diff --git a/docs/artifact-registry.md b/docs/artifact-registry.md
index 5b3d158..dbed37f 100644
--- a/docs/artifact-registry.md
+++ b/docs/artifact-registry.md
@@ -15,7 +15,7 @@ document of a type. `Primary File` may contain a glob (e.g.
 | SA | Stakeholder Analysis | docs/stakeholder-analysis.md | 002 |
 | PP | Project Plan | docs/project-plan.md | 002 |
 | MIL | Milestone / Gateway | docs/milestones/*.md | 005 |
-| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 010 |
+| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 011 |
 
 ## Languages
 
diff --git a/docs/sqa/reviews/rc-010-code-mil-003.md b/docs/sqa/reviews/rc-010-code-mil-003.md
new file mode 100644
index 0000000..6e26b3c
--- /dev/null
+++ b/docs/sqa/reviews/rc-010-code-mil-003.md
@@ -0,0 +1,62 @@
+# RC-010 Code review of MIL-003
+
+## Metadata
+| Key | Value |
+| --- | --- |
+| ID | RC-010 |
+| CrossReference | [MIL-003], [QC-PY-001] |
+
+## Version History
+| Date | Status | Author | Reviewer | Change | Commit |
+| --- | --- | --- | --- | --- | --- |
+| 2026-11-06 | Accepted | Jens Tirsvad Nielsen | AI as stand-in for S01 | Initial version | [cc95105] |
+
+---
+
+## Artifact Under Review
+
+- Instance reviewed: [MIL-003]
+- Checklist used: [QC-PY-001]
+- Scope: Code of MIL-003: domain, application, infrastructure and presentation/web packages, `server.py`, and the unit and integration tests; written by the python-developer agent
+- Language and domain: n/a (technical type)
+- Language reviewer: none
+- Mode: autonomous, not independent (the reviewer is `AI as stand-in for S01`)
+
+## Checklist Results
+
+| # | Criterion | Status | Evidence/Notes |
+| --- | --- | --- | --- |
+| 1 | Packages, modules, functions, variables, classes and constants follow PEP 8 casing (`snake_case`, `PascalCase`, `UPPER_SNAKE`) | Pass | Modules and functions use snake_case, classes PascalCase, constants UPPER_SNAKE |
+| 2 | Names state purpose in the domain's language; no unexplained abbreviations, no single-letter names outside tiny scopes | Pass | Names state purpose (`compare_guess`, `GuessResult`, `HOME_HEADING`); no unexplained abbreviations |
+| 3 | Code is produced by the project's formatter and passes its linter with no unexplained suppressions | Pass | `ruff check` and `ruff format --check` report no finding; no suppressions |
+| 4 | Every function and method signature is type-annotated, including `-> None` | Pass | Every signature is annotated; `mypy --strict` reports no issue |
+| 5 | No bare `except:`, no swallowed exceptions; specific exceptions are raised and the cause is kept (`raise ... from`) | Pass | No bare `except`; no exception is swallowed |
+| 6 | No mutable default arguments and no shadowed builtins | Pass | No mutable default arguments; no builtin is shadowed |
+| 7 | Files, locks and connections are managed with context managers | N-A | No file, lock or connection is opened |
+| 8 | Public modules, classes and functions have docstrings that say what, not how | Pass | Public modules, classes and functions have Doxygen-style docstrings |
+| 9 | Logging uses `logging`, not `print`; no secrets or personal data in log output | Pass | No `print`; no secret in the code; `.env` is neither read nor imported |
+| 10 | Classes and operations trace to the Design Class Diagram they implement; deviations are recorded | N-A | No DCD exists (plain technical tasks) |
+| 11 | Tests exist for new behaviour, are named for the behaviour, and do not depend on order or the network | Pass | pytest tests are named for behaviour, run in any order and use no network |
+| 12 | Type checker runs in strict mode without errors; `Any` is justified in a comment | Pass | `mypy --strict` passes; no `Any` |
+| 13 | Dependencies are declared and pinned in the project's dependency file, none unused | Pass | `pyproject.toml` declares Flask (runtime) and pytest, ruff, mypy (extras); none unused |
+| 14 | Each piece of knowledge (a business rule, constant, format, validation or query) is defined in one place; code is merged only where it expresses the same knowledge, not where it merely looks alike | Pass | The comparison rule is only in `domain/rules.py`; headings, colours and GIFs only in `constants.py` |
