Navigation Picker (Multi-App Launch Screen)

Figure 7. Navigation Picker: post‑commit (or Resume > Navigate) screen offering Google Maps, Apple Maps, or Waze with preloaded route + waypoints and trip summary context.

1. Purpose

Provide a frictionless handoff from planning to real-world movement. Users select their preferred navigation app and continue the itinerary with correct ordering of key Petals (POIs) and timing assumptions.

Appears when:

• User taps “Navigate” from: Trip In Progress (after save) or a committed trip view.
• User resumes a trip mid-route and requests directions.

2. Core Elements

Element	Description	Notes
Title Block	“Navigate” + Trip Name	Trip name truncated w/ ellipsis after 1 line
Prompt	“Which app would you like to use?”	Localized string key: nav_picker.prompt
App Option Cards	Icon + Label + Right Arrow (focusable)	Order = last used first (persisted)
Route Summary	Distance, total petals, estimated travel time	Travel time cached from last generation or on-demand calc
Context Chip Strip	Mode icons (🚐, 🚲) + companions tags	Reinforces personalization
Dismiss / Back	Returns user to trip view	ESC / swipe-down on mobile sheet variant

3. Deep Link Formats

Provider	Link Template	Waypoint Support	Notes
Google Maps	https://www.google.com/maps/dir/?api=1&origin={lat1},{lon1}&destination={latN},{lonN}&waypoints={lat2},{lon2}\|...	Up to ~10 consumer waypoints	Encode travelmode=driving\|bicycling when relevant
Apple Maps	http://maps.apple.com/?saddr={lat1},{lon1}&daddr={latN},{lonN}	Limited (multi via daddr=lat,long+to:lat,long)	Fallback: only origin/destination if > 1 mid stop
Waze	https://waze.com/ul?ll={latN},{lonN}&navigate=yes	Single destination	Sequential multi-stop: relaunch after each arrival (optional prompt)

Waypoint Compression Strategy

1. Always include origin (first segment start) and final destination (last overnight / end Petal).
2. Include intermediate high-value Petals (priority order: explicit user “must keep” flags > overnight > longest duration > scenic rating).
3. If waypoint limit exceeded: collapse adjacent low-impact stops into a single instruction summary note (shown in an inline tip before launch).

4. Route Summary Construction

Metric	Source	Fallback
Total Distance	Precomputed aggregator on commit	On-demand distance matrix if stale > 6h
Est Travel Time	Summed drive segments + buffer (traffic factor)	Live request to provider ETA API (if token budget)
Petal Count	Length of segment array (activity segments only)	n/a
Modes Present	Aggregated from segment tags	Derive from icons table

5. Telemetry

Event	Payload Example
nav_picker_view	{tripId, userId, candidateProviders:["google","apple","waze"], petals:11}
nav_picker_select	{tripId, provider:"google", waypoints:7}
nav_picker_limit_trim	{tripId, removed:3, kept:7}
nav_launch_error	{tripId, provider:"apple", code:"APP_NOT_AVAILABLE"}
nav_relaunch_next_stop	{tripId, provider:"waze", nextStopId:"snagov_lake"}

6. Error / Edge Handling

Scenario	Handling
App not installed (mobile)	Detect scheme failure → show inline sheet offering other apps + “Copy route link”
Excess waypoints	Apply compression strategy; show toast: “Simplified route (some short stops grouped).”
Offline / low connectivity	Present cached polyline static preview + allow copy coordinates
Mixed travel modes (e‑bike + drive)	Prefer driving for backbone; inject note: “Segment 3 is ride-only – switch to cycling after parking.”
Permission denied (location)	Prompt OS request; if denied, fallback to origin as first Petal coordinates

7. Accessibility

• Each app card: role=button + aria-label="Open in Google Maps" style pattern.
• Keyboard order: top to bottom, Enter to launch, Space to focus details.
• Focus ring meets contrast AA (outline offset 2px, brand accent color).
• Voice summary preceding list: screen reader live region describing route summary.

8. Security & Privacy Notes

Concern	Mitigation
Leaking personal waypoint names in URL	Use sanitized short labels or omit names; rely on coordinates
Over-sharing user profile tags	Keep companions/mode local; not embedded in external link
Stale link reuse	Append ephemeral ts query param so analytics can detect outdated launches

9. Future Enhancements

• Add “Copy GPX” / “Download KML” for advanced offline use.
• Offer cycling vs driving route toggle (Google & Apple only) prior to launch.
• Multi-day navigation segmentation (launch Day N subset only).
• Auto-detect installed apps and gray out unavailable options on desktop.

---

Figure 7 added: 2025-09-05 (image pending upload as navigation-picker.png)

10. Implementation Checklist (Dev Aid)

Item	Status
Decide waypoint selection heuristic	Planned
Implement provider detection (UA + scheme probe)	Planned
Add telemetry hooks	Planned
Compression & toast messaging	Planned
Accessible card semantics	Planned

---

Cross-links: trip-in-progress.md, itinerary-map-page.md, itinerary-refinement-detail.md