build: add a make cover target for per-function coverage (closes #17)

make cover writes build/coverage.out and prints the per-function report;
make cover-html renders the same profile to build/coverage.html. The
per-package percentage make test prints cannot say which function is
untested.

Both write files, so neither is in check, and neither may be added to it:
check must not modify the working tree. Their output lands under the
already-ignored build/.

Verified: make cover printed per-function lines and a 62.6% total,
make cover-html wrote build/coverage.html, and git status stayed clean.
GOFLAGS=-count=1 make check green in 24s with the lint layer executing
(12.0s, "0 issues.", not CACHED) and the suite running for real (cmd/rogue
1.037s, game 3.410s); check is still fmt-check lint test and git status is
clean afterwards.

.dockerignore

@@ -0,0 +1,8 @@
+# Part of the lint gate: only what reaches the container is linted, so
+# excluding a self-contained Go source here drops it from the lint silently.
+# Never exclude Go sources, go.mod/go.sum or .golangci.yml.
+.git
+
+# Generated artifacts only; `make build` puts a multi-megabyte binary here
+# and it would otherwise be shipped into the build context.
+/build/

.gitignore

@@ -1,4 +1,5 @@
 *.log
 *.out
 *.test
+/build/
 /rogue

Dockerfile.lint

@@ -0,0 +1,20 @@
+# Lint image, built by script/lint: golangci-lint runs as a build step, so
+# a successful build is a clean lint.
+
+# golangci/golangci-lint:v2.12.2 (Debian-based), 2026-08-07
+FROM golangci/golangci-lint:v2.12.2@sha256:5cceeef04e53efe1470638d4b4b4f5ceefd574955ab3941b2d9a68a8c9ad5240 AS deps
+
+WORKDIR /src
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+# This stage must stay the one that runs golangci-lint, and its name must
+# match $stage in script/lint. --target halts the build at this stage, so
+# moving the lint step to another stage, or adding a stage after this one,
+# is not caught.
+FROM deps AS lint
+
+COPY . .
+
+RUN golangci-lint run --config .golangci.yml ./...

Makefile

@@ -1,18 +1,47 @@
 # Development convenience targets. This repo is exempt from the standard
-# policy scaffold (no Dockerfile, CI, or REPO_POLICIES.md); this Makefile
+# policy scaffold (no CI config, no REPO_POLICIES.md, no application
-# is only a thin wrapper around the Go toolchain, golangci-lint, and
+# Dockerfile) except for the lint container: per sneak's 2026-08-09
-# prettier so `make fmt` / `make check` behave the same as in sneak's
+# ruling, linting runs in docker only, so Dockerfile.lint and script/lint
-# other repos.
+# are part of this repo. This Makefile is otherwise only a thin wrapper
+# around the Go toolchain and prettier so `make fmt` / `make check` behave
+# the same as in sneak's other repos.
 
-GO_PKGS  := ./...
+GO_PKGS   := ./...
-MD_FILES := $(shell git ls-files '*.md')
+MD_FILES  := $(shell git ls-files '*.md')
-PRETTIER := prettier --tab-width 4 --prose-wrap always
+PRETTIER  := prettier --tab-width 4 --prose-wrap always
 
-.PHONY: check fmt fmt-check lint test
+# Every generated artifact goes here, and the whole directory is
+# git-ignored. Targets that write outside it can commit their output.
+BUILD_DIR := build
+BIN       := $(BUILD_DIR)/rogue
+COVERPROF := $(BUILD_DIR)/coverage.out
+COVERHTML := $(BUILD_DIR)/coverage.html
 
-# Format, lint, and test — the full local pre-commit gate.
+.PHONY: build check cover cover-html fmt fmt-check lint test
+
+# Format, lint, and test — the full local pre-commit gate. Keep this list
+# to targets that write nothing into the working tree.
 check: fmt-check lint test
 
+# Build the executable into $(BUILD_DIR). `go build -o` does not create the
+# parent directory.
+build:
+	@mkdir -p $(BUILD_DIR)
+	go build -o $(BIN) ./cmd/rogue
+
+# Per-function coverage, for finding which functions are untested. The
+# percentage `make test` prints is a per-package total and cannot answer
+# that. Writes files, so it stays out of `check`.
+cover:
+	@mkdir -p $(BUILD_DIR)
+	go test -timeout 30s -coverprofile=$(COVERPROF) $(GO_PKGS)
+	go tool cover -func=$(COVERPROF)
+
+# Render the same profile as annotated source.
+cover-html: cover
+	go tool cover -html=$(COVERPROF) -o $(COVERHTML)
+	@echo "wrote $(COVERHTML)"
+
 # Format Go and Markdown in place.
 fmt:
 	gofmt -w .
@@ -26,9 +55,11 @@ fmt-check:
 	fi
 	$(PRETTIER) --check $(MD_FILES)
 
-# Run the house linter (config in .golangci.yml).
+# Run the house linter. golangci-lint is never installed on the host: the
+# work happens inside the pinned container built by Dockerfile.lint, and
+# this target is a thin shim over the script that builds it.
 lint:
-	golangci-lint run $(GO_PKGS)
+	./script/lint
 
 # Run the test suite. Quiet on success; on failure, rerun verbosely for the
 # full output and still fail the target (the first run already proved the

README.md

@@ -21,19 +21,19 @@ original program structure and the design of this port.
 Requires Go 1.25 or later and a terminal at least 80x24.
 
 ```bash
-go build ./cmd/rogue
+make build
-./rogue
+./build/rogue
 ```
 
 ```bash
 # Restore a saved game
-./rogue ~/rogue.save
+./build/rogue ~/rogue.save
 
 # View high scores
-./rogue -s
+./build/rogue -s
 
 # Test the death screen (demo mode)
-./rogue -d
+./build/rogue -d
 ```
 
 ## In-game commands
@@ -57,7 +57,7 @@ Press `?` in game for the full list.
 export ROGUEOPTS="name=YourName,terse,jump,fruit=mango"
 
