feat: add in-app release notes and what's new dialog

PROJECT_KNOWLEDGE.md

@@ -16,6 +16,10 @@ Backend:
 - HTTP Basic Auth is implemented with `Flask-HTTPAuth`.
 - Users are currently configured in `BETA_USERS` with Werkzeug password hashes.
 - `/` renders the active calculator template.
+- `/help` renders the authenticated Help landing page.
+- `/help/user-manual` renders `docs/de/user_manual.md` server-side inside the RollCalc Help layout.
+- `/help/recent-changes` renders `docs/de/recent_changes.md` server-side inside the RollCalc Help layout.
+- `/help/user-manual/screenshots/<path:filename>` serves German manual screenshots from `docs/de/screenshots/`.
 - `/static/<path:filename>` is intended to serve static files behind Basic Auth.
 - `/api/health` returns health/version information.
 - `/api/user` returns the authenticated user.
@@ -50,6 +54,54 @@ If `build_info.json` is missing, malformed, or does not contain a usable value,
 
 The data is loaded centrally in `app.py` and made available to every template as `build_info`.
 
+## Help and User Manual
+
+The in-app Help area keeps `docs/de/user_manual.md` as the leading German documentation source. RollCalc reads the Markdown file on each `/help/user-manual` request and renders it server-side with `markdown-it-py`.
+
+The documentation structure is prepared for language-specific manuals:
+
+```text
+docs/
+  de/
+    user_manual.md
+    screenshots/
+```
+
+Additional languages can follow the same structure later. The current public route still opens the German manual and no language switcher is implemented.
+
+Rendering rules:
+
+- Raw HTML from the Markdown source is disabled.
+- Heading ids and the table of contents are generated from the Markdown content.
+- Relative image references such as `screenshots/disclaimer.png` are rewritten to the authenticated manual screenshot route.
+- Screenshots belong in the active language's `screenshots/` directory, currently `docs/de/screenshots/`; the screenshot route must remain limited to that directory.
+
+The Help pages use the same HTTP Basic Auth protection as the calculator.
+
+### Recent Changes and What's New
+
+Full user-facing release notes are maintained in:
+
+```text
+docs/de/recent_changes.md
+```
+
+The calculator header links directly to `/help/user-manual`. The Help landing page lists only existing documents, currently User Manual and Recent Changes.
+
+The startup What's New dialog uses `build_info.version` and is suppressed when the version is empty or `unknown`. The last acknowledged version is stored only in browser `localStorage` under:
+
+```text
+rollcalc_last_seen_version
+```
+
+The short dialog item list is maintained separately in:
+
+```text
+static/recent_changes.json
+```
+
+This JSON is a compact summary for the dialog, not the complete release history. Keep it aligned with the most relevant current entries from `docs/de/recent_changes.md`.
+
 ## Authentication
 
 RollCalc uses HTTP Basic Auth. User entries in `BETA_USERS` have this shape:

README.md

@@ -9,6 +9,7 @@ This README is intended for developers maintaining the project, not for end user
 - Python 3
 - Flask 2.3.3
 - Flask-HTTPAuth 4.8.0
+- markdown-it-py 3.0.0 for server-side Markdown rendering
 - Vanilla HTML, CSS, and JavaScript
 - JSON files for product data and forklift/load rules
 
@@ -58,7 +59,9 @@ The app uses HTTP Basic Auth. Current users are defined in `BETA_USERS` in `app.
 ├── fix_article_data.py
 ├── service-worker.js
 ├── templates/
-│   └── roll_calculator.html
+│   ├── help_index.html
+│   ├── roll_calculator.html
+│   └── user_manual.html
 ├── static/
 │   ├── article-data.json
 │   ├── config.json
@@ -71,6 +74,9 @@ The app uses HTTP Basic Auth. Current users are defined in `BETA_USERS` in `app.
 │   ├── rollcalc_stddev_ranges.js
 │   └── rollcalc_stddev_integration.js
 └── docs/
+    ├── de/
+    │   ├── screenshots/
+    │   └── user_manual.md
     ├── DEPLOYMENT_GUIDE.md
     ├── QOL_UPDATE_SUMMARY.md
     ├── STDDEV_IMPLEMENTATION_CHECKLIST.md
@@ -86,6 +92,10 @@ Implemented routes:
 | Route | Methods | Auth | Purpose |
 | --- | --- | --- | --- |
 | `/` | `GET` | Basic Auth | Renders `templates/roll_calculator.html`. |
+| `/help` | `GET` | Basic Auth | Renders the Help landing page. |
+| `/help/user-manual` | `GET` | Basic Auth | Reads `docs/de/user_manual.md`, renders it as HTML, and displays it in the RollCalc Help layout. |
+| `/help/recent-changes` | `GET` | Basic Auth | Reads `docs/de/recent_changes.md`, renders it as HTML, and displays it in the RollCalc Help layout. |
+| `/help/user-manual/screenshots/<path:filename>` | `GET` | Basic Auth | Serves German user-manual screenshots from `docs/de/screenshots/` only. |
 | `/static/<path:filename>` | `GET` | Basic Auth | Intended protected static-file serving from `static/`. |
 | `/api/health` | `GET` | Basic Auth | Returns app health and version. |
 | `/api/user` | `GET` | Basic Auth | Returns current authenticated user info. |
@@ -109,6 +119,67 @@ Do not commit real passwords or print them in logs.
 
