fix: forward on insert.text breaks undo batching

[christianhg]

Problem

When a behavior uses forward(event) on insert.text with a second action set, each typed character becomes its own undo step instead of merging with adjacent characters.

This breaks the expected undo behavior for any behavior that observes text insertion without modifying it (e.g., a behavior that forwards the text and then checks the block content to update styles).

Root cause

performEvent sets a unique undoStepId for every insert.text event because it's synthetic (not in nativeBehaviorEventTypes). Without custom behaviors, the default handler clears undoStepId before running the operation, so consecutive characters merge via the history plugin's merge heuristic. But when a behavior forwards the event, defaultBehaviorOverwritten = true and the clearing never happens. Each character gets a unique undoStepId, preventing history merge.

Fix

Add a merge heuristic in undo-step.ts for the case where consecutive operations have different defined undoStepIds. When both IDs are defined but different, and the operations are consecutive insert_text at adjacent offsets on the same path (or consecutive remove_text), merge them into the same undo step. This matches the existing merge behavior for the undefined ID case.

This approach avoids changing performEvent and preserves the existing undo step separation for:

• Custom events forwarding to insert.block (different op types, not insert_text)
• Input rule transformations (the transformation creates a new undo step boundary between the forwarded text and the rule application)

Testing

Two new browser tests verify the fix:

• Forwarding insert.text preserves undo batching
• Forwarding insert.text with side effect preserves undo batching

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Project	Deployment	Actions	Updated (UTC)
portable-text-editor-documentation	Ready	Preview, Comment	Feb 24, 2026 0:39am
portable-text-example-basic	Ready	Preview, Comment	Feb 24, 2026 0:39am
portable-text-playground	Ready	Preview, Comment	Feb 24, 2026 0:39am

[changeset-bot]

🦋 Changeset detected

Latest commit: cb518a9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@portabletext/editor	Patch
@portabletext/plugin-character-pair-decorator	Patch
@portabletext/plugin-emoji-picker	Patch
@portabletext/plugin-input-rule	Patch
@portabletext/plugin-markdown-shortcuts	Patch
@portabletext/plugin-one-line	Patch
@portabletext/plugin-paste-link	Patch
@portabletext/plugin-sdk-value	Patch
@portabletext/plugin-typeahead-picker	Patch
@portabletext/plugin-typography	Patch
@portabletext/toolbar	Patch

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