feat(experiments): track health findings and every launch path by mp-hog · Pull Request #110279 · PostHog/posthog

mp-hog · 2026-10-01T18:54:06Z

Problem

The Experiments team cannot count how often people see an experiment's warnings, open them, or use the fix a warning offers.
Three of the warnings send no event, and no warning's action sends one.
experiment launched misses two of the three ways to launch: a create call with a start date, and an update that starts a draft.

Changes

The experiment page sends experiment health finding shown for each warning on screen, once per experiment load.
It sends experiment health finding opened when a person opens the Exposures panel on a warning, or follows the bias banner's documentation link.
It sends experiment health finding acted on when a person uses the action a warning offers.
experiment results refresh completed gains the exposure state, because the exposure warnings render on one tab only.
experiment launched fires on all three launch paths, with launch_path and flag_age_seconds.
A failed launch report no longer fails a launch that is already saved.
The experiments list sends experiments list viewed, and experiment viewed gains experiment_id and experiment_status.
The finding events carry ids and codes only, with no experiment name and no flag key.
Nothing looks different in the UI, so there is no screenshot. The two older warning events keep firing.

Note

Counts of experiment launched step up when this deploys. Filter on launch_path = launch_endpoint for the old series.

How did you test this code?

experimentLogic.test.ts: one event per finding per load, "shown" before "opened", and the exposure state on the refresh event.
healthFindingReporting.test.tsx: the rendered warnings send "shown", and a click on each action, link and panel sends its event.
Experiment.test.tsx: a running experiment without metrics reports its warnings and both add-metric clicks, and a draft reports none.
experimentsLogic.test.ts: the list reports a view on its own tab only, with the filters of the request that answered.
test_experiment_service.py: each launch path reports once with its flag age, and a failing report leaves the launch saved.
Not checked: the events in a browser against a running stack.

Test rationale: The regressions are a warning, an action or a launch path that stops reporting, and a finding that reports twice in one load. The closest tests, test_lifecycle_action_emits_exact_event_name and the experimentWarning block, assert an event name or a selector only.

Release status

No feature flag controls this change

Automatic notifications

Publish to changelog?

Docs update

None. The events are internal telemetry.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Agent: Claude Code, Opus 5.5 (claude-opus-5-5)

Skills invoked: /placing-product-frontend-code, /writing-ui-components, /writing-kea-logics, /writing-tests, /writing-code-comments, /simplify, /reviewing-with-coderabbit, /writing-pr-descriptions.
CodeRabbit local pass: skipped, the CLI was signed out.
Bot review, fixed: the list event reads the status filter of the request that answered (CodeRabbit). Zero exposures reports only while its warning is visible, and click tests cover the warning actions (Greptile).
Bot review, not changed: binding the exposure state to the refresh that loaded it (CodeRabbit). The event reports the state the page holds when the refresh completes.
A second agent session reviewed the diff. The later commits build its findings, except a move of the reporting into its own logic.
Public artifact: the diff carries no session material, and the test data is invented.

🤖 Generated with Claude Code

The experiment page reports each warning it shows, once per experiment load, and each use of a warning's action, under two new events. `experiment launched` now also fires when a create call carries a start date and when an update sets the start date of a draft, with `launch_path` and `flag_age_days`. The experiments list reports `experiments list viewed`, and `experiment viewed` gains `experiment_id` and `experiment_status`. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

trunk-io · 2026-10-01T18:54:10Z

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github-actions · 2026-10-01T18:54:27Z

🤖 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) — 5 functions above the limit (max 33)

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
`Exposures`	`frontend/src/scenes/experiments/ExperimentView/Exposures.tsx:128`	33	10
`refreshExperimentResults`	`frontend/src/scenes/experiments/experimentLogic.tsx:2481`	27	10
`moveMetricsBetweenSections`	`frontend/src/scenes/experiments/experimentLogic.tsx:3300`	23	10
`<anonymous>`	`frontend/src/scenes/experiments/experimentLogic.tsx:3939`	15	10
`setFunnelsMetric`	`frontend/src/scenes/experiments/experimentLogic.tsx:1726`	13	10

✅ Duplication (Python) — clean

New Python code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

✅ Duplication (TypeScript) — clean

New TypeScript code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

⚠️

Comment density — 5% of added code lines are comments (42 of 884)

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
`products/experiments/frontend/health/experimentHealthFindingEvents.ts`	18	117
`frontend/src/scenes/experiments/experimentLogic.tsx`	7	69
`products/experiments/frontend/health/useHealthFindingReporting.ts`	5	49
`frontend/src/scenes/experiments/ExperimentView/Exposures.tsx`	3	29
`products/experiments/backend/experiment_service.py`	2	42
`products/experiments/frontend/scenes/experimentsLogic.ts`	2	36
`frontend/src/scenes/experiments/Experiment.test.tsx`	1	19
`frontend/src/scenes/experiments/ExperimentView/ExperimentView.tsx`	1	11

