Node 9Phase IAPage-level

System Pages

Not found, server error, maintenance, consent, and toasts: the app's connective tissue.

Job: None directly; these protect the calm-and-trust experience when something goes wrong.

Type: States, Sections

Step 3

System pages

The cross-cutting states owned by no cluster: not found, server error, maintenance, the consent banner, and toasts.

Decisions

Recommendations

Not found and server error keep the chrome where possible and always offer a way back to Home; a true server 404/500 gets a minimal standalone template.
No full-app maintenance page at MVP: sync-provider outages are per-source (needs-reauth, sync-error), not whole-app downtime.
The consent banner is [?], tied to whether PostHog sets a non-essential cookie and the deferred EU review (D5).
Toasts are non-blocking, auto-dismissing, one action max, distinct from blocking dialogs.

Block order

Nodes 9.1 to 9.5

State

9.1 Not found (in-app)

P"We could not find that."
S"The page may have moved, or the link may be old."
P"Back to my list" → Home

State

9.2 Server error

P"Something went wrong on our side."
S"This is usually temporary."
P"Refresh" and "Back to Home"

Section [?]

9.4 Consent banner

PPlain statement of what is set and why [? pending cookie decision]
P"Accept" and "Only essential", equal choices
SLink to the privacy explanation

Section

9.5 Toasts

P"Subscription added."
P"Removed." with "Undo"
S"Couldn't refresh, showing your last update."

States

State	Reads like	Trigger
9.1 not-found	Calm heading plus "Back to my list", chrome intact	Unknown in-app route
9.2 server-error	Standalone minimal template, Refresh / Home	Hard load or backend failure
9.3 maintenance	Not built	n/a at MVP
9.4 consent	Conditional banner	[? only if a non-essential cookie is set]
9.5 toast	"Added", "Saved", "Removed / Undo"	A routine action

Variants

Mockups

9.1 Not found

We could not find that

The page may have moved, or the link may be old.

Back to my list

9.2 Server error

Something went wrong on our side

This is usually temporary.

RefreshBack to Home

9.5 Toast, undoable

Removed.

Undo

9.5 Toast, recoverable

Couldn't refresh, showing your last update.

Cross-cutting

SEO, Accessibility, Mobile

SEO. In-app not-found is noindex; a true server 404 returns a real 404 status. No schema.

Accessibility. Headings are the focus target; the server-error template does not depend on app JS; toasts use role=status, undo is reachable for the toast lifetime; the consent banner does not trap and offers equal choices.

Mobile. No structural delta; toasts anchor above the tab bar on mobile, to a corner on desktop.

Status

Locked (draft, 2026-07-03) / Open

Locked. Calm not-found and server error with a way home; no maintenance page at MVP; toasts non-blocking and distinct from dialogs.

Still [?]. The consent banner, pending the PostHog cookie decision and the deferred EU review.