chore(aio): add Go OpenTelemetry setup to installation docs

[marco-g-pm]

Problem

Go developers land on AI observability docs that show Python and Node only, with no mention of Go anywhere. posthog-go#306 adds a Go OTel bridge, so the docs need to carry the Go path.

For PostHog/posthog-go#306

Changes

• The OpenTelemetry installation page gains a Go tab in every step: go get install, posthogotel.NewSpanProcessor setup, a hand-authored gen_ai.* span around an LLM call, and a context-based session-ID processor.

• Provider and gateway pages (OpenAI, Anthropic, Google, Azure OpenAI, Bedrock, and the 15 OpenAI-compatible pages) gain a Go tab in the install code block. It says no Go wrapper exists yet and links the OpenTelemetry page.

• That tab renders as plain text with a clickable link through a new prose block type in the in-app onboarding CodeBlock renderer. Blocks that do not declare language: 'prose' are untouched. The posthog.com renderer gets the same support in a companion PR.

Note

Merge after posthog-go#306: the page links posthog-go/tree/main/otel/example, which 404s until the bridge lands. Companion PRs: context-mill#373 (wizard variant), wizard-workbench#3675 (fixture), and a posthog.com branch (marco/go-otel-aio-docs) for the site-side renderer and Go library page.

How did you test this code?

• Rendered on a local posthog.com dev site pointed at this branch: the Go tabs show on the OpenTelemetry and provider pages, the prose tab renders as text, and its link navigates to the OpenTelemetry page (screenshots above).
• pnpm --filter=@posthog/frontend typescript:check reports no errors in the touched files.
• Not run: the in-app onboarding scene render. The prose branch there is a four-line conditional beside the existing CodeSnippet call.

Automatic notifications

• Publish to changelog?

Docs update

This PR is the docs-content half; the posthog.com stub pages already import these components.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Written by Claude Code from the Slack thread on posthog-go#306, with the assignee directing scope across the session: a per-page callout box became the condensed Go tab, the tab's code-comment styling became the prose block type, and the install-step Go paragraph and an ADK caveat were cut. Skills invoked: /writing-user-facing-copy, /writing-pr-descriptions. Go samples were checked against the posthog-go PR branch and the openai-go v3 API; the committed content contains only public repo material and placeholders.

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[github-actions]

🤖 CI report

✅ Trunk lane — non-backend lane

This PR is assigned to the non-backend lane. It does not run backend Python tests and may merge in parallel with PRs in other lanes.

⚠️ Bundle size — 🔺 +76.0 KiB (+0.1%)

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

Total: 68.10 MiB · 🔺 +76.0 KiB (+0.1%)

File	Size	Δ vs base
render-query/src/render-query/render-query.js	21.81 MiB	🔺 +12.8 KiB (+0.1%)
posthog-app/src/scenes/real-time-usage/RealTimeUsage.js	12.8 KiB	🔺 +12.8 KiB (new)
posthog-app/src/scenes/onboarding/Onboarding.js	811.0 KiB	🔺 +7.8 KiB (+1.0%)
exporter/src/queries/schema.js	1.20 MiB	🔺 +5.3 KiB (+0.4%)
posthog-app/src/queries/schema.js	1.20 MiB	🔺 +5.3 KiB (+0.4%)
posthog-app/src/scenes/cohorts/Cohorts.js	17.6 KiB	🔺 +4.9 KiB (+39.0%)
posthog-app/src/scenes/dashboard/dashboards/Dashboards.js	29.4 KiB	🔺 +4.3 KiB (+16.9%)
posthog-app/_parent/products/metrics/frontend/MetricsScene.js	73.4 KiB	🔺 +4.2 KiB (+6.1%)
posthog-app/_parent/products/signals/frontend/inbox/InboxScene.js	758.0 KiB	🔺 +3.2 KiB (+0.4%)
posthog-app/src/scenes/surveys/Surveys.js	26.6 KiB	🟢 -2.4 KiB (-8.4%)
exporter/src/exporter/scenes/ExporterNotebookScene.js	3.40 MiB	🔺 +2.2 KiB (+0.1%)
posthog-app/_parent/products/workflows/frontend/WorkflowsScene.js	88.7 KiB	🔺 +2.1 KiB (+2.4%)
exporter/_parent/products/signals/frontend/components/ScoutPicker/CyclotronJobInputScoutPicker.js	1.9 KiB	🔺 +1.9 KiB (new)
posthog-app/_parent/products/signals/frontend/components/ScoutPicker/CyclotronJobInputScoutPicker.js	1.8 KiB	🔺 +1.8 KiB (new)

_{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	1.42 MiB · 22 files	🔺 +21.2 KiB (+1.5%)	███░░░░░░░ 31.5% of 4.51 MiB
authenticated shell (every logged-in page) src/scenes/AuthenticatedShell.tsx	8.84 MiB · 3,248 files	🔺 +6.9 KiB (+0.1%)	█████████░ 91.0% of 9.71 MiB

🟢 node_modules/monaco-editor/ stays out of src/index.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 [object Object] stays out of src/index.tsx
🟢 node_modules/monaco-editor/ stays out of src/scenes/AuthenticatedShell.tsx
🟢 src/lib/components/ActivityLog/describers stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx
🟢 [object Object] stays out of src/scenes/AuthenticatedShell.tsx

