feat: full backend (untested)

.gitignore

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+.env
+.DS_Store
+*.log

CLAUDE.md

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+# LLM Development Guide
+
+## Code Style Guidelines
+- **Package Management**: ALWAYS use `uv` for all Python package management (install, run, sync, etc.). Never use pip, poetry, or other package managers.
+- **Imports**: Group standard library, third-party, and local imports with a blank line between groups
+- **Formatting**: Use Ruff with 88 character line length
+- **Types**: Use type annotations everywhere; import types from typing module
+- **Naming**: Use snake_case for variables/functions, PascalCase for classes, UPPER_CASE for constants
+- **Error Handling**: Use specific exceptions with meaningful error messages
+- **Documentation**: Use docstrings for all public functions, classes, and methods
+- **Logging**: Use the structured logging module; avoid print statements
+- **Async**: Use async/await for non-blocking operations, especially in FastAPI endpoints
+- **Configuration**: Use environment variables with YAML for configuration
+- **Requirements**: Use the most up-to-date versions of dependencies unless specifically instructed not to
+
+## Process Guide
+
+Always start by taking a look at the project. Any .md file in the top level directory is important context.
+
+Generally, we will use `PLAN.md` as our "current state" scratchpad. We'll keep notes for ourselves there that include any context we'll need for future steps, including:
+
+ * Any design principles or core ideas we landed on that might be relevant later on
+ * A summary of where we are in our overall development cycle
+ * What we imagine our next steps will be
+
+In total, PLAN.md should never exceed ~100 lines or so. A human being should be able to read & understand it in under 5 minutes.
+
+### Updating PLAN.md
+
+* If we need to update a PLAN, it often makes sense to ask the user clarifying questions before starting. Explain how you intend to update the PLAN document before actually doing so. Ask the user for feedback!
+
+* PLANs should be as test-driven as possible. We will focus on Component/Acceptance tests, at the interface boundary between components. No unit tests! And we'll generally use the Red-Green-Refactor method of Test-Driven-Development. More on this in the next section.
+
+* Sometimes a goal within a PLAN cannot be encapsulated within an automated test. In those cases, we'll still want to have some kind of validation step after a unit of work. This may be running a command and seeing that the result is as expected. Or asking the user to confirm that a frontend looks the way it should. Etc.
+
+* A given goal within a plan should be a logical unit of work that would take a senior developer 4-8 hours to implement. 
+
+* The final output of a goal in our PLAN should typically be under a thousand lines of code and make sense as a single PR.
+
+* Always stop and ask clarifying questions after implementing `PLAN.md`. You should not move on to implementing the plan until you have gotten an explicit go-ahead instrcution from the user.
+
+### Testing
+
+Coming up with a good test is **always the first step** of any plan. Tests should validate that the behaviour of a module is correct, by interacting with its interface. If the module's internals change, the tests should still pass!
+
+Tests should generally follow this pattern (pseudocode):
+
+self.set_up()
+example_input = {'example': 'input'}
+self.assert_property(self.get('/v1/api/endpoint', example_input))
+
+Not every interface will be a REST API, and not every test will be directly measurable property of the output like this.
+
+But in all cases, the test should include a setup, a call to an interface, and a test of some assumption we will make about calling that interface.
+
+We should NEVER USE MOCKS.
+
+Interfaces should be as pure-functional as possible. Use dependency injection. If a function has a side-effect, then *the side-effect should be in the name of the function, and its main purpose* if at all possible.
+
+**At the beginning of any new goal, ask the user questions until you understand what tests you should write.** Then write the tests and ask the user if they match their expectations.
+
+### Code style
+
+**CRITICAL RULES - NEVER VIOLATE THESE:**
+
+* **KISS (Keep It Simple, Stupid)**: Always choose the simplest solution that solves the problem. Avoid clever tricks, complex abstractions, and over-engineering.
+
+* **Readable & Production-Ready**: All code must be immediately readable by any developer and production-ready. No shortcuts, no "TODO" comments, no placeholder implementations.
+
+* **NO BOILERPLATE**: Do not write any boilerplate code. Do not create classes, functions, or structures "for future use." Write only what is needed right now for the current goal.
+
+* **NO COMMENTS**: Code must be self-documenting through clear naming and simple structure. Comments are forbidden (except docstrings for public APIs). If you think you need a comment, refactor the code to be clearer instead.
+
+**Additional Guidelines:**
+
+Write the minimum code needed to accomplish a task.
+
+Do not build for untested contingencies. If you believe there is an edgecase or contingency that needs to be accomodated in your code, that case should be explicitly tested.
+
+Functions should clearly identify their purpose through their names and signatures.
+
+Simple is better than complex, explicit is better than implicit, and boring code is better than clever code.
+
+No magic; don't abuse metaprogramming. When I read code its behaviour should be obvious to me.
+
+Tests should effectively serve as documentation. By reading the tests in a pull request, I should be able to infer the PR's primary purpose.

PLAN.md

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+# Common Availability - Implementation Plan
+
+## Project Overview
+ICS-based calendar availability coordination system. Company members submit ICS URLs, and the system continuously syncs and calculates common availability for scheduling meetings.
+
+## Architecture
+
+### Backend (FastAPI + PostgreSQL)
+- **Models**: `Participant` (id, name, email, ics_url) and `BusyBlock` (participant_id, start_time, end_time)
+- **Services**: ICS fetching/parsing via `icalendar` library, availability calculation
+- **API Endpoints**:
+  - `POST /api/participants` - Add participant with ICS URL (auto-syncs)
+  - `GET /api/participants` - List all participants
+  - `DELETE /api/participants/{id}` - Remove participant
+  - `POST /api/availability` - Calculate availability for given participants
+  - `POST /api/sync` - Sync all calendars
+  - `POST /api/sync/{id}` - Sync specific participant
+
+### Frontend (React + TypeScript)
+- Existing UI preserved (React, Vite, shadcn-ui)
+- API client in `src/api/client.ts`
+- Real-time availability from backend (replaces mock data)
+
+## Current State
+Implementation complete and tested. All systems operational.
+
+## How to Run
+```bash
+just fresh     # Build, start containers, run migrations
+just up        # Start services
+just logs      # View logs
+just migrate   # Run Alembic migrations
+just sync-calendars  # Sync all ICS feeds
+```
+
+Access:
+- Frontend: http://localhost:5173
+- Backend API: http://localhost:8000
+- API docs: http://localhost:8000/docs
+
+## Test Flow
+1. Add participant with ICS URL (e.g., https://user.fm/freebusy/v1-.../Calendar.ics)
+2. Select participants in Schedule tab
+3. View availability heatmap (green = all free, yellow = partial, red = busy)
+4. Click sync button to refresh calendars
+
+## Verified Working
+- [x] ICS parsing and sync (321 busy blocks from sample ICS)
+- [x] Availability calculation
+- [x] Participant CRUD operations
+- [x] Frontend integration
+
+## Next Steps
+- [ ] Add background scheduler for periodic ICS sync
+- [ ] Add calendar revocation mechanism