+| 15 | Imports point inward: business-rule modules import no framework, database, UI or delivery-mechanism code, and there are no import cycles | Pass | domain imports only the standard library; application imports domain and constants; infrastructure imports only the standard library; presentation imports application, infrastructure and Flask; no cycle |
+| 16 | SOLID holds: a class or module has one reason to change; new behaviour is added by extension, not by editing a type test in several places; subclasses honour the contract of their base; protocols are narrow; high-level code depends on protocols or abstract types and receives its implementations | Pass | Each module has one reason to change; behaviour is added by extension |
+| 17 | Source is laid out in the layers and folders of the clean architecture folder structure (`domain`, `application`, `infrastructure`, `presentation` packages under `src/`, and `unit`, `integration` and `e2e` under `tests/`), in `snake_case`, and imports between the layers point inward | Pass | Domain rule, application use case, infrastructure random source and presentation web app sit in their layer packages; tests in `tests/unit` and `tests/integration` |
+| 18 | File and folder names are English, contain no space and no character outside letters, digits, `-`, `_` and `.`, and follow the casing of the language for files | Pass | File and folder names are English with letters, digits and `_` only |
+
+## Overall Verdict
+
+Go — All criteria pass or are not applicable; no blocking finding.
+
+## Action Items
+
+| Action | Owner | Due |
+| --- | --- | --- |
+| None | S01 | 2026-11-06 |
+
+---
+
+[MIL-003]: ../../docs/milestones/mil-003-higher-lower-game.md
+[QC-PY-001]: ../../framework/qc/code/qc-programming-python.md
+[cc95105]: https://git.tirsystem.com/Tirsvad-Udemy-100-days-of-code/055-higher-lower/commit/cc95105cf4fb9915e4c392fa58eec5d9a1f7c454
diff --git a/server.py b/server.py
new file mode 100644
index 0000000..2cdf7b9
--- /dev/null
+++ b/server.py
@@ -0,0 +1,12 @@
+"""Entry point of the Higher or Lower URLs project.
+
+@brief Composition root: builds the web application and runs it.
+"""
+
+from higher_lower.constants import HOST, PORT
+from higher_lower.presentation.web.app import create_app
+
+app = create_app()
+
+if __name__ == "__main__":
+    app.run(host=HOST, port=PORT)
diff --git a/src/higher_lower/application/guess_game.py b/src/higher_lower/application/guess_game.py
new file mode 100644
index 0000000..bf81caf
--- /dev/null
+++ b/src/higher_lower/application/guess_game.py
@@ -0,0 +1,34 @@
+"""Use case of the Higher or Lower game.
+
+@brief Holds the secret number and judges guesses against it.
+"""
+
+from higher_lower.constants import MAX_NUMBER, MIN_NUMBER
+from higher_lower.domain.rules import GuessResult, compare_guess
+
+
+class GuessGame:
+    """@brief One game with a fixed secret number."""
+
+    def __init__(self, secret_number: int) -> None:
+        """Start a game.
+
+        @param secret_number The number the player has to find.
+        """
+        self._secret_number = secret_number
+
+    def check(self, guess: int) -> GuessResult:
+        """Judge a guess.
+
+        @param guess The number the player guessed.
+        @return Whether the guess is low, high or correct.
+        """
+        return compare_guess(guess, self._secret_number)
+
+    def is_in_range(self, guess: int) -> bool:
+        """Tell whether a guess is inside the allowed range.
+
+        @param guess The number the player guessed.
+        @return True when the guess is between the minimum and maximum number.
+        """
+        return MIN_NUMBER <= guess <= MAX_NUMBER
diff --git a/src/higher_lower/domain/rules.py b/src/higher_lower/domain/rules.py
new file mode 100644
index 0000000..c84cc9e
--- /dev/null
+++ b/src/higher_lower/domain/rules.py
@@ -0,0 +1,28 @@
+"""Rules of the Higher or Lower game.
+
+@brief Pure comparison of a guess with the secret number.
+"""
+
+from enum import Enum
+
+
+class GuessResult(Enum):
+    """@brief Outcome of comparing a guess with the secret number."""
+
+    LOW = "low"
+    HIGH = "high"
+    CORRECT = "correct"
+
+
+def compare_guess(guess: int, secret: int) -> GuessResult:
+    """Compare a guess with the secret number.
