fixing import for tests

* chore: cleaning gitignore

* formating and env documentation

* feat: context switching of hotel/airline depndent on env var via middleware

* fixed alignment and building

* wrong file

* prods

* fixed applying style

* better session cookie management

* tentative session storage with maybe using airtable

* migrated api of ingestion

* events and products apge

* fixing build

* 13 create outline for research paper draft (#18)

* updated outline for paper from issue

* extra paper sections and some formalization of series data

* algorithms and acknowledgements

* updated outline for paper from issue

* upadted text formating

* event unification

* refactor tracking to ues callbacks instead of refs

* implement a pricing display api with session passing

* moved middleware to proxy according to new changes in Nextjs

* refactoed kafka ingestion to go via backend not web-db

* Refactor docker-compose services to use individual Dockerfiles (#20)

* Initial plan

* Refactor services into individual Dockerfiles

Co-authored-by: velocitatem <60182044+velocitatem@users.noreply.github.com>

* Add EXPOSE directives to all Dockerfiles with port documentation

Co-authored-by: velocitatem <60182044+velocitatem@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: velocitatem <60182044+velocitatem@users.noreply.github.com>

* fixing small bugs and adding exepriments to tracking

* added some doc

.env.example

@@ -1,5 +1,18 @@
-HOSTNAME=localhost
+# Network configuration
+HOSTNAME=localhost  # hostname for service discovery across docker network
 
-# PORTS
-KAFKA_PORT=9092
-REDIS_PORT=6377
+# Application configuration
+STORE_MODE=hotel  # platform mode: 'hotel' or 'airline' - determines product catalog and UI theme
+NEXT_PUBLIC_API_BASE=http://localhost:3000  # base URL for API endpoints, must be valid URL format
+NEXT_PUBLIC_APP_ENV=dev  # application environment: 'dev' or 'prod' - controls logging, error handling
+NEXT_PUBLIC_HOVER_THRESHOLD=1200  # hover threshold in milliseconds for UI interactions
+
+# Backend service
+BACKEND_URL=http://localhost:5000  # backend API URL for kafka ingestion (set to railway service URL in prod)
+
+# Service ports - used by docker-compose and service communication
+BACKEND_PORT=5000  # backend server port for kafka ingestion API
+KAFKA_HOST=localhost  # kafka broker hostname - set to remote host in prod (e.g., kafka.example.com)
+KAFKA_PORT=9092  # kafka broker port for event streaming
+REDIS_PORT=6377  # redis port for worker queue and caching
+REDPANDA_CONSOLE_PORT=8084  # redpanda console UI port for kafka monitoring

.github/workflows/pytest.yml

@@ -0,0 +1,30 @@
+name: Run Tests
+on:
+  push:
+    paths:
+      - 'experiments/**'
+      - 'backend/**'
+      - 'requirements.txt'
+      - '.github/workflows/pytest.yml'
+  pull_request:
+    paths:
+      - 'experiments/**'
+      - 'backend/**'
+      - 'requirements.txt'
+      - '.github/workflows/pytest.yml'
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+      - name: Install dependencies
+        run: |
+          python -m venv .venv
+          .venv/bin/pip install --upgrade pip
+          .venv/bin/pip install -r requirements.txt
+      - name: Run tests
+        run: .venv/bin/pytest -v

.gitignore

@@ -1,2 +1,8 @@
 **/.env
-**/.venv
+**/.venv
+**/__pycache__
+**/.ipynb_checkpoints/
+**/.virtual_documents/
+**/session_*.svg
+**/*graph.svg
+paper/src/bib/auto

Makefile

@@ -4,6 +4,10 @@ BUILDDIR  := build
 TEX       := main.tex
 JOBNAME   := main
 PDF       := paper/$(BUILDDIR)/$(JOBNAME).pdf
+VENV      := .venv
+PYTHON    := $(VENV)/bin/python
+PIP       := $(VENV)/bin/pip
+PYTEST    := $(VENV)/bin/pytest
 
 .DEFAULT_GOAL := help
 
@@ -35,5 +39,14 @@ clean:
 	$(LATEXMK) -C -jobname=$(JOBNAME) -outdir=../$(BUILDDIR) || true
 	rm -rf paper/$(BUILDDIR)/*
 
+$(VENV):
+	python3 -m venv $(VENV)
+	$(PIP) install --upgrade pip
 
-.PHONY: all pdf clean watch run.webapp
+install: $(VENV)
+	$(PIP) install -r requirements.txt
+
+test: $(VENV)
+	$(PYTEST) -v
+
+.PHONY: all pdf clean watch run.webapp install test

README.md

@@ -1 +1,5 @@
 [![Build PDF](https://github.com/velocitatem/PHANTOM/actions/workflows/latex.yml/badge.svg)](https://github.com/velocitatem/PHANTOM/actions/workflows/latex.yml)
+
+- https://phantom-hotel.vercel.app/
+- https://phantom-airline.vercel.app/
+

backend/server/app.py

@@ -0,0 +1,189 @@
+# boilerplate code
+from fastapi import FastAPI, HTTPException
+from fastapi.middleware.cors import CORSMiddleware
+from pydantic import BaseModel
+from typing import Optional, Any
+import uvicorn
+import os
+import json
+from datetime import datetime
+from kafka import KafkaProducer, KafkaAdminClient, KafkaConsumer
+from kafka.admin import NewTopic
+from kafka.errors import TopicAlreadyExistsError
+from dotenv import load_dotenv
+load_dotenv()
+
+app = FastAPI()
+
+# kafka producer - lazy init
+_producer: Optional[KafkaProducer] = None
+
+def get_producer() -> KafkaProducer:
+    global _producer
+    if _producer is None:
+        host = os.getenv('KAFKA_HOST', 'localhost')
+        port = os.getenv('KAFKA_PORT', '9092')
+        broker = f'{host}:{port}' if port else host
+        print(f"[KAFKA_INIT] Connecting to broker: {broker}")
+        _producer = KafkaProducer(
+            bootstrap_servers=[broker],
+            value_serializer=lambda v: json.dumps(v).encode('utf-8'),
+            key_serializer=lambda k: k.encode('utf-8') if k else None,
+            acks=1,
+            retries=3,
+            max_in_flight_requests_per_connection=5,
+            request_timeout_ms=30000,
+            api_version_auto_timeout_ms=10000,
+            max_block_ms=5000,  # don't block send() for more than 5s
+        )
+        print(f"[KAFKA_INIT] Producer created successfully")
+    return _producer
+
+class EventPayload(BaseModel):
+    sessionId: str
+    eventName: str
+    page: str
+    productId: Optional[str] = None
+    metadata: Optional[dict[str, Any]] = None
+    storeMode: str
+    userAgent: Optional[str] = None
+    ts: Optional[str] = None
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+@app.on_event("startup")
+async def startup_event():
+    """create kafka topics on startup"""
+    host = os.getenv('KAFKA_HOST', 'localhost')
+    port = os.getenv('KAFKA_PORT', '9092')
+    broker = f'{host}:{port}'
+
+    try:
+        print(f"[STARTUP] Creating Kafka topics on {broker}")
+        admin = KafkaAdminClient(
+            bootstrap_servers=[broker],
+            request_timeout_ms=10000,
+        )
+
+        topics = [
+            NewTopic(name='user-interactions', num_partitions=3, replication_factor=1)
+        ]
+
+        admin.create_topics(new_topics=topics, validate_only=False)
+        print(f"[STARTUP] Topics created successfully")
+        admin.close()
+    except TopicAlreadyExistsError:
+        print(f"[STARTUP] Topics already exist, skipping creation")
+    except Exception as e:
+        print(f"[STARTUP] Failed to create topics: {e}")
+        print(f"[STARTUP] Will rely on auto-creation on first message")
+
+@app.get("/health")
+async def health():
+    kafka_status = "unknown"
+    try:
+        producer = get_producer()
+        # attempt to get cluster metadata to verify connection
+        producer.bootstrap_connected()
+        kafka_status = "connected"
+    except Exception as e:
+        kafka_status = f"error: {str(e)}"
+
+    return {
+        "status": "healthy",
+        "kafka": kafka_status,
+        "kafka_broker": f"{os.getenv('KAFKA_HOST', 'localhost')}:{os.getenv('KAFKA_PORT', '9092')}"
+    }
+
+
+@app.post("/api/kafka/ingest")
+async def ingest_logs(event: EventPayload):
+    try:
+        if not event.ts:
+            event.ts = datetime.utcnow().isoformat() + 'Z'
+
+        producer = get_producer()
+        future = producer.send(
+            'user-interactions',
+            key=event.sessionId,
+            value=event.model_dump()
+        )
+        # add callback for error logging but don't block
+        future.add_errback(lambda e: print(f"[KAFKA_SEND_ERROR] {e}"))
+
+        return {"success": True}
+    except Exception as e:
+        import traceback
+        print(f"[ERROR] {e}")
+        print(traceback.format_exc())
+        raise HTTPException(status_code=500, detail=str(e))
+
+@app.get("/api/kafka/dump")
+def dump_logs(
+    last_n: Optional[int] = None,
+    t_start: Optional[str] = None,
+    t_end: Optional[str] = None
+):
+    """dump all messages from user-interactions topic
+
+    params:
+        last_n: return only last n messages (default: all)
+        t_start: filter by start timestamp iso format (future use)
+        t_end: filter by end timestamp iso format (future use)
+    """
+    host = os.getenv('KAFKA_HOST', 'localhost')
+    port = os.getenv('KAFKA_PORT', '9092')
+    broker = f'{host}:{port}'
+
+    try:
+        consumer = KafkaConsumer(
+            'user-interactions',
+            bootstrap_servers=[broker],
+            auto_offset_reset='earliest',
+            enable_auto_commit=False,
+            value_deserializer=lambda x: json.loads(x.decode('utf-8')),
+            consumer_timeout_ms=5000
+        )
+
+        events = []
+        for msg in consumer:
+            events.append(msg.value)
+
+        consumer.close()
+
+        # apply filters
+        if t_start or t_end:
+            # filter by timestamp range if provided
+            filtered = []
+            for e in events:
+                ts = e.get('ts')
+                if ts:
+                    if t_start and ts < t_start:
+                        continue
+                    if t_end and ts > t_end:
+                        continue
+                filtered.append(e)
+            events = filtered
+
+        if last_n and last_n > 0:
+            events = events[-last_n:]
+
+        return {"success": True, "count": len(events), "data": events}
+
+    except Exception as e:
+        import traceback
+        print(f"[DUMP_ERROR] {e}")
+        print(traceback.format_exc())
+        raise HTTPException(status_code=500, detail=str(e))
+
+
+
+if __name__ == "__main__":
+    PORT=int(os.getenv("BACKEND_PORT", 5000))
+    uvicorn.run("server:app", host="0.0.0.0", port=PORT, reload=True)

backend/server/requirements.txt

@@ -0,0 +1,5 @@
+fastapi==0.104.1
+uvicorn[standard]==0.24.0
+kafka-python==2.0.2
+pydantic==2.5.0
+python-dotenv==1.0.0

docker-compose.yml

@@ -1,4 +1,18 @@
 services:
+  backend:
+    container_name: "PHANTOM-backend"
+    build:
+      context: .
+      dockerfile: docker/backend.Dockerfile
+    ports:
+      - "${BACKEND_PORT:-5000}:5000"
+    environment:
+      - KAFKA_HOST=kafka
+      - KAFKA_PORT=29092
+    depends_on:
+      - kafka
+    restart: unless-stopped
+
   redis:
     container_name: "PHANTOM-redis"
     build:
@@ -9,6 +23,7 @@ services:
     volumes:
       - phantom_redis_data:/data
     restart: unless-stopped
+
   zookeeper:
     container_name: "PHANTOM-zookeeper"
     build:

docker/backend.Dockerfile

@@ -0,0 +1,12 @@
+FROM python:3.11-slim
+
+WORKDIR /app
+
+COPY backend/server/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY backend/server/app.py .
+
+EXPOSE 5000
+
+CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "5000"]

experiments/agents/__init__.py

@@ -0,0 +1 @@
+"""Agentic behavior runner for PHANTOM research platform."""

