snapping to the main flow path, longest flow paths with segment slopes
and three time-of-concentration estimates (Kirpich holistic, Kirpich
10-85, NRCS lag).

- Sub-catchment subdivision by target area, with reaches, junctions,
and per-sub-basin longest flow paths.

- Special Delineation Points: enforce junctions at dam/structure
locations (snapped within the delineation snap radius); divide at the
points only or combined with the area-based subdivision; junctions
renamed with the point name and carrying the point's attributes.

- Reservoir storage routing: any special point can be defined as a
reservoir (elevation-volume curve with spillway and orifice outflow
structures, or a direct storage-discharge table); the combined inflow
is routed by the modified-Puls method and the attenuated outflow
continues downstream. Outputs include inflow and outflow peaks,
attenuation, peak storage and peak stage, plus full routing tables and
interactive charts.

- Hydrology: SCS-CN losses (Curve Number from a raster or a constant
value; adjustable lambda = Ia/S), SCS Unit Hydrograph with adjustable
peak rate factor, four SCS 24-h storm types or custom hyetographs,
fully editable return periods, Thiessen rainfall stations, and TRRL-UK
/ Riyadh / fixed areal reduction.
- Routing: Lag, Muskingum, variable-parameter Muskingum-Cunge.

- Background execution: the engine runs as a QGIS background task, so
QGIS stays fully responsive during a run, with a live progress bar
reporting every stage and catchment.

- Results: attribute tables with peaks and volumes per return period;
hydrograph CSVs and interactive HTML charts for every catchment,
sub-basin, reach and junction, with an editable output window (tail
length and cap) to guarantee complete hydrographs that recede to zero
flow.

- AR-Awdiya export: a new "AR-Awdiya" tab writes the whole model as
a ready-to-run AR-Awdiya project (.json) - catchments, junctions,
reach routing, reservoirs and design storms included - so the network
opens with "Load project" and can be run and reported (Word / PDF)
immediately.

- Interoperability: HEC-HMS .basin export (versions 4.7-4.13,
including true Reservoir elements), .met files per return period, and
a .pdata file with the reservoir Elevation-Storage tables.

RECOMMENDED: download AR-Awdiya, the companion hydrologic network
modeler, for tighter integration —  open the exported files there to
edit the network interactively and to generate Word and PDF documents
of all outputs for engineering reports.

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