Archive unify-auth-completion + sync spec delta (task 5.1)

Applies the ADDED requirement from
openspec/changes/unify-auth-completion/specs/authentication-methods/
into openspec/specs/authentication-methods/spec.md:

- Single web auth completion chokepoint (completeAuth at
  apps/journal/app/lib/auth/completion.server.ts) with five scenarios
  covering passkey register/login finish, magic-link verify-code,
  magic-link click-through, and returnTo sanitization.

Path in the synced requirement is .server.ts (the post-rename name),
not the .ts the delta originally captured.

Change moved to openspec/changes/archive/2026-05-08-unify-auth-completion/.
15/15 tasks complete.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

openspec/changes/unify-auth-completion/tasks.md

@@ -1,30 +0,0 @@
-## 1. New auth module structure
-
-- [x] 1.1 Create `apps/journal/app/lib/auth/` directory.
-- [x] 1.2 Create `apps/journal/app/lib/auth/session.ts` and move `sessionStorage`, `createSession`, `getSessionUser`, `destroySession` from `auth.server.ts` (preserve behaviour, including `process.env.SESSION_SECRET` source).
-- [x] 1.3 In `auth.server.ts`, re-export the moved helpers from `./auth/session.ts` so existing imports keep working unchanged. Add a JSDoc `@deprecated`-style comment pointing at the new path.
-
-## 2. completeAuth chokepoint
-
-- [x] 2.1 Write `apps/journal/app/lib/auth/completion.test.ts` (TDD red): scenarios for returnTo defaults to `/`, returnTo `//evil.com` rejected, returnTo `https://evil.com` rejected, response is a 302/303 redirect, response includes Set-Cookie naming `__session`.
-- [x] 2.2 Create `apps/journal/app/lib/auth/completion.ts` exporting `completeAuth({ userId, request, returnTo? }) → Promise<Response>` and a private `safeReturnTo(value)` helper. Implementation: `createSession(userId, request)`; `redirect(safeReturnTo(returnTo) ?? "/", { headers: { "Set-Cookie": cookie } })`. Terms recording is **not** here — both registration paths already record terms at user creation, so the chokepoint is purely session + redirect.
-- [x] 2.3 Run completion tests green.
-
-## 3. Caller migration
-
-- [x] 3.1 `apps/journal/app/routes/api.auth.register.ts` passkey-finish branch — replace inlined session+redirect with `return completeAuth({ userId, request, returnTo })`. Drop now-unused imports.
-- [x] 3.2 `apps/journal/app/routes/api.auth.login.ts` passkey `step: "finish-passkey"` branch — replace with `return completeAuth({ userId, request, returnTo })`.
-- [x] 3.3 `apps/journal/app/routes/api.auth.login.ts` magic-link `step: "verify-code"` branch — replace with `return completeAuth(...)`.
-- [x] 3.4 `apps/journal/app/routes/auth.verify.tsx` magic-link click-through consumer — replace with `return completeAuth(...)`.
-- [x] 3.5 Confirm no other callers of `createSession` remain inside auth route handlers (they should all flow through `completeAuth`). `getSessionUser` and `destroySession` continue to be called directly from non-completion sites — that's expected.
-
-## 4. Verification
-
-- [x] 4.1 `pnpm typecheck && pnpm lint && pnpm test` green.
-- [x] 4.2 `pnpm test:e2e` (auth flows) green without modification — proves behaviour-preserving refactor.
-- [x] 4.3 Manual sanity: register with passkey locally, login with passkey, log out, re-login via magic-link 6-digit code, click-through magic link from `auth.verify.tsx`. Confirm session cookie set + correct redirect each time. Verified 2026-05-08 over plain HTTP (HTTPS dev hits a pre-existing HTTP/2 + missing-Host issue with React Router 7.14's CSRF check — separate follow-up).
-
-## 5. Documentation + follow-up
-
-- [ ] 5.1 At archive time, apply the spec delta in `specs/authentication-methods/` to `openspec/specs/`.
-- [x] 5.2 Update import paths app-wide from `auth.server.ts` to `./auth/session.ts` and drop the re-exports. (Folded into this PR after the smoke test confirmed everything works.)