experiments/agents/agent.py

@@ -0,0 +1,44 @@
+from .base import Agent as BaseAgent
+from browser_use import Browser, Agent, ChatOpenAI
+from enum import Enum
+
+class AgentTypes(str, Enum):
+    GENERIC_BROWSER_USE_AGENT = "generic_browser_use_agent"
+
+def _build_prompt(goal : str, environment_url : str) -> str:
+    #TODO: Improve prompt engineering here and experiment with
+    return f"""You are an autonomous agent tasked with achieving the following goal: {goal}
+You have access to a web browser to interact with the environment at {environment_url}.
+Use the browser to navigate, gather information, and perform actions necessary to accomplish your goal.
+Be thorough and ensure you complete the task fully."""
+
+class GenericBrowserUseAgent(BaseAgent):
+    def __init__(self,
+                 goal: str,
+                 url: str = "http://localhost:3000",
+                 timeout: int = 300,
+                 llm_model: str = "gpt-5-mini",
+                 headless: bool = True):
+        super().__init__(goal, url, timeout)
+        self.llm_model = ChatOpenAI(model=llm_model)
+        self.browser = Browser(headless=headless)
+        self.agent = Agent(task=_build_prompt(goal, url),
+                           llm=self.llm_model,
+                           browser=self.browser)
+    async def act(self) -> str:
+        self.result = await self.agent.run()
+        # https://github.com/browser-use/browser-use/blob/main/browser_use/agent/views.py#L301
+        return self.result.final_result()
+
+def get_agent(agent_type: AgentTypes,  **kwargs) -> Agent:
+    if agent_type == AgentTypes.GENERIC_BROWSER_USE_AGENT:
+        return GenericBrowserUseAgent(**kwargs)
+    else:
+        raise ValueError(f"Unknown agent type: {agent_type}")
+
+if __name__ == "__main__":
+    import asyncio
+    JTBD= "Name all the products on this site and try to find out more about each product by clicking into them (they might not open)"
+    agent = get_agent(AgentTypes.GENERIC_BROWSER_USE_AGENT, goal=JTBD, url="http://localhost:3000/products", timeout=300)
+    R=asyncio.run(agent.act())
+    print(R)

experiments/agents/base.py

@@ -0,0 +1,19 @@
+from abc import ABC, abstractmethod
+from typing import Optional
+
+class Agent(ABC):
+    """Base interface for browser automation agents"""
+
+    def __init__(self, goal: str, url: str = "http://localhost:3000", timeout: int = 300):
+        self.goal = goal
+        self.url = url
+        self.timeout = timeout
+        self.result: Optional[str] = None
+
+    @abstractmethod
+    async def act(self) -> str:
+        """Execute goal and return result text"""
+        pass
+
+    def final_result(self) -> Optional[str]:
+        return self.result

experiments/agents/test.py

@@ -0,0 +1,30 @@
+import pytest
+import asyncio
+from experiments.agents.agent import get_agent, AgentTypes
+import os
+
+
+def test_agent_init():
+    agent = get_agent(AgentTypes.GENERIC_BROWSER_USE_AGENT, goal="test", url="http://example.com", timeout=100)
+    assert agent.goal == "test"
+    assert agent.url == "http://example.com"
+    assert agent.timeout == 100
+
+
+def test_invalid_agent():
+    with pytest.raises(ValueError):
+        get_agent("invalid", goal="test")
+
+
+@pytest.mark.asyncio
+@pytest.mark.skipif("OPENAI_API_KEY" not in os.environ, reason="OPENAI_API_KEY not set")
+async def test_agent_execution():
+    agent = get_agent(AgentTypes.GENERIC_BROWSER_USE_AGENT, goal="get page title", url="https://example.com", timeout=60)
+
+    result = await agent.act()
+    assert result
+    assert agent.final_result()
+    assert agent.final_result().history[-1].result[-1].is_done == True
+    assert isinstance(result, str)
+    assert "example" in result.lower()
+    assert len(result) > 0

experiments/procesing/extract.py

@@ -0,0 +1,84 @@
+import pandas as pd
+import json
+import numpy as np
+import os
+import requests
+from dotenv import load_dotenv
+from sklearn.base import BaseEstimator, TransformerMixin
+load_dotenv()
+
+BACKEND_URL = os.getenv("BACKEND_URL", "http://localhost:5000")
+N_PRICE_BUCKETS = 5
+
+def get_data_from_kafka() -> pd.DataFrame:
+    """fetch all events from backend dump endpoint"""
+    resp = requests.get(f"{BACKEND_URL}/api/kafka/dump")
+    resp.raise_for_status()
+    data = resp.json()
+
+    if not data.get('success') or not data.get('data'):
+        return pd.DataFrame()
+
+    df = pd.DataFrame(data['data'])
+    # explode metadata col json
+    if 'metadata' in df.columns:
+        df = df.join(pd.json_normalize(df.pop("metadata"), sep=".").add_prefix("metadata_"))
+    df = df.dropna(subset=['eventName'])
+    return df
+
+
+def join_with_experiments(df: pd.DataFrame) -> pd.DataFrame:
+    # TODO: Get experiments db from supabase and join on session_id
+    return df
+
+
+def augment_event_titles(df: pd.DataFrame) -> pd.DataFrame:
+    # from taking standard view_item_page in eventName to view_item_page_{metadata_schema}
+    # we want metadata schema to create product specific event names
+
+    # only create price buckets if we have enough unique prices
+    if df["metadata_price"].notnull().sum() > 0:
+        try:
+            price_buckets = pd.qcut(
+                df["metadata_price"],
+                q=N_PRICE_BUCKETS,
+                labels=[f"PB_{i+1}" for i in range(N_PRICE_BUCKETS)],
+                duplicates='drop'  # handle duplicate bin edges
+            )
+        except ValueError:
+            # fallback: if still not enough unique values, use cut with fixed ranges or just use raw price
+            price_buckets = df["metadata_price"].apply(lambda x: f"P_{int(x)}" if pd.notnull(x) else "")
+    else:
+        price_buckets = pd.Series([""] * len(df), index=df.index)
+
+    # metadata_schema: _product_id@price_bucket_{i} only if we have product metadata otherswise keep original event name
+    # TODO: make this adaptive, if we have hover_over_title we append the title, if its view_page we say which page
+    df["metadata_schema"] = np.where(
+        df["productId"].notnull() & df["metadata_price"].notnull(),
+        "_" + df["productId"].astype(str) + "@" + price_buckets.astype(str),
+        ""
+    )
+    df["eventName"] = df["eventName"] + df["metadata_schema"].astype(str)
+    return df
+
+
+def extract() -> pd.DataFrame:
+    df = get_data_from_kafka()
+    df = join_with_experiments(df)
+    df = augment_event_titles(df)
+    return df
+
+
+class DataExtractor(BaseEstimator, TransformerMixin):
+    def fit(self, X=None, y=None):
+        return self
+
+    def transform(self, X=None):
+        return extract()
+
+
+if __name__ == "__main__":
+    df = extract()
+    print(df.head())
+    print(df.tail())
+    print(df.info())

experiments/procesing/mapping.py

@@ -0,0 +1,158 @@
+import numpy as np
+import pandas as pd
+from sklearn.base import BaseEstimator, TransformerMixin
+
+def build_transition_prob_matrix(df: pd.DataFrame):
+    df = df.dropna(subset=['eventName'])
+    events = df['eventName'].tolist()
+    labels = pd.Index(events).unique().tolist()
+    idx = {e:i for i,e in enumerate(labels)}
+    M = np.zeros((len(labels), len(labels)), dtype=float)
+    for a, b in zip(events, events[1:]):
+        M[idx[a], idx[b]] += 1
+    row_sums = M.sum(axis=1, keepdims=True)
+    with np.errstate(divide='ignore', invalid='ignore'):
+        P = np.divide(M, row_sums, where=row_sums>0)  # row-normalized
+    return P, labels
+
+# https://medium.com/data-science/time-series-data-markov-transition-matrices-7060771e362b
+from graphviz import Digraph
+import numpy as np
+import pandas as pd
+
+def _as_prob_df(matrix, labels=None):
+    """Return a square DataFrame with index=columns=labels."""
+    if isinstance(matrix, pd.DataFrame):
+        # Ensure square and aligned
+        assert (matrix.index == matrix.columns).all(), "Index/columns must match."
+        return matrix
+    matrix = np.asarray(matrix, dtype=float)
+    assert matrix.shape[0] == matrix.shape[1], "Matrix must be square."
+    if labels is None:
+        raise ValueError("labels are required when matrix is not a DataFrame")
+    assert len(labels) == matrix.shape[0], "labels length must match matrix size."
+    return pd.DataFrame(matrix, index=list(labels), columns=list(labels))
+
+def _df_to_edgelist(P: pd.DataFrame, threshold=0.0, round_digits=2):
+    """Build weighted edges > threshold."""
+    edges = []
+    for src in P.index:
+        for dst in P.columns:
+            w = float(P.loc[src, dst])
+            if w > threshold:
+                edges.append((str(src), str(dst), f"{w:.{round_digits}f}"))
+    return edges
+
+def render_graph(fname, matrix, ls_index=None, threshold=0.0, fmt="svg", view=False):
+    """
+    fname: output file stem (no extension)
+    matrix: NumPy array or pandas DataFrame of transition PROBABILITIES
+    ls_index: ordered labels (required if matrix is not a DataFrame)
+    threshold: hide edges with weight <= threshold
+    fmt: 'svg'|'png'|'pdf' etc.
+    view: open after rendering
+    """
+    P = _as_prob_df(matrix, labels=ls_index)
+    edges = _df_to_edgelist(P, threshold=threshold)
+
+    g = Digraph(format=fmt)
+    g.attr(rankdir="LR", size="30")
+    g.attr("node", shape="circle")
+
+    # ensure isolated nodes appear
+    for node in P.index:
+        g.node(str(node), width="1", height="1")
+
+    for src, dst, label in edges:
+        g.edge(src, dst, label=label)
+
+    g.render(fname, view=view, cleanup=True)
+    return g
+
+
+class TransitionProbMatrixTransformer(BaseEstimator, TransformerMixin):
+    def __init__(self, threshold=0.0):
+        self.threshold = threshold
+        self.P_ = None
+        self.labels_ = None
+
+    def fit(self, X: pd.DataFrame, y=None):
+        P, labels = build_transition_prob_matrix(X)
+        self.P_ = P
+        self.labels_ = labels
+        return self
+
+    def transform(self, X: pd.DataFrame = None):
+        return self.P_, self.labels_
+
+    def render(self, fname: str, fmt="svg", view=False):
+        if self.P_ is None or self.labels_ is None:
+            raise ValueError("Transformer has not been fitted yet.")
+        return render_graph(
+            fname,
+            self.P_,
+            ls_index=self.labels_,
+            threshold=self.threshold,
+            fmt=fmt,
+            view=view
+        )
+
+
+class SessionTransitionProbMatrixTransformer(BaseEstimator, TransformerMixin):
+    def __init__(self, threshold=0.0, session_col='sessionId'):
+        self.threshold = threshold
+        self.session_col = session_col
+        self.session_matrices_ = None
+
+    def fit(self, X: pd.DataFrame, y=None):
+        if self.session_col not in X.columns:
+            raise ValueError(f"Column '{self.session_col}' not found in DataFrame")
+
+        session_matrices = {}
+        for session_id, grp in X.groupby(self.session_col):
+            if len(grp) > 1:  # need at least 2 events for transitions
+                P, labels = build_transition_prob_matrix(grp)
+                session_matrices[session_id] = {'matrix': P, 'labels': labels}
+
+        self.session_matrices_ = session_matrices
+        return self
+
+    def transform(self, X: pd.DataFrame = None):
+        if self.session_matrices_ is None:
+            raise ValueError("Transformer has not been fitted yet.")
+        return pd.Series(self.session_matrices_)
+
+    def render_session(self, session_id: str, fname: str, fmt="svg", view=False):
+        if self.session_matrices_ is None:
+            raise ValueError("Transformer has not been fitted yet.")
+        if session_id not in self.session_matrices_:
+            raise ValueError(f"Session '{session_id}' not found in fitted data.")
+
+        sess_data = self.session_matrices_[session_id]
+        return render_graph(
+            fname,
+            sess_data['matrix'],
+            ls_index=sess_data['labels'],
+            threshold=self.threshold,
+            fmt=fmt,
+            view=view
+        )
+if __name__ == "__main__":
+    # Example usage
+    data = {
+        'eventName': [
+            'A', 'B', 'A', 'C', 'B', 'A', 'A', 'C', 'B', 'C',
+            'A', 'B', 'C', 'A', 'B', 'C', 'A', 'B', 'C', 'A'
+        ]
+    }
+    df = pd.DataFrame(data)
+
+    transformer = TransitionProbMatrixTransformer(threshold=0.1)
+    transformer.fit(df)
+    P, labels = transformer.transform(None)
+
+    print("Transition Probability Matrix:")
+    print(pd.DataFrame(P, index=labels, columns=labels))
+
+    # Render the graph
+    transformer.render("transition_graph", fmt="svg", view=False)

experiments/procesing/pipeline.py

@@ -0,0 +1,19 @@
+from sklearn.pipeline import Pipeline
+from sklearn.preprocessing import StandardScaler
+from extract import DataExtractor
+from mapping import SessionTransitionProbMatrixTransformer, render_graph
+
+
+if __name__ == "__main__":
+    steps = [
+        ('data_extraction', DataExtractor()),
+        ('transition_matrix', SessionTransitionProbMatrixTransformer(threshold=0.05)),
+    ]
+    pipeline = Pipeline(steps)
+    result = pipeline.fit_transform(None)
+    print(f"Number of sessions: {len(result)}\n")
+
+    for session_id, sess_data in result.items():
+        fname = f"session_{session_id}"
+        render_graph(fname, sess_data['matrix'], ls_index=sess_data['labels'], threshold=0.05, fmt="svg", view=False)
+        print(f"Rendered {fname}.svg")

paper/concat_code.sh

@@ -16,10 +16,11 @@ mkdir -p "$(dirname "$OUTPUT_FILE")"
 add_file() {
     local filepath="$1"
     local relpath="${filepath#$PROJECT_ROOT/}"
+    local escaped_path="${relpath//_/\\_}"
 
