Build the network model result on mikeio1d's topology layer

.github/workflows/docs.yml

@@ -36,7 +36,7 @@ jobs:
         version: "1.8.27"
 
     - name: Install dependencies
-      run: uv sync --group dev --group docs --group networks
+      run: uv sync --group dev --group docs --group network
 
     - name: Build documentation
       run: just docs

.github/workflows/full_test.yml

@@ -35,7 +35,7 @@ jobs:
           enable-cache: true
 
       - name: Install dependencies
-        run: uv sync --group test --group networks --no-dev 
+        run: uv sync --group test --group network --no-dev 
 
       - name: Install pandas 2.x
         if: matrix.pandas-version == 'pandas2'
@@ -54,7 +54,7 @@ jobs:
       - name: Test
         run: just test
 
-  build-no-networks:
+  build-no-network:
     runs-on: ubuntu-latest
 
     steps:
@@ -68,7 +68,7 @@ jobs:
           python-version: "3.12"
           enable-cache: true
 
-      - name: Install dependencies (without networks)
+      - name: Install dependencies (without network)
         run: uv sync --group test --no-dev
 
       - name: Test

.github/workflows/notebooks_test.yml

@@ -21,7 +21,7 @@ jobs:
         python-version: "3.14"
         enable-cache: true
     - name: Install dependencies
-      run: uv sync --group test --group notebooks --group networks --no-dev
+      run: uv sync --group test --group notebooks --group network --no-dev
     - name: Test notebooks
       run: |
         uv run pytest tests/notebooks/

adr/010-optional-domain-dependencies.md

@@ -56,7 +56,10 @@ Installation: `pip install modelskill modelskill-network`
 
 **Open Questions:**
 - Should `modelskill[all]` install all optional model types?
-- How to handle version constraints for optional dependencies?
+- How to handle version constraints for optional dependencies? Answered for network
+  support by [ADR-013](013-network-topology-in-mikeio1d.md): the `network` extra names a
+  minimum mikeio1d, because the topology layer ships there. Network support requires
+  whatever Python that release requires.
 - Should optional dependencies be tested in CI for every commit or separately?
 
 ## Status Notes

adr/012-network-format-constructors.md

@@ -1,9 +1,19 @@
 # ADR-012: One Network Constructor per Modelling Product
 
-**Status**: Draft
+**Status**: Accepted, narrowed by [ADR-013](013-network-topology-in-mikeio1d.md)
 
 **Date**: 2026-08
 
+## Narrowed by ADR-013
+
+The constructors, the companion arguments, the extension tables, the coverage test and the
+`.inp` reader are mikeio1d's. It replaced `from_mike` and `from_epanet` with one
+`Network.open` that reads the extension. Naming a constructor after the product that wrote
+the file is still the rule, and mikeio1d applies it.
+
+`NetworkModelResult` hands a path to mikeio1d. The refusal messages for `.out`, `.resx`
+and the formats without a fixture are written there.
+
 ## Context
 
 `Network` is built from result files read through mikeio1d, whose single `Res1D` class opens nine extensions across five products — MIKE 1D (`.res1d`), MIKE 11 (`.res11`), MOUSE (`.prf`, `.crf`, `.xrf`), EPANET (`.res`), SWMM (`.out`), Water Hammer (`.whr`), and `.resx`, which is shared by the last three. There is no per-format reader and no per-format constructor argument, so from mikeio1d's side all nine look alike. modelskill's constructor was named `from_res1d`, and its extension guard was briefly widened to accept everything mikeio1d could read — making the name promise one format while reading nine.

