fix: harden the issue-fix wave after full adversarial review

Five reviewers (PDF, snap, commands, otrack/help, printing) covered the
eight issue-fix commits; every blocker and major is fixed here.

Printing (#1261 follow-up):
- printto params now quote the printer name and pad the empty driver/
  port slots handlers substitute ("Microsoft Print to PDF" was split
  into three arguments and the job silently lost).
- Level-2 enumeration also merges when the level-4 list omits the
  configured default, not only when it is empty; a level-2 error no
  longer discards the default-printer merge.
- The printer list loads in a background task instead of blocking the
  UI thread (level-2 queries can wait out RPC timeouts).
- CTB registration: collisions keep the existing file but now say so,
  and only container-parsed tables are registered (the permissive
  zlib heuristic stays session-only so junk cannot persist).

Snapping (#1030/#1319 follow-up):
- Edge-wire key_vertices gain NaN separators: junctions between
  unrelated mesh edges no longer fabricate phantom midpoints.
- The wire cap counts segments (not separator points) and decimates
  instead of dropping, so dense meshes keep partial endpoint coverage
  instead of losing snap entirely.
- f64 endpoint recovery is a one-shot per-wire map instead of an
  O(points x geoms) rescan on every mouse move.

Commands (#1082 class): the same typed-value-on-web bug also hit
CYLINDER/BOX/WEDGE/CONE/PYRAMID heights, HELIX final height (wrong
value, not just dropped), and SWEEP reference/new lengths — all now
commit as text at exactly those steps, each pinned by a regression
test that fails without the override (plus the missing native-route
twin for EXTRUDE).

PDF (#702 follow-up): heavy CTB pens bypass the Form XObject (their
half-width exceeds the /BBox SDF margin and was flat-chopped), CTM
scale entries round to 4 significant digits (0.01 quantized small
text by ~1%), degenerate quads skip emission, the atlas snapshot is
taken once per export instead of per text entity, and the rounding
comments no longer conflate page points with glyph-plane units.

OTRACK (#1313 follow-up): the guide's polar quantization diverges
from the snapper's drafting-gated polar during window-corner drags —
documented; an orphaned grid-step doc block is reunited with its
function.

src/app/automation.rs

@@ -1771,4 +1771,476 @@ mod tests {
             "EXTRUDE must finish after the typed height"
         );
     }
+
+    /// (min, max) of `coord` over every wire point of the Solid3D entities in
+    /// tab 0's document. Lets the typed-value regression tests below assert
+    /// the committed geometry (the height / swept size), not just that some
+    /// solid appeared.
+    fn solid_wire_extent(
+        app: &OpenCADStudio,
+        coord: impl Fn(&acadrust::types::Vector3) -> f64,
+    ) -> Option<(f64, f64)> {
+        let mut extent: Option<(f64, f64)> = None;
+        for entity in app.tabs[0].scene.document.entities() {
+            let acadrust::EntityType::Solid3D(solid) = entity else {
+                continue;
+            };
+            for point in solid.wires.iter().flat_map(|wire| wire.points.iter()) {
+                let value = coord(point);
+                extent = Some(match extent {
+                    Some((low, high)) => (low.min(value), high.max(value)),
+                    None => (value, value),
+                });
+            }
+        }
+        extent
+    }
+
+    fn solid_count(app: &OpenCADStudio) -> usize {
+        app.tabs[0]
+            .scene
+            .document
+            .entities()
+            .filter(|e| matches!(e, acadrust::EntityType::Solid3D(_)))
+            .count()
+    }
+
+    /// The native twin of `extrude_typed_height_from_dyn_field`: the same
+    /// EXTRUDE Height step driven through the focused command line
+    /// (`CommandInput` → `CommandSubmit`) — the route a desktop user whose
+    /// command line holds keyboard focus takes. Both routes must extrude by
+    /// the typed height (#1082).
+    #[test]
+    fn extrude_typed_height_from_command_line() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        // A closed rectangle in the XY plane.
+        use acadrust::entities::LwVertex;
+        use acadrust::types::Vector2;
+        let rect = acadrust::LwPolyline {
+            vertices: [
+                (-10.0, -10.0),
+                (10.0, -10.0),
+                (10.0, 10.0),
+                (-10.0, 10.0),
+            ]
+            .iter()
+            .map(|(x, y)| LwVertex::new(Vector2::new(*x, *y)))
+            .collect(),
+            is_closed: true,
+            ..Default::default()
+        };
+        let handle = app.tabs[0]
+            .scene
+            .document
+            .add_entity(acadrust::EntityType::LwPolyline(rect))
+            .unwrap();
+
+        let _ = app.update(Message::CommandInput("EXTRUDE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.feed_command(crate::command::StepInput::EntityPick(
+            handle,
+            glam::DVec3::new(-10.0, -10.0, 0.0),
+        ));
+        // Bare Enter finishes selection → Height step.
+        let _ = app.update(Message::CommandFinalize);
+
+        // Focused command line: the typed height goes through the input
+        // widget, not the dynamic-input field buffer.
+        let _ = app.update(Message::CommandInput("5".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+
+        let (min_z, max_z) =
+            solid_wire_extent(&app, |p| p.z).expect("typed height must extrude");
+        assert!(
+            (max_z - min_z - 5.0).abs() < 1e-6,
+            "extruded extent must be the typed 5, got {min_z}..{max_z}"
+        );
+        assert!(
+            app.tabs[0].active_cmd.is_none(),
+            "EXTRUDE must finish after the typed height"
+        );
+    }
+
+    /// Issue #1082 class regression for CYLINDER: the Height prompt accepts
+    /// keyword letters (2Point/Axis), so on web the typed digits land in the
+    /// dynamic-input Height box and the commit must parse them as the scalar
+    /// height instead of resolving an in-plane point whose height is ~0.
+    #[test]
+    fn cylinder_typed_height_from_dyn_field() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+
+        let _ = app.update(Message::CommandInput("CYLINDER".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // Base center and radius through the command line.
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("3".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // → Height step with a Height dynamic-input box.
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+
+        for ch in ["5"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        assert_eq!(app.command_line.input, "");
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.buffer.as_deref() == Some("5"))
+        );
+
+        let _ = app.update(Message::CommandFinalize);
+
+        let (min_z, max_z) = solid_wire_extent(&app, |p| p.z)
+            .expect("typed height must build the cylinder");
+        assert!(
+            (max_z - 5.0).abs() < 1e-6 && min_z.abs() < 1e-6,
+            "cylinder height must be the typed 5, got {min_z}..{max_z}"
+        );
+        assert!(
+            app.tabs[0].active_cmd.is_none(),
+            "CYLINDER must finish after the typed height"
+        );
+    }
+
+    /// Issue #1082 class regression for BOX (and WEDGE, which shares
+    /// `BoxStep::Height`): the typed height must commit as the scalar height,
+    /// not resolve to an in-plane point whose plane-normal ordinate is ~0.
+    #[test]
+    fn box_and_wedge_typed_height_from_dyn_field() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+
+        // ── BOX: 10×5 footprint, typed height 7 ──────────────────────────
+        let _ = app.update(Message::CommandInput("BOX".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("10,5".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        for ch in ["7"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+
+        assert_eq!(solid_count(&app), 1, "BOX must commit after the typed height");
+        let (min_x, max_x) = solid_wire_extent(&app, |p| p.x).expect("box solid");
+        let (min_y, max_y) = solid_wire_extent(&app, |p| p.y).expect("box solid");
+        let (min_z, max_z) = solid_wire_extent(&app, |p| p.z).expect("box solid");
+        assert!(
+            (min_x - 0.0).abs() < 1e-6
+                && (max_x - 10.0).abs() < 1e-6
+                && (min_y - 0.0).abs() < 1e-6
+                && (max_y - 5.0).abs() < 1e-6,
+            "box footprint must stay 10×5, got x {min_x}..{max_x}, y {min_y}..{max_y}"
+        );
+        assert!(
+            (min_z - 0.0).abs() < 1e-6 && (max_z - 7.0).abs() < 1e-6,
+            "box height must be the typed 7, got {min_z}..{max_z}"
+        );
+        assert!(app.tabs[0].active_cmd.is_none());
+
+        // ── WEDGE: same Height step (BoxStep::Height), typed height 9 ────
+        let _ = app.update(Message::CommandInput("WEDGE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("10,5".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        for ch in ["9"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+
+        assert_eq!(solid_count(&app), 2, "WEDGE must commit after the typed height");
+        let (min_z, max_z) = solid_wire_extent(&app, |p| p.z).expect("wedge solid");
+        assert!(
+            (min_z - 0.0).abs() < 1e-6 && (max_z - 9.0).abs() < 1e-6,
+            "wedge height must be the typed 9 (aggregate over both solids), got {min_z}..{max_z}"
+        );
+        assert!(app.tabs[0].active_cmd.is_none());
+    }
+
+    /// Issue #1082 class regression for CONE and PYRAMID: their Height (and
+    /// HeightAfterTopRadius) prompts accept keyword letters, so the typed
+    /// digits must commit through `on_text_input` as the scalar height. Both
+    /// legs drive the Top-radius sub-prompt first so the committed solid is a
+    /// frustum whose top face lands in the wireframe (an apex cone's wires
+    /// carry only the base ellipse), and so the shared
+    /// `HeightAfterTopRadius` arm is covered too.
+    #[test]
+    fn cone_and_pyramid_typed_height_from_dyn_field() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+
+        // ── CONE: base center 0,0 radius 3, top radius 1, typed height 5 ─
+        let _ = app.update(Message::CommandInput("CONE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("3".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        // Top-radius sub-prompt, then the height (HeightAfterTopRadius).
+        let _ = app.update(Message::CommandInput("T".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("1".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        for ch in ["5"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+
+        assert_eq!(solid_count(&app), 1, "CONE must commit after the typed height");
+        let (min_z, max_z) = solid_wire_extent(&app, |p| p.z).expect("cone solid");
+        let (.., max_r) = solid_wire_extent(&app, |p| p.x.hypot(p.y)).expect("cone solid");
+        assert!(
+            (max_r - 3.0).abs() < 1e-6,
+            "cone base radius must stay 3, got {max_r}"
+        );
+        assert!(
+            min_z.abs() < 1e-6 && (max_z - 5.0).abs() < 1e-6,
+            "cone height must be the typed 5, got {min_z}..{max_z}"
+        );
+        assert!(app.tabs[0].active_cmd.is_none());
+
+        // ── PYRAMID: base center 0,0 radius 3, top radius 2, typed height 8
+        let _ = app.update(Message::CommandInput("PYRAMID".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("3".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        let _ = app.update(Message::CommandInput("T".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("2".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Height)
+        );
+        for ch in ["8"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+
+        assert_eq!(
+            solid_count(&app),
+            2,
+            "PYRAMID must commit after the typed height"
+        );
+        let (min_z, max_z) = solid_wire_extent(&app, |p| p.z).expect("pyramid solid");
+        assert!(
+            min_z.abs() < 1e-6 && (max_z - 8.0).abs() < 1e-6,
+            "pyramid height must be the typed 8 (aggregate over both solids), got {min_z}..{max_z}"
+        );
+        assert!(app.tabs[0].active_cmd.is_none());
+    }
+
+    /// Issue #1082 class regression for HELIX: at the Final (height) prompt
+    /// the unfixed dyn commit resolves the typed span into an in-plane point
+    /// anchored at the last pick and commits that point's distance from the
+    /// center as the height — a wrong value whenever the previous pick wasn't
+    /// the center. Entering the top radius through its dynamic box anchors
+    /// the height prompt at (3,0,0), setting up exactly that case.
+    #[test]
+    fn helix_typed_height_from_dyn_field() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+
+        let _ = app.update(Message::CommandInput("HELIX".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // Center, then a typed base radius.
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("2".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // Pick the top radius through the dynamic-input field (the only web
+        // route): the resolved point (3,0,0) becomes the anchor/last point,
+        // off the center — exactly the case where an unfixed point-resolved
+        // typed height would commit the wrong value.
+        for ch in ["3"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+        // → Final step with a Distance dynamic-input box.
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.role == crate::command::DynRole::Distance)
+        );
+        assert_eq!(app.last_point, Some(glam::DVec3::new(3.0, 0.0, 0.0)));
+
+        for ch in ["5"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        assert_eq!(app.command_line.input, "");
+        assert!(
+            app.tabs[0]
+                .dyn_fields
+                .iter()
+                .any(|f| f.buffer.as_deref() == Some("5"))
+        );
+
+        let _ = app.update(Message::CommandFinalize);
+
+        let helix = app.tabs[0]
+            .scene
+            .document
+            .entities()
+            .find_map(|e| match e {
+                acadrust::EntityType::Helix(helix) => Some(helix.clone()),
+                _ => None,
+            })
+            .expect("typed height must create the helix");
+        let height = helix.turn_height * helix.turns;
+        assert!(
+            (height - 5.0).abs() < 1e-6,
+            "helix height must be the typed 5, got {height}"
+        );
+        assert!(
+            (helix.axis_vector.z - 1.0).abs() < 1e-9,
+            "helix axis must stay the plane normal"
+        );
+        assert!(
+            app.tabs[0].active_cmd.is_none(),
+            "HELIX must finish after the typed height"
+        );
+    }
+
+    /// Issue #1082 class regression for SWEEP's reference-scale prompts: the
+    /// typed reference length must be parsed as a length (advancing to the
+    /// new-length prompt), and the typed new length must set the scale
+    /// (new/reference) — visible in the swept solid's size. Unfixed, the
+    /// typed reference length is dropped as a stray first reference point.
+    #[test]
+    fn sweep_typed_scale_lengths_from_dyn_field() {
+        use crate::app::Message;
+        use acadrust::types::Vector3;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        // A unit circle profile swept along a vertical line path.
+        let mut circle = acadrust::Circle::new();
+        circle.radius = 1.0;
+        let profile = app.tabs[0]
+            .scene
+            .document
+            .add_entity(acadrust::EntityType::Circle(circle))
+            .unwrap();
+        let path = app.tabs[0]
+            .scene
+            .document
+            .add_entity(acadrust::EntityType::Line(acadrust::Line::from_points(
+                Vector3::new(0.0, 0.0, 0.0),
+                Vector3::new(0.0, 0.0, 10.0),
+            )))
+            .unwrap();
+
+        let _ = app.update(Message::CommandInput("SWEEP".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // Select the profile, bare Enter finishes selection → path prompt.
+        let _ = app.feed_command(crate::command::StepInput::SelectionComplete(vec![profile]));
+        let _ = app.update(Message::CommandFinalize);
+        // Enter the reference-scale sub-prompt through the command line.
+        let _ = app.update(Message::CommandInput("SCALE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        let _ = app.update(Message::CommandInput("REFERENCE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        // → ReferenceLength prompt with dynamic-input boxes showing.
+        assert!(!app.tabs[0].dyn_fields.is_empty());
+
+        // Typed reference length 2 commits through the dyn-field buffer.
+        for ch in ["2"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        assert_eq!(app.command_line.input, "");
+        let _ = app.update(Message::CommandFinalize);
+        let prompt = app.tabs[0]
+            .active_cmd
+            .as_ref()
+            .map(|c| c.prompt())
+            .unwrap_or_default();
+        assert!(
+            prompt.to_lowercase().contains("new length"),
+            "typed reference length must advance to the new-length prompt, got: {prompt}"
+        );
+
+        // Typed new length 6 → scale 6/2 = 3 → back to the path prompt.
+        for ch in ["6"] {
+            let _ = app.update(Message::CommandAppendChar(ch.to_string()));
+        }
+        let _ = app.update(Message::CommandFinalize);
+        let prompt = app.tabs[0]
+            .active_cmd
+            .as_ref()
+            .map(|c| c.prompt())
+            .unwrap_or_default();
+        assert!(
+            prompt.to_lowercase().contains("sweep path"),
+            "typed new length must return to the path prompt, got: {prompt}"
+        );
+
+        // Picking the path finishes the sweep: the unit circle must have been
+        // scaled by 3, so the swept solid's wires reach radius 3.
+        let _ = app.feed_command(crate::command::StepInput::EntityPick(
+            path,
+            glam::DVec3::new(0.0, 0.0, 5.0),
+        ));
+
+        let (.., max_r) = solid_wire_extent(&app, |p| p.x.hypot(p.y))
+            .expect("sweep must create a solid");
+        assert!(
+            (max_r - 3.0).abs() < 1e-3,
+            "swept radius must be the profile 1 × scale 3, got {max_r}"
+        );
+        assert!(
+            app.tabs[0].active_cmd.is_none(),
+            "SWEEP must finish after the path pick"
+        );
+    }
 }

