feat(tracing): split viewer UI state out of tracingSceneLogic

[jonmcwest]

Problem

tracingSceneLogic mixes two concerns: URL sync for /tracing (a scene concern) and viewer UI state — the trace drawer, the compare-flame modal, and the "filter changed → re-run query" wiring (viewer concerns). Worse, the re-query on filter change was a side effect of the scene's actionToUrl (buildUrl() called runQuery()), so an embedded viewer with no URL sync would never refresh its data.

This is step two of the embeddable TracingViewer work, following #68678 (keyed logics, merged). It adopts the boundary the logs product already established: URL sync stays in the scene logic (logsSceneLogic owns all urlToAction/actionToUrl), viewer state lives in a keyed, URL-free logic (logsViewerLogic), and the keyed data logic owns query re-runs (mirroring handleQueryChange).

Changes

• New keyed tracingViewerLogic: the trace drawer (selected trace/span/ts, open/close, the prefetch-or-fetch-by-id decision) and compare-flame modal state, moved verbatim from the scene logic. Zero router imports.
• tracingDataLogic now listens to its connected filter actions and dispatches handleFilterChange (analytics capture + runQuery). Comparison-window drags (updateComparisonWindows) refetch the aggregation here; the compare-flame refetch (viewer state) lives in the viewer logic. New autoLoad prop (default off) lets embeds run their first query on mount — the scene's first query still comes from urlToAction.
• tracingSceneLogic keeps ALL URL sync (including the new comparison URL params from feat(tracing): rework compare mode around explicit baseline presets #69677), breadcrumbs, and the scene tabs. Its buildUrl is now a pure URL write (syncUrlAndRunQuery renamed to syncUrl), and it listens to the keyed logics' actions (handleFilterChange, setFilters) to write the URL. The deterministic ordering the Operations full-range fetch relies on is preserved: the data logic mounts before the scene logic, so its windowed fetchAggregation still fires before the scene's full-range one.
• The scene re-exports the viewer logic's values/actions via connect, so TracingScene.tsx changes are limited to attaching/binding the new logic.

/tracing behavior is unchanged: same URL params, same deep links, same query cadence.

How did you test this code?

Automated tests, all green locally:

• New in tracingDataLogic.test.ts: a keyed instance re-runs its query on a filter change with no URL involvement (the embed-critical wiring this PR exists to create — before it, re-query only happened via the scene's URL write), and autoLoad runs the first query on mount (an embed's only entry point; dropping it leaves embeds permanently empty).
• New tracingViewerLogic.test.ts: the moved (previously untested) drawer prefetch decision — cold link fetches by id, a partial prefetch batch doesn't, a full batch refetches (truncation).
• Updated 4 existing tests whose call-count expectations changed because filter changes now auto-re-query inside the keyed stack — they now assert the stronger behavior (the scope change itself triggers the refetch) deterministically via expectLogic.
• All 16 tracing frontend suites pass (151 tests).
• Typecheck: 0 errors in the 6 changed files. The local full run reports pre-existing errors in unrelated products (subscriptions, brand stories) that exist independently of this diff — CI's typegen-then-typecheck pipeline is authoritative there.

Not manually tested in a browser.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

Docs update

No user-facing behavior change; internal refactor.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Authored by Claude (PostHog Code session) with Jon directing. Skills invoked: /writing-kea-logics, /writing-tests. Jon set the key constraint: follow the logs boundary, where URL sync stays in the scene logic — studying logsSceneLogic/logsViewerLogic settled the design. Originally built against the pre-merge #68678 branch; after that squash-merged and the compare-mode rework (#69677) landed, the commit was cherry-picked onto master and ported to the new comparison API (setCompareMode/setOverlayWindows → setComparison/updateComparisonWindows, fetchAggregation({ fullRange })), preserving #69677's windowed-vs-full-range fetch ordering. Notable find while porting: the query re-run hidden inside buildUrl() — the reason embeds could never refresh. Three oxlint expect-expect warnings on the new tests are false positives (assertions inside try blocks), consistent with the pattern merged in #68678.

---

Created with PostHog Code

[github-actions]

🤖 CI report

⚠️ Bundle size — 🔺 +11.7 KiB (+0.0%)

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

Total: 64.35 MiB · 🔺 +11.7 KiB (+0.0%)

File	Size	Δ vs base
posthog-app/src/scenes/feature-flags/FeatureFlagForm.js	22.3 KiB	🔺 +22.3 KiB (new)
posthog-app/src/scenes/feature-flags/FeatureFlag.js	94.4 KiB	🟢 -21.2 KiB (-18.3%)
posthog-app/_parent/products/feature_flags/frontend/staff/FeatureFlagsStaffToolsScene.js	15.3 KiB	🔺 +4.7 KiB (+44.5%)
render-query/src/render-query/render-query.js	21.21 MiB	🔺 +1.5 KiB (+0.0%)
posthog-app/_parent/products/tracing/frontend/TracingScene.js	91.1 KiB	🔺 +1.2 KiB (+1.3%)
posthog-app/src/scenes/cohorts/Cohort.js	35.4 KiB	🔺 +1005 B (+2.9%)

_{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	1.21 MiB · 22 files	🔺 +7 B (+0.0%)	███░░░░░░░ 28.1% of 4.29 MiB
authenticated shell (every logged-in page) src/scenes/AuthenticatedShell.tsx	8.11 MiB · 2,973 files	🔺 +8.1 KiB (+0.1%)	█████████░ 87.7% of 9.25 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/scenes/AuthenticatedShell.tsx
🟢 src/lib/components/ActivityLog/describers 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
912 B	../node_modules/.pnpm/ieee754@1.2.1/node_modules/ieee754/index.js
789 B	src/scenes/ChunkLoadErrorBoundary.tsx
668 B	src/index.tsx

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

Size	File
278.6 KiB	../node_modules/.pnpm/posthog-js@1.399.5/node_modules/posthog-js/dist/rrweb.js
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
234.9 KiB	src/taxonomy/core-filter-definitions-by-group.json
222.1 KiB	../node_modules/.pnpm/posthog-js@1.399.5/node_modules/posthog-js/dist/module.js
164.0 KiB	src/queries/validators.js
154.3 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
105.9 KiB	src/lib/api.ts
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

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

⚠️ Dist folder size — 🔺 +2.61 MiB (+0.2%)

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

Total: 1281.30 MiB · 🔺 +2.61 MiB (+0.2%)

[trunk-io]

     

View Full Report ↗︎ ⋅ Docs

[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 a533988 · box box-13a317ad2d05 · ready in 701s (push → usable) · build log · rebuilds on every push, torn down on close}

[greptile-apps]

_{Reviews (1): Last reviewed commit: "Merge branch 'master' into posthog-code/..." | Re-trigger Greptile}

[stamphog]

Frontend kea-logic refactor with no risky-territory footprint (no auth, billing, migrations, API contracts, deps, or CI); the sole substantive reviewer concern (Greptile's full-range aggregate regression) was fixed and covered by a new regression test, with Greptile thumbs-upping the fix.

• Author wrote 52% of the modified lines and has 44 merged PRs in these paths (familiarity MODERATE).
• 👍 on the PR from greptile-apps[bot], hex-security-app[bot].

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	382L, 4F substantive, 535L/7F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1d-complex (535L, 7F, single-area, feat)
stamphog 2.0.0b3		.stamphog/policy.yml @ 100f1cf · reviewed head a533988

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-07-14 14:47 UTC	Run
prod-us	✅ Deployed	2026-07-14 14:58 UTC	Run
prod-eu	✅ Deployed	2026-07-14 14:59 UTC	Run