Lighthouse: Text Adventure Engine

Lighthouse: Text Adventure Engine

You've joined the small team behind Lighthouse, a text adventure that ships inside a mobile reading app. The engine parses what the player types, runs it against a five-room world, and replies with a line of text. Players have filed two bugs, and the mobile team needs a carry limit and save games before the next release.

Codebase

• adventure/config.py: start room, carry limit, verb synonyms, direction words, exit order.
• adventure/world.py: static rooms, exits, items (with weights) and the locked trapdoor. Known-good data.
• adventure/parser.py: turns raw input into a Command(verb, noun).
• adventure/state.py: GameState (current room, inventory, items per room, flags) and find_item.
• adventure/commands.py: one handler per verb. Each returns the reply text.
• adventure/engine.py: Game, which parses input and routes it to a handler.
• adventure/persistence.py: save/load stubs (Part 3).
• adventure/api.py: the run(operations) entrypoint.
• tests/: existing unit tests. test_case_insensitive and test_take_twice fail today.

How your code is run

run(operations: list[list]) -> list starts one new game and returns exactly one output per operation.

Input rules. Commands are case-insensitive. Extra spaces are ignored, and the words the, a, an are dropped wherever they appear. The noun is whatever is left after the verb, in lowercase, single-spaced. An item is referred to by its name or one of its aliases (world.py).

Replies (<name> is the item's name from world.py, <noun> is the noun as normalized):

Worked example

[["cmd", "look"], ["cmd", "go north"], ["cmd", "get the lamp"], ["cmd", "examine lantern"]]

returns

["Beach. Waves fold over grey sand. Items: shell, driftwood. Exits: north.",
 "Cliff Path. A narrow path climbs the cliff. Items: lantern, rope. Exits: north, south.",
 "Taken: lantern.",
 "A storm lantern with a little oil left."]

Part 1: Player bug reports

Goal: fix both reports.

1. "Typing TAKE Lantern says *I don't understand that.*" Every rule above must work regardless of letter case, for verbs, directions, articles and item names. Replies that echo <noun> use the lowercase form (take ROPE on the beach replies There is no rope here.).
2. "Taking something I already have gives me a second copy." take <item> for an item you are already carrying must reply You already have the <name>. and change nothing. This check comes before the fixed-in-place check.

Part 2: Carry limit

Goal: enforce config.MAX_CARRY_WEIGHT (10) using the item weights in world.py.

1. You may hold items whose weights add up to at most 10 (exactly 10 is allowed).
2. take <item> that would go over the limit replies The <name> is too heavy. and changes nothing. Check order for take <item>: missing noun, not found, already carried, fixed in place, too heavy.
3. take all goes through the room's items in order, taking each one that still fits and skipping fixed items. The reply is Taken: <names>. if anything was taken, followed by (after one space) Too heavy: <names>. if anything didn't fit. If neither applies: There is nothing to take.
4. inventory now ends with the carried weight: You are carrying: lantern, rope (5/10). and You are carrying nothing (0/10).

Example (in the Lighthouse, carrying nothing): take all replies Taken: brass key, logbook. Too heavy: anvil.

Part 3: Save and load

Goal: implement persistence.to_save and persistence.from_save so save and load work.

1. save returns a dict: {"version": 1, "room": <room id>, "inventory": [<item ids in pickup order>], "rooms": {<every room id>: [<item ids in room order>]}, "flags": {"trapdoor_unlocked": <bool>}}. Ids are the keys of ROOMS and ITEMS in world.py (for example "brass_key", "lamp_room").
2. A save is a snapshot: commands run after save must not change a dict it already returned.
3. load replaces the whole game with the save's state and returns "ok". Commands after it carry on from that state, and saving straight away returns an equal dict.
4. load validates in this order and returns the first error, leaving the current game untouched:
5. version is not 1 (or the save isn't a dict): "error: unsupported version"
6. room isn't a room id: "error: unknown room '<room>'"
7. inventory isn't a list, rooms doesn't have exactly the five room ids with a list for each, any id is unknown, any item appears zero or several times overall, or a fixed item is in the inventory: "error: corrupt save"
8. inventory weight is over the carry limit: "error: inventory too heavy"
9. Older saves (written before the trapdoor shipped) have no flags key. Treat a missing key, or a missing flag, as false.

Notes

• world.py and config.py are known-good. The bugs are in the code that uses them.
• Use the AI assistant freely, but check its changes against the reply table above.
• Later parts must not break earlier ones. Hidden tests re-check earlier behaviour.