Refactor codebase

app/__init__.py

@@ -1,10 +1,7 @@
-from datetime import datetime, timezone, timedelta
 from flask import Flask
-from app.config import Config
+from app.config import Config, SYDNEY_TZ
 from app.db import init_db, close_db
 
-SYDNEY_TZ = timezone(timedelta(hours=11))
-
 
 def create_app():
     app = Flask(__name__)
@@ -17,12 +14,17 @@ def create_app():
     # Jinja2 filter: convert UTC to Sydney time
     @app.template_filter('sydney')
     def sydney_time_filter(dt, fmt='%d %b %Y, %H:%M'):
+        from datetime import timezone
         if dt is None:
             return ''
         if dt.tzinfo is None:
             dt = dt.replace(tzinfo=timezone.utc)
         return dt.astimezone(SYDNEY_TZ).strftime(fmt)
 
+    # Make milestone labels available to all templates
+    from app.utils import MILESTONE_LABELS
+    app.jinja_env.globals['MILESTONE_LABELS'] = MILESTONE_LABELS
+
     # Register blueprints
     from app.routes.auth import bp as auth_bp
     from app.routes.dashboard import bp as dashboard_bp

app/auth.py

@@ -1,5 +1,5 @@
 from functools import wraps
-from flask import session, redirect, url_for, request
+from flask import session, redirect, url_for, request, jsonify
 from app.db import query_one
 
 
@@ -19,3 +19,19 @@ def get_current_user():
     if user_id is None:
         return None
     return query_one("SELECT * FROM users WHERE id = %s", (user_id,))
+
+
+def privacy_guard(f):
+    """Decorator for API endpoints that take a user_id parameter.
+
+    If the requested user is private and is not the current session user,
+    returns an empty JSON response instead of the actual data.
+    """
+    @wraps(f)
+    def decorated_function(user_id, *args, **kwargs):
+        if user_id != session.get("user_id"):
+            target = query_one("SELECT is_private FROM users WHERE id = %s", (user_id,))
+            if target and target["is_private"]:
+                return jsonify({})
+        return f(user_id, *args, **kwargs)
+    return decorated_function

app/config.py

@@ -1,8 +1,12 @@
 import os
+from datetime import timezone, timedelta
 from dotenv import load_dotenv
 
 load_dotenv()
 
+# Application-wide timezone for display formatting
+SYDNEY_TZ = timezone(timedelta(hours=11))
+
 
 class Config:
     DATABASE_URL = os.environ.get("DATABASE_URL")

app/routes/api.py

@@ -1,9 +1,12 @@
-from flask import Blueprint, jsonify, request, session
+from collections import OrderedDict
-from app import SYDNEY_TZ
-from app.auth import login_required
-from app.db import query, query_one
 from datetime import datetime, timezone
 
+from flask import Blueprint, jsonify, request, session
+from app.config import SYDNEY_TZ
+from app.auth import login_required, privacy_guard
+from app.db import query
+from app.utils import calculate_weight_change
+
 bp = Blueprint("api", __name__, url_prefix="/api")
 
 # Distinct hues for up to 12 users; cycles if more
@@ -58,7 +61,6 @@ def progress_over_time():
     """, params)
 
     # Group rows by user
-    from collections import OrderedDict
     users_map = OrderedDict()
     for r in rows:
         uid = r["user_id"]
@@ -90,7 +92,6 @@ def progress_over_time():
         points = entry["data"]
         best_fit = {"slope": 0, "intercept": 0}
         if len(points) >= 2:
-            # Convert dates to day offsets from first point
             base = datetime.strptime(points[0]["date"], "%Y-%m-%d")
             xs = [(datetime.strptime(p["date"], "%Y-%m-%d") - base).days for p in points]
             ys = [p["weight"] for p in points]
@@ -118,14 +119,9 @@ def progress_over_time():
 