     # Add section header and code listing (no language-specific highlighting)
-    echo "\\subsection{${relpath}}" >> "$OUTPUT_FILE"
-    echo "\\begin{lstlisting}[caption={${relpath}}]" >> "$OUTPUT_FILE"
+    echo "\\subsection{${escaped_path}}" >> "$OUTPUT_FILE"
+    echo "\\begin{lstlisting}[caption={${escaped_path}}]" >> "$OUTPUT_FILE"
     cat "$filepath" >> "$OUTPUT_FILE"
     echo "" >> "$OUTPUT_FILE"
     echo "\\end{lstlisting}" >> "$OUTPUT_FILE"

paper/src/preamble.tex

@@ -20,7 +20,10 @@
     commentstyle=\color{green!60!black},
     stringstyle=\color{red},
     showstringspaces=false,
-    captionpos=b
+    captionpos=b,
+    inputencoding=utf8,
+    extendedchars=true,
+    literate={·}{{\textperiodcentered}}1 {−}{{\textminus}}1 {—}{{---}}1 {–}{{--}}1
 }
 
 % Use biblatex instead of natbib (acmart default)

pytest.ini

@@ -0,0 +1,7 @@
+[pytest]
+testpaths = experiments
+python_files = test*.py
+python_classes = Test*
+python_functions = test_*
+asyncio_mode = auto
+asyncio_default_fixture_loop_scope = function

requirements.txt

@@ -5,3 +5,8 @@ jupyter
 ipykernel
 matplotlib
 graphviz
+browser-use
+pytest
+pytest-asyncio
+uv
+scikit-learn

web/README.md

@@ -12,3 +12,86 @@ The webapp should serve under the / route the landing page which for both platfo
 - /app will have (airline) and (hotel) children which each have a layout.tsx and page.tsx where /app also has a parent layout defining layout.tsx and globals.css for any shared styling to avoid repretition.
 - /components/ is gonna have ui/ which defines things like Button, Card, DatePicker with generic definitions and any tracking or observation code. We then define feats/airline/ and feats/hotel/ as children of components with specific components like AirlineHero and HotelCard.
 - in /styles/ we define airline.css and hotel.css to tailor accents and styling for each.
+
+## How to Run
+
+```sh
+# install deps
+npm install
+
+# set store mode (hotel or airline)
+export STORE_MODE=hotel
+
+# run dev server
+npm run dev
+```
+
+Server runs on `http://localhost:3000`
+
+## Environment Variables
+
+| Variable | Description | Default | Example |
+|----------|-------------|---------|---------|
+| `HOSTNAME` | Server hostname | `localhost` | `localhost` |
+| `STORE_MODE` | Mode switch for platform | `hotel` | `hotel` or `airline` |
+| `NEXT_PUBLIC_API_BASE` | Public API base URL | `http://localhost:3000` | `http://localhost:3000` |
+| `NEXT_PUBLIC_APP_ENV` | Application environment | `dev` | `dev`, `prod` |
+| `NEXT_PUBLIC_HOVER_THRESHOLD` | Hover dwell threshold (ms) | `1200` | `1200` |
+| `BACKEND_URL` | Backend service URL | `http://localhost:5000` | `http://localhost:5000` |
+
+## Routes
+
+### Public Pages
+- `/` — Landing page (mode-aware root)
+- `/hotel` — Hotel mode landing
+- `/hotel/products` — Hotel catalog
+- `/airline` — Airline mode landing
+- `/airline/products` — Flight catalog
+- `/admin/experiments` — Experiment management UI
+
+### API Routes
+- `GET /api/session` — Fetch or create session, sets httpOnly cookie
+- `GET /api/pricing?productId=X&sessionId=Y&experimentId=Z` — Get product price from provider
+- `POST /api/ingest` — Ingest event to Kafka via backend
+- `GET /api/admin/experiments` — List all experiments
+- `POST /api/admin/experiments/start` — Start new experiment for session
+- `POST /api/admin/experiments/stop` — Stop experiment by ID
+
+## Event Catalog
+
+All events are ingested via `POST /api/ingest` and follow the `EventBase` schema. Below are the 17 canonical events:
+
+| Event Name | Category | Payload Example |
+|------------|----------|-----------------|
+| `session_start` | Session | `{ sessionId, experimentId?, storeMode, ts, page, eventName, userAgent? }` |
+| `page_view` | Navigation | `{ sessionId, experimentId?, storeMode, ts, page: "/hotel", eventName: "page_view" }` |
+| `view_item_page` | Discovery | `{ sessionId, storeMode, ts, page: "/hotel/products", productId: "H001", eventName: "view_item_page" }` |
+| `learn_more_about_item` | Discovery | `{ sessionId, storeMode, ts, page, productId, eventName: "learn_more_about_item" }` |
+| `add_item_to_cart` | Cart | `{ sessionId, storeMode, ts, page, productId, eventName: "add_item_to_cart" }` |
+| `remove_item` | Cart | `{ sessionId, storeMode, ts, page, productId, eventName: "remove_item" }` |
+| `checkout_start` | Cart | `{ sessionId, storeMode, ts, page, eventName: "checkout_start" }` |
+| `purchase_complete` | Cart | `{ sessionId, storeMode, ts, page, eventName: "purchase_complete", metadata?: { total: 500 } }` |
+| `search` | Filter/Search | `{ sessionId, storeMode, ts, page, eventName: "search", metadata: { query: "paris" } }` |
+| `filter_for_date` | Filter/Search | `{ sessionId, storeMode, ts, page, eventName: "filter_for_date", metadata: { from: "2025-01-15", to: "2025-01-20" } }` |
+| `filter_for_amenities` | Filter/Search | `{ sessionId, storeMode, ts, page, eventName: "filter_for_amenities", metadata: { amenities: ["wifi", "pool"] } }` |
+| `filter_for_price` | Filter/Search | `{ sessionId, storeMode, ts, page, eventName: "filter_for_price", metadata: { min: 100, max: 500 } }` |
+| `sort_change` | Filter/Search | `{ sessionId, storeMode, ts, page, eventName: "sort_change", metadata: { sort: "price_asc" } }` |
+| `hover_over_title` | Dwell signal | `{ sessionId, storeMode, ts, page, productId?, eventName: "hover_over_title", metadata: { duration: 1500 } }` |
+| `hover_over_paragraph` | Dwell signal | `{ sessionId, storeMode, ts, page, productId?, eventName: "hover_over_paragraph", metadata: { duration: 2000 } }` |
+| `hover_over_link` | Dwell signal | `{ sessionId, storeMode, ts, page, productId?, eventName: "hover_over_link", metadata: { href: "/hotel/products" } }` |
+| `hover_over_button` | Dwell signal | `{ sessionId, storeMode, ts, page, productId?, eventName: "hover_over_button", metadata: { label: "Book Now" } }` |
+
+## Architecture
+
+### Route Groups
+- `(hotel)` — Hotel mode pages
+- `(airline)` — Airline mode pages
+- `api/*` — API routes (session, pricing, ingest, admin)
+
+### Middleware Flow
+1. Request arrives at Next.js
+2. Session middleware checks for `phantom_session_id` cookie
+3. If missing, `/api/session` mints new session + sets cookie
+4. Store mode (`STORE_MODE` env) determines rendered page variant
+5. Client-side components fetch pricing via `/api/pricing`
+6. User interactions emit events to `/api/ingest` → Kafka

web/package-lock.json

@@ -8,10 +8,10 @@
       "name": "web",
       "version": "0.1.0",
       "dependencies": {
-        "kafkajs": "^2.2.4",
         "next": "16.0.0",
         "react": "19.2.0",
-        "react-dom": "19.2.0"
+        "react-dom": "19.2.0",
+        "zod": "^4.1.12"
       },
       "devDependencies": {
         "@tailwindcss/postcss": "^4",
@@ -1041,15 +1041,6 @@
         "jiti": "lib/jiti-cli.mjs"
       }
     },
-    "node_modules/kafkajs": {
-      "version": "2.2.4",
-      "resolved": "https://registry.npmjs.org/kafkajs/-/kafkajs-2.2.4.tgz",
-      "integrity": "sha512-j/YeapB1vfPT2iOIUn/vxdyKEuhuY2PxMBvf5JWux6iSaukAccrMtXEY/Lb7OvavDhOWME589bpLrEdnVHjfjA==",
-      "license": "MIT",
-      "engines": {
-        "node": ">=14.0.0"
-      }
-    },
     "node_modules/lightningcss": {
       "version": "1.30.2",
       "resolved": "https://registry.npmjs.org/lightningcss/-/lightningcss-1.30.2.tgz",
@@ -1616,6 +1607,15 @@
       "integrity": "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==",
       "dev": true,
       "license": "MIT"
+    },
+    "node_modules/zod": {
+      "version": "4.1.12",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-4.1.12.tgz",
+      "integrity": "sha512-JInaHOamG8pt5+Ey8kGmdcAcg3OL9reK8ltczgHTAwNhMys/6ThXHityHxVV2p3fkw/c+MAvBHFVYHFZDmjMCQ==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/colinhacks"
+      }
     }
   }
 }

web/package.json

@@ -8,10 +8,10 @@
     "start": "next start"
   },
   "dependencies": {
-    "kafkajs": "^2.2.4",
     "next": "16.0.0",
     "react": "19.2.0",
-    "react-dom": "19.2.0"
+    "react-dom": "19.2.0",
+    "zod": "^4.1.12"
   },
   "devDependencies": {
     "@tailwindcss/postcss": "^4",

web/src/app/admin/experiments/page.tsx

@@ -0,0 +1,199 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import { useSession } from '@/hooks/useSession';
+
+type Experiment = {
+  id: string;
+  status: 'active' | 'stopped';
+  sessionIds: string[];
+  createdAt: number;
+};
+
+export default function ExperimentsAdmin() {
+  const { sessionId, isLoading: sessionLoading } = useSession();
+  const [exps, setExps] = useState<Experiment[]>([]);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const fetchExps = async () => {
+    try {
+      const res = await fetch('/api/admin/experiments');
+      if (!res.ok) throw new Error(`fetch failed: ${res.status}`);
+      const data = await res.json();
+      setExps(data.experiments || []);
+    } catch (err: any) {
+      setError(err.message);
+    }
+  };
+
+  useEffect(() => {
+    fetchExps();
+  }, []);
+
+  const handleStart = async () => {
+    if (!sessionId) {
+      setError('no session available');
+      return;
+    }
+
+    setLoading(true);
+    setError(null);
+
+    try {
+      const res = await fetch('/api/admin/experiments/start', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ sessionId }),
+      });
+
+      if (!res.ok) {
+        const data = await res.json();
+        throw new Error(data.error || 'start failed');
+      }
+
+      await fetchExps(); // refresh list
+    } catch (err: any) {
+      setError(err.message);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  const handleStop = async (expId: string) => {
+    setLoading(true);
+    setError(null);
+
+    try {
+      const res = await fetch('/api/admin/experiments/stop', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ experimentId: expId }),
+      });
+
+      if (!res.ok) {
+        const data = await res.json();
+        throw new Error(data.error || 'stop failed');
+      }
+
+      await fetchExps(); // refresh list
+    } catch (err: any) {
+      setError(err.message);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  if (sessionLoading) {
+    return (
+      <div className="flex min-h-screen items-center justify-center bg-zinc-50 dark:bg-black">
+        <p className="text-zinc-600 dark:text-zinc-400">loading session...</p>
+      </div>
+    );
+  }
+
+  return (
+    <div className="min-h-screen bg-zinc-50 px-6 py-12 dark:bg-black">
+      <div className="mx-auto max-w-5xl">
+        <div className="mb-8 flex items-center justify-between">
+          <div>
+            <h1 className="text-3xl font-semibold tracking-tight text-black dark:text-zinc-50">
+              Experiments
+            </h1>
+            <p className="mt-2 text-sm text-zinc-600 dark:text-zinc-400">
+              current session: {sessionId || 'none'}
+            </p>
+          </div>
+          <button
+            onClick={handleStart}
+            disabled={loading || !sessionId}
+            className="rounded-lg bg-black px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-zinc-800 disabled:opacity-50 dark:bg-zinc-50 dark:text-black dark:hover:bg-zinc-200"
+          >
+            {loading ? 'starting...' : 'start experiment'}
+          </button>
+        </div>
+
+        {error && (
+          <div className="mb-4 rounded-lg bg-red-50 p-4 text-sm text-red-800 dark:bg-red-950 dark:text-red-200">
+            {error}
+          </div>
+        )}
+
+        <div className="overflow-hidden rounded-lg border border-zinc-200 bg-white dark:border-zinc-800 dark:bg-zinc-950">
+          <table className="w-full text-left text-sm">
+            <thead className="border-b border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-900">
+              <tr>
+                <th className="px-6 py-3 font-medium text-zinc-900 dark:text-zinc-100">
+                  experiment id
+                </th>
+                <th className="px-6 py-3 font-medium text-zinc-900 dark:text-zinc-100">
+                  status
+                </th>
+                <th className="px-6 py-3 font-medium text-zinc-900 dark:text-zinc-100">
+                  session count
+                </th>
+                <th className="px-6 py-3 font-medium text-zinc-900 dark:text-zinc-100">
+                  created
+                </th>
+                <th className="px-6 py-3 font-medium text-zinc-900 dark:text-zinc-100">
+                  action
+                </th>
+              </tr>
+            </thead>
+            <tbody className="divide-y divide-zinc-200 dark:divide-zinc-800">
+              {exps.length === 0 ? (
+                <tr>
+                  <td
+                    colSpan={5}
+                    className="px-6 py-8 text-center text-zinc-500 dark:text-zinc-400"
+                  >
+                    no experiments yet
+                  </td>
+                </tr>
+              ) : (
+                exps.map((exp) => (
+                  <tr
+                    key={exp.id}
+                    className="hover:bg-zinc-50 dark:hover:bg-zinc-900"
+                  >
+                    <td className="px-6 py-4 font-mono text-xs text-zinc-700 dark:text-zinc-300">
+                      {exp.id.slice(0, 8)}...
+                    </td>
+                    <td className="px-6 py-4">
+                      <span
+                        className={`inline-block rounded-full px-2 py-1 text-xs font-medium ${
+                          exp.status === 'active'
+                            ? 'bg-green-100 text-green-800 dark:bg-green-950 dark:text-green-200'
+                            : 'bg-zinc-100 text-zinc-800 dark:bg-zinc-800 dark:text-zinc-200'
+                        }`}
+                      >
+                        {exp.status}
+                      </span>
+                    </td>
+                    <td className="px-6 py-4 text-zinc-700 dark:text-zinc-300">
+                      {exp.sessionIds.length}
+                    </td>
+                    <td className="px-6 py-4 text-zinc-700 dark:text-zinc-300">
+                      {new Date(exp.createdAt).toLocaleString()}
+                    </td>
+                    <td className="px-6 py-4">
+                      {exp.status === 'active' && (
+                        <button
+                          onClick={() => handleStop(exp.id)}
+                          disabled={loading}
+                          className="text-sm font-medium text-red-600 hover:text-red-700 disabled:opacity-50 dark:text-red-400 dark:hover:text-red-300"
+                        >
+                          stop
+                        </button>
+                      )}
+                    </td>
+                  </tr>
+                ))
+              )}
+            </tbody>
+          </table>
+        </div>
+      </div>
+    </div>
+  );
+}

