[fivestarspicy]

Problem

A person reading a Replay Vision observation sees **Checkout blocked at payment** with the asterisks, and a - in front of every bullet. Scanners already write a lead-in and a list when a finding has parts, and the Model reasoning card renders all of it as one flat paragraph, so the structure blends in.

Rendering markdown is the easy half. The same reasoning string feeds six surfaces that read it as one line of prose, and each collapses whitespace without stripping syntax. A markdown bullet arrives in a Slack alert as a literal - at the start of a line it does not own, and ** tokens go into the vectors that semantic search ranks on.

Changes

Surface	Before	After
Model reasoning card, dock (expanded)	Raw ** and -	Rendered markdown
Dock preview, seekbar marks	Raw ** and -	Flattened prose
Slack alerts, search snippets, synthesis feed, embeddings	Raw ** and -	Flattened prose

• The Model reasoning card renders bold, headings and lists, and its citations stay seek controls.
• The dock's collapsed preview shows flattened prose. line-clamp counts lines inside one block, so it cannot trim a rendered heading and list to two.
• Slack alert lines and the synthesis feed keep their one-line-per-observation shape. Recording-derived text still cannot forge a row or a header there, which flattening now enforces one step earlier than whitespace collapsing did.
• Search embeddings drop the syntax before the text is embedded.
• No link in reasoning is clickable. A scanner describes a recording and has no reason to link anywhere, and rendering markdown is what would otherwise turn a URL it picked up off a page into something a reader can click. LemonMarkdown gains disableLinks, which renders every link as its label; CitedMarkdown sets it. Enforced at the renderer rather than by stripping syntax, because markdown reaches a link through inline [x](url), reference [x][ref], a bare URL autolinked by remark-gfm, or an untrusted image falling back to a link — a sanitizer upstream of the parser has to out-guess all of them, while this never emits an anchor.
• LemonMarkdown gains renderTimestampRef, a t:<ms> link target that mirrors the existing chart: reference. A remark plugin was the alternative; the link target reuses a mechanism already in the component and degrades to a readable timestamp where no player is on screen.
• Mechanical: the citation chip moves out of CitedText into TimestampCitation, shared by both renderers.

Note

The scanner prompts are unchanged and still ask for one paragraph. The model already writes structure sometimes, which is what this PR renders. Loosening the prompt is a follow-up, so it can be measured against a UI that already shows the difference.

Before and after, from the new Storybook story:

How did you test this code?

react-markdown is mocked in Jest because it is ESM-only, so no Jest test can prove the rendering works. The stories were rendered in headless Chromium against a local Storybook instead: bold became <strong>, bullets became <ul><li>, both citations became seek buttons, and the page reported no anchors and no errors.

The no-clickable-link property is guarded by the HostileLinks story, whose play asserts zero anchors and runs in a real browser under test-storybook in CI. Both halves of that guard were checked rather than assumed: inverting the assertion made it fail from play, and removing disableLinks brought back 5 live anchors — the inline link, [click here][ref], ![a banner][img] via the untrusted-image link fallback, the autolink, and the bare URL. So the fixture reproduces the exposure and the assertion catches it.

New tests and the regression each catches:

• plain_snippet cases in test_observation_formatting.py: a bullet list reaching a Slack alert or the synthesis feed as a literal - row, and snake_case or 3 * 4 being eaten as emphasis. Extended the existing forgery test rather than adding a second one.
• flatten_markdown keeping paragraph breaks: embeddings take the whole flattened string, so a strip that also folded the lines would change what is indexed.
• citedMarkdown cases in citations.test.ts: a bullet or bold run that spans a citation being cut into two markdown documents, a citation after a ! parsing as an image, and the prose being altered on its way to the renderer now that sanitizing is the renderer's job.
• Flattener reference-link cases: a [x][ref] usage reaching a Slack alert with its brackets intact, and the inverse — a sentence like [Save]: clicked twice before it took being mistaken for a link reference definition and dropped.