+
+    @param guess The number the player guessed.
+    @param secret The number to find.
+    @return LOW if the guess is below the secret, HIGH if above, else CORRECT.
+    """
+    if guess < secret:
+        return GuessResult.LOW
+    if guess > secret:
+        return GuessResult.HIGH
+    return GuessResult.CORRECT
diff --git a/src/higher_lower/infrastructure/secret_number.py b/src/higher_lower/infrastructure/secret_number.py
new file mode 100644
index 0000000..e13a897
--- /dev/null
+++ b/src/higher_lower/infrastructure/secret_number.py
@@ -0,0 +1,16 @@
+"""Source of the secret number.
+
+@brief The only place in the project that uses randomness.
+"""
+
+import random
+
+
+def random_secret_number(minimum: int, maximum: int) -> int:
+    """Draw a secret number.
+
+    @param minimum Lowest possible number.
+    @param maximum Highest possible number.
+    @return A random integer from minimum to maximum, both included.
+    """
+    return random.randint(minimum, maximum)
diff --git a/src/higher_lower/presentation/web/__init__.py b/src/higher_lower/presentation/web/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/higher_lower/presentation/web/app.py b/src/higher_lower/presentation/web/app.py
new file mode 100644
index 0000000..97ce347
--- /dev/null
+++ b/src/higher_lower/presentation/web/app.py
@@ -0,0 +1,68 @@
+"""Flask application of the Higher or Lower game.
+
+@brief Routes that map a URL path to a guess and show the matching page.
+"""
+
+from flask import Blueprint, Flask, current_app
+
+from higher_lower.application.guess_game import GuessGame
+from higher_lower.constants import MAX_NUMBER, MIN_NUMBER
+from higher_lower.infrastructure.secret_number import random_secret_number
+from higher_lower.presentation.web.page import (
+    HOME_PAGE,
+    OUT_OF_RANGE_PAGE,
+    page_for_result,
+)
+from higher_lower.presentation.web.view import render_page
+
+## Key under which the game is stored in the Flask extensions registry.
+_GAME_KEY = "guess_game"
+
+## Blueprint that holds the views of the game.
+_blueprint = Blueprint("higher_lower", __name__)
+
+
+def _current_game() -> GuessGame:
+    """Find the game stored in the running application.
+
+    @return The game created by create_app.
+    """
+    game: GuessGame = current_app.extensions[_GAME_KEY]
+    return game
+
+
+@_blueprint.route("/")
+def home() -> str:
+    """Show the home page.
+
+    @return The home page HTML.
+    """
+    return render_page(HOME_PAGE)
+
+
+@_blueprint.route("/<int:guess>")
+def guess_number(guess: int) -> str:
+    """Judge the guess in the URL path.
+
+    @param guess The number the player guessed.
+    @return The page for a low, high, correct or out of range guess.
+    """
+    game = _current_game()
+    if not game.is_in_range(guess):
+        return render_page(OUT_OF_RANGE_PAGE)
+    return render_page(page_for_result(game.check(guess)))
+
+
+def create_app(secret_number: int | None = None) -> Flask:
+    """Build the Flask application.
+
+    @param secret_number The number to find; None draws a random one that
+        stays the same for the lifetime of the application.
+    @return The configured Flask application.
+    """
+    if secret_number is None:
+        secret_number = random_secret_number(MIN_NUMBER, MAX_NUMBER)
+    app = Flask(__name__)
+    app.extensions[_GAME_KEY] = GuessGame(secret_number)
+    app.register_blueprint(_blueprint)
+    return app
diff --git a/src/higher_lower/presentation/web/page.py b/src/higher_lower/presentation/web/page.py
new file mode 100644
index 0000000..4e3e21b
--- /dev/null
+++ b/src/higher_lower/presentation/web/page.py
@@ -0,0 +1,52 @@
+"""Page view model of the web presentation.
+
+@brief Plain data for one page, built from a guess result.
+"""
+
+from dataclasses import dataclass
+
+from higher_lower.constants import (
+    CORRECT_COLOUR,
+    CORRECT_GIF,
+    CORRECT_HEADING,
+    HIGH_COLOUR,
+    HIGH_GIF,
+    HIGH_HEADING,
+    HOME_COLOUR,
+    HOME_GIF,
+    HOME_HEADING,
+    LOW_COLOUR,
+    LOW_GIF,
+    LOW_HEADING,
+    OUT_OF_RANGE_COLOUR,
+    OUT_OF_RANGE_HEADING,
+)
+from higher_lower.domain.rules import GuessResult
+
+
+@dataclass(frozen=True, slots=True)
+class PageViewModel:
+    """@brief What a page shows: a coloured heading and a picture."""
