Map ViewBorder in the Python host model; record DXF kind blocker

Bounds, scale and rotation are writable with viewport and scale reference
rules. staged_python_view_border_lifecycle_over_real_ipc passes every gate
in DWG; a DXF DRAWINGVIEW reopens as an opaque entity, pinned by a canary.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

docs/plugin-host-model-completion-plan.md

@@ -7,13 +7,13 @@ Build a general Python document model over the OCS host API for all **43 canvas
 As of 20 September 2026, the working branch is `plugin/host-model-api` at
 `a8dd3640` plus the Leader increment, published as draft PR
 [#1391](https://github.com/HakanSeven12/OpenCADStudio/pull/1391). Host API is
-v7. The Python feature has explicit writes for **35 of 43** canvas kinds: 34
-are creatable and `Insert` remains update-only. This is **not** 35 completed
+v7. The Python feature has explicit writes for **36 of 43** canvas kinds: 35
+are creatable and `Insert` remains update-only. This is **not** 36 completed
 kinds: Tolerance, Shape, AttributeEntity, Hatch, MLine, Dimension, MultiLeader, Table, PolygonMesh, PolyfaceMesh, Mesh and Wipeout pass every completion gate.
 AttributeDefinition passes its host and real IPC lifecycle but remains short of
 `Complete` because the previously pinned CAD codec dropped optional ATTDEF
 fields during DXF reads; revalidate that blocker against the current
-`acadrust` revision `7ea4247`. Leader is mapped and integration-tested but blocked at W by three acadrust persistence gaps (see the ledger). Leader, Helix and Underlay are mapped and integration-tested but blocked at W by acadrust persistence gaps, and RasterImage and Viewport are held short of `Complete` by unverifiable or missing oracles (see the ledger). RasterImage is mapped and integration-tested, held short of `Complete` by unverifiable image-dictionary linkage. The other 8 canvas kinds have only `layer`
+`acadrust` revision `7ea4247`. Leader is mapped and integration-tested but blocked at W by three acadrust persistence gaps (see the ledger). Leader, Helix, Underlay and ViewBorder are mapped and integration-tested but blocked at W by acadrust persistence gaps, and RasterImage and Viewport are held short of `Complete` by unverifiable or missing oracles (see the ledger). RasterImage is mapped and integration-tested, held short of `Complete` by unverifiable image-dictionary linkage. The other 7 canvas kinds have only `layer`
 writes through the document model. All 43 have raw typed snapshots. There are
 three internal records and two opaque fallbacks outside the 43 canvas kinds.
 
@@ -123,7 +123,7 @@ The last five may require new engine capabilities rather than only Python conver
 
 ## Handoff start point
 
-Continue with **ViewBorder** (queue item 14). Leader is done except for its W
+Continue with **SectionSymbol** (queue item 15). Leader is done except for its W
 gate; when the engine writes DXF group 340, reads group 213 and the DWG
 R2010+ text-size question is decided, flip the canary assertions in
 `staged_python_leader_lifecycle_over_real_ipc` and mark it `Complete`.
@@ -168,3 +168,4 @@ exact queue above and update statuses with evidence after each increment.
 - Completed `Wipeout` (queue item 11) with rectangular and polygonal clip masks through the shared lifecycle driver; scripted creation matches OCS's native command. The queue now continues with `Underlay`.
 - Mapped `Underlay` against a fixture PDF `UnderlayDefinition`. All gates pass except DXF W: the reader does not convert the degree-valued rotation back to radians, and repeated DXF round trips compound the error (pinned by a canary). The queue now continues with `Viewport`.
 - Mapped `Viewport` with a paper-space owner rule and frozen-layer reference validation. Every gate except a paper-space canvas oracle passes through the shared driver; the kind stays integration-tested. The queue now continues with `ViewBorder`.
+- Mapped `ViewBorder` with viewport and scale reference rules. All gates pass in DWG; DXF loading does not restore the typed entity (pinned by a canary). The queue now continues with `SectionSymbol`.