 @bp.route("/chart-data/<int:user_id>")
 @login_required
+@privacy_guard
 def chart_data(user_id):
     """Return weight & BMI over time for Chart.js."""
-    # Privacy guard: don't expose private user data to others
-    if user_id != session.get("user_id"):
-        target = query_one("SELECT is_private FROM users WHERE id = %s", (user_id,))
-        if target and target["is_private"]:
-            return jsonify({"labels": [], "weights": [], "bmis": []})
-
     checkins = query(
         """SELECT weight_kg, bmi, checked_in_at
            FROM checkins WHERE user_id = %s
@@ -169,15 +165,10 @@ def comparison():
     for u in users:
         start_w = float(u["starting_weight_kg"] or u["first_weight"] or 0)
         current_w = float(u["current_weight"] or start_w)
-        if start_w > 0:
+        lost, pct = calculate_weight_change(start_w, current_w)
-            lost = start_w - current_w
-            pct = round((lost / start_w) * 100, 1)
-        else:
-            lost = 0
-            pct = 0
         names.append(u["display_name"] or u["username"])
         pct_lost.append(pct)
-        kg_lost.append(round(lost, 1))
+        kg_lost.append(lost)
 
     return jsonify({
         "names": names,
@@ -188,14 +179,9 @@ def comparison():
 
 @bp.route("/weekly-change/<int:user_id>")
 @login_required
+@privacy_guard
 def weekly_change(user_id):
     """Return weekly weight changes for bar chart."""
-    # Privacy guard: don't expose private user data to others
-    if user_id != session.get("user_id"):
-        target = query_one("SELECT is_private FROM users WHERE id = %s", (user_id,))
-        if target and target["is_private"]:
-            return jsonify({"labels": [], "changes": []})
-
     checkins = query(
         """SELECT weight_kg, checked_in_at
            FROM checkins WHERE user_id = %s

app/routes/auth.py

@@ -1,6 +1,7 @@
 from flask import Blueprint, render_template, request, redirect, url_for, session, flash
 from werkzeug.security import generate_password_hash, check_password_hash
-from app.db import query_one, execute_returning, execute
+from app.db import query_one, execute_returning
+from app.utils import parse_profile_fields
 
 bp = Blueprint("auth", __name__)
 
@@ -10,13 +11,7 @@ def signup():
     if request.method == "POST":
         username = request.form.get("username", "").strip()
         password = request.form.get("password", "")
-        display_name = request.form.get("display_name", "").strip()
+        fields = parse_profile_fields(request.form)
-        height_cm = request.form.get("height_cm") or None
-        age = request.form.get("age") or None
-        gender = request.form.get("gender") or None
-        goal_weight_kg = request.form.get("goal_weight_kg") or None
-        starting_weight_kg = request.form.get("starting_weight_kg") or None
-        is_private = request.form.get("is_private") == "on"
 
         # Validation
         if not username or not password:
@@ -38,7 +33,11 @@ def signup():
         user = execute_returning(
             """INSERT INTO users (username, password_hash, display_name, height_cm, age, gender, goal_weight_kg, starting_weight_kg, is_private)
                VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s) RETURNING id""",
-            (username, password_hash, display_name or username, height_cm, age, gender, goal_weight_kg, starting_weight_kg, is_private),
+            (username, password_hash,
+             fields["display_name"] or username,
+             fields["height_cm"], fields["age"], fields["gender"],
+             fields["goal_weight_kg"], fields["starting_weight_kg"],
+             fields["is_private"]),
         )
 
         session["user_id"] = user["id"]

app/routes/checkin.py

@@ -1,57 +1,11 @@
-import math
 from flask import Blueprint, render_template, request, redirect, url_for, flash
 from app.auth import login_required, get_current_user
 from app.db import query, query_one, execute, execute_returning
+from app.utils import calculate_bmi, check_milestones
 
 bp = Blueprint("checkin", __name__)
 
