diff --git a/README.md b/README.md
index 3326f2c..aef11e0 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ Track workouts, log daily check-ins, explore exercise history, and chat with an
 - **Workouts** — Plan and log workouts with set-level detail (reps, weight, RPE)
 - **Exercises** — Catalog with body-part filtering and history
 - **Check-ins** — Daily weight, calories, steps, sleep tracking
-- **AI Coach** — Chat interface backed by opencode (Big Pickle model, free)
+- **AI Coach** — Persistent chat sidebar (desktop) / full-page chat (mobile) powered by opencode (Big Pickle model, free). Runs as a separate process.
 - **Multi-user** — Login-based, each user has independent data
 - **Calendar view** — See your training history at a glance
 - **NixOS-ready** — Docker-based deploy with provided NixOS module
@@ -24,12 +24,17 @@ uv sync
 uv run python scripts/schema.py
 uv run python scripts/seed.py
 
+# Start the AI coach (in a separate terminal)
+opencode serve --port 4096
+
 # Start the dev server
 uv run uvicorn app.main:app --reload
 ```
 
 Open http://localhost:8000, register a user, and you're ready.
 
+> **Note:** Chat requires `opencode serve` running on port 4096. If `opencode` is not in PATH, use `~/.opencode/bin/opencode serve --port 4096`.
+
 ## Docker
 
 ```bash
diff --git a/app/models/__init__.py b/app/models/__init__.py
index 51a3a35..f91a254 100644
--- a/app/models/__init__.py
+++ b/app/models/__init__.py
@@ -1,7 +1,8 @@
 from app.models.base import Base, engine, async_session
 from app.models.user import User
 from app.models.auth import Session
-from app.models.workout import Phase, Workout, WorkoutSet
+from app.models.workout import Phase, Workout, WorkoutSet, WorkoutSnapshot
 from app.models.exercise import Exercise
 from app.models.checkin import Checkin
 from app.models.chat import ChatMessage
+from app.models.measurement import MeasurementType, Measurement
diff --git a/app/models/measurement.py b/app/models/measurement.py
new file mode 100644
index 0000000..6beb039
--- /dev/null
+++ b/app/models/measurement.py
@@ -0,0 +1,24 @@
+from sqlalchemy import Column, Integer, String, Float, Text, ForeignKey
+
+from app.models.base import Base
+
+
+class MeasurementType(Base):
+    __tablename__ = "measurement_types"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(String(100), nullable=False, unique=True)
+    description = Column(Text)
+    unit = Column(String(50))
+    instructions = Column(Text)
+
+
+class Measurement(Base):
+    __tablename__ = "measurements"
+
+    id = Column(Integer, primary_key=True)
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    measurement_type_id = Column(Integer, ForeignKey("measurement_types.id"), nullable=False)
+    value = Column(Float, nullable=False)
+    date = Column(String(20), nullable=False)
+    notes = Column(Text)
diff --git a/app/models/user.py b/app/models/user.py
index 74ac841..b33e1e8 100644
--- a/app/models/user.py
+++ b/app/models/user.py
@@ -10,10 +10,8 @@ class User(Base):
     username = Column(String(50), unique=True, nullable=False)
     password_hash = Column(String(255), nullable=False)
     display_name = Column(String(100))
-    weight_lb = Column(Float)
-    calorie_goal = Column(Integer)
-    step_goal = Column(Integer)
     medical_notes = Column(Text)
     goals = Column(Text)
     equipment = Column(Text)
+    vital_stats = Column(Text)
     created_at = Column(String(20))
diff --git a/app/models/workout.py b/app/models/workout.py
index 78cfdd0..f178f08 100644
--- a/app/models/workout.py
+++ b/app/models/workout.py
@@ -37,3 +37,14 @@ class WorkoutSet(Base):
     weight = Column(Float)
     rpe = Column(Float)
     notes = Column(Text)
+
+
+class WorkoutSnapshot(Base):
+    __tablename__ = "workout_snapshots"
+
+    id = Column(Integer, primary_key=True)
+    workout_id = Column(Integer, ForeignKey("workouts.id"), nullable=False)
+    changed_by = Column(String(50))
+    reason = Column(Text)
+    sets_snapshot = Column(Text)  # JSON array
+    created_at = Column(String(20))
diff --git a/app/routers/agent_api.py b/app/routers/agent_api.py
index 6241397..39752dc 100644
--- a/app/routers/agent_api.py
+++ b/app/routers/agent_api.py
@@ -1,3 +1,5 @@
+from datetime import datetime, timezone
+import json
 from fastapi import APIRouter, Header, HTTPException, Depends
 from pydantic import BaseModel
 from sqlalchemy import select
@@ -5,7 +7,7 @@ from sqlalchemy import select
 from app.config import AGENT_API_KEY
 from app.models.base import async_session
 from app.models.user import User
-from app.models.workout import Phase, Workout, WorkoutSet
+from app.models.workout import Phase, Workout, WorkoutSet, WorkoutSnapshot
 from app.models.checkin import Checkin
 
 router = APIRouter(prefix="/api/agent", tags=["agent"])
@@ -16,6 +18,39 @@ async def verify_agent(x_api_key: str = Header("")):
         raise HTTPException(status_code=403, detail="invalid api key")
 
