Blend: a blend without a spine shows the Appearance widget

A blend made with Create Spine set to Never now shows the Appearance
widget with the Selection and Blend tools, so its color Shift can be
dragged on the canvas as on a blend with a spine. The Easing widget
stays hidden, since easing needs a spine.

The widget sits 16 px above the halfway point, by length, of the
straight lines between the key centers that the steps are laid out
along, and a drag follows those lines' direction there. The lines are
not drawn. `blend_layout_line` exposes that line; `blend_spine` still
returns `None` for such a blend.

docs/gaps.md

@@ -541,7 +541,7 @@ macOS cursor delivery (#2292) is narrowed to a native host adapter using the exi
   Ease Out In), Ramp 0–100% and independent color Shift; easing is disabled without a spine.
   The original polynomial distributions approximate the public description. With the Selection or
   Blend tool, on-canvas widgets on a blend with a spine set the color Shift and, when the steps follow
-  that spine, the Ramp; a blend made without a spine shows neither widget. The Blend panel shows the
+  that spine, the Ramp; a blend made without a spine shows the color Shift widget alone. The Blend panel shows the
   values they set. [Public source](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html).
 
 - **Done:** gradient Dither (30.0): the Gradient panel's Dither box (`paint.editGradient` `dither`, also in `paint.setFill`'s