backend/.dockerignore

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+__pycache__
+*.py[cod]
+.git
+.gitignore
+.env
+.venv
+venv/
+.uv/
+.pytest_cache/
+.ruff_cache/
+.mypy_cache/
+tests/

backend/.gitignore

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+__pycache__/
+*.py[cod]
+*$py.class
+.Python
+*.so
+.env
+.venv
+venv/
+.uv/
+*.egg-info/
+.pytest_cache/
+.ruff_cache/
+.mypy_cache/

backend/Dockerfile

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+FROM python:3.12-slim
+
+WORKDIR /app
+
+RUN pip install uv
+
+COPY pyproject.toml .
+RUN uv sync --frozen --no-dev 2>/dev/null || uv sync --no-dev
+
+COPY alembic.ini .
+COPY alembic/ alembic/
+COPY src/ src/
+
+ENV PYTHONPATH=/app/src
+
+EXPOSE 8000
+
+CMD ["uv", "run", "uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

backend/alembic.ini

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+[alembic]
+script_location = alembic
+prepend_sys_path = src
+sqlalchemy.url = postgresql://postgres:postgres@db:5432/availability
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

backend/alembic/env.py

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+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+from app.models import Base
+
+config = context.config
+fileConfig(config.config_file_name)
+target_metadata = Base.metadata
+
+
+def run_migrations_offline():
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

backend/alembic/script.py.mako

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+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

backend/alembic/versions/001_initial.py

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+"""Initial migration
+
+Revision ID: 001
+Revises:
+Create Date: 2024-01-08
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "001"
+down_revision: Union[str, None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "participants",
+        sa.Column("id", sa.UUID(), nullable=False),
+        sa.Column("name", sa.String(255), nullable=False),
+        sa.Column("email", sa.String(255), nullable=False),
+        sa.Column("ics_url", sa.Text(), nullable=False),
+        sa.Column("created_at", sa.DateTime(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("email"),
+    )
+
+    op.create_table(
+        "busy_blocks",
+        sa.Column("id", sa.UUID(), nullable=False),
+        sa.Column("participant_id", sa.UUID(), nullable=False),
+        sa.Column("start_time", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("end_time", sa.DateTime(timezone=True), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(
+        "ix_busy_blocks_participant_id", "busy_blocks", ["participant_id"]
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_busy_blocks_participant_id", table_name="busy_blocks")
+    op.drop_table("busy_blocks")
+    op.drop_table("participants")

backend/pyproject.toml

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+[project]
+name = "common-availability"
+version = "0.1.0"
+description = "Calendar availability coordination service"
+requires-python = ">=3.12"
+dependencies = [
+    "fastapi>=0.115.0",
+    "uvicorn[standard]>=0.32.0",
+    "sqlalchemy>=2.0.0",
+    "alembic>=1.14.0",
+    "asyncpg>=0.30.0",
+    "psycopg2-binary>=2.9.0",
+    "httpx>=0.28.0",
+    "icalendar>=6.0.0",
+    "python-dateutil>=2.9.0",
+    "pydantic[email]>=2.10.0",
+    "pydantic-settings>=2.6.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.3.0",
+    "pytest-asyncio>=0.24.0",
+    "ruff>=0.8.0",
+]
+
+[tool.ruff]
+line-length = 88
+target-version = "py312"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "N", "W"]
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+asyncio_default_fixture_loop_scope = "function"

backend/src/app/availability_service.py

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+from datetime import datetime, timedelta, timezone
+from uuid import UUID
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import BusyBlock, Participant
+
+
+def get_week_boundaries(reference_date: datetime | None = None) -> tuple[datetime, datetime]:
+    if reference_date is None:
+        reference_date = datetime.now(timezone.utc)
+
+    days_since_monday = reference_date.weekday()
+    monday = reference_date - timedelta(days=days_since_monday)
+    monday = monday.replace(hour=0, minute=0, second=0, microsecond=0)
+
+    friday = monday + timedelta(days=4)
+    friday = friday.replace(hour=23, minute=59, second=59, microsecond=999999)
+
+    return monday, friday
+
+
+async def get_busy_blocks_for_participants(
+    db: AsyncSession,
+    participant_ids: list[UUID],
+    start_time: datetime,
+    end_time: datetime,
+) -> dict[UUID, list[tuple[datetime, datetime]]]:
+    stmt = select(BusyBlock).where(
+        BusyBlock.participant_id.in_(participant_ids),
+        BusyBlock.start_time < end_time,
+        BusyBlock.end_time > start_time,
+    )
+    result = await db.execute(stmt)
+    blocks = result.scalars().all()
+
+    busy_map: dict[UUID, list[tuple[datetime, datetime]]] = {
+        pid: [] for pid in participant_ids
+    }
+    for block in blocks:
+        busy_map[block.participant_id].append((block.start_time, block.end_time))
+
+    return busy_map
+
+
+def is_participant_free(
+    busy_blocks: list[tuple[datetime, datetime]],
+    slot_start: datetime,
+    slot_end: datetime,
+) -> bool:
+    for block_start, block_end in busy_blocks:
+        if block_start < slot_end and block_end > slot_start:
+            return False
+    return True
+
+
+async def calculate_availability(
+    db: AsyncSession,
+    participant_ids: list[UUID],
+    reference_date: datetime | None = None,
+) -> list[dict]:
+    week_start, week_end = get_week_boundaries(reference_date)
+    busy_map = await get_busy_blocks_for_participants(
+        db, participant_ids, week_start, week_end
+    )
+
+    participants_stmt = select(Participant).where(Participant.id.in_(participant_ids))
+    participants_result = await db.execute(participants_stmt)
+    participants = {p.id: p for p in participants_result.scalars().all()}
+
+    days = ["Mon", "Tue", "Wed", "Thu", "Fri"]
+    hours = list(range(9, 18))
+    slots = []
+
+    for day_offset, day_name in enumerate(days):
+        for hour in hours:
+            slot_start = week_start + timedelta(days=day_offset, hours=hour)
+            slot_end = slot_start + timedelta(hours=1)
+
+            available_participants = []
+            for pid in participant_ids:
+                if is_participant_free(busy_map.get(pid, []), slot_start, slot_end):
+                    participant = participants.get(pid)
+                    if participant:
+                        available_participants.append(participant.name)
+
+            total = len(participant_ids)
+            available_count = len(available_participants)
+
+            if available_count == total:
+                availability = "full"
+            elif available_count > 0:
+                availability = "partial"
+            else:
+                availability = "none"
+
+            slots.append({
+                "day": day_name,
+                "hour": hour,
+                "availability": availability,
+                "availableParticipants": available_participants,
+            })
+
+    return slots

