Add-ons: Path Precision Tools — Shared Edge Merge

Path Precision Tools gains the Shared Edge Merge Tool, kept out of the
toolbars (All Tools drawer and Object › Plug-ins › Path Precision Tools,
no shortcut), and Keep Shared Points Together:

- Shared Edge Merge Tool (sharedEdge): over two paths touching at two
  coincident anchors (tolerance 0 to 3 pt) hovering shows the two
  stretches and the merged edge; a click replaces both with it, half way
  between them, or following the upper (Shift) or lower (Alt) path. Both
  paths stay closed or open, anchors either stretch has inside are
  matched on the other, one undo step.
- Making ends: near anchors meet on a click and an anchor one path lacks
  is added to match; Shift+Alt asks for this inside a stretch.
- Keep Shared Points Together: an option that makes Slide Anchor Along
  Path, Extend Path and Set Anchor take coincident anchors along. Nothing
  else in the app changes.
- Shared Edges section in the Anchor Inspector: brush diameter,
  coincidence and the option.
- Commands addon.pathtools.mergeEdge and movePointsTogether, params
  validated and covered by the command sweep.
- Cursor stand-in, catalog rows in every language, docs and tests.

docs/mcp.md

@@ -5795,8 +5795,9 @@ type and evening out horizontal scales are not there yet.
 Path Precision Tools is a built-in add-on for exact anchor and path work: its commands are `addon.pathtools.*`, and in
 the desktop app it lives in Object › Plug-ins › Path Precision Tools, in its Anchor Inspector panel
 (`window.panel {panel: "anchorInspector"}`), in its Parametric Shape panel (`window.panel {panel: "parametricShape"}`)
-and in six tools that the toolbars don't show until they are added from the All Tools drawer (or chosen with
-`tool.select`): `anchorEraserBrush`, `extendPath`, `measureInspect`, `parametricShape`, `cornerTool` and `slideAnchor`.
+and in seven tools that the toolbars don't show until they are added from the All Tools drawer (or chosen with
+`tool.select`): `anchorEraserBrush`, `extendPath`, `measureInspect`, `parametricShape`, `cornerTool`, `slideAnchor` and
+`sharedEdge`.
 None has a shortcut. Each edit is one undo step, and an edit that changes nothing makes no step.
 
 Tools:
@@ -5833,6 +5834,16 @@ Tools:
   dragging: the anchor runs along the curve it sits on, as far as just short of its neighbours, and the two segments
   beside it are refitted. Shift snaps to where the path's tangent is at a multiple of 45° from the Constrain Angle. Ends
   of open paths don't slide.
+- **Shared Edge Merge Tool** (`sharedEdge`, or the UI command `addon.pathtools.sharedEdgeTool`, which also shows the
+  Anchor Inspector panel with its Shared Edges section): works on any two unlocked paths under its round brush, selected
+  or not. Where they touch at two coincident anchors, hovering shows the two stretches between those anchors dashed and
+  the edge replacing them solid (green when they are one edge already); a click runs `addon.pathtools.mergeEdge`, half
+  way between the two. Shift keeps the upper path's outline, Alt the lower's. Where the anchors aren't there yet a click
+  makes an end: two near anchors meet half way (or, with Shift or Alt, on the path kept), and an anchor only one path has
+  there gets a match on the other. Shift+Alt makes an end even inside a stretch that could merge. Stretches over 10%
+  different in length, or at over 120° at an end, are left alone. Options (`tool.setOption`, or the panel, kept with the
+  preferences): `diameter` (0.25 to 200 pt, 20), `tolerance` (how near two anchors count as coincident, 0 to 3 pt,
+  0.002) and `together` (Keep Shared Points Together).
 
 Commands:
 
