Complete Dimension host model coverage for all nine subtypes

Adds a hand-written flat Dimension model to the adapter (manifest
manual_kinds hook) and a synthetic-property section to the host coverage
policy. The host derives actual_measurement and the base definition point on
scripted create/edit. staged_python_dimension_lifecycle_over_real_ipc passes
the full gate for every subtype including DWG and DXF reopen. Python ints are
now accepted for coordinates and angles.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

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: **24 of 43 canvas kinds have explicit geometry writes** (23 creatable, plus update-only `Insert`), **5 kinds are complete**, and 19 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: **25 of 43 canvas kinds have explicit geometry writes** (24 creatable, plus update-only `Insert`), **6 kinds are complete**, and 18 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.
 
@@ -30,7 +30,7 @@ Completion gate codes: **C** = create through Python document model; **R** = rea
 | Hatch | **Complete** | OCS commit `98b56ef6` and adapter commit `a9b5de8` expose solid and patterned Hatches with elevation/normal, complete pattern definitions, pattern controls, style, association state, boundary paths and seed points. Nested tagged boundary edges use the reusable `{kind, value}` adapter form. Host validation requires closed finite loops, validates line/arc/ellipse/polyline/spline payloads and stored pattern lines, resolves associative boundary handles, and preserves gradient and MPOLYGON payloads as explicitly unsupported. `staged_python_hatch_lifecycle_over_real_ipc` passes C/R/E/D/U/I/W/V/P: Python solid creation, patterned boundary edit, live render-model pattern/boundary checks, selection, atomic invalid scale/association/open-loop/unmapped-property rejection, edited and deleted DWG/DXF reopen, post-reopen edits, and three-step undo/redo. |
 | Leader | **Integration-tested / blocked at W by acadrust** | Fields mapped writable: `vertices` (≥2 finite points, not all coincident), `annotation_handle`, `creation_type`, `path_type`, `dimension_style`, `arrow_enabled`, `hookline_enabled`, `hookline_direction`, `text_height`, `text_width`, `normal`, `horizontal_direction`, `block_offset`, `annotation_offset`. Read-only: `origin`, `dimension_gap`, `arrowhead_type`, `arrow_size`, `byblock_color`. Unmapped but preserved on edit: `override_color` (multi-payload `Color` enum the generator cannot express) and the `dwg_unknown_*` fields. Host reference binding validates that `annotation_handle` exists, is not the leader itself, matches `creation_type` (Text/MText, Tolerance, Insert; `NoAnnotation` forbids a handle) and that `dimension_style` exists; nothing is silently defaulted. `staged_python_leader_lifecycle_over_real_ipc` passes C/R/E/D/U/I/V/P against acadrust `7ea4247`: linked Text annotation, path/height/arrow/offset transaction edit with untouched-field preservation, GUI pick grouping (scripted selection stays exact), seven single-edit rejections plus a cross-entity atomic rollback, four-step undo/redo, real render linework, DWG and DXF reopen and re-edit. Erasing a leader also erases its annotation (scene leader grouping); undo restores both. **W blockers (engine, recorded as canary assertions in the test):** (1) the DXF writer never emits group 340, so a DXF save unlinks the annotation; (2) DXF reads drop `annotation_offset` (group 213 is written but not reassembled); (3) DWG R2010+ does not store `text_height`, `text_width` or `hookline_enabled` (acadrust writes them only for R13–R2007 / R13–R14). Not `Complete` until the engine round-trips (1) and (2); (3) needs a decision to document or make read-only. |
 | MLine | **Complete** | Writable: `vertices` (raw vertex dicts; a script may pass only `position`), `flags` (integer, unknown bits rejected), `justification`, `normal`, `scale_factor`, `style_name`. Read-only: `start_point`, `style_handle`, `style_element_count`. Host validation requires ≥2 finite non-coincident vertices, ≥3 for a closed multiline, a finite nonzero scale and normal, an existing non-empty `MLineStyle`, and per-vertex segments that are either empty or match the style element count. Vertex `direction`/`miter`, segment layout and per-element miter offsets (justification and scale included) are host-derived by `normalize_scripted_mline` on every scripted create or edit, reusing the drawing command's `rebuild_mline_geometry`/`sync_mline_element_parameters`; dash and fill cuts survive an edit unless a vertex moves. `staged_python_mline_lifecycle_over_real_ipc` passes C/R/E/D/U/I/W/V/P: create against the Standard style, a three-vertex/scale/justification transaction edit with untouched-field preservation, corner miter widening and element offsets checked, real `mline_lines` linework before and after DWG and DXF reopen, nine single-edit rejections plus a cross-entity atomic rollback, re-edit after reopen in both formats, deletion, and three-step undo/redo. Known limit: switching to a style with a different element count is rejected until the script also clears the vertices' `segments`; only the rejection is covered by the integration test. |
-| Dimension | Layer-only | Track individual dimension subtypes. |
+| Dimension | **Complete** (all 9 subtypes) | `EntityType::Dimension` wraps a nine-variant enum, so the adapter uses a hand-written flat model (`dimension_model.rs.inc`, wired in through the manifest's `manual_kinds`) and the coverage catalog lists its properties through the policy's `synthetic` section. Python sees `subtype` (fixed at creation), the shared base fields (`text`, `style_name`, `normal`, `text_middle_point`, `attachment_point`, `text_rotation`, `horizontal_direction`, `flip_arrow1/2`, `text_user_positioned`) and only the fields of that subtype; a field from another subtype is rejected, not ignored. `actual_measurement` and the base definition point are host-derived (`normalize_scripted_dimension`, the same recompute grip edits use). Unmapped but preserved: `user_text`, `insertion_point`, `block_name`, version and DWG flags, style overrides in XDATA. Per-subtype status, all verified by `staged_python_dimension_lifecycle_over_real_ipc` (C/R/E/D/U/I/W/V/P; measurement and canvas wires checked for each, DWG and DXF reopen recorded per subtype): Linear (10), Aligned (5), Radius (5), Diameter (10), Angular3Pt (90°), Angular2Ln (90°), Ordinate (5), Arc (5·π/2), LargeRadial (6) — every one creates, reads, derives the right measurement, renders wires, and keeps its measurement through DWG and DXF. Edits (Linear second point/text/attachment, Radius definition point) update the measurement, nine rejection cases plus a cross-entity atomic rollback and three create-time rejections leave the document untouched, and post-reopen re-edit passes in both formats. Not covered: text formatting overrides, arrowheads and other DIMSTYLE overrides stored in XDATA, the anonymous `*D` block. The subtype-specific field meanings for the angular subtypes follow the DXF group-code layout rather than the acadrust convenience constructors. |
 | MultiLeader | Layer-only | Requires nested context and style fixture. |
 | Table | Layer-only | Requires table style and cell fixture. |
 | PolygonMesh | Layer-only | Requires consistent grid/count fixture. |