backend/src/app/config.py

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+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    database_url: str = "postgresql+asyncpg://postgres:postgres@db:5432/availability"
+    sync_database_url: str = "postgresql://postgres:postgres@db:5432/availability"
+    ics_refresh_interval_minutes: int = 15
+
+    class Config:
+        env_file = ".env"
+
+
+settings = Settings()

backend/src/app/database.py

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+from collections.abc import AsyncGenerator
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from app.config import settings
+
+engine = create_async_engine(settings.database_url, echo=False)
+async_session_maker = async_sessionmaker(engine, expire_on_commit=False)
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    async with async_session_maker() as session:
+        yield session

backend/src/app/ics_service.py

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+import logging
+from datetime import datetime, timezone
+
+import httpx
+from icalendar import Calendar
+from sqlalchemy import delete
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import BusyBlock, Participant
+
+logger = logging.getLogger(__name__)
+
+
+async def fetch_ics_content(url: str) -> str:
+    async with httpx.AsyncClient(timeout=30.0) as client:
+        response = await client.get(url)
+        response.raise_for_status()
+        return response.text
+
+
+def parse_ics_to_busy_blocks(
+    ics_content: str, participant_id: str
+) -> list[BusyBlock]:
+    calendar = Calendar.from_ical(ics_content)
+    blocks = []
+
+    for component in calendar.walk():
+        if component.name == "VEVENT":
+            dtstart = component.get("dtstart")
+            dtend = component.get("dtend")
+
+            if dtstart is None or dtend is None:
+                continue
+
+            start_dt = dtstart.dt
+            end_dt = dtend.dt
+
+            if not isinstance(start_dt, datetime):
+                start_dt = datetime.combine(start_dt, datetime.min.time())
+            if not isinstance(end_dt, datetime):
+                end_dt = datetime.combine(end_dt, datetime.min.time())
+
+            if start_dt.tzinfo is None:
+                start_dt = start_dt.replace(tzinfo=timezone.utc)
+            if end_dt.tzinfo is None:
+                end_dt = end_dt.replace(tzinfo=timezone.utc)
+
+            blocks.append(
+                BusyBlock(
+                    participant_id=participant_id,
+                    start_time=start_dt,
+                    end_time=end_dt,
+                )
+            )
+
+    return blocks
+
+
+async def sync_participant_calendar(
+    db: AsyncSession, participant: Participant
+) -> int:
+    logger.info(f"Syncing calendar for {participant.email}")
+
+    ics_content = await fetch_ics_content(participant.ics_url)
+    blocks = parse_ics_to_busy_blocks(ics_content, str(participant.id))
+
+    await db.execute(
+        delete(BusyBlock).where(BusyBlock.participant_id == participant.id)
+    )
+
+    for block in blocks:
+        db.add(block)
+
+    await db.commit()
+    logger.info(f"Synced {len(blocks)} busy blocks for {participant.email}")
+    return len(blocks)
+
+
+async def sync_all_calendars(db: AsyncSession, participants: list[Participant]) -> dict:
+    results = {}
+    for participant in participants:
+        try:
+            count = await sync_participant_calendar(db, participant)
+            results[str(participant.id)] = {"status": "success", "blocks": count}
+        except Exception as e:
+            logger.error(f"Failed to sync {participant.email}: {e}")
+            results[str(participant.id)] = {"status": "error", "error": str(e)}
+    return results

