Notes: keep a floating thread in place when its block is hidden

[adamsilverstein]

Rebuilt on top of #83485 with Claude, which also rewrote this description:

Fixes #73565

When a block carrying a note is hidden at the current viewport, block.js renders nothing for it as soon as it is deselected. The thread then has no element to anchor to. Since #83485 the thread no longer drops to the top of the notes panel - it stays invisible until the block is selected. That keeps it out of the way, but the note disappears from the floating view for as long as its block is hidden.

This gives those threads a stand-in anchor: the gap the hidden block leaves between its rendered neighbours. That spot is not arbitrary - it is exactly where the block sits when it is selected, since a selected hidden block is still rendered, just collapsed to zero height so the block toolbar keeps working. Anchoring there means the thread does not shift when you click it.

The thread also says why it is not pointing at anything. "Block is hidden." is the same phrase the block inspector already uses, and the thread's accessible name becomes "Note on hidden block: ..." so screen reader users get the same context.

How it fits the board store

Following the suggestion in #73565 (comment), the fallback lives next to getNoteAnchorRect, in the board store's single measurement pass, so it adds no extra DOM reads or timers:

• Each thread registers its block's client ID along with its elements, and useFloatingBoard hands the store the document's block order (getClientIdsWithDescendants).
• In measure(), a thread with no block element gets its anchor from getHiddenBlockAnchorRect, which walks to the nearest rendered block on each side and returns the midpoint of the gap. A hidden last block falls back to the bottom of the block before it, a hidden first block to the top of the block after it.
• Neighbours that fail checkVisibility() are skipped, for the same reason Notes: Refactor floating board measurement #83485 climbs out of a closed Details block: collapsed content still reports its expanded box.
• The store finds the canvas root by climbing from a registered block. When every noted block is hidden there is none, so it looks the root up from the threads' document instead (the editor-canvas iframe, or the same document when the canvas is not iframed).

On the [Status] Blocked label

The issue is blocked on #73838 (hidden blocks should still be visible in the editor), which is still in discussion. This fix does not depend on how that lands: it only kicks in when a noted block has no rendered element. If hidden blocks later render as ghosts, or anything else visible, useBlockElement returns a real element and this path never runs. Suggest removing the blocked label.

The other two scenarios in the original issue - block transform and Group wrapping - were fixed by #77433, so this covers what was left.

How has this been tested?

Manually, in a wide viewport so the floating notes panel is active:

1. Add three paragraphs: a long one, then "Noted paragraph", then "Trailing paragraph".
2. Select the second paragraph and add a note. Confirm the thread lines up with the block.
3. With that block still selected, Options -> Hide, check "Hide on Desktop", Apply, then press Escape.
4. Click the first paragraph to deselect. On trunk the thread disappears. With this change it holds the gap where the block was, and reads "Block is hidden."
5. Click the thread. It expands in place and keeps the notice.
6. With the block still selected, Options -> Show, uncheck "Hide on Desktop", Apply. Deselect, and the thread realigns with the block.

Automated:

• Three Playwright tests in a new "Hidden blocks" group in test/e2e/specs/editor/various/block-notes-floating.spec.js: the middle-block case, the select/show round trip, and a hidden last block that is the only noted block. All three fail with trunk's board store and pass with this change.
• Full block-notes-floating.spec.js (37 passed) and block-notes.spec.js (58 passed) runs locally.
• Unit tests for getHiddenBlockAnchorRect (including skipping collapsed content), a board-store test for a thread whose block isn't rendered, and the tie-breaking cases in calculateNotePositions.

Types of changes

Bug fix.

• Add getHiddenBlockAnchorRect to derive a boundary anchor for a block with no rendered element.
• Measure that anchor in the board store, which now tracks each thread's block client ID and the document's block order.
• Find the canvas root from the threads' document when no noted block is rendered.
• Show a "Block is hidden." notice on the thread and adjust its accessible name.

Open questions

• Copy: "Block is hidden." matches the inspector, but it could hint at the affordance instead, eg. "Block is hidden. Select it in the List View to show it."
• The notice does not distinguish per-viewport hiding from hidden-everywhere. One generic string felt like enough for now.

AI Use

Code and description both came out of a session with 🤖 Claude Code, including the rebuild on #83485. I will review and test.