web/src/app/airline/layout.tsx

@@ -0,0 +1,6 @@
+import { ReactNode } from 'react';
+import '@/styles/airline.css';
+
+export default function AirlineLayout({ children }: { children: ReactNode }) {
+  return <div data-mode="airline">{children}</div>;
+}

web/src/app/airline/page.tsx

@@ -0,0 +1,9 @@
+import AirlineHero from '@/components/feats/airline/AirlineHero';
+
+export default function AirlineHome() {
+  return (
+    <main>
+      <AirlineHero />
+    </main>
+  );
+}

web/src/app/airline/products/page.tsx

@@ -0,0 +1,74 @@
+'use client';
+
+import { Navigation } from '@/components/ui';
+import AirlineCard from '@/components/feats/airline/AirlineCard';
+
+type CabinClass = 'economy' | 'premium' | 'business' | 'first';
+type FareRule = 'flexible' | 'standard' | 'basic';
+
+interface Flight {
+  id: string;
+  departure: { time: string; airport: string };
+  arrival: { time: string; airport: string };
+  duration: string;
+  stops: number;
+  cabinClass: CabinClass;
+  fareRule: FareRule;
+  refundable: boolean;
+  basePrice: number;
+}
+
+const genRandomFlights = (): Flight[] => {
+  const airports = ['JFK', 'LAX', 'ORD', 'ATL', 'DFW', 'SFO', 'SEA', 'MIA'];
+  const cabins: CabinClass[] = ['economy', 'premium', 'business', 'first'];
+  const fareRules: FareRule[] = ['flexible', 'standard', 'basic'];
+
+  return Array.from({ length: 12 }, (_, i) => {
+    const depHour = Math.floor(Math.random() * 24);
+    const arrHour = (depHour + Math.floor(Math.random() * 6) + 2) % 24;
+    const stops = Math.random() > 0.6 ? 0 : Math.floor(Math.random() * 2) + 1;
+    const cabin = cabins[Math.floor(Math.random() * cabins.length)];
+    const fareRule = fareRules[Math.floor(Math.random() * fareRules.length)];
+
+    const basePrice = Math.floor(
+      (cabin === 'economy' ? 200 : cabin === 'premium' ? 400 : cabin === 'business' ? 800 : 1500) +
+      Math.random() * 300
+    );
+
+    return {
+      id: `flt-${i}`,
+      departure: {
+        time: `${depHour.toString().padStart(2, '0')}:${Math.floor(Math.random() * 60).toString().padStart(2, '0')}`,
+        airport: airports[Math.floor(Math.random() * airports.length)],
+      },
+      arrival: {
+        time: `${arrHour.toString().padStart(2, '0')}:${Math.floor(Math.random() * 60).toString().padStart(2, '0')}`,
+        airport: airports[Math.floor(Math.random() * airports.length)],
+      },
+      duration: `${Math.floor(Math.random() * 5) + 2}h ${Math.floor(Math.random() * 60)}m`,
+      stops,
+      cabinClass: cabin,
+      fareRule,
+      refundable: Math.random() > 0.7,
+      basePrice,
+    };
+  });
+};
+
+export default function AirlineProducts() {
+  const flights = genRandomFlights();
+
+  return (
+    <>
+      <Navigation />
+      <main className="max-w-7xl mx-auto px-4 py-8">
+        <h1 className="text-3xl font-bold mb-6">Available Flights</h1>
+        <div className="space-y-4">
+          {flights.map((f) => (
+            <AirlineCard key={f.id} flight={f} />
+          ))}
+        </div>
+      </main>
+    </>
+  );
+}

web/src/app/api/admin/experiments/route.ts

@@ -0,0 +1,15 @@
+import { NextResponse } from 'next/server';
+import { getAllExperiments } from '@/lib/sessionStore';
+
+export async function GET() {
+  try {
+    const exps = getAllExperiments();
+    return NextResponse.json({ experiments: exps });
+  } catch (err: any) {
+    console.error('experiments list error:', err);
+    return NextResponse.json(
+      { error: err.message || 'unknown error' },
+      { status: 500 }
+    );
+  }
+}

web/src/app/api/admin/experiments/start/route.ts

@@ -0,0 +1,43 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { randomUUID } from 'crypto';
+import { createExperiment, getSession } from '@/lib/sessionStore';
+
+export async function POST(req: NextRequest) {
+  try {
+    const body = await req.json();
+    const { sessionId } = body;
+
+    if (!sessionId) {
+      return NextResponse.json(
+        { error: 'sessionId required' },
+        { status: 400 }
+      );
+    }
+
+    // verify session exists
+    const session = getSession(sessionId);
+    if (!session) {
+      return NextResponse.json(
+        { error: 'session not found' },
+        { status: 404 }
+      );
+    }
+
+    // generate and create experiment
+    const experimentId = randomUUID();
+    const exp = createExperiment(sessionId, experimentId);
+
+    return NextResponse.json({
+      experimentId: exp.id,
+      sessionId,
+      status: exp.status,
+      createdAt: exp.createdAt,
+    });
+  } catch (err: any) {
+    console.error('experiment start error:', err);
+    return NextResponse.json(
+      { error: err.message || 'unknown error' },
+      { status: 500 }
+    );
+  }
+}

web/src/app/api/admin/experiments/stop/route.ts

@@ -0,0 +1,39 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { stopExperimentById, getExperiment } from '@/lib/sessionStore';
+
+export async function POST(req: NextRequest) {
+  try {
+    const body = await req.json();
+    const { experimentId } = body;
+
+    if (!experimentId) {
+      return NextResponse.json(
+        { error: 'experimentId required' },
+        { status: 400 }
+      );
+    }
+
+    // verify experiment exists
+    const existing = getExperiment(experimentId);
+    if (!existing) {
+      return NextResponse.json(
+        { error: 'experiment not found' },
+        { status: 404 }
+      );
+    }
+
+    // stop the experiment
+    const exp = stopExperimentById(experimentId);
+
+    return NextResponse.json({
+      experimentId: exp!.id,
+      status: exp!.status,
+    });
+  } catch (err: any) {
+    console.error('experiment stop error:', err);
+    return NextResponse.json(
+      { error: err.message || 'unknown error' },
+      { status: 500 }
+    );
+  }
+}

web/src/app/api/ingest/route.ts

@@ -0,0 +1,42 @@
+import { NextRequest, NextResponse } from 'next/server';
+import type { EventBase } from '@/lib/events';
+
+const BACKEND_URL = process.env.BACKEND_URL || 'http://localhost:5000';
+
+export async function POST(req: NextRequest) {
+  try {
+    const body = await req.json();
+
+    const storeMode = process.env.STORE_MODE || 'hotel';
+    const userAgent = req.headers.get('user-agent') || undefined;
+
+    const event: EventBase = {
+      ...body,
+      storeMode,
+      userAgent,
+      ts: body.ts || new Date().toISOString(),
+    };
+
+    const res = await fetch(`${BACKEND_URL}/api/kafka/ingest`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(event),
+    });
+
+    if (!res.ok) {
+      throw new Error(`Backend returned ${res.status}`);
+    }
+
+    if (process.env.NEXT_PUBLIC_APP_ENV === 'dev') {
+      console.log('[ingest]', event);
+    }
+
+    return NextResponse.json({ success: true });
+  } catch (err: any) {
+    console.error('[ingest error]', err);
+    return NextResponse.json(
+      { error: err.message || 'unknown error' },
+      { status: 500 }
+    );
+  }
+}

web/src/app/api/pricing/route.ts

@@ -0,0 +1,45 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+interface PricingResponse {
+    price: number;
+    currency: string;
+    cachedAt: string;
+}
+
+export async function GET(req: NextRequest) {
+    const { searchParams } = new URL(req.url);
+    const productId = searchParams.get('productId');
+    const sessionId = searchParams.get('sessionId');
+    const experimentId = searchParams.get('experimentId');
+    const storeMode = process.env.NEXT_PUBLIC_STORE_MODE || 'shop';
+
+    // log in dev
+    if (process.env.NODE_ENV === 'development') {
+        console.log('[pricing-api]', {
+            productId,
+            sessionId,
+            experimentId,
+            storeMode,
+            timestamp: new Date().toISOString(),
+        });
+    }
+
+    if (!productId) {
+        return NextResponse.json(
+            { error: 'productId is required' },
+            { status: 400 }
+        );
+    }
+
+    // stub: call external pricing provider (random for now)
+    const basePrice = 100 + Math.random() * 900; // 100-1000 range
+    const price = Math.round(basePrice * 100) / 100;
+
+    const response: PricingResponse = {
+        price,
+        currency: 'EUR',
+        cachedAt: new Date().toISOString(),
+    };
+
+    return NextResponse.json(response);
+}

web/src/app/api/session/route.ts

@@ -0,0 +1,46 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { randomUUID } from 'crypto';
+import { getSession, createSession } from '@/lib/sessionStore';
+
+const COOKIE_NAME = 'phantom_session_id';
+const isProd = process.env.NODE_ENV === 'production';
+
+export async function GET(req: NextRequest) {
+    try {
+        // check for existing session cookie
+        const existingSession = req.cookies.get(COOKIE_NAME)?.value;
+
+        if (existingSession) {
+            const sessionData = getSession(existingSession);
+            return NextResponse.json({
+                sessionId: existingSession,
+                experimentId: sessionData?.experimentId,
+            });
+        }
+
+        // mint new session id
+        const sessionId = randomUUID();
+        createSession(sessionId);
+
+        const res = NextResponse.json({ sessionId, experimentId: undefined });
+
+        // set httpOnly cookie with security flags
+        res.cookies.set({
+            name: COOKIE_NAME,
+            value: sessionId,
+            httpOnly: true,
+            sameSite: 'lax',
+            secure: isProd,
+            path: '/',
+            maxAge: 60 * 60 * 24 * 30, // 30 days
+        });
+
+        return res;
+    } catch (err: any) {
+        console.error('session error:', err);
+        return NextResponse.json(
+            { error: err.message || 'unknown error' },
+            { status: 500 }
+        );
+    }
+}

web/src/app/api/track/route.ts

@@ -1,33 +0,0 @@
-import { NextRequest, NextResponse } from 'next/server';
-import { sendInteractionEvent } from '@/lib/kafka';
-
-export async function POST(req: NextRequest) {
-    try {
-        const body = await req.json();
-        const { sessionId, eventType, targetEl, targetUrl, metadata } = body;
-
-        if (!sessionId || !eventType) {
-            return NextResponse.json(
-                { error: 'sessionId and eventType required' },
-                { status: 400 }
-            );
-        }
-
-        await sendInteractionEvent({
-            sessionId,
-            eventType,
-            targetEl,
-            targetUrl,
-            metadata,
-            ts: Date.now(),
-        });
-
-        return NextResponse.json({ success: true });
-    } catch (err: any) {
-        console.error('track error:', err);
-        return NextResponse.json(
-            { error: err.message || 'unknown error' },
-            { status: 500 }
-        );
-    }
-}

web/src/app/globals.css

@@ -1,5 +1,6 @@
 @import "tailwindcss";
 