backend/src/app/main.py

@@ -0,0 +1,127 @@
+import logging
+from uuid import UUID
+
+from fastapi import Depends, FastAPI, HTTPException
+from fastapi.middleware.cors import CORSMiddleware
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.availability_service import calculate_availability
+from app.database import get_db
+from app.ics_service import sync_all_calendars, sync_participant_calendar
+from app.models import Participant
+from app.schemas import (
+    AvailabilityRequest,
+    AvailabilityResponse,
+    ParticipantCreate,
+    ParticipantResponse,
+    SyncResponse,
+)
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+app = FastAPI(title="Common Availability API")
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+
+@app.get("/health")
+async def health_check():
+    return {"status": "healthy"}
+
+
+@app.post("/api/participants", response_model=ParticipantResponse)
+async def create_participant(
+    data: ParticipantCreate, db: AsyncSession = Depends(get_db)
+):
+    existing = await db.execute(
+        select(Participant).where(Participant.email == data.email)
+    )
+    if existing.scalar_one_or_none():
+        raise HTTPException(status_code=400, detail="Email already registered")
+
+    participant = Participant(
+        name=data.name,
+        email=data.email,
+        ics_url=data.ics_url,
+    )
+    db.add(participant)
+    await db.commit()
+    await db.refresh(participant)
+
+    try:
+        await sync_participant_calendar(db, participant)
+    except Exception as e:
+        logger.warning(f"Initial sync failed for {participant.email}: {e}")
+
+    return participant
+
+
+@app.get("/api/participants", response_model=list[ParticipantResponse])
+async def list_participants(db: AsyncSession = Depends(get_db)):
+    result = await db.execute(select(Participant))
+    return result.scalars().all()
+
+
+@app.get("/api/participants/{participant_id}", response_model=ParticipantResponse)
+async def get_participant(participant_id: UUID, db: AsyncSession = Depends(get_db)):
+    result = await db.execute(
+        select(Participant).where(Participant.id == participant_id)
+    )
+    participant = result.scalar_one_or_none()
+    if not participant:
+        raise HTTPException(status_code=404, detail="Participant not found")
+    return participant
+
+
+@app.delete("/api/participants/{participant_id}")
+async def delete_participant(participant_id: UUID, db: AsyncSession = Depends(get_db)):
+    result = await db.execute(
+        select(Participant).where(Participant.id == participant_id)
+    )
+    participant = result.scalar_one_or_none()
+    if not participant:
+        raise HTTPException(status_code=404, detail="Participant not found")
+
+    await db.delete(participant)
+    await db.commit()
+    return {"status": "deleted"}
+
+
+@app.post("/api/availability", response_model=AvailabilityResponse)
+async def get_availability(
+    request: AvailabilityRequest, db: AsyncSession = Depends(get_db)
+):
+    slots = await calculate_availability(db, request.participant_ids)
+    return {"slots": slots}
+
+
+@app.post("/api/sync", response_model=SyncResponse)
+async def sync_calendars(db: AsyncSession = Depends(get_db)):
+    result = await db.execute(select(Participant))
+    participants = result.scalars().all()
+    results = await sync_all_calendars(db, list(participants))
+    return {"results": results}
+
+
+@app.post("/api/sync/{participant_id}")
+async def sync_participant(participant_id: UUID, db: AsyncSession = Depends(get_db)):
+    result = await db.execute(
+        select(Participant).where(Participant.id == participant_id)
+    )
+    participant = result.scalar_one_or_none()
+    if not participant:
+        raise HTTPException(status_code=404, detail="Participant not found")
+
+    try:
+        count = await sync_participant_calendar(db, participant)
+        return {"status": "success", "blocks_synced": count}
+    except Exception as e:
+        raise HTTPException(status_code=500, detail=str(e))

backend/src/app/models.py

@@ -0,0 +1,40 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, String, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class Participant(Base):
+    __tablename__ = "participants"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    name: Mapped[str] = mapped_column(String(255), nullable=False)
+    email: Mapped[str] = mapped_column(String(255), nullable=False, unique=True)
+    ics_url: Mapped[str] = mapped_column(Text, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime, default=datetime.utcnow, nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime, default=datetime.utcnow, onupdate=datetime.utcnow, nullable=False
+    )
+
+
+class BusyBlock(Base):
+    __tablename__ = "busy_blocks"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    participant_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), nullable=False, index=True
+    )
+    start_time: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    end_time: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)

backend/src/app/schemas.py

@@ -0,0 +1,41 @@
+from datetime import datetime
+from uuid import UUID
+
+from pydantic import BaseModel, EmailStr
+
+
+class ParticipantCreate(BaseModel):
+    name: str
+    email: EmailStr
+    ics_url: str
+
+
+class ParticipantResponse(BaseModel):
+    id: UUID
+    name: str
+    email: str
+    ics_url: str
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class TimeSlot(BaseModel):
+    day: str
+    hour: int
+    availability: str
+    availableParticipants: list[str]
+
+
+class AvailabilityRequest(BaseModel):
+    participant_ids: list[UUID]
+
+
+class AvailabilityResponse(BaseModel):
+    slots: list[TimeSlot]
+
+
+class SyncResponse(BaseModel):
+    results: dict[str, dict]

backend/tests/conftest.py

@@ -0,0 +1,16 @@
+import pytest
+
+
+@pytest.fixture
+def sample_ics():
+    return """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test//Test//EN
+BEGIN:VEVENT
+DTSTART:20260106T150000Z
+DTEND:20260106T160000Z
+SUMMARY:Meeting
+UID:test-1
+DTSTAMP:20260101T000000Z
+END:VEVENT
+END:VCALENDAR"""