src/app/mod.rs

@@ -3260,6 +3260,11 @@ pub enum Message {
     /// Web never constructs it — printing opens the PDF preview instead.
     #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
     PrintResult(Result<String, String>),
+    /// Printers enumerated off the UI thread for the Plot dialog's dropdown;
+    /// the dialog opens immediately and the list lands whenever the spooler
+    /// query finishes. Web never constructs it — it has no system printers.
+    #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
+    PrintersListed(Vec<String>),
     /// Open the full Plot / Print dialog (seeds state from the layout).
     PlotDialogOpen,
     /// An edit inside the Plot / Print dialog.
@@ -3290,8 +3295,12 @@ pub enum Message {
     /// Open file dialog to load a CTB/STB plot style table.
     PlotStyleLoad,
     /// Callback when the user picks (or cancels) a CTB/STB file.
-    /// `Ok(None)` = cancelled; `Err` = the picked file failed to parse.
-    PlotStyleLoaded(Result<Option<crate::io::plot_style::PlotStyleTable>, String>),
+    /// `Ok(None)` = cancelled; `Err` = the picked file failed to parse. The
+    /// table carries an optional non-fatal note for the command line (e.g.
+    /// registration kept an already-registered table of the same name).
+    PlotStyleLoaded(
+        Result<Option<(crate::io::plot_style::PlotStyleTable, Option<String>)>, String>,
+    ),
     /// Clear the active plot style table.
     PlotStyleClear,
     /// Open/close the Plot Style panel.

src/app/update/file.rs

@@ -4041,7 +4041,6 @@ impl OpenCADStudio {
             .collect();
         // Keep session-only choices while loading drawing fields from the layout.
         let d = &mut self.plot_dialog;
-        d.printers = crate::io::print_to_printer::list_printers();
         d.plot_styles = crate::io::plot_style::available_ctb_names();
         d.scales = scales;
         d.plot_views = plot_views;
@@ -4124,6 +4123,21 @@ impl OpenCADStudio {
             }
         }
         self.active_modal = Some(crate::app::ModalKind::Plot);
+        // Enumerating printers can block for seconds on spooler RPC (dead
+        // print servers), so it must not run on the UI thread: open the
+        // dialog immediately and let the printer dropdown populate when the
+        // worker replies with Message::PrintersListed. The list is session
+        // state on the dialog, so the late assignment re-renders the pick
+        // list without touching the user's selection. Native only — the web
+        // build has no system printers and offers PDF output alone.
+        #[cfg(not(target_arch = "wasm32"))]
+        {
+            background_task(
+                crate::io::print_to_printer::list_printers,
+                Message::PrintersListed,
+            )
+        }
+        #[cfg(target_arch = "wasm32")]
         Task::none()
     }
 

src/app/update/mod.rs

@@ -8335,12 +8335,19 @@ impl OpenCADStudio {
                     .push_error(crate::tf!("Print failed: {e}").as_ref());
                 Task::none()
             }
+            // The printer list arrives after the Plot dialog already opened
+            // (enumeration runs off the UI thread); assigning it re-renders
+            // the dropdown while leaving the user's selection untouched.
+            Message::PrintersListed(printers) => {
+                self.plot_dialog.printers = printers;
+                Task::none()
+            }
 
             // ── Plot Style Table ──────────────────────────────────────────────
             Message::PlotStyleLoad => {
                 Task::perform(crate::io::pick_plot_style(), Message::PlotStyleLoaded)
             }
-            Message::PlotStyleLoaded(Ok(Some(table))) => {
+            Message::PlotStyleLoaded(Ok(Some((table, note)))) => {
                 if table.is_stb {
                     self.command_line.push_error(
                         crate::t!(
@@ -8364,6 +8371,11 @@ impl OpenCADStudio {
                     )
                     .as_ref(),
                 );
+                // Non-fatal registration feedback — e.g. the picked file was
+                // already registered and the existing table was kept.
+                if let Some(note) = note {
+                    self.command_line.push_info(&note);
+                }
                 self.active_plot_style = Some(table);
                 self.plot_dialog.plot_styles = crate::io::plot_style::available_ctb_names();
                 Task::none()

src/app/view/mod.rs

@@ -771,6 +771,9 @@ bg={bg_ms:.1}ms n={view_count}"
                             // state machine stay untouched.
                             let (_, (ux, uy, _)) = self.drafting_grid_basis(i);
                             let (ux, uy) = (ux.as_dvec3(), uy.as_dvec3());
+                            // Guides quantize to the polar increment even
+                            // while a window-corner drag suppresses polar in
+                            // the snapper (drafting gate) — cosmetic only.
                             let step = self.polar_mode.then_some(self.polar_increment_deg);
                             let perp_on =
                                 self.snapper.is_on(crate::snap::SnapType::Perpendicular);