 Access logging is handled by `log_access()`, which reads `access_log.json`, appends a record, and writes the whole file back.
 
+## Help and User Manual
+
+RollCalc exposes an authenticated Help area at:
+
+```text
+/help
+```
+
+The user manual is available at:
+
+```text
+/help/user-manual
+```
+
+Recent changes are available at:
+
+```text
+/help/recent-changes
+```
+
+`docs/de/user_manual.md` is the leading source for the German user manual. The app reads this Markdown file on request and renders it server-side with `markdown-it-py`; no generated static HTML copy is maintained. Raw HTML in the Markdown source is disabled during rendering.
+
+`docs/de/recent_changes.md` is the leading source for full German release notes. It is rendered through the same authenticated Markdown infrastructure.
+
+The documentation directory is prepared for additional languages:
+
+```text
+docs/
+  de/
+    user_manual.md
+    screenshots/
+```
+
+The public route `/help/user-manual` currently opens the German manual. No language switcher is implemented yet.
+
+Screenshots referenced from the manual as `screenshots/filename.png` should be placed in:
+
+```text
+docs/de/screenshots/
+```
+
+The application rewrites those relative Markdown image paths to the authenticated manual screenshot route, which is limited to the active language's screenshot directory.
+
+### What's New Dialog
+
+The calculator page shows a compact What's New dialog once per build version. The current version comes from `build_info.version`; if that value is empty or `unknown`, the dialog is not shown.
+
+The last acknowledged version is stored only in the browser:
+
+```text
+rollcalc_last_seen_version
+```
+
+The short dialog summary is maintained in:
+
+```text
+static/recent_changes.json
+```
+
+Keep `docs/de/recent_changes.md` as the complete release-note source and `static/recent_changes.json` as the short 3-5 item summary for the startup dialog.
+
 ## Frontend Entry Point
 
 The active UI is `templates/roll_calculator.html`.

app.py

@@ -3,13 +3,27 @@ Naue Roll Calculator - Beta
 Flask app with HTTP Basic Authentication
 """
 
-from flask import Flask, render_template, request, send_file, send_from_directory, jsonify
+from flask import (
+    Flask,
+    abort,
+    jsonify,
+    render_template,
+    request,
+    send_file,
+    send_from_directory,
+    url_for,
+)
 from flask_httpauth import HTTPBasicAuth
+from markdown_it import MarkdownIt
+from markupsafe import Markup
 from werkzeug.security import check_password_hash
 from functools import wraps
 import os
 from datetime import datetime
 import json
+import re
+import socket
+import unicodedata
 
 app = Flask(__name__)
 auth = HTTPBasicAuth()
@@ -43,6 +57,11 @@ BETA_USERS = {
 # Logging für Auditing
 LOG_FILE = "access_log.json"
 BUILD_INFO_FILE = "build_info.json"
+DOCS_DIR = os.path.join(app.root_path, "docs")
+DEFAULT_DOC_LANGUAGE = "de"
+USER_MANUAL_FILENAME = "user_manual.md"
+RECENT_CHANGES_FILENAME = "recent_changes.md"
+WHATS_NEW_SUMMARY_FILE = os.path.join(app.root_path, "static", "recent_changes.json")
 UNKNOWN_BUILD_INFO = {
     "version": "unknown",
     "branch": "unknown",
@@ -75,10 +94,36 @@ def load_build_info():
 
 BUILD_INFO = load_build_info()
 
+
+def load_whats_new_summary():
+    """Load compact release notes for the What's New dialog."""
+    try:
+        with open(WHATS_NEW_SUMMARY_FILE, "r", encoding="utf-8") as f:
+            data = json.load(f)
+    except Exception as e:
+        print(f"[What's New Error] {e}")
+        return []
+
+    items = data.get("items") if isinstance(data, dict) else None
+    if not isinstance(items, list):
+        return []
+
+    return [
+        item.strip()
+        for item in items
+        if isinstance(item, str) and item.strip()
+    ][:5]
+
+
+WHATS_NEW_SUMMARY = load_whats_new_summary()
+
 @app.context_processor
 def inject_build_info():
-    """Make build metadata available in all templates."""
-    return {"build_info": BUILD_INFO}
+    """Make build metadata and release-note summary available in templates."""
+    return {
+        "build_info": BUILD_INFO,
+        "whats_new_summary": WHATS_NEW_SUMMARY
+    }
 