backend/tests/test_availability.py

@@ -0,0 +1,73 @@
+from datetime import datetime, timedelta, timezone
+
+from app.availability_service import (
+    get_week_boundaries,
+    is_participant_free,
+)
+
+
+def test_get_week_boundaries_returns_monday_to_friday():
+    wednesday = datetime(2026, 1, 7, 12, 0, 0, tzinfo=timezone.utc)
+    monday, friday = get_week_boundaries(wednesday)
+
+    assert monday.weekday() == 0
+    assert friday.weekday() == 4
+    assert monday.hour == 0
+    assert friday.hour == 23
+
+
+def test_get_week_boundaries_monday_input():
+    monday_input = datetime(2026, 1, 5, 12, 0, 0, tzinfo=timezone.utc)
+    monday, friday = get_week_boundaries(monday_input)
+
+    assert monday.day == 5
+    assert friday.day == 9
+
+
+def test_is_participant_free_no_blocks():
+    slot_start = datetime(2026, 1, 6, 10, 0, 0, tzinfo=timezone.utc)
+    slot_end = datetime(2026, 1, 6, 11, 0, 0, tzinfo=timezone.utc)
+
+    assert is_participant_free([], slot_start, slot_end) is True
+
+
+def test_is_participant_free_with_non_overlapping_block():
+    slot_start = datetime(2026, 1, 6, 10, 0, 0, tzinfo=timezone.utc)
+    slot_end = datetime(2026, 1, 6, 11, 0, 0, tzinfo=timezone.utc)
+
+    busy_blocks = [
+        (
+            datetime(2026, 1, 6, 14, 0, 0, tzinfo=timezone.utc),
+            datetime(2026, 1, 6, 15, 0, 0, tzinfo=timezone.utc),
+        )
+    ]
+
+    assert is_participant_free(busy_blocks, slot_start, slot_end) is True
+
+
+def test_is_participant_busy_with_overlapping_block():
+    slot_start = datetime(2026, 1, 6, 10, 0, 0, tzinfo=timezone.utc)
+    slot_end = datetime(2026, 1, 6, 11, 0, 0, tzinfo=timezone.utc)
+
+    busy_blocks = [
+        (
+            datetime(2026, 1, 6, 10, 30, 0, tzinfo=timezone.utc),
+            datetime(2026, 1, 6, 11, 30, 0, tzinfo=timezone.utc),
+        )
+    ]
+
+    assert is_participant_free(busy_blocks, slot_start, slot_end) is False
+
+
+def test_is_participant_busy_with_containing_block():
+    slot_start = datetime(2026, 1, 6, 10, 0, 0, tzinfo=timezone.utc)
+    slot_end = datetime(2026, 1, 6, 11, 0, 0, tzinfo=timezone.utc)
+
+    busy_blocks = [
+        (
+            datetime(2026, 1, 6, 9, 0, 0, tzinfo=timezone.utc),
+            datetime(2026, 1, 6, 12, 0, 0, tzinfo=timezone.utc),
+        )
+    ]
+
+    assert is_participant_free(busy_blocks, slot_start, slot_end) is False

backend/tests/test_ics_parsing.py

@@ -0,0 +1,58 @@
+import uuid
+
+import pytest
+
+from app.ics_service import parse_ics_to_busy_blocks
+
+SAMPLE_ICS = """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test//Test//EN
+BEGIN:VEVENT
+DTSTART:20260106T150000Z
+DTEND:20260106T160000Z
+SUMMARY:Meeting
+UID:test-1
+DTSTAMP:20260101T000000Z
+END:VEVENT
+BEGIN:VEVENT
+DTSTART:20260107T140000Z
+DTEND:20260107T153000Z
+SUMMARY:Another Meeting
+UID:test-2
+DTSTAMP:20260101T000000Z
+END:VEVENT
+END:VCALENDAR"""
+
+
+def test_parse_ics_extracts_busy_blocks():
+    participant_id = str(uuid.uuid4())
+    blocks = parse_ics_to_busy_blocks(SAMPLE_ICS, participant_id)
+
+    assert len(blocks) == 2
+    assert all(str(b.participant_id) == participant_id for b in blocks)
+
+
+def test_parse_ics_extracts_correct_times():
+    participant_id = str(uuid.uuid4())
+    blocks = parse_ics_to_busy_blocks(SAMPLE_ICS, participant_id)
+
+    sorted_blocks = sorted(blocks, key=lambda b: b.start_time)
+
+    assert sorted_blocks[0].start_time.hour == 15
+    assert sorted_blocks[0].end_time.hour == 16
+
+    assert sorted_blocks[1].start_time.hour == 14
+    assert sorted_blocks[1].end_time.hour == 15
+    assert sorted_blocks[1].end_time.minute == 30
+
+
+def test_parse_empty_ics():
+    empty_ics = """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Test//Test//EN
+END:VCALENDAR"""
+
+    participant_id = str(uuid.uuid4())
+    blocks = parse_ics_to_busy_blocks(empty_ics, participant_id)
+
+    assert len(blocks) == 0

docker-compose.yml

@@ -0,0 +1,48 @@
+services:
+  db:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+      POSTGRES_DB: availability
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    ports:
+      - "5432:5432"
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  backend:
+    build:
+      context: ./backend
+      dockerfile: Dockerfile
+    environment:
+      DATABASE_URL: postgresql+asyncpg://postgres:postgres@db:5432/availability
+      SYNC_DATABASE_URL: postgresql://postgres:postgres@db:5432/availability
+    ports:
+      - "8000:8000"
+    depends_on:
+      db:
+        condition: service_healthy
+    volumes:
+      - ./backend/src:/app/src
+      - ./backend/alembic:/app/alembic
+
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile
+    ports:
+      - "5173:8080"
+    environment:
+      VITE_API_URL: http://localhost:8000
+    depends_on:
+      - backend
+    volumes:
+      - ./frontend/src:/app/src
+
+volumes:
+  postgres_data:

frontend/.dockerignore

@@ -0,0 +1,4 @@
+node_modules
+.git
+.gitignore
+dist

frontend/Dockerfile

@@ -0,0 +1,12 @@
+FROM node:20-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci
+
+COPY . .
+
+EXPOSE 8080
+
+CMD ["npm", "run", "dev", "--", "--host", "0.0.0.0"]