src/io/mod.rs

@@ -1526,8 +1526,11 @@ mod save_failure_tests {
 /// `Ok(None)` means the user cancelled the dialog; `Err` carries a parse
 /// failure so it reaches the command line instead of dying silently (the
 /// legacy-CTB complaint in #1261d was partly that a file which failed to
-/// parse produced no feedback at all).
-pub async fn pick_plot_style() -> Result<Option<plot_style::PlotStyleTable>, String> {
+/// parse produced no feedback at all). The table is paired with an optional
+/// non-fatal note for the command line — currently the registration
+/// collision message below.
+pub async fn pick_plot_style()
+-> Result<Option<(plot_style::PlotStyleTable, Option<String>)>, String> {
     let dialog = crate::sys::file_dialog()
         .set_title(crate::t!("Load Plot Style Table").as_ref())
         .add_filter(
@@ -1553,17 +1556,137 @@ pub async fn pick_plot_style() -> Result<Option<plot_style::PlotStyleTable>, Str
     })?;
     // Loading a table registers it, the way AutoCAD does: copy it next to the
     // built-ins so it stays in the Plot dialog's table list after restart.
-    // Failures are non-fatal — the table is already applied to this plot.
+    // Only real AutoCAD containers are registered — the permissive heuristic
+    // also accepts junk (any text file, a stray deflate stream), and writing
+    // those into the folder would pollute it permanently — so heuristic
+    // parses stay loadable for this session only. Failures are non-fatal —
+    // the table is already applied to this plot.
     #[cfg(not(target_arch = "wasm32"))]
-    if !table.is_stb {
-        if let (Ok(dir), Some(file_name)) = (plot_style::plot_styles_dir(), path.file_name()) {
-            let registered = dir.join(file_name);
-            if !registered.exists() {
-                let _ = std::fs::copy(&path, &registered);
-            }
-        }
+    let note = should_register_plot_style(&table)
+        .then(|| register_picked_plot_style(&path))
+        .flatten();
+    #[cfg(target_arch = "wasm32")]
+    let note = None;
+    Ok(Some((table, note)))
+}
+
+/// Whether a loaded table should be registered permanently: only real
+/// AutoCAD CTB containers. Named (STB) tables are not offered in the
+/// color-dependent list, and heuristic parses (plain text, a stray deflate
+/// stream) must not be written into the plot-styles folder.
+#[cfg(not(target_arch = "wasm32"))]
+fn should_register_plot_style(table: &plot_style::PlotStyleTable) -> bool {
+    !table.is_stb && table.structured
+}
+
+/// Copy the picked CTB into the per-user plot-styles folder, reporting a
+/// command-line note when the already-registered table was kept instead.
+#[cfg(not(target_arch = "wasm32"))]
+fn register_picked_plot_style(path: &Path) -> Option<String> {
+    plot_style::plot_styles_dir()
+        .ok()
+        .and_then(|dir| register_plot_style_into(&dir, path))
+}
+
+/// Copy `path` into `dir` unless a table with the same file name is already
+/// registered there. A collision keeps the registered file — overwriting it
+/// from a stray pick would silently destroy edits made through the Plot
+/// Style panel — and returns a note naming the kept table so the user hears
+/// about it. Copy failures stay silent: the table is already applied to the
+/// current plot.
+#[cfg(not(target_arch = "wasm32"))]
+fn register_plot_style_into(dir: &Path, path: &Path) -> Option<String> {
+    let file_name = path.file_name()?;
+    let registered = dir.join(file_name);
+    if registered.exists() {
+        return Some(
+            crate::tf!(
+                "'{}' is already registered; the existing table was kept.",
+                file_name.to_string_lossy()
+            )
+            .into_owned(),
+        );
+    }
+    let _ = std::fs::copy(path, &registered);
+    None
+}
+
+#[cfg(all(test, not(target_arch = "wasm32")))]
+mod plot_style_registration_tests {
+    use super::{register_plot_style_into, should_register_plot_style};
+    use crate::io::plot_style::{self, PlotStyleTable};
+
+    fn scratch_dir(tag: &str) -> std::path::PathBuf {
+        let dir = std::env::temp_dir().join(format!(
+            "ocs_ctb_register_{tag}_{}_{}",
+            std::process::id(),
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap()
+                .as_nanos()
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
+    /// A name collision keeps the registered table and surfaces a note
+    /// naming it instead of silently discarding the pick.
+    #[test]
+    fn a_collision_keeps_the_registered_table_and_notes_it() {
+        let dir = scratch_dir("collide");
+        let picked = dir.join("picked.ctb");
+        std::fs::write(&picked, b"freshly picked").unwrap();
+        std::fs::write(dir.join("picked.ctb"), b"already registered").unwrap();
+        let note = register_plot_style_into(&dir, &picked).expect("collision note");
+        assert!(note.contains("picked.ctb"), "{note}");
+        assert!(note.contains("already registered"), "{note}");
+        assert!(note.contains("kept"), "{note}");
+        assert_eq!(
+            std::fs::read(dir.join("picked.ctb")).unwrap(),
+            b"already registered"
+        );
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// Without a collision the picked table is copied and no note is pushed.
+    #[test]
+    fn a_fresh_table_is_copied_without_a_note() {
+        let dir = scratch_dir("fresh");
+        let picked = dir.join("source").join("new.ctb");
+        std::fs::create_dir_all(picked.parent().unwrap()).unwrap();
+        std::fs::write(&picked, b"fresh bytes").unwrap();
+        assert!(register_plot_style_into(&dir, &picked).is_none());
+        assert_eq!(
+            std::fs::read(dir.join("new.ctb")).unwrap(),
+            b"fresh bytes"
+        );
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// Registration is reserved for real AutoCAD containers: the permissive
+    /// heuristic loads junk files for the session but they must never be
+    /// written into the plot-styles folder.
+    #[test]
+    fn only_structured_containers_are_registrable() {
+        let builtin = PlotStyleTable::builtin(plot_style::DEFAULT_PLOT_STYLE).unwrap();
+        assert!(builtin.structured);
+        assert!(should_register_plot_style(&builtin));
+        let mut stb = builtin.clone();
+        stb.is_stb = true;
+        assert!(!should_register_plot_style(&stb));
+
+        // A loose zlib stream without the container header still parses…
+        use std::io::Write;
+        let mut enc =
+            flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::default());
+        enc.write_all(b"description=\"junk\n").unwrap();
+        let mut loose = b"any first line\n".to_vec();
+        loose.extend_from_slice(&enc.finish().unwrap());
+        let junk = PlotStyleTable::from_bytes("junk.ctb", &loose).unwrap();
+        // …but stays session-only.
+        assert!(!junk.structured);
+        assert!(!should_register_plot_style(&junk));
     }
-    Ok(Some(table))
 }
 
 // ── Image file picker ─────────────────────────────────────────────────────

src/io/pdf_export.rs

@@ -506,6 +506,11 @@ pub fn render_pdf_bytes(
     // Glyph Form XObjects keyed by the atlas tile key — shared across pages so
     // multi-layout exports bake each unique glyph once.
     let mut glyph_forms = std::collections::HashMap::new();
+    // Snapshot the atlas once for the whole export (see `atlas_export_snapshot`):
+    // `emit_text` used to re-snapshot per TEXT entity, re-cloning every baked
+    // glyph's strokes and fill triangulation each call while the forms cache
+    // here makes only the first copy useful.
+    let atlas = atlas_export_snapshot(pages);
     for (index, page) in pages.iter().enumerate() {
         append_pdf_page(
             &mut doc,
@@ -513,6 +518,7 @@ pub fn render_pdf_bytes(
             &mut glyph_forms,
             page,
             plot_style,
+            atlas.as_ref(),
         )
         .map_err(|error| format!("Page {}: {error}", index + 1))?;
     }
@@ -520,12 +526,48 @@ pub fn render_pdf_bytes(
     Ok(doc.save(&PdfSaveOptions::default(), &mut warnings))
 }
 
+/// Per-export atlas snapshot: every baked glyph's vector geometry keyed by its
+/// tile `uv_min`, plus the reserved solid-texel key for decoration bars.
+type AtlasExport = (
+    std::collections::HashMap<u64, crate::scene::text::sdf_atlas::GlyphExport>,
+    u64,
+);
+
+/// Snapshot the atlas' baked-glyph geometry ONCE per export, not per TEXT
+/// entity.
+///
+/// `export_table` re-resolves each baked entry through its `Face` and clones
+/// its strokes and fill triangulation, so calling it from every `emit_text`
+/// re-copied the whole atlas for each of the hundreds of text wires a drawing
+/// carries — while holding the global atlas mutex. Export is single-threaded
+/// here and the glyph forms are cached document-wide, so one snapshot serves
+/// every page and entity. Returns `None` when no page carries text (nothing
+/// to snapshot) or the atlas mutex is poisoned (the old per-entity code
+/// skipped text in that case too).
+fn atlas_export_snapshot(pages: &[PdfPageInput]) -> Option<AtlasExport> {
+    let has_text = pages.iter().any(|page| {
+        page.content
+            .wires
+            .iter()
+            .any(|wire| !wire.wire.text_verts.is_empty())
+    });
+    if !has_text {
+        return None;
+    }
+    let atlas = crate::scene::text::sdf_atlas::text_atlas().lock().ok()?;
+    Some((
+        atlas.export_table(),
+        crate::scene::text::sdf_atlas::uv_key(atlas.solid_uv()),
+    ))
+}
+
 fn append_pdf_page(
     doc: &mut PdfDocument,
     image_resources: &mut std::collections::HashMap<(usize, u32, u32), printpdf::XObjectId>,
     glyph_forms: &mut std::collections::HashMap<u64, printpdf::XObjectId>,
     page: &PdfPageInput,
     fallback_plot_style: Option<&PlotStyleTable>,
+    atlas: Option<&AtlasExport>,
 ) -> Result<(), String> {
     // Paper dimensions are validated like the content coordinates below: a
     // NaN/inf/zero sheet (`width < MIN` compares false for NaN) would be
@@ -758,6 +800,7 @@ fn append_pdf_page(
                     emit_text(
                         doc,
                         glyph_forms,
+                        atlas,
                         &mut ops,
                         std::slice::from_ref(&wire.wire),
                         ox,
@@ -1551,10 +1594,12 @@ fn emit_hatch(
 // ── Text (SDF glyph quads → vector strokes / fills) ────────────────────────
 
 /// Format a coordinate as the shortest PDF real with 0.01 resolution
-/// (`3`, `3.5`, `-0.25`). 0.01 pt ≈ 3.5 µm on paper — visually lossless, but
-/// it keeps path operands half the size of printpdf's default
-/// shortest-round-trip f32 text (`41.5445 28.712158` → `41.54 28.71`), which
-/// dominates text-heavy vector pages (#702).
+/// (`3`, `3.5`, `-0.25`). The resolution is in the units of whichever stream
+/// the operand lands in: 0.01 pt (≈ 3.5 µm on paper) for page-space operands,
+/// 0.01 glyph-plane units (≈ 0.1% of the 9-unit atlas tile) for Form XObject
+/// content. Both are visually lossless, and half the size of printpdf's
+/// default shortest-round-trip f32 text (`41.5445 28.712158` → `41.54 28.71`),
+/// which dominates text-heavy vector pages (#702).
 fn pdf_real(v: f32) -> String {
     let rounded = (v * 100.0).round() / 100.0;
     if rounded == rounded.trunc() && rounded.abs() < 1e15 {
@@ -1570,6 +1615,23 @@ fn pdf_real(v: f32) -> String {
     s
 }
 
