diff --git a/openspec/changes/multi-day-routes/design.md b/openspec/changes/multi-day-routes/design.md
index 2ad3e7b..48aad3b 100644
--- a/openspec/changes/multi-day-routes/design.md
+++ b/openspec/changes/multi-day-routes/design.md
@@ -192,6 +192,94 @@ Visual feedback follows visual-redesign tokens:
 - The "OVERNIGHT" badge uses `--stop` text on `--stop-bg` background with
   `--stop-border` border
 
+### D9: GPX parse recognizes overnight waypoints
+
+The `parseWaypoints` function in `packages/gpx/src/parse.ts` is extended to
+check for `<type>overnight</type>` inside `<wpt>` elements. When found, the
+returned `Waypoint` has `isDayBreak: true`.
+
+```typescript
+function parseWaypoints(doc: Document): Waypoint[] {
+  const wpts = doc.querySelectorAll("wpt");
+  return Array.from(wpts).map((wpt) => {
+    const lat = parseFloat(wpt.getAttribute("lat") ?? "0");
+    const lon = parseFloat(wpt.getAttribute("lon") ?? "0");
+    const name = wpt.querySelector("name")?.textContent ?? undefined;
+    const type = wpt.querySelector("type")?.textContent ?? undefined;
+    const isDayBreak = type === "overnight" ? true : undefined;
+    return { lat, lon, name, isDayBreak };
+  });
+}
+```
+
+This makes GPX round-tripping work: Planner exports overnight waypoints with
+`<type>overnight</type>` (D7), and any consumer — the Journal's `updateRoute`,
+the Planner's GPX import, or a future mobile app — gets `isDayBreak` back.
+
+### D10: Journal stores dayBreaks on route save
+
+The `dayBreaks` jsonb column on `journal.routes` already exists. When
+`updateRoute` receives GPX and calls `parseGpxAsync`, it extracts the indices
+of waypoints where `isDayBreak === true` and writes them to `dayBreaks`:
+
+```typescript
+const parsed = await parseGpxAsync(gpx);
+const dayBreaks = parsed.waypoints
+  .map((w, i) => (w.isDayBreak ? i : -1))
+  .filter((i) => i >= 0);
+```
+
+This is computed on write, not on read — the Journal doesn't need to re-parse
+GPX to know day structure. If the GPX has no overnight waypoints, `dayBreaks`
+is an empty array (single-day route).
+
+### D11: Journal route detail day breakdown
+
+When a route has non-empty `dayBreaks`, the route detail page shows a day
+breakdown section below the stats grid. Per-day stats (distance, ascent,
+descent) are computed from the stored GPX by splitting at day-break waypoints
+— reusing the same `computeDays` logic from D2, extracted into
+`@trails-cool/gpx` so both Planner and Journal can use it.
+
+```
+DAY 1: Berlin → Dessau    120 km  ↑340m  ↓180m
+DAY 2: Dessau → Erfurt    223 km  ↑528m  ↓490m
+```
+
+The map also colors each day segment differently (alternating two colors from
+the design tokens) so users can visually see where each day starts and ends.
+
+For single-day routes (no `dayBreaks`), nothing changes — the page renders
+exactly as it does today.
+
+### D12: computeDays as a shared package function
+
+The `computeDays` pure function (D2) is placed in `@trails-cool/gpx` rather
+than in the Planner app, since both the Planner (from Yjs + EnrichedRoute) and
+the Journal (from parsed GPX) need day computation. The function signature
+works with the `GpxData` tracks and waypoints returned by `parseGpx`:
+
+```typescript
+interface DayStage {
+  dayNumber: number;
+  startWaypointIndex: number;
+  endWaypointIndex: number;
+  startName?: string;
+  endName?: string;
+  distance: number;      // meters
+  ascent: number;        // meters
+  descent: number;       // meters
+}
+
+function computeDays(
+  waypoints: Waypoint[],
+  tracks: TrackPoint[][],
+): DayStage[];
+```
+
+The Planner's `useDays()` hook maps its Yjs waypoints + EnrichedRoute into
+this same shape before calling `computeDays`.
+
 ## Risks / Trade-offs
 
