ocs_doc_api: Phase 4 set_view + viewport-view query

- SetViewportView op + GetViewportView query (append-only).
- backend set_viewport_view (update Viewport.view_target/view_height) + viewport_view.
- facade Entity::set_view/viewport_view (Viewport returns Entity).
- spec Viewport methods; api_reference + binding_schema regenerated; mocks + baseline.
- Test phase4_set_view_and_view_query -> 609 host lib + 3 consistency green.
- Phase 4 complete.

crates/ocs_doc_api/IMPLEMENTATION.md

@@ -91,8 +91,10 @@ Phase 2b (annotations/hatch/dimension typed ops), attributes + nested traversal
 - **Done:** `create_viewport(center, width, height, view_target, view_height)` →
   `Operation::CreateViewport`; `bounds()` = center ± width/2,height/2; `transform`
   moves the paper-space center. Covered by `phase4_*` test.
-- **Remaining:** `set_view` (retarget/re-zoom an existing viewport) and a
-  viewport-view query (view target/center/scale DTOs).
+- **Done (set_view + view query):** `set_view(view_target, view_height)` retargets/
+  re-zooms in place (`SetViewportView` op), `viewport_view()` reads the view back
+  (`GetViewportView` query → target + zoom height). Covered by
+  `phase4_set_view_and_view_query` test.
 
 ### Phase 5 — media & misc (read-mostly)
 - **Done:** media/misc families report a **real `kind`** via `GetEntity`

crates/ocs_doc_api/examples/common/mod.rs

@@ -29,6 +29,8 @@ pub struct MockBackend {
     dimension_measurements: HashMap<ObjectId, f64>,
     /// Stored insert attributes.
     attributes_store: HashMap<ObjectId, Vec<(String, String)>>,
+    /// Stored viewport views (target, height).
+    viewport_views: HashMap<ObjectId, ([f64; 3], f64)>,
 }
 
 impl MockBackend {
@@ -138,8 +140,10 @@ impl DocApiBackend for MockBackend {
         }
         Ok(self.alloc("Insert"))
     }
-    fn add_viewport(&mut self, _spec: &ocs_doc_api::ops::ViewportSpec) -> ApiResult<ObjectId> {
-        Ok(self.alloc("Viewport"))
+    fn add_viewport(&mut self, spec: &ocs_doc_api::ops::ViewportSpec) -> ApiResult<ObjectId> {
+        let id = self.alloc("Viewport");
+        self.viewport_views.insert(id, (spec.view_target, spec.view_height));
+        Ok(id)
     }
     fn add_text(&mut self, spec: &ocs_doc_api::ops::TextSpec) -> ApiResult<ObjectId> {
         let id = self.alloc("Text");
@@ -200,6 +204,16 @@ impl DocApiBackend for MockBackend {
     fn block_entities(&self, _block_name: &str) -> ApiResult<Vec<EntityView>> {
         Ok(Vec::new())
     }
+    fn set_viewport_view(&mut self, id: ObjectId, view_target: [f64; 3], view_height: f64) -> ApiResult<()> {
+        if !self.entity_exists(id) {
+            return Err(ApiError::UnknownId(id));
+        }
+        self.viewport_views.insert(id, (view_target, view_height));
+        Ok(())
+    }
+    fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)> {
+        self.viewport_views.get(&id).copied().ok_or(ApiError::UnknownId(id))
+    }
 }
     fn add_vertex(&mut self, id: ObjectId, _at: usize, _point: [f64; 3]) -> ApiResult<()> {
         if self.entity_exists(id) {

crates/ocs_doc_api/spec/entities.toml

@@ -375,6 +375,19 @@ name = "create_viewport"
 args = [{ name = "center", ty = "[f64; 3]" }, { name = "width", ty = "f64" }, { name = "height", ty = "f64" }, { name = "view_target", ty = "[f64; 3]" }, { name = "view_height", ty = "f64" }]
 op = "CreateViewport"
 