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

⚠️

Bundle size — 🔺 +2.9 KiB (+0.0%)

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

Total: 69.79 MiB · 🔺 +2.9 KiB (+0.0%)

File	Size	Δ vs base
`render-query/src/render-query/render-query.js`	18.77 MiB	🔺 +2.3 KiB (+0.0%)

_{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`	1.63 MiB · 22 files	no change	`█████████░` 88.7% of 1.84 MiB
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authenticated shell (every logged-in page) `src/scenes/AuthenticatedShell.tsx`	7.59 MiB · 2,410 files	🔺 +892 B (+0.0%)	`█████████░` 91.0% of 8.34 MiB
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🟢 node_modules/monaco-editor/ stays out of src/index.tsx
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🟢 [object Object] stays out of src/index.tsx
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🟢 src/layout/navigation-3000/navigationLogic.tsx stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
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🟢 src/lib/lemon-ui/LemonMarkdown/ stays out of src/index.tsx + src/scenes/App.tsx + src/scenes/bootApp.ts
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🟢 src/taxonomy/core-filter-definitions-by-group.json 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
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_{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 2.20 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	2.20 MiB · 19 files	no change	`████░░░░░░` 38.4% of 5.72 MiB
Deferred (lazy)	2.11 MiB · 44 files	no change	n/a — loads on demand
Loader `dist/toolbar.js`	1.2 KiB	no change	`█░░░░░░░░░` 6.0% of 19.5 KiB

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✅ Dist folder size — 🔺 +95.8 KiB (+0.0%)

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

Total: 960.52 MiB · 🔺 +95.8 KiB (+0.0%)

✅ Playwright — all passed

All tests passed.

View test results →

coderabbitai · 2026-10-01T18:59:07Z

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📒 Files selected for processing (2)

products/experiments/backend/experiment_service.py
products/experiments/backend/test/test_experiment_service.py

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products/experiments/backend/experiment_service.py

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📝 Walkthrough

Walkthrough

The change adds frontend analytics for experiment health findings, actions, exposure properties, and list views. Experiment-view events now include the experiment ID and status. The backend reports launch paths, launch dates, and feature-flag age for launches through the endpoint, creation with a start date, and draft updates that set a start date. Tests cover these reporting paths and event properties.

Priority: ➖ Normal

Merge Risk: 🔵 Low · up to 4a4d0

Some experiment analytics can still associate a list response with the wrong filter or a refresh with the wrong exposure snapshot. These bounded reporting risks remain for the owner to address or accept before merging.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 4a4d0

The visible changes center on analytics, with deliberately limited health-event payloads and reporting failures isolated from saved launches. No introduced security issue was established. Launch authorization, concurrent transition behavior, and production telemetry access remain incompletely verified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

inferred — The visible expansion concerns experiment activity and lifecycle metadata reaching analytics through additional UI actions and launch producers. The evidence does not establish maximum tenant, data-store, or environment exposure because production telemetry isolation and access policies are unavailable.

Trust Boundaries and Controls

inferred — Lifecycle reporting previously required a request and now proceeds when either a request or event source is present. This broadens analytics reporting contexts, not demonstrably business-operation authority. The complete metadata, downstream identity treatment, and authorization checks for those contexts could not be verified.

Resilience and Maintainability Implications

inferred — The described endpoint sequence writes launch state before reporting, and the new exception handling contains telemetry failure. This supports separation of analytics availability from launch success, without establishing commit completion or exactly-once reporting across retries and crashes.

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Description check	✅ Passed	The description includes the required Problem, Changes, testing, test rationale, release status, notifications, docs, and agent context sections. It explains the telemetry changes, test coverage, omit…

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products/experiments/frontend/scenes/experimentsLogic.ts-620-620 (1)

620-620: 🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Report the status filter used by the completed request.

If a user changes the status filter while a request is pending, that response can finish during the 300 ms debounce before the next loadExperiments starts. The loader breakpoint does not reject that response yet. This line then reports the previous result count with the new values.filters.status, which mislabels the event.

Snapshot the filters before api.get, return that snapshot with the response, and read its status here.

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📒 Files selected for processing (14)

frontend/src/lib/utils/eventUsageLogic.ts
frontend/src/scenes/experiments/Experiment.test.tsx
frontend/src/scenes/experiments/ExperimentView/ExperimentView.tsx
frontend/src/scenes/experiments/ExperimentView/ExperimentWarningBanners.tsx
frontend/src/scenes/experiments/ExperimentView/Exposures.tsx
frontend/src/scenes/experiments/ExperimentView/MultiVariantBiasWarning.tsx
frontend/src/scenes/experiments/experimentLogic.test.ts
frontend/src/scenes/experiments/experimentLogic.tsx
products/experiments/backend/experiment_service.py
products/experiments/backend/test/test_experiment_service.py
products/experiments/frontend/health/experimentHealthFindingEvents.ts
products/experiments/frontend/health/useHealthFindingReporting.ts
products/experiments/frontend/scenes/experimentsLogic.test.ts
products/experiments/frontend/scenes/experimentsLogic.ts

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greptile-apps · 2026-10-01T19:01:11Z

[Medium risk] Adds event tracking for experiment health findings and user actions.

