feat: add config builder

[sarahxsanders]

reviving this one from the depths. re: https://posthog.slack.com/archives/C043VJ93L3B/p1772223020503949

adds a configurable code snippet builder

demo on JS Web SDK config page:

CleanShot.2026-02-27.at.16.59.21.mp4

[daniloc]

this is badass and clearly the right thing to do imo.

My big question: is there anything we can do to trip an alarm if/when the configuration values drift out of date?

or even better, would it be possible to always derive them from the source code?

(edit: to be clear I am asking this in the abstract, not with any concrete knowledge of how often this happens. Maybe it's not a big deal! just thinking of the case where we have some new config item and it doesn't get added, and how we'd guard against that)

[sarahxsanders]

this is badass and clearly the right thing to do imo.

My big question: is there anything we can do to trip an alarm if/when the configuration values drift out of date?

or even better, would it be possible to always derive them from the source code?

(edit: to be clear I am asking this in the abstract, not with any concrete knowledge of how often this happens. Maybe it's not a big deal! just thinking of the case where we have some new config item and it doesn't get added, and how we'd guard against that)

this actually crossed my mind this morning when I was re-looking at the PR. maintenance is definitely an issue. derive from source code would be SICK... I will dig into that 🙏🏼

[edwinyjlim]

I prefer the two column layout because it always spotlights the code, but the description text looks cramped on a laptop

instead of having the code block be fixed or sticky, maybe we try increasing the code block's min-height (or the same height as the entire component) and making the config list be scrollable. that way it doesn't eat up the entire vertical scroll

feel free to go a different direction, it's lookin awesome

config-builder-ui.mp4

[edwinyjlim]

or maybe you do single column layout but you fix the code block at the top with sticky scroll

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Mar 02, 2026 10:39PM

[github-actions]

Vale prose linter → found 2 errors, 32 warnings, 1 suggestions in your markdown

Full report → Copy the linter results into an LLM to batch-fix issues.

Linter being weird? Update the rules!

contents/docs/libraries/js/config.mdx — 2 errors, 30 warnings, 1 suggestions

Line	Severity	Message	Rule
20:136	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
42:242	warning	'pageleave' is a possible misspelling.	PostHogBase.Spelling
48:205	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
48:308	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
50:213	warning	Capitalize 'Logs' for PostHog's product. Use 'logs' for the general industry concept.	PostHogBase.ProductNames
52:233	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
53:270	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
54:448	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
54:500	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
54:565	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
60:263	warning	'googlebot' is a possible misspelling.	PostHogBase.Spelling
61:239	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
76:68	warning	'autocapture's' is a possible misspelling.	PostHogBase.Spelling
82:187	warning	'textarea' is a possible misspelling.	PostHogBase.Spelling
87:16	warning	'rageclick' is a possible misspelling.	PostHogBase.Spelling
106:216	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
106:255	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
107:178	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
108:152	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
108:170	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
108:236	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
108:254	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames
108:291	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
109:130	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
111:125	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
111:390	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
113:118	warning	'params' is a possible misspelling.	PostHogBase.Spelling
114:482	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
121:244	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
135:125	warning	'gzip' is a possible misspelling.	PostHogBase.Spelling
136:7	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames
136:50	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
137:63	warning	Capitalize 'Surveys' for PostHog's product. Use 'surveys' for the general industry concept.	PostHogBase.ProductNames

src/components/Docs/ConfigBuilder.README.md — 0 errors, 2 warnings, 0 suggestions

Line	Severity	Message	Rule
45:28	warning	'breakpoint' is a possible misspelling.	PostHogBase.Spelling
46:15	warning	'scrollable' is a possible misspelling.	PostHogBase.Spelling

[edwinyjlim]

aw yeah. wanna try building your use case on top of this branch @willwearing?

[willwearing]

I'm not seeing the 'Navigate to' affordance and think it would be useful/look better

Context on Loom here: https://www.loom.com/share/e087fb6db15d4a51a68a258b4789d561