Resolve any occurrence back to its rule, and count what a repeat adds strands

The lists only ever build allRows from a rule's first two occurrences
(LIST_OCCURRENCES), but the timeline draws every occurrence the board window
admits. Clicking a bar past the second set openId to an id allRows could not
resolve, so the detail sheet silently failed to open and per-occurrence
completion was unreachable for those bars. occurrenceForId parses the day an
occurrence id names and regenerates just that neighbourhood via occurrencesOf,
so App.tsx can resolve through the rule when the direct lookup misses.

Separately, strandedBy's `if (record.repeat === null) return 0` hid the
warning on exactly the transition where it matters most: a reader marks a
plain event done, then edits it to add a repeat, and the save re-keys every
row from `id` to `id#<date>` with no notice that the mark under the bare id
is about to become unreachable. strandedOccurrences checks the record's own
id when it has no repeat yet, and its next occurrences once it does.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

src/client/App.tsx

@@ -30,11 +30,12 @@ import {
 } from "./state/lens.ts";
 import { clockFor, formatRemaining } from "../shared/time.ts";
 import { dailySummary, isDaily, resolveDaily } from "../shared/daily.ts";
-import { nextOccurrences } from "../shared/recurrence.ts";
+import { occurrenceForId, strandedOccurrences } from "../shared/recurrence.ts";
 import { orderGames } from "./state/gameOrder.ts";
 import { GameMetaProvider, type MetaResolver } from "./state/gameMeta.tsx";
 import { metaOnTheme, useTheme } from "./state/theme.ts";
 import {
+  asOccurrenceEvent,
   recordFor,
   type CustomEvents,
   type CustomGames,
@@ -357,7 +358,24 @@ export function App() {
   );
   const perGame = useMemo(() => countByGame(scopedTodo), [scopedTodo]);
 
-  const openRow = allRows.find((r) => r.event.id === openId) ?? null;
+  /**
+   * The lists only ever build `allRows` from a rule's first two occurrences
+   * (`LIST_OCCURRENCES`), but the timeline draws every occurrence the board
+   * window admits — so a bar past the second names an id `allRows` cannot
+   * resolve. Resolved through the rule behind it rather than dropped, or every
+   * later bar would be a dead click with no way to reach per-occurrence
+   * completion.
+   */
+  const openRow = (() => {
+    const hit = allRows.find((r) => r.event.id === openId) ?? null;
+    if (hit !== null || openId === null) return hit;
+    const record = recordFor(custom.events, openId);
+    if (record === undefined) return null;
+    const occurrence = occurrenceForId(record, openId);
+    if (occurrence === null) return null;
+    const event = asOccurrenceEvent(record, occurrence);
+    return { event, clock: clockFor(event, prefs.region, now) };
+  })();
 
   /** One row, wired up. Both lists render the same thing from the same props. */
   const renderRow = (row: RowEvent) => (
@@ -706,19 +724,14 @@ export function App() {
               onSave: (_id: string, draft: EventDraft) =>
                 custom.editEvent(record.id, draft),
               onDelete: () => custom.removeEvent(record.id),
-              strandedBy: () => {
-                // What the reader has actually recorded against the occurrences
-                // this rule generates today, and would no longer reach once the
-                // ids move. Twelve is a season of a fortnightly rule — enough to
-                // make the number meaningful without walking a decade of a
-                // daily one.
-                if (record.repeat === null) return 0;
-                return nextOccurrences(record, now, 12).filter(
-                  (o) =>
-                    prog.progress[o.id] !== undefined ||
-                    (daily.logs[o.id]?.days.length ?? 0) > 0,
-                ).length;
-              },
+              strandedBy: () =>
+                strandedOccurrences(
+                  record,
+                  now,
+                  (id) =>
+                    prog.progress[id] !== undefined ||
+                    (daily.logs[id]?.days.length ?? 0) > 0,
+                ),
             };
           })()}
         />