docs/mcp.md

@@ -9769,8 +9769,9 @@ the Selection and Blend tools show the same values as widgets
 16 px above and below the spine's halfway point (where the boxes of three or more other visible objects hold that
 spot, a widget moves out in 16 px steps, up to 144 px, joined to the halfway point by a line): the upper one sets
 `colorShift` and the lower one, shown only when the steps follow the spine as `ramp` needs, sets `ramp`, by one per screen pixel dragged along the spine and by one per arrow key
-during the drag (ten with Shift). Each drag is one undo step, and `press_key` Escape or a switch to another tool
-during it puts the value back:
+during the drag (ten with Shift). A blend made without a spine shows the upper widget alone, placed against the
+straight lines between its key centers that its steps are laid out along, which are not drawn. Each drag is one undo
+step, and `press_key` Escape or a switch to another tool during it puts the value back:
 
 ```json
 {"name":"run_command","arguments":{"command":"object.blend.setEasing","params":{"id":40,"ramp":35}}}

docs/target-app-parity.md

@@ -1780,7 +1780,9 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
 
 - **Blend, mesh and envelope points by number:** `object.blend.spine.moveAnchor`, `reshapeSegment` and `removeAnchor`, `object.mesh.setPointColor`, `movePoint` and `deletePoint`, and `object.envelope.setMeshPoint` refuse an `anchor`, `segment` or `index` that is not a whole number, and `object.envelope.setMeshPoint` refuses a negative `index`. Specified Steps (`object.blend.make`, `object.blend.options`) and the rows and columns of `object.mesh.create`, `object.envelope.makeWithMesh` and `resetWithMesh` must be whole numbers too.
 
-- **Blend widgets on the canvas:** with one blend selected that has a spine, the Selection and Blend tools show two widgets 16 px above and below the spine's halfway point (further out, joined to that point by a line, where the boxes of three or more other objects crowd the spot), as the [Blend panel help page](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html) describes an upper widget for Appearance and a lower one for Easing. The upper one sets Shift and the lower one Ramp, keeping the Type, and the lower one shows only when the steps follow that spine; a blend made without a spine shows neither. A drag along the spine changes the value by one per screen pixel from its value at the press, the arrow keys during the drag by one (Shift: ten), and Escape or a tool switch cancels it. A drag is one undo step, or none when the value ends where it started. The placement, the drag and the keys are VectorCraft's own rules. `object.blend.setEasing` sets the same values for agents. Evidence: `blendwidget::tests`, `tests::blendopts::{set_easing_edits_one_blend_and_refuses_what_it_cannot_set, dragging_a_blend_widget_is_one_undo_step_and_a_click_or_escape_none}`, `shortcuts::tests::shift_arrows_step_a_pressed_blend_widget_by_ten`.
+- **Blend widgets on the canvas:** with one blend selected that has a spine, the Selection and Blend tools show two widgets 16 px above and below the spine's halfway point (further out, joined to that point by a line, where the boxes of three or more other objects crowd the spot), as the [Blend panel help page](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html) describes an upper widget for Appearance and a lower one for Easing. The upper one sets Shift and the lower one Ramp, keeping the Type, and the lower one shows only when the steps follow that spine. A drag along the spine changes the value by one per screen pixel from its value at the press, the arrow keys during the drag by one (Shift: ten), and Escape or a tool switch cancels it. A drag is one undo step, or none when the value ends where it started. The placement, the drag and the keys are VectorCraft's own rules. `object.blend.setEasing` sets the same values for agents. Evidence: `blendwidget::tests`, `tests::blendopts::{set_easing_edits_one_blend_and_refuses_what_it_cannot_set, dragging_a_blend_widget_is_one_undo_step_and_a_click_or_escape_none}`, `shortcuts::tests::shift_arrows_step_a_pressed_blend_widget_by_ten`.
+
+- **Blend widgets without a spine:** a blend made with Create Spine set to Never shows the Appearance widget alone with the Selection and Blend tools, and its drag sets Shift as on a blend with a spine; there is no Easing widget, as the [Blend panel help page](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html) makes Easing available only on a blend with a spine. The widget sits 16 px above the halfway point, by length, of the straight lines between the key centers that the steps are laid out along, and a drag follows those lines' direction there; the lines are not drawn. Showing the widget without a spine and its placement are VectorCraft's own rules. Evidence: `blendwidget::tests::{a_blend_without_a_spine_shows_the_appearance_widget_alone, dragging_the_appearance_widget_of_a_blend_without_a_spine}`, `tests::blendopts::dragging_the_appearance_widget_of_a_blend_without_a_spine_is_one_undo_step`, `blend::tests::a_blend_without_a_spine_has_a_layout_line_through_its_key_centers`.
 
 - **Blend, mesh and envelope numbers given as text:** `object.blend.make` and `object.blend.options` (`steps`, `distance`, `value`), `object.envelope.makeWithWarp`, `resetWithWarp` and `options` (`bend`, `h`, `v`, `horizontalDistortion`, `verticalDistortion`), `object.envelope.makeWithMesh` and `resetWithMesh` (`rows`, `cols`, `columns`), `object.envelope.options` (`fidelity`), `object.mesh.create` (`rows`, `cols`, `columns`, `highlight`) and `object.mesh.setPointColor` (`opacity`) refuse a value other than a number or null, such as `"8"`, and change nothing. `object.mesh.create` refuses an `at` that is not `[x, y]`.
 

docs/ui-parity.md

@@ -436,7 +436,7 @@ next unit in the order a right-click on a ruler lists them, from Feet back to Po
 | Canvas context menu | done | Layers rows, panels and type have none (gap) |
 | SVG Interactivity panel: JavaScript for each object's events and the document's linked JavaScript files, written to SVG and read back as text | done | `svgInteractivity.*`, `ui.javascriptFilesDialog` |
 | Retype, Comments, Version History panels | missing | the last two are cloud features (out of scope) |
-| Blend panel (30.7) | partial | Window › Blend provides Type (Ease In, Ease Out, Ease In Out, Ease Out In), Ramp 0–100% and independent color Shift, alongside the existing blend controls. Easing is disabled without a spine. Original polynomial distributions approximate the publicly documented behavior; on-canvas easing handles remain missing. [Public source](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html) |
+| Blend panel (30.7) | partial | Window › Blend provides Type (Ease In, Ease Out, Ease In Out, Ease Out In), Ramp 0–100% and independent color Shift, alongside the existing blend controls. Easing is disabled without a spine. Original polynomial distributions approximate the publicly documented behavior. On-canvas Appearance and Easing widgets set Shift and Ramp; a blend without a spine shows the Appearance widget alone. [Public source](https://helpx.adobe.com/illustrator/desktop/manage-colors/apply-transparency-and-blending/blend-panel-overview.html) |
 | Gradient panel: Dither (30.0) | done | Dither box under the stops (`paint.editGradient` `dither`); dimmed behind the Stroke proxy, fills only; `panels::gradient` test |
 | Gradient panel: Method, Classic or Perceptual (30.0) | done | Method menu under the Stroke buttons for linear and radial gradients (`paint.editGradient` `method`); [public source](https://helpx.adobe.com/illustrator/desktop/paint-and-fill/create-and-edit-gradients/control-perceptual-interpolation-in-gradients.html); `panels::gradient` test |
 | Gradient panel: Presets (30.0) | done | Presets menu by library (theme) plus Saved: applies a preset to the gradient behind the active proxy, keeping its placement, one undo step; panel menu Save Gradient Preset…, Delete Gradient Preset, Hide/Show Presets (`gradient.presets.*`); `panels::gradient` tests |