Test the wands, staffs and bolt geometry of sticks.c (closes #6)

game/sticks.go was the largest under-tested file in the repo: 534 lines,
23 functions and a single test. It now has two test files, both written
against the C reference (git show origin/c-master:sticks.c) rather than
against the current Go code, so they can catch divergence instead of
recording it.

game/sticks_test.go covers every zap handler that had none — light in a
room and in a corridor, drain-life's too-weak refusal (which returns
before o_charges--), drain's hit-point split and its kill arm,
drainReaches for all three of C's clauses, invisibility and the flytrap
release, polymorph's detach/re-attach dance with the pack, under-
character and delta-clobbering it does on the way, cancellation, both
teleport wands, magic missile, haste/slow in both directions, fix_stick's
damage and charge formulas, and charge_str.

game/bolt_test.go covers fire_bolt: dirch for all eight directions,
boltBounces including the door the hero stands on, an end-to-end flight
asserting the path and resting square, bounces off both wall
orientations, off a corner and diagonally off a wall (which pins C's rule
that a bounce negates both components rather than reflecting), a bounced
bolt striking the hero who fired it, the strike and miss arms, and the
dragon that shrugs off a flame but not a lightning bolt.

The tests read the flight path off the screen: fire_bolt paints its trail
and then paints chat() back over every square it recorded, so on an
otherwise blank screen the non-blank cells are exactly the squares the
bolt occupied, and the walls it bounced off are absent because C undoes
the record before the mvaddch. Determinism comes from a pinRng helper
that searches for a seed whose next draw is the wanted value, and from a
level the tests carve themselves with the generator's own drawRoom. The
hero is fortified wherever a bolt can reach him, since death exits the
process.

No divergence from C was found. Two notes are recorded in the test
comments: fire_bolt's "ch != 'M'" guard is a tautology, because winat is
t_disguise whenever a monster stands there, and the door-under-hero
exception can only be tested by the fact that the run terminates.

TODO.md

@@ -29,11 +29,113 @@ Refactor ground rules:
 
 # Next Step
 
-Broaden unit test coverage where playtesting finds thin spots (rings, sticks,
+Broaden unit test coverage where playtesting finds thin spots — wizard commands
-wizard commands).
+(#7). Rings and sticks, the first two thirds of this step, are done; see the top
+of Completed Steps.
 
