What the server holds. Threaded through the sequence without being copied: handle and tick get the only reference, so an Array or HashMap in it is updated in place (run with LEAN_ABORT_ON_NONLINEAR=1 and markLinear to check).

The world a sequence starts with, from the sequence's seed: random, so other accounts' likes and posts differ between sequences. A generator rather than a constant, so the world is built per sequence and never shared with a global.

Which requests go to the server. The rest (and every loadImage) are answered as without one, by Custom.replies or the default.

The server handles request id: the world after and its reply. Called each time the request reaches the server: once, or twice when the host delivers it twice (retransmit). A reply that doesn't answer the request's kind (Reply.answers) is replaced by a failure.

The world acting on its own between steps: other accounts liking, new posts, the AppView catching up.

What the app hears for a fault (failed before, or lost after): by default a timeout or a network failure.

Checks over the app's state and the world, after every step (the first frame included). Counted under the claim as server.

Checks once a sequence ends and the host has answered everything outstanding, every request reaching the server first (no faults): "once every reply is in, each post shows what the server holds". Counted under the claim as serverDrained.

The world in words, for a failure's message.

How often, relative to the 30 of handling a request and of delivering its reply, the host injects each fault and lets the world act (0: never).

How often the host delivers a request the server has handled to it again, before its reply is sent (a proxy's retry): the server handles it twice, and the app hears the second answer. Off by default: a refusal of the second delivery after the first was applied is a "refused" that did something, which no client can tell from the reply, so it only makes sense for a server that answers a repeated request as it did the first time.

Scripts of text operations for a field's edit move (by claim id), each operation sent as its own event; none keeps the default generator.

The smallest window the app supports in a state; none means the app's App.minSize, or the view's preferred size when that is 0 × 0.

Moves that have no control on purpose (keyboard-only), exempt from presence.

The frame-time budget for one step (update, view, layout), in nanoseconds.

Replies for the fuzzer's host to answer request id with, in the current state (docs/fuzz.md, "The host"): for structured answers, such as the JSON a parser expects. none keeps the default, which knows only the reply's shape (random bytes, a status, a size, a fault). A reply that doesn't answer the request's kind (Reply.answers) is replaced by a failure, since the host never sends one.

Events for the fuzzer's host to send an active subscription; none keeps the default.

Checks over one step, for claims stated about every step rather than every state (a reply to a request not waited for changes nothing; scores only improve). Counted under the claim as relation. A message the runtime drops (a reply to a cancelled or unknown id, an event from a stopped subscription) is also given straight to receive, so a claim about every message is checked on those too.

Checks once a sequence ends and the host has answered everything outstanding (with replies or the default): every load finished, nothing still waiting. Counted under the claim as drained.

Checks against what the runtime still owes the app, after every step (the first frame included): the state, and the ids of the requests the runtime holds for it, sent and not answered or queued behind its in-flight limit, and not cancelled (World.entries: sent oldest first, then queued). These are exactly the ids the app can still hear a reply under. Counted under the claim as outstanding.

How often, relative to the others, the fuzzer picks a control's action among those enabled on screen (default 1): weight a move reachable only deep in the app up, one that ends the state under test (Sign out) down, or a few keys up so presses race their own replies. A weight of 0 never picks the control; its presence is still checked.

A server with a world of its own, for claims stated against what it holds (docs/fuzz.md, "A server"). none answers every request with replies or the default.

Checks of the Dock badge, after every step: the state, and the label the host shows, the last badge effect's (none before any; ^1030). Counted under the claim as badge.