 # ============================================================================
 # AUTHENTICATION
@@ -116,10 +161,119 @@ def log_access(username, endpoint, method, status=200):
     except Exception as e:
         print(f"[Logging Error] {e}")
 
+
+def find_free_port(start_port=5000, max_attempts=10, host="0.0.0.0"):
+    """Find the first available TCP port at or above start_port."""
+    for port in range(start_port, start_port + max_attempts):
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            try:
+                sock.bind((host, port))
+            except OSError:
+                continue
+            return port
+
+    raise RuntimeError(
+        f"No free port found from {start_port} to "
+        f"{start_port + max_attempts - 1}"
+    )
+
 # ============================================================================
 # ROUTES
 # ============================================================================
 
+def slugify_heading(text):
+    """Create stable, URL-friendly heading ids for rendered Markdown."""
+    normalized = unicodedata.normalize("NFKD", text)
+    ascii_text = normalized.encode("ascii", "ignore").decode("ascii")
+    slug = re.sub(r"[^a-zA-Z0-9]+", "-", ascii_text).strip("-").lower()
+    return slug or "section"
+
+
+def build_manual_renderer():
+    """Build a Markdown renderer with raw HTML disabled."""
+    renderer = MarkdownIt("commonmark", {"html": False})
+    renderer.enable("table")
+    return renderer
+
+
+def get_document_path(filename, language=DEFAULT_DOC_LANGUAGE):
+    """Return the Markdown path for a language-specific help document."""
+    return os.path.join(DOCS_DIR, language, filename)
+
+
+def get_manual_path(language=DEFAULT_DOC_LANGUAGE):
+    """Return the Markdown path for a language-specific manual."""
+    return get_document_path(USER_MANUAL_FILENAME, language)
+
+
+def get_manual_screenshot_dir(language=DEFAULT_DOC_LANGUAGE):
+    """Return the screenshot directory for a language-specific manual."""
+    return os.path.join(DOCS_DIR, language, "screenshots")
+
+
+def rewrite_manual_asset_paths(markdown_text, language=DEFAULT_DOC_LANGUAGE):
+    """Route relative manual screenshot links through the protected docs route."""
+    screenshot_url = url_for("manual_screenshot", filename="")
+    return markdown_text.replace("](screenshots/", f"]({screenshot_url}")
+
+
+def add_heading_ids_and_toc(tokens):
+    """Attach ids to headings and create a compact table of contents."""
+    toc = []
+    used_slugs = {}
+
+    for index, token in enumerate(tokens):
+        if token.type != "heading_open":
+            continue
+
+        level = int(token.tag[1])
+        inline_token = tokens[index + 1] if index + 1 < len(tokens) else None
+        title = (
+            inline_token.content
+            if inline_token and inline_token.type == "inline"
+            else ""
+        )
+        base_slug = slugify_heading(title)
+        count = used_slugs.get(base_slug, 0)
+        used_slugs[base_slug] = count + 1
+        slug = base_slug if count == 0 else f"{base_slug}-{count + 1}"
+        token.attrSet("id", slug)
+
+        if level <= 2:
+            toc.append({
+                "level": level,
+                "title": title,
+                "id": slug
+            })
+
+    return toc
+
+
+def render_markdown_document(filename, language=DEFAULT_DOC_LANGUAGE):
+    """Read and render a Markdown help document into HTML and a generated TOC."""
+    renderer = build_manual_renderer()
+    document_path = get_document_path(filename, language)
+
+    with open(document_path, "r", encoding="utf-8") as document_file:
+        markdown_text = document_file.read()
+
+    markdown_text = rewrite_manual_asset_paths(markdown_text, language)
+    tokens = renderer.parse(markdown_text)
+    toc = add_heading_ids_and_toc(tokens)
+    html = renderer.renderer.render(tokens, renderer.options, {})
+    return Markup(html), toc
+
+
+def render_user_manual(language=DEFAULT_DOC_LANGUAGE):
+    """Read and render the Markdown user manual."""
+    return render_markdown_document(USER_MANUAL_FILENAME, language)
+
+
+def render_recent_changes(language=DEFAULT_DOC_LANGUAGE):
+    """Read and render the Markdown recent changes document."""
+    return render_markdown_document(RECENT_CHANGES_FILENAME, language)
+
 @app.route("/", methods=["GET"])
 @auth.login_required
 def index():
@@ -127,6 +281,92 @@ def index():
     log_access(auth.current_user(), "/", "GET")
     return render_template("roll_calculator.html")
 
