Illustration Rules

Edit vs Regenerate — The Asymmetry Rule

• Content ADDITIONS (adding a person, changing composition) → always REGENERATE from the full prompt. Editing strips the style when adding new visual elements.
• Content MODIFICATIONS (changing a hat, making text bigger) → REGENERATE. Same style-stripping problem as additions.
• Content REMOVAL (erase a label, remove a border) → EDIT works well. The model preserves style when only removing content.

Rule of thumb: if the model must draw something new, regenerate. If it only erases existing content, edit.

Edit Prompt Safety — Three Mandatory Components

Every image edit prompt MUST include:

1. "DO NOT add any new elements." — suppresses Gemini's aggressive decoration
2. "Let background continue naturally — no parchment patch." — prevents flat-fill artifacts when erasing
3. Explicit preservation list: "Keep the [X]. Keep the [Y]." — prevents unintended removal of nearby elements

The --edit and --fix commands auto-append #1 and #2, but #3 must always be added manually.

Style-Anchor Discipline

Never simplify or rewrite the speaker's original style anchor when iterating. The specificity of the anchor (period vocabulary, document conventions, material constraints) is what produces a coherent style across slides; pruning it for "cleanliness" reverts the output to a generic illustrative default.

Append to the anchor for new constraints — don't replace.

Build Process — Progressive Reveals

Builds (slide-by-slide reveals where elements appear progressively) are the hardest illustration case because each step must visually match the others.

Chain backwards from the full image:

• Stage N (final) = full slide image
• Stage N-1 = full minus the last element to reveal
• ... → Stage 00 = empty frame (title + borders only, no content)

Each step's input is the PREVIOUS step's output (chained edits work because the per-step diff is small and the style is preserved on erasure — see the edit-vs-regenerate asymmetry rule above).

Don't:

• Use PIL or parchment masking to "blank out" regions — the texture mismatch is obvious. Always erase via image-edit, not pixel paste.
• Generate each build stage independently from prompts — visual drift between stages will be jarring even if each individual stage looks fine.

Naming convention: builds/slide-NN-build-MM.jpg where MM is the stage index (00 is empty, 01 adds the first element, etc.).

For checklists or progressive-state slides (e.g., a form filling in across multiple slides), use the same approach: take the most-complete version as the base and image-edit backwards to earlier states. Adding checkmarks via edit preserves visual consistency far better than regenerating from prompt.

Targeted Fixes Beat Regeneration

When an image is "almost perfect" — say, one mislabeled callout or a single extra element — do a targeted image-edit fix pass. Regenerating from scratch risks losing all the things that already work. The edit-only-removes asymmetry applies: erase the wrong element, then if needed regenerate just the corrected element.

Iteration Hygiene

Save experiment versions (v2, v3, v4) instead of overwriting the working file. Slide illustrations take many iterations to converge; stomping on a near-good output to try one more variation loses information that may have been worth keeping. The disk cost of saving all attempts is trivial compared to the cost of regenerating a known-good output you accidentally clobbered.