[github-actions]

Size Change: +477 B (+0.01%)

Total Size: 7.92 MB

📦 View Changed

Filename	Size	Change
build/scripts/editor/index.min.js	581 kB	+455 B (+0.08%)
build/styles/editor/style-rtl.css	31.8 kB	+6 B (+0.02%)
build/styles/editor/style-rtl.min.css	27.2 kB	+4 B (+0.01%)
build/styles/editor/style.css	31.8 kB	+7 B (+0.02%)
build/styles/editor/style.min.css	27.2 kB	+5 B (+0.02%)

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[github-actions]

Flaky tests detected in 569b024.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/33116216951
📝 Reported tests:

refuses the drop and uploads nothing in /test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js, passed after 1 failed attempt.

Error: expect(received).toHaveLength(expected)

Expected length: 0
Received length: 2
Received array:  [{"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=110"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/110", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-110", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-08-27T21:12:59", "date_gmt": "2026-08-27T21:12:59", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK-1.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK-1.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK-1.png"}, "id": 110, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk-2/", "media_details": {"file": "2026/08/10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-08-27T21:12:59", "modified_gmt": "2026-08-27T21:12:59", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk-2", "source_url": "http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK-1.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}, {"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=106"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/106", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-106", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-08-27T21:12:39", "date_gmt": "2026-08-27T21:12:39", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK.png"}, "id": 106, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk/", "media_details": {"file": "2026/08/10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-08-27T21:12:39", "modified_gmt": "2026-08-27T21:12:39", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk", "source_url": "http://localhost:8889/wp-content/uploads/2026/08/10x10_e2e_test_image_z9T8jK.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}]
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js:71:45

[github-actions]

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Co-authored-by: adamsilverstein <adamsilverstein@git.wordpress.org>
Co-authored-by: Vrishabhsk <vrishabhsk@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
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📦 Bundle size

Size Change: +466 B (+0.01%)

Total Size: 8.51 MB

📦 View Changed

Filename	Size	Change
build/scripts/editor/index.min.js	637 kB	+445 B (+0.07%)
build/styles/editor/style-rtl.css	32.6 kB	+8 B (+0.02%)
build/styles/editor/style-rtl.min.css	27.7 kB	+3 B (+0.01%)
build/styles/editor/style.css	32.7 kB	+6 B (+0.02%)
build/styles/editor/style.min.css	27.7 kB	+4 B (+0.01%)

_{d000aa9 Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	f244704	trunk	% Change
timeToFirstByte	55.25 ms +10.77% -6.52%	53.5 ms +13.93% -2.9%	3.27%
largestContentfulPaint	96 ms +8.33% -6.25%	92 ms +4.35% -6.52%	4.35%
lcpMinusTtfb	38.8 ms +10.82% -12.24%	34.2 ms +26.46% -5.26%	13.45%
wpBeforeTemplate	28.57 ms +18.73% -2.42%	28.31 ms +15.05% -1.06%	0.92%
wpTemplate	21.79 ms +7.71% -6.56%	20.69 ms +9.28% -1.88%	5.32%
wpTotal	51.67 ms +10.92% -7.1%	49.96 ms +14.23% -2.94%	3.42%
wpMemoryUsage	7.61 MB +0% -0%	7.58 MB +0% -0%	0.46%
wpDbQueries	17 +0% -0%	17 +0% -0%	0%

front-end-classic-theme

Metric	f244704	trunk	% Change
timeToFirstByte	45.15 ms +7.75% -0.78%	41.5 ms +8.8% -2.41%	8.8%
largestContentfulPaint	100 ms +6% -0%	92 ms +0% -4.35%	8.7%
lcpMinusTtfb	54.95 ms +1.64% -2.82%	47.5 ms +5.79% -2%	15.68%
wpBeforeTemplate	26.05 ms +5.68% -1.54%	26.4 ms +6.93% -1.63%	-1.33%
wpTemplate	16.13 ms +2.85% -2.11%	12.21 ms +3.28% -2.38%	32.1%
wpTotal	42.09 ms +8.08% -0.88%	38.74 ms +9.03% -2.43%	8.65%
wpMemoryUsage	6.25 MB +0% -0%	6.10 MB +0% -0%	2.4%
wpDbQueries	14 +0% -0%	10 +0% -0%	40%

media-processing

Metric	f244704	trunk	% Change
mediaProcessingJpeg	396.47 ms +2.52% -0.37%	400.44 ms +0.97% -1.18%	-0.99%
mediaProcessingAvif	6048.03 ms +0.4% -0.03%	6076.55 ms +0.18% -0.16%	-0.47%
mediaProcessingJpegToAvif	4183.75 ms +0.22% -0.18%	4196.84 ms +0.17% -0.19%	-0.31%