+@app.route("/help", methods=["GET"])
+@auth.login_required
+def help_index():
+    """Help landing page - requires authentication."""
+    log_access(auth.current_user(), "/help", "GET")
+    return render_template("help_index.html")
+
+@app.route("/help/user-manual", methods=["GET"])
+@auth.login_required
+def user_manual():
+    """Render the Markdown user manual inside the RollCalc layout."""
+    log_access(auth.current_user(), "/help/user-manual", "GET")
+    try:
+        manual_html, toc = render_user_manual(DEFAULT_DOC_LANGUAGE)
+        return render_template(
+            "user_manual.html",
+            document_title="User Manual",
+            document_subtitle="RollCalc technical user documentation",
+            error_title="User Manual unavailable",
+            manual_html=manual_html,
+            toc=toc,
+            render_error=None
+        )
+    except Exception:
+        app.logger.exception("Could not render user manual")
+        return render_template(
+            "user_manual.html",
+            document_title="User Manual",
+            document_subtitle="RollCalc technical user documentation",
+            error_title="User Manual unavailable",
+            manual_html=None,
+            toc=[],
+            render_error=(
+                "The user manual could not be loaded. "
+                "Please contact the RollCalc maintainer if the problem persists."
+            )
+        ), 500
+
+
+@app.route("/help/recent-changes", methods=["GET"])
+@auth.login_required
+def recent_changes():
+    """Render recent changes inside the RollCalc Help layout."""
+    log_access(auth.current_user(), "/help/recent-changes", "GET")
+    try:
+        changes_html, toc = render_recent_changes(DEFAULT_DOC_LANGUAGE)
+        return render_template(
+            "user_manual.html",
+            document_title="Recent Changes",
+            document_subtitle="RollCalc release notes",
+            error_title="Recent Changes unavailable",
+            manual_html=changes_html,
+            toc=toc,
+            render_error=None
+        )
+    except Exception:
+        app.logger.exception("Could not render recent changes")
+        return render_template(
+            "user_manual.html",
+            document_title="Recent Changes",
+            document_subtitle="RollCalc release notes",
+            error_title="Recent Changes unavailable",
+            manual_html=None,
+            toc=[],
+            render_error=(
+                "Recent changes could not be loaded. "
+                "Please contact the RollCalc maintainer if the problem persists."
+            )
+        ), 500
+
+
+@app.route("/help/user-manual/screenshots/<path:filename>", methods=["GET"])
+@auth.login_required
+def manual_screenshot(filename, language=DEFAULT_DOC_LANGUAGE):
+    """Serve user-manual screenshots from the selected language directory."""
+    log_access(
+        auth.current_user(),
+        f"/help/user-manual/screenshots/{filename}",
+        "GET"
+    )
+    try:
+        return send_from_directory(get_manual_screenshot_dir(language), filename)
+    except Exception:
+        app.logger.warning("Missing or inaccessible manual screenshot: %s", filename)
+        abort(404)
+
 @app.route("/static/<path:filename>", methods=["GET"])
 @auth.login_required
 def serve_static(filename):
@@ -177,21 +417,22 @@ def internal_error(e):
 if __name__ == "__main__":
     os.makedirs("templates", exist_ok=True)
     os.makedirs("static", exist_ok=True)
+    port = find_free_port(start_port=5000, max_attempts=10, host="0.0.0.0")
     
-    print("""
+    print(f"""
     ╔═══════════════════════════════════════════════════════════╗
     ║  Naue Roll Calculator - V14 + QoL Update                 ║
     ║  HTTP Basic Auth Enabled                                 ║
     ║                                                           ║
     ║  ⚠️  BEFORE PRODUCTION: Update passwords in app.py       ║
     ║                                                           ║
-    ║  Starten auf: http://localhost:5000                     ║
+    ║  Starten auf: http://localhost:{port:<5}                    ║
     ╚═══════════════════════════════════════════════════════════╝
     """)
     
     app.run(
         host="0.0.0.0",
-        port=5000,
+        port=port,
         debug=False,
         use_reloader=False
     )

docs/de/recent_changes.md

@@ -0,0 +1,9 @@
+# Recent Changes
+
+## Version 0.4
+
+- User Manual integrated into RollCalc.
+- Help area added for internal documentation.
+- Capacity Analysis presentation improved.
+- Governing Constraint highlighted more clearly.
+- Remaining Capacity added to the Capacity Summary.

requirements.txt

@@ -5,3 +5,4 @@ click==8.1.7
 itsdangerous==2.1.2
 Jinja2==3.1.2
 MarkupSafe==2.1.3
+markdown-it-py==3.0.0

static/recent_changes.json

@@ -0,0 +1,8 @@
+{
+  "items": [
+    "User Manual integrated",
+    "Capacity Analysis improved",
+    "Governing Constraint clarified",
+    "Remaining Capacity added"
+  ]
+}

