docs: document PR3 shell UI and action kinds

docs/architecture.md

@@ -25,6 +25,12 @@ storage, requestAnimationFrame, or Date scheduling.
 resource and one timed action. M1 expands this into real resources, actions,
 story nodes, automation unlocks, and prestige definitions.
 
+Each action carries a behavior `kind` (`instant`, `loop`, `timed`, `story`,
+`context`) and a `group` (`{ id, label }`) used for UI layout. The schema
+enforces kind-specific invariants: `timed`/`loop` require `durationMs`, `timed`
+requires at least one yield, and `story` requires a `storyChoiceId` linking the
+action to a choice on the current story node.
+
 ## State
 
 `src/state/` owns environment coupling:
@@ -42,8 +48,39 @@ story nodes, automation unlocks, and prestige definitions.
 ## UI
 
 `src/ui/` renders the view model and calls runtime commands. Components should
-not implement gameplay rules. The M0 shell includes a resource readout, action
-panel, progress bar, and event log.
+not implement gameplay rules.
+
+### Shell layout
+
+PR3 replaces the M0/PR2 single-column overlay with a three-region shell
+(`AppShell.tsx`): a left **nav rail** (Play / Story / Settings / About), a
+**center** panel for the active tab, and a **right rail** shown on Play
+(resources, an inventory placeholder, and an optional event log gated by the
+`showEventLog` pref). `store.activePanel` selects the center panel; there is no
+modal overlay. New story beats raise a nav badge (`storyHasUnread`), and
+`storyOpenMode: auto` switches to the Story tab instead of opening an overlay.
+
+### Action kinds
+
+Play organizes actions into **columns by behavior kind**, ordered
+`instant → loop → timed → story → context`, with collapsible theme **groups**
+inside each column (collapse state persists in `prefs.collapsedActionGroups`).
+The pure engine dispatches each kind through `performAction` (`game.ts`):
+`instant` applies costs/yields immediately, `timed` enqueues, `loop` toggles an
+entry in `enabledLoopActionIds` (an idle runner starts the highest-priority
+affordable loop only when the queue is empty and only during live ticks, never
+offline), and `story` applies the linked choice. Story forks are taken **only**
+through Story-kind actions; the Story tab itself is read-only.
+
+### Story tab
+
+`StoryView.tsx` is a read-only 60/40 split: a branching `StoryTree` built from
+the story graph's choice/trigger edges (seen paths emphasized, unseen dimmed) and
+a scrollable `StoryProseLog` with no choice buttons. The boot intro shows a
+single Continue affordance that advances `boot_intro → fork_choice`; thereafter
+progression is driven by Story-kind actions.
+
+The full design lives in `docs/superpowers/specs/2026-06-11-m1-pr3-shell-ui-design.md`.
 
 ## Verification