Not run: the full backend suite. The affected files were covered locally against Postgres and ClickHouse.

Automatic notifications

• Publish to changelog?

Docs update

None. No documented workflow changes.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Written by the PostHog Slack app (Claude Opus) from a request in a Slack thread asking whether the Model reasoning field could use markdown, and to cover the full stack without cluttering the Scouts or Alerts flow.

Skills invoked: /writing-tests, /writing-ui-components, /writing-pr-descriptions.

Two decisions worth flagging. A bespoke renderer inside the product was the first design; the react/forbid-elements lint rule reserves ReactMarkdown to LemonMarkdown, which settled it in favour of extending the shared component. Link handling started as regex defanging of the source; review (1, 2) showed reference links went straight through it, so it moved to the render boundary and the regexes came out.

All sample text in the tests, the story and the screenshots is invented. No customer material was used.

---

Created with PostHog from a Slack thread

[trunk-io]

😎 Merged successfully - details.

[github-actions]

🦔 Hogbox preview · ✅ ready

▶ Open the preview

🔑 Login	test@posthog.com / 12345678 (demo data)
🧩 Running	this PR's backend and frontend, on the PostHog :master base
🔗 Link	stable across rebuilds — a re-push swaps the box underneath, the URL stays
🔒 Access	tailnet only (PostHog VPN)
🛠️ Admin	inspect & debug state in hogland
💤 Idle	sleeps after ~30 min idle (snapshot to S3, zero node cost) and wakes on your next visit in ~30s, behind a brief "waking up" screen

_{commit 1364295 · box box-2932c8261f91 · ready in 1018s (push → usable) · build log · rebuilds on every push, torn down on close}

[github-actions]

🤖 CI report

⚠️ Trunk lane — backend Python lane

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

⚠️ Complexity (TypeScript) — 6 functions above the limit (max 98)

Cyclomatic complexity above the limit in changed typescript files (10 for production files, 15 for test files). Warn only: worth simplifying when you next touch these functions.

Function	Location	Complexity	Limit
ReplayObservationSceneComponent	products/replay_vision/frontend/observations/ReplayObservation.tsx:144	98	10
ObservationPrimaryOutput	products/replay_vision/frontend/components/ObservationCard.tsx:114	53	10
ObservationDockCard	products/replay_vision/frontend/components/ObservationCard.tsx:401	20	10
observationClipboardText	products/replay_vision/frontend/utils/observation.ts:218	17	10
ReplayVisionScanWidget	products/posthog_ai/frontend/components/tool/widgets/ReplayVisionScanWidget.tsx:32	12	10
ObservationStatusTag	products/replay_vision/frontend/components/ObservationCard.tsx:27	12	10

⚠️ Comment density — 5% of added code lines are comments (27 of 510)

This section warns when comments are more than 3% of the code lines a PR adds, and alerts above 6%. Before agent-assisted PRs, the typical share was about 2%. Only full-line comments count. Docstrings, generated files, snapshots, migrations, and workflow files are left out.

Comments that restate the code, record how the change came about, or narrate the next line add noise for the next reader. Keep the comments that explain a reason the code cannot show, and remove the rest. See .agents/skills/writing-code-comments/SKILL.md for the house rules.

Files with the most added comment lines:

File	Comment lines	Added lines
frontend/src/lib/lemon-ui/LemonMarkdown/LemonMarkdown.tsx	10	55
products/replay_vision/frontend/utils/citations.ts	6	24
products/replay_vision/frontend/components/CitedMarkdown.stories.tsx	4	70
products/replay_vision/frontend/components/CitedMarkdown.tsx	2	29
products/replay_vision/frontend/utils/markdown.ts	2	46
products/posthog_ai/frontend/components/tool/widgets/ReplayVisionScanWidget.tsx	1	4
products/replay_vision/frontend/components/TimestampCitation.tsx	1	22
products/replay_vision/frontend/utils/observation.ts	1	6

This check does not block merging. It updates on every push and clears when the share drops.