templates/help_index.html

@@ -0,0 +1,80 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <meta name="description" content="RollCalc Help">
+  <title>RollCalc Help</title>
+  <style>
+    * { box-sizing: border-box; margin: 0; padding: 0; }
+    body { font-family: 'Segoe UI', Arial, sans-serif; background: #f4f6f9; color: #2f3437; min-height: 100vh; }
+    .help-header { background: linear-gradient(135deg, #1F5438 0%, #2BAC70 100%); color: #fff; padding: 20px 32px; box-shadow: 0 2px 8px rgba(0,0,0,0.2); }
+    .help-header-inner { max-width: 980px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 18px; }
+    .help-header h1 { font-size: 24px; margin-bottom: 5px; }
+    .help-header p { font-size: 13px; opacity: 0.9; }
+    .help-nav { display: flex; gap: 10px; flex-wrap: wrap; }
+    .help-nav a { color: #fff; border: 1px solid rgba(255,255,255,0.58); border-radius: 5px; padding: 7px 13px; text-decoration: none; font-size: 13px; font-weight: 700; background: rgba(255,255,255,0.08); }
+    .help-nav a:hover { background: rgba(255,255,255,0.18); }
+    .help-container { max-width: 980px; margin: 30px auto; padding: 0 16px 60px; }
+    .help-intro { margin-bottom: 22px; line-height: 1.55; color: #4b555a; }
+    .help-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 18px; }
+    .help-card { background: #fff; border: 1px solid #dfe7e2; border-radius: 8px; padding: 20px; box-shadow: 0 2px 12px rgba(0,0,0,0.06); }
+    .help-card h2 { color: #1F5438; font-size: 18px; margin-bottom: 10px; }
+    .help-card p { color: #4f5b60; font-size: 14px; line-height: 1.55; margin-bottom: 18px; }
+    .help-card a { display: inline-block; background: #2BAC70; color: #fff; text-decoration: none; border-radius: 6px; padding: 10px 16px; font-size: 14px; font-weight: 700; }
+    .help-card a:hover { background: #1F5438; }
+    .footer { text-align: center; font-size: 11px; color: #aaa; padding: 18px; }
+    .footer-build-info { margin-top: 6px; color: #bbb; }
+    @media (max-width: 640px) {
+      .help-header { padding: 18px 16px; }
+      .help-header-inner { align-items: flex-start; flex-direction: column; }
+    }
+  </style>
+</head>
+<body>
+  <header class="help-header">
+    <div class="help-header-inner">
+      <div>
+        <h1>RollCalc Help</h1>
+        <p>Documentation for roll calculation and transport capacity analysis</p>
+      </div>
+      <nav class="help-nav" aria-label="Help navigation">
+        <a href="{{ url_for('index') }}">Calculator</a>
+      </nav>
+    </div>
+  </header>
+
+  <main class="help-container">
+    <p class="help-intro">
+      This area provides internal technical documentation for RollCalc. The documents are rendered from the maintained Markdown sources.
+    </p>
+
+    <section class="help-grid" aria-label="Available help documents">
+      <article class="help-card">
+        <h2>User Manual</h2>
+        <p>
+          Workflow-oriented manual for roll calculation, handling evaluation, Load Optimizer usage, and interpretation of Capacity Summary and Capacity Analysis.
+        </p>
+        <a href="{{ url_for('user_manual') }}">Open User Manual</a>
+      </article>
+      <article class="help-card">
+        <h2>Recent Changes</h2>
+        <p>
+          Compact release notes for relevant user-facing changes in RollCalc.
+        </p>
+        <a href="{{ url_for('recent_changes') }}">Open Recent Changes</a>
+      </article>
+    </section>
+  </main>
+
+  <footer class="footer">
+    RollCalc Beta &copy; Naue
+    <div class="footer-build-info">
+      Version {{ build_info.version }} |
+      Branch {{ build_info.branch }} |
+      Commit {{ build_info.commit }} |
+      Built {{ build_info.timestamp }}
+    </div>
+  </footer>
+</body>
+</html>

