Concepts

Nacre is mother-of-pearl, the lining an oyster grows on the inside of its shell. This package is that lining for App hosts: the shell client that windows, commands, keys and the App directory are built from. Oyster’s page uses it, and any shell can import it without the Oyster server.

Core concepts

@fungi.computer/nacre supplies the client side of hosting Apps. It can be imported independently of the Workers server and Node packing helpers. The same exports are available through focused entries:

Entry	Contract
./workbench	Workbench host contract, shared child-window host, Gill layout and arranger shapes.
./command-host	A Whistle graph that admits mounted commands against verified Release declarations.
./keys	DOM key dispatch and shared chord matching.
./commands	Window, App picker and command palette declarations over host callbacks.
./window-manager	Window generations, visibility, navigation, cancellation and disposal.
./app-directory	App addresses, reusable directory rows and catalog metadata.

./shell-module is the contract between a host and the shell it runs, and is imported on its own rather than through the root entry. A shell Release exports mountShell(root, input) (MountShell); input (ShellMountInput) carries the workbench handle, the shell installation’s AppStorage and methods.call(method, input) for its declared backend methods, which takes the input as JSON text and resolves with the decoded JSON result. importShellModule(moduleUrl, hostOrigin) imports the picked shell’s module from the host’s own origin, checks that it exports mountShell, and rejects with ShellModuleError otherwise. The host never bundles a shell.

Supply your own mount adapter to createWindowManager. It receives the container, launch descriptor, cancellation signal and navigation callbacks; its returned handle owns visibility, reconfiguration and disposal. The manager disposes stale mounts and serializes changes to each window. It neither picks Apps nor grants capabilities.

createAppSurfaceCommandHost owns command contribution and focus. Give mount(id, declarations) the verified Release’s declarations and pass the returned handlers to Agar’s connectAppHost. A mounted App cannot introduce an undeclared command or claim the reserved shell chord. Dispose its command mount when its iframe closes, and dispose the command host with the shell. installShellKeys attaches DOM listeners only when called; its return value removes them. Terminal shells can use the command and window owners without a DOM.

Directory metadata is not launch authority. A host extends the public row schema with its own permission model and admits each mount itself. Fungi’s Team directory, Team settings capability and signed Hub/host protocol live in its private consumers; the public shell imports none of them.