diff --git a/config.py b/config.py
new file mode 100644
index 0000000..7bb3682
--- /dev/null
+++ b/config.py
@@ -0,0 +1,26 @@
+"""Application configuration."""
+import os
+from pathlib import Path
+
+# Project root (parent of ``kernel_ai`` package)
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+
+
+class Config:
+    """Flask config loaded via app.config.from_object(Config)."""
+
+    DEBUG = os.getenv("FLASK_DEBUG", "False").lower() == "true"
+    ENV = os.getenv("FLASK_ENV", "production" if not DEBUG else "development")
+    STATIC_FOLDER = "static"
+    TEMPLATES_FOLDER = "templates"
+    API_PREFIX = "/api"
+    SEND_FILE_MAX_AGE_DEFAULT = 0 if not DEBUG else 31536000
+    PROJECT_ROOT = PROJECT_ROOT
+    LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO")
+    LOG_FORMAT = os.getenv("LOG_FORMAT", "json")
+    LOG_SERVICE_NAME = os.getenv("LOG_SERVICE_NAME", "kernel-ai-backend")
+    SENTRY_DSN = os.getenv("SENTRY_DSN", "").strip()
+    SENTRY_ENVIRONMENT = os.getenv("SENTRY_ENVIRONMENT", ENV)
+    SENTRY_RELEASE = os.getenv("SENTRY_RELEASE", "").strip() or None
+    SENTRY_SEND_DEFAULT_PII = os.getenv("SENTRY_SEND_DEFAULT_PII", "false").lower() == "true"
+    SENTRY_TRACES_SAMPLE_RATE = float(os.getenv("SENTRY_TRACES_SAMPLE_RATE", "0.0"))
diff --git a/sentry_setup.py b/sentry_setup.py
new file mode 100644
index 0000000..9fef07c
--- /dev/null
+++ b/sentry_setup.py
@@ -0,0 +1,36 @@
+"""Sentry initialization helpers for Flask app."""
+
+from __future__ import annotations
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+def init_sentry(app) -> bool:
+    """Initialize Sentry from app config.
+
+    Returns True when initialization succeeds and False otherwise.
+    """
+    dsn = str(app.config.get("SENTRY_DSN", "") or "").strip()
+    if not dsn:
+        logger.info("Sentry disabled: SENTRY_DSN is empty")
+        return False
+
+    try:
+        import sentry_sdk
+        from sentry_sdk.integrations.flask import FlaskIntegration
+    except Exception as exc:  # pragma: no cover - import failure is deployment issue
+        logger.warning("Sentry SDK not available: %s", exc)
+        return False
+
+    sentry_sdk.init(
+        dsn=dsn,
+        integrations=[FlaskIntegration()],
+        environment=app.config.get("SENTRY_ENVIRONMENT"),
+        release=app.config.get("SENTRY_RELEASE"),
+        send_default_pii=bool(app.config.get("SENTRY_SEND_DEFAULT_PII", False)),
+        traces_sample_rate=float(app.config.get("SENTRY_TRACES_SAMPLE_RATE", 0.0)),
+    )
+    logger.info("Sentry initialized")
+    return True
diff --git a/webapp.py b/webapp.py
new file mode 100644
index 0000000..0070543
--- /dev/null
+++ b/webapp.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+"""
+Linux Kernel Visualization Backend
+Thin Flask bootstrap module.
+"""
+
+import os
+import logging
+from flask import Flask, jsonify
+
+from kernel_ai.config import Config
+from kernel_ai.hooks import register_hooks
+from kernel_ai.http.common import build_error_payload
+from kernel_ai.http.register import register_http_routes
+from kernel_ai.logging_helpers import log_event
+from kernel_ai.logging_setup import configure_logging
+from kernel_ai.prometheus_setup import init_prometheus
+from kernel_ai.sentry_setup import init_sentry
+from kernel_ai.state import attach_state_container
+
+logger = logging.getLogger(__name__)
+
+def _ensure_prometheus_mpdir():
+    # Gunicorn -w N: set PROMETHEUS_MULTIPROC_DIR before workers import this module.
+    if os.environ.get("PROMETHEUS_MULTIPROC_DIR", "").strip():
+        _prom_mpdir = os.environ["PROMETHEUS_MULTIPROC_DIR"].strip()
+        os.makedirs(_prom_mpdir, exist_ok=True)
+
+
+def _register_error_handlers(app):
+    @app.errorhandler(404)
+    def not_found(error):
+        return jsonify(build_error_payload("Not found", "not_found")), 404
+
+    @app.errorhandler(500)
+    def internal_error(error):
+        return jsonify(build_error_payload("Internal server error", "internal_error")), 500
+
+
+def create_app():
+    """Application factory that builds and configures a Flask instance."""
+    _ensure_prometheus_mpdir()
+    root = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
+    app = Flask(
+        __name__,
+        static_folder=os.path.join(root, "static"),
+        template_folder=os.path.join(root, "templates"),
+    )
+    app.config.from_object(Config)
+    configure_logging(app)
+    sentry_enabled = init_sentry(app)
+    log_event(
+        logger,
+        "INFO",
+        "app_startup",
+        event_dataset="kernel_ai.app",
+        component="webapp",
+        operation="create_app",
+        event_data={
+            "service.environment": app.config.get("ENV", "production"),
+            "debug": bool(app.config.get("DEBUG", False)),
+            "api_prefix": app.config.get("API_PREFIX", "/api"),
+            "prometheus_multiproc_enabled": bool(
+                os.environ.get("PROMETHEUS_MULTIPROC_DIR", "").strip()
+            ),
+            "log_level": app.config.get("LOG_LEVEL"),
+            "log_format": app.config.get("LOG_FORMAT"),
+            "sentry_enabled": sentry_enabled,
+        },
+    )
+    attach_state_container(app)
+    init_prometheus(app)
+    register_hooks(app)
+    register_http_routes(app)
+    _register_error_handlers(app)
+    return app
+
+
+# Keep module-level app for Gunicorn and backward-compatible imports.
+app = create_app()