@@ -5878,6 +5889,18 @@ Commands:
   so the outline stays (the anchor count and index stay). `t`, -0.98 to 0.98, says where: positive, a curve parameter on
   the segment after the anchor; negative, back from the end of the one before. An anchor at a sharp corner loses it, as
   the corner isn't on the way. → `{id, strayed}`, how far the outline moved in points.
+- `addon.pathtools.mergeEdge {a, b, at, diameter?, tolerance?, follow?, ends?}` looks within `diameter` (0.25 to 200 pt,
+  default 20) of `at` ([x, y]) on paths `a` and `b`, two editable paths: where they touch at two anchors coincident within
+  `tolerance` (0 to 3 pt, default 0.002), one each way along them, it replaces the stretches between with one edge;
+  otherwise it makes an end there, and `ends: true` asks for that first. `follow` says which outline stays: `average`
+  (default; half way between), `a` or `b`. Each path stays closed or open, and anchors either stretch has inside are on
+  the merged edge. One undo step. → `{a, b, made}`, with `made` `edge`, `end`, or `nothing` when they are merged already
+  (no undo step); it is an error if there is nothing to merge there.
+- `addon.pathtools.movePointsTogether {enabled?}` sets Keep Shared Points Together (without `enabled`, turns it the other
+  way). While it is on, anchors of any editable path coincident, within the Shared Edge Merge Tool's `tolerance`, with
+  one that `addon.pathtools.slideAnchor`, `extend` or `setAnchor` moves go with it, in the same undo step; an Extend Path
+  that adds an anchor leaves the old end, and what shares it, where they are. Nothing else in the app changes. It is the
+  `together` option of tool `sharedEdge`, off by default. → `{enabled}`.
 - `addon.pathtools.shape.create {center, kind?, width?, height?, rotation?, count?, a?, b?, radius?}` draws a parametric
   shape with the current paint, selected. `kind`: `rectangle`, `ellipse`, `polygon` (default), `star`, `ring`, `arrow`,
   `cross`, `heart`, `gear` or `bubble` (a speech bubble). `width` and `height` are 0.01 to 16,384 pt (100);

docs/target-app-parity.md

@@ -1,6 +1,6 @@
 # Parity with Adobe Illustrator
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-31 · **Change:** minor (supersampled raster exports avoid redundant compositing for opaque knockout fills; Path Precision Tools add-on: Corner Tool and Slide Anchor Along Path; scores unchanged) · **Target:** Adobe Illustrator 2026 (30.x; public release notes through 30.7, August 2026)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-31 · **Change:** minor (Path Precision Tools add-on: Shared Edge Merge Tool; scores unchanged) · **Target:** Adobe Illustrator 2026 (30.x; public release notes through 30.7, August 2026)
 
 ## Feature submission evidence
 
@@ -1289,6 +1289,20 @@ and `addons::slide_anchor` in `vectorcraft-tools`, `cmd::addons::pathtools::test
 one undo step, bad params refused, the tools' gestures), `addons::pathtools::tests` in `vectorcraft-ui-egui` (submenu,
 panel section), `edit_toolbar::tests` and `command_sweep`.
 
+The add-on's Shared Edge Merge Tool (2026-10-31) works on any two editable paths under its round brush. Where they touch
+at two coincident anchors (tolerance 0 to 3 pt), hovering shows both stretches and the merged edge, and a click replaces
+both with it, half way between them, or following the upper (Shift) or lower (Alt) path; anchors either stretch has inside
+are matched on the other, both paths stay closed or open, and it is one undo step. Near anchors meet on a click and an
+anchor one path lacks is added to match. Keep Shared Points Together, an option in the Anchor Inspector, makes Slide Anchor
+Along Path, Extend Path and Set Anchor take coincident anchors along; nothing else in the app changes. Commands
+`addon.pathtools.mergeEdge` and `movePointsTogether`; `vectorcraft_pathops::addons::pathtools::apply_merge`. Not yet:
+growing to adjacent stretches, preview preferences, cycling three candidates, pairs at crossings without anchors, the
+tool's Alt-click cut and delete, and shared segments reshaping together. Tests: `addons::pathtools::shared_edge` in
+`vectorcraft-pathops` (the merged edge lies half way, topology, unequal anchors, stretches over a closed path's start,
+ends), `addons::shared_edge` in `vectorcraft-tools`, `cmd::addons::pathtools::shared_edge::tests` in `vectorcraft-engine`
+(one undo step, bad params refused, the tool's click, the option), `addons::pathtools::tests` in `vectorcraft-ui-egui`
+(submenu, panel section), `edit_toolbar::tests` and `command_sweep`.
+
 ## Smart Pen add-on (2026-10-30)
 