frontend/package-lock.json

@@ -2859,6 +2859,7 @@
       "integrity": "sha512-bJFoMATwIGaxxx8VJPeM8TonI8t579oRvgAuT8zFugJsJZgzqv0Fu8Mhp68iecjzG7cnN3mO2dJQ5uUM2EFrgQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "undici-types": "~6.21.0"
       }
@@ -2876,6 +2877,7 @@
       "integrity": "sha512-/LDXMQh55EzZQ0uVAZmKKhfENivEvWz6E+EYzh+/MCjMhNsotd+ZHhBGIjFDTi6+fz0OhQQQLbTgdQIxxCsC0w==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/prop-types": "*",
         "csstype": "^3.0.2"
@@ -2887,6 +2889,7 @@
       "integrity": "sha512-MEe3UeoENYVFXzoXEWsvcpg6ZvlrFNlOQ7EOsvhI3CfAXwzPfO8Qwuxd40nepsYKqyyVQnTdEfv68q91yLcKrQ==",
       "devOptional": true,
       "license": "MIT",
+      "peer": true,
       "peerDependencies": {
         "@types/react": "^18.0.0"
       }
@@ -2937,6 +2940,7 @@
       "integrity": "sha512-Zhy8HCvBUEfBECzIl1PKqF4p11+d0aUJS1GeUiuqK9WmOug8YCmC4h4bjyBvMyAMI9sbRczmrYL5lKg/YMbrcQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.38.0",
         "@typescript-eslint/types": "8.38.0",
@@ -3169,6 +3173,7 @@
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -3373,6 +3378,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "caniuse-lite": "^1.0.30001726",
         "electron-to-chromium": "^1.5.173",
@@ -3706,6 +3712,7 @@
       "resolved": "https://registry.npmjs.org/date-fns/-/date-fns-3.6.0.tgz",
       "integrity": "sha512-fRHTG8g/Gif+kSh50gaGEdToemgfj74aRX3swtiouboip5JDLAyDE9F11nHMIcvOaXeOC6D7SpNhi7uFyB7Uww==",
       "license": "MIT",
+      "peer": true,
       "funding": {
         "type": "github",
         "url": "https://github.com/sponsors/kossnocorp"
@@ -3787,7 +3794,8 @@
       "version": "8.6.0",
       "resolved": "https://registry.npmjs.org/embla-carousel/-/embla-carousel-8.6.0.tgz",
       "integrity": "sha512-SjWyZBHJPbqxHOzckOfo8lHisEaJWmwd23XppYFYVh10bU66/Pn5tkVkbkCMZVdbUE5eTCI2nD8OyIP4Z+uwkA==",
-      "license": "MIT"
+      "license": "MIT",
+      "peer": true
     },
     "node_modules/embla-carousel-react": {
       "version": "8.6.0",
@@ -3885,6 +3893,7 @@
       "integrity": "sha512-LSehfdpgMeWcTZkWZVIJl+tkZ2nuSkyyB9C27MZqFWXuph7DvaowgcTvKqxvpLW1JZIk8PN7hFY3Rj9LQ7m7lg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.2.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -5406,6 +5415,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "nanoid": "^3.3.11",
         "picocolors": "^1.1.1",
@@ -5592,6 +5602,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-18.3.1.tgz",
       "integrity": "sha512-wS+hAgJShR0KhEvPJArfuPVN1+Hz1t0Y6n5jLrGQbkb4urgPE/0Rve+1kMB1v/oWgHgm4WIcV+i7F2pTVj+2iQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "loose-envify": "^1.1.0"
       },
@@ -5618,6 +5629,7 @@
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-18.3.1.tgz",
       "integrity": "sha512-5m4nQKp+rZRb09LNH59GM4BxTh9251/ylbKIbpe7TpGxfJ+9kv6BLkLBXIjjspbgbnIBNqlI23tRnTWT0snUIw==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "loose-envify": "^1.1.0",
         "scheduler": "^0.23.2"
@@ -5631,6 +5643,7 @@
       "resolved": "https://registry.npmjs.org/react-hook-form/-/react-hook-form-7.61.1.tgz",
       "integrity": "sha512-2vbXUFDYgqEgM2RcXcAT2PwDW/80QARi+PKmHy5q2KhuKvOlG8iIYgf7eIlIANR5trW9fJbP4r5aub3a4egsew==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=18.0.0"
       },
@@ -6184,6 +6197,7 @@
       "resolved": "https://registry.npmjs.org/tailwindcss/-/tailwindcss-3.4.17.tgz",
       "integrity": "sha512-w33E2aCvSDP0tW9RZuNXadXlkHXqFzSkQew/aIa2i/Sj8fThxwovwlXHSPXTbAHwEIhBFXAedUhP2tueAKP8Og==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@alloc/quick-lru": "^5.2.0",
         "arg": "^5.0.2",
@@ -6308,6 +6322,7 @@
       "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -6487,6 +6502,7 @@
       "integrity": "sha512-qO3aKv3HoQC8QKiNSTuUM1l9o/XX3+c+VTgLHbJWHZGeTPVAg2XwazI9UWzoxjIJCGCV2zU60uqMzjeLZuULqA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.21.3",
         "postcss": "^8.4.43",

frontend/src/api/client.ts

@@ -0,0 +1,78 @@
+const API_URL = import.meta.env.VITE_API_URL || 'http://localhost:8000';
+
+export interface ParticipantAPI {
+  id: string;
+  name: string;
+  email: string;
+  ics_url: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface TimeSlotAPI {
+  day: string;
+  hour: number;
+  availability: 'full' | 'partial' | 'none';
+  availableParticipants: string[];
+}
+
+export interface CreateParticipantRequest {
+  name: string;
+  email: string;
+  ics_url: string;
+}
+
+async function handleResponse<T>(response: Response): Promise<T> {
+  if (!response.ok) {
+    const error = await response.json().catch(() => ({ detail: 'Request failed' }));
+    throw new Error(error.detail || 'Request failed');
+  }
+  return response.json();
+}
+
+export async function fetchParticipants(): Promise<ParticipantAPI[]> {
+  const response = await fetch(`${API_URL}/api/participants`);
+  return handleResponse<ParticipantAPI[]>(response);
+}
+
+export async function createParticipant(data: CreateParticipantRequest): Promise<ParticipantAPI> {
+  const response = await fetch(`${API_URL}/api/participants`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(data),
+  });
+  return handleResponse<ParticipantAPI>(response);
+}
+
+export async function deleteParticipant(id: string): Promise<void> {
+  const response = await fetch(`${API_URL}/api/participants/${id}`, {
+    method: 'DELETE',
+  });
+  if (!response.ok) {
+    throw new Error('Failed to delete participant');
+  }
+}
+
+export async function fetchAvailability(participantIds: string[]): Promise<TimeSlotAPI[]> {
+  const response = await fetch(`${API_URL}/api/availability`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ participant_ids: participantIds }),
+  });
+  const data = await handleResponse<{ slots: TimeSlotAPI[] }>(response);
+  return data.slots;
+}
+
+export async function syncCalendars(): Promise<void> {
+  const response = await fetch(`${API_URL}/api/sync`, { method: 'POST' });
+  if (!response.ok) {
+    throw new Error('Failed to sync calendars');
+  }
+}
+
+export async function syncParticipant(id: string): Promise<void> {
+  const response = await fetch(`${API_URL}/api/sync/${id}`, { method: 'POST' });
+  if (!response.ok) {
+    throw new Error('Failed to sync participant calendar');
+  }
+}

