Adapting Tessera

Keep Tessera's policy, configuration, workspace rules, keymap, layout choices and desktop behavior in its own Sigil modules. The integration can be developed on a separate branch while its current compositor remains usable.

Tessera responsibility	sigil-wm interface
Native bridge and owner lifetime	`(sigil wm host)` and copied native ABI
Window/output/workspace bookkeeping	`(sigil wm model)` snapshots and explicit tree operations
Layout result	`(sigil wm layout)` arranger and `(sigil wm scene)` complete plan
Floating restoration and fullscreen selection	Tessera state and explicit client boxes/visibility/protocol states
Binding lookup and semantic commands	`(sigil wm input)` key/button hooks
Interactive geometry and hover focus	Opt-in motion hook, then explicit geometry/focus commands
Title font, shaping and images	Optional `(sigil wm draw)`; retain Tessera's presentation choices
Compositor-owned drawings	Copied pixel descriptor, logical rectangle and scale
Live commands and inspection	`(sigil wm repl)` expression IPC

Treat native object IDs as handles within one host lifetime. Distinguish desired layout from configure acknowledgement and committed client size. Update policy only from copied events and transaction completions; never depend on native pointers or integer opcodes from the previous bridge.