+[[family.method]]
+name = "viewport_view"
+kind = "query"
+query = "GetViewportView"
+returns = "([f64; 3], f64)"
+
+[[family.method]]
+name = "set_view"
+kind = "op"
+op = "SetViewportView"
+args = [{ name = "view_target", ty = "[f64; 3]" }, { name = "view_height", ty = "f64" }]
+returns = "()"
+
 # ============================================================================
 # MEDIA & MISC (phase 5, read-mostly) — read-only EntityView, no typed create.
 # These families report a real `kind` via GetEntity and coarse bounds where

crates/ocs_doc_api/src/backend.rs

@@ -75,6 +75,12 @@ pub trait DocApiBackend {
     /// The entities inside a block definition (read-only traversal), as views.
     fn block_entities(&self, block_name: &str) -> ApiResult<Vec<EntityView>>;
 
+    /// Set a viewport's view target + zoom height in place. Viewport-only.
+    fn set_viewport_view(&mut self, id: ObjectId, view_target: [f64; 3], view_height: f64) -> ApiResult<()>;
+
+    /// A viewport's view (target WCS + zoom height). Viewport-only.
+    fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)>;
+
     /// Can `id` be modified in place right now (exists, is the expected family,
     /// not on a locked layer)? Read-only pre-check used before mutations.
     /// Default: existence + not-locked (backends narrow the family check).

crates/ocs_doc_api/src/executor.rs

@@ -237,6 +237,16 @@ pub fn apply_op<B: DocApiBackend>(b: &mut B, op: Operation) -> ApiResult<Receipt
             b.finalize_op();
             OpOutcome::Updated(*id)
         }
+        Operation::SetViewportView { id, view_target, view_height } => {
+            b.can_modify(*id).map_err(|e| match e {
+                ApiError::UnknownId(_) => ApiError::validation(name, format!("unknown ObjectId {id:?}")),
+                other => other,
+            })?;
+            b.push_undo(name);
+            b.set_viewport_view(*id, *view_target, *view_height)?;
+            b.finalize_op();
+            OpOutcome::Updated(*id)
+        }
     };
     Ok(Receipt {
         outcome: Some(outcome),
@@ -279,6 +289,10 @@ pub fn apply_queries<B: DocApiBackend>(b: &mut B, queries: Vec<Query>) -> ApiRes
             Query::GetDimensionMeasurement { id } => QueryResult::DimensionMeasurement(b.dimension_measurement(*id)?),
             Query::GetAttributes { id } => QueryResult::Attributes(b.attributes(*id)?),
             Query::GetBlockEntities { block_name } => QueryResult::BlockEntities(b.block_entities(block_name)?),
+            Query::GetViewportView { id } => {
+                let (target, height) = b.viewport_view(*id)?;
+                QueryResult::ViewportView { target, height }
+            }
         };
         results.push(r);
     }

crates/ocs_doc_api/src/facade.rs

@@ -309,6 +309,18 @@ impl Entity {
         self.session.apply_op(Operation::SetAttribute { id: self.id, tag: tag.to_string(), value: value.to_string() })?;
         Ok(())
     }
+    /// This viewport's view (target WCS + zoom height). Viewport-only.
+    pub fn viewport_view(&self) -> ApiResult<([f64; 3], f64)> {
+        match self.session.one_query(Query::GetViewportView { id: self.id })? {
+            QueryResult::ViewportView { target, height } => Ok((target, height)),
+            _ => Err(ApiError::Transport("unexpected viewport-view result".into())),
+        }
+    }
+    /// Retarget / re-zoom this viewport (one undo step). Viewport-only.
+    pub fn set_view(&self, view_target: [f64; 3], view_height: f64) -> ApiResult<()> {
+        self.session.apply_op(Operation::SetViewportView { id: self.id, view_target, view_height })?;
+        Ok(())
+    }
     pub fn as_solid(&self) -> Option<Solid> {
         // Typed downcast is validated by the view's kind.
         matches!(self.view().ok()?.kind.as_str(), "Solid3D").then(|| Solid::new(self.session.clone(), self.id))

crates/ocs_doc_api/src/gen/api_reference.md

@@ -158,6 +158,11 @@ Paper-space viewport: a width×height window at center looking at view_target wi
 
