diff --git a/docs/plan.md b/docs/plan.md
index 9b4156d..8b682b7 100644
--- a/docs/plan.md
+++ b/docs/plan.md
@@ -1,41 +1,40 @@
-# Plan: Secret Auction Program (Day 9)
-
-## Context
-
-Udemy 100 Days of Code blind-auction CLI. The repository uses a Python `.gitignore`, an AGPL `LICENSE` and a git-ignored `.env` (tokens, never printed or committed). Python 3.13 or newer is required.
-
-## Working method
-
-Work on ONE milestone at a time. Each milestone is one branch (`milestone/NN-name`) and one pull request. When a milestone is finished, stop, verify it and review before starting the next. Milestones and issues are also tracked on the Gitea repository (via API, token from `.env`).
-
-## Milestone 1 - Project scaffold and repo metadata (`milestone/01-scaffold`)
-
-- [x] Create `src/secret_auction/__init__.py`, `tests/`, `docs/`
-- [x] `pyproject.toml`: `requires-python >=3.13`, src layout, no runtime deps, `dev` extra (`pytest`), pytest config, console script
-- [x] `.env.example`; `.env` and `.venv/` ignored; add `docs/doxygen/` to `.gitignore`
-- [x] `constants.py`
-- [x] `Doxyfile`
-- [x] Set repository description and topics (`python`, `udemy`, `100-days-of-code`, `blind-auction`, `beginner`) via API
-- [x] Create milestones and issues on the host (milestones M1-M4, issues #1-#12)
-- [x] Verify: create `.venv`, upgrade pip, `pip install -e ".[dev]"`
-- [x] Save plan and milestones in `docs/plan.md`
-
-## Milestone 2 - Core auction logic and env loader (`milestone/02-core-logic`)
-
-- [x] `auction.py` (Doxygen comments): `add_bid`, `find_winner` (uses `max(bids, key=bids.get)`, `ValueError` on empty)
-- [x] `env.py`: stdlib `.env` loader (no python-dotenv); does not override existing environment variables
-- [x] `tests/test_auction.py` (`.env` loader is for private use and intentionally not tested)
-- Verify: `pytest` passes
-
-## Milestone 3 - CLI program (`milestone/03-cli`)
-
-- [ ] `main.py`: prompt name and numeric bid (re-prompt on invalid), bids dict kept outside the loop, "other bidders? yes/no", clear screen with newlines between bidders, announce the winner
-- [ ] `tests/test_main.py` with monkeypatched `input`
-- Verify: `pytest`; scripted run `python -m secret_auction.main` with two bidders
-
-## Milestone 4 - Documentation (`milestone/04-docs`)
-
-- [ ] `README.md` from the template (Overview, Requirements, Setup incl. creating/activating `.venv` and `python -m pip install --upgrade pip`, Run, Tests, License AGPL, Links)
-- [ ] `docs/flowchart.md` (Mermaid plus link to the diagrams.net chart)
-- [ ] Generate Doxygen docs if `doxygen` is installed
-- Verify: README commands work verbatim; `.env` stays untracked
+# Plan: Secret Auction Program (Day 9)
+
+## Context
+
+Udemy 100 Days of Code blind-auction CLI. The repository uses a Python `.gitignore`, an AGPL `LICENSE` and a git-ignored `.env` (tokens, never printed or committed). Python 3.13 or newer is required.
+
+## Working method
+
+Work on ONE milestone at a time. Each milestone is one branch (`milestone/NN-name`) and one pull request. When a milestone is finished, stop, verify it and review before starting the next. Milestones and issues are also tracked on the Gitea repository (via API, token from `.env`).
+
+## Milestone 1 - Project scaffold and repo metadata (`milestone/01-scaffold`)
+
+- [x] Create `src/secret_auction/__init__.py`, `tests/`, `docs/`
+- [x] `pyproject.toml`: `requires-python >=3.13`, src layout, no runtime deps, `dev` extra (`pytest`), pytest config, console script
+- [x] `.env.example`; `.env` and `.venv/` ignored; add `docs/doxygen/` to `.gitignore`
+- [x] `constants.py`
+- [x] `Doxyfile`
+- [x] Set repository description and topics (`python`, `udemy`, `100-days-of-code`, `blind-auction`, `beginner`) via API
+- [x] Create milestones and issues on the host (milestones M1-M4, issues #1-#12)
+- [x] Verify: create `.venv`, upgrade pip, `pip install -e ".[dev]"`
+- [x] Save plan and milestones in `docs/plan.md`
+
+## Milestone 2 - Core auction logic (`milestone/02-core-logic`)
+
+- [x] `auction.py` (Doxygen comments): `add_bid`, `find_winner` (uses `max(bids, key=bids.get)`, `ValueError` on empty)
+- [x] `tests/test_auction.py`
+- Verify: `pytest` passes
+
+## Milestone 3 - CLI program (`milestone/03-cli`)
+
+- [ ] `main.py`: prompt name and numeric bid (re-prompt on invalid), bids dict kept outside the loop, "other bidders? yes/no", clear screen with newlines between bidders, announce the winner
+- [ ] `tests/test_main.py` with monkeypatched `input`
+- Verify: `pytest`; scripted run `python -m secret_auction.main` with two bidders
+
+## Milestone 4 - Documentation (`milestone/04-docs`)
+
+- [ ] `README.md` from the template (Overview, Requirements, Setup incl. creating/activating `.venv` and `python -m pip install --upgrade pip`, Run, Tests, License AGPL, Links)
+- [ ] `docs/flowchart.md` (Mermaid plus link to the diagrams.net chart)
+- [ ] Generate Doxygen docs if `doxygen` is installed
+- Verify: README commands work verbatim; `.env` stays untracked
diff --git a/src/secret_auction/constants.py b/src/secret_auction/constants.py
index f199f24..437357a 100644
--- a/src/secret_auction/constants.py
+++ b/src/secret_auction/constants.py
@@ -1,39 +1,33 @@
-"""! @file constants.py
-@brief Constants used by the Secret Auction program.
