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Solver options

Français · Reference · Published, reviewed by a person · Applies from: 4.1.13

Every option of solve, the solver's command, and of the tools around it: what it does, its default, and since when. What the answers mean (a winning path, a proof, truncated) is in What the solver proves.

Audience, context, and the statuses of what this page rests on

Audience: author · Context: engine repository, created project

Where to run it

• In the engine repository (a clone of quest-n-click): npm run solve -- <options>. The game is GAME=<id>, otherwise config.game of package.json (games/<id>/).
• In a created project (made by npx quest-n-click create): npx quest-n-click solve <options>. The game is game/. npm run verify runs validate, solve, i18n status, lint and playtests; npm run release adds solve --prove and solve-reality.

The tools marked engine repository below (prove:matrix, audit:corpus, bench, replay, page:*) have no quest-n-click subcommand: a created project does not have them.

# in the engine repository
npm run solve -- --prove --profile

# in a created project
npx quest-n-click solve --prove --profile

All the options at a glance

Option	What it does	Default	Since
(none)	A witness: one path from "New game" to the ending
--prove	Every reachable state; each one that lost the ending is a softlock	witness
--from=<checkpoint>	Start from a checkpoint of game.checkpoints instead of "New game"	"New game"
--chapters	One search per checkpoint that declares goals, then from the last one to the ending
--goal=100%	The goal is every objective that is not optional (GameDef.objectives), all at once, instead of the ending	the ending	4.1.12
--max=<n>	State budget	20000
--time=<s>	Time budget, in seconds	none	3.5
--mem=<MB>	Heap budget, in MB (Node only, read every 256 expansions)	none	4.1.13
--checkpoint=<file>	Write the search down as it goes	none	4.1.13
--checkpoint-every=<s>	How often, in seconds	300	4.1.13
--resume	Take the search up from --checkpoint's file		4.1.13
--workers=<n>|auto	Expand the frontier on worker threads	none (one thread)	3.5
--batch=<n>	Nodes taken from the frontier at once, with workers	64	3.5
--profile	What the search cost and what the states are made of
--json	One line of JSON on stdout, no other text
--no-cache	Do not read or write the proof cache	cache on
--por=sleep|stubborn	Partial-order reduction, witness only	off
--dominance	Witness dominance, witness only	off	3.5
--ownership=off	No canonical owner in a proof	on in a proof	3.5
--symmetry	Fold symmetric items in a proof	off	4.1.13
--representation=objects	The 4.1.8 storage of states	compact	4.1.13
--audit-abstractions	The proof with the abstractions against the explicit search		3.3.1

An unknown option is ignored: the command reads only the options it knows. --goal= with anything other than 100% is refused (exit 2).

--prove, --from, --chapters, --goal=100%

• npm run solve alone looks for one winning path and stops at the ending.
• --prove explores every reachable state and reports the softlocks, grouped by cause.
• --from=<checkpoint> starts from that checkpoint, for example --from=market: handy while you work on one room.
• --chapters runs one bounded search per checkpoint that declares goals: from the previous checkpoint (or "New game") until its goals hold, then from the last one to the ending. Each chapter must be solvable on its own. A game with no checkpoint declaring goals prints "no chapter to solve" and exits 0.
• --prove --chapters proves each chapter from every reachable boundary state of the previous one (deduplicated by what the chapter reads), not from the hand-written checkpoint, which must itself be one of those boundary states (checkpoint_mismatch otherwise). A chapter starts from at most 1 000 distinct boundary states; past that, it is truncated and the proof stops there.
• --goal=100% searches for a state where every objective that is not optional holds at once (4.1.12, ADR 0014). Exit 2 for a game that declares none. An objective whose done the content can take back may make it unreachable; the validator warns about it.

# in the engine repository
npm run solve -- --from=market --max=50000
npm run solve -- --chapters
npm run solve -- --prove --chapters
npm run solve -- --goal=100%

Long proofs: budgets, checkpoints, memory

--max (states, 20 000 by default), --time (seconds) and --mem (MB of heap) bound a search. Each one stops it as truncated, exit 2, with the budget that stopped it named in the sentence ("raise --max", "raise --time", "raise --mem, or resume from the checkpoint"). A truncated search is never a proof.

--checkpoint=<file> writes the search down every --checkpoint-every seconds (300 by default) and when a budget stops it: the store, the frontier in its order, the counters. --resume takes it up from that file, to the same verdict and the same witness as a search that never stopped (tests/checkpoint.test.ts kills a real process with SIGKILL at 30 % and resumes it). A snapshot belongs to one search: the game and the options that change what is found are its fingerprint, and another search ignores it (the profile says why). A finished search removes its file. The checkpoint covers the whole game's search; --chapters runs several searches and does not use it. It needs the compact representation.