 # Wizard (debug) mode, with a reproducible dungeon
-ROGUE_WIZARD=1 SEED=12345 ./rogue
+ROGUE_WIZARD=1 SEED=12345 ./build/rogue
 ```
 
 The scoreboard is kept in `~/.rogue.scores`. Save files are Go gob snapshots
@@ -77,10 +77,14 @@ sequences, dungeon-generation golden checks, and an RNG compatibility test
 against the original C generator.
 
 For development, the `Makefile` wraps the toolchain: `make fmt` (gofmt +
-prettier), `make lint` (golangci-lint), `make test` (the suite, under the race
+prettier), `make lint` (`script/lint`, which runs golangci-lint inside the
-detector with coverage and a timeout), and `make check` (all three). Use the
+pinned container built from `Dockerfile.lint` — it is never installed on the
-targets rather than invoking `go test` directly — they carry the flags the
+host, so docker is required), `make test` (the suite, under the race detector
-project relies on.
+with coverage and a timeout), `make check` (all three), `make build` (the
+executable), and `make cover` / `make cover-html` (per-function coverage, and
+the same profile as annotated source at `build/coverage.html`). Everything they
+generate lands in the git-ignored `build/`. Use the targets rather than the
+toolchain directly — they carry the flags the project relies on.
 
 ## License
 

TODO.md

@@ -29,12 +29,186 @@ Refactor ground rules:
 
 # Next Step
 
-Broaden unit test coverage where playtesting finds thin spots — wizard commands
+Tag a release once a full game (Amulet retrieval and score entry) completes
-(#7). Rings and sticks, the first two thirds of this step, are done; see the top
+without defects. Promoted from Future Steps now that the coverage step above it
-of Completed Steps.
+is finished.
 
 # Completed Steps
 
+- 2026-08-10 `make cover` added (https://git.eeqj.de/sneak/rgoue/issues/17).
+  `make cover` writes `build/coverage.out` and prints the per-function report;
+  `make cover-html` renders the same profile to `build/coverage.html`. The
+  per-package percentage `make test` prints cannot say _which_ function is
+  untested, which is how the coverage gaps closed so far had to be found — by
+  grepping test files for identifiers.
+
+    Neither target is in `check`, and neither may be added to it: both write
+    files, and `make check` must not modify the working tree.
+
+- 2026-08-10 `make build` added (https://git.eeqj.de/sneak/rgoue/issues/19). The
+  executable is built to `build/rogue`; `README.md` no longer contains a raw
+  `go` invocation anywhere. `build` is in neither `check` nor `test` —
+  `make check` stays `fmt-check lint test` and still writes nothing into the
+  working tree.
+
+    Generated artifacts now all live under `build/`, which `.gitignore` covers
+    as a whole. Anything written outside it is committable, so a target that
+    puts its output elsewhere reintroduces the stray-artifact problem.
+
+- 2026-08-10 Linting moved into a container
+  (https://git.eeqj.de/sneak/rgoue/issues/41). `golangci-lint` is no longer
+  invoked on the host anywhere in the repo: `Dockerfile.lint` pins
+  `golangci/golangci-lint:v2.12.2` by digest and runs the linter as a build
+  step, so a successful build is a clean lint, and `make lint` is now a shim
+  over `script/lint`. This is what killed the false green seen earlier, where a
+  branch that was genuinely red with a `goconst` finding reported `0 issues` off
+  the shared host cache; a container per run has its own cache and lock.
+
+    `script/lint` builds with `--target "$stage"`, `--no-cache-filter="$stage"`
+    and `--output=type=cacheonly`. The durable property to check when touching
+    any of this: the lint stage executes on every run and is never served from
+    cache. Three things no tooling checks, left to whoever edits the gate —
+    `$stage` must match the stage name in `Dockerfile.lint`; that stage must
+    stay the one running `golangci-lint`, since `--target` halts the build
+    there; and `.dockerignore` governs what reaches the container, so excluding
+    a self-contained Go source drops it from the lint silently.
+
+    Verified rather than assumed, since a green docker build is the classic
+    false green: two consecutive runs on an unchanged tree each showed the
+    `golangci-lint run` layer executing and reporting `0 issues.` while the
+    `deps` layers reported `CACHED`; the same build with `--no-cache-filter`
+    removed reported that layer `CACHED`, so the re-execution is attributable to
+    the flag rather than to a changed context; deliberate violations failed the
+    build naming the specific finding and reverted clean; a stage-name typo
+    failed loudly at exit 1; and a Go file excluded via `.dockerignore` reported
+    `0 issues.` at exit 0 with the violation still in the tree. Wall-clock
+    durations vary per host and per run, so they are not recorded here.
+
+- 2026-08-09 `TestAutoSaveOnSignalRacesTurnLoop` de-flaked at the cause
+  (`fix/autosave-turn-budget-36`, closes #36). The failure text was captured
+  before anything was changed and it is **not** a data race: the assertion was
+  `driveUntilDone`'s
+  `t.Fatal("the turn loop ran out of turns before the saves were taken")`, with
+  no `WARNING: DATA RACE` anywhere in the log. The handoff fixed in #24 was
+  working; the test's own drive loop was running out of its fixed 1000-turn
+  budget first.
+
+    Confirmed rather than taken on trust. Instrumenting the loop to report the
+    turns it actually used showed the count tracking scheduling pressure and
+    nothing else: about 60-120 turns at host load ~57 with the whole machine to
+    spread over, 418 at `GOMAXPROCS=4`, 539 and 655 at 2 and 1, and past 1000 —
+    the recorded failure — under the doubled load of the verbose rerun that the
+    test target performs after a failure. The turns between one save being
+    answered and the next request arriving are not work; they are the saving
+    goroutine's wake-up latency, so a fixed turn count is a wall-clock
+    assumption in disguise, which is why raising it would have hidden the flake
+    rather than fixed it.
+
+    So the budget is gone rather than larger. `driveUntilDone` now drives until
+    the saving goroutine finishes and nothing else. Termination is not lost, it
+    just belongs to the code under test instead of to the test: every
+    `AutoSaveOnSignal` returns within the timeout it is handed, so the saving
+    goroutine always finishes. A handoff that has stopped answering costs one
+    `autoSaveWait` in total — `g.sigSave` is one deep, so an unserviced request
+    stays in the channel and every later call finds it full and fails at once —
+    and the failure is then the real assertion (`saves taken = 0, want 25`)
+    instead of "out of turns". The worst case is not that one: a handoff that
+    drains each request but slower than `autoSaveWait` costs one timeout per
+    save, `wantSaves × autoSaveWait` = 250s, which would run past the 30s
+    package timeout instead of reaching the assertion. It takes ~10s of
+    scheduler starvation per save against a measured 0.12s per 1000 turns, so it
+    is remote, and the turn cap did not bound it either. The comment in the test
+    states that bound rather than the optimistic one.
+
+    Removing the cap exposed a second assumption underneath it, which is the
+    reason this is not a one-line diff. `testTerm` answers space and newline for
+    ever once its script is exhausted, and neither key takes a turn, so
+    `command()` — which loops until the player consumes one — never returns; the
+    old cap was silently sized to the script (4000 characters, two per turn,