⚠️ Bundle size — 🔺 +492 B (+0.0%)

Uncompressed size of every built .js bundle, compared against the base branch.

Total: 68.65 MiB · 🔺 +492 B (+0.0%)

No file changed by more than 1000 B.

_{Posted automatically by build-bundle-size-report · uncompressed bytes from dist-report}

✅ Eager graph — within budget

How much code each root ships on the eager path — downloaded and parsed before the surface is interactive. Measured from the esbuild output chunks (post-tree-shake, static imports only); lazy import() / React.lazy chunks are not counted.

Root	Eager (shipped)	Δ vs base	Budget
entry (logged-out pages, app bootstrap) src/index.tsx	1.50 MiB · 22 files	no change	███░░░░░░░ 33.2% of 4.51 MiB
logged-out boot: index + App + bootApp (preloaded by every page, including /login) src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts	5.24 MiB · 668 files	no change	█████████░ 93.1% of 5.63 MiB
authenticated shell (every logged-in page) src/scenes/AuthenticatedShell.tsx	7.66 MiB · 2,677 files	🔺 +550 B (+0.0%)	█████████░ 87.3% of 8.77 MiB

🟢 node_modules/monaco-editor/ stays out of src/index.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 node_modules/monaco-editor/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/layout/navigation-3000/navigationLogic.tsx stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 src/scenes/dashboard/dashboardLogic.tsx stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
🟢 node_modules/monaco-editor/ stays out of src/scenes/AuthenticatedShell.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 src/scenes/session-recordings/player/sessionRecordingPlayerLogic.ts stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx

Largest files eagerly shipped from src/index.tsx

Size	File
126.8 KiB	../node_modules/.pnpm/react-dom@18.3.1_react@18.3.1/node_modules/react-dom/cjs/react-dom.production.min.js
24.6 KiB	../node_modules/.pnpm/buffer@6.0.3/node_modules/buffer/index.js
6.3 KiB	../node_modules/.pnpm/react@18.3.1/node_modules/react/cjs/react.production.min.js
4.5 KiB	../node_modules/.pnpm/@jspm+core@2.1.0/node_modules/@jspm/core/nodelibs/browser/process.js
3.9 KiB	../node_modules/.pnpm/scheduler@0.23.2/node_modules/scheduler/cjs/scheduler.production.min.js
1.4 KiB	../node_modules/.pnpm/base64-js@1.5.1/node_modules/base64-js/index.js
1.3 KiB	src/RootErrorBoundary.tsx
1.0 KiB	src/index.tsx
912 B	../node_modules/.pnpm/ieee754@1.2.1/node_modules/ieee754/index.js
854 B	src/scenes/ChunkLoadErrorBoundary.tsx

Largest files eagerly shipped from src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts

Size	File
281.8 KiB	../node_modules/.pnpm/posthog-js@1.428.6_@types+react@18.3.27_react@18.3.1/node_modules/posthog-js/dist/module.mjs
267.7 KiB	../node_modules/.pnpm/@posthog+icons@0.38.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js
255.4 KiB	src/taxonomy/core-filter-definitions-by-group.json
126.8 KiB	../node_modules/.pnpm/react-dom@18.3.1_react@18.3.1/node_modules/react-dom/cjs/react-dom.production.min.js
104.2 KiB	src/lib/api.ts
79.0 KiB	src/products.tsx
68.8 KiB	src/lib/lemon-ui/icons/icons.tsx
62.5 KiB	src/lib/utils/eventUsageLogic.ts
38.8 KiB	../node_modules/.pnpm/@dnd-kit+core@6.0.8_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@dnd-kit/core/dist/core.esm.js
33.9 KiB	../node_modules/.pnpm/kea@4.0.0-pre.6_patch_hash=139b8d1f1304f9d9da452a9a1244c94ea679dbcb85687d8999563146879fb6f5_react@18.3.1/node_modules/kea/lib/index.cjs.js

