Complete MLine host model coverage

Maps vertices, flags, justification, normal, scale and style with host
validation and MLineStyle binding. The host recomputes vertex direction,
miter and element parameters on scripted create/edit, so scripts only supply
positions. staged_python_mline_lifecycle_over_real_ipc passes the full gate
including DWG and DXF reopen.

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: **23 of 43 canvas kinds have explicit geometry writes** (22 creatable, plus update-only `Insert`), **4 kinds are complete**, and 20 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: **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`.
 
 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.
 
@@ -29,7 +29,7 @@ Completion gate codes: **C** = create through Python document model; **R** = rea
 | AttributeEntity | **Complete** | OCS commit `cf2a9235` and adapter commit `9c6b5c3` make nested ATTRIB records addressable by handle while retaining canonical storage in `Insert.attributes`. Host validation binds tag to a definition in the Insert's block, validates placement/text geometry and style references, keeps owner and definition handles read-only, and preserves embedded MTEXT. `staged_python_attribute_entity_lifecycle_over_real_ipc` passes C/R/E/D/U/I/W/V/P with a real block, ATTDEF and Insert: high-level create/read/transaction edit/delete, parent selection, rendered text, atomic invalid tag/height/owner rejection, edited and deleted DWG/DXF reopen, and three-step undo/redo. `nested_insert_attribute_crud_uses_parent_storage_and_undo` additionally proves the child never becomes an orphan flat entity in the host document. |
 | 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 | Layer-only | Requires valid style and vertex fixture. |
+| 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. |
 | MultiLeader | Layer-only | Requires nested context and style fixture. |
 | Table | Layer-only | Requires table style and cell fixture. |