 
-def calculate_bmi(weight_kg, height_cm):
-    """Calculate BMI from weight (kg) and height (cm)."""
-    if not weight_kg or not height_cm or float(height_cm) == 0:
-        return None
-    h_m = float(height_cm) / 100.0
-    return round(float(weight_kg) / (h_m * h_m), 1)
-
-
-def check_milestones(user_id, user):
-    """Check and award any new milestones after a check-in."""
-    checkins = query(
-        "SELECT weight_kg, checked_in_at FROM checkins WHERE user_id = %s ORDER BY checked_in_at ASC",
-        (user_id,),
-    )
-    if not checkins:
-        return
-
-    starting = float(user.get("starting_weight_kg") or checkins[0]["weight_kg"])
-    current = float(checkins[-1]["weight_kg"])
-    total_lost = starting - current
-    count = len(checkins)
-
-    milestone_checks = [
-        ("first_checkin", count >= 1),
-        ("5_checkins", count >= 5),
-        ("10_checkins", count >= 10),
-        ("25_checkins", count >= 25),
-        ("lost_1kg", total_lost >= 1),
-        ("lost_2kg", total_lost >= 2),
-        ("lost_5kg", total_lost >= 5),
-        ("lost_10kg", total_lost >= 10),
-        ("lost_15kg", total_lost >= 15),
-        ("lost_20kg", total_lost >= 20),
-    ]
-
-    for key, achieved in milestone_checks:
-        if achieved:
-            try:
-                execute(
-                    "INSERT INTO milestones (user_id, milestone_key) VALUES (%s, %s) ON CONFLICT DO NOTHING",
-                    (user_id, key),
-                )
-            except Exception:
-                pass
-
-
 @bp.route("/checkin", methods=["GET"])
 @login_required
 def index():
@@ -88,7 +42,6 @@ def create():
         (user["id"], weight_kg, bmi, notes or None),
     )
 
-    # Check milestones
     check_milestones(user["id"], user)
 
     # If HTMX request, return just the new row
@@ -99,6 +52,72 @@ def create():
     return redirect(url_for("checkin.index"))
 
 
+@bp.route("/checkin/<int:checkin_id>/edit", methods=["GET"])
+@login_required
+def edit_form(checkin_id):
+    user = get_current_user()
+    checkin = query_one(
+        "SELECT * FROM checkins WHERE id = %s AND user_id = %s",
+        (checkin_id, user["id"]),
+    )
+    if not checkin:
+        return "", 404
+    return render_template("partials/checkin_edit_row.html", c=checkin, user=user)
+
+
+@bp.route("/checkin/<int:checkin_id>/view", methods=["GET"])
+@login_required
+def view_row(checkin_id):
+    user = get_current_user()
+    checkin = query_one(
+        "SELECT * FROM checkins WHERE id = %s AND user_id = %s",
+        (checkin_id, user["id"]),
+    )
+    if not checkin:
+        return "", 404
+    return render_template("partials/checkin_row.html", c=checkin, user=user)
+
+
+@bp.route("/checkin/<int:checkin_id>", methods=["PUT"])
+@login_required
+def update(checkin_id):
+    user = get_current_user()
+    weight_kg = request.form.get("weight_kg")
+    notes = request.form.get("notes", "").strip()
+
+    checkin = query_one(
+        "SELECT * FROM checkins WHERE id = %s AND user_id = %s",
+        (checkin_id, user["id"]),
+    )
+    if not checkin:
+        return "", 404
+
+    if not weight_kg:
+        flash("Weight is required.", "error")
+        return render_template("partials/checkin_edit_row.html", c=checkin, user=user)
+
+    try:
+        weight_kg = float(weight_kg)
+    except ValueError:
+        flash("Invalid weight value.", "error")
+        return render_template("partials/checkin_edit_row.html", c=checkin, user=user)
+
+    bmi = calculate_bmi(weight_kg, user.get("height_cm"))
+
+    execute(
+        """UPDATE checkins SET weight_kg = %s, bmi = %s, notes = %s
+           WHERE id = %s AND user_id = %s""",
+        (weight_kg, bmi, notes or None, checkin_id, user["id"]),
+    )
+
+    check_milestones(user["id"], user)
+
+    updated = query_one(
+        "SELECT * FROM checkins WHERE id = %s", (checkin_id,)
+    )
+    return render_template("partials/checkin_row.html", c=updated, user=user)
+
+
 @bp.route("/checkin/<int:checkin_id>", methods=["DELETE"])
 @login_required
 def delete(checkin_id):