 
+async def snapshot_sets(workout_id: int, changed_by: str, reason: str):
+    async with async_session() as session:
+        result = await session.execute(
+            select(WorkoutSet)
+            .where(WorkoutSet.workout_id == workout_id)
+            .order_by(WorkoutSet.exercise, WorkoutSet.set_number)
+        )
+        current_sets = result.scalars().all()
+        if not current_sets:
+            return
+        snapshot_data = [
+            {
+                "id": s.id,
+                "exercise": s.exercise,
+                "set_number": s.set_number,
+                "reps": s.reps,
+                "weight": s.weight,
+                "rpe": s.rpe,
+                "notes": s.notes,
+            }
+            for s in current_sets
+        ]
+        snap = WorkoutSnapshot(
+            workout_id=workout_id,
+            changed_by=changed_by,
+            reason=reason,
+            sets_snapshot=json.dumps(snapshot_data),
+            created_at=datetime.now(timezone.utc).isoformat(),
+        )
+        session.add(snap)
+        await session.commit()
+
+
 class CreatePhaseRequest(BaseModel):
     name: str
     description: str = ""
@@ -39,6 +74,17 @@ class CreateSetRequest(BaseModel):
     weight: float | None = None
     rpe: float | None = None
     notes: str = ""
+    reason: str = ""
+
+
+class UpdateSetRequest(BaseModel):
+    exercise: str | None = None
+    set_number: int | None = None
+    reps: int | None = None
+    weight: float | None = None
+    rpe: float | None = None
+    notes: str | None = None
+    reason: str = ""
 
 
 class CreateCheckinRequest(BaseModel):
@@ -86,6 +132,9 @@ async def agent_add_set(
     body: CreateSetRequest,
     _=Depends(verify_agent),
 ):
+    if body.reason:
+        await snapshot_sets(workout_id, "agent", body.reason)
+
     async with async_session() as session:
         ws = WorkoutSet(
             workout_id=workout_id,
@@ -103,6 +152,71 @@ async def agent_add_set(
     return {"id": ws.id, "exercise": ws.exercise, "set_number": ws.set_number}
 
 
+@router.put("/workouts/{workout_id}/sets/{set_id}")
+async def agent_update_set(
+    workout_id: int,
+    set_id: int,
+    body: UpdateSetRequest,
+    _=Depends(verify_agent),
+):
+    if body.reason:
+        await snapshot_sets(workout_id, "agent", body.reason)
+
+    async with async_session() as session:
+        result = await session.execute(
+            select(WorkoutSet).where(
+                WorkoutSet.id == set_id,
+                WorkoutSet.workout_id == workout_id,
+            )
+        )
+        ws = result.scalar_one_or_none()
+        if not ws:
+            raise HTTPException(status_code=404, detail="set not found")
+
+        if body.exercise is not None:
+            ws.exercise = body.exercise
+        if body.set_number is not None:
+            ws.set_number = body.set_number
+        if body.reps is not None:
+            ws.reps = body.reps
+        if body.weight is not None:
+            ws.weight = body.weight
+        if body.rpe is not None:
+            ws.rpe = body.rpe
+        if body.notes is not None:
+            ws.notes = body.notes
+        await session.commit()
+
+    return {"id": ws.id, "exercise": ws.exercise, "set_number": ws.set_number}
+
+
+@router.delete("/workouts/{workout_id}/sets/{set_id}")
+async def agent_delete_set(
+    workout_id: int,
+    set_id: int,
+    reason: str = "",
+    _=Depends(verify_agent),
+):
+    if reason:
+        await snapshot_sets(workout_id, "agent", reason)
+
+    async with async_session() as session:
+        result = await session.execute(
+            select(WorkoutSet).where(
+                WorkoutSet.id == set_id,
+                WorkoutSet.workout_id == workout_id,
+            )
+        )
+        ws = result.scalar_one_or_none()
+        if not ws:
+            raise HTTPException(status_code=404, detail="set not found")
+
+        await session.delete(ws)
+        await session.commit()
+
+    return {"deleted": set_id}
+
+
 @router.put("/workouts/{workout_id}/complete")
 async def agent_complete_workout(
     workout_id: int,
diff --git a/app/routers/auth.py b/app/routers/auth.py
index b122af3..38c0c4c 100644
--- a/app/routers/auth.py
+++ b/app/routers/auth.py
@@ -6,6 +6,7 @@ from sqlalchemy import select
 
 from app.models.base import async_session
 from app.models.user import User
+from app.models.measurement import Measurement, MeasurementType
 from app.auth import hash_password, verify_password, create_session
 
 router = APIRouter()
@@ -45,6 +46,11 @@ async def register(
     username: str = Form(),
     password: str = Form(),
     display_name: str = Form(default=""),
+    initial_weight: float = Form(default=None),
+    vital_stats: str = Form(default=""),
+    medical_notes: str = Form(default=""),
+    goals: str = Form(default=""),
+    equipment: str = Form(default=""),
 ):
     async with async_session() as session:
         result = await session.execute(select(User).where(User.username == username))
@@ -57,14 +63,33 @@ async def register(
             username=username,
             password_hash=hash_password(password),
             display_name=display_name or username,
+            vital_stats=vital_stats,
+            medical_notes=medical_notes,
+            goals=goals,
+            equipment=equipment,
             created_at=datetime.now(timezone.utc).isoformat(),
         )
         session.add(user)
         await session.commit()
         await session.refresh(user)
+
+        if initial_weight is not None:
+            result = await session.execute(
+                select(MeasurementType).where(MeasurementType.name == "Weight")
+            )
+            wt = result.scalar_one_or_none()
+            if wt:
+                session.add(Measurement(
+                    user_id=user.id,
+                    measurement_type_id=wt.id,
+                    value=initial_weight,
+                    date=datetime.now(timezone.utc).strftime("%Y-%m-%d"),
+                ))
+                await session.commit()
+
         token = await create_session(user.id)
 