+    against 1000 turns). An uncapped drive wedged inside a single `command()`
+    call. The two drive tests therefore use a new `driveTerm`, a headless
+    terminal whose script repeats. Repeating is necessary but not sufficient,
+    and the test says so: `' '` clears `After` outright and all eight movement
+    keys clear it on a refused step, so a script of only those keys wedges just
+    as `testTerm`'s tail did. What makes the wedge impossible is that the cycle
+    always holds an _unconditional_ turn-taker, and these scripts hold two —
+    `'.'` (empty handler) and `'s'` (`search`, which writes `After` on no path),
+    neither refusable by blocked-in-all-directions, `Held`, a bear trap, or
+    `NoCommand > 0`. Removing both would bring the wedge back.
+
+    Both halves of the definition of done were demonstrated by mutation, with
+    the deliberately-broken tree reverted afterwards and `.golangci.yml` left
+    byte-identical (sha256 `021cc83f...46bcb`). Reverting #24 —
+    `AutoSaveOnSignal` replaced by a direct `g.autoSave()`, encoding on the
+    calling goroutine — still fails the test with 139 `WARNING: DATA RACE`
+    reports naming `snapshotHeader` reading what `executeCommand` writes, so the
+    guard is undiminished. Removing the `serviceAutoSaveRequest` call from
+    `command()` still fails it too, now in 10s with `saves taken = 0, want 25`
+    rather than by hanging.
+
+    Under load, an A/B at `GOMAXPROCS=2` on a 48-core host at load ~150, with an
+    unrelated deliberate failure in the tree so that every run took the verbose
+    rerun: the old code failed 8 of 8 runs with "ran out of turns"; the new code
+    failed 0 of 8, the only failure being the planted one. Also green across 24
+    concurrent unconstrained runs at load ~120, 10 runs alongside a spinner
+    load, and 5 runs each at `GOMAXPROCS` 1, 2 and 4. `make check` green, lint 0
+    issues.
+
+- 2026-08-09 Wizard commands under test (`test/wizard-coverage`, closes #7): the
+  last of the three thin spots, so the coverage step is now closed rather than
+  narrowed. `game/wizard.go`'s eight functions had no tests of their own, and
+  the file is not purely a debug surface — `set_know` writes the per-game
+  discovered tables that name items in ordinary play, and `teleport` is what the
+  teleport ring calls every fiftieth turn. Package coverage 60.6% -> 62.4%.
+  Everything expected was transcribed from `wizard.c`, `command.c` (the
+  `CTRL('I')` kit), `extern.c` (`a_class[]`), `weapons.c` (`init_dam[]`) and
+  `rogue.h`; 30 mutations were tried and all 30 were caught.
+
+    Two findings came out of the reading. (1) **A wizard-created cursed weapon
+    is not cursed, in C or here.** `create_obj` sets `ISCURSED` and then calls
+    `init_weapon`, which _assigns_ `weap->o_flags = iwp->iw_flags` and so
+    overwrites the bit it just set; only the `o_hplus` penalty survives, and the
+    "cursed" weapon can still be dropped and unwielded. The port reproduces this
+    exactly. The test asserts the whole flag word comes back as the `init_dam[]`
+    row's value whatever blessing was answered, and deleting the `ISCURSED` line
+    from the port leaves every weapon test green — which is the evidence that
+    the line is dead for weapons. The armor arm has no such clobber and does
+    keep the curse. (2) **`show_map`'s standout is asymmetric in C and symmetric
+    here.** C tests `!(real & F_REAL)` before drawing and `!real` — the whole
+    flag word — after. `new_level` seeds every square with `p_flags = F_REAL`,
+    and exactly three sites clear that bit. `passages.c putpass` sets `F_PASS`
+    first, so its secret passage is left at `0x80`. `passages.c door`'s
+    secret-door arm clears it on a room-wall exit whose flags are still exactly
+    `F_REAL` (`rooms.c` writes no `p_flags` at all), leaving `p_flags == 0`; its
+    per-square gate is `rnd(5) == 0` against `putpass`'s `rnd(40) == 0`, and
+    `game/passages.go`'s `door` reproduces it. `new_level`'s trap loop then ORs
+    in `rnd(NTRAPS)`, which is `abs((int) RN) % 8` and so yields `0..7`, and
+    `T_DOOR` is `00` — an unsprung trapdoor square is also exactly zero
+    (`be_trapped` is what later ORs `F_SEEN` into it). So C _does_ turn standout
+    off again, at secret doors and unsprung trapdoors; what it gets wrong is
+    leaking the attribute forward from a secret passage or a non-trapdoor trap
+    until it reaches one of those. Intermittent bands of reverse video, not a
+    permanently reversed map. `game/wizard.go` tests `isReal` both times and
+    highlights the one square. That is a display-only difference in a
+    wizard-only command and was reported on the issue rather than changed here;
+    the test asserts the map characters unconditionally but the standout
+    attribute only up to the first secret square, so it pins nothing that C
+    contradicts.
+
+    Two things the tests had to be built around. The `insist` arm of `whatis` is
+    a loop whose only exits are picking a matching item and `n_objs == 0`, so a
+    script that runs dry hangs instead of failing — every sequence that can
+    re-prompt ends in an abort tail, the `n_objs == 0` exit is reached the way a
+    player reaches it (`*` for a list with nothing appropriate in the pack)
+    rather than by poking the counter, and the one mutation that deletes that
+    exit is the only one of the 30 that fails by timeout instead of fast,
+    necessarily so. And `show_map` does **not** mark squares seen — it writes
+    into `hw` and touches no `PLACE` at all — so the issue's wording for it
+    could not be tested as written; the loop bounds are asserted instead by
+    planting a marker in the rows C's loop excludes, since those rows are blank
+    on a real level and copying blanks over blanks would have made the bound
+    unfalsifiable.
+
 - 2026-08-09 Wands and staffs under test (`test/sticks-coverage`, closes #6):
   the second of the three thin spots the Next Step names. `game/sticks.go` was
   the largest under-tested file in the repo — 534 lines, 23 functions, one test
@@ -580,7 +754,11 @@ of Completed Steps.
   24 long lines wrapped or their comments tightened, control bytes in
   `term/tcell.go` as character literals, and two `wsl_v5` defer cuddles. The
   repo has no golangci-lint version pin to bump (no Dockerfile or CI;
-  `make lint` runs whatever `golangci-lint` is on the host).
+  `make lint` runs whatever `golangci-lint` is on the host). Superseded
+  2026-08-10: there is a pin now, and no host lint path — `Dockerfile.lint` pins
+  the linter image by digest and `script/lint` runs it in a container. See the
+  2026-08-10 entry at the top of this section
+  (https://git.eeqj.de/sneak/rgoue/issues/41).
 
 - 2026-07-24 Seed compatibility — item tables (seed-compat): instrumented the C
   reference on modern-rogue with a DUMP mode (testdata/c_seedcompat.patch) that
@@ -724,13 +902,17 @@ of Completed Steps.
 
 # Future Steps
 
-1. Tag a release once a full game (Amulet retrieval and score entry) completes
+1. Full-terminal-size support (deferred by explicit decision 2026-07-06):
-   without defects.
-2. Full-terminal-size support (deferred by explicit decision 2026-07-06):
    per-game dungeon dimensions instead of the 80x24 constants; open design
    questions are resize policy, gameplay tuning at larger sizes, and a --classic
    80x24 mode.
-3. Note: this repo is exempt from the standard policy scaffold. A minimal dev
+2. Note: this repo is exempt from the standard policy scaffold, but the
-   Makefile (fmt/fmt-check/lint/test/check targets) exists per sneak's
+   exemption is narrower than it was. A minimal dev Makefile