+
+    heading: str
+    colour: str
+    gif: str
+
+
+HOME_PAGE = PageViewModel(HOME_HEADING, HOME_COLOUR, HOME_GIF)
+OUT_OF_RANGE_PAGE = PageViewModel(OUT_OF_RANGE_HEADING, OUT_OF_RANGE_COLOUR, HOME_GIF)
+
+_PAGES_BY_RESULT: dict[GuessResult, PageViewModel] = {
+    GuessResult.LOW: PageViewModel(LOW_HEADING, LOW_COLOUR, LOW_GIF),
+    GuessResult.HIGH: PageViewModel(HIGH_HEADING, HIGH_COLOUR, HIGH_GIF),
+    GuessResult.CORRECT: PageViewModel(CORRECT_HEADING, CORRECT_COLOUR, CORRECT_GIF),
+}
+
+
+def page_for_result(result: GuessResult) -> PageViewModel:
+    """Build the page that tells the player how the guess went.
+
+    @param result The outcome of the guess.
+    @return The page view model for that outcome.
+    """
+    return _PAGES_BY_RESULT[result]
diff --git a/src/higher_lower/presentation/web/view.py b/src/higher_lower/presentation/web/view.py
new file mode 100644
index 0000000..b79e856
--- /dev/null
+++ b/src/higher_lower/presentation/web/view.py
@@ -0,0 +1,20 @@
+"""HTML view of the web presentation.
+
+@brief Renders a page view model as HTML.
+"""
+
+from html import escape
+
+from higher_lower.presentation.web.page import PageViewModel
+
+
+def render_page(page: PageViewModel) -> str:
+    """Render a page as HTML, escaping every value.
+
+    @param page The page to show.
+    @return A heading in the page colour followed by the picture.
+    """
+    colour = escape(page.colour)
+    heading = escape(page.heading)
+    gif = escape(page.gif)
+    return f'<h1 style="color: {colour}">{heading}</h1><img src="{gif}">'
diff --git a/tests/integration/test_web_app.py b/tests/integration/test_web_app.py
new file mode 100644
index 0000000..518ee1e
--- /dev/null
+++ b/tests/integration/test_web_app.py
@@ -0,0 +1,89 @@
+"""Tests of the web application through the Flask test client."""
+
+import pytest
+from flask.testing import FlaskClient
+
+from higher_lower import constants
+from higher_lower.presentation.web.app import create_app
+
+SECRET = 5
+
+
+@pytest.fixture
+def client() -> FlaskClient:
+    return create_app(SECRET).test_client()
+
+
+def _body(client: FlaskClient, path: str) -> str:
+    return client.get(path).get_data(as_text=True)
+
+
+def _expected(heading: str, colour: str, gif: str) -> str:
+    return f'<h1 style="color: {colour}">{heading}</h1><img src="{gif}">'
+
+
+def test_home_page_shows_home_heading_colour_and_gif(client: FlaskClient) -> None:
+    expected = _expected(
+        constants.HOME_HEADING, constants.HOME_COLOUR, constants.HOME_GIF
+    )
+    assert _body(client, "/") == expected
+
+
+def test_guess_below_secret_shows_too_low_page(client: FlaskClient) -> None:
+    expected = _expected(constants.LOW_HEADING, constants.LOW_COLOUR, constants.LOW_GIF)
+    assert _body(client, "/3") == expected
+
+
+def test_guess_above_secret_shows_too_high_page(client: FlaskClient) -> None:
+    expected = _expected(
+        constants.HIGH_HEADING, constants.HIGH_COLOUR, constants.HIGH_GIF
+    )
+    assert _body(client, "/7") == expected
+
+
+def test_guess_equal_to_secret_shows_correct_page(client: FlaskClient) -> None:
+    expected = _expected(
+        constants.CORRECT_HEADING, constants.CORRECT_COLOUR, constants.CORRECT_GIF
+    )
+    assert _body(client, "/5") == expected
+
+
+def test_pages_use_distinct_colours() -> None:
+    colours = {
+        constants.HOME_COLOUR,
+        constants.LOW_COLOUR,
+        constants.HIGH_COLOUR,
