Refactor _build_user_prompt function in enrich_trip.py to simplify unit system handling

- Removed parameters for unit distance and temperature, standardizing to kilometers and Celsius.
- Updated user prompt messages to reflect the new fixed unit system, enhancing clarity and consistency.

Author: maplethorpej

app/tasks/enrich_trip.py

@@ -114,14 +114,10 @@
 ]
 
 
-def _build_user_prompt(trip: Trip, unit_distance: str, unit_temperature: str) -> str:
-    dist_label = "miles" if unit_distance == "MI" else "kilometers"
-    elev_label = "feet" if unit_distance == "MI" else "meters"
-    temp_label = "Fahrenheit" if unit_temperature == "F" else "Celsius"
-
+def _build_user_prompt(trip: Trip) -> str:
     lines = [
         f"Trail/Location: {trip.location}",
-        f"Unit system: distance in {dist_label}, elevation in {elev_label}, temperature in {temp_label}",
+        "Unit system: distance in kilometers, elevation in meters, temperature in Celsius",
         "",
     ]
 
@@ -136,12 +132,12 @@ def _build_user_prompt(trip: Trip, unit_distance: str, unit_temperature: str) ->
     lines.append("Current field status:")
 
     field_labels = {
-        "distance": f"Distance ({dist_label})",
-        "daily_elevation_gain": f"Daily elevation gain ({elev_label})",
+        "distance": "Distance (kilometers)",
+        "daily_elevation_gain": "Daily elevation gain (meters)",
         "terrain": "Terrain type",
         "pace": "Pace",
-        "temp_min": f"Temperature min ({temp_label})",
-        "temp_max": f"Temperature max ({temp_label})",
+        "temp_min": "Temperature min (Celsius)",
+        "temp_max": "Temperature max (Celsius)",
         "temp_category": "Temperature category",
         "trail_system": "Trail system",
     }
@@ -188,13 +184,10 @@ def enrich_trip(self, trip_id: int):
         trip.enrich_status = "processing"
         session.commit()
 
-        unit_distance = user.unit_distance or "MI"
-        unit_temperature = user.unit_temperature or "F"
-
         logger.info("Enriching trip %s: %s", trip_id, trip.location)
 
         try:
-            user_prompt = _build_user_prompt(trip, unit_distance, unit_temperature)
+            user_prompt = _build_user_prompt(trip)
             response = ai_complete(
                 system=SYSTEM_PROMPT,
                 user=user_prompt,

migrations/canonical_units.sql

@@ -0,0 +1,53 @@
+-- Canonical Units Migration
+-- Converts existing trip and hiker profile data to canonical metric units.
+-- All numeric trip fields will be stored as: km, meters, °C
+-- All hiker profile fields will be stored as: kg, cm
+--
+-- IMPORTANT: Run this migration BEFORE deploying the new frontend code.
+-- The new frontend expects all DB values to be in metric.
+--
+-- This migration is idempotent for metric users (multiplying by 1 effectively).
+-- For imperial users, it converts their data to metric.
+
+BEGIN;
+
+-- Step 1: Convert trip distance (miles -> km) and elevation (feet -> meters)
+-- for users whose unit_distance is 'MI'
+UPDATE trip
+SET
+  distance = ROUND(CAST(distance * 1.60934 AS NUMERIC), 2),
+  daily_elevation_gain = ROUND(CAST(daily_elevation_gain * 0.3048 AS NUMERIC), 0)
+FROM "user"
+WHERE trip.user_id = "user".id
+  AND "user".unit_distance = 'MI'
+  AND (trip.distance IS NOT NULL OR trip.daily_elevation_gain IS NOT NULL);
+
+-- Step 2: Convert trip temperatures (°F -> °C)
+-- for users whose unit_temperature is 'F' or NULL (default is F)
+UPDATE trip
+SET
+  temp_min = ROUND(CAST((temp_min - 32) * 5.0 / 9.0 AS NUMERIC), 0),
+  temp_max = ROUND(CAST((temp_max - 32) * 5.0 / 9.0 AS NUMERIC), 0)
+FROM "user"
+WHERE trip.user_id = "user".id
+  AND (COALESCE("user".unit_temperature, 'F') = 'F')
+  AND (trip.temp_min IS NOT NULL OR trip.temp_max IS NOT NULL);
+
+-- Step 3: Convert hiker profile weight (lb -> kg) and height (in -> cm)
+-- for users whose unit_weight is 'IMPERIAL'
+UPDATE hikerprofile
+SET
+  weight = ROUND(CAST(weight * 0.453592 AS NUMERIC), 1),
+  height = ROUND(CAST(height * 2.54 AS NUMERIC), 1)
+FROM "user"
+WHERE hikerprofile.user_id = "user".id
+  AND "user".unit_weight = 'IMPERIAL'
+  AND (hikerprofile.weight IS NOT NULL OR hikerprofile.height IS NOT NULL);
+
+-- Step 4: Set unit_temperature for users who have it NULL/empty
+-- so the new settings UI has a known starting value
+UPDATE "user"
+SET unit_temperature = 'F'
+WHERE unit_temperature IS NULL OR unit_temperature = '';
+
+COMMIT;