The PR appears safe to merge; no outstanding review finding was identified.

_{Reviews (2) · Last reviewed commit: "fix(experiments): report the flag age at..."}

trunk-io · 2026-10-01T19:23:56Z

Failed Test	Failure Summary	Logs
`Scenes/Code review Default play-test`	The test failed because a logic component was not mounted when accessed, and there were unhandled network requests intercepted by the mock service...	Logs ↗︎
`Scenes-App/Notebooks/Nodes/Customer Journey AllStepsCompleted smoke-test`	The test timed out while waiting for an element with the class '.react-flow__node' to become visible.	Logs ↗︎

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The zero-exposure finding fired from the collapsed Exposures panel, where "No exposures yet" is not rendered. It now fires while the open panel shows that state. `experiments list viewed` reads the status filter of the request that answered, so a filter change during the request does not relabel it. A click test covers the four warning actions. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

- `experiment health finding opened`: a reader opens the Exposures panel on a sample ratio mismatch or on zero exposures, or follows the documentation link of the bias banner. - `experiment health finding acted on` for "Add primary metric" and "Add secondary metric" under "No metrics defined". The code is `no_metric`, because the warning shows only for an experiment with no metric of either kind. - `experiment results refresh completed` carries `exposures_total`, `has_srm` and `has_bias_risk`. The exposure warnings render on one tab only, so this gives the exposure state for every load of a launched experiment. - `experiment launched` carries `flag_age_seconds`, and a failed launch report no longer fails a launch that is already saved. - `experiments list viewed` carries `page`, `has_search` and `archived`. - The tests assert the events that are sent, and cover the sample ratio emitter and a flag older than a day. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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frontend/src/scenes/experiments/experimentLogic.tsx-2583-2583 (1)

2583-2583: 🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Bind exposure health properties to the refresh that produced them.

In the legacy refresh path, exposure and metric requests run concurrently. Refresh A can finish exposure loading while it still waits for metrics. If refresh B then updates values.exposures, refresh A emits B's exposure properties with A's refresh_id and trigger. Criteria and date changes can start overlapping refreshes.

Store the exposure response in a refresh-local variable and pass it to exposureHealthEventProperties. Add a regression test with overlapping refreshes and different exposure responses.

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📒 Files selected for processing (18)

frontend/src/lib/utils/eventUsageLogic.test.ts
frontend/src/lib/utils/eventUsageLogic.ts
frontend/src/scenes/experiments/Experiment.test.tsx
frontend/src/scenes/experiments/ExperimentForm/MetricsPanel/EmptyMetricsPanel.tsx
frontend/src/scenes/experiments/ExperimentView/ExperimentView.tsx
frontend/src/scenes/experiments/ExperimentView/ExperimentWarningBanners.tsx
frontend/src/scenes/experiments/ExperimentView/Exposures.tsx
frontend/src/scenes/experiments/ExperimentView/MultiVariantBiasWarning.tsx
frontend/src/scenes/experiments/ExperimentView/healthFindingReporting.test.tsx
frontend/src/scenes/experiments/experimentLogic.test.ts
frontend/src/scenes/experiments/experimentLogic.tsx
products/experiments/backend/experiment_service.py
products/experiments/backend/test/test_experiment_service.py
products/experiments/frontend/health/experimentHealthFindingEvents.ts
products/experiments/frontend/health/exposureHealth.ts
products/experiments/frontend/health/useHealthFindingReporting.ts
products/experiments/frontend/scenes/experimentsLogic.test.ts
products/experiments/frontend/scenes/experimentsLogic.ts

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`experiment results refresh completed` carries `exposures_multiple`, the count of the `$multiple` variant in the exposure answer. No other place records it: the stored metric results drop that variant. The property is empty under "first seen" handling. The exposure query then gives each person their first variant and counts no `$multiple`. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

`experiment launched` carried `flag_age_days` next to `flag_age_seconds`. Nothing reads the days value. The seconds give the same fact, and they tell a flag made by the launching request from one made hours earlier. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

parameterai · 2026-10-02T16:00:18Z

Risk: No findings

This change is analytics-only: it adds telemetry events for experiment health findings (shown/opened/acted on), fires experiment launched on all three launch paths, and enriches existing events with exposure state and IDs. No authentication, authorization, query, or input-handling surface is touched, and the new events deliberately carry only ids, codes, and counts — no customer text. No security risk identified.

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github-actions · 2026-10-02T16:00:27Z

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feat(experiments): track health findings and every launch path - #110279

feat(experiments): track health findings and every launch path#110279
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