Slot Grid

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12x4 live grid overlay for composition triggering, per-composition slot-playback trim settings, and multi-layer background playback.

Overview

The Slot Grid sits on top of the Timeline panel and turns compositions into launchable slots.

4 rows map to playback layers A through D
12 columns provide launch positions per layer
grid/timeline transitions are animated through slotGridProgress
each active layer keeps its own wall-clock playback state

Opening The Grid

You can switch between the timeline and Slot Grid through:

the dedicated toolbar toggle button
Ctrl+Shift+Scroll / Cmd+Shift+Scroll

Zooming back into the timeline from the grid is only allowed while hovering a filled slot.

Slot Interaction

Default Click Flow

On the current default path, clicking a filled slot:

ensures slot-clip settings exist for that composition
selects the slot composition
opens the Properties panel to the Slot Clip tab
opens the composition in the editor and activates it on the corresponding live layer

Live Trigger Flag

When window.__ENGINE_FLAGS__.useLiveSlotTrigger is enabled, the primary click path changes:

clicking a slot triggers the live layer directly without forcing the editor switch first
column-header clicks use the same live-trigger path for the whole column

Other Actions

re-clicking an active slot restarts playback from the slot trimIn point
clicking an empty slot clears that layer
dragging moves or swaps slot assignments
clicking a column header activates every filled slot in that column
dragging media from the Media panel onto a slot creates and assigns a composition for that media
each row has an opacity slider for its live layer; filled slots show a miniature timeline and live time overlay
right-clicking a filled slot opens Open in Editor, Map MIDI to Slot, and Remove from Slot
Map MIDI to Slot opens the MIDI Mapping panel and arms a pending MIDI-learn target for that slot; a binding is saved after MIDI input is learned

Slot Clip Settings

Each slotted composition has its own slot-playback trim state:

trimIn
trimOut
endBehavior

The current defaults are:

trimIn = 0
trimOut = composition duration
endBehavior = loop

These settings are stored in mediaStore.slotClipSettings, persisted with the project, and edited through the Slot Clip properties tab.

Slot launches use the configured slot window, not the composition editor playhead. The Slot Clip tab renders the composition tracks, the active trim window, and the current layer playhead in the same timeline surface so the tab reflects the playback state used by layerPlaybackManager.

Multi-Layer Playback

Each active slot layer runs independently from the global editor timeline.

background layers keep their own anchor time
active layers can keep running even when the editor focus changes
background video elements are muted by default
deactivating a layer removes its active assignment and cleans up its background media

The background playback plumbing is managed by layerPlaybackManager.

Warm Decks

Warm decks are implemented but disabled by default. When window.__ENGINE_FLAGS__.useWarmSlotDecks is enabled, the grid can prepare reusable slot-owned playback decks before activation.

Deck badges use these states:

Badge	Meaning
`C`	cold
`Wi`	warming
`Wa`	warm
`H`	hot
`F`	failed
`D`	disposed

Warm decks let a prepared slot be adopted onto a live layer with less activation work at trigger time.