 # Completed Steps
 
+- 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
+  — and now has `game/sticks_test.go` (the zap handlers, `drain`, `fix_stick`,
+  `charge_str`) and `game/bolt_test.go` (the `fire_bolt` geometry). Every
+  expectation was read out of `sticks.c` rather than off the Go code; **no
+  divergence from C was found**, and three things worth knowing came out of the
+  reading. (1) **The bolt trail is the test instrument.** `fire_bolt` paints
+  each square with `dirch` and then paints `chat()` back over every square it
+  recorded, so on a screen nothing else has drawn on, the non-blank cells
+  afterwards are exactly the squares the bolt occupied — and the walls it
+  bounced off are absent, because C undoes the record with `c1--` and `break`s
+  before the `mvaddch`. That gives an exact assertion of the path and the
+  resting place without touching game code, and it is why the tests fire from a
+  square that is not the hero's (which is what `chase.c` does for dragon
+  breath): with the hero off the ray the run produces one message and the screen
+  stays readable. (2) **A bounce reverses both components of the direction, not
+  one.** A bolt entering a wall at 45 degrees goes back the way it came instead
+  of reflecting off the surface, so the diagonal-into-a-vertical-wall case is
+  the one that separates C's rule from the plausible wrong one, and it is
+  tested. (3) **The `ch != 'M'` guard on the miss message is a tautology.** `ch`
+  comes from `winat`, and `winat` _is_ `t_disguise` when a monster stands there
+  (`rogue.h` 57), so `ch == 'M'` implies `t_disguise == 'M'` and the arm can
+  never go quiet; it is vestigial from when 'M' was the mimic, and the test pins
+  the port to speaking, so nobody "tidies" it into a real silence. The
+  door-under-hero exception has no assertion of its own because it cannot have
+  one: without it the bolt bounces on the hero's own square forever, recording
+  nothing, and `fire_bolt` never returns — the test for it hangs rather than
+  fails, which the comment on it says. Determinism comes from a `pinRng` helper
+  that searches for a seed whose next draw is the wanted value (running the real
+  `Rng`, never predicting it) and from a level the tests carve themselves
+  through `drawRoom`, since bounce geometry and `drain`'s room/passage/door
+  reach only mean something against known walls and a known passage number. All
+  27 mutations tried against the new tests were caught.
+
+- 2026-08-09 Ring unit-test coverage (`test/rings-coverage`, closes #5): the
+  first third of the standing coverage step. `game/rings.go` had **zero** tests
+  — not one of the 32 in the suite touched wear, removal, hand choice, or the
+  ring contribution to the hunger clock. New `game/rings_test.go` (17 tests, 44
+  subtests) covers `ringOn`, `pickRingHand`, `ringOff`, `gethand`, `ringEat` and
+  `ringNum`, plus the ring arm of `things.c dropcheck` (`dropRing`), which is
+  what actually takes a ring off. Package coverage 53.7% -> 56.2%. `Next Step`
+  narrowed rather than rotated: #6 and #7 are the other two thirds.
+
+    Every expected value is transcribed from `origin/c-master` (`rings.c`,
+    `rogue.h`, `things.c`), never from what the port returns, and the C is
+    quoted in the file. **No divergence from C was found**, which is the result
+    and is worth recording as a negative: `ringEat` is the one function here
+    whose being wrong would be invisible — it feeds `daemons.c`'s hunger clock,
+    so a bad entry is a slow drift in when the hero starves rather than anything
+    a playtest would notice — and it now has all fourteen ring kinds pinned to
+    C's table.
+
+    Three C details the tests were written around. (1) `ring_eat`'s `uses[]`
+    holds negatives, and a negative is **not** a cost: C computes
+    `eat = (rnd(-eat) == 0)`, a one-in-n chance of a single unit. (2) `R_DIGEST`
+    then flips the sign, so slow digestion returns 0 or **-1** and is the only
+    ring that gives food back. (3) `ring_num`'s switch closes with the
+    `otherwise` macro, which `rogue.h` 53 defines as `break;default` — so its
+    four labels fall through to one `sprintf` and every other kind returns `""`
+    from a default arm, not by falling off the end. The `RingKind` iota matches
+    C's `R_` numbering index-for-index, so a `uses[]` index and a `RingKind` are
+    the same number; `R_ADDHIT` is `RingDexterity` and `R_ADDDAM` is
+    `RingIncreaseDamage`.
+
+    The chance rings are checked two ways at once. Each call snapshots the
+    generator, runs `ringEat`, and replays C's own expression from the identical
+    state — which pins the one-in-n denominator, the sign flip, and the fact
+    that exactly one `rnd` call is spent — and a frequency check over 4000
+    trials backs it with a number a human can read. The non-negative entries
+    assert the reverse: the generator must be **untouched**, because C never
+    reaches `rnd` on that path and a stray call there would desynchronise the
+    whole game's RNG stream from C's and cost seed compatibility. That assertion
+    is what caught the one real bug in this work, which was in the test and not
+    the game: `g.Rng` is a pointer, so the first draft's snapshots aliased
+    instead of copying.
+
+    Two shapes worth keeping. Scripted hand answers carry an abort tail (a space
+    for the reprompt's `--More--`, then ESCAPE): without it a port that stopped
+    accepting a key would loop forever on the headless terminal's filler input
+    and the test would die of the 30s timeout instead of failing on its
+    assertion — which is exactly what the first draft did, and it was only
+    visible because the mutation run was inspected rather than trusted. And the
+    "only one hand free" case scripts the _wrong_ hand key deliberately: a port
+    that asked anyway consumes it and lands the ring on the wrong side, so the
+    test fails on a hand rather than on a hang.
+
+    Mutation-proved, 23 mutations, each reverted: breaking `pickRingHand`'s
+    ask/auto/reject arms, `ring_on`'s type guard, `is_current` guard and all
+    three effect arms, `ring_off`'s no-rings message, hand selection and ESCAPE
+    abort, `gethand`'s uppercase keys, ESCAPE and reprompt, `dropRing`'s hand
+    clearing and both effect arms, `dropcheck`'s cursed gate, three `ringUses`
+    entries, the `R_DIGEST` sign flip, the one-in-n roll, the empty-hand zero,
+    and `ring_num`'s `ISKNOW` guard, label set and `RING`-vs-`WEAPON`
+    formatting. Each failed its own test and only its own; stripping all three
+    `ring_on` effect arms failed 3 of 3. All fourteen ring kinds are exercised;
+    the eleven with no wear-time effect in C are documented at the foot of the
+    file as deliberately not given a wear/remove test, with the files their
+    powers actually live in, and `ring_off`'s unreachable "not wearing such a
+    ring" arm is documented as unreachable rather than left looking untested.
+
 - 2026-08-09 Command dispatch audit (`audit/command-switch-coverage`, closes
   #31): checked every case label in C's `command.c` against this port's
   dispatch, and left the audit behind as a standing test