 - **create_viewport**(`center: [f64; 3], width: f64, height: f64, view_target: [f64; 3], view_height: f64`) -> `Entity`
 
+### Methods
+
+- **viewport_view**(``) -> `([f64; 3], f64)` — query `GetViewportView`
+- **set_view**(`view_target: [f64; 3], view_height: f64`) -> `()` — op `SetViewportView`
+
 ## `Entity` (acadrust `RasterImage`, collection `entities`)
 
 Raster image (read-mostly): GetEntity kind + coarse bounds (insertion + u*width + v*height); generic delete. No typed create in v1.

crates/ocs_doc_api/src/gen/binding_schema.json

@@ -339,7 +339,39 @@
       "acadrust_variant": "Viewport",
       "collection": "entities",
       "handle": "Entity",
-      "methods": [],
+      "methods": [
+        {
+          "args": [],
+          "bulk": false,
+          "fixed": null,
+          "kind": "query",
+          "name": "viewport_view",
+          "op": null,
+          "query": "GetViewportView",
+          "read_only": true,
+          "returns": "([f64; 3], f64)"
+        },
+        {
+          "args": [
+            {
+              "name": "view_target",
+              "ty": "[f64; 3]"
+            },
+            {
+              "name": "view_height",
+              "ty": "f64"
+            }
+          ],
+          "bulk": false,
+          "fixed": null,
+          "kind": "op",
+          "name": "set_view",
+          "op": "SetViewportView",
+          "query": null,
+          "read_only": false,
+          "returns": "()"
+        }
+      ],
       "name": "Viewport"
     },
     {

crates/ocs_doc_api/src/gen/ops_gen.rs

@@ -42,4 +42,6 @@ pub enum Operation {
     CreateDimensionLinear(DimensionSpec),
     // attributes
     SetAttribute { id: ObjectId, tag: String, value: String },
+    // viewport view
+    SetViewportView { id: ObjectId, view_target: [f64; 3], view_height: f64 },
 }

crates/ocs_doc_api/src/gen/query_gen.rs

@@ -30,4 +30,6 @@ pub enum Query {
     GetAttributes { id: ObjectId },
     /// The entity ids + kinds inside a block definition (read-only traversal).
     GetBlockEntities { block_name: String },
+    /// A viewport's view (target + zoom height).
+    GetViewportView { id: ObjectId },
 }

crates/ocs_doc_api/src/ops.rs

@@ -170,6 +170,7 @@ impl crate::gen::Operation {
             CreateHatch(_) => "CreateHatch",
             CreateDimensionLinear(_) => "CreateDimensionLinear",
             SetAttribute { .. } => "SetAttribute",
+            SetViewportView { .. } => "SetViewportView",
         }
     }
 }

crates/ocs_doc_api/src/query.rs

@@ -53,6 +53,8 @@ pub enum QueryResult {
     Attributes(Vec<(String, String)>),
     /// The entities inside a block definition (read-only traversal).
     BlockEntities(Vec<EntityView>),
+    /// A viewport's view: target point (WCS) + zoom height.
+    ViewportView { target: [f64; 3], height: f64 },
 }
 