templates/roll_calculator.html

@@ -9,8 +9,11 @@
     * { box-sizing: border-box; margin: 0; padding: 0; }
     body { font-family: 'Segoe UI', Arial, sans-serif; background: #f4f6f9; color: #333; min-height: 100vh; }
     .header { background: linear-gradient(135deg, #1F5438 0%, #2BAC70 100%); color: #fff; padding: 20px 32px; box-shadow: 0 2px 8px rgba(0,0,0,0.2); }
+    .header-inner { max-width: 900px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 18px; }
     .header h1 { font-size: 24px; margin-bottom: 5px; }
     .header p { font-size: 13px; opacity: 0.9; }
+    .header-help-link { color: #fff; border: 1px solid rgba(255,255,255,0.58); border-radius: 5px; padding: 7px 13px; text-decoration: none; font-size: 13px; font-weight: 700; background: rgba(255,255,255,0.08); }
+    .header-help-link:hover { background: rgba(255,255,255,0.18); }
     .container { max-width: 900px; margin: 30px auto; padding: 0 16px 60px; }
     .card { background: #fff; border-radius: 10px; box-shadow: 0 2px 12px rgba(0,0,0,0.07); margin-bottom: 24px; overflow: hidden; }
     .card-header { background: #f0f4fa; padding: 16px 22px; border-bottom: 1px solid #e0e8f0; }
@@ -143,6 +146,59 @@
       background: #b8c7bf;
       cursor: not-allowed;
     }
+    .whats-new-overlay {
+      position: fixed;
+      inset: 0;
+      z-index: 9000;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      padding: 20px;
+      background: rgba(20, 28, 34, 0.55);
+    }
+    .whats-new-overlay.is-hidden { display: none; }
+    .whats-new-dialog {
+      width: min(520px, 100%);
+      background: #fff;
+      border-radius: 8px;
+      box-shadow: 0 18px 42px rgba(0, 0, 0, 0.24);
+      overflow: hidden;
+    }
+    .whats-new-header {
+      padding: 16px 20px;
+      background: #1F5438;
+      color: #fff;
+    }
+    .whats-new-header h2 { font-size: 18px; margin: 0 0 4px; }
+    .whats-new-version { font-size: 12px; opacity: 0.88; }
+    .whats-new-content {
+      padding: 18px 20px 8px;
+      font-size: 14px;
+      line-height: 1.5;
+      color: #333;
+    }
+    .whats-new-content ul { margin: 8px 0 0 20px; }
+    .whats-new-content li { margin-bottom: 5px; }
+    .whats-new-actions {
+      display: flex;
+      justify-content: flex-end;
+      gap: 10px;
+      padding: 16px 20px 18px;
+      border-top: 1px solid #e0e8f0;
+      background: #f8fafa;
+    }
+    .whats-new-btn {
+      border: none;
+      border-radius: 6px;
+      padding: 9px 14px;
+      font-size: 13px;
+      font-weight: 700;
+      cursor: pointer;
+    }
+    .whats-new-btn-primary { background: #2BAC70; color: #fff; }
+    .whats-new-btn-primary:hover { background: #1F5438; }
+    .whats-new-btn-secondary { background: #fff; color: #1F5438; border: 1px solid #a8c8ba; }
+    .whats-new-btn-secondary:hover { background: #eef4f1; }
 
     /* ============================================
        LOAD OPTIMIZER STYLES
@@ -448,6 +504,10 @@
     .margin-color    { background: repeating-linear-gradient(45deg,#fff7e0,#fff7e0 3px,#ffe8a0 3px,#ffe8a0 6px); border-color:#f0b429; }
 
     @media (max-width: 768px) {
+      .header { padding: 18px 16px; }
+      .header-inner { align-items: flex-start; }
+      .whats-new-actions { flex-direction: column; }
+      .whats-new-btn { width: 100%; }
       .lo-accordion-header h3 { font-size: 14px; }
       .lo-preset-buttons { flex-direction: column; }
       .lo-preset-btn { width: 100%; }
@@ -491,9 +551,30 @@
   </div>
 </div>
 
+<div class="whats-new-overlay is-hidden" id="whatsNewOverlay" role="dialog" aria-modal="true" aria-labelledby="whatsNewTitle">
+  <div class="whats-new-dialog">
+    <div class="whats-new-header">
+      <h2 id="whatsNewTitle">What’s New</h2>
+      <div class="whats-new-version">Version: <span id="whatsNewVersion">–</span></div>
+    </div>
+    <div class="whats-new-content">
+      <ul id="whatsNewList"></ul>
+    </div>
+    <div class="whats-new-actions">
+      <button class="whats-new-btn whats-new-btn-secondary" id="whatsNewOpenChangesBtn" type="button">Open Recent Changes</button>
+      <button class="whats-new-btn whats-new-btn-primary" id="whatsNewContinueBtn" type="button">Continue</button>
+    </div>
+  </div>
+</div>
+
 <div class="header">
-  <h1>Naue Roll Diameter Calculator</h1>
-  <p>Roll Diameter • Product Length • Roll Weight • Load Optimizer</p>
+  <div class="header-inner">
+    <div>
+      <h1>Naue Roll Diameter Calculator</h1>
+      <p>Roll Diameter • Product Length • Roll Weight • Load Optimizer</p>
+    </div>
+    <a class="header-help-link" href="{{ url_for('user_manual') }}">User Manual</a>
+  </div>
 </div>
 
 <div class="container">
@@ -1563,12 +1644,81 @@ document.addEventListener('DOMContentLoaded', () => {
   window.loadOptimizerUI = new LoadOptimizerUI();
 });
 