Largest files eagerly shipped from src/index.tsx

Size	File
126.8 KiB	../node_modules/.pnpm/react-dom@18.3.1_react@18.3.1/node_modules/react-dom/cjs/react-dom.production.min.js
24.6 KiB	../node_modules/.pnpm/buffer@6.0.3/node_modules/buffer/index.js
6.3 KiB	../node_modules/.pnpm/react@18.3.1/node_modules/react/cjs/react.production.min.js
4.5 KiB	../node_modules/.pnpm/@jspm+core@2.1.0/node_modules/@jspm/core/nodelibs/browser/process.js
3.9 KiB	../node_modules/.pnpm/scheduler@0.23.2/node_modules/scheduler/cjs/scheduler.production.min.js
1.4 KiB	../node_modules/.pnpm/base64-js@1.5.1/node_modules/base64-js/index.js
1.3 KiB	src/RootErrorBoundary.tsx
912 B	../node_modules/.pnpm/ieee754@1.2.1/node_modules/ieee754/index.js
789 B	src/scenes/ChunkLoadErrorBoundary.tsx
762 B	src/index.tsx

Largest files eagerly shipped from src/scenes/AuthenticatedShell.tsx

Size	File
307.0 KiB	../node_modules/.pnpm/posthog-js@1.422.5_@types+react@18.3.27_react@18.3.1/node_modules/posthog-js/dist/rrweb.js
267.7 KiB	../node_modules/.pnpm/@posthog+icons@0.38.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js
263.5 KiB	../node_modules/.pnpm/posthog-js@1.422.5_@types+react@18.3.27_react@18.3.1/node_modules/posthog-js/dist/module.js
253.8 KiB	src/taxonomy/core-filter-definitions-by-group.json
154.2 KiB	../node_modules/.pnpm/re2js@0.4.1/node_modules/re2js/build/index.esm.js
126.8 KiB	../node_modules/.pnpm/react-dom@18.3.1_react@18.3.1/node_modules/react-dom/cjs/react-dom.production.min.js
104.7 KiB	src/lib/api.ts
95.2 KiB	../packages/quill/packages/quill/dist/index.js
93.3 KiB	../node_modules/.pnpm/prosemirror-view@1.40.1/node_modules/prosemirror-view/dist/index.js
90.6 KiB	../node_modules/.pnpm/@tiptap+core@3.20.6_@tiptap+pm@3.20.6/node_modules/@tiptap/core/dist/index.js

_{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 2.26 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	2.26 MiB · 18 files	🔺 +2.6 KiB (+0.1%)	████░░░░░░ 39.5% of 5.72 MiB
Deferred (lazy)	2.11 MiB · 45 files	🔺 +912 B (+0.0%)	n/a — loads on demand
Loader dist/toolbar.js	1.1 KiB	no change	█░░░░░░░░░ 5.8% of 19.5 KiB

Largest eagerly-shipped chunks

Size	File
751.6 KiB	dist/toolbar/toolbar-app-DVROT5MS.css
590.0 KiB	dist/toolbar/chunk-chunk-YNQA4RO7.js
484.7 KiB	dist/toolbar/chunk-chunk-RNKUEDGA.js
134.1 KiB	dist/toolbar/chunk-chunk-57FSVJVI.js
131.8 KiB	dist/toolbar/chunk-chunk-FDH2IBXT.js
71.3 KiB	dist/toolbar/toolbar-app-M2WJJNQC.js
69.0 KiB	dist/toolbar/chunk-chunk-TSAL54PB.js
35.6 KiB	dist/toolbar/chunk-chunk-DLWHLAGH.js
21.0 KiB	dist/toolbar/chunk-chunk-L4QNPKVO.js
6.8 KiB	dist/toolbar/chunk-chunk-DV7IWQNF.js

_{Posted automatically by check-toolbar-size · sizes are toolbar output bytes (shipped, post-tree-shake) from the esbuild metafile}

✅ Dist folder size — 🔺 +5.42 MiB (+0.4%)

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

Total: 1448.18 MiB · 🔺 +5.42 MiB (+0.4%)

✅ Playwright — all passed

All tests passed.

View test results →

ℹ️ Docs preview — preview build triggered

Docs from this PR will be published at posthog.com.

Project	Preview	Updated (UTC)
posthog.com	Open preview	Sep 1, 2026, 4:14 PM

The preview should be ready in about 10 minutes. Open the preview at /handbook/engineering/.

⚠️ complexity-ts — 1 function above 10 (max 18)

Cyclomatic complexity above 10 in changed typescript files. Warn only: worth simplifying when you next touch these functions.

Function	Location	Complexity
CodeBlock	frontend/src/scenes/onboarding/shared/OnboardingDocsContentWrapper.tsx:121	18

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View Full Report ↗︎ ⋅ Docs

[github-actions]

🦔 Hogbox preview · ❌ build failed

The preview didn't come up for commit 7bc85e9. See the build log for the failing step. It'll retry on the next push.

_{Previews are optional and never block merging. A failure here is often a hogland or tailnet hiccup rather than anything in your PR, so the check stays green and this comment is the status.}

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
docs/onboarding/ai-observability/opentelemetry.tsx:170-172
**Existing-provider registration is invalid**

When a Go application already has an initialized `TracerProvider`, `sdktrace.WithSpanProcessor` cannot attach the PostHog processor because it is only a construction-time option. Following this guidance therefore fails to compile or leaves the processor unregistered, so PostHog spans and session IDs are not exported; existing providers require `RegisterSpanProcessor`.

### Issue 2
docs/onboarding/ai-observability/opentelemetry.tsx:242-245
**Failed spans lose AI markers**

When the LLM request returns an error, this branch ends the non-prefixed span before assigning any `gen_ai.*` attributes or error details. The documented PostHog filter consequently drops the span, so failed generations never appear in AI observability.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "chore(aio): add Go OpenTelemetry setup t..." | Re-trigger Greptile}

[carlos-marchal-ph]

Looks good but some details should be amended!