Logic handler input, output and subscriptions

A north-facing handler has INPUT / NETWORK / OUTPUT left to right. Wire computer NETWORK to handler NETWORK for discovery, factory readout to INPUT, controlled machines to OUTPUT. No internal role feedthrough exists. External feedback is possible only if you wire it deliberately. Obtain local io = peripheral.find("logic_handler", "red"). Discovery red is independent of INPUT selection red/green/both.

Complete methods

Signature	Exact returns
io.readSignal(input, signal)	Int32, absent gives 0
io.readSignals(input)	Defensive canonical nonzero Signal array
io.getInputStatus()	{red_connected=boolean, green_connected=boolean} from actual INPUT edges
io.getOutput()	Defensive Signal array of this handler's configured contribution only
io.setOutput(signals)	None; complete bank replacement and writer transfer
io.clearOutput()	None; equivalent to setOutput({})
io.subscribe(options, handler_name)	Run-scoped subscription string
io.unsubscribe(subscription_id)	Boolean; remove own binding's registration and queued samples; false when absent
io.getLimits()	Defensive shared + device ceilings

Strict dot calls; extra arguments/unknown options fail. input is exactly red, green or both. A SignalId is {type="item"/"fluid"/"virtual", name=prototype, quality=quality_name?}; a Signal is {signal=SignalId,count=Int32}. Type/name and quality must exist. Quality defaults normal and is explicit on readback. No wildcards or count coercion. Complete identities sort by type/name/quality.

Both-input sums wrap signed32 per identity using ((red+green+2147483648)%4294967296)-2147483648, without physically connecting colors. Negative counts are legal. Duplicate normalized output identities, including duplicate zeros, are refused before mutation; zero entries are omitted. Failed validation/admission preserves bank and writer.

Output is one bank mirrored to red and green; native external contributors can make network totals different. getOutput does not read those totals. A successful write/clear transfers the entire bank's ownership to this computer/run/discovery color. Another writer's subsequent success replaces that ownership.

Subscriptions

options={input=InputSelection, signals={SignalId,...}?, initial=boolean?}. Input is required; omitted signals means all, otherwise nonempty unique filters; initial defaults false. Handler name must be declared. Registrations persist by name/data, never saved functions, and bind the selected discovery color. Losing red cannot silently rebind green. IDs from another run/binding are invalid.

One actual-tick sample per powered subscribed handler. Initial=false baselines current input without an event; true queues next sampling tick with empty previous and false previous connectivity. Notify only changed selected values or connectivity. A vanished nonzero signal has current=0 in changes. An empty network connecting/disconnecting may produce empty changes with changed connectivity. Within-tick transients are not observed.

signal_changed extends BaseEvent with:

Field	Type / meaning
subscription_id	string
peripheral, wire	string name and selected discovery Wire
input	red / green / both
sample_tick	Tick of observation, not callback dispatch
initial, resync	booleans
previous, current	canonical Signal arrays
changes	array of {signal=SignalId, previous=Int32, current=Int32}
previous_connected, connected	maps with selected red/green boolean keys only

Queue admission, not callback dispatch, advances the baseline. Computer/handler outages discard obsolete queued samples but retain registration/baseline. Restoration resyncs current values, not every missed transition; previous can describe an admitted sample whose callback was discarded. Native circuits report prior circuit update state; no immediate recursive effect or zero-latency propagation is promised.

Fail-safe ownership and persistence

Stop, fault, power loss, removal, authority change or loss of the owner's selected path clears only that run's still-owned bank. A stopping old writer cannot clear a later writer's bank. Source failure cannot suppress cleanup. On restoration output remains empty until another successful write. Cold load retains a valid bank/owner/subscriptions without replaying start or republishing writes. New placement/clones start zero/unowned.

State/KV/display and applied factory configuration are not rolled back by output cleanup. Use native conditions that stop on absent output for fail-safe control. Unexpected native bank failure restores prior contribution or retains explicit recovery and clears output; never assume a callback-wide factory transaction.

Bounds and use

Initial caps: 64 signal slots per input/combined snapshot/output; 64 filter signals; 64 subscriptions per computer shared with general registrations; 128 sampled handlers; 1,024 aggregate subscriptions; 128 owned banks. Sample interval 1 tick, fail-safe target 1 tick, notification/topology ceiling 60 ticks is provisional. The native prototype×quality read envelope is pre-admitted; large modded universes can refuse instead of doing unbounded work. Queue overflow or sampling/notification maintenance refusal visibly faults affected runs, not silently loses history.

Use logic-controller and the first inserter tutorial. If reads stay zero, check chest read mode and INPUT color, distinguish disconnected getInputStatus from connected zero, and use exact quality. If output vanishes, inspect owner path/power/fault, not just native downstream condition. Shared errors apply.