docs(flags): document client-side access to remote config flags

[gantoine]

Changes

Fixes a gap on the remote config docs page that led readers to conclude remote config can't be used from webapps or CLIs, since the page only documented server-side fetching with the feature flags secure API key (community question, Zendesk #62493).

• Adds a "Using remote config in client-side apps" section: non-encrypted remote config flags are served through the public /flags endpoint with the project API key (phc_...), read via getFeatureFlagPayload — works for webapps, CLIs, and anything else that can call /flags.
• Clarifies the feature flags secure API key is only required for server-side local evaluation and encrypted payloads, not remote config in general.
• Adds an "Encrypted payloads" section: encrypted payloads are excluded from /flags and are server-side only — personal API keys get decrypted payloads, the secure key gets them redacted.

Verified against the rust/feature-flags service behavior in the posthog monorepo.

🤖 Generated with Claude Code

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Jul 22, 2026 05:09PM

[github-actions]

Vale prose linter → found 0 errors, 11 warnings, 0 suggestions in your markdown

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contents/docs/feature-flags/remote-config.mdx — 0 errors, 11 warnings, 0 suggestions

Line	Severity	Message	Rule
19:135	warning	Use 'project token' instead of 'project API key'. The project token (phc_) is not an API key.	PostHogBase.ProjectToken
19:290	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
25:86	warning	Use 'project token' instead of 'project API key'. The project token (phc_) is not an API key.	PostHogBase.ProjectToken
31:58	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
31:246	warning	Use 'project token' instead of 'project API key'. The project token (phc_) is not an API key.	PostHogBase.ProjectToken
35:23	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
41:42	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
47:56	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
81:173	warning	Avoid trivializing words. 'simply' can sound dismissive to the reader.	PostHogDocs.Trivializers
85:204	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
89:4	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames

[github-actions]

Bundle report

Total JS (gzip)

6.75 MiB (+0.2 KiB / +0.0%)

Eager graph (modules shipped in each entrypoint's initial chunks)

Entrypoint	Eager size	Budget	Modules
✅ app	16.22 MiB (+2.2 KiB / +0.0%)	report-only	1981

Largest modules in the app closure

Module	Size
./src/data/mcp-tools.json	890.8 KiB
css ./node_modules/.pnpm/css-loader@5.2.7_webpack@5.101.3/node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[1]!./node_modules/.pnpm/postcss-loader@4.3.0_postcss@8.5.6_webpack@5.101.3/node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[2]!./src/styles/global.css	747.2 KiB
./src/components/Stickers/Stickers.tsx	696.4 KiB
./node_modules/.pnpm/@radix-ui+react-icons@1.3.2_react@18.3.1/node_modules/@radix-ui/react-icons/dist/react-icons.esm.js	481.4 KiB
./node_modules/.pnpm/rehype-raw@7.0.0/node_modules/rehype-raw/lib/index.js + 29 modules	395.1 KiB
./node_modules/.pnpm/@posthog+icons@0.36.6_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.cjs.js	364.8 KiB
./src/hooks/useCustomers.tsx + 54 modules	355.1 KiB
./node_modules/.pnpm/@posthog+icons@0.36.6_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js	354.8 KiB
./node_modules/.pnpm/react-markdown@8.0.7_@types+react@16.14.66_react@18.3.1/node_modules/react-markdown/lib/react-markdown.js + 88 modules	351.4 KiB
./node_modules/.pnpm/cloudinary-core@2.14.0_lodash@4.17.21/node_modules/cloudinary-core/cloudinary-core.js	281.9 KiB
./src/components/ProductComparisonTable/index.tsx + 120 modules	278.6 KiB
./src/components/SearchUI/index.tsx + 87 modules	272.1 KiB
./node_modules/.pnpm/framer-motion@10.18.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/framer-motion/dist/es/render/dom/motion.mjs + 109 modules	253.9 KiB
./node_modules/.pnpm/d3@7.9.0/node_modules/d3/src/index.js + 208 modules	247.4 KiB
./src/components/Pricing/PricingSlider/Slider.tsx + 87 modules	239.9 KiB

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Eager-graph budgets are report-only until a baseline is established. Sizes are gzip of public/**/*.js; eager size is webpack module source bytes for the modules actually shipped in the entrypoint's initial chunks (post-tree-shake).