Support Blockly 13 (blocked: peerDeps <12 + FocusManager / IFocusableTree)

[SebCanet]

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Problem

We would like to use @mit-app-inventor/blockly-plugin-workspace-multiselect with Blockly 13.x. Today the published package is incompatible both at the dependency level and at the runtime API level introduced in Blockly 12+.

Context: BlocklyDuino will be updated with blockly@^13.2.1 and the official @blockly/* plugins at ^13.2.0. Multiselect cannot be adopted until the plugin supports that line.

Current package constraints

Item	Value
Package	@mit-app-inventor/blockly-plugin-workspace-multiselect@1.0.2
Declared peer dependency	blockly: ">=11 <12"
Our app	blockly@^13.2.1

npm therefore rejects (or warns on) installation alongside Blockly 13 without overrides/forcing, and even with an override the plugin is not known to work.

Runtime breakage (Blockly 12+, still relevant for 13)

Already reported for Blockly 12 in #103:
TypeError: Cannot read properties of null (reading 'canBeFocused') at FocusManager.focusNode at Object.setSelected at MultiselectControls.updateMultiselect at Multiselect.eventListenerAll_

Maintainer note on #103: MultiselectDraggable needs to implement IFocusableTree for Blockly 12’s focus system.

So the incompatibility is not only a semver peer range: the plugin still assumes the pre–FocusManager selection model from Blockly 11.

Related work

• cannot be used normally in Blockly 12 #103 — cannot be used normally in Blockly 12
• Update to Blockly 12 #133 — Update to Blockly 12 (draft / WIP as of last check)
• There is currently no published release targeting Blockly 12, and no tracked support for Blockly 13.

Request

1. Land Blockly 12 support (Update to Blockly 12 #133 / successor) and publish a release with an updated peer range (e.g. >=12 <13 or whatever is accurate).
2. Plan / track Blockly 13 compatibility (peerDeps + any further API breaks after the focus-manager work).
3. Optionally document known conflicts with other plugins (e.g. official @blockly/plugin-cross-tab-copy-paste), since hosts on Blockly 13 often enable that plugin by default.

I hope this could help, many thanks!

Alternatives considered

No response

Additional context

No response