Added selection-aware word count plugin for Koenig

[kevinfengcs88]

Discussed with Steve (@9larsons) over Ghost support email, who suggested opening this in the Koenig repo.

Adds a headless SelectionWordCountPlugin that reports the word count of the current selection. onChange(count) fires with an integer (so a word count of 0 is allowed) while a non-collapsed range selection exists, and with null once the selection collapses.

• Counting reuses the same countWords util as WordCountPlugin, so selection counts should stay consistent with the document total
• Selections inside nested editors (image captions, callouts) work through the same context-ref pattern WordCountPlugin uses in KoenigNestedComposer
• This is purely additive. WordCountPlugin and its API are not touched
• The demo app renders "X of Y words" while text is selected (e.g. "2 of 9 words", and "0 of 9 words" for a whitespace-only selection). e2e coverage spans selection, whitespace, partial-word fragments, nested editors, select-all parity, and collapse.

Video demo:

ghost_koenig_word_counter.mp4

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 29916f7e-c645-4193-981c-a17789e1da69

📥 Commits

Reviewing files that changed from the base of the PR and between 1b37e67 and 017f74f.

📒 Files selected for processing (7)

• packages/koenig-lexical/demo/DemoApp.jsx
• packages/koenig-lexical/demo/components/WordCount.jsx
• packages/koenig-lexical/src/components/KoenigComposer.jsx
• packages/koenig-lexical/src/components/KoenigNestedComposer.jsx
• packages/koenig-lexical/src/index.js
• packages/koenig-lexical/src/plugins/SelectionWordCountPlugin.jsx
• packages/koenig-lexical/test/e2e/plugins/SelectionWordCountPlugin.test.js

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Walkthrough

This PR adds a new SelectionWordCountPlugin to track word counts of active text selections in Lexical editors. The plugin registers update listeners to monitor selection state, computes word counts for non-collapsed selections, and emits deduplicated combined counts across editor instances using shared composer refs with 200ms throttling. The feature is wired into the Koenig composer infrastructure through context-exposed refs, mounted in demo editor flows, integrated into the WordCount UI component, and validated with comprehensive e2e tests covering single and nested editor selection scenarios.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding a selection-aware word count plugin for Koenig, which is the primary purpose of this changeset.
Description check	✅ Passed	The description is well-related to the changeset, explaining the plugin's purpose, behavior, implementation details, and test coverage with concrete examples.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kevinfengcs88]

@9larsons

tagging you because I don't think I have the power to add you as a reviewer as an external contributor

Thanks!

[9larsons]

Thanks! I'll take a look when I'm able.