Blog / 6 min read · 2026-05-24

The "Keep X identical" lock — discipline for multi-turn Gemini Omni editing

Gemini Omni's conversational editing chain breaks unless you list what to preserve in every follow-up turn. The "Keep X identical" pattern, why it matters, and how to use it cleanly across turns.

Gemini Omni’s headline feature is conversational editing — refine a video over multiple turns instead of regenerating from scratch. But community testing keeps surfacing the same failure pattern: by turn three the entire scene has drifted. The character’s outfit changed. The lighting flipped from warm to cool. The camera angle silently rotated 30 degrees.

The fix is one short discipline that DeepMind’s prompt guide buries and most tutorials skip past: explicitly list what to preserve in every follow-up turn.

The pattern

[Change instruction]. Keep [X, Y, Z] exactly the same.

That’s it. Every follow-up turn after the initial generation should end with a “keep [list] identical” clause. Without it, Omni treats each turn as license to restyle the whole scene around your change.

A worked example

Turn 1 (initial generation):

A woman in a red coat walks through a snowy Tokyo alley at night. Camera tracks beside her, slow handheld, 16:9, 8 seconds, one continuous shot.

Turn 2, no lock (typical mistake):

Make the coat blue.

What Omni does: changes the coat to blue and swaps the alley for a generic street, adjusts the lighting from cool blue night to warm orange, and replaces the woman’s face. You wanted a one-variable change; you got a full rerender.

Turn 2, with lock (correct):

Make the coat blue. Keep the woman’s face, the snowy Tokyo alley, the night lighting, the slow handheld tracking camera, and the 8-second duration exactly the same.

What Omni does: one variable changes. Everything else holds.

Why Omni needs the lock

The model can’t tell which scene elements you want to preserve and which are incidental. When you say “make the coat blue,” the entire prior frame is just input — the model treats it as a starting point for re-imagining, not a fixed scene.

Listing the preserved elements raises their weight in the regeneration. Omni is then incentivised to find the smallest delta that satisfies your change instruction without breaking the locks.

Atlas Cloud’s hands-on multi-turn review documented this directly: prompts with explicit locks scored 4.2/5 on cross-turn consistency. Prompts without locks scored 2.1/5.

What to lock

Lock everything you didn’t explicitly ask to change. Common categories:

• Character identity — face, hair, build, ethnicity, age range
• Wardrobe — anything you’re not changing in this turn
• Environment — location, time of day, weather, season
• Lighting — color temperature, direction, intensity
• Camera — angle, movement, framing, aspect ratio
• Duration — same number of seconds

Be specific. “Keep the lighting the same” is weaker than “keep the warm tungsten lighting from the left.” The more concrete the lock, the more reliably Omni respects it.

When the lock isn’t enough

Two cases where even good locks don’t save you:

1. Shot 5+ in a chain. Past four turns, Omni’s character consistency drops to about 3/5 regardless of locks. Plan productions in chunks of three to four shots; regenerate the anchor from scratch when starting a new chunk.

2. Cross-category changes. Asking Omni to change both lighting and environment in one turn confuses the lock — split into two separate turns. One variable per turn is the rule of thumb.

Locking + the trigger pattern

The lock combines well with Omni’s other unique pattern: the trigger (“When [action], [transformation]”). Example from DeepMind’s official mirror-ripple demo:

A woman reaches toward a mirror. When her fingertips touch the glass, make the mirror ripple like liquid and her arm turn to reflective mirror material. Keep the parlor, her face, and the warm lighting identical.

Both patterns in one turn: trigger for the transformation, lock for everything else. This is what makes Omni’s conversational editing actually usable for production work instead of just demos.

Quick checklist

Before sending any follow-up turn, ask:

• Have I named exactly one variable to change?
• Have I listed every other scene element that should stay?
• Are my locks specific (color, direction, intensity) not vague (“the lighting”)?
• Am I past shot 4? If so, plan a regeneration.

Skip the locks and you’re back to text-to-video without iteration. Use them and conversational editing becomes the production tool Google demoed at I/O.

Related

• Full Gemini Omni prompt guide — base formula, camera vocab, opening-line trick
• Trigger pattern for VFX — Omni’s “When [action], [transformation]” syntax
• Camera vocabulary Omni parses — the verbs to use in your locks
• Glossary — definitions for keep-x-identical-lock and related terms