docs(data-warehouse): add an AppSignal source page

[posthog]

Changes

AppSignal is live as a data warehouse source, and the connector's own docs link points at /docs/cdp/sources/appsignal. That page did not exist, so anyone who connected AppSignal had no setup or schema guidance.

This adds the page, in the same shape as the other engineering and monitoring source pages (AppDynamics, New Relic, Gainsight CS):

• The two values a user supplies: the personal API token, and the app ID from the app's AppSignal URL.
• Which tables sync incrementally, which are append-only, which merge, and which are full refresh only, with the reason in each case.
• The first-sync lookback bounds for metrics and traces, and the per-run trace limit for trace_spans.
• Troubleshooting for the errors the connector reports by name (401, 403, 404, and app not found), plus empty log_lines and missing metrics.

The alpha callout, the configuration form, and the table list come from the shared snippets and the sourceId frontmatter, so the fields and the table descriptions stay in sync with the connector.

Why: the connector shipped without its public page, which left users to guess at the credentials and the sync behavior. The content comes from the source's own configuration and its implementation, not from assumptions.

Checks

• Content-only change: one new file under contents/, no navigation change, so no PR tour or reviewer's guide. No page moved, so no redirect is needed.
• Loaded /docs/cdp/sources/appsignal on the dev server in light and dark mode, at a narrow and a wide window. The title, the configuration table, and all table rows render. The console errors are the same set two existing source pages produce (gainsight-cs, appdynamics), so the page adds none.
• Spacing follows the rules in scripts/fix-mdx.js. .md files are outside the pnpm format globs. Prose checked by hand against the local Vale rules; the vale binary is not installed in this environment.

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 (no page moved)

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Created with PostHog Desktop from an inbox report

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Sep 14, 2026 09:39PM

Changed pages

Page	Source
Linking AppSignal as a source	contents/docs/cdp/sources/appsignal.md

[github-actions]

Vale prose linter → found 0 errors, 3 warnings, 0 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/cdp/sources/appsignal.md — 0 errors, 3 warnings, 0 suggestions

Line	Severity	Message	Rule
9:11	warning	'Appsignal' is a possible misspelling.	PostHogBase.Spelling
19:131	warning	Use the Oxford comma before 'and' or 'or' in a list of three or more items.	PostHogBase.OxfordComma
73:85	warning	Capitalize 'Logs' for PostHog's product. Use 'logs' for the general industry concept.	PostHogBase.ProductNames

[github-actions]

Bundle report

Total JS (gzip)

8.78 MiB (no change)

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

Entrypoint	Eager size	Budget	Modules
✅ app	18.51 MiB (no change)	report-only	2062

Largest modules in the app closure

Module	Size
./src/data/mcp-tools.json	1137.8 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	773.5 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/@posthog+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/x-ray.mjs	480.8 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+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/im-the-driver.mjs	385.7 KiB
./src/hooks/useCustomers.tsx + 55 modules	370.0 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
./src/components/ProductComparisonTable/index.tsx + 126 modules	305.7 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/@posthog+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/doll-house.mjs	281.7 KiB
./node_modules/.pnpm/@posthog+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/director.mjs	275.6 KiB
./src/components/SearchUI/index.tsx + 87 modules	273.7 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).