app/routes/dashboard.py

@@ -1,6 +1,7 @@
 from flask import Blueprint, render_template
 from app.auth import login_required, get_current_user
 from app.db import query, query_one
+from app.utils import calculate_streak, calculate_weight_change
 
 bp = Blueprint("dashboard", __name__)
 
@@ -31,11 +32,11 @@ def index():
     weight_change = None
     weight_change_pct = None
     if latest and first_checkin:
-        start_w = float(first_checkin["weight_kg"])
+        kg_lost, pct_lost = calculate_weight_change(
-        current_w = float(latest["weight_kg"])
+            first_checkin["weight_kg"], latest["weight_kg"]
-        weight_change = round(current_w - start_w, 1)
+        )
-        if start_w > 0:
+        weight_change = round(-kg_lost, 1)       # negative = gained, positive = lost
-            weight_change_pct = round((weight_change / start_w) * 100, 1)
+        weight_change_pct = round(-pct_lost, 1)
 
     # Recent check-ins (last 5)
     recent_checkins = query(
@@ -59,6 +60,9 @@ def index():
         (user["id"],),
     )
 
+    # Streak
+    streak = calculate_streak(user["id"])
+
     return render_template(
         "dashboard.html",
         user=user,
@@ -69,4 +73,5 @@ def index():
         recent_checkins=recent_checkins,
         activity=activity,
         milestones=milestones,
+        streak=streak,
     )

app/routes/leaderboard.py

@@ -1,7 +1,8 @@
 from flask import Blueprint, render_template
 from app.auth import login_required
 from app.db import query, query_one
-from app import SYDNEY_TZ
+from app.config import SYDNEY_TZ
+from app.utils import calculate_streak, calculate_weight_change
 from datetime import timezone
 
 bp = Blueprint("leaderboard", __name__)
@@ -32,13 +33,7 @@ def index():
     for u in users:
         start_w = float(u["starting_weight_kg"] or u["first_weight"] or 0)
         current_w = float(u["current_weight"] or start_w)
-
+        weight_lost, pct_lost = calculate_weight_change(start_w, current_w)
-        if start_w > 0:
-            weight_lost = start_w - current_w
-            pct_lost = round((weight_lost / start_w) * 100, 1)
-        else:
-            weight_lost = 0
-            pct_lost = 0
 
         goal = float(u["goal_weight_kg"]) if u["goal_weight_kg"] else None
         goal_progress = None
@@ -46,11 +41,13 @@ def index():
             total_to_lose = start_w - goal
             goal_progress = min(100, round((weight_lost / total_to_lose) * 100, 1)) if total_to_lose > 0 else 0
 
+        streak = calculate_streak(u["id"])
         ranked.append({
             **u,
-            "weight_lost": round(weight_lost, 1),
+            "weight_lost": weight_lost,
             "pct_lost": pct_lost,
             "goal_progress": goal_progress,
+            "streak": streak["current"],
         })
 
     # Sort by % lost (descending)

app/routes/profile.py

@@ -1,6 +1,7 @@
 from flask import Blueprint, render_template, request, redirect, url_for, flash
 from app.auth import login_required, get_current_user
 from app.db import execute
+from app.utils import parse_profile_fields
 
 bp = Blueprint("profile", __name__)
 
