Fix or iterate on existing art

Editing someone's work has a failure mode that drawing from scratch does not: breaking something that was already correct. The whole procedure is built around not doing that.

preflight
sprite_info
look op="preview"

For a targeted edit, also look op="ascii" on the region. You cannot edit pixels precisely from a description.

Never assume layer names, frame counts or the palette. Drawing into the wrong layer is the most common way an agent damages someone's file. When two groups hold same-named layers (left/arm, right/arm), a bare name is refused — pass the group path rather than renaming the user's layers.

For anything beyond a small touch-up, state the plan in one line and let the user stop you. Especially before: changing the palette, resizing the canvas, merging layers, or editing a layer you did not create.

• A selection limits draw, recolor and transform to one area.
• A layer target keeps you out of everything else.
• A region on recolor avoids touching the whole cel.

Scoping is cheaper than repairing.

One draw with all its ops, one recolor. That is one Ctrl+Z for the user if they dislike it. Use label to describe the intent — it becomes their undo entry.

For a pixel-level fix, edit the text, not coordinates: look op="ascii" layer=… rulers=false region=… gives bare rows, the legend and origin; change the wrong cells and send the same rows back as one draw kind grid at that origin. Only that rectangle is touched, and its transparent cells erase — pass transparent:"skip" when you mean to add pixels without clearing any. Glyphs are palette indices, so pieces read separately share one legend: merge their legends when rows from one piece land in another. Only glyphs listed in offPalette (colours outside the palette) can change between reads.

look op="diff" fromFrame=… toFrame=…

for animation work, or look op="ascii" on the region for a static edit. A preview shows you the result; a diff shows you the change, including the parts you did not intend. The diff's changedBounds is the quick test: if you edited the hand and the box spans the whole sprite, something else moved.

validate

Report what changed and what you deliberately left alone.

Request	Usually means
"more contrast"	Widen the value range of the ramps, not the hue
"cleaner"	Remove strays, even out line runs, merge near-duplicate colours
"more detail"	Usually wrong at small sizes — ask what should read better
"pop more"	Contrast against the background, or a brighter accent
"less flat"	Shading exists but does not hue-shift, or has no light direction
"muddy colours"	Too many near-duplicates — palette op="extract" on a copy, or analyze + snap
"add a label / score / title"	draw kind text; measure with measureOnly first so it lands centred
"closer to the reference / concept"	look op="compare", list the three to five largest mismatches, fix only those
"off / uncanny"	Run aseprite:review; name the specific cause

Reflect your reading back before acting on it. "More detail" on a 16×16 sprite usually means the sprite needs to be bigger, and that is worth one question.

• Do not redraw a sprite from scratch because it is easier than editing it, unless the user asked for that.
• Do not "improve" things nobody mentioned.
• Do not widen the palette to fit a colour you chose. Say the palette lacks it.
• Do not flatten, resize or re-index without being asked.

aseprite:review, rules://00-core-principles, rules://92-generated-art-tells for what makes art read as machine-made, and the subject file for the part you are fixing (skill://studio, Subject rules) — "fix the hands" starts at rules://34-hands-and-feet.