-    resp = RedirectResponse(url="/dashboard", status_code=303)
+    resp = RedirectResponse(url="/chat?first=1", status_code=303)
     resp.set_cookie(key="session_token", value=token, httponly=True, max_age=86400 * 30)
     return resp
 
diff --git a/app/routers/chat.py b/app/routers/chat.py
index 0dbf510..b7436ee 100644
--- a/app/routers/chat.py
+++ b/app/routers/chat.py
@@ -1,7 +1,7 @@
 from datetime import datetime, timezone
 import uuid
 from fastapi import APIRouter, Request, Depends, Form
-from fastapi.responses import HTMLResponse, StreamingResponse
+from fastapi.responses import HTMLResponse, StreamingResponse, JSONResponse
 from fastapi.templating import Jinja2Templates
 from sqlalchemy import select, desc
 
@@ -10,15 +10,46 @@ from app.models.user import User
 from app.models.chat import ChatMessage
 from app.models.workout import Workout
 from app.models.checkin import Checkin
+from app.models.measurement import Measurement, MeasurementType
 from app.auth import get_current_user
 from app.services.opencode_proxy import query_opencode
 
 router = APIRouter()
 templates = Jinja2Templates(directory="app/templates")
 
+ONBOARDING_PROMPT = (
+    "I am a new user and this is the first interaction with this application. "
+    "Please review my goals, equipment, medical history, and stats (all in your context). "
+    "Create a high-level training plan that you can use to make weekly plans and daily workouts. "
+    "Ask for more clarity whenever you need it. "
+    "When the workout planning is ready for me to begin, prompt me to switch to the Workouts or Dashboard tab."
+)
+
+
+@router.get("/api/chat/messages")
+async def get_chat_messages(request: Request, user: User = Depends(get_current_user)):
+    session_id = request.cookies.get("chat_session_id")
+    if not session_id:
+        return JSONResponse([])
+    async with async_session() as session:
+        result = await session.execute(
+            select(ChatMessage)
+            .where(
+                ChatMessage.user_id == user.id,
+                ChatMessage.session_id == session_id,
+            )
+            .order_by(desc(ChatMessage.created_at))
+            .limit(15)
+        )
+        rows = result.scalars().all()
+        rows = list(reversed(rows))
+    return JSONResponse([
+        {"role": m.role, "content": m.content, "created_at": m.created_at} for m in rows
+    ])
+
 
 @router.get("/chat", response_class=HTMLResponse)
-async def chat_page(request: Request, user: User = Depends(get_current_user)):
+async def chat_page(request: Request, user: User = Depends(get_current_user), first: int = 0):
     session_id = request.cookies.get("chat_session_id")
     if not session_id:
         session_id = str(uuid.uuid4())
@@ -38,6 +69,8 @@ async def chat_page(request: Request, user: User = Depends(get_current_user)):
         "user": user,
         "messages": messages,
         "session_id": session_id,
+        "first": first,
+        "onboarding_prompt": ONBOARDING_PROMPT,
     })
     resp.set_cookie(key="chat_session_id", value=session_id, httponly=True, max_age=86400 * 30)
     return resp
@@ -68,6 +101,18 @@ async def chat_send(
         )
         recent_checkins = result.scalars().all()
 
+        result = await session.execute(
+            select(Measurement)
+            .join(MeasurementType, Measurement.measurement_type_id == MeasurementType.id)
+            .where(
+                Measurement.user_id == user.id,
+                MeasurementType.name == "Weight",
+            )
+            .order_by(desc(Measurement.date))
+            .limit(1)
+        )
+        latest_weight = result.scalar_one_or_none()
+
     workout_lines = []
     for w in recent_workouts:
         workout_lines.append(f"  {w.date} — {w.name} ({w.status})")
@@ -86,14 +131,15 @@ async def chat_send(
             parts.append(f"sleep={c.sleep_hours}h")
         checkin_lines.append(f"  {c.date} — {' | '.join(parts)}")
 
+    weight_str = f"{latest_weight.value} lb" if latest_weight else "Not recorded"
+
     user_context = (
         f"Username: {user.username}. "
-        f"Weight: {user.weight_lb} lb. "
+        f"Weight: {weight_str}. "
         f"Goals: {user.goals or 'Not specified'}. "
         f"Equipment: {user.equipment or 'Not specified'}. "
         f"Medical: {user.medical_notes or 'None'}. "
-        f"Calorie goal: {user.calorie_goal or 'Not set'}. "
-        f"Step goal: {user.step_goal or 'Not set'}. "
+        f"Vital stats: {user.vital_stats or 'Not specified'}. "
     )
     if recent_workouts:
         user_context += "Recent workouts:\n" + "\n".join(workout_lines) + ". "
diff --git a/app/routers/dashboard.py b/app/routers/dashboard.py
index 215b5ce..7a4d5c0 100644
--- a/app/routers/dashboard.py
+++ b/app/routers/dashboard.py
@@ -8,6 +8,7 @@ from app.models.base import async_session
 from app.models.user import User
 from app.models.workout import Phase, Workout
 from app.models.checkin import Checkin
+from app.models.measurement import Measurement, MeasurementType
 from app.auth import get_current_user
 
 router = APIRouter()
@@ -64,6 +65,18 @@ async def dashboard(request: Request, user: User = Depends(get_current_user)):
         )
         this_week = result.scalars().all()
 