# in the engine repository: a long proof, written down, then resumed with a bigger budget
npm run solve -- --prove --checkpoint=p.ckpt --checkpoint-every=300 --mem=3500
npm run solve -- --prove --checkpoint=p.ckpt --resume --max=200000

Guarantee · checkpoint-resume-same-proof · referenced · executed on 47dccf1b4b15 · scope reviewed A search cut by its budget is written down, and a bigger budget takes it up to the same proof as a search that never stopped.

Workers

--workers=N expands the frontier a batch at a time (--batch, 64 by default) on worker threads; auto takes the cores but one, at most 8. The merge stays in the batch's order, so the result depends on the batch, never on the number of workers (tests/workers.test.ts, tests/partition.test.ts). Since 4.1.13 the search shares its visited table with the workers (the 64-bit hash of every stored state): a worker sends a state the search has already stored back without its engine state. The exact keys stay the authority: a worker's "already stored" that the search does not confirm is expanded again in the search's thread. Each node goes first to the worker its room hashes to, and an idle worker steals from the longest queue. A worker that stops mid-search leaves the pool, with the same proof, and the profile says so.

Workers speed an exploration up; they do not answer an explosion of states. Measured in 3.5 (5 October 2026, Benchmarks): a large proof went about 2.5 times faster with 4 workers. They do not combine with a partial-order reduction.

# in the engine repository
npm run solve -- --prove --workers=4 --batch=64 --time=60

Reading the profile

npm run solve -- --profile (the Studio's Check tab, "Solver health"; the solve MCP tool with profile: true) says why a search is slow or big. With --prove, since 4.1.13, it also gives the explosion profile. Here is an excerpt on the demo game (engine repository, main, 23 October 2026):

SOLVER PROFILE
  states explored       3480
  engine runs           56588  (107244 tries changed nothing, 79588 of them not run: the no-op memo knew; 25455 landed on a known state)
  actions not run       713640  (no rule could answer them)
  actions per state     44.7 on average, 51 at most (market, 3 items in the bag: 1 Give, 2 Map, 3 Switch changed something)

Abstractions (what each one did, or why it is off):
  canonical character   3048 switches folded, 0 kept explicit
  mobility regions      off (no move of this game can be silent)
  witness dominance     off (off in proofs: it changes softlock verdicts on generated games (tests/dominance.test.ts))
  symmetric items       off (not asked for (--symmetry))
  representation        compact, 427 KB of tables

Explosion: what multiplies the 3480 states measured (states that would merge without it)
  positions        2904  (18 distinct values over 3 dimension(s))
  inventories      3042  (76 distinct values over 2 dimension(s))
  flags            3000  (78 distinct values over 13 dimension(s))
…
What splits the states (states that would merge without it):
    2940  pos biscuit  (44 values)
    2400  pos hero  (30 values)
…
Use / give combinations per room (over its expansions):
  house: 84096 candidates, 465 answered by a rule, 81021 could only fall back (96% useless)
Independent dimensions (their combinations multiply the states; a checkpoint between them would cut it):
  ⚠ nth house.take-teacup.nth, flag lou_has_key, prop house.armchair: 8 of 8 combinations seen
Monotonic (never lost once gained): 10 flags, 1 items (shell_phone)

How to read it:

• What splits the states. Each dimension of the state (an item in the bag, a flag, a prop state, a script position…) is scored by how many states would merge if it were dropped. The top of that list is what the game's logic is made of, or the puzzle that went combinatorial.
• Explosion. The stored states are attributed to five families: positions, inventories, flags and counters, what a dialogue writes, what a script or an event writes. For each, how many states would merge without it: what it multiplies. Three counts say what never became a state: symmetries folded, tries that changed nothing, and transitions that landed on a state already seen (two orders of independent actions).
• Abstractions. Each abstraction has a line: what it did, or why it is off.
• Independent dimensions. Groups of two-valued dimensions whose combinations all show up evolve independently: a checkpoint with goals between them makes each chapter's search small. The independent sub-puzzles are reported, not applied: proving each alone needs a product argument the search does not make.
• Use / give combinations. How many tries could only fall back to a default answer.

The heat map on the puzzle graph (Check tab) shows the same numbers on the rules and rooms; "why is this live?" on a card explains why the solver keeps a thing in its state. docs/dev/PROOF-PROFILE.md is this profile for each instance of the proof matrix.

--json and the output

Without --json, the output is for people and other scripts read it as is: the verdict line, the path found (or the path to the last state explored), the rooms reached, the map places unlocked, the flags set, the items obtained but never used, the items never obtained, up to five dead ends, up to ten softlock causes, the invariants broken and the engine errors.