+/// Round a `cm` scale operand to 4 significant digits (`0.7874015` → `0.7874`).
+///
+/// The glyph `cm` scale entries are pt per glyph-plane unit — ~0.5–0.9 for
+/// small text — so quantizing them on the absolute 0.01 grid used for
+/// translations fixed the ratio by up to ~1%, accumulating visible
+/// advance-width drift across a text run. Four significant digits keep the
+/// relative error within ~0.05%; translations stay at 0.01 because they are
+/// absolute page positions, not ratios.
+fn round_sig4(v: f64) -> f64 {
+    if !v.is_finite() || v == 0.0 {
+        return v;
+    }
+    let decimals = (3 - v.abs().log10().floor() as i32).clamp(0, 17);
+    let factor = 10f64.powi(decimals);
+    (v * factor).round() / factor
+}
+
 /// Serialize one glyph's vector geometry as a compact PDF content stream in
 /// glyph-plane units (the 9-unit space the atlas tile spans).
 ///
@@ -1698,9 +1760,13 @@ fn adapt_text_color([r, g, b]: [f32; 3]) -> [f32; 3] {
 /// quad's `uv_min` and map it into that quad by affine interpolation of the
 /// plane rect — so a stroke (LFF) font emits polylines and a filled TrueType
 /// glyph emits filled triangles, exactly where the SDF quad sits.
+///
+/// The atlas geometry comes from `atlas`, the export-wide snapshot taken once
+/// in `render_pdf_bytes`.
 fn emit_text(
     doc: &mut PdfDocument,
     glyph_forms: &mut std::collections::HashMap<u64, printpdf::XObjectId>,
+    atlas: Option<&AtlasExport>,
     ops: &mut Vec<Op>,
     wires: &[WireModel],
     ox: f64,
@@ -1714,12 +1780,8 @@ fn emit_text(
     if wires.iter().all(|w| w.text_verts.is_empty()) {
         return;
     }
-    // Snapshot the atlas' baked-glyph geometry once; drop the lock before use.
-    let (table, solid_key) = {
-        let Ok(atlas) = sdf_atlas::text_atlas().lock() else {
-            return;
-        };
-        (atlas.export_table(), sdf_atlas::uv_key(atlas.solid_uv()))
+    let Some((table, solid_key)) = atlas else {
+        return;
     };
 
     // `Op::SetLineDashPattern` is persistent graphics state and the wire pass
@@ -1816,11 +1878,79 @@ fn emit_text(
                 let uy = (br[1] - bl[1]) / sx as f64;
                 let vx = (tl[0] - bl[0]) / sy as f64;
                 let vy = (tl[1] - bl[1]) / sy as f64;
+                // Degenerate quad (collapsed corners → zero-area transform):
+                // skip emission, mirroring the plane guard above, instead of
+                // letting a near-zero scale reach the pen division below and
+                // paint a page-spanning hairline.
+                let det = ux * vy - uy * vx;
+                if det.abs() < 1e-9 {
+                    continue;
+                }
                 let origin_x = bl[0] - ux * pmin[0] as f64 - vx * pmin[1] as f64;
                 let origin_y = bl[1] - uy * pmin[0] as f64 - vy * pmin[1] as f64;
                 let m2pt = MM_TO_PT as f64;
                 let r2 = |v: f64| ((v * 100.0).round() / 100.0) as f32;
 
+                if let Some(ctb_pen) = lw_override.filter(|_| ge.fill_tris.is_empty()) {
+                    // Heavy CTB pen: bypass the glyph Form XObject and stroke the
+                    // centrelines DIRECTLY in page space. The Form /BBox is the
+                    // atlas tile rect, whose 1.5-unit SDF spread margin bounds
+                    // the nominal pen — an absolute CTB lineweight is arbitrary
+                    // pt and can exceed it (2.5 mm text + 1.0 mm pen → 1.79-unit
+                    // half-width > 1.5), squaring round caps off at the tile
+                    // edge. The override is per text entity, so every stroked
+                    // glyph of the entity takes this one path — no per-glyph
+                    // mixing of Form and direct pens (a filled TrueType
+                    // fallback glyph keeps its Form; it has no pen to clip).
+                    // The Form-dedupe win is irrelevant for the rare heavy-pen
+                    // case. The pen is already divided by the page CTM scale
+                    // above, so it stays absolute on paper.
+                    if last_outline.map(|c| color_differs(c, [r, g, b])).unwrap_or(true) {
+                        ops.push(Op::SetOutlineColor {
+                            col: Color::Rgb(Rgb {
+                                r,
+                                g,
+                                b,
+                                icc_profile: None,
+                            }),
+                        });
+                        last_outline = Some([r, g, b]);
+                    }
+                    ops.push(Op::SetOutlineThickness {
+                        pt: Pt(if ge.bold {
+                            ctb_pen * 1.7
+                        } else {
+                            ctb_pen
+                        }),
+                    });
+                    let map = |p: [f32; 2]| -> Point {
+                        let u = ((p[0] - pmin[0]) / sx) as f64;
+                        let v = ((p[1] - pmin[1]) / sy) as f64;
+                        point(
+                            bl[0] + u * (br[0] - bl[0]) + v * (tl[0] - bl[0]),
+                            bl[1] + u * (br[1] - bl[1]) + v * (tl[1] - bl[1]),
+                        )
+                    };
+                    for stroke in &ge.strokes {
+                        if stroke.len() < 2 {
+                            continue;
+                        }
+                        ops.push(Op::DrawLine {
+                            line: Line {
+                                points: stroke
+                                    .iter()
+                                    .map(|&p| LinePoint {
+                                        p: map(p),
+                                        bezier: false,
+                                    })
+                                    .collect(),
+                                is_closed: false,
+                            },
+                        });
+                    }
+                    continue;
+                }
+
                 // Colour ops go OUTSIDE the per-glyph q/Q: the CTM must be
                 // scoped, but fill colour has to persist past the Q or the
                 // next glyph would fill with the page-default black despite
@@ -1840,12 +1970,13 @@ fn emit_text(
                         last_fill = Some([r, g, b]);
                     }
                 } else {
-                    // Stroke (LFF/SHX pen) font or hollow glyph.
-                    // Match the SDF atlas' nominal glyph-space pen instead of
-                    // borrowing the entity lineweight: Roman Duplex and similar
+                    // Stroke (LFF/SHX pen) font or hollow glyph, nominal pen:
+                    // match the SDF atlas' glyph-space pen instead of borrowing
+                    // the entity lineweight — Roman Duplex and similar
                     // multi-stroke faces rely on that band to close the narrow
-                    // gaps between parallel centrelines. An explicit CTB
-                    // lineweight still wins and stays absolute under the plot CTM.
+                    // gaps between parallel centrelines. (An explicit CTB
+                    // lineweight never reaches this Form path; it takes the
+                    // direct heavy-pen path above.)
                     if last_outline.map(|c| color_differs(c, [r, g, b])).unwrap_or(true) {
                         ops.push(Op::SetOutlineColor {
                             col: Color::Rgb(Rgb {
@@ -1857,28 +1988,27 @@ fn emit_text(
                         });
                         last_outline = Some([r, g, b]);
                     }
-                    let pen = if let Some(ctb_pen) = lw_override {
-                        if ge.bold {
-                            ctb_pen * 1.7
-                        } else {
-                            ctb_pen
-                        }
-                    } else {
-                        let glyph_unit_mm = (((tl[0] - bl[0]).powi(2) + (tl[1] - bl[1]).powi(2))
-                            .sqrt()
-                            / sy.abs() as f64) as f32;
+                    let glyph_unit_mm = (((tl[0] - bl[0]).powi(2) + (tl[1] - bl[1]).powi(2))
+                        .sqrt()
+                        / sy.abs() as f64) as f32;
+                    let pen =
                         (2.0 * sdf_atlas::stroke_pen_half_units(ge.bold) * glyph_unit_mm * MM_TO_PT)
-                            .max(0.1)
-                    };
+                            .max(0.1);
                     stroke_pen = Some(((pen * 100.0).round() / 100.0).max(0.1));
                 }
                 ops.push(Op::SaveGraphicsState);
                 ops.push(Op::SetTransformationMatrix {
                     matrix: printpdf::CurTransMat::Raw([
-                        r2(ux * m2pt),
-                        r2(uy * m2pt),
-                        r2(vx * m2pt),
-                        r2(vy * m2pt),
+                        // Scale entries carry the pt-per-glyph-unit ratio
+                        // (~0.5–0.9 for small text) and are rounded to 4
+                        // significant digits — the 0.01 absolute grid would
+                        // quantize them by ~1% and visibly drift the advance
+                        // width across a text run.
+                        round_sig4(ux * m2pt) as f32,
+                        round_sig4(uy * m2pt) as f32,
+                        round_sig4(vx * m2pt) as f32,
+                        round_sig4(vy * m2pt) as f32,
+                        // Translations are absolute page positions: 0.01 pt.
                         r2((origin_x + ox) * m2pt),
                         r2((origin_y + oy) * m2pt),
                     ]),
@@ -1886,10 +2016,12 @@ fn emit_text(
                 if let Some(pen) = stroke_pen {
                     // Line width is GEOMETRIC state: the CTM above scales a `w`
                     // set before it, so the pen is re-set per glyph, under its
-                    // own CTM, pre-divided by the quad's area scale to keep the
-                    // on-paper width identical to stroking in page units.
-                    let det = (ux * vy - uy * vx).abs() * m2pt * m2pt;
-                    let unit_scale = det.sqrt().max(1e-6) as f32;
+                    // own CTM, pre-divided by the quad's transform.
+                    // sqrt(|det|) is the geometric-mean width — it matches the
+                    // on-screen SDF band, and is exact only for uniform scales
+                    // (an anisotropic quad strokes marginally off in its thin
+                    // axis, the same compromise the SDF render makes).
+                    let unit_scale = (det.abs() * m2pt * m2pt).sqrt() as f32;
                     ops.push(Op::SetOutlineThickness {
                         pt: Pt((pen / unit_scale * 100.0).round() / 100.0),
                     });
@@ -1912,7 +2044,7 @@ fn emit_text(
                     transform: Default::default(),
                 });
                 ops.push(Op::RestoreGraphicsState);
-            } else if key == solid_key {
+            } else if key == *solid_key {
                 // Decoration bar (underline / overline / strike): the quad is a
                 // solid-texel rectangle — fill it directly from its corners.
                 if last_fill.map(|c| color_differs(c, [r, g, b])).unwrap_or(true) {
@@ -2030,6 +2162,19 @@ mod tests {
         assert_eq!(downsample_target(2, 2, 1500.0, 150), (1, 1));
     }
 