+        result = await session.execute(
+            select(Measurement)
+            .join(MeasurementType, Measurement.measurement_type_id == MeasurementType.id)
+            .where(
+                Measurement.user_id == user.id,
+                MeasurementType.name == "Weight",
+            )
+            .order_by(desc(Measurement.date))
+            .limit(1)
+        )
+        latest_weight = result.scalar_one_or_none()
+
     return templates.TemplateResponse(request, "dashboard.html", {
         "user": user,
         "recent_workouts": recent_workouts,
@@ -72,4 +85,5 @@ async def dashboard(request: Request, user: User = Depends(get_current_user)):
         "this_week": this_week,
         "week_start": week_start,
         "week_end": week_end,
+        "latest_weight": latest_weight.value if latest_weight else None,
     })
diff --git a/app/routers/profile.py b/app/routers/profile.py
index 677d4bd..2954ea4 100644
--- a/app/routers/profile.py
+++ b/app/routers/profile.py
@@ -22,9 +22,7 @@ async def update_profile(
     request: Request,
     user: User = Depends(get_current_user),
     display_name: str = Form(default=None),
-    weight_lb: float = Form(default=None),
-    calorie_goal: int = Form(default=None),
-    step_goal: int = Form(default=None),
+    vital_stats: str = Form(default=""),
     medical_notes: str = Form(default=""),
     goals: str = Form(default=""),
     equipment: str = Form(default=""),
@@ -33,12 +31,7 @@ async def update_profile(
         session.add(user)
         if display_name is not None:
             user.display_name = display_name
-        if weight_lb is not None:
-            user.weight_lb = weight_lb
-        if calorie_goal is not None:
-            user.calorie_goal = calorie_goal
-        if step_goal is not None:
-            user.step_goal = step_goal
+        user.vital_stats = vital_stats
         user.medical_notes = medical_notes
         user.goals = goals
         user.equipment = equipment
diff --git a/app/routers/workouts.py b/app/routers/workouts.py
index 17c5ead..663cb1c 100644
--- a/app/routers/workouts.py
+++ b/app/routers/workouts.py
@@ -142,6 +142,7 @@ async def add_set(
 
 @router.post("/workouts/{workout_id}/complete")
 async def complete_workout(
+    request: Request,
     workout_id: int,
     user: User = Depends(get_current_user),
 ):
@@ -157,4 +158,24 @@ async def complete_workout(
             workout.status = "complete"
             await session.commit()
 
-    return RedirectResponse(url=f"/workouts/{workout_id}", status_code=303)
+        if not workout:
+            return RedirectResponse(url="/workouts", status_code=303)
+
+        result = await session.execute(
+            select(WorkoutSet)
+            .where(WorkoutSet.workout_id == workout_id)
+            .order_by(WorkoutSet.exercise, WorkoutSet.set_number)
+        )
+        sets = result.scalars().all()
+
+        phase = None
+        if workout.phase_id:
+            result = await session.execute(select(Phase).where(Phase.id == workout.phase_id))
+            phase = result.scalar_one_or_none()
+
+    return templates.TemplateResponse(request, "workout_detail.html", {
+        "user": user,
+        "workout": workout,
+        "sets": sets,
+        "phase": phase,
+    })
diff --git a/app/static/chat-sidebar.js b/app/static/chat-sidebar.js
new file mode 100644
index 0000000..f3606f2
--- /dev/null
+++ b/app/static/chat-sidebar.js
@@ -0,0 +1,113 @@
+(function() {
+    const sidebar = document.getElementById('chat-sidebar');
+    if (!sidebar) return;
+
+    const messagesEl = document.getElementById('chat-sidebar-messages');
+    const form = document.getElementById('chat-sidebar-form');
+    const input = document.getElementById('chat-sidebar-input');
+    const status = document.getElementById('chat-sidebar-status');
+
+    function setStatus(msg, isError) {
+        if (status) {
+            status.textContent = msg;
+            status.style.color = isError ? 'var(--del-color, #b33)' : 'var(--muted-color, #888)';
+        }
+    }
+
+    function appendMessage(role, content) {
+        const div = document.createElement('div');
+        div.className = 'chat-message ' + role;
+        div.innerHTML = '<p>' + content + '</p>';
+        messagesEl.appendChild(div);
+        messagesEl.scrollTop = messagesEl.scrollHeight;
+    }
+
+    function removeLoading() {
+        const ld = messagesEl.querySelector('.chat-sidebar-loading');
+        if (ld) ld.remove();
+    }
+
+    async function loadMessages() {
+        try {
+            const resp = await fetch('/api/chat/messages');
+            if (!resp.ok) return;
+            const data = await resp.json();
+            removeLoading();
+            for (const m of data) {
+                appendMessage(m.role, m.content);
+            }
+        } catch (e) {
+            removeLoading();
+            messagesEl.innerHTML = '<p class="chat-sidebar-loading">Could not load messages.</p>';
+        }
+    }
+
+    async function sendMessage(event) {
+        event.preventDefault();
+        const text = input.value.trim();
+        if (!text) return;
+
+        removeLoading();
+        appendMessage('user', text);
+        input.value = '';
+        input.disabled = true;
+        setStatus('Waiting...');
+
+        const assistantDiv = document.createElement('div');
+        assistantDiv.className = 'chat-message assistant';
+        assistantDiv.innerHTML = '<p><em>Thinking...</em></p>';
+        messagesEl.appendChild(assistantDiv);
+
+        try {
+            const formData = new FormData();
+            formData.append('message', text);
+
+            const response = await fetch('/chat', { method: 'POST', body: formData });
+            if (!response.ok) throw new Error('Server returned ' + response.status);
+
+            const reader = response.body.getReader();
+            const decoder = new TextDecoder();
+            const p = assistantDiv.querySelector('p');
+            p.innerHTML = '';
+
+            let buffer = '';
+            while (true) {
+                const { done, value } = await reader.read();
+                if (done) break;
+                buffer += decoder.decode(value, { stream: true });
+                const lines = buffer.split('\n');
+                buffer = lines.pop() || '';
+                for (const line of lines) {
+                    if (line.startsWith('data: ')) {
+                        p.innerHTML += line.slice(6);
+                    }
+                }
+                messagesEl.scrollTop = messagesEl.scrollHeight;
+            }
+
+            if (!p.innerHTML.trim()) {
+                p.innerHTML = '<em>No response.</em>';
+            }
+
+            setStatus('');
+        } catch (err) {
+            assistantDiv.querySelector('p').innerHTML = '<em>Error.</em>';
+            setStatus('Connection error. Is opencode serve running?', true);
+        }
+
+        input.disabled = false;
+        input.focus();
+    }
+
+    if (form) form.addEventListener('submit', sendMessage);
+    if (input) {
+        input.addEventListener('keydown', function(e) {
+            if (e.key === 'Enter' && !e.shiftKey) {
+                e.preventDefault();
+                form.dispatchEvent(new Event('submit'));
+            }
+        });
+    }
+
+    loadMessages();
+})();
\ No newline at end of file
diff --git a/app/static/style.css b/app/static/style.css
index d097da1..3709557 100644
--- a/app/static/style.css
+++ b/app/static/style.css
@@ -34,26 +34,6 @@
     background: var(--card-sectionning-background-color);
 }
 
