Fail closed on deferred OpenDSS geometry

docs/dss-geometry-safety.md

@@ -15,30 +15,35 @@ a geometry-defined line.
 
 Until Carson/geometry impedance calculation is implemented:
 
-1. Detect a `Line` that references `geometry=`, `spacing=`, or `wires=`.
+1. Detect a `Line` that references `geometry=`, `spacing=`, `wires=`,
+   `cncables=`, or `tscables=`.
 2. Do not synthesize a `DistLineCode` from OpenDSS `Line` factory defaults.
 3. Do not infer/fabricate conductor count from the balanced `phases` default.
 4. Emit a **parse-time diagnostic** identifying the deferred geometry source.
 5. Preserve the original source object so same-format DSS echo remains lossless.
 6. Keep explicit `linecode=` behavior unchanged.
 7. A one-conductor SWER geometry must never become a three-conductor normalized line.
 
-The preferred long-term representation is an explicit unresolved/deferred line
-reference in the canonical model. If that representation is not yet available,
-the reader should fail closed rather than manufacture electrical parameters.
+PowerIO represents this state explicitly: the `DistLine` remains in the
+network, with its source-derived terminal maps and `linecode: None`. Parsing
+records an error diagnostic because the typed network is not electrically
+complete. A same-format DSS echo still returns the retained source exactly;
+analysis and semantic format writers refuse the unresolved impedance, and no
+writer supplies a placeholder linecode or electrical default.
 
 ## Regression cases
 
 The regression harness in `powerio-dist/tests/dss_geometry_safety.rs` covers:
 
 - a 3-phase overhead `LineGeometry` backed by `WireData`;
 - a single-conductor SWER `LineGeometry`;
+- a 4-conductor `LineSpacing` plus `wires` definition;
 - parse-time diagnostics for deferred geometry;
 - protection against OpenDSS factory-default `R1` leaking into a geometry line.
 
-The tests are currently `#[ignore]` because they encode the target invariant while
-the canonical model's deferred-line representation is being finalized. They are
-intended to become ordinary tests in the implementation PR.
+These are ordinary regression tests. They also verify that retained DSS echoes
+exactly and that every semantic output path reports unresolved impedance as an
+error instead of inventing data.
 
 ## Upstream context
 

docs/src/distribution.md

@@ -6,7 +6,7 @@ A multiconductor network is the conductor level distribution model. OpenDSS and
 using PowerIO
 feeder = parse_file("IEEE13Nodeckt.dss")   # PioModule{MulticonductorNetwork}
 net = feeder.value
-net.data.lines[1]                   # terminal maps, linecode reference
+net.data.lines[1]                   # terminal maps, optional linecode reference
 net.data.linecodes[1]               # per length impedance matrices, SI units
 diagnostics(feeder)                 # what the reader kept, assumed, or refused
 ```

powerio-dist/src/bmopf/read.rs

@@ -1045,7 +1045,7 @@ impl Reader<'_> {
                 bus_to: string(o.get("bus_to")),
                 terminal_map_from: strings(o.get("terminal_map_from")),
                 terminal_map_to: strings(o.get("terminal_map_to")),
-                linecode,
+                linecode: Some(linecode),
                 length,
                 route: None,
                 i_max: floats(o.get("i_max")),

powerio-dist/src/bmopf/write.rs

@@ -806,9 +806,19 @@ impl Writer {
         if !net.lines().is_empty() {
             let mut lines = Map::new();
             for l in net.lines() {
+                let Some(linecode) = l.linecode.as_deref() else {
+                    self.warn(
+                        &C::EMIT_MULTICONDUCTOR_IMPEDANCE_UNRESOLVED,
+                        format!(
+                            "line {} omitted from BMOPF output: its impedance is unresolved",
+                            l.name
+                        ),
+                    );
+                    continue;
+                };
                 let mut o = Map::new();
                 o.insert("length".into(), self.num(l.length, "line length"));
-                o.insert("linecode".into(), json!(l.linecode));
+                o.insert("linecode".into(), json!(linecode));
                 o.insert("bus_from".into(), json!(l.bus_from));
                 o.insert("bus_to".into(), json!(l.bus_to));
                 o.insert("terminal_map_from".into(), json!(l.terminal_map_from));

powerio-dist/src/diagnostics.rs

@@ -66,6 +66,11 @@ pub mod codes {
             "the reader stopped following includes at the nesting depth limit";
         READ_DSS_LINECODE_UNKNOWN = "READ.DSS.LINECODE_UNKNOWN", Warning,
             "a line names a linecode the case does not declare";
+        /// Geometry-backed impedance remains in retained OpenDSS input but is
+        /// absent from the typed network until line constants are calculated.
+        /// Severity `Error`: electrical analysis of that network is unsafe.
+        READ_DSS_IMPEDANCE_UNRESOLVED = "READ.DSS.IMPEDANCE_UNRESOLVED", Error,
+            "a line's retained conductor geometry has not been lowered to impedance matrices";
 
         // EMIT.DSS: what the canonical dss writer cannot state.
         EMIT_DSS_FIELD_DROPPED = "EMIT.DSS.FIELD_DROPPED", Warning,
@@ -230,6 +235,12 @@ pub mod codes {
             "a line polyline was dropped because the target has no polyline field";
         EMIT_MULTICONDUCTOR_SIDECAR_DROPPED = "EMIT.MULTICONDUCTOR.SIDECAR_DROPPED", Warning,
             "a companion file the case text refers to was not written";
+        EMIT_MULTICONDUCTOR_IMPEDANCE_UNRESOLVED =
+            "EMIT.MULTICONDUCTOR.IMPEDANCE_UNRESOLVED", Error,
+            "a line with unresolved impedance was omitted instead of receiving fabricated electrical values";
+        VALIDATE_MULTICONDUCTOR_IMPEDANCE_UNRESOLVED =
+            "VALIDATE.MULTICONDUCTOR.IMPEDANCE_UNRESOLVED", Error,
+            "a line has no resolved impedance and cannot be used for electrical analysis";
 
         // Failures.
         READ_DIST_IO_FAILED = "READ.DIST.IO_FAILED", Error,