-   2026-07-07 request, but do not add a Dockerfile, CI config, or
+   (fmt/fmt-check/lint/test/check targets) exists per sneak's 2026-07-07
-   REPO_POLICIES.md.
+   request. `Dockerfile.lint` and `script/lint` are now also permitted, and
+   required, along with the `.dockerignore` that scopes their build context:
+   sneak's 2026-08-09 ruling (https://git.eeqj.de/sneak/rgoue/issues/41) is that
+   every repo lints in a container invoked through `script/lint`, and being
+   later and explicit it overrides the 2026-07-07 exemption for those three
+   files only. Still do not add: CI config, `REPO_POLICIES.md`, an application
+   `Dockerfile`, or any other `script/` entrypoint.

game/autosave_test.go

@@ -9,7 +9,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"strings"
 	"testing"
 	"time"
 )
@@ -17,7 +16,9 @@ import (
 // autoSaveWait is the deadline the tests hand AutoSaveOnSignal when they
 // expect the save to be taken. It is long enough that a loaded machine
 // cannot turn a working handoff into a spurious failure, and it is never
-// actually waited out on a passing run.
+// actually waited out on a passing run. It is also what bounds
+// driveUntilDone, by way of the saving goroutine it waits for — see
+// there for what that bound comes to.
 const autoSaveWait = 10 * time.Second
 
 // TestAutoSaveOnSignalRacesTurnLoop is the test issue #24 exists for: it
@@ -34,12 +35,14 @@ const autoSaveWait = 10 * time.Second
 func TestAutoSaveOnSignalRacesTurnLoop(t *testing.T) {
 	t.Parallel()
 
-	// Same mix as TestTurnLoopCrashSweep: the spaces answer any --More--
+	// Same mix as TestTurnLoopCrashSweep — the spaces answer any --More--
-	// prompt, and the script is long enough that the drive never runs it
+	// prompt — on a driveTerm, so the drive can run for as long as the
-	// out.
+	// saves take rather than for as long as a script lasts. The '.' and
-	script := []byte(strings.Repeat("h j k l y u b n s . ", 400))
+	// the 's' are what make an unbounded drive safe, and at least one of
+	// the two has to stay in the cycle: see driveTerm.
+	term := &driveTerm{script: []byte("h j k l y u b n s . ")}
 
-	g := New(Params{Seed: 20260809, Term: &testTerm{input: script}})
+	g := New(Params{Seed: 20260809, Term: term})
 	g.FileName = filepath.Join(t.TempDir(), "rogue.save")
 	g.startLevel()
 	g.prePlay()
@@ -74,14 +77,50 @@ func TestAutoSaveOnSignalRacesTurnLoop(t *testing.T) {
 
 // driveUntilDone runs turns until the saving goroutine is finished,
 // fortifying the hero each turn so no death exits the test binary. The
-// turn cap keeps a broken handoff from hanging the suite instead of
+// condition it waits on is that goroutine finishing — nothing else.
-// failing it.
+//
+// It used to stop after a fixed 1000 turns and fail, and that cap was a
+// load-sensitive assumption wearing a counter's clothes (issue #36). The
+// turns this loop spends between one save request being answered and the
+// next arriving are not work; they are the saving goroutine's scheduling
+// latency, so the turn count 25 saves costs is a function of how
+// contended the machine is rather than of anything the code under test
+// does. Measured here on a 48-core host at load ~57: about 60-120 turns
+// with a whole machine to spread over, 418 to 655 as GOMAXPROCS was cut
+// from 4 to 1, and past 1000 under the doubled load of the verbose
+// rerun, which is the flake this replaces. A budget that has to be
+// guessed cannot be guessed right, so there is no budget.
+//
+// Dropping it costs no termination guarantee, because the bound belongs
+// to the code under test and not to this loop: each AutoSaveOnSignal
+// call returns within the timeout the caller hands it, so the saving
+// goroutine always finishes and done always closes. That bound is worth
+// stating exactly, because it is not one autoSaveWait.
+//
+// A handoff that has stopped answering altogether costs one, in total,
+// however many saves were asked for. g.sigSave
+// is one deep, so the unserviced request stays in the channel and every
+// later call finds it full and reports failure immediately — measured
+// at 10.0s for 25 saves with the service point deleted from command().
+// What fails is then the caller's own assertion, the count of saves
+// actually taken, which says far more than "out of turns" ever did.
+//
+// A handoff that still drains every request but takes longer than
+// autoSaveWait to do it is the worst case, and costs one timeout per
+// save: wantSaves * autoSaveWait, 250s at these constants, which would
+// run past the package timeout rather than reach the assertion. It
+// takes about ten seconds of scheduler starvation per save to get
+// there, against a regime measured at 0.12s per 1000 turns, so it is
+// remote — and the 1000-turn cap did not bound it either, a turn count
+// being no kind of time bound. `go test -timeout 30s` is the backstop
+// under all of it.
+//
+// The one thing the caller does have to supply is a terminal that can
+// feed an unbounded drive: see driveTerm.
 func driveUntilDone(t *testing.T, g *RogueGame, done <-chan struct{}) {
 	t.Helper()
 
-	const maxTurns = 1000
+	for {
-
-	for range maxTurns {
 		select {
 		case <-done:
 			return
@@ -91,8 +130,6 @@ func driveUntilDone(t *testing.T, g *RogueGame, done <-chan struct{}) {
 		fortify(g)
 		g.command()
 	}
-
-	t.Fatal("the turn loop ran out of turns before the saves were taken")
 }
 
 // TestAutoSaveOnSignalWhileBlockedOnInput is the case the fix is really
@@ -266,9 +303,7 @@ func TestAutoSaveOnSignalTimesOutLeavingTheOldSave(t *testing.T) {
 func TestAutoSaveOnSignalWithoutASaveFile(t *testing.T) {
 	t.Parallel()
 
-	g := New(Params{Seed: 5, Term: &testTerm{
+	g := New(Params{Seed: 5, Term: &driveTerm{script: []byte("s . ")}})
-		input: []byte(strings.Repeat("s . ", 200)),
-	}})
 	g.FileName = ""
 	g.startLevel()
 	g.prePlay()
@@ -437,6 +472,66 @@ func mkBlockedGame(t *testing.T, term Terminal) *RogueGame {
 	return g
 }
 
+// driveTerm is a headless Terminal whose script repeats instead of
+// running out, for the tests that drive the turn loop until something
+// else finishes rather than for a set number of turns.
+//
+// testTerm cannot do that job. Once its script is exhausted it answers
+// space and newline for ever, and neither takes a turn, so command() —
+// which loops until the player does something that consumes one, the
+// `if !g.After { ntimes++ }` in command.c — never returns. A drive with
+// a turn cap sized to its script never notices; a drive that runs until
+// the saves are taken wedges inside a single command() call, which is
+// what a first attempt at issue #36 did.
+//
+// Repeating the script is necessary but nowhere near sufficient, and
+// the difference is what anyone editing one of these scripts has to
+// know. Most keys take a turn only conditionally. ' ' is the "legal
+// illegal command" and clears After outright (tables.go). All eight
+// movement keys clear it whenever the step is refused: a wall or the
+// map edge (move.go moveResolve), an illegal diagonal (moveTarget), or
+// a confused step that lands back in place (moveHero). A script of
+// nothing but those keys wedges exactly the way testTerm's tail does,
+// repetition or no repetition — with the script set to just " " this
+// drive hits the 30s package timeout inside command().
+//
+// What actually makes the wedge impossible is that the cycle always
+// contains at least one *unconditional* turn-taker, and the scripts
+// here carry two: '.', the rest command, whose handler is empty, and
+// 's', search, which writes After on no path. Nothing refuses either