+@layer base {
 :root {
   --background: #ffffff;
   --foreground: #171717;
@@ -13,6 +14,7 @@
   --border-radius: 8px;
   --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.1);
 }
+}
 
 @theme inline {
   --color-background: var(--background);
@@ -21,6 +23,7 @@
   --font-mono: var(--font-geist-mono);
 }
 
+@layer base {
 @media (prefers-color-scheme: dark) {
   :root {
     --background: #0a0a0a;
@@ -66,7 +69,9 @@ input, select, textarea {
   font-size: 1rem;
   outline: none;
 }
+}
 
+@layer components {
 .container {
   max-width: 1200px;
   margin: 0 auto;
@@ -86,13 +91,19 @@ input, select, textarea {
   font-size: 1rem;
   border-radius: var(--border-radius);
   transition: all 0.2s ease;
+  background-color: #007aff;
+  color: #ffffff;
+  border: none;
+  cursor: pointer;
 }
 
 .btn-primary:hover {
   transform: translateY(-1px);
   box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+  background-color: #0051d5;
 }
 
 .section-spacing {
   margin-bottom: var(--spacing-lg);
 }
+}

web/src/app/hotel/layout.tsx

@@ -0,0 +1,6 @@
+import { ReactNode } from 'react';
+import '@/styles/hotel.css';
+
+export default function HotelLayout({ children }: { children: ReactNode }) {
+  return <div data-mode="hotel">{children}</div>;
+}

web/src/app/hotel/page.tsx

@@ -0,0 +1,9 @@
+import HotelHero from '@/components/feats/hotel/HotelHero';
+
+export default function HotelHome() {
+  return (
+    <main>
+      <HotelHero />
+    </main>
+  );
+}

web/src/app/hotel/products/page.tsx

@@ -0,0 +1,75 @@
+'use client';
+
+import { Navigation } from '@/components/ui';
+import HotelCard from '@/components/feats/hotel/HotelCard';
+
+interface Hotel {
+  id: string;
+  name: string;
+  roomType: string;
+  checkIn: string;
+  checkOut: string;
+  amenities: string[];
+  refundable: boolean;
+  pricePerNight: number;
+  nights: number;
+}
+
+const genRandomHotels = (): Hotel[] => {
+  const names = [
+    'Grand Plaza Hotel',
+    'Seaside Resort',
+    'Downtown Suites',
+    'Mountain View Lodge',
+    'City Center Inn',
+    'Luxury Beach Resort',
+    'Urban Boutique Hotel',
+    'Garden View Hotel',
+  ];
+  const roomTypes = ['Standard Room', 'Deluxe Room', 'Suite', 'Executive Suite', 'Premium Room'];
+  const amenities = ['wifi', 'pool', 'gym', 'parking', 'breakfast', 'spa'];
+
+  return Array.from({ length: 10 }, (_, i) => {
+    const nights = Math.floor(Math.random() * 5) + 1;
+    const basePrice = Math.floor(80 + Math.random() * 220);
+    const selectedAmenities = amenities
+      .sort(() => Math.random() - 0.5)
+      .slice(0, Math.floor(Math.random() * 3) + 2);
+
+    const today = new Date();
+    const checkInDate = new Date(today);
+    checkInDate.setDate(today.getDate() + Math.floor(Math.random() * 10));
+    const checkOutDate = new Date(checkInDate);
+    checkOutDate.setDate(checkInDate.getDate() + nights);
+
+    return {
+      id: `htl-${i}`,
+      name: names[i % names.length],
+      roomType: roomTypes[Math.floor(Math.random() * roomTypes.length)],
+      checkIn: checkInDate.toLocaleDateString('en-US', { month: 'short', day: 'numeric' }),
+      checkOut: checkOutDate.toLocaleDateString('en-US', { month: 'short', day: 'numeric' }),
+      amenities: selectedAmenities,
+      refundable: Math.random() > 0.5,
+      pricePerNight: basePrice,
+      nights,
+    };
+  });
+};
+
+export default function HotelProducts() {
+  const hotels = genRandomHotels();
+
+  return (
+    <>
+      <Navigation />
+      <main className="max-w-7xl mx-auto px-4 py-8">
+        <h1 className="text-3xl font-bold mb-6">Available Hotels</h1>
+        <div className="space-y-4">
+          {hotels.map((h) => (
+            <HotelCard key={h.id} hotel={h} />
+          ))}
+        </div>
+      </main>
+    </>
+  );
+}

web/src/components/feats/airline/AirlineCard.tsx

@@ -0,0 +1,87 @@
+'use client';
+
+import type { EventName } from '@/lib/events';
+import { useHoverTracking } from '@/hooks/useHoverTracking';
+import PriceDisplay from '@/components/ui/PriceDisplay';
+
+const dispatchInteraction = (eventName: EventName, productId?: string, metadata?: Record<string, unknown>) => {
+    const e = new CustomEvent('definedInteraction', {
+        detail: { eventName, productId, metadata },
+    });
+    document.dispatchEvent(e);
+};
+
+type CabinClass = 'economy' | 'premium' | 'business' | 'first';
+type FareRule = 'flexible' | 'standard' | 'basic';
+
+interface Flight {
+    id: string;
+    departure: { time: string; airport: string };
+    arrival: { time: string; airport: string };
+    duration: string;
+    stops: number;
+    cabinClass: CabinClass;
+    fareRule: FareRule;
+    refundable: boolean;
+    basePrice: number;
+}
+
+export default function AirlineCard({ flight }: { flight: Flight }) {
+    const durationRef = useHoverTracking({
+        eventName: 'hover_over_title',
+        productId: flight.id,
+        metadata: { elementText: flight.duration },
+    });
+
+    const priceRef = useHoverTracking({
+        eventName: 'hover_over_paragraph',
+        productId: flight.id,
+        metadata: { elementText: 'price' },
+    });
+
+    const handleCardClick = () => {
+        dispatchInteraction('view_item_page', flight.id, {
+            cabinClass: flight.cabinClass,
+            fareRule: flight.fareRule,
+            price: flight.basePrice,
+        });
+    };
+
+    return (
+        <div
+            className="flight-card cursor-pointer"
+            onClick={handleCardClick}
+        >
+            <div className="flight-timing">
+                <div className="flight-time">{flight.departure.time}</div>
+                <div className="flight-airport">{flight.departure.airport}</div>
+            </div>
+
+            <div className="flight-route">
+                <div ref={durationRef} className="flight-duration">{flight.duration}</div>
+                <div className="flight-stops">
+                    {flight.stops === 0 ? 'Direct' : `${flight.stops} stop${flight.stops > 1 ? 's' : ''}`}
+                </div>
+            </div>
+
+            <div className="flight-timing">
+                <div className="flight-time">{flight.arrival.time}</div>
+                <div className="flight-airport">{flight.arrival.airport}</div>
+            </div>
+
+            <div className="flight-pricing">
+                <div className="fare-class capitalize mb-2">{flight.cabinClass}</div>
+                <div className="text-sm text-[var(--text-secondary)] mb-2 capitalize">{flight.fareRule}</div>
+                {flight.refundable && (
+                    <div className="badge-value text-xs mb-2">Refundable</div>
+                )}
+                <div ref={priceRef}>
+                    <PriceDisplay
+                        productId={flight.id}
+                        className="fare-price"
+                    />
+                </div>
+            </div>
+        </div>
+    );
+}

web/src/components/feats/airline/AirlineHero.tsx

@@ -0,0 +1,156 @@
+'use client';
+
+import { useState, FormEvent } from 'react';
+import { Button, Label, Input, DateInput, RadioGroup, Dropdown, DropdownCounter } from '@/components/ui';
+
+type TripType = 'roundtrip' | 'oneway' | 'multicity';
+
+const PlaneIcon = () => (
+  <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 19l9 2-9-18-9 18 9-2zm0 0v-8" />
+  </svg>
+);
+
+const LocationIcon = () => (
+  <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17.657 16.657L13.414 20.9a1.998 1.998 0 01-2.827 0l-4.244-4.243a8 8 0 1111.314 0z" />
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 11a3 3 0 11-6 0 3 3 0 016 0z" />
+  </svg>
+);
+
+export default function AirlineHero() {
+  const [tripType, setTripType] = useState<TripType>('roundtrip');
+  const [origin, setOrigin] = useState('');
+  const [destination, setDestination] = useState('');
+  const [departDate, setDepartDate] = useState('');
+  const [returnDate, setReturnDate] = useState('');
+  const [passengers, setPassengers] = useState({ adults: 1, children: 0, infants: 0 });
+
+  const handleSearch = (e: FormEvent) => {
+    e.preventDefault();
+    console.log({ tripType, origin, destination, departDate, returnDate, passengers });
+  };
+
+  const totalPax = passengers.adults + passengers.children + passengers.infants;
+
+  return (
+    <div className="hero-section min-h-[70vh] flex items-center justify-center">
+      <div className="w-full max-w-5xl px-4">
+        <div className="text-center mb-8">
+          <h1 className="text-4xl md:text-5xl font-bold mb-4">
+            Book flights at the best prices
+          </h1>
+          <p className="text-lg">
+            Compare hundreds of airlines and find the perfect flight for your journey
+          </p>
+        </div>
+
+        <div className="search-form">
+          <form onSubmit={handleSearch}>
+            <div className="mb-6">
+              <RadioGroup
+                name="tripType"
+                value={tripType}
+                onChange={setTripType}
+                options={[
+                  { value: 'roundtrip', label: 'Round-trip' },
+                  { value: 'oneway', label: 'One-way' },
+                  { value: 'multicity', label: 'Multi-city' },
+                ]}
+              />
+            </div>
+
+            <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
+              <div>
+                <Label htmlFor="origin">From</Label>
+                <Input
+                  type="text"
+                  id="origin"
+                  value={origin}
+                  onChange={(e) => setOrigin(e.target.value)}
+                  placeholder="Airport or city"
+                  icon={<PlaneIcon />}
+                  required
+                />
+              </div>
+
+              <div>
+                <Label htmlFor="destination">To</Label>
+                <Input
+                  type="text"
+                  id="destination"
+                  value={destination}
+                  onChange={(e) => setDestination(e.target.value)}
+                  placeholder="Airport or city"
+                  icon={<LocationIcon />}
+                  required
+                />
+              </div>
+
+              <div>
+                <Label htmlFor="departDate">Departure</Label>
+                <DateInput
+                  id="departDate"
+                  value={departDate}
+                  onChange={(e) => setDepartDate(e.target.value)}
+                  required
+                />
+              </div>
+
+              <div>
+                <Label htmlFor="returnDate">Return</Label>
+                {tripType === 'roundtrip' ? (
+                  <DateInput
+                    id="returnDate"
+                    value={returnDate}
+                    onChange={(e) => setReturnDate(e.target.value)}
+                    required
+                  />
+                ) : (
+                  <DateInput id="returnDate" disabled />
+                )}
+              </div>
+            </div>
+
+            <div className="grid grid-cols-4 sm:grid-cols-3 lg:grid-cols-4 gap-4 mt-4">
+              <div className="sm:col-span-1 lg:col-span-1">
+                <Label htmlFor="passengers">Passengers</Label>
+                <Dropdown label={`${totalPax} ${totalPax === 1 ? 'passenger' : 'passengers'}`}>
+                  <DropdownCounter
+                    label="Adults"
+                    sublabel="12+ years"
+                    value={passengers.adults}
+                    min={1}
+                    onChange={(v) => setPassengers({ ...passengers, adults: v })}
+                  />
+                  <DropdownCounter
+                    label="Children"
+                    sublabel="2-11 years"
+                    value={passengers.children}
+                    onChange={(v) => setPassengers({ ...passengers, children: v })}
+                  />
+                  <DropdownCounter
+                    label="Infants"
+                    sublabel="Under 2"
+                    value={passengers.infants}
+                    onChange={(v) => setPassengers({ ...passengers, infants: v })}
+                  />
+                </Dropdown>
+              </div>
+            </div>
+
+            <div className="mt-6">
+              <Button type="submit" fullWidth>
+                Search Flights
+              </Button>
+            </div>
+          </form>
+        </div>
+
+        <div className="mt-6 text-center text-sm">
+          <p>Direct flights available · Flexible booking · Compare 500+ airlines worldwide</p>
+        </div>
+      </div>
+    </div>
+  );
+}

