docs: update Rust SDK docs for posthog-rs v0.14 (fire-and-forget capture)

[cat-ph]

Problem

posthog-rs v0.14 (the runtime-independent background transport, posthog-rs#145) made capture and capture_batch non-blocking and infallible — they dropped async and Result and now enqueue onto a background worker. The Rust docs still showed the old API (client.capture(event).await.unwrap()), pinned 0.13.1, described blocking-mode capture as a synchronous network call, and never mentioned flush() / shutdown(). So the examples no longer compile and the guidance is wrong.

Changes

• Drop .await.unwrap() from every capture / capture_batch example (they now return ()). capture_exception is left as-is — it's still async and fallible.
• Bump the install version pin 0.13.1 → 0.14.
• Rewrite the install snippet's blocking-mode note: capture is non-blocking in both modes (a background worker batches and sends), not a synchronous API call.
• Add a Flushing events section to the send-events snippet documenting flush() / shutdown() and the need to flush before process exit so buffered events aren't lost.

Touched: install-rust, send-events-rust, feature-flags-code-rust, experiments/installation/rust, product-analytics/identify, the two product-analytics capture snippets, and getting-started/user-properties-how-to-set.

Testing

• Verified every example against the shipped v0.14 API: capture / capture_batch are pub fn … -> (); flush / shutdown are async on the async client and sync on the blocking client.
• Grepped the whole contents/docs tree to confirm no stale capture(...).await / .unwrap() remain and that capture_exception is untouched.

Opened as a draft.

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Jun 24, 2026 10:39PM

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Vale prose linter → found 0 errors, 5 warnings, 3 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/experiments/installation/rust.mdx — 0 errors, 1 warnings, 1 suggestions

Line	Severity	Message	Rule
2:13	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
78:79	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress

contents/docs/integrate/feature-flags-code/_snippets/feature-flags-code-rust.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
5:41	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
24:19	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
107:57	suggestion	Address the reader directly. Use 'you' instead of 'the user'.	PostHogDocs.DirectAddress
125:9	warning	'deduplicates' is a possible misspelling.	PostHogBase.Spelling

[github-actions]

Bundle report

Total JS (gzip)

6.22 MiB (+0.3 KiB / +0.0%)

Eager graph (static-import closure per entrypoint)

Entrypoint	Eager size	Budget	Modules
✅ app	24.14 MiB (+1.1 KiB / +0.0%)	report-only	5510

Largest modules in the app closure

Module	Size
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	710.3 KiB
./src/components/Stickers/Stickers.tsx	696.4 KiB
./.cache/caches/gatsby-plugin-mdx/mdx-scopes-dir/31a094f140f119e73085d847ae81b99b.js + 2 modules	533.6 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/@codemirror+view@6.38.2/node_modules/@codemirror/view/dist/index.js	458.1 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
./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
./src/hooks/useCustomers.tsx + 54 modules	353.9 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
./node_modules/.pnpm/@codesandbox+sandpack-react@2.20.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@codesandbox/sandpack-react/dist/index.mjs	266.6 KiB
./src/components/ProductComparisonTable/index.tsx + 114 modules	264.0 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.