game/bolt_test.go

@@ -0,0 +1,497 @@
+//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
+package game
+
+import (
+	"slices"
+	"testing"
+)
+
+// The bolt geometry of sticks.c fire_bolt, tested on the hand-carved
+// level built by mkCarvedGame in sticks_test.go.
+//
+// Most of these fire from a square that is not the hero's, which is what
+// chase.c does when a dragon breathes (fire_bolt(&th->t_pos, ...)). That
+// keeps the hero off the ray, so the run produces exactly one message
+// and the screen stays readable as a record of where the bolt went — see
+// litCells.
+
+// The three names sticks.c fires a bolt under (do_zap's WS_ELECT,
+// WS_FIRE and WS_COLD arms); fire_bolt prints them and hangs them on the
+// FLAME weapon-table entry.
+const (
+	boltName  = "bolt"
+	flameName = "flame"
+	iceName   = "ice"
+)
+
+// litCells reports every non-blank cell of the map area of the screen.
+//
+// fire_bolt paints its trail with dirch and then erases it by writing
+// back chat() for each square it recorded, so on a screen nothing else
+// has drawn on, the squares left non-blank are exactly the ones the bolt
+// occupied. Squares it bounced off are absent by construction: C undoes
+// the record with c1-- and breaks before the mvaddch, so a wall is
+// neither painted nor erased.
+func litCells(g *RogueGame) []Coord {
+	var out []Coord
+	// Row 0 is the message line, not the map.
+	for y := 1; y < NumLines; y++ {
+		line := g.scr.Std.Line(y)
+		for x := range len(line) {
+			if line[x] != ' ' {
+				out = append(out, Coord{X: x, Y: y})
+			}
+		}
+	}
+
+	return out
+}
+
+// assertErased checks that every square the bolt flew over is showing
+// the map character underneath it again: fire_bolt's closing loop paints
+// chat() back over the whole trail, so a bolt leaves no '/' or '\'
+// behind.
+func assertErased(t *testing.T, g *RogueGame, cells []Coord) {
+	t.Helper()
+
+	for _, c := range cells {
+		got := g.scr.Std.Line(c.Y)[c.X]
+		if want := g.Level.Char(c.Y, c.X); got != want {
+			t.Errorf("square %v shows %q, want the map's %q: the trail "+
+				"was not erased", c, got, want)
+		}
+	}
+}
+
+// TestBoltDirChar covers the dirch switch for all eight directions. C
+// keys it on dir->y + dir->x: the two sums of zero are the '/' pair, the
+// two of magnitude two are the '\' pair, and the four axis directions
+// split on whether y is zero.
+func TestBoltDirChar(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		dir  Coord
+		want byte
+	}{
+		{name: "north", dir: Coord{X: 0, Y: -1}, want: '|'},
+		{name: "south", dir: Coord{X: 0, Y: 1}, want: '|'},
+		{name: "east", dir: Coord{X: 1, Y: 0}, want: '-'},
+		{name: "west", dir: Coord{X: -1, Y: 0}, want: '-'},
+		{name: "north east", dir: Coord{X: 1, Y: -1}, want: '/'},
+		{name: "south west", dir: Coord{X: -1, Y: 1}, want: '/'},
+		{name: "north west", dir: Coord{X: -1, Y: -1}, want: '\\'},
+		{name: "south east", dir: Coord{X: 1, Y: 1}, want: '\\'},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got := boltDirChar(tt.dir); got != tt.want {
+				t.Errorf("boltDirChar(%v) = %q, want %q", tt.dir, got, tt.want)
+			}
+		})
+	}
+}
+
+// TestBoltBounces covers the case labels a bolt reflects off, and the
+// door exception: C jumps to the default arm when the hero is standing
+// on the door, "otherwise it would loop infinitely".
+func TestBoltBounces(t *testing.T) {
+	t.Parallel()
+
+	const heroX, heroY = 5, 5
+
+	tests := []struct {
+		name string
+		ch   byte
+		pos  Coord
+		want bool
+	}{
+		{name: "vertical wall", ch: '|', pos: Coord{X: 6, Y: 5}, want: true},