web/src/components/feats/hotel/HotelCard.tsx

@@ -0,0 +1,98 @@
+'use client';
+
+import type { EventName } from '@/lib/events';
+import { useHoverTracking } from '@/hooks/useHoverTracking';
+import PriceDisplay from '@/components/ui/PriceDisplay';
+
+const dispatchInteraction = (eventName: EventName, productId?: string, metadata?: Record<string, unknown>) => {
+    const e = new CustomEvent('definedInteraction', {
+        detail: { eventName, productId, metadata },
+    });
+    document.dispatchEvent(e);
+};
+
+interface Hotel {
+    id: string;
+    name: string;
+    roomType: string;
+    checkIn: string;
+    checkOut: string;
+    amenities: string[];
+    refundable: boolean;
+    pricePerNight: number;
+    nights: number;
+}
+
+const AmenityIcon = ({ name }: { name: string }) => {
+    const iconMap: Record<string, string> = {
+        wifi: 'Wi-Fi',
+        pool: 'Pool',
+        gym: 'Gym',
+        parking: 'Parking',
+        breakfast: 'Breakfast',
+        spa: 'Spa',
+    };
+    return <span className="feature-tag">{iconMap[name.toLowerCase()] || name}</span>;
+};
+
+export default function HotelCard({ hotel }: { hotel: Hotel }) {
+    const titleRef = useHoverTracking({
+        eventName: 'hover_over_title',
+        productId: hotel.id,
+        metadata: { elementText: hotel.name },
+    });
+
+    const priceRef = useHoverTracking({
+        eventName: 'hover_over_paragraph',
+        productId: hotel.id,
+        metadata: { elementText: 'price' },
+    });
+
+    const handleCardClick = () => {
+        dispatchInteraction('view_item_page', hotel.id, {
+            roomType: hotel.roomType,
+            price: hotel.pricePerNight,
+            nights: hotel.nights,
+        });
+    };
+
+    return (
+        <div
+            className="hotel-card cursor-pointer"
+            onClick={handleCardClick}
+        >
+            <div className="hotel-image bg-gray-200 flex items-center justify-center">
+                <span className="text-gray-400 text-sm">Image</span>
+            </div>
+
+            <div className="hotel-info">
+                <h3 ref={titleRef} className="hotel-name">{hotel.name}</h3>
+                <div className="hotel-location text-sm mb-2">{hotel.roomType}</div>
+                <div className="text-sm text-[var(--text-secondary)] mb-2">
+                    {hotel.checkIn} - {hotel.checkOut}
+                </div>
+                <div className="hotel-features">
+                    {hotel.amenities.map((a) => (
+                        <AmenityIcon key={a} name={a} />
+                    ))}
+                </div>
+                {hotel.refundable && (
+                    <div className="free-cancellation mt-2">Free cancellation</div>
+                )}
+            </div>
+
+            <div className="hotel-pricing">
+                <div ref={priceRef}>
+                    <PriceDisplay
+                        productId={hotel.id}
+                        className="price-wrapper"
+                        perNight
+                    />
+                </div>
+                <div className="text-xs text-[var(--text-secondary)] mt-1">
+                    Total for {hotel.nights} night{hotel.nights > 1 ? 's' : ''}
+                </div>
+            </div>
+        </div>
+    );
+}

web/src/components/feats/hotel/HotelHero.tsx

@@ -0,0 +1,103 @@
+'use client';
+
+import { useState, FormEvent } from 'react';
+import { Button, Label, Input, DateInput, Dropdown, DropdownCounter } from '@/components/ui';
+
+const LocationIcon = () => (
+  <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17.657 16.657L13.414 20.9a1.998 1.998 0 01-2.827 0l-4.244-4.243a8 8 0 1111.314 0z" />
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 11a3 3 0 11-6 0 3 3 0 016 0z" />
+  </svg>
+);
+
+export default function HotelHero() {
+  const [destination, setDestination] = useState('');
+  const [checkIn, setCheckIn] = useState('');
+  const [checkOut, setCheckOut] = useState('');
+  const [guests, setGuests] = useState({ adults: 2, rooms: 1 });
+
+  const handleSearch = (e: FormEvent) => {
+    e.preventDefault();
+    console.log({ destination, checkIn, checkOut, guests });
+  };
+
+  return (
+    <div className="hero-section min-h-[70vh] flex items-center justify-center">
+      <div className="w-full max-w-4xl px-4">
+        <div className="text-center mb-8">
+          <h1 className="text-4xl md:text-5xl font-bold mb-4">
+            Find your perfect stay
+          </h1>
+          <p className="text-lg">
+            Search hotels, compare prices, and book with confidence
+          </p>
+        </div>
+
+        <form onSubmit={handleSearch} className="search-form">
+          <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
+            <div className="sm:col-span-2">
+              <Label htmlFor="destination">Where to?</Label>
+              <Input
+                type="text"
+                id="destination"
+                value={destination}
+                onChange={(e) => setDestination(e.target.value)}
+                placeholder="City, hotel, or landmark"
+                icon={<LocationIcon />}
+                required
+              />
+            </div>
+
+            <div>
+              <Label htmlFor="checkIn">Check-in</Label>
+              <DateInput
+                id="checkIn"
+                value={checkIn}
+                onChange={(e) => setCheckIn(e.target.value)}
+                required
+              />
+            </div>
+
+            <div>
+              <Label htmlFor="checkOut">Check-out</Label>
+              <DateInput
+                id="checkOut"
+                value={checkOut}
+                onChange={(e) => setCheckOut(e.target.value)}
+                required
+              />
+            </div>
+
+            <div className="sm:col-span-2 lg:col-span-4">
+              <Label htmlFor="guests">Guests & Rooms</Label>
+              <Dropdown label={`${guests.adults} ${guests.adults === 1 ? 'adult' : 'adults'}, ${guests.rooms} ${guests.rooms === 1 ? 'room' : 'rooms'}`}>
+                <DropdownCounter
+                  label="Adults"
+                  value={guests.adults}
+                  min={1}
+                  onChange={(v) => setGuests({ ...guests, adults: v })}
+                />
+                <DropdownCounter
+                  label="Rooms"
+                  value={guests.rooms}
+                  min={1}
+                  onChange={(v) => setGuests({ ...guests, rooms: v })}
+                />
+              </Dropdown>
+            </div>
+
+            <div className="sm:col-span-2 lg:col-span-4">
+              <Button type="submit" fullWidth>
+                Search Hotels
+              </Button>
+            </div>
+          </div>
+        </form>
+
+        <div className="mt-6 text-center text-sm">
+          <p>Over 2 million hotels worldwide · Best price guarantee · Free cancellation on most bookings</p>
+        </div>
+      </div>
+    </div>
+  );
+}

web/src/components/ui/Button.tsx

@@ -0,0 +1,20 @@
+import { ReactNode, ButtonHTMLAttributes } from 'react';
+
+type BtnVariant = 'primary' | 'secondary';
+
+interface BtnProps extends ButtonHTMLAttributes<HTMLButtonElement> {
+  variant?: BtnVariant;
+  children: ReactNode;
+  fullWidth?: boolean;
+}
+
+export default function Button({ variant = 'primary', children, fullWidth, className = '', ...props }: BtnProps) {
+  const baseClass = variant === 'primary' ? 'btn-primary' : 'btn-secondary';
+  const widthClass = fullWidth ? 'w-full' : '';
+
+  return (
+    <button className={`${baseClass} ${widthClass} ${className}`.trim()} {...props}>
+      {children}
+    </button>
+  );
+}

web/src/components/ui/DateInput.tsx

@@ -0,0 +1,7 @@
+import { InputHTMLAttributes } from 'react';
+
+interface DateInpProps extends Omit<InputHTMLAttributes<HTMLInputElement>, 'type'> {}
+
+export default function DateInput({ className = '', ...props }: DateInpProps) {
+  return <input type="date" className={`input-field ${className}`.trim()} {...props} />;
+}

web/src/components/ui/Dropdown.tsx

@@ -0,0 +1,83 @@
+'use client';
+
+import { ReactNode, useState, useRef, useEffect } from 'react';
+
+interface DropdownProps {
+  label: string;
+  children: ReactNode;
+}
+
+export default function Dropdown({ label, children }: DropdownProps) {
+  const [open, setOpen] = useState(false);
+  const ref = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const handleClick = (e: MouseEvent) => {
+      if (ref.current && !ref.current.contains(e.target as Node)) {
+        setOpen(false);
+      }
+    };
+
+    document.addEventListener('mousedown', handleClick);
+    return () => document.removeEventListener('mousedown', handleClick);
+  }, []);
+
+  return (
+    <div className="relative" ref={ref}>
+      <button
+        type="button"
+        onClick={() => setOpen(!open)}
+        className="input-field flex justify-between items-center w-full"
+      >
+        <span>{label}</span>
+        <svg className="w-5 h-5 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 9l-7 7-7-7" />
+        </svg>
+      </button>
+      {open && (
+        <div className="absolute z-10 mt-2 w-full bg-white border border-gray-200 rounded-lg shadow-lg p-4">
+          {children}
+        </div>
+      )}
+    </div>
+  );
+}
+
+interface CounterProps {
+  label: string;
+  sublabel?: string;
+  value: number;
+  min?: number;
+  max?: number;
+  onChange: (val: number) => void;
+}
+
+export function DropdownCounter({ label, sublabel, value, min = 0, max = 99, onChange }: CounterProps) {
+  return (
+    <div className="flex justify-between items-center py-3 border-b border-gray-100 last:border-b-0">
+      <div className="flex flex-col">
+        <span className="text-sm font-medium text-gray-900">{label}</span>
+        {sublabel && <span className="text-xs text-gray-500 mt-0.5">{sublabel}</span>}
+      </div>
+      <div className="flex items-center gap-3">
+        <button
+          type="button"
+          onClick={() => onChange(Math.max(min, value - 1))}
+          disabled={value <= min}
+          className="w-9 h-9 rounded-full border-2 border-gray-300 flex items-center justify-center hover:border-blue-500 hover:bg-blue-50 disabled:opacity-40 disabled:cursor-not-allowed disabled:hover:border-gray-300 disabled:hover:bg-transparent transition-colors text-lg font-medium text-gray-700"
+        >
+          −
+        </button>
+        <span className="w-10 text-center font-semibold text-gray-900">{value}</span>
+        <button
+          type="button"
+          onClick={() => onChange(Math.min(max, value + 1))}
+          disabled={value >= max}
+          className="w-9 h-9 rounded-full border-2 border-gray-300 flex items-center justify-center hover:border-blue-500 hover:bg-blue-50 disabled:opacity-40 disabled:cursor-not-allowed disabled:hover:border-gray-300 disabled:hover:bg-transparent transition-colors text-lg font-medium text-gray-700"
+        >
+          +
+        </button>
+      </div>
+    </div>
+  );
+}

web/src/components/ui/Input.tsx

@@ -0,0 +1,29 @@
+import { InputHTMLAttributes, ReactNode } from 'react';
+
+interface InpProps extends InputHTMLAttributes<HTMLInputElement> {
+    icon?: ReactNode;
+}
+
+export default function Input({ icon, className = '', style, ...props }: InpProps) {
+    const padClass = icon ? 'pl-10' : '';
+    // Fallback if a custom CSS rule still overrides Tailwind
+    const mergedStyle = icon ? { paddingInlineStart: '2.5rem', ...style } : style;
+
+    return (
+        <div className="relative">
+            {icon && (
+                <div
+                    aria-hidden
+                    className="pointer-events-none absolute inset-y-0 left-0 flex items-center pl-3 text-gray-400 z-10"
+                >
+                    {icon}
+                </div>
+            )}
+            <input
+                className={`input-field ${className} ${padClass}`}
+                style={mergedStyle}
+                {...props}
+            />
+        </div>
+    );
+}

web/src/components/ui/Label.tsx

@@ -0,0 +1,13 @@
+import { ReactNode, LabelHTMLAttributes } from 'react';
+
+interface LblProps extends LabelHTMLAttributes<HTMLLabelElement> {
+  children: ReactNode;
+}
+
+export default function Label({ children, className = '', ...props }: LblProps) {
+  return (
+    <label className={`block text-sm font-medium mb-2 ${className}`.trim()} {...props}>
+      {children}
+    </label>
+  );
+}

web/src/components/ui/Navigation.tsx

@@ -0,0 +1,48 @@
+'use client';
+
+import Link from 'next/link';
+import { usePathname } from 'next/navigation';
+import type { EventName } from '@/lib/events';
+
+const dispatchInteraction = (eventName: EventName, metadata?: Record<string, unknown>) => {
+  const e = new CustomEvent('definedInteraction', {
+    detail: { eventName, metadata },
+  });
+  document.dispatchEvent(e);
+};
+
+const NavLink = ({ href, children }: { href: string; children: React.ReactNode }) => {
+  const path = usePathname();
+  const isActive = path === href;
+
+  return (
+    <Link
+      href={href}
+      className={`px-4 py-2 rounded-md transition-colors ${
+        isActive
+          ? 'bg-[var(--accent-primary)] text-white font-semibold'
+          : 'hover:bg-[var(--accent-primary-light)] text-[var(--text-primary)]'
+      }`}
+    >
+      {children}
+    </Link>
+  );
+};
+
+export default function Navigation() {
+  return (
+    <nav className="bg-[var(--bg-primary)] border-b border-gray-200 shadow-sm">
+      <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8">
+        <div className="flex justify-between h-16">
+          <div className="flex items-center space-x-1">
+            <NavLink href="/">Home</NavLink>
+            <NavLink href="/products">Products</NavLink>
+            <NavLink href="/search">Search</NavLink>
+            <NavLink href="/cart">Cart</NavLink>
+            <NavLink href="/checkout">Checkout</NavLink>
+          </div>
+        </div>
+      </div>
+    </nav>
+  );
+}