 - **Segment boundary alignment**: The day computation relies on
diff --git a/openspec/changes/multi-day-routes/proposal.md b/openspec/changes/multi-day-routes/proposal.md
index bb8cbbe..e09b6b3 100644
--- a/openspec/changes/multi-day-routes/proposal.md
+++ b/openspec/changes/multi-day-routes/proposal.md
@@ -44,6 +44,9 @@ the data model, computation logic, and integration wiring.
 - `planner-session`: Waypoints gain an `overnight` property in Yjs state
 - `map-display`: Day boundary labels on route, overnight marker styling
 - `gpx-export`: Day-break metadata in exported GPX waypoints
+- `gpx-import`: Parse `<type>overnight</type>` waypoints to restore day breaks
+- `route-management`: Populate `dayBreaks` column on save, expose per-day stats
+- `journal-route-detail`: Day breakdown display with per-day stats and map segments
 
 ## Non-Goals
 
@@ -52,8 +55,9 @@ the data model, computation logic, and integration wiring.
 - **Accommodation search**: No POI lookup for campsites or hotels. Out of scope.
 - **Per-day routing profiles**: All days use the same BRouter profile. Supporting
   different profiles per day would require rearchitecting the routing pipeline.
-- **Journal integration**: Saving multi-day routes to the Journal is a separate
-  concern (route-features change). This spec is Planner-only.
+- **Per-day activity tracking**: Linking individual activities to specific days
+  of a multi-day route (e.g. "Day 2 activity"). Activities remain linked to the
+  full route. Per-day activity chaining is a future concern.
 
 ## Impact
 
@@ -67,6 +71,13 @@ the data model, computation logic, and integration wiring.
   sections and overnight toggle buttons
 - **ElevationChart**: Canvas drawing extended with vertical day dividers
 - **Map**: New day-label layer and overnight marker variant
-- **GPX**: `generateGpx` extended to emit `<type>overnight</type>` on day-break
-  waypoints
+- **GPX generate**: `generateGpx` extended to emit `<type>overnight</type>` on
+  day-break waypoints
+- **GPX parse**: `parseGpx` extended to recognize `<type>overnight</type>` and
+  set `isDayBreak: true` on parsed waypoints
+- **Journal route storage**: `updateRoute` populates `dayBreaks` column from
+  parsed waypoint indices when saving GPX
+- **Journal route detail**: Day breakdown section with per-day stats (distance,
+  ascent, descent) when `dayBreaks` is non-empty
 - **i18n**: New keys for day labels, overnight toggle, per-day stats (en + de)
+  in both planner and journal namespaces
diff --git a/openspec/changes/multi-day-routes/tasks.md b/openspec/changes/multi-day-routes/tasks.md
index d6f984d..717fbcd 100644
--- a/openspec/changes/multi-day-routes/tasks.md
+++ b/openspec/changes/multi-day-routes/tasks.md
@@ -1,8 +1,8 @@
 ## 1. Data Model & Computation
 
 - [ ] 1.1 Add `overnight` property support to Yjs waypoint Y.Maps: helper functions `setOvernight(yjs, index, value)` and `isOvernight(yMap)` in a new `apps/planner/app/lib/overnight.ts`
-- [ ] 1.2 Create `apps/planner/app/lib/compute-days.ts` with `computeDays()` pure function: takes waypoints array + `EnrichedRoute`, returns `DayStage[]` (day number, waypoint range, coord range, distance, ascent, descent, estimated time)
-- [ ] 1.3 Create `useDays()` hook in `apps/planner/app/lib/use-days.ts`: observes Yjs waypoints + routeData, calls `computeDays()`, returns reactive `DayStage[]`
+- [ ] 1.2 Create `computeDays()` pure function in `packages/gpx/src/compute-days.ts`: takes `Waypoint[]` + `TrackPoint[][]`, returns `DayStage[]` (day number, waypoint range, distance, ascent, descent). Export from package index.
+- [ ] 1.3 Create `useDays()` hook in `apps/planner/app/lib/use-days.ts`: maps Yjs waypoints + EnrichedRoute into `computeDays()` input, returns reactive `DayStage[]`
 
