docs: a trip is a sequence of parts, each with its own place and dates

README.md

@@ -51,7 +51,8 @@ one.
   one.
 - **Air consumption** — SAC and RMV are derived automatically, including a **per-tank breakdown**
   across recorded gas switches on multi-tank dives, with a consumption trend chart on the dashboard.
-- **Trips** — group dives into a liveaboard or a holiday week, with location and dates.
+- **Trips** — group dives into a liveaboard or a holiday week, a part at a time: each part carries
+  its own place and its own dates, and the trip spans them all.
 - **Dive sites** — your personal site list, with every dive you've logged at each site.
 - **Gear tracking** — your equipment with per-item dive counts, groupable into gear sets you can
   attach to a dive in one click, plus **service schedules** (annual service, visual inspection,

src/components/courses/course-dialog.tsx

@@ -329,8 +329,8 @@ export function CourseDialog({
                 name="end_date"
                 render={({ field }) => (
                   <FormItem>
-                    {/* Neither date is required, unlike a trip's start date: a
-                        course that is only booked has no dates yet. */}
+                    {/* Neither date is required: a course that is only
+                        booked has no dates yet. */}
                     <FormLabel>End date</FormLabel>
                     <FormControl>
                       <DatePicker

src/hooks/useInfiniteResource.test.tsx

@@ -42,7 +42,8 @@ function ledger(total = 30, perPage = 10) {
     /**
      * Simulates an edit that changes the column the server sorts by, moving the
      * row to `to` in the order. Every list here is sorted by something an edit
-     * dialog can change - a dive site's name, a trip's start date.
+     * dialog can change - a dive site's name, the earliest date across a trip's
+     * parts.
      */
     moveServerSide: (uuid: string, to: number) => {
       const row = rows.find((one) => one.uuid === uuid)!;

src/hooks/useInfiniteResource.ts

@@ -304,11 +304,12 @@ export function useInfiniteResource<T>(
    * The cursor steps back a page for the same reason `removeItem` re-derives
    * it, and is re-derived rather than decremented for the same reason too.
    * Every list here is ordered by a column the edit dialog can change - dive
-   * sites by name, trips and courses by start date, certifications by the date
-   * certified - so a rename or a re-dated trip *moves* the row in the server's
-   * order. Move it later than the loaded window and everything after its old
-   * slot shifts up one offset, so asking for the page after the last one fetched
-   * skips whichever row slid across the boundary, permanently. Re-reading the
+   * sites by name, courses by start date, trips by the earliest date across
+   * their parts, certifications by the date certified - so a rename or a
+   * re-dated trip *moves* the row in the server's order. Move it later than the
+   * loaded window and everything after its old slot shifts up one offset, so
+   * asking for the page after the last one fetched skips whichever row slid
+   * across the boundary, permanently. Re-reading the
    * previous page covers a shift of one row in either direction and the dedup in
    * `load` absorbs the repeats; the cost is one overlapping request on the next
    * scroll, however many edits it follows.

src/lib/api/courses.ts

@@ -35,10 +35,10 @@ export const DEFAULT_COURSE_STATUS: CourseStatus = "completed";
 /**
  * A training course: a group of dives and the certifications they produced.
  *
- * Works like a trip without a location. The instructor/training-center trio
- * duplicates the same fields on `Certification` deliberately - a certification
- * has to stand alone, because imported history arrives certification-first with
- * no course to hang them on.
+ * Works like a trip, but with dates of its own and no place. The
+ * instructor/training-center trio duplicates the same fields on `Certification`
+ * deliberately - a certification has to stand alone, because imported history
+ * arrives certification-first with no course to hang them on.
  */
 export interface Course {
   uuid: string;
@@ -50,8 +50,8 @@ export interface Course {
   // Only set when `agency` is `other` - the name of the training body.
   agency_other?: string | null;
   status: CourseStatus;
-  // Both nullable, unlike a trip's start date: a `planned` course has no dates
-  // yet, and a referral spans months with fuzzy edges. Bare "YYYY-MM-DD".
+  // Both nullable: a `planned` course has no dates yet, and a referral spans
+  // months with fuzzy edges. Bare "YYYY-MM-DD".
   start_date?: string | null;
   end_date?: string | null;
   instructor_name?: string | null;

src/lib/date-time.ts

@@ -311,9 +311,9 @@ export function formatDiveStartTime(startTime: string): string {
   return `${date} at ${formatDiveTimeOnly(startTime)}${zone}`;
 }
 
-// Formats a plain "YYYY-MM-DD" date (no time component, e.g. a trip's start
-// or end date) without going through timezone-sensitive UTC parsing - using
-// `new Date(dateString)` directly can shift the displayed day by one in
+// Formats a plain "YYYY-MM-DD" date (no time component, e.g. a trip part's
+// start or end date) without going through timezone-sensitive UTC parsing -
+// using `new Date(dateString)` directly can shift the displayed day by one in
 // negative-UTC-offset timezones since bare date strings parse as UTC midnight.
 export function formatDateOnly(
   dateString: string,
@@ -410,7 +410,8 @@ export function formatDurationHoursMinutes(durationSeconds: number): string {
   return minutes > 0 ? `${hours}h ${minutes}min` : `${hours}h`;
 }
 
-// Formats a trip's start/end date range for display, e.g. "Jun 1 - Jun 8, 2024".
+// Formats a date range - a trip's span, a course's dates - for display, e.g.
+// "Jun 1 - Jun 8, 2024".
 // Returns `undefined` if neither date is set.
 export function formatTripDateRange(
   startDate?: string,