Cameras and microphones

mediaDevices({ name, create? }) scans the device list on placement and re-scans on Scan, on DevicesChanged (wired to devicechange), and on every placement, answering Refreshed { devices } with { deviceId, groupId, kind, label }. Denial lands as denied while keeping the last list; another failure keeps the last list and notes the error; an unknown kind fails the scan at the boundary instead of entering the Model.

mediaStream({ name, request? }) holds one live stream in a Managed Resource while the Model asks for it (requesting or live). Started requests with the placed { audio, video } constraints; Stopped and Ended release it, which stops every track. Denial parks at denied, any other failure at idle with the error; both clear the requirement, so a failing device never spins an acquire loop, and Started retries. The LiveStream tag and service are exported for a Command that attaches the stream to a video element. One assembly holds one stream.

permissions({ name, create? }) queries args.names on acquire and watches each status object's onchange through an ordered queue. Snapshot replaces the states map, Changed merges one, Cleared empties on release, which also detaches every handler. An unknown name or state string fails the acquire; it never becomes a Model fact. Unlike mediaStream, it keeps its requirement after a failure, so the two retry differently.

The factories take create or request doubles so a test substitutes the platform instead of stubbing globals.

Fullscreen#

enterFullscreen(element) and exitFullscreen() are Commands yielding Entered or Exited, or Failed for a rejected request or a missing capability, with a legacy webkit fallback. fullscreenChanges() is an entry that starts with the current answer, then follows flips as Changed { active }. There is no Model: the document owns fullscreen state.

Failure#

Without the API (a server, an old browser) an entry is empty, a scan fails as a Message, and an acquisition error becomes its failure Message. Nothing throws.