-.chat-input {
-    display: flex;
-    flex-direction: column;
-    gap: 0.5rem;
-}
-
-.chat-input textarea {
-    width: 100%;
-    resize: vertical;
-    min-height: 2.5rem;
-    box-sizing: border-box;
-}
-
-.chat-input button {
-    width: auto;
-    align-self: flex-end;
-    padding: 0.25rem 1rem;
-    font-size: 0.9rem;
-}
-
 .chat-status {
     margin-top: 0.25rem;
     font-size: 0.85rem;
@@ -62,3 +42,91 @@
 .nav-link.active {
     font-weight: bold;
 }
+
+/* App layout with sidebar */
+.app-layout {
+    display: flex;
+    gap: 1rem;
+    max-width: var(--pico-fluid-max-width, 1200px);
+    margin: 0 auto;
+    padding: 0 var(--pico-spacing, 1rem);
+}
+
+#main-content {
+    flex: 1;
+    min-width: 0;
+}
+
+#chat-sidebar {
+    width: 360px;
+    flex-shrink: 0;
+    position: sticky;
+    top: 0;
+    height: calc(100vh - 4rem);
+    overflow-y: auto;
+    border-left: 1px solid var(--muted-border-color, #ccc);
+    padding-left: 1rem;
+}
+
+.app-layout.no-sidebar #chat-sidebar {
+    display: none;
+}
+
+/* Sidebar chat components */
+.chat-sidebar-header {
+    padding: 0.5rem 0;
+    border-bottom: 1px solid var(--muted-border-color, #ccc);
+    margin-bottom: 0.5rem;
+}
+
+.chat-sidebar-messages {
+    max-height: calc(100vh - 14rem);
+    overflow-y: auto;
+    margin-bottom: 0.5rem;
+}
+
+.chat-sidebar-messages .chat-message {
+    padding: 0.4rem 0.6rem;
+    margin-bottom: 0.4rem;
+    font-size: 0.9rem;
+}
+
+.chat-sidebar-messages .chat-message p {
+    margin: 0;
+}
+
+.chat-sidebar-loading {
+    color: var(--muted-color, #888);
+    text-align: center;
+    font-size: 0.85rem;
+}
+
+.chat-sidebar-form {
+    display: flex;
+    gap: 0.3rem;
+    align-items: flex-end;
+}
+
+.chat-sidebar-form textarea {
+    flex: 1;
+    resize: none;
+    min-height: 2rem;
+    font-size: 0.9rem;
+    padding: 0.3rem;
+}
+
+.chat-sidebar-form button {
+    width: auto;
+    padding: 0.2rem 0.8rem;
+    font-size: 0.85rem;
+    margin: 0;
+}
+
+@media (max-width: 767px) {
+    #chat-sidebar {
+        display: none;
+    }
+    .app-layout {
+        padding: 0;
+    }
+}
\ No newline at end of file
diff --git a/app/templates/base.html b/app/templates/base.html
index 47f6b67..1eaad0b 100644
--- a/app/templates/base.html
+++ b/app/templates/base.html
@@ -6,13 +6,15 @@
     <title>{% block title %}Fitness{% endblock %}</title>
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@picocss/pico@2/css/pico.min.css">
     <link rel="stylesheet" href="/static/style.css">
+    <script src="https://unpkg.com/htmx.org@2"></script>
+    <script src="/static/chat-sidebar.js" defer></script>
 </head>
 <body>
     <nav class="container-fluid">
         <ul>
             <li><strong><a href="/dashboard" class="contrast">Fitness</a></strong></li>
         </ul>
-        <ul>
+        <ul hx-boost="true" hx-target="#main-content" hx-select="#main-content" hx-swap="innerHTML" hx-push-url="true">
             <li><a href="/dashboard">Dashboard</a></li>
             <li><a href="/plan">Plan</a></li>
             <li><a href="/workouts">Workouts</a></li>
@@ -20,11 +22,18 @@
             <li><a href="/checkins">Check-ins</a></li>
             <li><a href="/chat">Chat</a></li>
             <li><a href="/profile">Profile</a></li>
-            <li><a href="/logout">Logout</a></li>
+            <li><a href="/logout" hx-boost="false">Logout</a></li>
         </ul>
     </nav>
-    <main class="container">
-        {% block content %}{% endblock %}
-    </main>
+    <div class="app-layout {% if hide_sidebar %}no-sidebar{% endif %}">
+        <main id="main-content">
+            {% block content %}{% endblock %}
+        </main>
+        <aside id="chat-sidebar">
+            {% if not hide_sidebar %}
+            {% include "chat_sidebar.html" %}
+            {% endif %}
+        </aside>
+    </div>
 </body>
-</html>
+</html>
\ No newline at end of file
diff --git a/app/templates/chat.html b/app/templates/chat.html
index 6f89a38..0e343e9 100644
--- a/app/templates/chat.html
+++ b/app/templates/chat.html
@@ -1,5 +1,6 @@
 {% extends "base.html" %}
 {% block title %}AI Coach{% endblock %}
+{% set hide_sidebar = True %}
 {% block content %}
 <h1>AI Coach</h1>
 
