[ppXD]

Summary

• Issue the HttpOnly session cookie from sign-in, change-password and invitation accept only when the request carries X-CodeSpace-Csrf, which the SPA sends on every request. A client that predates the cookie (an older SPA bundle, an API client, the CLI) cannot clear one, so it never gets one. It keeps the session in the response body, as before. POST /api/auth/session still sets the cookie unconditionally.
• Bring back accountExists on the invitation preview as an [Obsolete] alias of forSignedInAccount for one release. The API is always replaced before the SPA, so the previous invite page reads the old name throughout a rollout. The alias is derived from the new field, so it describes the caller and is not the old account-existence oracle.
• Allow http: in the SPA's img-src, so a self-managed provider on a plain-HTTP deployment can show avatars and README images. img-src does not protect the session: https: already admits every host, and script-src, connect-src and form-action are unchanged.
• Write the nginx include init.sh generates under /tmp/codespace instead of /etc/nginx/codespace, so generating it needs nothing under /etc to be writable. This is the only write moved. The image does not yet start with a read-only root filesystem: dist/env.js is still substituted in place, npx keeps a cache, and nginx writes its pid file and cache directories.
• A page past MaxPage on the pull request list, the issue list and git.list_prs is now an empty page and the provider is not asked, instead of page 1000 again for a client that keeps paging. The MaxPage documentation on both queries says so.
• git.list_prs reads a number by its value. A number too large for an Int32 (3000000000) was taken for a missing page and read as page 1. It now counts as past the last page, or as the ceiling for a page size. A number written as 1001.0 or 1.001e3 is the whole number it says. A page size of 3000000000 is now 100, where it used to be the default of 30, and a fractional value is read at its whole part.

Test plan

• Unit: GitListPullRequestsNodeTests (36), covering overflow, fraction and exponent spellings, and the ceilings; session cookie and invitation preview wire tests; both list handlers. Full unit suite 13862 passed, 1 skipped.
• Integration: AgentToolReadBoundsFlowTests (9) through the real MCP handler, the pull request service and the GitLab provider against a loopback GitLab, including pages 2147483648 and 3000000000.
• E2E: sign-in, change-password and invitation accept with and without the CSRF header; invitation preview wire shape; the Pulls and Issues lists past the last page, and a page that does not fit an int, which binding refuses with a 400 (51 tests).
• Frontend (Node 22): static-hosting.test.ts and request.test.ts (58 tests), pnpm lint (0 errors), tsc --noEmit -p tsconfig.app.json.
• CI: frontend/docker/e2e/run.sh (spa-image build and run, checking the include at /tmp/codespace/api-origin.conf and nothing left under /etc/nginx/codespace). It was not run locally because Docker was unavailable.