web/src/components/ui/PriceDisplay.tsx

@@ -0,0 +1,136 @@
+'use client';
+
+import { useEffect, useState, useRef } from 'react';
+
+interface PriceDisplayProps {
+    productId: string;
+    className?: string;
+    perNight?: boolean;
+}
+
+interface PricingData {
+    price: number;
+    currency: string;
+    cachedAt: string;
+}
+
+interface SessionData {
+    sessionId: string;
+    experimentId?: string;
+}
+
+const fetchSession = async (): Promise<SessionData> => {
+    try {
+        const res = await fetch('/api/session');
+        const data = await res.json();
+        return {
+            sessionId: data.sessionId || '',
+            experimentId: data.experimentId || '',
+        };
+    } catch (err) {
+        console.error('failed to fetch session:', err);
+        return { sessionId: '', experimentId: '' };
+    }
+};
+
+const formatPrice = (price: number, currency: string) => {
+    return new Intl.NumberFormat('en-US', { // like an std localization
+        style: 'currency',
+        currency,
+    }).format(price);
+};
+
+const isCacheStale = (cachedAt: string, thresholdMs = 60000) => {
+    const cacheTime = new Date(cachedAt).getTime();
+    const now = Date.now();
+    return now - cacheTime > thresholdMs;
+};
+
+export default function PriceDisplay({
+    productId,
+    className = '',
+    perNight = false,
+}: PriceDisplayProps) {
+    const sessionRef = useRef<SessionData | null>(null);
+    const [data, setData] = useState<PricingData | null>(null);
+    const [loading, setLoading] = useState(true);
+    const [error, setError] = useState<string | null>(null);
+
+    useEffect(() => {
+        const initAndFetch = async () => {
+            setLoading(true);
+            setError(null);
+
+            try {
+                // fetch session if not already loaded
+                if (!sessionRef.current) {
+                    sessionRef.current = await fetchSession();
+                }
+
+                const { sessionId, experimentId } = sessionRef.current;
+
+                if (!sessionId) {
+                    setError('Invalid session');
+                    setLoading(false);
+                    return;
+                }
+
+                const params = new URLSearchParams({
+                    productId,
+                    sessionId,
+                    experimentId: experimentId || '',
+                });
+
+                const res = await fetch(`/api/pricing?${params.toString()}`);
+
+                if (!res.ok) {
+                    throw new Error(`Failed to fetch price: ${res.status}`);
+                }
+
+                const pricingData: PricingData = await res.json();
+                setData(pricingData);
+            } catch (err) {
+                setError(err instanceof Error ? err.message : 'Unknown error');
+            } finally {
+                setLoading(false);
+            }
+        };
+
+        initAndFetch();
+    }, [productId]);
+
+    if (loading) {
+        return (
+            <div className={`price-loading ${className}`}>
+                <div className="spinner-border animate-spin inline-block w-4 h-4 border-2 rounded-full" role="status">
+                    <span className="sr-only">Loading...</span>
+                </div>
+            </div>
+        );
+    }
+
+    if (error || !data) {
+        return (
+            <div className={`price-error ${className}`}>
+                <span className="text-red-500 text-sm">Price unavailable</span>
+            </div>
+        );
+    }
+
+    const isStale = isCacheStale(data.cachedAt);
+    const formattedPrice = formatPrice(data.price, data.currency);
+
+    return (
+        <div className={`price-display ${className}`}>
+            <div className="price-amount">
+                {formattedPrice}
+                {perNight && <span className="text-xs ml-1">/night</span>}
+            </div>
+            {isStale && (
+                <span className="price-stale text-xs text-yellow-600" title={`Cached at ${data.cachedAt}`}>
+                    prices may be outdated
+                </span>
+            )}
+        </div>
+    );
+}

web/src/components/ui/RadioGroup.tsx

@@ -0,0 +1,33 @@
+'use client';
+
+interface RadioOpt<T extends string> {
+  value: T;
+  label: string;
+}
+
+interface RadioGrpProps<T extends string> {
+  name: string;
+  options: RadioOpt<T>[];
+  value: T;
+  onChange: (val: T) => void;
+}
+
+export default function RadioGroup<T extends string>({ name, options, value, onChange }: RadioGrpProps<T>) {
+  return (
+    <div className="flex gap-4">
+      {options.map((opt) => (
+        <label key={opt.value} className="flex items-center cursor-pointer">
+          <input
+            type="radio"
+            name={name}
+            value={opt.value}
+            checked={value === opt.value}
+            onChange={(e) => onChange(e.target.value as T)}
+            className="mr-2"
+          />
+          <span className="text-sm">{opt.label}</span>
+        </label>
+      ))}
+    </div>
+  );
+}

web/src/components/ui/index.ts

@@ -0,0 +1,7 @@
+export { default as Button } from './Button';
+export { default as Label } from './Label';
+export { default as Input } from './Input';
+export { default as DateInput } from './DateInput';
+export { default as RadioGroup } from './RadioGroup';
+export { default as Dropdown, DropdownCounter } from './Dropdown';
+export { default as Navigation } from './Navigation';

web/src/hooks/useHoverTracking.ts

@@ -0,0 +1,63 @@
+import { useCallback, useRef } from 'react';
+import type { EventName } from '@/lib/events';
+
+const dispatchInteraction = (
+    eventName: EventName,
+    productId?: string,
+    metadata?: Record<string, unknown>
+) => {
+    const e = new CustomEvent('definedInteraction', {
+        detail: { eventName, productId, metadata },
+    });
+    document.dispatchEvent(e);
+};
+
+interface UseHoverTrackingOptions {
+    eventName: EventName;
+    productId?: string;
+    metadata?: Record<string, unknown>;
+    threshold?: number; // ms, default 1500 or NEXT_PUBLIC_HOVER_THRESHOLD
+}
+
+export const useHoverTracking = (options: UseHoverTrackingOptions) => {
+    const defaultThreshold = process.env.NEXT_PUBLIC_HOVER_THRESHOLD
+        ? parseInt(process.env.NEXT_PUBLIC_HOVER_THRESHOLD, 10)
+        : 1500;
+    const { eventName, productId, metadata, threshold = defaultThreshold } = options;
+    const timerRef = useRef<NodeJS.Timeout | undefined>(undefined);
+    const startRef = useRef<number | undefined>(undefined);
+
+    return useCallback((node: HTMLElement | null) => {
+        if (!node) {
+            if (timerRef.current) clearTimeout(timerRef.current);
+            return;
+        }
+
+        const onEnter = () => {
+            startRef.current = Date.now();
+            timerRef.current = setTimeout(() => {
+                const dwellTime = Date.now() - startRef.current!;
+                dispatchInteraction(eventName, productId, {
+                    ...metadata,
+                    dwellTime,
+                });
+            }, threshold);
+        };
+
+        const onLeave = () => {
+            if (timerRef.current) {
+                clearTimeout(timerRef.current);
+                timerRef.current = undefined;
+            }
+        };
+
+        node.addEventListener('mouseenter', onEnter);
+        node.addEventListener('mouseleave', onLeave);
+
+        return () => {
+            node.removeEventListener('mouseenter', onEnter);
+            node.removeEventListener('mouseleave', onLeave);
+            if (timerRef.current) clearTimeout(timerRef.current);
+        };
+    }, [eventName, productId, metadata, threshold]);
+};

web/src/hooks/useInteractionTracking.ts

@@ -1,117 +1,86 @@
-import { useEffect, useRef } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import '@/lib/experiments' // ensure experiments lib is loaded
+import type { EventName } from '@/lib/events';
 
-const genSessionId = () => {
-    if (typeof window === 'undefined') return '';
-    let sid = sessionStorage.getItem('phantom_session_id');
-    if (!sid) {
-        sid = `${Date.now()}-${Math.random().toString(36).slice(2)}`;
-        sessionStorage.setItem('phantom_session_id', sid);
-        // TODO: when creating new id send to exepriemtn tracking db
-        // match between sesion-id and experiment-id for this session
-        // so that we can identify all interactions aligning with a specific experiment goal.
-    }
-    return sid;
+const fetchSessionId = async (): Promise<string> => {
+  try {
+    const res = await fetch('/api/session');
+    const data = await res.json();
+    return data.sessionId || '';
+  } catch (err) {
+    console.error('failed to fetch session:', err);
+    return '';
+  }
 };
 
 const track = async (ev: {
-    sessionId: string;
-    eventType: string;
-    targetEl?: string;
-    targetUrl?: string;
-    metadata?: Record<string, any>;
+  sessionId: string;
+  eventName: EventName;
+  page: string;
+  productId?: string;
+  metadata?: Record<string, unknown>;
 }) => {
-    try {
-        await fetch('/api/track', {
-            method: 'POST',
-            headers: { 'Content-Type': 'application/json' },
-            body: JSON.stringify(ev),
-        });
-    } catch (err) {
-        console.error('track failed:', err);
-    }
+  try {
+    await fetch('/api/ingest', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(ev),
+    });
+  } catch (err) {
+    console.error('track failed:', err);
+  }
 };
 
 export const useInteractionTracking = () => {
     const sidRef = useRef<string>('');
+    const [ready, setReady] = useState(false);
 
     useEffect(() => {
-        sidRef.current = genSessionId();
-
-        const handleClick = (e: MouseEvent) => {
-            const tgt = e.target as HTMLElement;
-            track({
-                sessionId: sidRef.current,
-                eventType: 'click',
-                targetEl: tgt.tagName,
-                targetUrl: tgt instanceof HTMLAnchorElement ? tgt.href : undefined,
-                metadata: {
-                    x: e.clientX,
-                    y: e.clientY,
-                    path: window.location.pathname,
-                },
-            });
-        };
-
-        const handleScroll = () => {
-            track({
-                sessionId: sidRef.current,
-                eventType: 'scroll',
-                metadata: {
-                    scrollY: window.scrollY,
-                    path: window.location.pathname,
-                },
-            });
-        };
+        // fetch session id from httpOnly cookie via API
+        fetchSessionId().then((sid) => {
+            sidRef.current = sid;
+            setReady(true);
+        });
 
         const handlePageView = () => {
+            if (!sidRef.current) return;
+            const page = window.location.pathname;
             track({
                 sessionId: sidRef.current,
-                eventType: 'pageview',
+                eventName: 'page_view',
+                page,
                 metadata: {
-                    path: window.location.pathname,
                     referrer: document.referrer,
                 },
             });
         };
 
-        enum DefinedInteractions {
-            ADD_TO_CART = 'add_to_cart',
-            PURCHASE = 'purchase',
-        }
-
-        // called when clicking on "Add to Cart" button or "Purchase" button
-        const handleDefinedInteraction = (
-            interactionType: DefinedInteractions,
-            metadata?: Record<string, any>
-        ) => {
+        // called for canonical events dispatched via custom events
+        const handleDefinedInteraction = (e: Event) => {
+            if (!sidRef.current) return;
+            const customEvent = e as CustomEvent<{
+                eventName: EventName;
+                productId?: string;
+                metadata?: Record<string, unknown>;
+            }>;
+            const page = window.location.pathname;
             track({
                 sessionId: sidRef.current,
-                eventType: interactionType,
-                metadata: {
-                    path: window.location.pathname,
-                    ...metadata,
-                },
+                eventName: customEvent.detail.eventName,
+                page,
+                productId: customEvent.detail.productId,
+                metadata: customEvent.detail.metadata,
             });
         };
 