@@ -12,7 +13,8 @@
     {% endfor %}
 </div>
 
-<form class="chat-input" id="chat-form" onsubmit="sendMessage(event)">
+<form class="chat-input" id="chat-form" onsubmit="sendMessage(event)"
+      data-first="{{ first }}" data-onboarding="{{ onboarding_prompt|e }}">
     <textarea id="chat-input" placeholder="Ask your coach..." rows="3" required autocomplete="off"></textarea>
     <button type="submit" id="chat-send-btn">Send</button>
 </form>
@@ -25,6 +27,9 @@ const chatForm = document.getElementById('chat-form');
 const chatSendBtn = document.getElementById('chat-send-btn');
 const chatStatus = document.getElementById('chat-status');
 
+const IS_FIRST = chatForm.dataset.first === '1';
+const ONBOARDING_PROMPT = chatForm.dataset.onboarding;
+
 chatInput.addEventListener('keydown', function(e) {
     if (e.key === 'Enter' && !e.shiftKey) {
         e.preventDefault();
@@ -106,5 +111,10 @@ async function sendMessage(event) {
         chatSendBtn.disabled = false;
     }
 }
+
+if (IS_FIRST && ONBOARDING_PROMPT) {
+    chatInput.value = ONBOARDING_PROMPT;
+    chatForm.dispatchEvent(new Event('submit'));
+}
 </script>
 {% endblock %}
diff --git a/app/templates/chat_sidebar.html b/app/templates/chat_sidebar.html
new file mode 100644
index 0000000..8b11dce
--- /dev/null
+++ b/app/templates/chat_sidebar.html
@@ -0,0 +1,11 @@
+<div class="chat-sidebar-header">
+    <strong>AI Coach</strong>
+</div>
+<div id="chat-sidebar-messages" class="chat-sidebar-messages">
+    <p class="chat-sidebar-loading">Loading...</p>
+</div>
+<form id="chat-sidebar-form" class="chat-sidebar-form">
+    <textarea id="chat-sidebar-input" rows="2" placeholder="Ask your coach..." autocomplete="off"></textarea>
+    <button type="submit">Send</button>
+</form>
+<p id="chat-sidebar-status" class="chat-status"></p>
\ No newline at end of file
diff --git a/app/templates/dashboard.html b/app/templates/dashboard.html
index 0c331f9..f976d84 100644
--- a/app/templates/dashboard.html
+++ b/app/templates/dashboard.html
@@ -6,15 +6,7 @@
 <div class="grid">
     <article>
         <h3>Weight</h3>
-        <p style="font-size: 2rem;">{{ user.weight_lb or '—' }} lb</p>
-    </article>
-    <article>
-        <h3>Calorie Goal</h3>
-        <p style="font-size: 2rem;">{{ user.calorie_goal or '—' }}</p>
-    </article>
-    <article>
-        <h3>Step Goal</h3>
-        <p style="font-size: 2rem;">{{ user.step_goal or '—' }}</p>
+        <p style="font-size: 2rem;">{{ latest_weight or '—' }} lb</p>
     </article>
 </div>
 