+    #[test]
+    fn round_sig4_keeps_four_significant_digits() {
+        // Small-text pt-per-unit ratios keep 4 decimals…
+        assert!((round_sig4(0.78740156) - 0.7874).abs() < 1e-12);
+        assert!((round_sig4(-0.512399) - (-0.5124)).abs() < 1e-12);
+        // …larger magnitudes shift the kept digits, not the precision…
+        assert!((round_sig4(7.8740156) - 7.874).abs() < 1e-12);
+        assert!((round_sig4(28.346456) - 28.35).abs() < 1e-12);
+        // …and tiny ratios gain decimals instead of collapsing onto 0.01/0.1.
+        assert!((round_sig4(0.078740156) - 0.07874).abs() < 1e-12);
+        assert_eq!(round_sig4(0.0), 0.0);
+    }
+
     #[test]
     fn plot_quality_dpi_caps_match_the_dialog_presets() {
         assert_eq!(PlotQuality::High.target_dpi(), None);

src/io/plot_style.rs

@@ -166,6 +166,12 @@ pub struct PlotStyleTable {
     pub name: String,
     /// Whether this is a named-style (STB) table rather than color-based (CTB).
     pub is_stb: bool,
+    /// Whether the bytes parsed through the real AutoCAD container
+    /// (`PIAFILEVERSION_2.0,CTBVER1/STBVER1,compress`) rather than the
+    /// permissive heuristic fallback that also accepts loose text or deflate
+    /// streams. Only container tables are registered permanently; heuristic
+    /// parses stay loadable for the session only.
+    pub structured: bool,
     pub description: String,
     pub scale_factor: f32,
     pub apply_factor: bool,
@@ -183,6 +189,7 @@ impl PlotStyleTable {
         PlotStyleTable {
             name: name.into(),
             is_stb: false,
+            structured: false,
             description: String::new(),
             scale_factor: 1.0,
             apply_factor: false,
@@ -207,8 +214,12 @@ impl PlotStyleTable {
     pub fn from_bytes(name: impl Into<String>, raw: &[u8]) -> Result<Self, String> {
         let name = name.into();
         let is_stb = name.to_ascii_lowercase().ends_with(".stb");
-        let text = decompress_ctb(raw)?;
-        parse_plot_style_text(&text, name, is_stb)
+        let (text, structured) = decompress_ctb(raw)?;
+        let mut table = parse_plot_style_text(&text, name, is_stb)?;
+        // Record the parse route so callers can refuse to permanently
+        // register tables that only the heuristic accepted.
+        table.structured = structured;
+        Ok(table)
     }
 
     pub fn builtin(name: &str) -> Result<Self, String> {
@@ -434,17 +445,19 @@ impl PlotStyleTable {
 
 // ── Deflate helpers ───────────────────────────────────────────────────────────
 
-/// Decompress a CTB/STB file's raw bytes into the text content.
-///
-fn decompress_ctb(data: &[u8]) -> Result<String, String> {
+/// Decompress a CTB/STB file's raw bytes into the text content, reporting
+/// whether the real AutoCAD container was used. `false` means the permissive
+/// heuristic fallback (skip the first line, try zlib/deflate) accepted it.
+fn decompress_ctb(data: &[u8]) -> Result<(String, bool), String> {
     // CTB and STB files share this container; only the embedded version tag
     // differs ("CTBVER1" vs "STBVER1"). Accept both so real AutoCAD STB files
     // take the structured path instead of falling through to the raw
     // deflate heuristic below (where they fail with a confusing zlib error).
     const CTB_PREFIX: &[u8] = b"PIAFILEVERSION_2.0,CTBVER1,compress\r\npmzlibcodec";
     const STB_PREFIX: &[u8] = b"PIAFILEVERSION_2.0,STBVER1,compress\r\npmzlibcodec";
+    let structured = data.starts_with(CTB_PREFIX) || data.starts_with(STB_PREFIX);
     let mut decoded = Vec::new();
-    if data.starts_with(CTB_PREFIX) || data.starts_with(STB_PREFIX) {
+    if structured {
         if data.len() < 60 {
             return Err("CTB header is truncated".into());
         }
@@ -490,7 +503,8 @@ fn decompress_ctb(data: &[u8]) -> Result<String, String> {
     if decoded.last() == Some(&0) {
         decoded.pop();
     }
-    String::from_utf8(decoded).map_err(|e| format!("CTB text is not UTF-8: {e}"))
+    let text = String::from_utf8(decoded).map_err(|e| format!("CTB text is not UTF-8: {e}"))?;
+    Ok((text, structured))
 }
 
 /// Compress plot-style text content as a CTB/STB file.
@@ -694,6 +708,7 @@ fn parse_plot_style_text(text: &str, name: String, is_stb: bool) -> Result<PlotS
     Ok(PlotStyleTable {
         name,
         is_stb,
+        structured: false,
         description,
         scale_factor,
         apply_factor,
@@ -785,12 +800,36 @@ mod round_trip_tests {
     fn stb_container_headers_parse() {
         let mut bytes =
             compress_ctb(PlotStyleTable::identity("x").to_text().as_bytes()).expect("compress");
-        // "PIAFILEVERSION_2.0," is 18 bytes, so 19..22 holds the "CTB" tag.
+        // "PIAFILEVERSION_2.0," is 19 bytes, so 19..22 holds the "CTB" tag.
         bytes[19..22].copy_from_slice(b"STB");
         let table = PlotStyleTable::from_bytes("mystyles.stb", &bytes).expect("stb parses");
         assert!(table.is_stb);
     }
 
+    /// The parse route must be visible to callers: only real AutoCAD
+    /// containers may be registered permanently, while heuristic parses stay
+    /// loadable for the session only.
+    #[test]
+    fn only_container_parses_are_flagged_structured() {
+        let container =
+            compress_ctb(PlotStyleTable::identity("x").to_text().as_bytes()).expect("compress");
+        assert!(PlotStyleTable::from_bytes("a.ctb", &container)
+            .unwrap()
+            .structured);
+
+        // The same payload without the container header still loads through
+        // the permissive heuristic, but must not claim the structured route.
+        use std::io::Write;
+        let mut enc =
+            flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::default());
+        enc.write_all(b"description=\"loose\n").unwrap();
+        let zlib = enc.finish().unwrap();
+        let mut loose = b"any first line\n".to_vec();
+        loose.extend_from_slice(&zlib);
+        let table = PlotStyleTable::from_bytes("b.ctb", &loose).unwrap();
+        assert!(!table.structured);
+    }
+
     /// Named tables are refused with the actual limitation, not a generic
     /// invalid-name error (and without touching the file system).
     #[test]

src/io/print_to_printer.rs

@@ -117,11 +117,16 @@ fn windows_printers() -> std::io::Result<Vec<String>> {
     // but on Windows 11 it can miss per-user network printers that only the
     // spooler RPC (level 2) reports (#1261a). The level-2 query is expensive —
     // it opens every remote connection and can wait out RPC timeouts on dead
-    // print servers — so it only runs when the cached query came back empty;
-    // machines whose level-4 list works never pay for it. (The flags stay
-    // LOCAL|CONNECTIONS on purpose: the EnumPrintersW documentation restricts
-    // level 4 to exactly those flags, and PRINTER_ENUM_NETWORK is only valid
-    // with level 1, so completeness comes from the level-2 retry, not flags.)
+    // print servers — so it only runs when the cached list looks incomplete:
+    // either it came back empty, or it does not contain the configured
+    // default printer, which is exactly the case where the default is one of
+    // the hidden per-user connections. Machines whose level-4 list already
+    // covers the default never pay for it. A level-2 failure is not fatal:
+    // the level-4 names stand and the default merge below still guarantees
+    // the default is offered. (The flags stay LOCAL|CONNECTIONS on purpose:
+    // the EnumPrintersW documentation restricts level 4 to exactly those
+    // flags, and PRINTER_ENUM_NETWORK is only valid with level 1, so
+    // completeness comes from the level-2 retry, not flags.)
     let mut names = enum_printer_names(
         4,
         PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS,
@@ -129,18 +134,26 @@ fn windows_printers() -> std::io::Result<Vec<String>> {
         // pPrinterName is the first field of PRINTER_INFO_4W.
         0,
     )?;
-    if names.is_empty() {
-        names = enum_printer_names(
+    let default = windows_default_printer();
+    let hides_default = default
+        .as_ref()
+        .is_some_and(|name| !names.iter().any(|n| n.eq_ignore_ascii_case(name)));
+    if names.is_empty() || hides_default {
+        // Errors here are deliberately swallowed: falling through with the
+        // level-4 names still lets the default merge below run.
+        if let Ok(extra) = enum_printer_names(
             2,
             PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS,
             std::mem::size_of::<PRINTER_INFO_2W>(),
             // pPrinterName is the second pointer field of PRINTER_INFO_2W.
             std::mem::size_of::<usize>(),
-        )?;
+        ) {
+            names.extend(extra);
+        }
     }
     // The spooler's own default is authoritative even when enumeration missed
     // it; always offer it explicitly so the list can never hide it (#1261b).
-    if let Some(default) = windows_default_printer() {
+    if let Some(default) = default {
         if !names.iter().any(|name| name.eq_ignore_ascii_case(&default)) {
             names.push(default);
         }
@@ -301,6 +314,18 @@ fn windows_default_printer() -> Option<String> {
     (!trimmed.is_empty()).then(|| trimmed.to_string())
 }
 
+/// Build the `lpParameters` string for the shell `printto` verb. The verb
+/// passes four arguments — file, printer, driver, port — and registered PDF
+/// handlers quote each slot (Acrobat: `/t "%1" "%2" "%3" "%4"`), i.e. they
+/// whitespace-tokenise the parameter string. A bare printer name therefore
+/// shatters on spaces ("Microsoft Print to PDF" becomes printer=Microsoft,
+/// driver=Print, port=to PDF) and the job is lost with all UI suppressed.
+/// Quote the name and pass the empty driver/port slots handlers expect.
+#[cfg(target_os = "windows")]
+fn printto_params(printer: &str) -> String {
+    format!("\"{printer}\" \"\" \"\"")
+}
+
 /// Probe the spooler for `name` before dispatching a job (#1261c).
 /// `OpenPrinterW` with no `PRINTER_DEFAULTSW` is a pure
 /// existence/permission check: it spools nothing and shows no UI, and gives a
@@ -368,11 +393,24 @@ fn describe_shell_execute_failure(code: u32) -> &'static str {
 #[cfg(all(test, target_os = "windows"))]
 mod printer_buffer_tests {
     use super::{
-        describe_shell_execute_failure, ensure_printer_exists, windows_default_printer,
-        windows_printer_names,
+        describe_shell_execute_failure, ensure_printer_exists, printto_params,
+        windows_default_printer, windows_printer_names,
     };
     use windows_sys::Win32::Graphics::Printing::{PRINTER_INFO_2W, PRINTER_INFO_4W};
 