+const ROLLCALC_BUILD_VERSION = {{ build_info.version|tojson }};
+const ROLLCALC_WHATS_NEW_ITEMS = {{ whats_new_summary|tojson }};
+const ROLLCALC_LAST_SEEN_VERSION_KEY = 'rollcalc_last_seen_version';
+
+function shouldShowWhatsNew(currentVersion, storedVersion) {
+  return !!currentVersion &&
+    currentVersion !== 'unknown' &&
+    currentVersion !== storedVersion;
+}
+
+function markWhatsNewSeen(currentVersion) {
+  if (!currentVersion || currentVersion === 'unknown') return;
+  try {
+    localStorage.setItem(ROLLCALC_LAST_SEEN_VERSION_KEY, currentVersion);
+  } catch (e) {
+    console.warn('Could not store RollCalc release note state', e);
+  }
+}
+
+function renderWhatsNewItems(items) {
+  const list = document.getElementById('whatsNewList');
+  if (!list) return;
+
+  list.innerHTML = '';
+  items.forEach(item => {
+    const li = document.createElement('li');
+    li.textContent = item;
+    list.appendChild(li);
+  });
+}
+
+function maybeShowWhatsNew() {
+  const overlay = document.getElementById('whatsNewOverlay');
+  const versionValue = document.getElementById('whatsNewVersion');
+  const continueBtn = document.getElementById('whatsNewContinueBtn');
+  const openChangesBtn = document.getElementById('whatsNewOpenChangesBtn');
+  const items = Array.isArray(ROLLCALC_WHATS_NEW_ITEMS)
+    ? ROLLCALC_WHATS_NEW_ITEMS
+    : [];
+
+  if (!overlay || !versionValue || !continueBtn || !openChangesBtn || items.length === 0) return;
+
+  let storedVersion = null;
+  try {
+    storedVersion = localStorage.getItem(ROLLCALC_LAST_SEEN_VERSION_KEY);
+  } catch (e) {
+    storedVersion = null;
+  }
+
+  if (!shouldShowWhatsNew(ROLLCALC_BUILD_VERSION, storedVersion)) return;
+
+  versionValue.textContent = ROLLCALC_BUILD_VERSION;
+  renderWhatsNewItems(items);
+  overlay.classList.remove('is-hidden');
+
+  continueBtn.addEventListener('click', () => {
+    markWhatsNewSeen(ROLLCALC_BUILD_VERSION);
+    overlay.classList.add('is-hidden');
+  }, { once: true });
+
+  openChangesBtn.addEventListener('click', () => {
+    markWhatsNewSeen(ROLLCALC_BUILD_VERSION);
+    window.location.href = {{ url_for('recent_changes')|tojson }};
+  }, { once: true });
+}
+
 document.addEventListener('DOMContentLoaded', () => {
   const overlay = document.getElementById('disclaimerOverlay');
   const checkbox = document.getElementById('disclaimerAccepted');
   const confirmBtn = document.getElementById('disclaimerConfirmBtn');
 
-  if (!overlay || !checkbox || !confirmBtn) return;
+  if (!overlay || !checkbox || !confirmBtn) {
+    maybeShowWhatsNew();
+    return;
+  }
 
   checkbox.addEventListener('change', () => {
     confirmBtn.disabled = !checkbox.checked;
@@ -1577,6 +1727,7 @@ document.addEventListener('DOMContentLoaded', () => {
   confirmBtn.addEventListener('click', () => {
     if (!checkbox.checked) return;
     overlay.classList.add('is-hidden');
+    maybeShowWhatsNew();
   });
 });
 </script>

