rerun-io--rerun/docs/content/reference/migration/migration-0-31.md

title, order

title	order
Migrating from 0.30 to 0.31	979

CLI

MCAP "layers" renamed to "decoders"

The -l / --layer flag for rerun mcap convert has been renamed to -d / --decoder.

This change is motivated by the ambiguity of the term "layer", which is also a core concept of the Rerun catalog server.

Before:

rerun mcap convert input.mcap -l protobuf -l stats -o output.rrd
rerun mcap convert input.mcap -l ros2msg -l raw -l recording_info -o output.rrd

After:

rerun mcap convert input.mcap -d protobuf -d stats -o output.rrd
rerun mcap convert input.mcap -d ros2msg -d raw -d recording_info -o output.rrd

When no -d flags are specified, all available decoders are still used by default (same behavior as before).

Server / catalog API

address renamed to url or host

Several server and catalog APIs have been renamed for clarity:

• CLI: rerun server --address … is now rerun server --host …
• Python rr.Server: The addr constructor argument is now host, and the address method is now url
• Python rr.CatalogClient: The address parameter is now url

Entry.update() deprecated in favor of Entry.set_name()

The Entry.update() method has been deprecated. Use Entry.set_name() instead for renaming entries:

# Before (deprecated)
entry.update(name="new_name")

# After
entry.set_name("new_name")

Rust API

re_mcap: Layer types renamed to Decoder

All public types in the re_mcap crate have been renamed from Layer to Decoder.

Old name	New name
Layer	Decoder
MessageLayer	MessageDecoder
LayerIdentifier	DecoderIdentifier
LayerRegistry	DecoderRegistry
SelectedLayers	SelectedDecoders

The layers module has been renamed to decoders (e.g., re_mcap::layers::McapRawLayer is now re_mcap::decoders::McapRawDecoder).

McapLoader API updated

McapLoader::new() now takes SelectedDecoders instead of SelectedLayers:

// Before
McapLoader::new(SelectedLayers::All)

// After
McapLoader::new(SelectedDecoders::All)