adr/013-network-topology-in-mikeio1d.md

@@ -0,0 +1,48 @@
+# ADR-013: The Network Topology Layer Belongs to mikeio1d
+
+**Status**: Accepted
+
+**Date**: 2026-08
+
+## Context
+
+`modelskill.network` grew into a topology layer of its own: the abstract node/reach/breakpoint types, a `Res1D` adapter, one constructor per modelling product, the `.resx` and `.inp` companions, a table of which extensions we refuse and why, a networkx graph carrying reach lengths and boundary edges, an alias map, and `find`/`recall`/`to_dataset` on top. Roughly 630 code lines, against 25 for mikeio1d's `experimental.to_networkx`, which converts the same file and ignores gridpoints.
+
+Most of those 630 lines do work the upstream function declines to do. The layer still sits on the wrong side of a line ADR-001 drew for mikeio: we call `mikeio.read()` and stop, without modelling dfsu geometry or policing its format list. Here we do both. `Res1D` reads nine extensions across five products; our tables decide which of the nine we accept, and a test fails our CI when a mikeio1d release adds a tenth. The fixtures those tables are checked against — `network.res1d`, `network_cali.res11`, `epanet.res/.resx/.inp` — are copies of mikeio1d's own. Meanwhile `NetworkModelResult` uses five members of `Network`, two of them private, and never traverses the graph.
+
+## Decision
+
+mikeio1d gains an optional network module that builds and owns `Network`. modelskill requires it and consumes what it produces.
+
+| Owner | Pieces |
+|---|---|
+| mikeio1d | abstract types and `BasicNode`/`BasicReach`, the `Res1D` adapter, `Network.open`, the `.resx` and `.inp` companions, the extension policy tables, graph construction with its length and boundary semantics, the alias map, `find`, `recall`, `to_dataframe`, `to_dataset` |
+| modelskill | `NetworkModelResult`, `NodeModelResult`, `NodeObservation`, `ReachObservation`, matching, the MIKE+ station resolver |
+
+`NetworkModelResult` takes a `Network` the upstream module built, or a path it hands to that module. The module is an extra there, carrying networkx and xarray, so `to_dataset()` ships with the class. modelskill's `network` extra requires a mikeio1d release new enough to contain it.
+
+Original IDs become the only identifier a user handles: `NodeObservation.at` takes a node name or a `(reach, distance)` pair, and no longer an integer. The alias integers stay an internal index. They exist because the ID space mixes names and break points, and a tuple cannot be an xarray coordinate value. A saved comparer records the original ID, with the integer beside it as `node_index`, so reloading does not depend on the numbering the installed mikeio1d handed out.
+
+Before anything moved, the loader's output over six fixture loads was recorded: graph edges with their lengths and boundary flags, the alias map, the dataframe, and every answer `find` and `recall` give. Those snapshots are the upstream module's acceptance test.
+
+Phase 1 landed as mikeio1d [#247](https://github.com/DHI/mikeio1d/pull/247), merged 2026-08-19. The snapshots pass there unchanged, twice: against the code moved verbatim, and again after the two product constructors collapsed into `Network.open`. The second pass covers the redesign.
+
+modelskill 1.4.0 waits for the mikeio1d release carrying the module. That release is not out yet.
+
+## Alternatives Considered
+
+**Keep the layer here.** Defensible while the API is private. It means maintaining a format matrix, an EPANET `.inp` parser and a graph contract for traversals we never perform. It also means a CI failure whenever someone else's release adds a format.
+
+**Move only the constructors and companions**, leaving the graph and the abstract types here. Splits the format knowledge from the topology it produces, and leaves `Res1DReach` here as the single adapter for a plug point with no second implementation.
+
+**A separate `modelskill-network` package.** Rejected in ADR-010 for fragmenting the install. It would still own format knowledge that belongs with mikeio1d.
+
+**Ask mikeio1d to guarantee stable node numbering** instead of dropping integers from our API. Puts a promise on someone else's release process, to protect a number users should not be handling.
+
+## Consequences
+
+- ADR-012 is narrowed: the constructors, the companion arguments, the extension tables and the coverage test become mikeio1d's. Naming a constructor after the product that wrote the file is still the rule, and mikeio1d applies it.
+- ADR-010's open question about version constraints for optional dependencies is answered for this feature: the `network` extra pins a minimum mikeio1d, and network support requires whatever Python that release requires.
+- A hand-built network needs mikeio1d installed, since `BasicNode`/`BasicReach` move too. That costs a .NET dependency for users who touch no MIKE file, which only matters for tests and for a backend nobody has written.
+- Dropping `at=<int>` is a breaking change for a signature that shipped in the 1.4.0a3 alpha only, while the network module is opt-in and absent from the API reference. Removing it after 1.4.0 would cost more.
+- Releases become coupled in one direction: a fix to network file reading ships on mikeio1d's schedule. A format mikeio1d adds no longer breaks our CI.

adr/README.md

@@ -30,7 +30,8 @@ Each ADR follows this structure:
 - [ADR-009](009-factory-pattern.md) - Factory pattern for type detection
 - [ADR-010](010-optional-domain-dependencies.md) - Optional dependencies for domain-specific model types (Draft)
 - [ADR-011](011-vertical-pre-extracted-columns.md) - VerticalModelResult ingests pre-extracted columns
-- [ADR-012](012-network-format-constructors.md) - One Network constructor per modelling product (Draft)
+- [ADR-012](012-network-format-constructors.md) - One Network constructor per modelling product (narrowed by ADR-013)
+- [ADR-013](013-network-topology-in-mikeio1d.md) - The network topology layer belongs to mikeio1d
 
 ## Contributing