fix: stop the PostHog OAuth sign-in redirect loop

[posthog]

Changes

Problem

• Everyone who picks "Sign in with PostHog" on posthog.com hits a redirect loop on /connect/posthog/redirect and lands back on the marketing home page, not signed in. The defect shipped on 2026-07-22 with the flow (464d7be).
• The landing page cleared the access token with a raw window.history.replaceState. The Gatsby router and the desktop window record never learn about it, so the stored location.search keeps the token.
• Any window navigation then rebuilds the URL from path + stored search, puts the token back, and remounts the page. On remount the replay guard resets and re-runs the exchange with a token the server has already consumed.
• The remount also throws away component state, so the disambiguation modal loses its pending token and mode — which is why "I already have an account" appears to do nothing.

Fix

• Strip the token through the router (navigate(pathname, { replace: true })), which updates the stored window record too, so no later navigation can restore it. This ends the loop.
• Keep the in-flight sign-in in sessionStorage — the pending disambiguation token and the chosen "create vs link" screen — so a remount restores the flow instead of replaying a consumed token.
• Return the user to where they started after a completed sign-in or link, instead of navigate('/') to the home page.

Why

The PostHog sign-in path was broken end to end: users who chose the PostHog button could not complete sign-in and were dropped on the home page, with email and password the only workaround.

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

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Created with PostHog Desktop from this inbox report.

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Aug 13, 2026 01:32PM

[github-actions]

Bundle report

Total JS (gzip)

7.52 MiB (+0.6 KiB / +0.0%)

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

Entrypoint	Eager size	Budget	Modules
✅ app	16.86 MiB (+6.4 KiB / +0.0%)	report-only	2019

Largest modules in the app closure

Module	Size
./src/data/mcp-tools.json	994.5 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	745.9 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
./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	354.5 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	296.6 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/SearchUI/index.tsx + 87 modules	273.0 KiB
./node_modules/.pnpm/@posthog+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/magnifying-glass.mjs	254.7 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

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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).