feat(investigations): Add entry points to block comment threads

[wedamija]

We're adding comments to Investigations, and this is one of a series of frontend PRs that build the feature. Comments show in an Activity section at the bottom of the page, and block comments open in a thread drawer. Everything is behind the investigations flag.

This PR adds more ways to open a block's thread:

• A comment button on each block. It stays visible when the block has comments, from a new comment-counts query.
• In the Activity feed, "Name commented on " links the block name to that comment in the drawer.
• These links switch an open drawer to the other thread instead of closing it.
• Text blocks use a grid layout so the button sits in the header.

Stacked on #127590. This is the last PR in the series.

[github-actions]

Story previews

Preview the stories changed in this PR on the Vercel deployment:

• app/views/investigations/detail/cell.stories.tsx
• app/views/investigations/detail/index.stories.tsx

_{Preview deployment: https://sentry-14vof8wx3.sentry.dev}

[sentry]

Sentry Snapshot Testing

Name	Added	Removed	Changed	Renamed	Unchanged	Skipped	Status
sentry-frontend sentry-frontend	0	0	0	0	630	0	✅ Unchanged

⚙️ sentry-frontend Snapshot Settings

[billyvg]

🤖 AI review by Claude, an AI agent. I'm reviewing this stack at @billyvg's request and wrote the inline comments below. @wedamija, Billy will also go through these comments and the code, so please treat this as a first pass, not a final review.

This looks good overall. My notes are about the comment button on archived investigations, making the comment count available to screen readers, and two explanatory comments that the refactor dropped.

[billyvg]

🤖 Nit: This refactor dropped the comment that explained why query cells use zero ("A query cell's header is SeerEmbedBlock's band, which is sized to its zero toggle; an xs trigger would make it taller than an embed's."). It now applies to both buttons, so it's worth keeping on actionSize. The same goes for the comment on the placeholder's paddingBottom="xl" (line 314), which still applies.

[cursor]

Stale Bugbot comment from a previous run.

[cursor]

Stale Bugbot comment from a previous run.

[billyvg]

Visual QA

Screenshots from Scraps stories (fixture data, 1440×900, light theme). "Before" is the #127590 head with the same stories and data.

Story coverage: comment-counts wasn't handled by the stories' fixture, so the pinned button never showed. The fixture now serves counts, and detail/cell.stories.tsx has a "Comment button" story. That's in a local commit that isn't pushed yet.

Headless Chrome matches (hover: none), which triggers the cells' touch rule (actions always visible). Both sides of these pairs are in that mode:

before	after

With a mouse pointer (--blink-settings=primaryHoverType=2):

at rest	hovering the first block

page at rest	Activity link with a thread open

Checked in the browser:

• The button is pinned on commented blocks and appears only on hover otherwise.
• Block names in Activity are links. With a thread open, a link switches to the other block's thread instead of closing the drawer.
• The text-block overlap ("…" over "time out.") is gone.

Nit: one-line text blocks grow about 3.6px. The action column is height="1lh" (19.6px), but one-line text content renders 16px tall, so the row grows to 19.6px and the button centres sit about 1.8px below the text's centre.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit bed73ab. Configure here.}

[cursor]

Actions miss first-line alignment

Low Severity

The overlay Flex sets height="0" so the hidden Text can size the row to one markdown line, but as a grid item it still has min-height: auto. That keeps the row as tall as the buttons, so they stay top-aligned instead of centering on the first line.

 

^{Reviewed by Cursor Bugbot for commit bed73ab. Configure here.}