Redline Annotation

Redline Annotation

Redlines eliminate guesswork. Annotate for the engineer who has never seen the design and cannot ask a question mid-sprint. The costly failure is the half-annotated file: the engineer eyeballs the missing values, QA files a stack of 2px-off tickets, and the fix cycle costs more than annotating properly would have.

Operating procedure

Step 1: Gather inputs

• Does a token system exist? If yes, annotate token names, not raw values.
• Is there a spacing grid convention (4px or 8px)? If yes, annotate exceptions to the grid, not the grid itself.
• Which frames and components are in scope, and does the engineer have inspect access to the design file and design system? Access changes how much must be written down.

Step 2: Establish the notation convention

Fix a compact notation before annotating and include it as a legend in the file. Consistency is what makes redlines scannable; ad-hoc phrasing forces engineers to re-parse every note.

Step 3: Annotate the always-list

• Spacing: all padding, margin, and gap values in pixels - or the token name if a token system exists. Internal padding as "p: 12 16" (top/bottom left/right), all four values if asymmetric. Draw a gap arrow between siblings and label the value.
• Sizing: width, height, and min/max constraints for every non-trivially-sized element. For auto widths, state "grows to fill container" vs. "shrinks to content".
• Type: font family, weight, size, line-height, letter-spacing, and color for every text style not covered by a named style.
• Color: token name first; raw hex only if no token exists. Include opacity when not 100%.
• Corner radius: per-corner values when they differ (top-left: 8, top-right: 8, bottom: 0).
• Z-order relationships for overlapping elements ("dropdown sits above modal overlay").

Never annotate only half of a symmetrical component - annotate fully so there is no ambiguity.

Step 4: Annotate behavior

Anything a developer cannot infer from a static frame:

• Hover, focus, active, and disabled states as deltas from default ("background shifts from surface-primary to surface-hover, 150ms ease-out"). Complex motion routes to motion-spec.
• Overflow: scroll direction, hidden vs. clipped vs. visible.
• Conditional visibility: what triggers show/hide, and whether the element is display:none or removed from the DOM.
• Truncation: max lines before ellipsis, tooltip on truncate yes/no.

Step 5: Skip what is already specified

• Values defined in a shared style or component the engineer can inspect - do not re-document every token.
• Structural markup and class names - annotate intent, not implementation; implementation is the engineer's domain.
• Every pixel that conforms to the stated grid convention - the grid is the rule, redlines mark the exceptions.

Step 6: Final delivery pass

Run the quality bar below before handing off.

Worked example

REDLINE CONVENTION + EXAMPLE - "Project card" component

Legend
  p: 12 16          padding, top/bottom left/right (4 values if asymmetric)
  g: 8              gap between siblings (arrow points between them)
  r: 8 8 0 0        corner radius per corner when unequal
  ->fill / ->hug    grows to fill container / shrinks to content
  [token]           token name; raw hex only when no token exists

Card container
  w: ->fill, max 400    h: ->hug, min 96
  p: 16                 r: 12
  bg: [surface-default] border: 1px [border-subtle]
  shadow: [elevation-1]

Title row
  g: 8 between avatar and title
  Avatar: 32x32, r: full
  Title: [text-primary], Inter 600 16/1.4, truncate 1 line, tooltip on truncate

States (deltas from default)
  hover:    bg [surface-default] -> [surface-hover], 150ms ease-out
  focus:    2px [focus-ring] outline, 2px offset
  disabled: opacity 0.4, no pointer events

Z-order: card menu sits above sibling cards, below modal overlay.
Grid: 4px convention; only exception here is avatar-to-edge 14px (optical).

Deliverable

Produce an annotated file or spec sheet containing: the notation legend, complete measurements for every in-scope element (spacing, sizing, type, color, radius, z-order), behavior notes for every state and conditional, an explicit list of grid exceptions, and the owner's name with a last-updated date on the file itself.

Do NOT

• Do not annotate half a component and let symmetry be assumed - assumed symmetry is where 2px bugs live.
• Do not write raw hex when a token exists; raw values silently fork the design system.
• Do not re-document the entire token library; engineers with system access need exceptions, not an echo.
• Do not annotate class names or markup structure - prescribing implementation creates friction and goes stale.
• Do not leave states unannotated because "hover is obvious" - the exact target color and duration are never obvious.

Quality bar

• All annotations are visible without clicking into layers.
• A legend is included whenever custom notation is used.
• The file carries a last-updated date and the design owner's name.
• Every interactive element has all four states (hover, focus, active, disabled) specified or explicitly marked not applicable.
• Responsive behavior is called out inline or linked to the responsive-spec.
• An engineer with no file access could build the component from the annotations alone.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: SkillMedev
• Source: SkillMedev/designer-to-dev-handoff
• License: MIT
• Homepage: https://skillme.dev/pack/designer-to-dev-handoff

Install and usage instructions live in the source repository linked above.