diff --git a/app/templates/login.html b/app/templates/login.html
index 754c0b2..76254eb 100644
--- a/app/templates/login.html
+++ b/app/templates/login.html
@@ -1,5 +1,6 @@
 {% extends "base.html" %}
 {% block title %}Login{% endblock %}
+{% set hide_sidebar = True %}
 {% block content %}
 <article style="max-width: 400px; margin: 4rem auto;">
     <h1>Login</h1>
diff --git a/app/templates/profile.html b/app/templates/profile.html
index 457f346..7a948c3 100644
--- a/app/templates/profile.html
+++ b/app/templates/profile.html
@@ -7,20 +7,11 @@
         Display Name
         <input type="text" name="display_name" value="{{ user.display_name or '' }}">
     </label>
-    <div class="grid">
-        <label>
-        Weight (lb)
-        <input type="number" name="weight_lb" step="0.1" value="{{ user.weight_lb or '' }}">
-        </label>
-        <label>
-            Calorie Goal
-            <input type="number" name="calorie_goal" value="{{ user.calorie_goal or '' }}">
-        </label>
-        <label>
-            Step Goal
-            <input type="number" name="step_goal" value="{{ user.step_goal or '' }}">
-        </label>
-    </div>
+    <label>
+        Vital Stats
+        <textarea name="vital_stats" rows="5" placeholder="Birth Date:&#10;Height:&#10;Gender:&#10;Other:">{{ user.vital_stats or '' }}</textarea>
+    </label>
+    <small>Free-form stats passed to your AI coach.</small>
     <label>
         Medical Notes
         <textarea name="medical_notes" rows="4">{{ user.medical_notes or '' }}</textarea>
diff --git a/app/templates/register.html b/app/templates/register.html
index 209c5d1..bef416b 100644
--- a/app/templates/register.html
+++ b/app/templates/register.html
@@ -1,26 +1,54 @@
 {% extends "base.html" %}
 {% block title %}Register{% endblock %}
+{% set hide_sidebar = True %}
 {% block content %}
-<article style="max-width: 400px; margin: 4rem auto;">
+<article style="max-width: 600px; margin: 4rem auto;">
     <h1>Register</h1>
     {% if error %}
     <p style="color: var(--red)">{{ error }}</p>
     {% endif %}
     <form method="post" action="/register">
+        <h3>Account</h3>
         <label>
             Username
             <input type="text" name="username" required autocomplete="username">
         </label>
+        <label>
+            Password
+            <input type="password" name="password" required autocomplete="new-password">
+        </label>
+
+        <h3>Profile</h3>
         <label>
             Display Name
             <input type="text" name="display_name" autocomplete="name">
         </label>
         <label>
-            Password
-            <input type="password" name="password" required autocomplete="new-password">
+            Initial Weight (lb)
+            <input type="number" name="initial_weight" step="0.1">
         </label>
+        <label>
+            Vital Stats
+            <textarea name="vital_stats" rows="5" placeholder="Birth Date:&#10;Height:&#10;Gender:&#10;Other:"></textarea>
+        </label>
+        <small>Free-form stats passed to your AI coach. Fill in what you want.</small>
+
+        <h3>Background</h3>
+        <label>
+            Medical Notes
+            <textarea name="medical_notes" rows="3" placeholder="Injuries, conditions, limitations..."></textarea>
+        </label>
+        <label>
+            Goals
+            <textarea name="goals" rows="3" placeholder="Weight control, strength, endurance..."></textarea>
+        </label>
+        <label>
+            Equipment
+            <textarea name="equipment" rows="3" placeholder="Dumbbells, bench, bands, pull-up bar..."></textarea>
+        </label>
+
         <button type="submit">Register</button>
     </form>
     <p>Already have an account? <a href="/login">Login</a></p>
 </article>
-{% endblock %}
+{% endblock %}
\ No newline at end of file
diff --git a/app/templates/workout_detail.html b/app/templates/workout_detail.html
index dd13455..a91e17a 100644
--- a/app/templates/workout_detail.html
+++ b/app/templates/workout_detail.html
@@ -40,44 +40,13 @@
 <p>No sets logged yet.</p>
 {% endif %}
 
-<h3>Add Set</h3>
-<form method="post" action="/workouts/{{ workout.id }}/add-set" class="set-row">
-    <label>
-        Exercise
-        <input type="text" name="exercise" required list="exercise-list">
-        <datalist id="exercise-list">
-            {% for s in sets %}
-            <option value="{{ s.exercise }}">
-            {% endfor %}
-        </datalist>
-    </label>
-    <label>
-        Set #
-        <input type="number" name="set_number" required min="1">
-    </label>
-    <label>
-        Reps
-        <input type="number" name="reps" min="1">
-    </label>
-    <label>
-        Weight
-        <input type="number" name="weight" step="0.5">
-    </label>
-    <label>
-        RPE
-        <input type="number" name="rpe" min="1" max="10" step="0.5">
-    </label>
-    <label>
-        Notes
-        <input type="text" name="notes">
-    </label>
-    <button type="submit">Add</button>
-</form>
-
 {% if workout.status == "plan" %}
-<form method="post" action="/workouts/{{ workout.id }}/complete">
-    <button type="submit" class="secondary">Mark Complete</button>
-</form>
+<button type="submit" class="secondary"
+    hx-post="/workouts/{{ workout.id }}/complete"
+    hx-target="#main-content"
+    hx-select="#main-content"
+    hx-swap="innerHTML"
+    hx-push-url="/workouts/{{ workout.id }}">Mark Complete</button>
 {% endif %}
 
 <a href="/workouts">Back to Workouts</a>
diff --git a/fitness.db b/fitness.db
new file mode 100644
index 0000000..e69de29
diff --git a/opencode/fitness-trainer.md b/opencode/fitness-trainer.md
index a653beb..f7056fc 100644
--- a/opencode/fitness-trainer.md
+++ b/opencode/fitness-trainer.md
@@ -50,6 +50,15 @@ honest. You are their single point of contact for training chat.
   Mid-range movements only (e.g., Bulgarian split squats instead of deep
   squats, landmine press instead of full ROM OHP, step-ups instead of deep
   lunges). Apply this to squat, hinge, push, pull, and core movements alike.
+- **Chat sidebar is always available.** Your chat interface appears on the
+  right side of the app on desktop. The user can message you from any page
+  (dashboard, workout detail, etc.). Be responsive to mid-workout questions
+  and adjustments.
+- **Post-workout follow-up.** After a workout is marked complete, proactively
+  ask how it went and whether the user should rest or train next. Suggest
+  adjustments to the weekly plan and create the next workout in the database.
+  The sidebar context includes the user's recent workout status, so check
+  whether the most recent workout was just completed.
 