media-upload

Metric	f244704	trunk	% Change
jpegUploadProcessing	1430.79 ms +36.33% -0.72%	1434.48 ms +0.72% -0.6%	-0.26%
pngUploadProcessing	192.06 ms +9.94% -8.81%	223 ms +7.81% -11.87%	-13.87%
largeJpegUploadProcessing	1415.28 ms +0.4% -0.8%	1410.91 ms +0.79% -0.47%	0.31%
multipleImageUploadProcessing	1564.74 ms +1.79% -0.74%	1603.24 ms +9.03% -2.84%	-2.4%

post-editor

Metric	f244704	trunk	% Change
serverResponse	320.99 ms +3.31% -8.62%	325.47 ms +4.98% -10.33%	-1.38%
firstPaint	184.73 ms +8.21% -6.02%	170.36 ms +12.3% -7.53%	8.44%
domContentLoaded	872.77 ms +1.77% -0.59%	871.34 ms +2.57% -2.75%	0.16%
loaded	873.85 ms +1.76% -0.6%	872.38 ms +2.6% -2.73%	0.17%
firstContentfulPaint	378.17 ms +2.57% -1.51%	378.94 ms +0.68% -4.45%	-0.2%
firstBlock	2543.24 ms +1.09% -0.39%	2548.64 ms +0.88% -2.07%	-0.21%
type	16.34 ms +2.75% -7.83%	15.77 ms +5.39% -2.16%	3.61%
typeWithoutInspector	15.72 ms +2.99% -3.82%	16.33 ms +3.92% -4.9%	-3.74%
typeWithTopToolbar	18.64 ms +2.63% -1.07%	19.98 ms +4.5% -3%	-6.71%
typeContainer	7.35 ms +10.34% -2.99%	7.46 ms +11.13% -4.42%	-1.47%
focus	89.15 ms +7.28% -7.36%	92.6 ms +10.76% -4.14%	-3.73%
firstFocus	170.3 ms +0% -0%	171.75 ms +0% -0%	-0.84%
selectAll	462.79 ms +1.29% -3.24%	461.66 ms +4.61% -6.03%	0.24%
listViewOpen	60.98 ms +3.92% -6.13%	58.68 ms +5.47% -3.37%	3.92%
inserterOpen	33.8 ms +7.9% -8.17%	33.98 ms +6.97% -9.54%	-0.53%
inserterHover	9.57 ms +17.03% -9.51%	9.83 ms +7.73% -7.63%	-2.64%
inserterSearch	7.12 ms +5.76% -5.2%	7.26 ms +6.61% -5.65%	-1.93%
loadPatterns	507.98 ms +1.28% -1.66%	488.02 ms +8.37% -2.1%	4.09%
wpTotal	311.32 ms +2.99% -8.9%	315.81 ms +5.22% -10.69%	-1.42%
wpMemoryUsage	13.33 MB +0% -0%	13.30 MB +0% -0%	0.25%
wpDbQueries	54 +0% -1.85%	54 +0% -0%	0%

site-editor

Metric	f244704	trunk	% Change
serverResponse	513.63 ms +4.02% -6.4%	499.66 ms +3.76% -3.55%	2.8%
firstPaint	259.04 ms +26.46% -8.21%	258.15 ms +24.49% -10.45%	0.34%
domContentLoaded	1207.09 ms +2.6% -2.06%	1228.17 ms +1.38% -2.36%	-1.72%
loaded	1208.35 ms +2.6% -2.07%	1229.45 ms +1.41% -2.36%	-1.72%
firstContentfulPaint	484.7 ms +2.22% -1.28%	493.51 ms +2.21% -1.83%	-1.79%
firstBlock	4582.6 ms +0.63% -0.63%	4621.52 ms +0.85% -0.88%	-0.84%
type	18.34 ms +8.51% -2.67%	18.96 ms +4.59% -4.17%	-3.27%
navigate	127.17 ms +5.43% -6.72%	124.31 ms +11.2% -2.45%	2.3%
loadPatterns	1260.13 ms +3% -2.25%	1259.24 ms +3.58% -4.69%	0.07%
loadPages	1018.44 ms +2.11% -2.88%	1008.66 ms +0.95% -1.25%	0.97%
wpTotal	503.18 ms +3.98% -6.68%	488.56 ms +3.86% -3.71%	2.99%
wpMemoryUsage	12.38 MB +0% -0%	12.34 MB +0% -0%	0.3%
wpDbQueries	43 +2.33% -0%	43 +2.33% -0%	0%

_{d000aa9 Run}