+// one — not being blocked in all eight directions, not Held, not stuck
+// in a bear trap, and not NoCommand > 0, where playTurn skips
+// executeCommand altogether and After is simply left true. Trim both
+// out and the wedge this test exists to remove comes straight back.
+//
+// One further precondition, from what this fake does not supply:
+// testTerm's tail answered a newline every other read and this does
+// not. Nothing reachable from these scripts asks for one — waitFor('\n')
+// sits on the death and score paths (rip.go, score.go), which fortify
+// prevents from ever being reached — but a script that could reach them
+// would park in waitFor for ever.
+type driveTerm struct {
+	script []byte
+	pos    int
+}
+
+func (t *driveTerm) Render(*Window) {}
+
+func (t *driveTerm) Repaint() {}
+
+func (t *driveTerm) Fini() {}
+
+// Interrupt has nothing to wake: this terminal's ReadChar never blocks.
+func (t *driveTerm) Interrupt() {}
+
+// ReadChar hands out the next scripted key, wrapping at the end.
+func (t *driveTerm) ReadChar() (byte, bool) {
+	ch := t.script[t.pos]
+	t.pos = (t.pos + 1) % len(t.script)
+
+	return ch, true
+}
+
 // blockingTerm is a Terminal that genuinely blocks in ReadChar until a
 // key is pushed or Interrupt wakes it — which testTerm, whose reads never
 // block, cannot reproduce.

game/wizard_test.go

@@ -6,6 +6,8 @@ import (
 	"errors"
 	"os"
 	"path/filepath"
+	"slices"
+	"strconv"
 	"testing"
 )
 
@@ -530,3 +532,962 @@ func TestWizardToggleWithoutWizardSaysSorry(t *testing.T) {
 		t.Error("'+' consumed a turn; C sets after = FALSE")
 	}
 }
+
+// The rest of this file covers game/wizard.go proper (issue #7). Every
+// expected value below is transcribed from origin/c-master — wizard.c for
+// create_obj/whatis/set_know/teleport/show_map, command.c for the CTRL('I')
+// kit, extern.c for a_class[], weapons.c for init_dam[], and rogue.h for
+// the R_* numbering and the F_* place flags — never from what the port
+// happens to return.
+//
+// Two shapes recur. Scripted input always ends with an abort tail (a space
+// for a --More--, then ESCAPE), because testTerm.ReadChar hands out filler
+// forever once the script runs dry and a re-prompting loop would spin to
+// the suite timeout instead of failing. And where C issues no prompt at
+// all, the test asserts on the scripted input cursor rather than on state:
+// a stray readchar would eat the next answer and desynchronise everything
+// after it, which no state assertion would notice.
+
+// mkWizard builds a headless game in wizard mode the way the program does.
+// cmd/rogue/main.go turns ROGUE_WIZARD into Params.Wizard and New consumes
+// that field, so no test here pokes g.Wizard. depth is what decides
+// whether the generator produces secret (non-F_REAL) squares at all.
+func mkWizard(t *testing.T, seed int32, depth int) *RogueGame {
+	t.Helper()
+
+	g := New(Params{Seed: seed, Wizard: true, Term: &testTerm{}})
+	if !g.Wizard {
+		t.Fatal("Params.Wizard did not turn on wizard mode")
+	}
+
+	g.Depth = depth
+	g.NewLevel()
+	g.Oldpos = g.Player.Pos
+	g.Oldrp = g.roomIn(g.Player.Pos)
+
+	return g
+}
+
+// packSet snapshots pack membership by identity. add_pack files a new item
+// in kind order, so its position is no guide to which one it is.
+func packSet(g *RogueGame) map[*Object]bool {
+	seen := make(map[*Object]bool, len(g.Player.Pack))
+	for _, o := range g.Player.Pack {
+		seen[o] = true
+	}
+
+	return seen
+}
+
+// onlyNewItem returns the single object added to the pack since before.
+func onlyNewItem(t *testing.T, g *RogueGame, before map[*Object]bool) *Object {
+	t.Helper()
+
+	var made []*Object
+
+	for _, o := range g.Player.Pack {
+		if !before[o] {
+			made = append(made, o)
+		}
+	}
+
+	if len(made) != 1 {
+		t.Fatalf("pack gained %d objects, want exactly 1", len(made))
+	}
+
+	return made[0]
+}
+
+// inputUsed reports how many scripted keys have been consumed so far.
+func inputUsed(t *testing.T, g *RogueGame) int {
+	t.Helper()
+
+	tt, ok := g.scr.term.(*testTerm)
+	if !ok {
+		t.Fatal("game terminal is not a testTerm")
+	}
+
+	return tt.pos
+}
+
+// TestCreateObjFilesTheItemInThePack covers the tail every arm of
+// wizard.c create_obj shares: o_group = 0, o_count = 1, then
+// add_pack(obj, FALSE). A potion is the kind C's switch does nothing for,
+// so nothing else is in the way.
+func TestCreateObjFilesTheItemInThePack(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 21, 1)
+	before := packSet(g)
+
+	setInput(t, g, Potion, '0', ' ', Escape)
+	g.createObj()
+
+	made := onlyNewItem(t, g, before)
+
+	if made.Kind != KindPotion || made.Which != int(PotionConfusion) {
+		t.Fatalf("created %v which %d, want %v which %d",
+			made.Kind, made.Which, KindPotion, int(PotionConfusion))
+	}
+
+	if made.Count != 1 {
+		t.Errorf("count = %d, want the 1 C sets", made.Count)
+	}
+
+	if made.Group != 0 {
+		t.Errorf("group = %d, want the 0 C sets", made.Group)
+	}
+
+	if made.PackCh == 0 {
+		t.Error("created object has no pack letter: add_pack never filed it")
+	}
+}
+
+// TestCreateObjGoldAsksHowMuch covers the GOLD arm, C's
+// msg("how much?") followed by get_num(&obj->o_goldval, stdscr).
+func TestCreateObjGoldAsksHowMuch(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 22, 1)
+	before := packSet(g)
+
+	setInput(t, g, Gold, '0', '2', '5', '0', '\n', ' ', Escape)
+	g.createObj()
+
+	made := onlyNewItem(t, g, before)
+
+	if made.Kind != KindGold {
+		t.Fatalf("created %v, want %v", made.Kind, KindGold)
+	}
+
+	if made.GoldValue != 250 {
+		t.Errorf("gold value = %d, want the typed 250", made.GoldValue)
+	}
+}
+
+// TestCreateWeaponBlessing pins the weapon arm of create_obj to C:
+//
+//	if (bless == '-') obj->o_flags |= ISCURSED;
+//	if (obj->o_type == WEAPON) {
+//	    init_weapon(obj, obj->o_which);
+//	    if (bless == '-') obj->o_hplus -= rnd(3)+1;
+//	    if (bless == '+') obj->o_hplus += rnd(3)+1;
+//
+// A curse subtracts and a blessing adds — the opposite of the armor arm
+// below, and rnd(3)+1 is 1..3 either way.
+//
+// The curse itself does not survive on a weapon, and that is C's own
+// behavior, not a port bug: weapons.c init_weapon *assigns*
+// weap->o_flags = iwp->iw_flags, so it overwrites the ISCURSED bit set
+// three lines earlier with the init_dam[] row's flags. A wizard-created
+// "cursed" weapon therefore carries only the hit penalty and can still be
+// dropped and unwielded. The mace row's flags are 0, so the whole word
+// must come back 0 here whatever was answered. The armor arm has no such
+// clobber, which is why TestCreateArmorBlessing does expect ISCURSED.
+func TestCreateWeaponBlessing(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name    string
+		bless   byte
+		low, hi int
+	}{
+		{"no blessing", 'n', 0, 0},
+		{"blessed adds to the hit bonus", '+', 1, 3},
+		{"cursed subtracts from it", '-', -3, -1},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 23, 1)
+			obj := newObject()
+			obj.Kind = KindWeapon
+			obj.Which = int(WeaponMace)
+
+			setInput(t, g, tc.bless, ' ', Escape)
+			g.createWeaponArmor(obj)
+
+			if obj.Flags != 0 {
+				t.Errorf("flags = %d, want the init_dam mace row's 0: "+
+					"init_weapon assigns o_flags over any curse",
+					obj.Flags)
+			}
+
+			if obj.HPlus < tc.low || obj.HPlus > tc.hi {
+				t.Errorf("hit bonus = %d, want %d..%d",
+					obj.HPlus, tc.low, tc.hi)
+			}
+
+			// init_weapon ran: the mace row of C's init_dam[].
+			if got := obj.Damage.String(); got != "2x4" {
+				t.Errorf("damage = %q, want the init_dam mace row 2x4", got)
+			}
+
+			if got := obj.HurlDmg.String(); got != "1x3" {
+				t.Errorf("hurl damage = %q, want 1x3", got)
+			}
