Instances are essentially state machines. When you run a process, genroc validates the input data and stores the initial state.

The instance is then picked up by the engine, which advances it into a new state.

Listing instances

To list current instances on the server, use the instances command.

> genctl instances
ID        STATUS     PROCESS   UPDATED  CREATED  CODE  ERROR
006y1m7d  completed  hello@v1  22h ago  22h ago
3kjfx4vm  completed  hello@v1  just now just now

You can also filter by various parameters like --status or --process (process name); check the full cli docs for details.

Info about the instance

To check the current state of an instance, use the get command.

> genctl get @last
ID:       006y1m7d
Process:  hello@v1
Status:   completed
Task:     greet
Created:  2026-09-30 12:53:58  (just now)
Updated:  2026-09-30 12:53:58  (just now)

Output:
at: "2026-09-30T10:53:58.669Z"
greeting: hello, world

The example shows a completed instance, as indicated by status.

The output can also contain Phase, Error, Code and Error data. These are listed only if they have a value.

Task

The task field tells you which task is being or is going to be performed. If the instance has finished, it tells you which task was the last.

Phase

Some tasks are not atomic (external/children), meaning the engine needs to perform multiple "ticks" per task.

In that case the phase field is used to distinguish between the sub-states. It is shown only when it's not empty, and has the following meaning:

Phase	Meaning
children	Child instances were spawned; the parent is blocked until all of them finish.
collecting	All children have finished; the engine still has to merge their outputs into the parent.
external	Parked on an external task, waiting for an answer or for its timeout.

Error, Code and Error data

Describes an error if the status is raised or failed. System error codes contain a dot (e.g. result.invalid); user-defined codes can't contain one.

Error data is an optional payload of panic or raise.

Check the task error reference.

Output

This is the public output of the process. It's available once the instance has completed, if the process defines output.

Instance lifecycle

Genroc instances communicate their lifecycle through the status field.

Settled marks a terminal state: no work moves and nothing advances out of it. Accepts a result is whether a worker's answer to an external task is still delivered — a pause suspends execution, not delivery.

Status	Settled	Accepts a result	Means
running	no	yes	advancing, or waiting on a timer, a child or an external task
pausing	no	yes	a pause was requested while a task was in flight; it settles at the next task boundary
paused	no	yes	not being advanced, and able to resume exactly where it stopped; timers keep running
failing	no	no	doomed by an error, and draining the descendants still in flight
cancelling	no	no	a cancel was requested while a task was in flight; it settles at the next task boundary
completed	yes	no	finished by reaching the end of its definition
failed	yes	no	stopped by an error; retryable, which is what separates it from the other settled outcomes
raised	yes	no	concluded by a raise clause — a condition, not a defect, and catchable by the parent
cancelled	yes	no	stopped for good by an operator — terminal, and unlike a pause there is no way back

You have four commands at your disposal: pause, resume, cancel and retry. They can only be applied to root instances, and they apply to the whole tree. They are refused on children.

Pause (and resume)

genctl pause @last

This will pause the instance if it's running. The instance can then be resumed by the resume command with the same syntax.

pause returns at once. An instance a worker is executing goes to pausing and becomes paused when that task finishes, so no worker is forcefully interrupted and no work is repeated.

Pause/resume operates strictly within the definition boundaries (they never add a retry), so you can use them as you like without changing the instance's behavior. The only caveat is that timers keep running even when the instance is paused, so a timeout (e.g. on an external task) can run out while the instance is paused.

An external worker can still deliver a result through resolve, even if the instance has switched to the paused status.

Cancel

genctl cancel @last

This cancels the instance for good — a cancelled instance can't be resumed.

Cancel also goes through cancelling while the workers settle.

An external worker can't deliver a result through resolve (it will fail) if the instance was cancelled while the worker was running.

Retry

genctl retry @last

Retries a failed instance; it basically adds one extra attempt on the current task (it doesn't reset the retry counter, so it tries once and goes straight back to failed on an error).

Retry can't be used on paused, cancelled or raised statuses.

If the task is only_once, retry needs the --force flag, because a retry could easily break the only_once rule by accident.

Instance logs

To see a detailed history of an instance, use the logs command.

> genctl logs 006y1m7d
TIME      LEVEL  ID        EVENT             TASK
--- 2026-09-30 +02:00 ---
12:53:58  INFO   006y1m7d  inst_created                      by=no-auth:anonymous input={"who":"world"}
12:53:58  INFO   006y1m7d  child_spawned     greet           msg="1 children"
12:53:58  INFO   3k1nz7pq  inst_created                      input={"code":"async function greet (input) {\n    return …
12:53:58  INFO   3k1nz7pq  extern_armed      eval_node       msg="token=3k1nz7pq.0 timeout=30s -> 2026-09-30T10:54:28Z"
12:53:58  INFO   3k1nz7pq  extern_resolved   eval_node
12:53:58  INFO   3k1nz7pq  inst_completed    eval_node       output={"at":"2026-09-30T10:53:58.669Z","greeting":"hello,…
12:53:58  INFO   006y1m7d  child_collected   greet
12:53:58  INFO   006y1m7d  inst_completed    greet           output={"at":"2026-09-30T10:53:58.669Z","greeting":"hello,…

When you target a root, the logs include its children's logs as well.

Instance detail

If you want more info about an instance, use the detail command.

It prints everything get does, plus extra info about the internal state.

> genctl detail @last
ID:       006y1m7d
Process:  hello@v1
Status:   completed
Task:     greet
Created:  2026-09-30 12:53:58  (just now)
Updated:  2026-09-30 12:53:58  (just now)
Epochs:   lease 2, task 0, parent task 0, external claim 0

Output:
at: "2026-09-30T10:53:58.669Z"
greeting: hello, world

Children:
greet: 3k1nz7pq

State:
input:
  who: world
last_error: null
outputs:
  greet:
    at: "2026-09-30T10:53:58.669Z"
    greeting: hello, world

Field	Meaning
Parent	The parent instance and the task that spawned it. Children only.
Call stack	Every ancestor instance, root first. Children only.
Wake at	When a pending timer fires - a delay, a retry backoff or a timeout.
Lease	The engine worker advancing the instance and how long it has left, or that the lease expired.
External	While parked on an external task: unclaimed, claimed by …, or that the claim expired.
Epochs	Counters that keep a stale worker or an old answer from overwriting newer work. For debugging.
Children	The spawned instances, keyed by the task that spawned them.
State	input, each task's output under outputs, and last_error - the error last caught by on_error.

Only Epochs is always shown; the rest appear when they have a value.