+    /// The `printto` parameters are whitespace-tokenised by registered PDF
+    /// handlers (Acrobat: `/t "%1" "%2" "%3" "%4"`), so the printer name must
+    /// arrive quoted with the empty driver/port slots padded — a bare
+    /// multi-word name used to split into printer/driver/port garbage.
+    #[test]
+    fn printto_params_quote_the_printer_and_pad_empty_slots() {
+        assert_eq!(
+            printto_params("Microsoft Print to PDF"),
+            "\"Microsoft Print to PDF\" \"\" \"\""
+        );
+        assert_eq!(printto_params("LaserJet"), "\"LaserJet\" \"\" \"\"");
+    }
+
     #[test]
     fn printer_names_stay_within_the_returned_buffer() {
         assert!(
@@ -682,8 +720,15 @@ fn dispatch_to_printer_opts(path: &std::path::Path, opts: &PrintOptions) -> Resu
         if let Some(name) = &target {
             ensure_printer_exists(name)?;
         }
+        // One construction point serves both the resolved default and a
+        // named selection (`target` covers the two); the name is quoted via
+        // `printto_params` so handlers cannot tokenize it on spaces.
         let (verb, params, label) = match &target {
-            Some(name) => (wide("printto"), Some(wide(name)), name.clone()),
+            Some(name) => (
+                wide("printto"),
+                Some(wide(&printto_params(name))),
+                name.clone(),
+            ),
             None => (wide("print"), None, "default printer".to_string()),
         };
         let params_ptr = params

src/modules/draw/draw/helix.rs

@@ -353,6 +353,21 @@ impl CadCommand for HelixCommand {
         }
     }
 
+    // The Final step's dynamic box is the helix height — a span along the
+    // plane normal — but its typed value would otherwise resolve into an
+    // in-plane point anchored at the last pick, and `on_point` commits that
+    // point's distance from the center as the height: a wrong value whenever
+    // the previous pick (e.g. the top radius) wasn't the center. This is the
+    // only entry route on web, where the canvas — not the command line —
+    // holds keyboard focus. `on_text_input` parses the same string the
+    // command-line path would (keywords and `parse_typed_length`), so both
+    // entry routes behave identically (#1082). The Base/TopRadius steps keep
+    // committing typed digits as points: their distance from the center IS
+    // the radius.
+    fn dyn_commit_as_text(&self) -> bool {
+        self.step == Step::Final
+    }
+
     fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
         let value = text.trim();
         let keyword = value.to_ascii_uppercase();

src/modules/insert/solid3d_cmds.rs

@@ -1862,6 +1862,21 @@ impl CadCommand for SweepCommand {
         matches!(self.step, SweepStep::PickPath | SweepStep::ReferenceLength | SweepStep::NewLength)
     }
 
+    // The reference-scale prompts read a typed length, but they also accept
+    // keyword letters, so without this a value committed from the dynamic
+    // box (the only route on web, where the canvas — not the command line —
+    // holds keyboard focus) resolves into an in-plane point instead: at
+    // `ReferenceLength` the typed length is dropped and stored as a stray
+    // first reference pick, at `NewLength` the scale is computed from the
+    // distance of that arbitrary point to the length anchor. `on_text_input`
+    // parses the same strings the command-line path would (keywords and
+    // `parse_typed_length`), so both entry routes behave identically (#1082).
+    // PickPath stays a point step: its letters are option keywords and its
+    // picks are path entities.
+    fn dyn_commit_as_text(&self) -> bool {
+        matches!(self.step, SweepStep::ReferenceLength | SweepStep::NewLength)
+    }
+
     fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
         let value = text.trim();
         if value.is_empty() {

src/modules/model/cylinder_cmd.rs

@@ -779,6 +779,18 @@ impl CadCommand for CylinderCommand {
             _ => None,
         }
     }
+
+    // The Height step's dynamic box is a span along the base-plane normal,
+    // not a point in the drawing plane. Without this, a typed value committed
+    // from the box (the only route on web, where the canvas — not the command
+    // line — holds keyboard focus) is resolved into an in-plane point whose
+    // height projects to ~0 and `commit_height` silently re-prompts.
+    // `on_text_input` parses the same string the command-line path would
+    // (keywords and `parse_typed_length`), so both entry routes behave
+    // identically (#1082).
+    fn dyn_commit_as_text(&self) -> bool {
+        matches!(self.step, Step::Height)
+    }
 }
 
 fn push_break(points: &mut Vec<[f32; 3]>) {

src/modules/model/primitive_cmd.rs

@@ -3405,6 +3405,33 @@ impl CadCommand for PrimitiveCommand {
         }
         self.height_step.then(|| self.cursor_height(cursor))
     }
+
+    // The height prompts' dynamic boxes are spans along the working-plane
+    // normal, not points in the drawing plane. These steps accept keyword
+    // letters (2Point / Axis endpoint / Top radius), so without this a typed
+    // value committed from the box (the only route on web, where the canvas —
+    // not the command line — holds keyboard focus) is resolved into an
+    // in-plane point whose height projects to ~0 and the commit is silently
+    // dropped with a re-prompt. `on_text_input` parses the same string the
+    // command-line path would (keywords and `parse_typed_length`), so both
+    // entry routes behave identically (#1082). BOX and WEDGE share
+    // `BoxStep::Height`; the 2Point/AxisEndpoint sub-steps keep committing
+    // as points, and SPHERE/TORUS radius steps type digits as in-plane
+    // distances by design.
+    fn dyn_commit_as_text(&self) -> bool {
+        match self.shape {
+            Shape::Cone => matches!(
+                self.cone_step,
+                ConeStep::Height | ConeStep::HeightAfterTopRadius
+            ),
+            Shape::Pyramid => matches!(
+                self.pyramid_step,
+                PyramidStep::Height | PyramidStep::HeightAfterTopRadius
+            ),
+            Shape::Box | Shape::Wedge => self.box_step == BoxStep::Height,
+            _ => false,
+        }
+    }
 }
 
 // ── Footprint preview ───────────────────────────────────────────────────────

src/scene/model/mesh_model.rs

@@ -10,37 +10,96 @@ use super::wire_model::WireModel;
 /// of the mesh converters' `SNAP_TABLE_MAX_VERTICES`: a mesh dense enough to
 /// exceed this has edges far too close together to pick apart at snap
 /// aperture size, and duplicating them into the wire set would cost more
-/// memory than the whole rest of the interaction set.
+/// memory than the whole rest of the interaction set. The builder budgets
+/// SEGMENTS against this (each costs two endpoints plus a NaN separator) and
+/// decimates rather than dropping when it is exceeded.
 pub const SNAP_EDGE_WIRE_MAX_POINTS: usize = 100_000;
 
+/// Segment budget implied by [`SNAP_EDGE_WIRE_MAX_POINTS`]: S segments cost
+/// `3·S − 1` wire points (two endpoints each plus a NaN separator between
+/// neighbours), so the point cap admits at most `(cap + 1) / 3` segments.
+const MAX_EDGE_SEGMENTS: usize = (SNAP_EDGE_WIRE_MAX_POINTS + 1) / 3;
+
+/// Halve `kept` in place, retaining every second segment (indices 0, 2, …).
+fn halve_kept_segments(kept: &mut Vec<([f64; 3], [f64; 3])>) {
+    let mut write = 0;
+    for read in (0..kept.len()).step_by(2) {
+        kept[write] = kept[read];
+        write += 1;
+    }
+    kept.truncate(write);
+}
+
 /// Build the interaction-only edge wire shared by every volume entity
 /// (3D solids, regions, bodies, surfaces, plain meshes).
 ///
 /// `pairs` yields one `(a, b)` world-space segment per edge. The wire carries
 /// the segments as NaN-separated point pairs (so `points` never chains two
-/// unrelated edges together) plus the same pairs in `key_vertices` (so
-/// Endpoint/Midpoint snap sees every true edge end / edge middle, not the
-/// ends of an artificial chain). It is `display_visible: false` /
-/// `plot_visible: false`: the mesh pipeline already draws these edges, the
-/// wire exists so the SNAPPER and the proximity pick see them exactly like
-/// any 2-D entity's geometry (#1030).
+/// unrelated edges together) plus the same NaN-separated pairs in
+/// `key_vertices` (so Endpoint/Midpoint snap sees every true edge end / edge
+/// middle, not the ends of an artificial chain between unrelated edges —
+/// Midpoint consumers treat consecutive `key_vertices` as one segment). It is
+/// `display_visible: false` / `plot_visible: false`: the mesh pipeline
+/// already draws these edges, the wire exists so the SNAPPER and the
+/// proximity pick see them exactly like any 2-D entity's geometry (#1030).
 ///
-/// Returns `None` when the edge count exceeds [`SNAP_EDGE_WIRE_MAX_POINTS`].
+/// Past [`MAX_EDGE_SEGMENTS`] the wire is not dropped but DECIMATED: the
+/// segment pairs are uniformly subsampled (every Nth, N a power of two, with
+/// the first and last segments always retained) down to the budget. Dropping
+/// the wire outright used to cost dense meshes ALL endpoint snap; decimation
+/// keeps partial coverage at the same bounded memory. The tradeoff: mid-wire
+/// edges thin out (their Midpoint/Nearest coverage becomes sparser) while
+/// both ends of the mesh stay snap-reachable.
+///
+/// Returns `None` only when `pairs` yields no segments at all.
 pub fn edge_snap_wire(
     name: String,
     color: [f32; 4],
     selected: bool,
     pairs: impl Iterator<Item = ([f64; 3], [f64; 3])>,
 ) -> Option<WireModel> {
-    let mut points: Vec<[f32; 3]> = Vec::new();
-    let mut points_low: Vec<[f32; 3]> = Vec::new();
-    let mut key_vertices: Vec<[f64; 3]> = Vec::new();
+    // ── Segment selection with bounded memory ─────────────────────────────
+    // Stream the pairs and keep at most MAX_EDGE_SEGMENTS of them: whenever
+    // the kept buffer fills, halve it and double the stride. That is uniform
+    // "every Nth" subsampling (power-of-two N) without ever buffering more
+    // than the budget — a runaway mesh costs O(cap) here, not O(edges), and
+    // its (already resident) tessellation is never duplicated.
+    let mut kept: Vec<([f64; 3], [f64; 3])> = Vec::new();
+    let mut stride = 1usize;
+    let mut total = 0usize;
+    let mut last_pair: Option<([f64; 3], [f64; 3])> = None;
+    for pair in pairs {
+        if total % stride == 0 {
+            if kept.len() >= MAX_EDGE_SEGMENTS {
+                halve_kept_segments(&mut kept);
+                stride *= 2;
+            }
+            kept.push(pair);
+        }
+        last_pair = Some(pair);
+        total += 1;
+    }
+    // Force-retain the final segment so decimation never removes the far end
+    // of the mesh: `(total - 1) % stride != 0` proves it is not already kept
+    // (every kept entry sits at an index that is a multiple of `stride`).
+    if let Some(last) = last_pair {
+        if (total - 1) % stride != 0 {
+            if kept.len() >= MAX_EDGE_SEGMENTS {
+                halve_kept_segments(&mut kept);
+            }
+            kept.push(last);
+        }
+    }
+
+    let mut points: Vec<[f32; 3]> = Vec::with_capacity(kept.len().saturating_mul(3));
+    let mut points_low: Vec<[f32; 3]> = Vec::with_capacity(kept.len().saturating_mul(3));
+    let mut key_vertices: Vec<[f64; 3]> = Vec::with_capacity(kept.len().saturating_mul(3));
     let mut aabb = WireModel::UNBOUNDED_AABB;
-    let mut extend = |p: [f64; 3]| {
+    let extend = |p: [f64; 3], aabb: &mut [f32; 4]| {
         let (x, y) = (p[0] as f32, p[1] as f32);
         if x.is_finite() && y.is_finite() {
-            if aabb == WireModel::UNBOUNDED_AABB {
-                aabb = [x, y, x, y];
+            if *aabb == WireModel::UNBOUNDED_AABB {
+                *aabb = [x, y, x, y];
             } else {
                 aabb[0] = aabb[0].min(x);
                 aabb[1] = aabb[1].min(y);
@@ -49,16 +108,14 @@ pub fn edge_snap_wire(
             }
         }
     };
-    for (a, b) in pairs {
-        if points.len() + 2 > SNAP_EDGE_WIRE_MAX_POINTS {
-            return None;
-        }
-        if !points.is_empty() {
+    for (index, (a, b)) in kept.into_iter().enumerate() {
+        if index > 0 {
             points.push([f32::NAN; 3]);
             points_low.push([0.0; 3]);
-            if points.len() + 2 > SNAP_EDGE_WIRE_MAX_POINTS {
-                return None;
-            }
+            // Mirrors `points`: without this separator Midpoint would pair
+            // the last vertex of one edge with the first vertex of the next
+            // and fabricate a floating midpoint between unrelated edges.
+            key_vertices.push([f64::NAN; 3]);
         }
         for p in [a, b] {
             let (hx, lx) = WireModel::split_ds(p[0]);
@@ -67,7 +124,7 @@ pub fn edge_snap_wire(
             points.push([hx, hy, hz]);
             points_low.push([lx, ly, lz]);
             key_vertices.push(p);
-            extend(p);
+            extend(p, &mut aabb);
         }
     }
     if points.is_empty() {

