041 Metrics API Client

Credential and host resolution follows the shared Metrics client credentials contract.

Python client for the 041 Metrics v2 API. Use it to find and organize folders and experiments and to read one experiment's record, catalog, annotations, and series from code.

Pick the right tool:

• Analysis across experiments: the o41-metrics-duckdb extension attaches Metrics as a database with an on-disk cache. Use it for plots, tables, joins, and anything spanning a folder.
• Recording training or evaluation jobs: o41-metrics-collector queues, batches, and delivers metrics in the background. This client's write session exists for API completeness, tests, and backfills.
• Programmatic control and one-experiment reads: this client.

Install

uv add o41-metrics-api

Connect

from o41_metrics_api import Metrics

metrics = Metrics()

The key comes from api_key=, then O41_METRICS_API_KEY, then SYVAIN_METRICS_API_KEY, then the login saved by o41-metrics auth login, like the o41-metrics CLI. A key goes only to the host it is paired with. An argument or environment key goes to host=, then O41_METRICS_HOST, then SYVAIN_METRICS_HOST, then https://metrics.041.io, never to the saved login's host. The saved login's key goes only to the host it was saved for; if host= or O41_METRICS_HOST names another one, Metrics() raises MetricsAuthError.

For example, if a saved login names https://custom.example.test, setting O41_METRICS_API_KEY alone sends that key to https://metrics.041.io.

Metrics is also a context manager that closes its HTTP session.

Folders and experiments

Address a folder by absolute path or id; / is the root. Address an experiment by id or slug.

mamba = metrics.make_folder("/models/mamba")  # creates missing parents
mamba = metrics.folder("/models/mamba")       # MetricsNotFound when missing
mamba.folders()                               # direct children
mamba.experiments()                           # direct members
mamba.experiments("run-*", recursive=True)    # slug glob, whole subtree
metrics.experiments("syv-2039-*")             # every experiment matching a glob

exp = metrics.experiment("mamba-run-001")
exp.move("/archive")
mamba.rename("mamba-v2")
mamba.move("/")

Lookups use a snapshot of the folder tree, read on first use. Changes made through the client refresh it. A folder() or experiment() lookup that misses reads the tree again once before raising. Listings such as folders() and experiments() use the snapshot as is, so call metrics.refresh() to list what was created elsewhere. Folder and Experiment are immutable values. A rename or move returns a new handle.

Read one experiment

info = exp.info()          # status, description, meta, error, lifecycle datetimes
catalog = exp.catalog()    # series names with their metadata keys and values
notes = exp.annotations()  # every annotation, newest first

for series in exp.series("loss", where={"split": "valid"}):
    print(series.metadata, series.steps, series.values)

series() returns one Series per metadata partition. Its steps, timestamps_ms, and values are aligned. Pass one name, several names, or none to read every series of the experiment. Results follow the order of the names, or name order when you pass none. One streaming request reads up to 1,000 series. where matches exact metadata values, has=("rank",) requires a key, and x="timestamp" orders points by time instead of step. The client returns series only after the stream completes, so partial data is never returned.

Write session

with metrics.open_experiment(
    "backfill-001", description="Imported run", meta={"seed": 7}, folder="/imports"
) as run:
    run.start()
    run.metric("loss", 0.25, step=1, metadata={"split": "train"})
    run.done()

Each call is one acknowledged request. metrics() takes many MetricPoints and sends up to 1000 per request. The session refreshes its experiment token before it expires and revokes the token when the block exits. Reopening an existing slug replaces its description and meta. An experiment already in another folder stays there. A token left idle past its 24 hour expiry cannot be refreshed, so reopen the experiment instead. For real training jobs use o41-metrics-collector.

Other events

metrics.send(event, data) sends any v2 organization event to /api/v2/events and returns the reply data. The API reference is at https://metrics.041.io/api/openapi.json.

Errors and retries

Every failure is a MetricsError with code, message, status, and retryable. MetricsNotFound (also a LookupError) reports an unresolved reference. MetricsAuthError reports missing credentials.

Reads and metric writes retry transient failures with backoff. A retried metric keeps its original message id, which the API deduplicates. Every other write never retries, because repeating it can have side effects: folder creation, moves, renames, open_experiment, lifecycle events (a replayed done would move done_at), annotations, and send().

ExperimentRun drops non-finite metric values with a warning and sends finite points in the same batch. Earlier releases raised ValueError for the whole batch. See the shared credentials contract for this compatibility change.