+        // wait for session to be ready before tracking
+        if (!ready) return;
 
         handlePageView();
-        document.addEventListener('click', handleClick);
-        document.addEventListener('definedInteraction', (e: Event) => {
-            const customEvent = e as CustomEvent;
-            handleDefinedInteraction(customEvent.detail.interactionType, customEvent.detail.metadata);
-        });
-        // TOO NOISY: enable if needed but tbh not worth it
-        //window.addEventListener('scroll', handleScroll, { passive: true });
+        document.addEventListener('definedInteraction', handleDefinedInteraction);
 
         return () => {
-            document.removeEventListener('click', handleClick);
-            document.removeEventListener('definedInteraction', (e: Event) => {
-                const customEvent = e as CustomEvent;
-                handleDefinedInteraction(customEvent.detail.interactionType, customEvent.detail.metadata);
-            });
-            //window.removeEventListener('scroll', handleScroll);
+            document.removeEventListener('definedInteraction', handleDefinedInteraction);
         };
-    }, []);
+    }, [ready]);
 };

web/src/hooks/useSession.ts

@@ -0,0 +1,38 @@
+import { useEffect, useState } from 'react';
+
+type SessionState = {
+  sessionId: string | null;
+  experimentId: string | null;
+  isLoading: boolean;
+};
+
+export const useSession = () => {
+  const [state, setState] = useState<SessionState>({
+    sessionId: null,
+    experimentId: null,
+    isLoading: true,
+  });
+
+  useEffect(() => {
+    const fetchSession = async () => {
+      try {
+        const res = await fetch('/api/session');
+        if (!res.ok) throw new Error(`fetch failed: ${res.status}`);
+
+        const data = await res.json();
+        setState({
+          sessionId: data.sessionId || null,
+          experimentId: data.experimentId || null,
+          isLoading: false,
+        });
+      } catch (err) {
+        console.error('session fetch error:', err);
+        setState({ sessionId: null, experimentId: null, isLoading: false });
+      }
+    };
+
+    fetchSession();
+  }, []);
+
+  return state;
+};

web/src/lib/config.ts

@@ -0,0 +1,30 @@
+import { z } from 'zod';
+
+type Env = z.infer<typeof envSchema>;
+const envSchema = z.object({
+    STORE_MODE: z.enum(['hotel', 'airline'], {
+        message: 'STORE_MODE must be either "hotel" or "airline"'
+    }),
+    NEXT_PUBLIC_API_BASE: z.string().url({
+        message: 'NEXT_PUBLIC_API_BASE must be a valid URL (e.g., http://localhost:3000)'
+    }),
+    NEXT_PUBLIC_APP_ENV: z.enum(['dev', 'prod'], {
+        message: 'NEXT_PUBLIC_APP_ENV must be either "dev" or "prod"'
+    }),
+});
+
+// parse and validate env at module load, fail fast with descriptive errors
+const parseEnv = (): Env => {
+    const result = envSchema.safeParse({
+        STORE_MODE: process.env.STORE_MODE,
+        NEXT_PUBLIC_API_BASE: process.env.NEXT_PUBLIC_API_BASE,
+        NEXT_PUBLIC_APP_ENV: process.env.NEXT_PUBLIC_APP_ENV,
+    });
+    if (!result.success) {
+        const errors = result.error.issues.map((err) => `${err.path.join('.')}: ${err.message}`).join('\n');
+        throw new Error(`Environment validation failed:\n${errors}`);
+    }
+    return result.data;
+};
+
+export const config: Env = parseEnv();

web/src/lib/events.ts

@@ -0,0 +1,91 @@
+import { z } from 'zod';
+
+// canonical events for tracking user interactions
+export type EventName =
+  // navigation & discovery
+  | 'page_view'
+  | 'view_item_page'
+  | 'learn_more_about_item'
+  // cart operations
+  | 'add_item_to_cart'
+  | 'remove_item'
+  | 'checkout_start'
+  | 'purchase_complete'
+  // filtering & search
+  | 'search'
+  | 'filter_for_date'
+  | 'filter_for_amenities'
+  | 'filter_for_price'
+  | 'sort_change'
+  // dwell signals (Ns threshold)
+  | 'hover_over_title'
+  | 'hover_over_paragraph'
+  | 'hover_over_link'
+  | 'hover_over_button'
+  // session
+  | 'session_start';
+
+export const eventNames: readonly EventName[] = [
+  'page_view',
+  'view_item_page',
+  'learn_more_about_item',
+  'add_item_to_cart',
+  'remove_item',
+  'checkout_start',
+  'purchase_complete',
+  'search',
+  'filter_for_date',
+  'filter_for_amenities',
+  'filter_for_price',
+  'sort_change',
+  'hover_over_title',
+  'hover_over_paragraph',
+  'hover_over_link',
+  'hover_over_button',
+  'session_start',
+] as const;
+
+export interface EventBase {
+  sessionId: string;
+  experimentId?: string;
+  storeMode: 'hotel' | 'airline';
+  ts: string; // ISO8601
+  page: string;
+  eventName: EventName;
+  productId?: string;
+  metadata?: Record<string, unknown>;
+  userAgent?: string;
+}
+
+// zod schema for runtime validation
+export const eventBaseSchema = z.object({
+  sessionId: z.string().min(1),
+  experimentId: z.string().optional(),
+  storeMode: z.enum(['hotel', 'airline']),
+  ts: z.string().datetime(), // validates ISO8601
+  page: z.string().min(1),
+  eventName: z.enum([
+    'page_view',
+    'view_item_page',
+    'learn_more_about_item',
+    'add_item_to_cart',
+    'remove_item',
+    'checkout_start',
+    'purchase_complete',
+    'search',
+    'filter_for_date',
+    'filter_for_amenities',
+    'filter_for_price',
+    'sort_change',
+    'hover_over_title',
+    'hover_over_paragraph',
+    'hover_over_link',
+    'hover_over_button',
+    'session_start',
+  ]),
+  productId: z.string().optional(),
+  metadata: z.record(z.string(), z.unknown()).optional(),
+  userAgent: z.string().optional(),
+});
+
+export type EventBaseValidated = z.infer<typeof eventBaseSchema>;

web/src/lib/kafka.ts

@@ -1,42 +0,0 @@
-import { Kafka, Producer } from 'kafkajs';
-
-let producer: Producer | null = null;
-
-const kafka = new Kafka({
-    clientId: 'phantom-web',
-    brokers: [`${process.env.KAFKA_HOST || 'localhost'}:${process.env.KAFKA_PORT || '9092'}`],
-});
-
-export const getProducer = async (): Promise<Producer> => {
-    if (!producer) {
-        producer = kafka.producer();
-        await producer.connect();
-    }
-    return producer;
-};
-
-export const sendInteractionEvent = async (ev: {
-    sessionId: string;
-    eventType: string;
-    targetEl?: string;
-    targetUrl?: string;
-    metadata?: Record<string, any>;
-    ts: number;
-}) => {
-    const p = await getProducer();
-    // add to the metadata
-    await p.send({
-        topic: 'user-interactions',
-        messages: [{
-            key: ev.sessionId,
-            value: JSON.stringify(ev),
-        }],
-    });
-};
-
-export const disconnect = async () => {
-    if (producer) {
-        await producer.disconnect();
-        producer = null;
-    }
-};

web/src/lib/sessionStore.ts

@@ -0,0 +1,102 @@
+type SessionData = {
+  experimentId?: string;
+  startedAt: number;
+  status: 'active' | 'stopped';
+};
+
+type ExperimentData = {
+  id: string;
+  status: 'active' | 'stopped';
+  sessionIds: string[];
+  createdAt: number;
+};
+
+const store = new Map<string, SessionData>();
+const experiments = new Map<string, ExperimentData>();
+
+const cfg = {
+  key: process.env.AIRTABLE_API_KEY,
+  base: process.env.AIRTABLE_BASE_ID,
+  table: process.env.AIRTABLE_TABLE_NAME || 'Sessions',
+};
+
+// sync session to airtable if credentials present
+const syncToAirtable = async (sid: string, data: SessionData) => {
+  if (!cfg.key || !cfg.base) return; // skip if not configured
+
+  try {
+    const url = `https://api.airtable.com/v0/${cfg.base}/${encodeURIComponent(cfg.table)}`;
+    await fetch(url, {
+      method: 'POST',
+      headers: {
+        Authorization: `Bearer ${cfg.key}`,
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({
+        fields: {
+          sessionId: sid,
+          experimentId: data.experimentId || '',
+          startedAt: new Date(data.startedAt).toISOString(),
+          status: data.status,
+        },
+      }),
+    });
+  } catch (err) {
+    console.error('airtable sync failed:', err);
+  }
+};
+
+export const getSession = (sid: string) => store.get(sid);
+
+export const createSession = (sid: string) => {
+  const data: SessionData = { startedAt: Date.now(), status: 'active' };
+  store.set(sid, data);
+  syncToAirtable(sid, data); // async fire-and-forget
+  return data;
+};
+
+export const setExperiment = (sid: string, expId: string) => {
+  const data = store.get(sid) || createSession(sid);
+  data.experimentId = expId;
+  store.set(sid, data);
+  syncToAirtable(sid, data);
+  return data;
+};
+
+export const stopExperiment = (sid: string) => {
+  const data = store.get(sid);
+  if (data) {
+    data.status = 'stopped';
+    store.set(sid, data);
+    syncToAirtable(sid, data);
+  }
+  return data;
+};
+
+// experiment-level operations
+export const createExperiment = (sid: string, expId: string) => {
+  const exp: ExperimentData = {
+    id: expId,
+    status: 'active',
+    sessionIds: [sid],
+    createdAt: Date.now(),
+  };
+  experiments.set(expId, exp);
+  setExperiment(sid, expId); // link session to experiment
+  console.log(`experiment ${expId} started with session ${sid}`);
+  return exp;
+};
+
+export const stopExperimentById = (expId: string) => {
+  const exp = experiments.get(expId);
+  if (exp) {
+    exp.status = 'stopped';
+    experiments.set(expId, exp);
+    console.log(`experiment ${expId} stopped`);
+  }
+  return exp;
+};
+
+export const getExperiment = (expId: string) => experiments.get(expId);
+
+export const getAllExperiments = () => Array.from(experiments.values());

web/src/proxy.ts

@@ -0,0 +1,36 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+export function proxy(req: NextRequest) {
+    const mode = process.env.STORE_MODE;
+    const { pathname } = req.nextUrl;
+
+    // skip rewrites for api routes, admin routes, static files, and next internals
+    if (
+        pathname.startsWith('/api') ||
+        pathname.startsWith('/admin') ||
+        pathname.startsWith('/_next') ||
+        pathname.startsWith('/static') ||
+        pathname.includes('.')
+        // TODO: add robots.txt and sitemap.xml if needed here
+    ) {
+        return NextResponse.next();
+    }
+
+    // already prefixed with mode
+    if (pathname.startsWith(`/${mode}`)) {
+        return NextResponse.next();
+    }
+
+    // rewrite root and unprefixed paths to mode-specific route group
+    const url = req.nextUrl.clone();
+    url.pathname = `/${mode}${pathname === '/' ? '' : pathname}`;
+
+    return NextResponse.rewrite(url);
+}
+
+export const config = {
+    matcher: [
+        // match all paths except those starting with _next/static, _next/image, favicon.ico
+        '/((?!_next/static|_next/image|favicon.ico).*)',
+    ],
+};

web/src/styles/airline.css

@@ -1,25 +1,38 @@
 /* Airline Platform - Sky Blue Theme */
 
-:root[data-mode="airline"] {
+@layer base {
+[data-mode="airline"] {
   --accent-primary: #007aff;
   --accent-secondary: #4caf50;
   --accent-warning: #ff3b30;
   --accent-primary-hover: #0051d5;
   --accent-primary-light: #e6f2ff;
   --text-accent: #007aff;
+  --hero-bg: linear-gradient(to bottom, white, #e6f2ff);
+}
 }
 
+@layer components {
 [data-mode="airline"] {
   --primary-color: var(--accent-primary);
 }
 
 [data-mode="airline"] .btn-primary {
-  background-color: var(--accent-primary);
-  color: #ffffff;
+  background-color: var(--accent-primary) !important;
+  color: #ffffff !important;
+  padding: 12px 24px;
+  font-weight: 600;
+  font-size: 1rem;
+  border-radius: var(--border-radius);
+  border: none;
+  cursor: pointer;
+  transition: all 0.2s ease;
 }
 
 [data-mode="airline"] .btn-primary:hover {
   background-color: var(--accent-primary-hover);
+  transform: translateY(-1px);
+  box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
 }
 
 [data-mode="airline"] .btn-secondary {
@@ -264,6 +277,7 @@
   border-radius: 6px;
   padding: 12px;
   transition: border-color 0.2s ease;
+  width: 100%;
 }
 
 [data-mode="airline"] .input-field:focus {
@@ -300,3 +314,8 @@
 [data-mode="airline"] .checkbox-label:hover {
   color: var(--accent-primary);
 }
+
+[data-mode="airline"] .hero-section {
+  background: var(--hero-bg);
+}
+}

web/src/styles/hotel.css

@@ -1,6 +1,7 @@
 /* Hotel Platform - Action Blue Theme */
 
-:root[data-mode="hotel"] {
+@layer base {
+[data-mode="hotel"] {
   --accent-primary: #007aff;
   --accent-secondary: #4caf50;
   --accent-warning: #d9534f;
@@ -8,8 +9,11 @@
   --accent-primary-light: #e6f2ff;
   --text-accent: #007aff;
   --bg-tertiary: #f5f5f7;
+  --hero-bg: linear-gradient(to bottom, white, #f5f5f5);
+}
 }
 
+@layer components {
 [data-mode="hotel"] {
   --primary-color: var(--accent-primary);
 }
@@ -17,10 +21,19 @@
 [data-mode="hotel"] .btn-primary {
   background-color: var(--accent-primary);
   color: #ffffff;
+  padding: 12px 24px;
+  font-weight: 600;
+  font-size: 1rem;
+  border-radius: var(--border-radius);
+  border: none;
+  cursor: pointer;
+  transition: all 0.2s ease;
 }
 
 [data-mode="hotel"] .btn-primary:hover {
   background-color: var(--accent-primary-hover);
+  transform: translateY(-1px);
+  box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
 }
 
 [data-mode="hotel"] .btn-secondary {
@@ -398,3 +411,8 @@
   color: var(--accent-primary);
   border-bottom-color: var(--accent-primary);
 }
+
+[data-mode="hotel"] .hero-section {
+  background: var(--hero-bg);
+}
+}