@@ -16,21 +17,17 @@ def index():
 @login_required
 def update():
     user = get_current_user()
-    display_name = request.form.get("display_name", "").strip()
+    fields = parse_profile_fields(request.form)
-    height_cm = request.form.get("height_cm") or None
-    age = request.form.get("age") or None
-    gender = request.form.get("gender") or None
-    goal_weight_kg = request.form.get("goal_weight_kg") or None
-    starting_weight_kg = request.form.get("starting_weight_kg") or None
-    is_private = request.form.get("is_private") == "on"
 
     execute(
         """UPDATE users
            SET display_name = %s, height_cm = %s, age = %s, gender = %s,
                goal_weight_kg = %s, starting_weight_kg = %s, is_private = %s
            WHERE id = %s""",
-        (display_name or user["username"], height_cm, age, gender,
+        (fields["display_name"] or user["username"],
-         goal_weight_kg, starting_weight_kg, is_private, user["id"]),
+         fields["height_cm"], fields["age"], fields["gender"],
+         fields["goal_weight_kg"], fields["starting_weight_kg"],
+         fields["is_private"], user["id"]),
     )
 
     if request.headers.get("HX-Request"):

app/static/css/style.css

@@ -294,6 +294,11 @@ body {
     opacity: 1;
 }
 
+.stat-card-streak::before {
+    background: linear-gradient(135deg, #f59e0b, #ef4444);
+    opacity: 1;
+}
+
 .stat-label {
     font-size: 0.75rem;
     font-weight: 500;
@@ -737,6 +742,42 @@ tr:hover td {
     border-color: rgba(239, 68, 68, 0.2);
 }
 
+.btn-icon-success:hover {
+    color: var(--success) !important;
+    background: var(--success-bg) !important;
+    border-color: rgba(16, 185, 129, 0.2) !important;
+}
+
+/* ========== INLINE EDIT ========== */
+.checkin-actions {
+    display: flex;
+    gap: 0.25rem;
+    align-items: center;
+}
+
+.edit-input {
+    width: 100%;
+    max-width: 120px;
+    padding: 0.35rem 0.6rem;
+    background: var(--bg-input);
+    border: 1px solid var(--border);
+    border-radius: var(--radius-sm);
+    color: var(--text-primary);
+    font-family: inherit;
+    font-size: 0.85rem;
+    transition: all 0.2s ease;
+    outline: none;
+}
+
+.edit-input:focus {
+    border-color: var(--border-focus);
+    box-shadow: 0 0 0 2px var(--accent-glow);
+}
+
+.editing-row td {
+    background: var(--bg-card-hover);
+}
+
 /* ========== EMPTY STATE ========== */
 .empty-state {
     text-align: center;
@@ -933,20 +974,46 @@ tr:hover td {
     }
 
     .container {
-        padding: 1rem;
+        padding: 0.75rem;
     }
 
     .stats-grid {
         grid-template-columns: repeat(2, 1fr);
+        gap: 0.6rem;
+        margin-bottom: 1rem;
+    }
+
+    .stat-card {
+        padding: 0.85rem;
+    }
+
+    .stat-value {
+        font-size: 1.35rem;
+    }
+
+    .stat-label {
+        font-size: 0.65rem;
+        margin-bottom: 0.25rem;
     }
 
     .charts-grid {
         grid-template-columns: 1fr;
+        gap: 0.75rem;
+        margin-bottom: 1rem;
+    }
+
+    .chart-container {
+        height: 220px;
     }
 
     .grid-2,
     .grid-3 {
         grid-template-columns: 1fr;
+        gap: 0.75rem;
+    }
+
+    .card {
+        padding: 1rem;
     }
 
     .form-inline {
@@ -958,12 +1025,16 @@ tr:hover td {
         margin-bottom: 0.75rem;
     }
 
-    .page-header h1 {
+    .page-header {
-        font-size: 1.4rem;
+        margin-bottom: 1rem;
     }
 