docs/plugin-host-model-coverage-ledger.md

@@ -1,6 +1,6 @@
 # OCS canvas kind coverage ledger
 
-Use with [the completion plan](plugin-host-model-completion-plan.md). This ledger is current as of 20 September 2026: **35 of 43 canvas kinds have explicit geometry writes** (34 creatable, plus update-only `Insert`), **12 kinds are complete**, and 8 remain layer-only. `Mapped` means at least one non-layer field is exposed for Python writes; it does **not** mean the kind passes the completion gate. `Update-only` means Python creation is unavailable. `Layer-only` means raw inspection and canvas layer edits exist, but geometry is not mapped. Record actual evidence or a blocking issue before changing any status to `Complete`.
+Use with [the completion plan](plugin-host-model-completion-plan.md). This ledger is current as of 20 September 2026: **36 of 43 canvas kinds have explicit geometry writes** (35 creatable, plus update-only `Insert`), **12 kinds are complete**, and 7 remain layer-only. `Mapped` means at least one non-layer field is exposed for Python writes; it does **not** mean the kind passes the completion gate. `Update-only` means Python creation is unavailable. `Layer-only` means raw inspection and canvas layer edits exist, but geometry is not mapped. Record actual evidence or a blocking issue before changing any status to `Complete`.
 
 Completion gate codes: **C** = create through Python document model; **R** = read; **E** = edit defining geometry and another property; **D** = delete; **U** = undo/redo and atomic failure; **I** = real IPC plus GUI/canvas pick or observable behavior; **W** = DWG and DXF save/reopen; **V** = invalid-input checks and untouched-field/reference preservation; **P** = build and load the in-tree bundled plugin with a manifest matching the host toolchain and acadrust source. A kind is `Complete` only when **C/R/E/D/U/I/W/V/P** all pass and its property catalog matches implementation. `Blocked` requires a specific dependency or failing fixture.
 
