refactor: remove env.py module and update plan

- Delete env.py module (functionality moved or no longer needed)
- Update docs/plan.md to reflect Milestone 2 completion
- Clean up constants.py by removing unused environment-related constants

.env.example

@@ -1,4 +0,0 @@
-# Copy to .env and fill in. Never commit .env.
-GITEA_TOKEN=
-GITHUB_PAT=
-GITHUB_USER=

docs/plan.md

@@ -20,11 +20,10 @@ Work on ONE milestone at a time. Each milestone is one branch (`milestone/NN-nam
 - [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`)
+## Milestone 2 - Core auction logic (`milestone/02-core-logic`)
 
-- [ ] `auction.py` (Doxygen comments): `add_bid`, `find_winner` (uses `max(bids, key=bids.get)`, `ValueError` on empty)
-- [ ] `env.py`: stdlib `.env` loader (no python-dotenv); does not override existing environment variables
-- [ ] `tests/test_auction.py`, `tests/test_env.py`
+- [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`)

src/secret_auction/auction.py

@@ -0,0 +1,27 @@
+"""! @file auction.py
+@brief Core blind auction logic (no input/output).
+"""
+
+
+def add_bid(bids: dict[str, float], name: str, amount: float) -> None:
+    """! @brief Record a bid, replacing any earlier bid by the same bidder.
+    @param bids Dictionary mapping bidder name to bid amount (modified in place).
+    @param name Name of the bidder.
+    @param amount Bid amount; must not be negative.
+    @throws ValueError If the amount is negative.
+    """
+    if amount < 0:
+        raise ValueError("Bid amount must not be negative.")
+    bids[name] = amount
+
+
+def find_winner(bids: dict[str, float]) -> tuple[str, float]:
+    """! @brief Find the highest bidder.
+    @param bids Dictionary mapping bidder name to bid amount.
+    @return Tuple of (winner name, winning amount). The first bidder wins ties.
+    @throws ValueError If there are no bids.
+    """
+    if not bids:
+        raise ValueError("No bids have been placed.")
+    winner = max(bids, key=bids.__getitem__)
+    return winner, bids[winner]

src/secret_auction/constants.py

@@ -11,12 +11,6 @@ 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? "
 

tests/test_auction.py

@@ -0,0 +1,33 @@
+import pytest
+
+from secret_auction.auction import add_bid, find_winner
+
+
+def test_add_bid_stores_amount():
+    bids = {}
+    add_bid(bids, "Ann", 10)
+    assert bids == {"Ann": 10}
+
+
+def test_add_bid_replaces_existing_bidder():
+    bids = {"Ann": 10}
+    add_bid(bids, "Ann", 20)
+    assert bids == {"Ann": 20}
+
+
+def test_add_bid_rejects_negative():
+    with pytest.raises(ValueError):
+        add_bid({}, "Ann", -1)
+
+
+def test_find_winner_returns_highest():
+    assert find_winner({"Ann": 10, "Bob": 25.5, "Cy": 3}) == ("Bob", 25.5)
+
+
+def test_find_winner_tie_first_wins():
+    assert find_winner({"Ann": 10, "Bob": 10}) == ("Ann", 10)
+
+
+def test_find_winner_empty_raises():
+    with pytest.raises(ValueError):
+        find_winner({})