EMEP Experiment Lifecycle State Machine

State diagram for Experiment states, valid and invalid transitions, and operator actions permitted at each stage.

Every EMEP experiment follows a strict lifecycle. States track progress from creation through completion, failure, or archival. This page defines the state machine, valid transitions, and operator actions.

State Diagram

State Definitions

State	Definition	Entry Condition
CREATED	Experiment defined with configuration and benchmark splits	Operator submits experiment configuration
PREPARING	Resources allocated, models imported, environment validated	System confirms resource availability and model integrity
RUNNING	Merge operations or evolutionary search actively executing	Environment validation passes
EVALUATING	Candidate models undergoing benchmark evaluation	Merge or evolution stage completes
COMPLETED	All operations finished, results recorded, artifacts stored	All benchmarks complete without error
FAILED	Unrecoverable error terminated the experiment	Runtime or evaluation error that cannot be retried
CANCELLED	Operator or policy halted the experiment before completion	Explicit abort command issued
ARCHIVED	Experiment retained for audit but no longer active	Operator archives a COMPLETED, FAILED, or CANCELLED experiment

Valid Transitions

From	To	Trigger
CREATED	PREPARING	System allocates resources and begins model import
PREPARING	RUNNING	All imports and validations succeed
PREPARING	FAILED	Import failure, shape mismatch, or environment error
PREPARING	CANCELLED	Operator issues abort before RUNNING
RUNNING	EVALUATING	Merge or evolution stage signals completion
RUNNING	FAILED	OOM, numerical error, or unhandled exception
RUNNING	CANCELLED	Operator issues abort during execution
EVALUATING	COMPLETED	All benchmarks finish, metrics logged, artifacts signed
EVALUATING	FAILED	Benchmark corruption, timeout, or contamination detected
EVALUATING	CANCELLED	Operator issues abort during evaluation
COMPLETED	ARCHIVED	Operator requests archival after review
FAILED	ARCHIVED	Operator requests archival for post-mortem
CANCELLED	ARCHIVED	Operator requests archival for record keeping

Invalid Transitions

The following transitions are explicitly prohibited:

Invalid Transition	Reason
CREATED → RUNNING	Skipping preparation risks environment mismatch
CREATED → EVALUATING	No candidates exist without preparation and execution
CREATED → COMPLETED	Impossible without execution
RUNNING → COMPLETED	Evaluation must run independently
EVALUATING → RUNNING	Re-running merge would invalidate evaluation state
COMPLETED → RUNNING	Completed experiments are immutable
ARCHIVED → any state	Archival is terminal; clone experiment to restart
FAILED → RUNNING	Failed experiments must be cloned, not resumed
CANCELLED → RUNNING	Cancelled experiments must be cloned, not resumed

Operator Actions by State

State	Allowed Actions	Prohibited Actions
CREATED	Edit configuration, delete experiment, start preparation	Start execution, view partial results
PREPARING	Cancel experiment, view import logs	Edit configuration, skip validation
RUNNING	Cancel experiment, view progress metrics, view logs	Edit configuration, force evaluation
EVALUATING	Cancel experiment, view benchmark progress, view logs	Edit configuration, skip benchmarks
COMPLETED	Archive experiment, clone experiment, export results, view full report	Edit configuration, restart execution
FAILED	Archive experiment, clone experiment, view error logs, view partial results	Restart execution, edit configuration
CANCELLED	Archive experiment, clone experiment, view logs	Restart execution, edit configuration
ARCHIVED	View read-only report, export results, delete after retention	All mutating actions

State Persistence

Experiment states are stored in ExperimentTracker as append-only log entries. Each transition records:

• Previous state
• New state
• Timestamp (UTC)
• Trigger (system event or operator command)
• Associated artifact references

This log is signed at each transition to prevent tampering.

Next Steps

See Experiment Tracking for the logging and persistence details, or Data Flow Map for the data classes that move through these states.