+		})
+	}
+}
+
+// TestCreateArmorBlessing pins the armor arm, where C moves o_arm the
+// other way because a lower armor class is better:
+//
+//	obj->o_arm = a_class[obj->o_which];
+//	if (bless == '-') obj->o_arm += rnd(3)+1;
+//	if (bless == '+') obj->o_arm -= rnd(3)+1;
+//
+// extern.c's a_class[] has PLATE_MAIL at 3, so the three answers land at
+// 3, 0..2 and 4..6.
+func TestCreateArmorBlessing(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name    string
+		bless   byte
+		cursed  bool
+		low, hi int
+	}{
+		{"no blessing leaves the table value", 'n', false, 3, 3},
+		{"blessed lowers the armor class", '+', false, 0, 2},
+		{"cursed raises it", '-', true, 4, 6},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 24, 1)
+			obj := newObject()
+			obj.Kind = KindArmor
+			obj.Which = int(ArmorPlateMail)
+
+			setInput(t, g, tc.bless, ' ', Escape)
+			g.createWeaponArmor(obj)
+
+			if got := obj.Flags.Has(Cursed); got != tc.cursed {
+				t.Errorf("cursed = %v, want %v", got, tc.cursed)
+			}
+
+			if obj.ArmorClass < tc.low || obj.ArmorClass > tc.hi {
+				t.Errorf("armor class = %d, want %d..%d",
+					obj.ArmorClass, tc.low, tc.hi)
+			}
+
+			// The armor arm must not fall into init_weapon.
+			if obj.Kind != KindArmor || obj.Which != int(ArmorPlateMail) {
+				t.Errorf("armor became %v which %d", obj.Kind, obj.Which)
+			}
+		})
+	}
+}
+
+// TestCreateRingBonus covers the four bonus rings, C's
+// obj->o_arm = (bless == '-' ? -1 : rnd(2) + 1), where rnd(2)+1 is 1..2.
+// R_ADDHIT is RingDexterity and R_ADDDAM is RingIncreaseDamage; the
+// RingKind iota matches C's R_ numbering index for index.
+func TestCreateRingBonus(t *testing.T) {
+	t.Parallel()
+
+	rings := []RingKind{
+		RingProtection, RingAddStrength, RingDexterity, RingIncreaseDamage,
+	}
+
+	blessings := []struct {
+		name    string
+		bless   byte
+		cursed  bool
+		low, hi int
+	}{
+		{"blessed", '+', false, 1, 2},
+		{"unblessed", 'n', false, 1, 2},
+		{"cursed", '-', true, -1, -1},
+	}
+
+	for _, ring := range rings {
+		for _, tc := range blessings {
+			t.Run(ringTestName(ring, tc.name), func(t *testing.T) {
+				t.Parallel()
+
+				g := mkWizard(t, 25, 1)
+				obj := newObject()
+				obj.Kind = KindRing
+				obj.Which = int(ring)
+
+				setInput(t, g, tc.bless, ' ', Escape)
+				g.createRing(obj)
+
+				if got := obj.Flags.Has(Cursed); got != tc.cursed {
+					t.Errorf("cursed = %v, want %v", got, tc.cursed)
+				}
+
+				if obj.Bonus < tc.low || obj.Bonus > tc.hi {
+					t.Errorf("bonus = %d, want %d..%d",
+						obj.Bonus, tc.low, tc.hi)
+				}
+
+				if used := inputUsed(t, g); used != 1 {
+					t.Errorf("read %d keys, want the 1 blessing answer",
+						used)
+				}
+			})
+		}
+	}
+}
+
+// ringTestName labels a subtest by ring index, the R_ number from rogue.h.
+func ringTestName(ring RingKind, what string) string {
+	return "R_" + strconv.Itoa(int(ring)) + " " + what
+}
+
+// TestCreateRingCursedKindsSkipThePrompt covers C's second case group,
+// "when R_AGGR: case R_TELEPORT: obj->o_flags |= ISCURSED": cursed with
+// no blessing question and no bonus at all.
+func TestCreateRingCursedKindsSkipThePrompt(t *testing.T) {
+	t.Parallel()
+
+	for _, ring := range []RingKind{RingAggravateMonsters, RingTeleportation} {
+		t.Run(ringTestName(ring, "is cursed silently"), func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 26, 1)
+			obj := newObject()
+			obj.Kind = KindRing
+			obj.Which = int(ring)
+
+			setInput(t, g, ' ', Escape)
+			g.createRing(obj)
+
+			if !obj.Flags.Has(Cursed) {
+				t.Error("ring is not cursed")
+			}
+
+			if obj.Bonus != 0 {
+				t.Errorf("bonus = %d, want 0: C sets none here", obj.Bonus)
+			}
+
+			if used := inputUsed(t, g); used != 0 {
+				t.Errorf("read %d keys; C asks nothing for this kind", used)
+			}
+		})
+	}
+}
+
+// TestCreateRingOtherKindsAreLeftAlone is the default arm: every ring
+// outside C's two case groups gets no prompt, no curse and no bonus.
+func TestCreateRingOtherKindsAreLeftAlone(t *testing.T) {
+	t.Parallel()
+
+	others := []RingKind{
+		RingSustainStrength, RingSearching, RingSeeInvisible, RingAdornment,
+		RingRegeneration, RingSlowDigestion, RingStealth, RingMaintainArmor,
+	}
+
+	for _, ring := range others {
+		t.Run(ringTestName(ring, "is untouched"), func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 27, 1)
+			obj := newObject()
+			obj.Kind = KindRing
+			obj.Which = int(ring)
+
+			setInput(t, g, ' ', Escape)
+			g.createRing(obj)
+
+			if obj.Flags.Has(Cursed) {
+				t.Error("ring was cursed; C curses only R_AGGR and R_TELEPORT")
+			}
+
+			if obj.Bonus != 0 {
+				t.Errorf("bonus = %d, want 0", obj.Bonus)
+			}
+
+			if used := inputUsed(t, g); used != 0 {
+				t.Errorf("read %d keys; C asks nothing for this kind", used)
+			}
+		})
+	}
+}
+
+// TestShowMapRendersTheWholeLevel covers wizard.c show_map against a
+// generated level. C clears hw, walks y from 1 to NUMLINES-2 and x across
+// every column writing chat(y,x), then show_win()s it, so the whole map
+// including squares the hero has never seen has to land in the hw window.
+//
+// What show_map does *not* do is mark anything seen: it touches no PLACE
+// at all, in C or here, so there is no F_SEEN assertion to make.
+//
+// The standout attribute is only asserted up to the first non-real
+// square, deliberately. C's two tests are not the same test:
+//
+//	real = flat(y, x);
+//	if (!(real & F_REAL)) wstandout(hw);
+//	...
+//	if (!real) wstandend(hw);        /* whole word, not the bit */
+//
+// new_level.c seeds every square with p_flags = F_REAL, and exactly three
+// sites clear that bit. putpass sets F_PASS first, so a secret passage is
+// left at 0x80. door's secret-door arm clears it on a room-wall exit whose
+// flags are still exactly F_REAL, leaving p_flags == 0. And the trap loop
+// ORs in rnd(NTRAPS), which is 0..7, so the T_DOOR (00) case is zero too
+// until be_trapped ORs F_SEEN in. So C's wstandend does fire, at secret
+// doors and unsprung trapdoors; what it gets wrong is leaking standout
+// forward from a secret passage or a non-trapdoor trap until it reaches
+// one of those — intermittent bands, not a permanently reversed map.
+// game/wizard.go tests isReal both times and highlights the single square.
+// That divergence is reported on issue #7 rather than settled here, so
+// this test asserts only
+// what both agree on: the characters everywhere, standout on every
+// non-real square, and no standout on real squares before the first
+// non-real one.
+func TestShowMapRendersTheWholeLevel(t *testing.T) {
+	t.Parallel()
+
+	// Deep enough that putpass and the trap loop actually fire; both are
+	// gated on the depth, so a level-1 map would have nothing secret.
+	g := mkWizard(t, 31, 20)
+
+	setInput(t, g, ' ')
+	g.showMap()
+
+	hw := g.scr.Hw
+	seenSecret := false
+
+	for y := 1; y < NumLines-1; y++ {
+		for x := range NumCols {
+			c := hw.at(y, x)
+			if c.ch != g.Level.Char(y, x) {
+				t.Fatalf("hw(%d,%d) = %q, want the map char %q",
+					y, x, c.ch, g.Level.Char(y, x))
+			}
+
+			isReal := g.Level.FlagsAt(y, x).Has(FReal)
+			if !isReal && !c.standout {
+				t.Errorf("secret square (%d,%d) was not drawn in standout",
+					y, x)
+			}
+
+			if !seenSecret && isReal && c.standout {
+				t.Errorf("ordinary square (%d,%d) was drawn in standout",
+					y, x)
+			}
+
+			seenSecret = seenSecret || !isReal
+		}
+	}
+
+	if !seenSecret {
+		t.Fatal("generated level has no non-F_REAL squares: the standout " +
+			"half of show_map went untested, pick a deeper level or seed")
+	}
+}
+
+// TestShowMapLoopBoundsMatchC pins the loop bounds. C starts at y = 1