 /// Convenience: the query name for diagnostics.
@@ -71,6 +73,7 @@ impl crate::gen::Query {
             GetDimensionMeasurement { .. } => "GetDimensionMeasurement",
             GetAttributes { .. } => "GetAttributes",
             GetBlockEntities { .. } => "GetBlockEntities",
+            GetViewportView { .. } => "GetViewportView",
         }
     }
 }

crates/ocs_doc_api/tests/mock_backend.rs

@@ -29,6 +29,8 @@ struct MockBackend {
     dimension_measurements: HashMap<ObjectId, f64>,
     /// Stored insert attributes.
     attributes_store: HashMap<ObjectId, Vec<(String, String)>>,
+    /// Stored viewport views (target, height).
+    viewport_views: HashMap<ObjectId, ([f64; 3], f64)>,
 }
 
 impl MockBackend {
@@ -78,8 +80,10 @@ impl DocApiBackend for MockBackend {
         }
         Ok(self.alloc("Insert"))
     }
-    fn add_viewport(&mut self, _spec: &ocs_doc_api::ops::ViewportSpec) -> ApiResult<ObjectId> {
-        Ok(self.alloc("Viewport"))
+    fn add_viewport(&mut self, spec: &ocs_doc_api::ops::ViewportSpec) -> ApiResult<ObjectId> {
+        let id = self.alloc("Viewport");
+        self.viewport_views.insert(id, (spec.view_target, spec.view_height));
+        Ok(id)
     }
     fn add_text(&mut self, spec: &ocs_doc_api::ops::TextSpec) -> ApiResult<ObjectId> {
         let id = self.alloc("Text");
@@ -140,6 +144,16 @@ impl DocApiBackend for MockBackend {
     fn block_entities(&self, _block_name: &str) -> ApiResult<Vec<EntityView>> {
         Ok(Vec::new())
     }
+    fn set_viewport_view(&mut self, id: ObjectId, view_target: [f64; 3], view_height: f64) -> ApiResult<()> {
+        if !self.entity_exists(id) {
+            return Err(ApiError::UnknownId(id));
+        }
+        self.viewport_views.insert(id, (view_target, view_height));
+        Ok(())
+    }
+    fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)> {
+        self.viewport_views.get(&id).copied().ok_or(ApiError::UnknownId(id))
+    }
 }
     fn add_vertex(&mut self, id: ObjectId, _at: usize, _point: [f64; 3]) -> ApiResult<()> {
         if self.entity_exists(id) {

crates/ocs_doc_api/tests/spec_wire_consistency.rs

@@ -59,6 +59,7 @@ fn operation_variants() -> Vec<String> {
         Operation::CreateHatch(ocs_doc_api::ops::HatchSpec { boundary: vec![], solid: true }),
         Operation::CreateDimensionLinear(ocs_doc_api::ops::DimensionSpec { first_point: [0.0; 3], second_point: [0.0; 3], definition_point: [0.0; 3] }),
         Operation::SetAttribute { id: ObjectId::from_u64(0), tag: String::new(), value: String::new() },
+        Operation::SetViewportView { id: ObjectId::from_u64(0), view_target: [0.0; 3], view_height: 0.0 },
     ];
     // Derive the variant names by serializing a probe of each and reading the
     // bincode variant index -> name map is not available; instead match by
@@ -88,6 +89,7 @@ fn query_variants() -> Vec<String> {
         Query::GetDimensionMeasurement { id: ObjectId::from_u64(0) },
         Query::GetAttributes { id: ObjectId::from_u64(0) },
         Query::GetBlockEntities { block_name: String::new() },
+        Query::GetViewportView { id: ObjectId::from_u64(0) },
     ];
     marker
         .iter()
@@ -144,6 +146,7 @@ const OPERATION_BASELINE: &[&str] = &[
     "CreateHatch",
     "CreateDimensionLinear",
     "SetAttribute",
+    "SetViewportView",
 ];
 
 /// Recorded baseline of the `Query` variant order.
@@ -159,6 +162,7 @@ const QUERY_BASELINE: &[&str] = &[
     "GetDimensionMeasurement",
     "GetAttributes",
     "GetBlockEntities",
+    "GetViewportView",
 ];
 