-    .stat-value {
+    .page-header h1 {
-        font-size: 1.4rem;
+        font-size: 1.3rem;
+    }
+
+    .page-header p {
+        font-size: 0.8rem;
     }
 
     .auth-card {
@@ -998,10 +1069,27 @@ tr:hover td {
     .filter-group-people {
         min-width: unset;
     }
+
+    .card-header h2 {
+        font-size: 0.9rem;
+    }
+
+    .activity-item {
+        padding: 0.5rem 0;
+    }
 }
 
 @media (max-width: 480px) {
     .stats-grid {
-        grid-template-columns: 1fr;
+        grid-template-columns: repeat(2, 1fr);
+        gap: 0.5rem;
+    }
+
+    .stat-card {
+        padding: 0.7rem;
+    }
+
+    .stat-value {
+        font-size: 1.15rem;
     }
 }

app/templates/dashboard.html

@@ -34,9 +34,11 @@
         <div class="stat-label">Current BMI</div>
         <div class="stat-value">{{ '%.1f' % (latest.bmi | float) if latest and latest.bmi else '—' }}</div>
     </div>
-    <div class="stat-card">
+    <div class="stat-card {{ 'stat-card-streak' if streak.current >= 3 }}">
         <div class="stat-label">Check-ins</div>
         <div class="stat-value">{{ stats.total_checkins if stats else 0 }}</div>
+        <div class="stat-change" style="color: var(--warning);">🔥 {{ streak.current }}-day streak{% if streak.best >
+            streak.current %} · Best: {{ streak.best }}{% endif %}</div>
     </div>
 </div>
 
@@ -101,18 +103,7 @@
             <div class="milestones-grid">
                 {% for m in milestones %}
                 <span class="milestone-badge {{ 'gold' if 'lost' in m.milestone_key else '' }}">
-                    {% if m.milestone_key == 'first_checkin' %}✅ First Check-in
+                    {{ MILESTONE_LABELS.get(m.milestone_key, m.milestone_key) }}
-                    {% elif m.milestone_key == '5_checkins' %}🔥 5 Check-ins
-                    {% elif m.milestone_key == '10_checkins' %}💪 10 Check-ins
-                    {% elif m.milestone_key == '25_checkins' %}🎯 25 Check-ins
-                    {% elif m.milestone_key == 'lost_1kg' %}⭐ 1kg Lost
-                    {% elif m.milestone_key == 'lost_2kg' %}⭐ 2kg Lost
-                    {% elif m.milestone_key == 'lost_5kg' %}🌟 5kg Lost
-                    {% elif m.milestone_key == 'lost_10kg' %}💎 10kg Lost
-                    {% elif m.milestone_key == 'lost_15kg' %}👑 15kg Lost
-                    {% elif m.milestone_key == 'lost_20kg' %}🏆 20kg Lost
-                    {% else %}{{ m.milestone_key }}
-                    {% endif %}
                 </span>
                 {% endfor %}
             </div>

app/templates/leaderboard.html

@@ -56,6 +56,7 @@
                     <th>Lost (%)</th>
                     <th>Goal Progress</th>
                     <th>Check-ins</th>
+                    <th>Streak</th>
                 </tr>
             </thead>
             <tbody>
@@ -96,6 +97,8 @@
                         {% endif %}
                     </td>
                     <td>{{ u.total_checkins }}</td>
+                    <td>{% if u.streak > 0 %}<span style="color: var(--warning);">🔥 {{ u.streak }}d</span>{% else
+                        %}<span style="color: var(--text-muted);">—</span>{% endif %}</td>
                 </tr>
                 {% endfor %}
             </tbody>