+// and stops before NUMLINES-1, so the top line stays free for show_win's
+// prompt and the status line is never overwritten.
+func TestShowMapLoopBoundsMatchC(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 32, 10)
+
+	// Rows 0 and NUMLINES-1 are blank on a generated level, so a bound
+	// that ran off either end would copy blanks onto blanks and look
+	// identical. Planting a marker in places[] there is what makes the
+	// bound observable at all.
+	const marker = 'Z'
+
+	for x := range NumCols {
+		g.Level.SetChar(0, x, marker)
+		g.Level.SetChar(NumLines-1, x, marker)
+	}
+
+	setInput(t, g, ' ')
+	g.showMap()
+
+	hw := g.scr.Hw
+
+	for x := range NumCols {
+		if got := hw.at(NumLines-1, x).ch; got == marker {
+			t.Fatalf("hw(%d,%d) = %q: the loop ran onto the status line",
+				NumLines-1, x, got)
+		}
+	}
+
+	const want = "---More (level map)---"
+
+	// show_win's prompt covers the start of row 0; past it the row must
+	// still be untouched by the map loop.
+	for x := len(want); x < NumCols; x++ {
+		if got := hw.at(0, x).ch; got == marker {
+			t.Fatalf("hw(0,%d) = %q: the loop ran onto the message line",
+				x, got)
+		}
+	}
+
+	top := make([]byte, 0, len(want))
+
+	for x := range len(want) {
+		top = append(top, hw.at(0, x).ch)
+	}
+
+	if string(top) != want {
+		t.Errorf("top line = %q, want show_win's %q", string(top), want)
+	}
+}
+
+// TestWhatisMarksTheRightTable covers wizard.c whatis's switch: scrolls,
+// potions, sticks and rings each go through set_know on their own
+// per-game table, and the function ends with msg(inv_name(obj, FALSE)),
+// so the reported name is the newly identified one.
+func TestWhatisMarksTheRightTable(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		kind  ObjectKind
+		which int
+		table func(g *RogueGame) []ObjInfo
+	}{
+		{"scroll", KindScroll, int(ScrollEnchantArmor),
+			func(g *RogueGame) []ObjInfo { return g.Items.Scrolls[:] }},
+		{"potion", KindPotion, int(PotionHealing),
+			func(g *RogueGame) []ObjInfo { return g.Items.Potions[:] }},
+		{"wand", KindWand, int(WandLight),
+			func(g *RogueGame) []ObjInfo { return g.Items.Sticks[:] }},
+		{"ring", KindRing, int(RingSearching),
+			func(g *RogueGame) []ObjInfo { return g.Items.Rings[:] }},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 33, 1)
+			obj := newObject()
+			obj.Kind = tc.kind
+			obj.Which = tc.which
+			ch := give(g, obj)
+
+			tbl := tc.table(g)
+			tbl[tc.which].Guess = "a wild guess"
+			before := g.inventoryName(obj, false)
+
+			setInput(t, g, ch, ' ', Escape)
+			g.whatis(false, KindNone)
+
+			if !tbl[tc.which].Know {
+				t.Error("set_know did not mark the table entry known")
+			}
+
+			if tbl[tc.which].Guess != "" {
+				t.Errorf("guess = %q, want it freed", tbl[tc.which].Guess)
+			}
+
+			if !obj.Flags.Has(Known) {
+				t.Error("the object did not get ISKNOW")
+			}
+
+			after := g.inventoryName(obj, false)
+			if after == before {
+				t.Errorf("name is still %q; identifying changed nothing",
+					after)
+			}
+
+			if g.Msgs.Huh != after {
+				t.Errorf("reported %q, want inv_name's %q", g.Msgs.Huh, after)
+			}
+		})
+	}
+}
+
+// TestWhatisIdentifiesOnlyTheChosenEntry is the other half of set_know's
+// contract: one table entry, not a whole table and not its neighbours.
+func TestWhatisIdentifiesOnlyTheChosenEntry(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 34, 1)
+	obj := newObject()
+	obj.Kind = KindScroll
+	obj.Which = int(ScrollEnchantArmor)
+	ch := give(g, obj)
+
+	setInput(t, g, ch, ' ', Escape)
+	g.whatis(false, KindNone)
+
+	for i := range g.Items.Scrolls {
+		if i == obj.Which {
+			continue
+		}
+
+		if g.Items.Scrolls[i].Know {
+			t.Errorf("scroll %d was marked known too", i)
+		}
+	}
+
+	if g.Items.Potions[obj.Which].Know {
+		t.Error("identifying a scroll marked the potion at the same index")
+	}
+}
+
+// TestWhatisWeaponAndArmorOnlySetTheFlag pins C's WEAPON/ARMOR arm, which
+// is "obj->o_flags |= ISKNOW" and no set_know call: knowing this sword is
+// a sword says nothing about the kind, so the per-kind table entry must
+// stay untouched.
+func TestWhatisWeaponAndArmorOnlySetTheFlag(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name  string
+		kind  ObjectKind
+		which int
+		table func(g *RogueGame) []ObjInfo
+	}{
+		{"a mace", KindWeapon, int(WeaponMace),
+			func(g *RogueGame) []ObjInfo { return g.Items.Weapons[:] }},
+		{"plate mail", KindArmor, int(ArmorPlateMail),
+			func(g *RogueGame) []ObjInfo { return g.Items.Armors[:] }},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkWizard(t, 35, 1)
+			obj := newObject()
+			obj.Kind = tc.kind
+			obj.Which = tc.which
+			ch := give(g, obj)
+
+			setInput(t, g, ch, ' ', Escape)
+			g.whatis(false, KindNone)
+
+			if !obj.Flags.Has(Known) {
+				t.Error("the object did not get ISKNOW")
+			}
+
+			if tc.table(g)[tc.which].Know {
+				t.Error("the kind table was marked known; C calls no " +
+					"set_know for weapons or armor")
+			}
+		})
+	}
+}
+
+// TestWhatisEmptyPackSaysSo covers the early return C takes when
+// pack == NULL, before any prompt happens.
+func TestWhatisEmptyPackSaysSo(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 36, 1)
+	g.Player.Pack = nil
+
+	g.whatis(false, KindNone)
+
+	const want = "you don't have anything in your pack to identify"
+
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+
+	if used := inputUsed(t, g); used != 0 {
+		t.Errorf("read %d keys; C returns before get_item", used)
+	}
+}
+
+// TestWhatisInsistRepromptsUntilAMatch drives both re-prompting arms of
+// C's insist loop in one pass: a wrong-kind pick ("you must identify a
+// %s") and then a bare escape with n_objs non-zero ("you must identify
+// something"), before the scroll finally satisfies it. The spaces in the
+// script are the --More-- acknowledgements those two messages force, and
+// without insist neither arm exists — the loop would have returned the
+// potion on the first answer.
+func TestWhatisInsistRepromptsUntilAMatch(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 37, 1)
+
+	pot := newObject()
+	pot.Kind = KindPotion
+	pot.Which = int(PotionHealing)
+	potCh := give(g, pot)
+
+	scr := newObject()
+	scr.Kind = KindScroll
+	scr.Which = int(ScrollEnchantArmor)
+	scrCh := give(g, scr)
+
+	setInput(t, g, potCh, ' ', Escape, ' ', scrCh, ' ', Escape)
+	g.whatis(true, KindScroll)
+
+	if !g.Items.Scrolls[scr.Which].Know {
+		t.Error("the scroll was never identified: the loop gave up early")
+	}
+
+	if g.Items.Potions[pot.Which].Know {
+		t.Error("the wrong-kind potion was identified anyway")
+	}
+
+	if used := inputUsed(t, g); used < 5 {
+		t.Errorf("consumed %d keys, want at least the 5 the two "+
+			"re-prompts need", used)
+	}
+}
+
+// TestWhatisInsistGivesUpWhenNothingMatches covers "if (n_objs == 0)
+// return": asking for the list with nothing appropriate in the pack sets
+// n_objs to 0, and that is the one way out of the insist loop short of
+// picking something. Getting it wrong is not a wrong answer but a hang.
+func TestWhatisInsistGivesUpWhenNothingMatches(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 38, 1)
+	pot := newObject()
+	pot.Kind = KindPotion
+	pot.Which = int(PotionHealing)
+	give(g, pot)
+
+	setInput(t, g, '*', ' ', Escape)
+	g.whatis(true, KindScroll)
+
+	if g.NObjs != 0 {
+		t.Fatalf("n_objs = %d; this test needs the empty-list path", g.NObjs)
+	}
+
+	if g.Items.Potions[pot.Which].Know {
+		t.Error("giving up identified something anyway")
+	}
+}
+
+// TestSetKnowDoesNotLeakAcrossGames is the reason set_know is not just a
+// debug helper: the tables it writes are the per-game discovered lists
+// that drive item naming in ordinary play. They live on RogueGame, and a