 #[test]

src/app/doc_api.rs

@@ -311,6 +311,28 @@ impl DocApiBackend for HostSession<'_> {
         Ok(out)
     }
 
+    fn set_viewport_view(&mut self, id: ObjectId, view_target: [f64; 3], view_height: f64) -> ApiResult<()> {
+        let handle = obj_to_handle(id);
+        let entity = self.document().get_entity(handle).cloned().ok_or(ApiError::UnknownId(id))?;
+        let EntityType::Viewport(mut vp) = entity else {
+            return Err(ApiError::Unsupported("SetViewportView is only for Viewport".into()));
+        };
+        vp.view_target = acadrust::types::Vector3::new(view_target[0], view_target[1], view_target[2]);
+        vp.view_height = view_height;
+        if !self.scene_mut().update_entity(EntityType::Viewport(vp)) {
+            return Err(ApiError::Unsupported(format!("entity {id:?} is on a locked layer")));
+        }
+        Ok(())
+    }
+
+    fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)> {
+        let entity = self.document().get_entity(obj_to_handle(id)).ok_or(ApiError::UnknownId(id))?;
+        let EntityType::Viewport(vp) = entity else {
+            return Err(ApiError::Unsupported("GetViewportView is only for Viewport".into()));
+        };
+        Ok(([vp.view_target.x, vp.view_target.y, vp.view_target.z], vp.view_height))
+    }
+
     fn add_vertex(&mut self, id: ObjectId, at: usize, point: [f64; 3]) -> ApiResult<()> {
         let handle = obj_to_handle(id);
         let Some(entity) = self.document().get_entity(handle).cloned() else {
@@ -978,6 +1000,40 @@ mod tests {
         assert!((t.insertion_point.x - 15.0).abs() < 1e-6);
     }
 
+    // ── Phase 4 remaining: set_view + viewport-view query ────────────────────
+
+    #[test]
+    fn phase4_set_view_and_view_query() {
+        let mut app = OpenCADStudio::new_for_test();
+        let mut host = HostSession::new(&mut app, 0);
+        let vp = new_id(&dispatch(&mut host, DocApiEnvelope::op(Operation::CreateViewport(
+            ocs_doc_api::ops::ViewportSpec {
+                center: [50.0, 50.0, 0.0], width: 40.0, height: 30.0,
+                view_target: [0.0, 0.0, 0.0], view_height: 100.0,
+            }))).unwrap());
+
+        // set_view retargets + re-zooms in place.
+        dispatch(&mut host, DocApiEnvelope::op(Operation::SetViewportView {
+            id: vp, view_target: [20.0, 30.0, 0.0], view_height: 50.0 })).unwrap();
+        let Some(EntityType::Viewport(v)) = host.document().get_entity(obj_to_handle(vp)) else { panic!("viewport not found") };
+        assert!((v.view_target.x - 20.0).abs() < 1e-6 && (v.view_height - 50.0).abs() < 1e-6);
+
+        // viewport_view query reads it back.
+        let receipt = dispatch(&mut host, DocApiEnvelope::queries(vec![Query::GetViewportView { id: vp }])).unwrap();
+        match &receipt.query_results[0] {
+            QueryResult::ViewportView { target, height } => {
+                assert!((target[0] - 20.0).abs() < 1e-6 && (*height - 50.0).abs() < 1e-6);
+            }
+            other => panic!("expected viewport view, got {other:?}"),
+        }
+
+        // set_view on a non-viewport is Unsupported.
+        let line = new_id(&dispatch(&mut host, DocApiEnvelope::op(Operation::CreateCurve(
+            Curve2Spec::Line { start: [0.0; 3], end: [1.0; 3] }))).unwrap());
+        assert!(dispatch(&mut host, DocApiEnvelope::op(Operation::SetViewportView {
+            id: line, view_target: [0.0; 3], view_height: 1.0 })).is_err());
+    }
+
     // ── Phase 3 remaining: attributes + nested block traversal ──────────────
 
     #[test]