app/templates/partials/checkin_edit_row.html

@@ -0,0 +1,19 @@
+<tr id="checkin-{{ c.id }}" class="editing-row">
+    <td>{{ c.checked_in_at | sydney }}</td>
+    <td>
+        <input type="number" name="weight_kg" class="edit-input" step="0.1" value="{{ '%.1f' % (c.weight_kg | float) }}"
+            required autofocus>
+    </td>
+    <td style="color: var(--text-muted); font-size: 0.8rem;">auto</td>
+    <td>
+        <input type="text" name="notes" class="edit-input" placeholder="Notes" value="{{ c.notes or '' }}">
+    </td>
+    <td>
+        <div class="checkin-actions">
+            <button class="btn-icon btn-icon-success" hx-put="/checkin/{{ c.id }}" hx-target="#checkin-{{ c.id }}"
+                hx-swap="outerHTML" hx-include="closest tr" title="Save">✓</button>
+            <button class="btn-icon" hx-get="/checkin/{{ c.id }}/view" hx-target="#checkin-{{ c.id }}"
+                hx-swap="outerHTML" title="Cancel">✕</button>
+        </div>
+    </td>
+</tr>

app/templates/partials/checkin_row.html

@@ -4,7 +4,11 @@
     <td>{{ '%.1f' % (c.bmi | float) if c.bmi else '—' }}</td>
     <td>{{ c.notes or '—' }}</td>
     <td>
+        <div class="checkin-actions">
+            <button class="btn-icon" hx-get="/checkin/{{ c.id }}/edit" hx-target="#checkin-{{ c.id }}"
+                hx-swap="outerHTML" title="Edit">✏️</button>
             <button class="btn-icon" hx-delete="/checkin/{{ c.id }}" hx-target="#checkin-{{ c.id }}" hx-swap="outerHTML"
-            hx-confirm="Delete this check-in?">🗑️</button>
+                hx-confirm="Delete this check-in?" title="Delete">🗑️</button>
+        </div>
     </td>
 </tr>