Largest files eagerly shipped from src/scenes/AuthenticatedShell.tsx

Size	File
281.8 KiB	../node_modules/.pnpm/posthog-js@1.428.6_@types+react@18.3.27_react@18.3.1/node_modules/posthog-js/dist/module.mjs
267.7 KiB	../node_modules/.pnpm/@posthog+icons@0.38.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js
255.4 KiB	src/taxonomy/core-filter-definitions-by-group.json
153.8 KiB	../node_modules/.pnpm/re2js@0.4.1/node_modules/re2js/build/index.esm.js
126.8 KiB	../node_modules/.pnpm/react-dom@18.3.1_react@18.3.1/node_modules/react-dom/cjs/react-dom.production.min.js
104.2 KiB	src/lib/api.ts
95.8 KiB	../packages/quill/packages/quill/dist/index.js
93.3 KiB	../node_modules/.pnpm/prosemirror-view@1.40.1/node_modules/prosemirror-view/dist/index.js
90.6 KiB	../node_modules/.pnpm/@tiptap+core@3.20.6_@tiptap+pm@3.20.6/node_modules/@tiptap/core/dist/index.js
79.0 KiB	src/products.tsx

_{Posted automatically by check-eager-graph · sizes are eager output bytes (shipped, post-tree-shake) from the esbuild metafile · part of #32479}

✅ Toolbar bundle — eager 2.29 MiB within budget

What the toolbar ships to customer pages, measured from the esbuild output (minified, post-tree-shake). The eager set is the entry plus everything statically imported from it — fetched before any feature runs; deferred chunks load lazily. The eager guardrail is 5.72 MiB. Each output file must also stay below 10 MB, where CloudFront stops compressing it. The module boundary is enforced separately by check-toolbar-graph.

Metric	Size	Δ vs base	Budget
Eager (shipped) entry + static imports	2.29 MiB · 18 files	no change	████░░░░░░ 40.0% of 5.72 MiB
Deferred (lazy)	2.11 MiB · 45 files	no change	n/a — loads on demand
Loader dist/toolbar.js	1.1 KiB	no change	█░░░░░░░░░ 5.8% of 19.5 KiB

Largest eagerly-shipped chunks

Size	File
756.4 KiB	dist/toolbar/toolbar-app-LA4JX7FS.css
608.8 KiB	dist/toolbar/chunk-chunk-P3PF5T4P.js
484.7 KiB	dist/toolbar/chunk-chunk-RPV3NYRJ.js
136.6 KiB	dist/toolbar/chunk-chunk-6MQWLXON.js
131.8 KiB	dist/toolbar/chunk-chunk-FDH2IBXT.js
72.2 KiB	dist/toolbar/toolbar-app-VLT4VAGU.js
69.0 KiB	dist/toolbar/chunk-chunk-TSAL54PB.js
35.6 KiB	dist/toolbar/chunk-chunk-DTB5C7AH.js
21.0 KiB	dist/toolbar/chunk-chunk-35CVENAR.js
6.8 KiB	dist/toolbar/chunk-chunk-DV7IWQNF.js

_{Posted automatically by check-toolbar-size · sizes are toolbar output bytes (shipped, post-tree-shake) from the esbuild metafile}

✅ Dist folder size — 🔺 +26.9 KiB (+0.0%)

Total size of the built frontend/dist folder (all assets), compared against the base branch.

Total: 1458.18 MiB · 🔺 +26.9 KiB (+0.0%)

⚠️ Playwright — 1 flaky

🎭 Playwright report · View test results →

⚠️ 1 flaky test:

• Add a funnel insight, configure steps, and verify conversion rates (chromium)

These issues are not necessarily caused by your changes.
Annoyed by this section? Help fix flakies and failures and it will go green!