+        constants.CORRECT_COLOUR,
+        constants.OUT_OF_RANGE_COLOUR,
+    }
+    assert len(colours) == 5
+
+
+def test_guess_above_range_shows_out_of_range_page_with_home_gif(
+    client: FlaskClient,
+) -> None:
+    response = client.get("/10")
+    expected = _expected(
+        constants.OUT_OF_RANGE_HEADING,
+        constants.OUT_OF_RANGE_COLOUR,
+        constants.HOME_GIF,
+    )
+    assert response.status_code == 200
+    assert response.get_data(as_text=True) == expected
+
+
+@pytest.mark.parametrize("path", ["/-1", "/abc"])
+def test_negative_or_text_path_is_not_found(client: FlaskClient, path: str) -> None:
+    assert client.get(path).status_code == 404
+
+
+def test_app_without_secret_keeps_one_random_secret() -> None:
+    client = create_app().test_client()
+    numbers = range(constants.MIN_NUMBER, constants.MAX_NUMBER + 1)
+    first = [_body(client, f"/{n}") for n in numbers]
+    second = [_body(client, f"/{n}") for n in numbers]
+    correct = _expected(
+        constants.CORRECT_HEADING, constants.CORRECT_COLOUR, constants.CORRECT_GIF
+    )
+    assert first == second
+    assert first.count(correct) == 1
diff --git a/tests/unit/test_guess_game.py b/tests/unit/test_guess_game.py
new file mode 100644
index 0000000..1bdb99d
--- /dev/null
+++ b/tests/unit/test_guess_game.py
@@ -0,0 +1,24 @@
+"""Tests of the guess game use case."""
+
+import pytest
+
+from higher_lower.application.guess_game import GuessGame
+from higher_lower.constants import MAX_NUMBER, MIN_NUMBER
+from higher_lower.domain.rules import GuessResult
+
+
+def test_check_reports_low_high_and_correct() -> None:
+    game = GuessGame(5)
+    assert game.check(2) is GuessResult.LOW
+    assert game.check(8) is GuessResult.HIGH
+    assert game.check(5) is GuessResult.CORRECT
+
+
+@pytest.mark.parametrize("guess", [MIN_NUMBER, MAX_NUMBER])
+def test_is_in_range_accepts_limits(guess: int) -> None:
+    assert GuessGame(5).is_in_range(guess)
+
+
+@pytest.mark.parametrize("guess", [MIN_NUMBER - 1, MAX_NUMBER + 1])
+def test_is_in_range_rejects_values_just_outside(guess: int) -> None:
+    assert not GuessGame(5).is_in_range(guess)
diff --git a/tests/unit/test_rules.py b/tests/unit/test_rules.py
new file mode 100644
index 0000000..a0b7d6c
--- /dev/null
+++ b/tests/unit/test_rules.py
@@ -0,0 +1,17 @@
+"""Tests of the game rules."""
+
+import pytest
+
+from higher_lower.domain.rules import GuessResult, compare_guess
+
+
+@pytest.mark.parametrize(
+    ("guess", "expected"),
+    [(3, GuessResult.LOW), (7, GuessResult.HIGH), (5, GuessResult.CORRECT)],
+)
+def test_compare_guess_classifies_guess(guess: int, expected: GuessResult) -> None:
+    assert compare_guess(guess, 5) is expected
+
+
+def test_compare_guess_is_correct_at_lower_boundary() -> None:
+    assert compare_guess(0, 0) is GuessResult.CORRECT
diff --git a/tests/unit/test_secret_number.py b/tests/unit/test_secret_number.py
new file mode 100644
index 0000000..72e3d01
--- /dev/null
+++ b/tests/unit/test_secret_number.py
@@ -0,0 +1,14 @@
+"""Tests of the secret number source."""
+
+from higher_lower.infrastructure.secret_number import random_secret_number
+
+DRAWS = 500
+
+
+def test_random_secret_number_stays_in_range() -> None:
+    draws = [random_secret_number(0, 9) for _ in range(DRAWS)]
+    assert all(0 <= value <= 9 for value in draws)
+
+
+def test_random_secret_number_returns_the_only_possible_value() -> None:
+    assert random_secret_number(4, 4) == 4