src/scene/model/solid_model.rs

@@ -273,7 +273,8 @@ pub fn edge_wires(body: &Body) -> Vec<acadrust::entities::Wire> {
 /// (`Solid3D::wires` and friends — pre-computed B-rep edge chains, also set
 /// on the temporary live-section entity). Each chain contributes its
 /// consecutive point pairs as snap segments (#1030). Returns `None` when the
-/// chains carry no usable segments or exceed the shared snap-wire point cap.
+/// chains carry no usable segments; past the shared snap-wire point cap
+/// `edge_snap_wire` decimates instead of dropping.
 pub fn entity_edge_snap_wire(
     chains: &[acadrust::entities::Wire],
     name: String,

src/snap.rs

@@ -2491,37 +2491,64 @@ fn wire_plane(wire: &WireModel) -> Option<WirePlane> {
     Some(WirePlane { origin, axis_x, axis_y, normal: axis_x.cross(axis_y).normalize() })
 }
 
-/// The f64 endpoints behind a `TangentGeom::Line`. The geom itself stores
-/// f32, which quantises survey-scale coordinates by centimetres; the wire's
-/// tessellation points (a double-single pair) hold the same vertices in full
-/// precision, so when a consecutive point pair matches the geom, use it.
-fn line_geom_endpoints_f64(wire: &WireModel, p1: [f32; 3], p2: [f32; 3]) -> (DVec3, DVec3) {
-    if wire.points.len() == 2 {
-        return (wp_f64(wire, 0), wp_f64(wire, 1));
-    }
-    let f32_pair = (Vec3::from_array(p1).as_dvec3(), Vec3::from_array(p2).as_dvec3());
-    // The f64 pair matches the geom's own segment when it sits within the
-    // f32 cast's rounding error (≤ 0.5 ulp of the coordinate magnitude).
-    // Take the CLOSEST pair, not the first within tolerance: adjacent
-    // polyline vertices can sit closer together than the quantisation at
-    // survey scale, and a first-match scan would then grab a neighbour's
-    // segment.
-    let mag = p1.iter().chain(p2.iter()).fold(0.0f32, |m, c| m.max(c.abs()));
-    let tol = (mag * f32::EPSILON) as f64 + 1e-9;
-    let mut best: Option<(f64, DVec3, DVec3)> = None;
+/// Lookup key for [`line_endpoint_map`]: the f32 bit patterns of the six
+/// endpoint coordinates with the two lowest mantissa bits cleared (a ~4-ulp
+/// grid). The geom's stored f32 and the f32 cast of the wire's double-single
+/// reconstruction sit within an ulp of each other, so both quantise into the
+/// same bucket; distinct segments only collide when they share an endpoint
+/// to well below snap distinguishability.
+type LineGeomKey = ([u32; 3], [u32; 3]);
+
+fn line_geom_key(p1: [f32; 3], p2: [f32; 3]) -> LineGeomKey {
+    const MASK: u32 = !0b11;
+    let quantise =
+        |p: [f32; 3]| [p[0].to_bits() & MASK, p[1].to_bits() & MASK, p[2].to_bits() & MASK];
+    (quantise(p1), quantise(p2))
+}
+
+/// One-shot map from a `TangentGeom::Line`'s quantised f32 endpoint pair to
+/// the wire's full-precision f64 pair behind it, so every Line geom of the
+/// wire resolves with an O(1) lookup instead of rescanning the whole
+/// tessellation per geom (which made `curves_in_frame` O(points × geoms) for
+/// every wire pair on every snap). First-wins on quantisation collisions:
+/// adjacent vertices closer than the grid are indistinguishable at snap
+/// scale anyway.
+fn line_endpoint_map(wire: &WireModel) -> HashMap<LineGeomKey, (DVec3, DVec3)> {
+    let mut map =
+        HashMap::with_capacity_and_hasher(wire.points.len() / 2 + 1, Default::default());
     for index in 0..wire.points.len().saturating_sub(1) {
         let a = wp_f64(wire, index);
         let b = wp_f64(wire, index + 1);
-        // NaN separators split runs; either side being NaN never matches.
+        // NaN separators split runs; neither side of them can match a geom.
         if !a.is_finite() || !b.is_finite() {
             continue;
         }
-        let miss = (a - f32_pair.0).length_squared() + (b - f32_pair.1).length_squared();
-        if miss <= 4.0 * tol * tol && best.map_or(true, |(m, _, _)| miss < m) {
-            best = Some((miss, a, b));
-        }
+        let key = line_geom_key(a.as_vec3().to_array(), b.as_vec3().to_array());
+        map.entry(key).or_insert((a, b));
     }
-    best.map(|(_, a, b)| (a, b)).unwrap_or(f32_pair)
+    map
+}
+
+/// The f64 endpoints behind a `TangentGeom::Line`. The geom itself stores
+/// f32, which quantises survey-scale coordinates by centimetres; the wire's
+/// tessellation points (a double-single pair) hold the same vertices in full
+/// precision, so resolve the geom through [`line_endpoint_map`] (built once
+/// per wire by the caller). A geom that misses the map falls back to its own
+/// f32 pair widened — exactly the no-match behaviour of the scan this
+/// replaced.
+fn line_geom_endpoints_f64(
+    wire: &WireModel,
+    p1: [f32; 3],
+    p2: [f32; 3],
+    endpoints: &HashMap<LineGeomKey, (DVec3, DVec3)>,
+) -> (DVec3, DVec3) {
+    if wire.points.len() == 2 {
+        return (wp_f64(wire, 0), wp_f64(wire, 1));
+    }
+    endpoints
+        .get(&line_geom_key(p1, p2))
+        .copied()
+        .unwrap_or((Vec3::from_array(p1).as_dvec3(), Vec3::from_array(p2).as_dvec3()))
 }
 
 /// Decompose a wire into its analytic curves inside `frame`.
@@ -2549,10 +2576,14 @@ fn curves_in_frame(wire: &WireModel, frame: &WirePlane, tol: f64) -> Option<Vec<
     };
 
     let mut curves = Vec::with_capacity(wire.tangent_geoms.len());
+    // Built on the FIRST Line geom and shared by every geom of this wire:
+    // one O(points) pass instead of an O(points) scan per Line geom.
+    let mut line_endpoints: Option<HashMap<LineGeomKey, (DVec3, DVec3)>> = None;
     for geom in &wire.tangent_geoms {
         let curve = match geom {
             TangentGeom::Line { p1, p2 } => {
-                let (p1, p2) = line_geom_endpoints_f64(wire, *p1, *p2);
+                let endpoints = line_endpoints.get_or_insert_with(|| line_endpoint_map(wire));
+                let (p1, p2) = line_geom_endpoints_f64(wire, *p1, *p2, endpoints);
                 (frame.contains(p1, tol) && frame.contains(p2, tol)).then(|| {
                     let (start, end) = (frame.to_2d(p1), frame.to_2d(p2));
                     // A crossing can sit exactly on a segment endpoint (the
@@ -2668,6 +2699,9 @@ fn exact_curve_intersections(wire_a: &WireModel, wire_b: &WireModel) -> Option<V
         return None;
     }
 
+    // NOTE: the nominal 1e-9 request is dominated by PLANE_TOL —
+    // `max(1e-9, PLANE_TOL)` is effectively 1e-7 here, matching the plane
+    // membership tolerance the frame reduction above already applied.
     let tolerance = cadkernel::geom2d::Tolerance::new(1e-9_f64.max(PLANE_TOL));
     let linear = tolerance.linear();
     let mut points: Vec<DVec3> = Vec::new();
@@ -4259,6 +4293,11 @@ mod ext_tests {
         ];
         let wire =
             entity_edge_snap_wire(&chains, "42".to_owned(), [0.8, 0.8, 0.85, 1.0]).expect("wire");
+        // Segment pairs stay NaN-separated across CHAIN junctions too (3 + 3
+        // + 1 = 7 pairs → 6 separators), so Midpoint never pairs the last
+        // vertex of one chain with the first vertex of the next.
+        let separators = wire.key_vertices.iter().filter(|p| !p[0].is_finite()).count();
+        assert_eq!(separators, 6);
         let wires = [wire];
         let mut snapper = Snapper::default();
         snapper.snap_enabled = true;
@@ -4283,24 +4322,107 @@ mod ext_tests {
         );
     }
 
-    #[test]
-    fn edge_snap_wire_caps_runaway_meshes() {
-        use crate::scene::model::mesh_model::{edge_snap_wire, SNAP_EDGE_WIRE_MAX_POINTS};
-        let segment = ([0.0, 0.0, 0.0], [1.0, 0.0, 0.0]);
-        // Each pair costs up to 3 points (2 endpoints + a NaN separator), so
-        // a third of the cap fits and the full cap must not.
-        let pairs = std::iter::repeat(segment).take(SNAP_EDGE_WIRE_MAX_POINTS / 3);
-        assert!(edge_snap_wire("ok".into(), [1.0; 4], false, pairs).is_some());
-        let pairs = std::iter::repeat(segment).take(SNAP_EDGE_WIRE_MAX_POINTS);
+    /// Inverse of [`snap_one`]: the same camera scaffolding, asserting that
+    /// nothing snap-enabled lands anywhere near `near`.
+    fn snap_none(snapper: &mut Snapper, wires: &[WireModel], near: DVec3) {
+        // Zoomed out: 1 world unit ≈ 5 px, same as `snap_one`.
+        let view_rot = Mat4::from_scale(Vec3::splat(0.01));
+        let bounds = Rectangle {
+            x: 0.0,
+            y: 0.0,
+            width: 1000.0,
+            height: 1000.0,
+        };
+        let eye = DVec3::new(near.x, near.y, 500.0);
+        let cursor_screen = world_to_screen(near, view_rot, eye, bounds);
+        let res = snapper.snap(
+            near, cursor_screen, wires, view_rot, eye, bounds, Vec3::ZERO,
+            (Vec3::X, Vec3::Y, Vec3::Z), None,
+        );
         assert!(
-            edge_snap_wire("too big".into(), [1.0; 4], false, pairs).is_none(),
-            "meshes past the point cap must ship no snap wire"
+            res.is_none(),
+            "nothing must snap near {near:?}, got {:?}",
+            res.map(|r| (r.snap_type, r.world))
         );
     }
 
