Deploy processes and run instances

These are the everyday operations against the v2 REST API (all also available over the Falcon protocol).

• Deploy a model — POST /v2/deployments with the BPMN 2.0 XML. Deployment is idempotent: a byte-for-byte-identical redeploy reuses the current version; a changed model becomes the next version.
• Start an instance — POST /v2/process-instances by processDefinitionId or processDefinitionKey. Variables on the request seed the instance. With awaitCompletion: true the call blocks (up to requestTimeout, default 5 s) and returns the final variables when processCompleted is true. Note: on timeout Nano returns 200 with processCompleted: false and the processInstanceKey (so you can poll), rather than Camunda's 504.
• Work jobs — POST /v2/jobs/activation activates jobs of a type (with Camunda-style long-polling), …/completion completes a job and merges its output into the instance (driving downstream routing), …/failure sets remaining retries, and …/error raises a BPMN business error (routing to a matching error boundary event if there is one).
• Recover from incidents — when a job runs out of retries (or a condition or uncaught error fails), an incident is raised and the work parks. The recovery loop is: give the job retries again with PATCH /v2/jobs/{key} (or correct the data behind a gateway incident via PUT /v2/element-instances/{key}/variables), then POST /v2/incidents/{incidentKey}/resolution, which retries the failed work rather than just clearing the record.
• Correlate messages — POST /v2/messages/publication and …/correlation deliver a message to any matching open subscription, releasing a catch event, interrupting an activity via a boundary event, or creating a new instance for a message start event. Messages are not buffered: with no match, the message is dropped.
• Observe state — the search/get endpoints for process instances, jobs, incidents, and variables expose engine state. They support the full v2 query contract: operator filters ($eq, $neq, $in, $notIn, $exists, $like with */? wildcards), multi-field sort, and all four pagination shapes (limit, offset, forward cursor, backward cursor).

Reads are eventually consistent. A search/get issued in the instant after a write may briefly not observe it (typically sub-millisecond), exactly like Camunda 8's Operate read channel. The read side is a durable projection, so queries are served from it, not from live engine memory.