+// second game must start ignorant.
+func TestSetKnowDoesNotLeakAcrossGames(t *testing.T) {
+	t.Parallel()
+
+	g1 := mkWizard(t, 39, 1)
+	g2 := mkWizard(t, 40, 1)
+
+	ring := newObject()
+	ring.Kind = KindRing
+	ring.Which = int(RingSearching)
+	g1.Items.Rings[ring.Which].Guess = "a hunch"
+
+	setKnow(ring, g1.Items.Rings[:])
+
+	if !g1.Items.Rings[ring.Which].Know {
+		t.Error("the entry was not marked known")
+	}
+
+	if g1.Items.Rings[ring.Which].Guess != "" {
+		t.Error("the old guess was not freed")
+	}
+
+	if !ring.Flags.Has(Known) {
+		t.Error("the object did not get ISKNOW")
+	}
+
+	if g2.Items.Rings[ring.Which].Know {
+		t.Error("the second game already knows the ring: the discovered " +
+			"tables are shared between games")
+	}
+
+	if g2.Items.Rings[ring.Which].Guess != "" {
+		t.Error("the second game inherited the first game's guess")
+	}
+}
+
+// TestTeleportLandsTheHeroSomewhereLegal covers wizard.c teleport. C
+// picks the spot with find_floor(NULL, &c, FALSE, TRUE) — any room, and
+// monst TRUE, so the square must be steppable and unoccupied — then keeps
+// the room bookkeeping straight (leave_room/enter_room when the room
+// changed, look(TRUE) when it did not) and clears the run state.
+func TestTeleportLandsTheHeroSomewhereLegal(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 41, 3)
+	p := &g.Player
+	from := p.Pos
+	vacated := g.floorAt()
+
+	g.NoMove = 3
+	g.Count = 5
+	g.Running = true
+
+	g.teleport()
+
+	if p.Pos == from {
+		t.Fatal("hero did not move; this seed teleported him onto himself")
+	}
+
+	pp := g.Level.At(p.Pos.Y, p.Pos.X)
+	if !stepOk(pp.Ch) || pp.Monst != nil {
+		t.Errorf("landed on %q with monster %v: find_floor's contract is "+
+			"a steppable, unoccupied square", pp.Ch, pp.Monst != nil)
+	}
+
+	if p.Room != g.roomIn(p.Pos) {
+		t.Error("player room does not match the square he is standing on")
+	}
+
+	if got := g.mvinch(p.Pos.Y, p.Pos.X); got != PlayerCh {
+		t.Errorf("new square shows %q, want the hero %q", got, PlayerCh)
+	}
+
+	if got := g.mvinch(from.Y, from.X); got != vacated {
+		t.Errorf("vacated square shows %q, want floor_at()'s %q",
+			got, vacated)
+	}
+
+	if g.NoMove != 0 || g.Count != 0 || g.Running {
+		t.Errorf("run state left at no_move=%d count=%d running=%v",
+			g.NoMove, g.Count, g.Running)
+	}
+}
+
+// TestTeleportReleasesTheFlytrap covers the tail C spells out: bamfing
+// away while a Flytrap has hold of you clears ISHELD, resets vf_hit and
+// puts the 'F' bestiary entry's damage back to "000x0" — the Flytrap
+// grows its own damage string as it holds on, so leaving it grown would
+// make the next Flytrap of the game start off mid-fight.
+func TestTeleportReleasesTheFlytrap(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 42, 3)
+	p := &g.Player
+	p.Flags.Set(Held)
+	p.VfHit = 4
+	g.Monsters['F'-'A'].Stats.Dmg = dice("3x4")
+
+	g.teleport()
+
+	if p.On(Held) {
+		t.Error("hero is still held after teleporting away")
+	}
+
+	if p.VfHit != 0 {
+		t.Errorf("vf_hit = %d, want 0", p.VfHit)
+	}
+
+	// C strcpy's the literal "000x0"; the port keeps damage parsed, so
+	// the same thing reads back as the single 0x0 attack that string
+	// means rather than as those five characters.
+	dmg := g.Monsters['F'-'A'].Stats.Dmg
+	if len(dmg) != 1 || dmg[0].Count != 0 || dmg[0].Sides != 0 {
+		t.Errorf("flytrap damage = %q, want C's 000x0, one 0x0 attack", dmg)
+	}
+}
+
+// TestTeleportLeavesTheFlytrapAloneWhenFree pins the other side of C's
+// "if (on(player, ISHELD))" guard: an ordinary wizard teleport must not
+// reach into the bestiary and reset a Flytrap that is busy elsewhere.
+func TestTeleportLeavesTheFlytrapAloneWhenFree(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 43, 3)
+	g.Player.VfHit = 2
+	g.Monsters['F'-'A'].Stats.Dmg = dice("3x4")
+
+	g.teleport()
+
+	if g.Player.VfHit != 2 {
+		t.Errorf("vf_hit = %d, want the untouched 2", g.Player.VfHit)
+	}
+
+	if got := g.Monsters['F'-'A'].Stats.Dmg.String(); got != "3x4" {
+		t.Errorf("flytrap damage = %q, want the untouched %q", got, "3x4")
+	}
+}
+
+// TestWizardKitEquipsTheHero covers the CTRL('I') arm of command.c's
+// wizard switch: nine raise_level() calls, a (+1,+1) two-handed sword
+// wielded, and plate mail at o_arm -5 already known and worn.
+func TestWizardKitEquipsTheHero(t *testing.T) {
+	t.Parallel()
+
+	g := mkWizard(t, 44, 1)
+	p := &g.Player
+
+	if p.Stats.Lvl != 1 {
+		t.Fatalf("hero starts at level %d, not 1", p.Stats.Lvl)
+	}
+
+	// raise_level messages queue up --More-- prompts; spaces clear them.
+	setInput(t, g, ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ')
+	g.wizardKit()
+
+	if p.Stats.Lvl != 10 {
+		t.Errorf("level = %d, want 10 after nine raise_level calls",
+			p.Stats.Lvl)
+	}
+
+	checkKitWeapon(t, g)
+	checkKitArmor(t, g)
+}
+
+// checkKitWeapon asserts the sword half of the wizard kit.
+func checkKitWeapon(t *testing.T, g *RogueGame) {
+	t.Helper()
+
+	weap := g.Player.CurWeapon
+	if weap == nil {
+		t.Fatal("no weapon wielded")
+	}
+
+	if weap.Kind != KindWeapon || weap.Which != int(WeaponTwoHandedSword) {
+		t.Errorf("wielding %v which %d, want the two-handed sword",
+			weap.Kind, weap.Which)
+	}
+
+	if weap.HPlus != 1 || weap.DPlus != 1 {
+		t.Errorf("sword is (%+d,%+d), want (+1,+1)", weap.HPlus, weap.DPlus)
+	}
+
+	// init_dam[]'s 2h sword row.
+	if got := weap.Damage.String(); got != "4x4" {
+		t.Errorf("damage = %q, want 4x4", got)
+	}
+
+	if !inPack(g, weap) {
+		t.Error("the sword was never added to the pack")
+	}
+}
+
+// checkKitArmor asserts the plate mail half of the wizard kit.
+func checkKitArmor(t *testing.T, g *RogueGame) {
+	t.Helper()
+
+	armor := g.Player.CurArmor
+	if armor == nil {
+		t.Fatal("no armor worn")
+	}
+
+	if armor.Kind != KindArmor || armor.Which != int(ArmorPlateMail) {
+		t.Errorf("wearing %v which %d, want plate mail",
+			armor.Kind, armor.Which)
+	}
+
+	if armor.ArmorClass != -5 {
+		t.Errorf("armor class = %d, want -5", armor.ArmorClass)
+	}
+
+	if !armor.Flags.Has(Known) {
+		t.Error("the armor is not known")
+	}
+
+	if armor.Count != 1 {
+		t.Errorf("count = %d, want 1", armor.Count)
+	}
+
+	if !inPack(g, armor) {
+		t.Error("the armor was never added to the pack")
+	}
+}
+
+// inPack reports whether obj is filed in the hero's pack.
+func inPack(g *RogueGame, obj *Object) bool {
+	return slices.Contains(g.Player.Pack, obj)
+}

script/lint

@@ -0,0 +1,37 @@
+#!/bin/sh
+# script/lint: lint in docker. golangci-lint is never installed on the host.
+#
+# Traps, each of which yields a green run over an unlinted or partly linted
+# tree:
+#
+# 1. --target and --no-cache-filter must both stay, and $stage must match
+#    the stage name in Dockerfile.lint. BuildKit ignores --no-cache-filter
+#    when no stage matches its argument, serving the lint layer from cache
+#    without a word; --target rejects a name that is not in the file, which
+#    is what makes the single $stage safe.
+#
+# 2. --target checks that the stage exists, not that it is the stage
+#    running golangci-lint, and it halts the build there. Moving the lint
+#    step to another stage, or adding a stage after it, is not caught.
+#
+# 3. .dockerignore decides what reaches the container, and only what
+#    reaches it is linted. Excluding a self-contained Go file drops it from
+#    the lint silently. Never exclude Go sources, go.mod/go.sum or
+#    .golangci.yml.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Must match the stage name in Dockerfile.lint.
+stage=lint
+
+main() {
+    cd "$ROOT"
+    docker build \
+        --target "$stage" \
+        --no-cache-filter="$stage" \
+        --output=type=cacheonly \
+        -f Dockerfile.lint .
+}
+
+main "$@"