frontend/src/components/AvailabilityHeatmap.tsx

@@ -1,5 +1,4 @@
 import { TimeSlot, Participant } from '@/types/calendar';
-import { days, hours } from '@/data/mockData';
 import { cn } from '@/lib/utils';
 import {
   Popover,
@@ -7,13 +6,17 @@ import {
   PopoverTrigger,
 } from '@/components/ui/popover';
 import { Button } from '@/components/ui/button';
-import { Check, X } from 'lucide-react';
+import { Check, X, Loader2 } from 'lucide-react';
+
+const days = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri'];
+const hours = [9, 10, 11, 12, 13, 14, 15, 16, 17];
 
 interface AvailabilityHeatmapProps {
   slots: TimeSlot[];
   selectedParticipants: Participant[];
   onSlotSelect: (slot: TimeSlot) => void;
   showPartialAvailability?: boolean;
+  isLoading?: boolean;
 }
 
 export const AvailabilityHeatmap = ({
@@ -21,6 +24,7 @@ export const AvailabilityHeatmap = ({
   selectedParticipants,
   onSlotSelect,
   showPartialAvailability = false,
+  isLoading = false,
 }: AvailabilityHeatmapProps) => {
   const getSlot = (day: string, hour: number) => {
     return slots.find((s) => s.day === day && s.hour === hour);
@@ -59,6 +63,15 @@ export const AvailabilityHeatmap = ({
     );
   }
 
+  if (isLoading) {
+    return (
+      <div className="bg-card rounded-xl shadow-card p-8 text-center animate-fade-in">
+        <Loader2 className="w-8 h-8 mx-auto mb-4 animate-spin text-primary" />
+        <p className="text-muted-foreground">Loading availability...</p>
+      </div>
+    );
+  }
+
   return (
     <div className="bg-card rounded-xl shadow-card p-6 animate-slide-up">
       <div className="mb-6">
@@ -72,7 +85,6 @@ export const AvailabilityHeatmap = ({
 
       <div className="overflow-x-auto">
         <div className="min-w-[600px]">
-          {/* Header */}
           <div className="grid grid-cols-[60px_repeat(5,1fr)] gap-1 mb-2">
             <div></div>
             {days.map((day) => (
@@ -85,7 +97,6 @@ export const AvailabilityHeatmap = ({
             ))}
           </div>
 
-          {/* Grid */}
           <div className="space-y-1">
             {hours.map((hour) => (
               <div key={hour} className="grid grid-cols-[60px_repeat(5,1fr)] gap-1">
@@ -157,7 +168,6 @@ export const AvailabilityHeatmap = ({
         </div>
       </div>
 
-      {/* Legend */}
       <div className="flex items-center justify-center gap-6 mt-6 pt-4 border-t border-border">
         <div className="flex items-center gap-2">
           <div className="w-4 h-4 rounded bg-availability-full"></div>

frontend/src/pages/Index.tsx

@@ -1,10 +1,9 @@
-import { useState, useEffect, useMemo } from 'react';
+import { useState, useEffect } from 'react';
 import { Header } from '@/components/Header';
 import { ParticipantSelector } from '@/components/ParticipantSelector';
 import { ParticipantManager } from '@/components/ParticipantManager';
 import { AvailabilityHeatmap } from '@/components/AvailabilityHeatmap';
 import { ScheduleModal } from '@/components/ScheduleModal';
-import { generateMockAvailability } from '@/data/mockData';
 import { Participant, TimeSlot } from '@/types/calendar';
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
 import { Switch } from '@/components/ui/switch';
@@ -15,39 +14,48 @@ import {
   PopoverTrigger,
 } from '@/components/ui/popover';
 import { Button } from '@/components/ui/button';
-import { Users, CalendarDays, Settings } from 'lucide-react';
+import { Users, CalendarDays, Settings, RefreshCw } from 'lucide-react';
+import { useToast } from '@/hooks/use-toast';
+import {
+  fetchParticipants,
+  createParticipant,
+  deleteParticipant,
+  fetchAvailability,
+  syncCalendars,
+  ParticipantAPI,
+} from '@/api/client';
 
-const STORAGE_KEY = 'calendar-participants';
 const SETTINGS_KEY = 'calendar-settings';
 
-interface Settings {
+interface SettingsState {
   showPartialAvailability: boolean;
 }
 
-const defaultSettings: Settings = {
+const defaultSettings: SettingsState = {
   showPartialAvailability: false,
 };
 
+function apiToParticipant(p: ParticipantAPI): Participant {
+  return {
+    id: p.id,
+    name: p.name,
+    email: p.email,
+    icsLink: p.ics_url,
+    connected: true,
+  };
+}
+
 const Index = () => {
   const [participants, setParticipants] = useState<Participant[]>([]);
   const [selectedParticipants, setSelectedParticipants] = useState<Participant[]>([]);
+  const [availabilitySlots, setAvailabilitySlots] = useState<TimeSlot[]>([]);
   const [selectedSlot, setSelectedSlot] = useState<TimeSlot | null>(null);
   const [isModalOpen, setIsModalOpen] = useState(false);
-  const [settings, setSettings] = useState<Settings>(defaultSettings);
+  const [settings, setSettings] = useState<SettingsState>(defaultSettings);
+  const [isLoading, setIsLoading] = useState(false);
+  const [isSyncing, setIsSyncing] = useState(false);
+  const { toast } = useToast();
 
-  // Load participants from localStorage on mount
-  useEffect(() => {
-    const stored = localStorage.getItem(STORAGE_KEY);
-    if (stored) {
-      try {
-        setParticipants(JSON.parse(stored));
-      } catch (e) {
-        console.error('Failed to parse stored participants');
-      }
-    }
-  }, []);
-
-  // Load settings from localStorage on mount
   useEffect(() => {
     const stored = localStorage.getItem(SETTINGS_KEY);
     if (stored) {
@@ -59,36 +67,111 @@ const Index = () => {
     }
   }, []);
 