-"""
-
-## Number of blank lines printed to hide previous bidders' entries.
-CLEAR_SCREEN_LINES = 100
-
-## Answers accepted as "yes" when asking for more bidders.
-YES_ANSWERS = ("yes", "y")
-
-## Answers accepted as "no" when asking for more bidders.
-NO_ANSWERS = ("no", "n")
-
-## Path of the file holding environment variables (tokens).
-ENV_FILE = ".env"
-
-## Name of the environment variable holding the Gitea token.
-GITEA_TOKEN_ENV_VAR = "GITEA_TOKEN"
-
-## Prompt asking for the bidder's name.
-PROMPT_NAME = "What is your name? "
-
-## Prompt asking for the bid amount.
-PROMPT_BID = "What is your bid? $"
-
-## Prompt asking whether more bidders exist.
-PROMPT_MORE_BIDDERS = "Are there any other bidders? Type 'yes' or 'no'. "
-
-## Message shown when the bid is not a valid number.
-MSG_INVALID_BID = "Please enter a valid, non-negative number."
-
-## Message shown when the yes/no answer is not understood.
-MSG_INVALID_ANSWER = "Please type 'yes' or 'no'."
-
-## Template for the winner announcement.
-MSG_WINNER = "The winner is {name} with a bid of ${amount:.2f}."
-
-## Welcome banner.
-MSG_WELCOME = "Welcome to the secret auction program."
+"""! @file constants.py
+@brief Constants used by the Secret Auction program.
+"""
+
+## Number of blank lines printed to hide previous bidders' entries.
+CLEAR_SCREEN_LINES = 100
+
+## Answers accepted as "yes" when asking for more bidders.
+YES_ANSWERS = ("yes", "y")
+
+## Answers accepted as "no" when asking for more bidders.
+NO_ANSWERS = ("no", "n")
+
+## Prompt asking for the bidder's name.
+PROMPT_NAME = "What is your name? "
+
+## Prompt asking for the bid amount.
+PROMPT_BID = "What is your bid? $"
+
+## Prompt asking whether more bidders exist.
+PROMPT_MORE_BIDDERS = "Are there any other bidders? Type 'yes' or 'no'. "
+
+## Message shown when the bid is not a valid number.
+MSG_INVALID_BID = "Please enter a valid, non-negative number."
+
+## Message shown when the yes/no answer is not understood.
+MSG_INVALID_ANSWER = "Please type 'yes' or 'no'."
+
+## Template for the winner announcement.
+MSG_WINNER = "The winner is {name} with a bid of ${amount:.2f}."
+
+## Welcome banner.
+MSG_WELCOME = "Welcome to the secret auction program."
diff --git a/src/secret_auction/env.py b/src/secret_auction/env.py
deleted file mode 100644
index e88c935..0000000
--- a/src/secret_auction/env.py
+++ /dev/null
@@ -1,38 +0,0 @@
-"""! @file env.py
-@brief Minimal `.env` file loader using only the standard library.
-"""
-
-import os
-from pathlib import Path
-
-
-def parse_env(text: str) -> dict[str, str]:
-    """! @brief Parse `KEY=VALUE` lines.
-    @param text Contents of a `.env` file. Blank lines and `#` comments are ignored.
-    @return Dictionary of parsed variables; surrounding quotes are stripped.
-    """
-    values: dict[str, str] = {}
-    for line in text.splitlines():
-        line = line.strip()
-        if not line or line.startswith("#") or "=" not in line:
-            continue
-        key, value = line.split("=", 1)
-        value = value.strip()
-        if len(value) >= 2 and value[0] == value[-1] and value[0] in "\"'":
-            value = value[1:-1]
-        values[key.strip()] = value
-    return values
-
-
-def load_env(path: str | Path) -> dict[str, str]:
-    """! @brief Load a `.env` file into `os.environ` without overriding existing variables.
-    @param path Path to the `.env` file; a missing file is not an error.
-    @return Dictionary of the variables read from the file.
-    """
-    file = Path(path)
-    if not file.is_file():
-        return {}
-    values = parse_env(file.read_text(encoding="utf-8"))
-    for key, value in values.items():
-        os.environ.setdefault(key, value)
-    return values