docs: update Ruby SDK documentation

[marandaneto]

Changes

Problem

follow up PostHog/posthog-ruby#149

Ruby and Rails docs were missing newer SDK configuration options, request context behavior, and the evaluate_flags migration path.

Changes

• Expanded Ruby SDK configuration docs with client options, singleton guidance, before_send, flushing/shutdown, and test helpers.
• Updated feature flag docs to prefer evaluate_flags, document local-only evaluation, GeoIP disabling, remote config payloads, and legacy API replacements.
• Refreshed Rails docs with request context, tracing headers, error capture details, ActiveJob user association, and updated configuration tables.

No screenshots or screen recordings — documentation-only change.

Checklist

• I've read the docs and/or content style guides.
• Words are spelled using American English
• Use relative URLs for internal links
• I've checked the pages added or changed in the Vercel preview build
• If I moved a page, I added a redirect in vercel.json

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	May 20, 2026 01:12PM

[github-actions]

Vale prose linter → found 1 errors, 43 warnings, 8 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/integrate/feature-flags-code/_snippets/feature-flags-code-ruby.mdx — 0 errors, 4 warnings, 2 suggestions

Line	Severity	Message	Rule
1:34	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
5:42	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
7:14	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
19:19	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
100:57	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
135:9	warning	'deduplicates' is a possible misspelling.	PostHogBase.Spelling

contents/docs/libraries/ruby-on-rails.mdx — 0 errors, 20 warnings, 4 suggestions

Line	Severity	Message	Rule
8:18	warning	Avoid trivializing words. 'easy to' can sound dismissive to the reader.	PostHogDocs.Trivializers
8:147	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
10:81	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
25:23	warning	'Gemfile' is a possible misspelling.	PostHogBase.Spelling
44:18	warning	'initializer' is a possible misspelling.	PostHogBase.Spelling
46:49	warning	'initializer' is a possible misspelling.	PostHogBase.Spelling
58:15	warning	'initializer' is a possible misspelling.	PostHogBase.Spelling
92:5	warning	'Feature flags' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
92:5	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames
117:124	warning	'hardcoding' is a possible misspelling.	PostHogBase.Spelling
117:198	warning	'initializer' is a possible misspelling.	PostHogBase.Spelling
174:4	warning	'Error tracking' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
174:4	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'Error tracking' for the general industry concept.	PostHogBase.ProductNames
176:32	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
176:74	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
205:18	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
280:32	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
294:40	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
362:28	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
448:83	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
470:15	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
473:5	warning	'Feature flags not working' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
473:5	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames
479:107	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames

contents/docs/libraries/ruby/index.mdx — 1 errors, 19 warnings, 2 suggestions

Line	Severity	Message	Rule
6:18	warning	Use 'GitHub' instead of 'github'.	Vale.Terms
6:37	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
22:48	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
22:231	warning	Capitalize 'Logs' for PostHog's product. Use 'logs' for the general industry concept.	PostHogBase.ProductNames
54:134	warning	'Resque' is a possible misspelling.	PostHogBase.Spelling
118:28	suggestion	Address the reader directly. Use 'you' instead of 'The user'.	PostHogDocs.DirectAddress
118:163	warning	'personless' is a possible misspelling.	PostHogBase.Spelling
172:4	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames
172:4	warning	'Feature flags' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
202:17	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
217:6	warning	'Evaluating feature flags locally in a Puma server' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
217:17	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
261:8	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
261:55	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
261:128	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
272:28	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
272:54	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
314:156	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
318:6	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
318:169	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
344:49	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
362:14	warning	Capitalize 'Logs' for PostHog's product. Use 'logs' for the general industry concept.	PostHogBase.ProductNames