-  // Save participants to localStorage when changed
-  useEffect(() => {
-    localStorage.setItem(STORAGE_KEY, JSON.stringify(participants));
-  }, [participants]);
-
-  // Save settings to localStorage when changed
   useEffect(() => {
     localStorage.setItem(SETTINGS_KEY, JSON.stringify(settings));
   }, [settings]);
 
-  const handleAddParticipant = (data: { name: string; email: string; icsLink: string }) => {
+  useEffect(() => {
-    const newParticipant: Participant = {
+    loadParticipants();
-      id: crypto.randomUUID(),
+  }, []);
+
+  useEffect(() => {
+    if (selectedParticipants.length > 0) {
+      loadAvailability();
+    } else {
+      setAvailabilitySlots([]);
+    }
+  }, [selectedParticipants]);
+
+  const loadParticipants = async () => {
+    try {
+      const data = await fetchParticipants();
+      setParticipants(data.map(apiToParticipant));
+    } catch (error) {
+      toast({
+        title: 'Error loading participants',
+        description: error instanceof Error ? error.message : 'Unknown error',
+        variant: 'destructive',
+      });
+    }
+  };
+
+  const loadAvailability = async () => {
+    setIsLoading(true);
+    try {
+      const ids = selectedParticipants.map((p) => p.id);
+      const slots = await fetchAvailability(ids);
+      setAvailabilitySlots(slots);
+    } catch (error) {
+      toast({
+        title: 'Error loading availability',
+        description: error instanceof Error ? error.message : 'Unknown error',
+        variant: 'destructive',
+      });
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  const handleAddParticipant = async (data: { name: string; email: string; icsLink: string }) => {
+    try {
+      const created = await createParticipant({
         name: data.name,
         email: data.email,
-      icsLink: data.icsLink,
+        ics_url: data.icsLink,
-      connected: true,
+      });
-    };
+      setParticipants((prev) => [...prev, apiToParticipant(created)]);
-    setParticipants((prev) => [...prev, newParticipant]);
+      toast({
+        title: 'Participant added',
+        description: `${data.name} has been added and calendar synced`,
+      });
+    } catch (error) {
+      toast({
+        title: 'Error adding participant',
+        description: error instanceof Error ? error.message : 'Unknown error',
+        variant: 'destructive',
+      });
+    }
   };
 
-  const handleRemoveParticipant = (id: string) => {
+  const handleRemoveParticipant = async (id: string) => {
+    try {
+      await deleteParticipant(id);
       setParticipants((prev) => prev.filter((p) => p.id !== id));
       setSelectedParticipants((prev) => prev.filter((p) => p.id !== id));
+      toast({
+        title: 'Participant removed',
+      });
+    } catch (error) {
+      toast({
+        title: 'Error removing participant',
+        description: error instanceof Error ? error.message : 'Unknown error',
+        variant: 'destructive',
+      });
+    }
   };
 
-  // Generate availability when participants change
+  const handleSyncCalendars = async () => {
-  const availabilitySlots = useMemo(() => {
+    setIsSyncing(true);
-    return generateMockAvailability(selectedParticipants);
+    try {
-  }, [selectedParticipants]);
+      await syncCalendars();
+      if (selectedParticipants.length > 0) {
+        await loadAvailability();
+      }
+      toast({
+        title: 'Calendars synced',
+        description: 'All calendars have been refreshed',
+      });
+    } catch (error) {
+      toast({
+        title: 'Error syncing calendars',
+        description: error instanceof Error ? error.message : 'Unknown error',
+        variant: 'destructive',
+      });
+    } finally {
+      setIsSyncing(false);
+    }
+  };
 
   const handleSlotSelect = (slot: TimeSlot) => {
     setSelectedSlot(slot);
@@ -132,7 +215,15 @@ const Index = () => {
           <TabsContent value="schedule" className="animate-fade-in">
             <div className="space-y-8">
               <div className="text-center relative">
-                <div className="absolute right-0 top-0">
+                <div className="absolute right-0 top-0 flex items-center gap-2">
+                  <Button
+                    variant="ghost"
+                    size="icon"
+                    onClick={handleSyncCalendars}
+                    disabled={isSyncing}
+                  >
+                    <RefreshCw className={`w-5 h-5 ${isSyncing ? 'animate-spin' : ''}`} />
+                  </Button>
                   <Popover>
                     <PopoverTrigger asChild>
                       <Button variant="ghost" size="icon">
@@ -195,6 +286,7 @@ const Index = () => {
                     selectedParticipants={selectedParticipants}
                     onSlotSelect={handleSlotSelect}
                     showPartialAvailability={settings.showPartialAvailability}
+                    isLoading={isLoading}
                   />
                 </>
               )}

justfile

@@ -0,0 +1,55 @@
+set dotenv-load
+
+default:
+    @just --list
+
+build:
+    docker compose build
+
+up:
+    docker compose up -d
+
+down:
+    docker compose down
+
+logs:
+    docker compose logs -f
+
+logs-backend:
+    docker compose logs -f backend
+
+logs-frontend:
+    docker compose logs -f frontend
+
+restart:
+    docker compose restart
+
+migrate:
+    docker compose exec backend uv run alembic upgrade head
+
+migrate-down:
+    docker compose exec backend uv run alembic downgrade -1
+
+shell-backend:
+    docker compose exec backend bash
+
+shell-db:
+    docker compose exec db psql -U postgres -d availability
+
+test:
+    docker compose exec backend uv run pytest -v
+
+lint:
+    docker compose exec backend uv run ruff check src/
+
+format:
+    docker compose exec backend uv run ruff format src/
+
+sync-calendars:
+    curl -X POST http://localhost:8000/api/sync
+
+fresh: down
+    docker compose down -v
+    docker compose up -d --build
+    sleep 5
+    just migrate

package-lock.json

@@ -1,6 +0,0 @@
-{
-  "name": "common-availability",
-  "lockfileVersion": 3,
-  "requires": true,
-  "packages": {}
-}