 A VectorCraft addition, not an Illustrator feature, so no area score moves. Object › Plug-ins › Smart Pen selects the
@@ -1338,6 +1352,7 @@ add-on.
 | Date | Change | Summary |
 |---|---|---|
 | 2026-10-30 | minor | File formats: `.ai`/EPS editing data: a blend takes the transparency (opacity, blend mode, knockout) in its state block after its record, so its steps knock each other out as the page draws them; a user's file comes in 0.6% from its page instead of 1.3%. Scores and estimates unchanged. |
+| 2026-10-31 | minor | Path Precision Tools add-on: the Shared Edge Merge Tool and Keep Shared Points Together; evidence added; scores unchanged. |
 | 2026-10-31 | minor | Path Precision Tools add-on: the Corner Tool and Slide Anchor Along Path; evidence added; scores unchanged. |
 | 2026-10-30 | patch | Performance: opaque solid-fill knockout paths avoid redundant erase/add compositing in hard-edge frames, including supersampled raster export; analytical antialiasing keeps its existing rounding; scores and estimates unchanged |
 | 2026-10-30 | minor | File formats: `.ai`/EPS editing-data fidelity from an audit of a user's files: All Caps and Small Caps (#4708); placed files at their box's corner, kept where they draw closer to the page (#4664, #4723, #4742); pages cropped to the art, with `UserUnit` (#4658, #4727); gradient mesh corners with handle weights of 0 and the state written after a mesh (#4738, #4744, #4748); type on a path spaced as the file lays it out (#4743); synthetic regressions in `crates/eps`; evidence added; scores unchanged. |

docs/ui-parity.md

@@ -1,6 +1,6 @@
 # UI and interaction parity
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-31 · **Change:** minor (Path Precision Tools add-on: live Path Effects; scores unchanged) · **Target:** Adobe Illustrator 2026 (30.x)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-31 · **Change:** minor (Path Precision Tools add-on: Shared Edge Merge Tool; scores unchanged) · **Target:** Adobe Illustrator 2026 (30.x)
 
