Fix medium-severity spec drift across 17 specs

- authentication-methods: document completeAuth mode param ("redirect"|"json");
  clarify add-passkey nudge (no dismiss mechanism, disappears on passkey add)
- journal-auth: session maxAge is 30 days; terms allow-list uses /legal/ prefix
  matching (broader than fixed list of paths)
- session-notes: mark awareness isolation and UndoManager isolation as not yet
  implemented (shared instances in current code)
- activity-feed: add fan-out scenario for visibility change to public
- explore: note that ?perPage is not yet implemented (hardcoded page size)
- multi-day-routes: add per-day GPX track split scenario (splitByDays option);
  document overnight vs isDayBreak naming gap
- osm-poi-overlays: debounce is 800ms + 2000ms min interval (not 500ms);
  retry is not automatic (fires on next viewport change)
- brouter-integration: rate limit corrected to 300/hour; add segment-cache
  requirement (client caches per-pair segments)
- wahoo-route-push: OAuth state shape uses camelCase (returnTo, pushAfter
  object) not snake_case with push_after boolean
- komoot-import: document noop adapter / ConnectedServiceManager bypass;
  note four Komoot-specific routes that bypass the generic OAuth framework
- background-jobs: exponential backoff not wired (retryLimit only); add SIGINT
- connected-services: add revoked status; name ConnectionNotActiveError
- infrastructure: add INTEGRATION_SECRET and SENTRY_DSN to env var lists;
  split secret decryption scenario by workflow (cd-apps vs cd-infra)
- secret-management: correct CD decryption — cd-apps only decrypts app.env;
  cd-infra decrypts both
- transactional-emails: welcome email is async (pg-boss job); magic-link email
  includes 6-digit numeric code
- journal-route-detail: websites are https: links (not mailto:); opening_hours
  is also displayed
- local-dev-environment: add mobile app (Expo) dev commands

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

openspec/specs/authentication-methods/spec.md

@@ -80,8 +80,9 @@ A signed-in user SHALL be able to add an additional passkey to their account fro
 - **THEN** a WebAuthn registration ceremony runs against the existing user id and a new row is inserted in `credentials` linked to that user
 
 #### Scenario: Post-login add-passkey nudge
-- **WHEN** a user has just verified via magic-link/code and lands on `/?add-passkey=1`
-- **THEN** the home page surfaces an "Add a passkey for faster sign-in" prompt; if dismissed it does not re-appear automatically
+- **WHEN** a user who has zero registered passkeys lands on `/?add-passkey=1`
+- **THEN** the home page surfaces an "Add a passkey for faster sign-in" prompt
+- **AND** once the user adds a passkey the prompt disappears (there is no separate dismiss/suppress mechanism)
 
 ### Requirement: Passkey deletion
 A signed-in user SHALL be able to remove a passkey from their account via the Security settings page (`/settings/security`). The Journal SHALL prevent deletion of the user's last remaining passkey if no alternative auth method (a verified email for magic-link login) is available, to avoid lock-out.
@@ -99,6 +100,8 @@ Every successful web authentication flow — passkey register-finish, passkey lo
 
 Per-method identity verification (WebAuthn ceremony, magic-token consumption, 6-digit-code consumption) SHALL run in its own function and produce a `userId` *before* `completeAuth` is invoked. `completeAuth` SHALL NOT know how identity was proved.
 
+`completeAuth` supports two response modes via an optional `mode` parameter: `"redirect"` (default, for browser flows — returns a `Response` with `Set-Cookie` + `Location`) and `"json"` (for API/mobile flows — returns a JSON body with the session token). All web authentication scenarios use `"redirect"`; the `"json"` mode is used by the OAuth2/PKCE mobile code-exchange flow.
+
 Terms recording happens at user creation time inside the per-method registration functions (`finishRegistration` for passkey, `registerWithMagicLink` for magic-link), not inside `completeAuth`. The Terms gate (root-loader redirect for cookie sessions; `requireApiUser` 403 for bearer-token API requests) SHALL remain the enforcement point for stale `terms_version`.
 
 OAuth-code issuance at `/oauth/authorize` SHALL NOT be routed through `completeAuth` — that flow operates on an already-authenticated user and shares only the trailing redirect, not the full sequence.