--json prints one line of JSON and nothing else: status, exit, headline, mode, cached, finished, states, truncated, path (labelled for people), steps (the session entries npm run e2e replays), softlockCount, softlockCauses, roomsReached, unlockedReached, flagsReached, itemsNeverUsed, unusedItems, softlocks, assumptions, errors, broken, profile. With --prove --chapters: status, exit, headline, ms and chapters.

The proof cache: --no-cache, PROOF_CACHE, PROOF_CACHE_DIR

A solver run depends only on the engine's code, the game (content, layouts, custom commands, and the sources of the game folder) and the options. solve (every mode), --chapters and lint keep each result in .cache/proofs/ and give it back when none of that changed, saying so: (from the proof cache, key …), and cached in --json. The build, verify:game, prove:game and release-check ask the same questions several times; on the demo a warm proof took 0.17 s instead of 2.4 s cold when the cache arrived (3.3.0, CHANGELOG.md).

• --no-cache (on solve) or PROOF_CACHE=0 runs again without reading or writing it.
• PROOF_CACHE_DIR=<folder> moves it.
• An engine error is never kept. The 300 most recent results are kept; older ones go first.
• Tests call the solver directly and never use it.

--por, --dominance, --ownership=off, --symmetry, --representation=objects

• --por=sleep|stubborn: partial-order reduction, commuting actions tried one at a time (fewer engine runs with sleep, fewer states too with stubborn). It has no proof of equivalence for softlocks: with --prove it is ignored, and the command says so.
• --dominance: a witness skips a state with no more progress than one already seen. Witnesses only; a witness that finds nothing with it is run again without it.
• --ownership=off: no canonical owner (who holds an item no condition reads) in a proof.
• --symmetry: two items the game treats alike are folded in a proof. Off by default.
• --representation=objects: every state stored whole, as in 4.1.8: the reference the differential tests compare with. The default is compact (ADR 0015).

What each of these changes in a verdict is in What the solver proves.

--audit-abstractions and audit:corpus

# in the engine repository, or npx quest-n-click solve --audit-abstractions in a created project
npm run solve -- --audit-abstractions

The proof with the abstractions (every no-op memo hit run anyway and compared) against the explicit search (canonical character, mobility regions, canonical owner and memo off). Exit 0 same, 1 diverged, 2 the explicit search did not fit --max (the verdicts were not compared). npm run release-check runs it.

# in the engine repository only
npm run audit:corpus -- --seeds=500                              # every night in CI: exit 1 on a divergence
npm run audit:corpus -- --from=126 --seeds=125 --json=s.json     # one shard: tried, compared, partial, diverged per kind
npm run audit:corpus -- --shard=1/4 --total=500 --json=s1.json   # shard 1 of 4 over seeds 1-500, split evenly
npm run audit:corpus -- --merge s0.json s1.json --total=500      # shards added up; fails on a seed missed or run twice

audit:corpus runs the same audit on random games of three kinds (plain, with free items, with three characters and free items). partial (the explicit search hit --max) is not a failure: those verdicts are just not compared, and the counts say so.

prove:matrix and bench (engine repository)

# in the engine repository only
npm run prove:matrix -- --only=c11,o21 --time=600 --mem=4096 --json=m.json --profile=docs/dev/PROOF-PROFILE.md
npm run bench -- --matrix --eras --max=20000
npm run bench -- --rooms=40 --prove --v3

• prove:matrix (4.1.13): the twelve instances of the proof matrix, each in its own process under the published budgets (10 000 000 states, --time 600 s on the maintainer's Mac and 1 200 s on the runner, --mem 4 096 MB). Exit 1 on a false verdict; an instance out of budget is unknown, the gap report, not a failure. Also --representation=objects|compact, --checkpoint-dir=<dir> and --workers=N, passed on. Nightly only.
• bench -- --matrix [--eras] [--max=20000]: the 3.3 reference table, the proof on 20 or 40 rooms × 1, 2 or 3 characters, and where the time goes (--eras: characters confined to eras).
• bench -- --rooms=40 [--prove --v3]: a generated game of that size, every tool timed on it; --prove adds the exhaustive proof, --v3 generates it with stable ids. The weekly prove workflow runs it on 100 rooms.

The measures are in Benchmarks.

The solver's heavy tests (engine repository)

npm test runs the Node tests of the engine, the tools and the selected game, without the CPU-bound solver tests. npm run test:heavy runs those (the abstraction audits, the canonical owner, the memo and ownership proofs, the reference chapter's proof, the solver oracle, dominance, partitions, the checkpoint matrix): every night, minutes each. See Which tests run when.

Related identifiers

• npm run validate, npm run lint, npm run verify:game, npm run prove:game: Checking your game.
• npm run replay: Checking your game.
• npm run solve:reality: What the solver proves.
• PROOF_CACHE, PROOF_CACHE_DIR: Environment variables.

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