✅ Backend coverage — all changed backend lines covered

🧪 Backend test coverage

Patch coverage — changed backend lines (products + core): ████████████████████ 100.0% (62 / 62)

All changed backend lines are covered ✅

Per-product line coverage (touched products)

Product	Coverage	Lines
platform_features	██░░░░░░░░░░░░░░░░░░ 12.1%	7 / 58
warehouse_sources_queue	██████░░░░░░░░░░░░░░ 29.1%	92 / 316
data_tools	████████████░░░░░░░░ 62.1%	90 / 145
demo	████████████░░░░░░░░ 62.1%	1,660 / 2,671
ai_gateway	███████████████░░░░░ 75.0%	9 / 12
batch_exports	████████████████░░░░ 80.1%	19,507 / 24,368
apm	█████████████████░░░ 83.3%	1,234 / 1,481
wizard	█████████████████░░░ 85.3%	2,779 / 3,259
cdp	█████████████████░░░ 85.4%	4,349 / 5,094
signals	█████████████████░░░ 85.5%	36,471 / 42,645
product_tours	██████████████████░░ 88.0%	1,312 / 1,491
notebooks	██████████████████░░ 88.5%	11,879 / 13,429
data_warehouse	██████████████████░░ 88.9%	12,824 / 14,424
business_knowledge	██████████████████░░ 89.2%	4,469 / 5,008
cohorts	██████████████████░░ 89.3%	7,543 / 8,450
dashboards	██████████████████░░ 89.6%	6,837 / 7,631
engineering_analytics	██████████████████░░ 90.1%	8,391 / 9,310
streamlit_apps	██████████████████░░ 90.2%	2,517 / 2,790
tasks	██████████████████░░ 90.3%	65,989 / 73,098
data_modeling	██████████████████░░ 90.4%	9,350 / 10,347
managed_warehouse	██████████████████░░ 90.7%	9,417 / 10,378
exports	██████████████████░░ 90.8%	9,123 / 10,050
alerts	██████████████████░░ 90.9%	5,242 / 5,765
links	██████████████████░░ 91.0%	192 / 211
mcp_analytics	██████████████████░░ 91.2%	4,411 / 4,837
canvas	██████████████████░░ 91.3%	5,033 / 5,514
conversations	██████████████████░░ 91.3%	21,739 / 23,816
visual_review	██████████████████░░ 91.7%	7,567 / 8,250
error_tracking	██████████████████░░ 92.0%	13,495 / 14,669
notifications	██████████████████░░ 92.5%	1,120 / 1,211
early_access_features	███████████████████░ 92.6%	1,331 / 1,438
managed_migrations	███████████████████░ 92.7%	1,576 / 1,700
slack_app	███████████████████░ 92.7%	12,684 / 13,676
surveys	███████████████████░ 93.1%	6,180 / 6,640
mcp_registry	███████████████████░ 93.2%	1,471 / 1,578
web_analytics	███████████████████░ 93.3%	19,324 / 20,706
stamphog	███████████████████░ 93.4%	6,543 / 7,009
context_layer	███████████████████░ 93.4%	2,616 / 2,801
mcp_store	███████████████████░ 93.5%	8,063 / 8,621
reminders	███████████████████░ 93.5%	477 / 510
marketing_analytics	███████████████████░ 93.5%	17,452 / 18,657
posthog_ai	███████████████████░ 93.6%	1,395 / 1,491
ai_observability	███████████████████░ 93.8%	18,255 / 19,463
approvals	███████████████████░ 93.9%	3,570 / 3,803
billing_alerts	███████████████████░ 94.1%	2,079 / 2,210
endpoints	███████████████████░ 94.2%	9,072 / 9,627
review_hog	███████████████████░ 94.3%	10,214 / 10,826
tracing	███████████████████░ 94.5%	2,726 / 2,885
legal_documents	███████████████████░ 94.7%	2,082 / 2,199
workflows	███████████████████░ 94.7%	11,801 / 12,455
autoresearch	███████████████████░ 95.0%	934 / 983
customer_analytics	███████████████████░ 95.1%	19,308 / 20,303
annotations	███████████████████░ 95.3%	804 / 844
product_analytics	███████████████████░ 95.3%	19,328 / 20,280
actions	███████████████████░ 95.4%	749 / 785
replay_vision	███████████████████░ 95.5%	22,800 / 23,868
skills	███████████████████░ 95.6%	5,536 / 5,791
experiments	███████████████████░ 95.6%	30,259 / 31,643
access_control	███████████████████░ 95.7%	6,247 / 6,527
feature_flags	███████████████████░ 95.7%	20,313 / 21,220
messaging	███████████████████░ 95.9%	3,680 / 3,839
growth	███████████████████░ 96.0%	7,728 / 8,053
logs	███████████████████░ 96.0%	13,950 / 14,532
revenue_analytics	███████████████████░ 96.3%	1,841 / 1,911
user_interviews	███████████████████░ 96.5%	2,651 / 2,747
warehouse_sources	███████████████████░ 97.2%	409,791 / 421,671
data_quality	████████████████████ 97.6%	4,229 / 4,335
analytics_platform	████████████████████ 98.2%	2,381 / 2,425
metrics	████████████████████ 98.2%	3,576 / 3,640
data_catalog	████████████████████ 98.3%	3,267 / 3,322
pulse	████████████████████ 98.4%	2,028 / 2,060
live_debugger	████████████████████ 99.2%	621 / 626
field_notes	████████████████████ 99.4%	167 / 168