templates/user_manual.html

@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <meta name="description" content="RollCalc {{ document_title }}">
+  <title>RollCalc {{ document_title }}</title>
+  <style>
+    * { box-sizing: border-box; margin: 0; padding: 0; }
+    html { scroll-behavior: smooth; }
+    body { font-family: 'Segoe UI', Arial, sans-serif; background: #f4f6f9; color: #2f3437; min-height: 100vh; }
+    .help-header { background: linear-gradient(135deg, #1F5438 0%, #2BAC70 100%); color: #fff; padding: 20px 32px; box-shadow: 0 2px 8px rgba(0,0,0,0.2); }
+    .help-header-inner { max-width: 1180px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 18px; }
+    .help-header h1 { font-size: 24px; margin-bottom: 5px; }
+    .help-header p { font-size: 13px; opacity: 0.9; }
+    .help-nav { display: flex; gap: 10px; flex-wrap: wrap; }
+    .help-nav a { color: #fff; border: 1px solid rgba(255,255,255,0.58); border-radius: 5px; padding: 7px 13px; text-decoration: none; font-size: 13px; font-weight: 700; background: rgba(255,255,255,0.08); }
+    .help-nav a:hover { background: rgba(255,255,255,0.18); }
+    .manual-shell { max-width: 1180px; margin: 28px auto; padding: 0 16px 60px; }
+    .manual-layout { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 24px; align-items: start; }
+    .manual-toc { position: sticky; top: 18px; background: #fff; border: 1px solid #dfe7e2; border-radius: 8px; padding: 16px; box-shadow: 0 2px 12px rgba(0,0,0,0.05); max-height: calc(100vh - 36px); overflow: auto; }
+    .manual-toc h2 { color: #1F5438; font-size: 14px; margin-bottom: 12px; text-transform: uppercase; letter-spacing: 0; }
+    .manual-toc ul { list-style: none; }
+    .manual-toc li { margin: 0 0 8px; }
+    .manual-toc a { color: #34443b; text-decoration: none; font-size: 13px; line-height: 1.35; }
+    .manual-toc a:hover { color: #1F5438; text-decoration: underline; }
+    .manual-toc .toc-level-2 { padding-left: 14px; }
+    .manual-content { background: #fff; border: 1px solid #dfe7e2; border-radius: 8px; padding: 34px 42px; box-shadow: 0 2px 12px rgba(0,0,0,0.05); line-height: 1.62; font-size: 15px; }
+    .manual-content h1, .manual-content h2, .manual-content h3, .manual-content h4 { color: #1F5438; line-height: 1.25; scroll-margin-top: 18px; }
+    .manual-content h1 { font-size: 30px; margin: 0 0 24px; padding-bottom: 14px; border-bottom: 2px solid #dfe7e2; }
+    .manual-content h2 { font-size: 22px; margin: 34px 0 14px; padding-top: 4px; }
+    .manual-content h3 { font-size: 17px; margin: 26px 0 10px; color: #244b39; }
+    .manual-content h4 { font-size: 15px; margin: 20px 0 8px; color: #244b39; }
+    .manual-content p { margin: 0 0 14px; }
+    .manual-content ul, .manual-content ol { margin: 0 0 16px 24px; }
+    .manual-content li { margin: 5px 0; }
+    .manual-content a { color: #1F5438; font-weight: 600; }
+    .manual-content code { background: #eef4f1; border: 1px solid #d7e4de; border-radius: 4px; padding: 1px 4px; font-family: Consolas, 'Courier New', monospace; font-size: 0.92em; }
+    .manual-content pre { background: #f5f7f6; border: 1px solid #dfe7e2; border-radius: 6px; padding: 14px; margin: 16px 0; overflow-x: auto; }
+    .manual-content pre code { background: transparent; border: 0; padding: 0; }
+    .manual-content blockquote { margin: 18px 0; padding: 14px 18px; border-left: 4px solid #2BAC70; background: #f1f8f5; color: #34443b; }
+    .manual-content blockquote p:last-child, .manual-content blockquote ul:last-child { margin-bottom: 0; }
+    .manual-content table { width: 100%; border-collapse: collapse; margin: 18px 0; display: block; overflow-x: auto; }
+    .manual-content th, .manual-content td { border: 1px solid #d7e4de; padding: 9px 11px; text-align: left; vertical-align: top; }
+    .manual-content th { background: #eef4f1; color: #1F5438; }
+    .manual-content img { max-width: 100%; height: auto; border: 1px solid #dfe7e2; border-radius: 6px; background: #f8fafa; display: block; margin: 18px 0 8px; }
+    .manual-error { background: #fff; border: 1px solid #e6c7c7; border-left: 4px solid #b84a4a; border-radius: 8px; padding: 20px; color: #5a2d2d; box-shadow: 0 2px 12px rgba(0,0,0,0.05); }
+    .footer { text-align: center; font-size: 11px; color: #aaa; padding: 18px; }
+    .footer-build-info { margin-top: 6px; color: #bbb; }
+    @media (max-width: 840px) {
+      .help-header { padding: 18px 16px; }
+      .help-header-inner { align-items: flex-start; flex-direction: column; }
+      .manual-layout { grid-template-columns: 1fr; }
+      .manual-toc { position: static; max-height: none; }
+      .manual-content { padding: 24px 20px; }
+      .manual-content h1 { font-size: 25px; }
+      .manual-content h2 { font-size: 20px; }
+    }
+  </style>
+</head>
+<body>
+  <header class="help-header">
+    <div class="help-header-inner">
+      <div>
+        <h1>{{ document_title }}</h1>
+        <p>{{ document_subtitle }}</p>
+      </div>
+      <nav class="help-nav" aria-label="Help navigation">
+        <a href="{{ url_for('index') }}">Calculator</a>
+        <a href="{{ url_for('help_index') }}">Help</a>
+      </nav>
+    </div>
+  </header>
+
+  <main class="manual-shell">
+    {% if render_error %}
+      <section class="manual-error" role="alert">
+        <strong>{{ error_title }}</strong>
+        <p>{{ render_error }}</p>
+      </section>
+    {% else %}
+      <div class="manual-layout">
+        <nav class="manual-toc" aria-label="Table of contents">
+          <h2>Contents</h2>
+          <ul>
+            {% for entry in toc %}
+              <li class="toc-level-{{ entry.level }}">
+                <a href="#{{ entry.id }}">{{ entry.title }}</a>
+              </li>
+            {% endfor %}
+          </ul>
+        </nav>
+        <article class="manual-content">
+          {{ manual_html }}
+        </article>
+      </div>
+    {% endif %}
+  </main>
+
+  <footer class="footer">
+    RollCalc Beta &copy; Naue
+    <div class="footer-build-info">
+      Version {{ build_info.version }} |
+      Branch {{ build_info.branch }} |
+      Commit {{ build_info.commit }} |
+      Built {{ build_info.timestamp }}
+    </div>
+  </footer>
+</body>
+</html>