 ## API — Creating Workouts and Check-ins
 
@@ -77,7 +86,19 @@ Body: { username, name, date, phase_id?, notes? }
 **Add a set to a workout:**
 ```
 POST /api/agent/workouts/{id}/sets
-Body: { exercise, set_number, reps?, weight?, rpe?, notes? }
+Body: { exercise, set_number, reps?, weight?, rpe?, notes?, reason? }
+```
+Include `reason` when making changes mid-workout — it triggers a snapshot.
+
+**Update a set (mid-workout adjustments):**
+```
+PUT /api/agent/workouts/{id}/sets/{set_id}
+Body: { exercise?, set_number?, reps?, weight?, rpe?, notes?, reason? }
+```
+
+**Delete a set:**
+```
+DELETE /api/agent/workouts/{id}/sets/{set_id}?reason=...
 ```
 
 **Mark a workout complete:**
@@ -110,6 +131,10 @@ Body: { name, description?, start_date?, end_date?, notes? }
 
 Always use the username from the context provided with each message.
 
+Whenever you modify a workout's sets (add, update, delete), include a
+`reason` field describing why. This triggers a snapshot of the sets before
+the change, preserving the previous state for review.
+
 ## Managing the Training Plan
 
 You maintain a training plan broken into phases. The plan lives in the
diff --git a/scripts/seed.py b/scripts/seed.py
index 8683952..755722f 100644
--- a/scripts/seed.py
+++ b/scripts/seed.py
@@ -1,5 +1,5 @@
 """
-Seed the database with initial data (exercises, phases).
+Seed the database with initial data (exercises, phases, measurement types).
 Run with: python scripts/seed.py
 """
 import asyncio
@@ -12,10 +12,10 @@ from sqlalchemy import select
 from app.models import async_session
 from app.models.exercise import Exercise
 from app.models.workout import Phase
+from app.models.measurement import MeasurementType
 
 
 EXERCISES = [
-    # Push
     ("Bench Press", "chest", "barbell, bench"),
     ("Incline Dumbbell Press", "chest", "dumbbell, bench"),
     ("Overhead Press", "shoulders", "barbell"),
@@ -24,7 +24,6 @@ EXERCISES = [
     ("Lateral Raise", "shoulders", "dumbbell"),
     ("Tricep Pushdown", "triceps", "cable, bands"),
     ("Dip", "chest", "dip station"),
-    # Pull
     ("Barbell Row", "back", "barbell"),
     ("Dumbbell Row", "back", "dumbbell, bench"),
     ("Lat Pulldown", "back", "cable, bands"),
@@ -32,7 +31,6 @@ EXERCISES = [
     ("Face Pull", "shoulders", "cable, bands"),
     ("YTW", "shoulders", "dumbbell, bands"),
     ("Bicep Curl", "biceps", "dumbbell"),
-    # Legs
     ("Barbell Squat", "quadriceps", "barbell, squat rack"),
     ("Goblet Squat", "quadriceps", "dumbbell, kettlebell"),
     ("Bulgarian Split Squat", "quadriceps", "dumbbell, bench"),
@@ -42,19 +40,16 @@ EXERCISES = [
     ("Leg Curl", "hamstrings", "cable, bands"),
     ("Calf Raise", "calves", "barbell, dumbbell"),
     ("Deadlift", "back", "barbell"),
-    # Core
     ("Dead Bug", "core", "bodyweight"),
     ("Pallof Press", "core", "cable, bands"),
     ("Plank", "core", "bodyweight"),
     ("Ab Wheel Rollout", "core", "ab wheel"),
     ("Russian Twist", "core", "bodyweight, dumbbell"),
     ("Hanging Knee Raise", "core", "pull-up bar"),
-    # Cardio
     ("BikeErg", "cardio", "bikeerg"),
     ("RowErg", "cardio", "rowerg"),
     ("Jump Rope", "cardio", "jump rope"),
     ("Walking", "cardio", "bodyweight"),
-    # Accessory
     ("Farmer's Carry", "grip", "dumbbell, kettlebell"),
     ("Bird Dog", "core", "bodyweight"),
     ("Glute Bridge", "glutes", "bodyweight"),
@@ -69,6 +64,17 @@ PHASES = [
     ("Strength Building", "Phase 3: Normal training. RPE 8-9, full ROM.", None, None, "Weeks 8+"),
 ]
 
+MEASUREMENT_TYPES = [
+    ("Weight", "Body weight measurement", "lb", "Weigh yourself first thing in the morning, after using the bathroom, before eating or drinking."),
+    ("Waist", "Waist circumference", "in", "Measure at the narrowest point of your waist, typically just above the belly button."),
+    ("Neck", "Neck circumference", "in", "Measure at the narrowest point, just below the Adam's apple."),
+    ("Chest", "Chest circumference", "in", "Measure at the fullest part of the chest, arms relaxed at sides."),
+    ("Arm", "Upper arm circumference", "in", "Measure at the midpoint between shoulder and elbow, arm relaxed."),
+    ("Thigh", "Thigh circumference", "in", "Measure at the midpoint between hip and knee."),
+    ("Hip", "Hip circumference", "in", "Measure at the widest part of the hips/glutes."),
+    ("Body Fat", "Estimated body fat percentage", "%", "Use calipers or smart scale. Consistent method is more important than absolute accuracy."),
+]
+
 
 async def seed():
     async with async_session() as session:
@@ -88,6 +94,14 @@ async def seed():
                 session.add(Phase(name=name, description=desc, start_date=start, end_date=end, notes=notes))
             print(f"Seeded {len(PHASES)} phases.")
 
+        result = await session.execute(select(MeasurementType).limit(1))
+        if result.scalar_one_or_none():
+            print("Measurement types already seeded, skipping.")
+        else:
+            for name, desc, unit, instructions in MEASUREMENT_TYPES:
+                session.add(MeasurementType(name=name, description=desc, unit=unit, instructions=instructions))
+            print(f"Seeded {len(MEASUREMENT_TYPES)} measurement types.")
+
         await session.commit()