Report-only. Patch coverage = changed backend lines covered vs origin/master. Sorted lowest first.
Known gaps: lines covered only by Temporal tests show as uncovered; core line numbers may drift if master changed the same file.

[veria-ai]

PR overview

All previously flagged issues have been addressed. No open security concerns remain on this pull request.

Security review

No open security issues remain on this pull request.

Fixed/addressed: 1 · PR risk: 0/10

[trunk-io]

   

View Full Report ↗︎ ⋅ Docs

[stamphog]

Two independent reviewers (parameterai and veria-ai bots) both identify the same concrete, verified gap: defangMarkdownLinks/flatten_markdown only strip inline [text](url) links, not CommonMark reference-style links ([text][ref] + [ref]: url), which remark-gfm still renders as clickable — so attacker-influenced recording text can produce a live phishing link exactly where this PR claims to close that exposure. The diff confirms the regexes only match inline syntax, and the discussion thread explicitly states the issue remains unaddressed.

• Author wrote 0% of the modified lines and has 13 merged PRs in these paths (familiarity MODERATE).
• Reference-style markdown links ([text][ref] / [ref]: url) bypass both defangMarkdownLinks (frontend/utils/markdown.ts) and flatten_markdown (backend/observation_formatting.py), letting untrusted scanner-derived text render as a clickable phishing link in the Model reasoning card — flagged independently by two reviewer bots and still unresolved.
• Author is cross-team (not on @PostHog/team-replay or @PostHog/platform-ux) with only MODERATE familiarity, so there is no owning-team or STRONG-familiarity assurance path available either.

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	420L, 14F substantive, 597L/17F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1d-complex (597L, 17F, two-areas, feat)
stamphog 2.0.0b4		.stamphog/policy.yml @ 5feec2c · reviewed head 5feec2c

[posthog]

✅ Visual changes approved by hayne — baseline updated in 6f25d21.

View this run in PostHog

6 new.

[fasyy612]

/trunk merge

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-09-08 18:41 UTC	Run
prod-us	✅ Deployed	2026-09-08 19:04 UTC	Run
prod-eu	✅ Deployed	2026-09-08 19:06 UTC	Run