+    #[test]
+    fn edge_snap_wire_disjoint_edges_have_no_phantom_midpoint() {
+        use crate::scene::model::mesh_model::edge_snap_wire;
+        // Two DISJOINT triangles 10 units apart, fed exactly like
+        // `MeshLodSet::snap_edge_wire` feeds `edge_snap_wire` (three segment
+        // pairs per triangle).
+        let triangle = |ox: f64| {
+            let a = [ox, 0.0, 0.0];
+            let b = [ox + 1.0, 0.0, 0.0];
+            let c = [ox + 0.5, 1.0, 0.0];
+            [(a, b), (b, c), (c, a)]
+        };
+        let pairs = triangle(0.0).into_iter().chain(triangle(10.0));
+        let wire = edge_snap_wire("t".into(), [1.0; 4], false, pairs).expect("wire");
+        // `key_vertices` must separate the segment pairs with NaN exactly
+        // like `points` does. Without the separators, every Midpoint consumer
+        // pairs the LAST vertex of one edge with the FIRST vertex of the next
+        // — here triangle 0's (0,0,0) with triangle 10's (10,0,0) — and
+        // fabricates a floating midpoint between unrelated edges.
+        let separators = wire.key_vertices.iter().filter(|p| !p[0].is_finite()).count();
+        assert_eq!(separators, 5, "one NaN separator between each of the 6 pairs");
+
+        let wires = [wire];
+        let mut snapper = Snapper::default();
+        snapper.snap_enabled = true;
+        snapper.enabled = [SnapType::Midpoint].into_iter().collect();
+        // The junction's phantom midpoint would sit at (5, 0, 0); the nearest
+        // true midpoint is ~4.3 world units away, far outside the aperture.
+        snap_none(&mut snapper, &wires, DVec3::new(5.0, 0.0, 0.0));
+        // Sanity: a true edge midpoint still snaps through key_vertices.
+        snap_one(
+            &mut snapper,
+            &wires,
+            DVec3::new(0.6, 0.05, 0.0),
+            SnapType::Midpoint,
+            DVec3::new(0.5, 0.0, 0.0),
+        );
+    }
+
+    #[test]
+    fn edge_snap_wire_caps_runaway_meshes() {
+        use crate::scene::model::mesh_model::{edge_snap_wire, SNAP_EDGE_WIRE_MAX_POINTS};
+        let segment = |i: usize| ([i as f64, 0.0, 0.0], [(i + 1) as f64, 0.0, 0.0]);
+        let segment_count = |wire: &WireModel| {
+            // One NaN separator between neighbouring pairs → runs − 1.
+            wire.points.iter().filter(|p| !p[0].is_finite()).count() + 1
+        };
+        // Each pair costs up to 3 points (2 endpoints + a NaN separator), so
+        // a third of the point cap in SEGMENTS fits without decimation.
+        let fitting = SNAP_EDGE_WIRE_MAX_POINTS / 3;
+        let wire = edge_snap_wire("ok".into(), [1.0; 4], false, (0..fitting).map(segment))
+            .expect("wire at the segment budget");
+        assert_eq!(segment_count(&wire), fitting);
+        assert!(wire.points.len() <= SNAP_EDGE_WIRE_MAX_POINTS);
+
+        // Past the budget the wire is DECIMATED, not dropped: the segment
+        // pairs are uniformly subsampled down to the budget so dense meshes
+        // keep (partial) endpoint coverage instead of losing their edge wire
+        // — and with it all endpoint snap — entirely.
+        let total = SNAP_EDGE_WIRE_MAX_POINTS; // 3x the segment budget
+        let wire = edge_snap_wire("decimated".into(), [1.0; 4], false, (0..total).map(segment))
+            .expect("over-cap mesh must still ship a decimated snap wire");
+        let kept = segment_count(&wire);
+        assert!(kept < total, "over-cap wire must be decimated, kept {kept}");
+        assert!(
+            wire.points.len() <= SNAP_EDGE_WIRE_MAX_POINTS,
+            "decimated wire must honour the point cap ({} points)",
+            wire.points.len()
+        );
+        // The first and last source segments survive decimation, so both ends
+        // of the mesh stay endpoint-snappable.
+        assert!(wire.key_vertices.contains(&[0.0, 0.0, 0.0]));
+        assert!(wire.key_vertices.contains(&[total as f64, 0.0, 0.0]));
+    }
+
     #[test]
     fn scene_solid_with_mesh_cache_snaps_endpoint_midpoint_nearest() {
-        use crate::scene::model::mesh_model::MeshLodSet;
         use crate::scene::Scene;
         use acadrust::entities::Solid3D;
 

src/ui/overlay.rs

@@ -567,12 +567,6 @@ pub struct GridCanvasState {
     pub cache: canvas::Cache<iced::Renderer>,
 }
 
-/// Compute the adaptive grid step size (world units) from camera zoom.
-///
-/// Returns the smallest power-of-5 multiple of 1.0 that places grid lines at
-/// least `MIN_GRID_PX` pixels apart at the camera pivot. Both orthographic and
-/// perspective cameras have the same vertical scale there. Camera rotation is
-/// intentionally absent so orbiting cannot rescale the visible grid or snap.
 /// Perpendicular screen distance (px) from `p` to the infinite line through
 /// `a` and `b`. Degenerate (`a`≈`b`) falls back to the point distance. Used
 /// to tell whether a tracking vector really passes through the locked cursor
@@ -632,6 +626,12 @@ fn clip_seg(p0: Point, p1: Point, bounds: iced::Rectangle) -> Option<(Point, Poi
     ))
 }
 
+/// Compute the adaptive grid step size (world units) from camera zoom.
+///
+/// Returns the smallest power-of-5 multiple of 1.0 that places grid lines at
+/// least `MIN_GRID_PX` pixels apart at the camera pivot. Both orthographic and
+/// perspective cameras have the same vertical scale there. Camera rotation is
+/// intentionally absent so orbiting cannot rescale the visible grid or snap.
 pub fn compute_grid_step(distance: f32, fov_y: f32, bounds: iced::Rectangle) -> f32 {
     let half_height = distance * (fov_y * 0.5).tan();
     if !half_height.is_finite() || half_height <= 1e-9 || bounds.height <= 0.0 {

tests/pdf_size_repro.rs

@@ -11,6 +11,7 @@
 use OpenCADStudio::io::pdf_export::{
     render_pdf_bytes, PdfPageInput, PdfPlotOptions, PlotContent, PlotWire,
 };
+use OpenCADStudio::io::plot_style::{LW_TABLE, PlotStyleTable};
 use OpenCADStudio::scene::model::hatch_model::{HatchModel, HatchPattern, PatFamily};
 use OpenCADStudio::scene::pipeline::text_gpu::push_glyph_vertices;
 use OpenCADStudio::scene::text::glyph_quads::layout_glyph_quads;
@@ -153,6 +154,82 @@ fn stroke_text_page_size_is_bounded() {
     );
 }
 
+/// Heavy-pen (CTB lineweight override) leg: an absolute pen is arbitrary pt and
+/// can exceed the glyph Form XObject /BBox's 1.5-unit SDF spread margin
+/// (2.5 mm text + 1.0 mm pen → 1.79-unit half-width), squaring round caps off
+/// at the tile edge. Heavy-pen entities must bypass the Forms and stroke
+/// directly in page space, while the default-pen export of the same page keeps
+/// its Form replay (and size class).
+#[test]
+fn heavy_pen_text_bypasses_forms_and_light_pen_sizes_hold() {
+    let heavy_ctb = {
+        let mut ctb = PlotStyleTable::identity("heavy-pen.ctb");
+        let one_mm = LW_TABLE.iter().position(|&mm| mm == 1.0).unwrap() as u8;
+        let entry = &mut ctb.aci_entries[1];
+        entry.lineweight = one_mm;
+        entry.color = Some([0, 0, 0]);
+        ctb
+    };
+    // The same 200-entity stroke-text page as the bounded leg above, with the
+    // wires on ACI 1 so the CTB's 1.0 mm pen applies.
+    let wires: Vec<PlotWire> = (0..200)
+        .map(|i| {
+            let x = 10.0 + (i % 5) as f64 * 40.0;
+            let y = 10.0 + (i / 5) as f64 * 7.0;
+            let mut wire = text_wire(
+                "txt",
+                "DIMENSION TEXT 12345.6789 - TEXT ANNOTATION LINE",
+                [x, y, 0.0],
+                2.5,
+            );
+            wire.wire.aci = 1;
+            wire
+        })
+        .collect();
+    let glyph_quads: usize = wires.iter().map(|w| w.wire.text_verts.len() / 6).sum();
+    let page = a4_page(wires, Vec::new());
+
+    let heavy =
+        render_pdf_bytes(std::slice::from_ref(&page), Some(&heavy_ctb)).expect("heavy export");
+    println!(
+        "heavy-pen (1.0 mm CTB) stroke-text 200-entity A4 page: {} bytes for {} glyph quads",
+        heavy.len(),
+        glyph_quads
+    );
+    assert!(heavy.starts_with(b"%PDF"), "not a PDF");
+    assert!(
+        heavy.len() > 100_000,
+        "heavy-pen text page suspiciously small: {}",
+        heavy.len()
+    );
+    // The bypass engaged: zero glyph Form `/Do` replays in the heavy render.
+    // (Page content streams are uncompressed, so the operator is greppable.)
+    let do_count = |bytes: &[u8]| bytes.windows(3).filter(|w| w == b" Do").count();
+    assert_eq!(
+        do_count(&heavy),
+        0,
+        "heavy-pen glyphs still replay clipped Form XObjects"
+    );
+
+    // Light-pen regression fence: the same page without a plot style keeps
+    // every glyph on the Form path (one `/Do` per quad) and its size class.
+    let light = render_pdf_bytes(std::slice::from_ref(&page), None).expect("light export");
+    println!(
+        "same page without CTB: {} bytes ({} Form /Do replays)",
+        light.len(),
+        do_count(&light)
+    );
+    assert!(
+        do_count(&light) >= glyph_quads,
+        "Form glyph replay vanished from the light path"
+    );
+    assert!(
+        light.len() < 2_000_000,
+        "light-pen text page regressed to {} bytes",
+        light.len()
+    );
+}
+
 /// Pattern hatch + dense polyline comparison leg: identifies which content
 /// type dominates a mixed page. ANSI31-style 45° hatch over an A4-sized rect.
 #[test]