app/utils.py

@@ -0,0 +1,167 @@
+"""
+Shared business-logic helpers.
+
+Keep route handlers thin — calculation logic lives here.
+"""
+
+from app.db import query, execute
+from app.config import SYDNEY_TZ
+from datetime import datetime, timedelta
+
+
+# ---------------------------------------------------------------------------
+# Milestones — single source of truth for keys, thresholds, and labels
+# ---------------------------------------------------------------------------
+
+MILESTONES = [
+    # (key, check_fn_or_description, emoji + display label)
+    ("first_checkin", "count >= 1", "✅ First Check-in"),
+    ("5_checkins",    "count >= 5", "🔥 5 Check-ins"),
+    ("10_checkins",   "count >= 10", "💪 10 Check-ins"),
+    ("25_checkins",   "count >= 25", "🎯 25 Check-ins"),
+    ("lost_1kg",      "lost >= 1",  "⭐ 1kg Lost"),
+    ("lost_2kg",      "lost >= 2",  "⭐ 2kg Lost"),
+    ("lost_5kg",      "lost >= 5",  "🌟 5kg Lost"),
+    ("lost_10kg",     "lost >= 10", "💎 10kg Lost"),
+    ("lost_15kg",     "lost >= 15", "👑 15kg Lost"),
+    ("lost_20kg",     "lost >= 20", "🏆 20kg Lost"),
+]
+
+# Quick lookup: milestone_key → display label (used in templates)
+MILESTONE_LABELS = {key: label for key, _, label in MILESTONES}
+
+
+# ---------------------------------------------------------------------------
+# Weight calculations
+# ---------------------------------------------------------------------------
+
+def calculate_bmi(weight_kg, height_cm):
+    """Calculate BMI from weight (kg) and height (cm)."""
+    if not weight_kg or not height_cm or float(height_cm) == 0:
+        return None
+    h_m = float(height_cm) / 100.0
+    return round(float(weight_kg) / (h_m * h_m), 1)
+
+
+def calculate_weight_change(start_w, current_w):
+    """Return (kg_lost, pct_lost) from a start and current weight.
+
+    kg_lost is positive when weight decreased.
+    pct_lost is the percentage of start weight that was lost.
+    """
+    start_w = float(start_w or 0)
+    current_w = float(current_w or start_w)
+
+    if start_w > 0:
+        kg_lost = round(start_w - current_w, 1)
+        pct_lost = round((kg_lost / start_w) * 100, 1)
+    else:
+        kg_lost = 0.0
+        pct_lost = 0.0
+
+    return kg_lost, pct_lost
+
+
+# ---------------------------------------------------------------------------
+# Streaks
+# ---------------------------------------------------------------------------
+
+def calculate_streak(user_id):
+    """Calculate current and best consecutive-day check-in streaks."""
+    rows = query(
+        """SELECT DISTINCT (checked_in_at AT TIME ZONE 'UTC' AT TIME ZONE 'Australia/Sydney')::date AS d
+           FROM checkins WHERE user_id = %s ORDER BY d DESC""",
+        (user_id,),
+    )
+    if not rows:
+        return {"current": 0, "best": 0}
+
+    days = [r["d"] for r in rows]
+    today = datetime.now(SYDNEY_TZ).date()
+
+    # Current streak: must include today or yesterday to count
+    current = 0
+    expected = today
+    if days[0] == today or days[0] == today - timedelta(days=1):
+        expected = days[0]
+        for d in days:
+            if d == expected:
+                current += 1
+                expected -= timedelta(days=1)
+            else:
+                break
+
+    # Best streak
+    best = 1
+    run = 1
+    for i in range(1, len(days)):
+        if days[i] == days[i - 1] - timedelta(days=1):
+            run += 1
+            best = max(best, run)
+        else:
+            run = 1
+
+    best = max(best, current)
+    return {"current": current, "best": best}
+
+
+# ---------------------------------------------------------------------------
+# Milestone checker
+# ---------------------------------------------------------------------------
+
+def check_milestones(user_id, user):
+    """Check and award any new milestones after a check-in."""
+    checkins = query(
+        "SELECT weight_kg, checked_in_at FROM checkins WHERE user_id = %s ORDER BY checked_in_at ASC",
+        (user_id,),
+    )
+    if not checkins:
+        return
+
+    starting = float(user.get("starting_weight_kg") or checkins[0]["weight_kg"])
+    current = float(checkins[-1]["weight_kg"])
+    total_lost = starting - current
+    count = len(checkins)
+
+    milestone_checks = [
+        ("first_checkin", count >= 1),
+        ("5_checkins",    count >= 5),
+        ("10_checkins",   count >= 10),
+        ("25_checkins",   count >= 25),
+        ("lost_1kg",      total_lost >= 1),
+        ("lost_2kg",      total_lost >= 2),
+        ("lost_5kg",      total_lost >= 5),
+        ("lost_10kg",     total_lost >= 10),
+        ("lost_15kg",     total_lost >= 15),
+        ("lost_20kg",     total_lost >= 20),
+    ]
+
+    for key, achieved in milestone_checks:
+        if achieved:
+            try:
+                execute(
+                    "INSERT INTO milestones (user_id, milestone_key) VALUES (%s, %s) ON CONFLICT DO NOTHING",
+                    (user_id, key),
+                )
+            except Exception:
+                pass
+
+
+# ---------------------------------------------------------------------------
+# Form helpers
+# ---------------------------------------------------------------------------
+
+def parse_profile_fields(form):
+    """Extract the common profile fields from a request form.
+
+    Returns a dict suitable for both signup and profile-update flows.
+    """
+    return {
+        "display_name": form.get("display_name", "").strip(),
+        "height_cm":    form.get("height_cm") or None,
+        "age":          form.get("age") or None,
+        "gender":       form.get("gender") or None,
+        "goal_weight_kg":     form.get("goal_weight_kg") or None,
+        "starting_weight_kg": form.get("starting_weight_kg") or None,
+        "is_private":   form.get("is_private") == "on",
+    }