 ## 2. Sidebar Day Breakdown
 
@@ -22,19 +22,30 @@
 - [ ] 4.1 Add day divider rendering to `ElevationChart`: dashed vertical lines at overnight waypoint distances with "Day N" labels at top
 - [ ] 4.2 Show per-day distance ranges on x-axis labels (e.g. "120 km" at each day boundary)
 
-## 5. GPX Export
+## 5. GPX Roundtrip
 
 - [ ] 5.1 Extend `generateGpx` in `@trails-cool/gpx` to emit `<type>overnight</type>` for waypoints with `isDayBreak: true`
-- [ ] 5.2 Add multi-track export option: split track into one `<trk>` per day, each named "Day N: Start - End"
+- [ ] 5.2 Extend `parseGpx` in `@trails-cool/gpx` to recognize `<type>overnight</type>` and set `isDayBreak: true` on parsed waypoints
+- [ ] 5.3 Add multi-track export option: split track into one `<trk>` per day, each named "Day N: Start - End"
 
-## 6. i18n
+## 6. Journal Integration
 
-- [ ] 6.1 Add translation keys for en + de: day labels ("Day 1", "Tag 1"), overnight toggle ("Mark as overnight stop" / "Als Ubernachtung markieren"), per-day stats, route summary
+- [ ] 6.1 Update `updateRoute` in `apps/journal/app/lib/routes.server.ts` to extract `dayBreaks` indices from parsed GPX waypoints and write to `dayBreaks` column
+- [ ] 6.2 Expose `dayBreaks` and per-day stats in route detail loader (`routes.$id.tsx`)
+- [ ] 6.3 Add day breakdown section to route detail page: per-day distance, ascent, descent, start/end names — shown only when dayBreaks is non-empty
+- [ ] 6.4 Color route map segments per day (alternating colors) on the route detail map when dayBreaks exist
 
-## 7. Testing
+## 7. i18n
 
-- [ ] 7.1 Unit tests for `computeDays()`: single day (no overnight), two days, three days, empty route, single waypoint, overnight on first/last waypoint edge cases
-- [ ] 7.2 Unit tests for `overnight.ts` helpers: set/clear/check overnight on Y.Map
-- [ ] 7.3 Unit tests for GPX export with overnight waypoints: verify `<type>overnight</type>` output, multi-track splitting
-- [ ] 7.4 E2E test: add waypoints, toggle overnight on one, verify sidebar shows day breakdown with correct stats
-- [ ] 7.5 E2E test: export GPX with day breaks, verify downloaded file contains overnight metadata
+- [ ] 7.1 Add Planner translation keys for en + de: day labels ("Day 1", "Tag 1"), overnight toggle ("Mark as overnight stop" / "Als Übernachtung markieren"), per-day stats, route summary
+- [ ] 7.2 Add Journal translation keys for en + de: day breakdown header, per-day stats labels
+
+## 8. Testing
+
+- [ ] 8.1 Unit tests for `computeDays()`: single day (no overnight), two days, three days, empty route, single waypoint, overnight on first/last waypoint edge cases
+- [ ] 8.2 Unit tests for `overnight.ts` helpers: set/clear/check overnight on Y.Map
+- [ ] 8.3 Unit tests for GPX roundtrip: generate with `isDayBreak`, parse back, verify `isDayBreak` preserved
+- [ ] 8.4 Unit tests for `dayBreaks` extraction in route update logic
+- [ ] 8.5 E2E test: add waypoints, toggle overnight on one, verify sidebar shows day breakdown with correct stats
+- [ ] 8.6 E2E test: export GPX with day breaks, verify downloaded file contains overnight metadata
+- [ ] 8.7 E2E test: save multi-day route to Journal, verify day breakdown displays on route detail page