 ## Feature submission evidence
 
@@ -326,6 +326,7 @@ next unit in the order a right-click on a ruler lists them, from Feet back to Po
 | Tabs panel: a stop drags from where the press landed, a stop just added included | done | #1458 |
 | Outline view keeps template layers in Preview, dimmed | done | #1486; a picture placed to be traced stays visible under the outlines |
 | Smart Pen add-on (VectorCraft addition): Object › Plug-ins › Smart Pen selects the Smart Pen Tool, which the All Tools drawer lists under its own heading but neither toolbar shows as shipped (no shortcut), and opens the Smart Pen panel (next segment straight or curved; Remove Points Keep Shape, Make Smooth, Make Corner, Retract Handles, Close or Join). The tool draws (click: straight or curved segment, a curve after a straight one tangent; drag: smooth anchor, Alt breaks the handle, Shift 45°, Space moves it; Tab switches a segment; rubber band; close, join, continue) and edits without switching tools (click selects a point, drag moves it, Alt-click removes it keeping the shape, Shift+Alt-click deletes it, double-click toggles smooth/corner; handle drags with Shift and Alt; segment drags reshape, Alt-click adds a point) | done | `addon.pen.*`, `crates/tools/src/addons/smart_pen.rs`, `crates/ui-egui/src/addons/pen.rs` and their tests; not an Illustrator feature, so it is not scored |
+| Path Precision Tools add-on (VectorCraft addition): Object › Plug-ins › Path Precision Tools selects its seven tools (Anchor Eraser Brush, Extend Path, Measure & Inspect, Parametric Shape, Corner Tool, Slide Anchor Along Path, Shared Edge Merge Tool), which the All Tools drawer lists under their own heading but neither toolbar shows as shipped, opens the Anchor Inspector panel (the selected anchor's X/Y and handle lengths and angles as fields; Make Smooth, Make Corner, Equalize Handles, Remove Points Keep Shape, Add Points, the three ways to close) and the Parametric Shape panel (kind, count, W/H, rotation, the kind's own values and corner radius of the selected parametric shape, or of the tool's next one), and runs Add Points at / Split at Crossings and Convert to Parametric Shape; the Parametric Shape Tool draws ten re-editable kinds from the centre (↑/↓ and ←/→ change their numbers while dragging) and edits a selected one with handles; the Corner Tool cuts editable corners on any path (hover shows the anchor, a click uses its radius and kind, a drag sizes the corner, Shift whole values; a corner's marker selects it and loads its values, drags to resize, to 0 or double-clicked removes it; never past what fits; Alt-marquee cuts every anchor inside) with a Corners section in the Anchor Inspector (radius, kind, selected count, Apply to Selected Anchors); Slide Anchor Along Path drags an anchor along its curve with the segments beside it refitted, Shift snapping where the tangent is a multiple of 45°; the Shared Edge Merge Tool shows, over two paths touching at two coincident anchors, the two stretches and the edge merging them, a click merges them (half way; Shift the upper path, Alt the lower), and near anchors meet or an anchor one path lacks is added to match (Shift+Alt asks for this inside a stretch), with a Shared Edges section in the Anchor Inspector (brush diameter, coincidence 0 to 3 pt, Keep Shared Points Together, which takes coincident anchors along with the add-on's own anchor moves); a double-click on the brush or Extend Path tool opens its options | done | `addon.pathtools.*`, `crates/tools/src/addons/`, `crates/ui-egui/src/addons/pathtools.rs`, `crates/ui-egui/src/addons/pathtools/` and their tests; not an Illustrator feature, so it is not scored |
 | Path Precision Tools add-on (VectorCraft addition): Effect › Path Effects lists its live effects (Dashes to Geometry, Add Anchors, Extend Path, Close Path, Smooth Anchors, Retract Handles, Reverse Direction, Simplify Anchors, Split at Anchors), each with the effect dialog's live Preview except Reverse Direction, which has no options, and listed in the Appearance panel like any effect | done | `addon.path.*`, `crates/effects/src/addons/path.rs`, `crates/ui-egui/src/addons/pathtools.rs` and their tests; not an Illustrator feature, so it is not scored |
 | Path Precision Tools add-on (VectorCraft addition): Object › Plug-ins › Path Precision Tools selects its four tools (Anchor Eraser Brush, Extend Path, Measure & Inspect, Parametric Shape), which the All Tools drawer lists under their own heading but neither toolbar shows as shipped, opens the Anchor Inspector panel (the selected anchor's X/Y and handle lengths and angles as fields; Make Smooth, Make Corner, Equalize Handles, Remove Points Keep Shape, Add Points, the three ways to close) and the Parametric Shape panel (kind, count, W/H, rotation, the kind's own values and corner radius of the selected parametric shape, or of the tool's next one), and runs Add Points at / Split at Crossings and Convert to Parametric Shape; the Parametric Shape Tool draws ten re-editable kinds from the centre (↑/↓ and ←/→ change their numbers while dragging) and edits a selected one with handles; a double-click on the brush or Extend Path tool opens its options | done | `addon.pathtools.*`, `crates/tools/src/addons/`, `crates/ui-egui/src/addons/pathtools.rs`, `crates/ui-egui/src/addons/pathtools/shape.rs` and their tests; not an Illustrator feature, so it is not scored |
 | Path Precision Tools add-on (VectorCraft addition): Object › Plug-ins › Path Precision Tools selects its six tools (Anchor Eraser Brush, Extend Path, Measure & Inspect, Parametric Shape, Corner Tool, Slide Anchor Along Path), which the All Tools drawer lists under their own heading but neither toolbar shows as shipped, opens the Anchor Inspector panel (the selected anchor's X/Y and handle lengths and angles as fields; Make Smooth, Make Corner, Equalize Handles, Remove Points Keep Shape, Add Points, the three ways to close) and the Parametric Shape panel (kind, count, W/H, rotation, the kind's own values and corner radius of the selected parametric shape, or of the tool's next one), and runs Add Points at / Split at Crossings and Convert to Parametric Shape; the Parametric Shape Tool draws ten re-editable kinds from the centre (↑/↓ and ←/→ change their numbers while dragging) and edits a selected one with handles; the Corner Tool cuts editable corners on any path (hover shows the anchor, a click uses its radius and kind, a drag sizes the corner, Shift whole values; a corner's marker selects it and loads its values, drags to resize, to 0 or double-clicked removes it; never past what fits; Alt-marquee cuts every anchor inside) with a Corners section in the Anchor Inspector (radius, kind, selected count, Apply to Selected Anchors); Slide Anchor Along Path drags an anchor along its curve with the segments beside it refitted, Shift snapping where the tangent is a multiple of 45°; a double-click on the brush or Extend Path tool opens its options | done | `addon.pathtools.*`, `crates/tools/src/addons/`, `crates/ui-egui/src/addons/pathtools.rs`, `crates/ui-egui/src/addons/pathtools/` and their tests; not an Illustrator feature, so it is not scored |
@@ -374,6 +375,7 @@ separate. Scores and hours unchanged. [Behavior and command details](development
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-31 | minor | Path Precision Tools add-on: the Shared Edge Merge Tool and Keep Shared Points Together; scores and estimates unchanged |
 | 2026-10-31 | minor | Path Precision Tools add-on: live Path Effects in Effect › Path Effects; scores and estimates unchanged |
 | 2026-10-31 | minor | Path Precision Tools add-on: the Corner Tool (editable corners, panel section) and Slide Anchor Along Path; scores and estimates unchanged |
 | 2026-10-31 | minor | Artwork Cleanup add-on (a VectorCraft addition): its text tools in the panel and Object › Plug-ins › Artwork Cleanup; scores and estimates unchanged |