@@ -41,7 +41,7 @@ Completion gate codes: **C** = create through Python document model; **R** = rea
 | Wipeout | **Complete** | Writable: `insertion_point`, `u_vector`, `v_vector` (the region's world extent), `size`, `flags`, `clipping_enabled`, `brightness`, `contrast`, `fade`, `clip_mode`, `clip_type` and `clip_boundary_vertices` (normalized image coordinates, -0.5..0.5). Read-only: `class_version`, `definition_handle`, `definition_reactor_handle`. Scripted creation matches OCS's native WIPEOUT command, which also leaves the definition link unset. Host validation requires finite non-parallel `u`/`v` vectors, a positive `size`, brightness/contrast/fade within 0..=100, known flags, finite clip vertices, exactly 2 vertices for a rectangular clip and at least 3 for a polygonal one. `staged_python_wipeout_lifecycle_over_real_ipc` (shared `run_mesh_lifecycle`) passes C/R/E/D/U/I/W/V/P: rectangular creation, a switch to a three-vertex polygonal inside-clip with a move in one transaction, canvas wires, eight rejection cases plus an atomic rollback, DWG and DXF reopen with re-edit, and three-step undo/redo. |
 | Underlay | **Integration-tested / blocked at W by acadrust (DXF rotation units)** | Writable: `underlay_type` and `definition_handle` (both fixed by the definition: creation names an existing `UnderlayDefinition`, and a mismatched type or missing definition is rejected), `insertion_point`, `x_scale`, `y_scale`, `z_scale`, `rotation`, `normal`, `flags`, `contrast`, `fade`, `clip_boundary_vertices`, `clip_inverted`. The file path and page live on the definition object, which scripts cannot create or list yet; they reference one the drawing already owns. Host validation requires finite nonzero scales, a finite rotation, a nonzero normal, contrast/fade within 0..=100, known flags, finite clip vertices (none, or at least 2) and an existing definition of the same type. `staged_python_underlay_lifecycle_over_real_ipc` (shared `run_mesh_lifecycle` with a fixture PDF definition) passes C/R/E/D/U/I/V/P and DWG W: creation, a placement/scale/rotation/contrast/fade/clip transaction, canvas wires, eight rejection cases plus an atomic rollback, DWG reopen and re-edit, and three-step undo/redo. **W blocker (engine, pinned by canary assertions):** DXF stores the rotation in degrees but the reader returns it unconverted, so 0.5 rad reopens as 28.6 and each further DXF save-reopen compounds it (1641.4 after a second), silently corrupting the rotation. Not `Complete` until the reader converts degrees back to radians. Not covered: creating definitions from a file path, DWF/DGN fixtures. |
 | Viewport | **Integration-tested** | Writable: `center`, `width`, `height`, `status`, `view_center`, `view_direction`, `view_target`, `lens_length`, `front_clip_z`, `back_clip_z`, `view_height`, `twist_angle`, `custom_scale`, `frozen_layers` (layer handles), `render_mode`, `circle_sides`, `ucs_icon_visible`. Read-only: `id`, snap/grid settings, UCS fields, `clip_boundary_handle`, `style_sheet`, shade-plot, background, visual-style and sun handles, lighting, `ambient_color`, `elevation`. Reference rules: the owner must be a paper-space layout block (a model-space viewport is rejected) and every frozen-layer handle must be an existing layer. Host validation requires finite centers, positive width, height, view height, lens length and scale, a nonzero view direction, finite clip planes and twist, and at least 3 circle sides. `staged_python_viewport_lifecycle_over_real_ipc` (shared `run_mesh_lifecycle`, paper-space owner supplied by the driver) passes C/R/E/D/U/V/W/P: creation in the paper-space block, a move/resize/view-height/twist/frozen-layer transaction, seven rejection cases plus an atomic rollback, DWG and DXF reopen with re-edit, and three-step undo/redo. **Why not `Complete`:** the I gate lacks a canvas oracle because a paper-space viewport only draws on its layout tab, which the driver does not activate; viewport `id` uniqueness within a layout, clip boundary entities and view-to-scale synchronization are not handled by the host. |
-| ViewBorder | Layer-only | Requires linked view records. |
+| ViewBorder | **Integration-tested / blocked at W by acadrust (DXF kind)** | Writable: `min`, `max`, `center` (2-D pairs), `scale`, `rotation_angle`, `active_viewport` and `scale_handle` (both required at creation). `version` is read-only. Reference rules: `active_viewport` must be an existing Viewport entity and `scale_handle` an existing `Scale` object. Host validation requires finite bounds with `min` below `max` on both axes, a positive scale and a finite rotation. `staged_python_view_border_lifecycle_over_real_ipc` (shared `run_mesh_lifecycle`, driver-made viewport and scale fixtures) passes C/R/E/D/U/I/V/P and DWG W: creation, a resize/recenter/scale/rotation transaction, canvas wires, seven rejection cases plus an atomic rollback, DWG reopen and re-edit, and three-step undo/redo. **W blocker (engine, pinned by a canary):** a DXF `DRAWINGVIEW` reopens as a different, opaque entity kind rather than as a ViewBorder, so only DWG restores the typed record. Not `Complete` until DXF loading restores the typed entity. Not covered: the linked view representation and drawing-view definition records. |
 | SectionSymbol | Layer-only | Requires section-view style and point records. |
 | Light | Layer-only | Requires position/target and photometric-state fixture. |
 | Region | Layer-only | Requires valid ACIS region payload. |

docs/plugin-host-model.md

@@ -35,7 +35,7 @@ attached attribute and sequence records. Those fields report `transaction_geomet
 catalog. All 43 canvas kinds also support nonempty `layer` changes through
 the same undoable transaction; internal and opaque variants remain read-only
 through the document model. The adapter accepts only `layer` patches for
-canvas kinds outside its 35 geometry converters. Other writable properties
+canvas kinds outside its 36 geometry converters. Other writable properties
 still report `type_conversion_only`; broader CAD range and cross-property
 checks remain outstanding.
 The host's `entity_snapshot` helper serializes any typed entity as a detached
@@ -91,7 +91,7 @@ Input tokens are bound to the drawing tab that requested the pick. Polling a
 token from another tab returns no result and does not consume it.
 
 Python `doc.entities[handle]` returns a descriptor for every entity. For kinds
-outside the 35-kind generated schema it contains only handle, kind, and layer;
+outside the 36-kind generated schema it contains only handle, kind, and layer;
 `layer` is editable on canvas kinds. `doc.coverage()` enumerates the
 catalog; `doc.coverage("Line")` and `line.coverage` return one entry. For
 covered kinds, the coverage object lists actual readable and editable