+		{name: "horizontal wall", ch: '-', pos: Coord{X: 6, Y: 5}, want: true},
+		{name: "solid rock", ch: ' ', pos: Coord{X: 6, Y: 5}, want: true},
+		{name: "door", ch: Door, pos: Coord{X: 6, Y: 5}, want: true},
+		{
+			name: "the door under the hero",
+			ch:   Door,
+			pos:  Coord{X: heroX, Y: heroY},
+			want: false,
+		},
+		{name: "floor", ch: Floor, pos: Coord{X: 6, Y: 5}, want: false},
+		{name: "passage", ch: Passage, pos: Coord{X: 6, Y: 5}, want: false},
+		{name: "staircase", ch: Stairs, pos: Coord{X: 6, Y: 5}, want: false},
+		{name: "a monster", ch: 'Z', pos: Coord{X: 6, Y: 5}, want: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			hero := Coord{X: heroX, Y: heroY}
+			if got := boltBounces(tt.ch, hero, tt.pos); got != tt.want {
+				t.Errorf("boltBounces(%q) = %v, want %v", tt.ch, got, tt.want)
+			}
+		})
+	}
+}
+
+// TestFireBoltFliesStraight is the end-to-end run with nothing in the
+// way: six squares, BOLT_LENGTH of them, and the last one is where the
+// bolt stops.
+func TestFireBoltFliesStraight(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 41)
+	dir := Coord{X: 1, Y: 0}
+
+	g.fireBolt(Coord{X: 2, Y: 2}, &dir, flameName)
+
+	want := []Coord{
+		{X: 3, Y: 2}, {X: 4, Y: 2}, {X: 5, Y: 2},
+		{X: 6, Y: 2}, {X: 7, Y: 2}, {X: 8, Y: 2},
+	}
+
+	got := litCells(g)
+	if !slices.Equal(got, want) {
+		t.Errorf("bolt path = %v, want %v", got, want)
+	}
+
+	assertErased(t, g, got)
+
+	if g.Msgs.Huh != "" {
+		t.Errorf("a bolt that hit nothing said %q", g.Msgs.Huh)
+	}
+
+	if (dir != Coord{X: 1, Y: 0}) {
+		t.Errorf("direction = %v, want it unchanged", dir)
+	}
+}
+
+// TestFireBoltBounces covers the reflection rule in both wall
+// orientations, off a corner, and — the case that separates C's rule
+// from a plausible wrong one — diagonally off a vertical wall. C negates
+// *both* components, so a bolt that came in at 45 degrees goes back the
+// way it came instead of reflecting off the surface.
+// boltBounceCase is one wall-bounce run: where the bolt sets off, which
+// way it goes, the wall it must reflect off, and the squares it must end
+// up having occupied.
+type boltBounceCase struct {
+	name  string
+	start Coord
+	dir   Coord
+	wall  Coord
+	want  []Coord
+}
+
+// run fires the case's bolt and checks its whole flight.
+func (tt boltBounceCase) run(t *testing.T) {
+	t.Helper()
+
+	g := mkCarvedGame(t, 42)
+	dir := tt.dir
+
+	g.fireBolt(tt.start, &dir, flameName)
+
+	got := litCells(g)
+	if !slices.Equal(got, tt.want) {
+		t.Errorf("bolt path = %v, want %v", got, tt.want)
+	}
+
+	assertErased(t, g, got)
+
+	if slices.Contains(got, tt.wall) {
+		t.Errorf("the wall at %v was drawn on; C drops the bounce "+
+			"square from spotpos before the mvaddch", tt.wall)
+	}
+
+	if want := (Coord{X: -tt.dir.X, Y: -tt.dir.Y}); dir != want {
+		t.Errorf("direction = %v after one bounce, want %v", dir, want)
+	}
+
+	if g.Msgs.Huh != "the flame bounces" {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, "the flame bounces")
+	}
+}
+
+func TestFireBoltBounces(t *testing.T) {
+	t.Parallel()
+
+	tests := []boltBounceCase{
+		{
+			name:  "off a vertical wall",
+			start: Coord{X: 3, Y: corridorY},
+			dir:   Coord{X: -1, Y: 0},
+			wall:  Coord{X: 1, Y: corridorY},
+			// Five squares, not six: the square in front of the wall is
+			// flown over twice, and C charges spotpos for both.
+			want: []Coord{
+				{X: 2, Y: 4}, {X: 3, Y: 4}, {X: 4, Y: 4},
+				{X: 5, Y: 4}, {X: 6, Y: 4},
+			},
+		},
+		{
+			name:  "off a horizontal wall",
+			start: Coord{X: 5, Y: 2},
+			dir:   Coord{X: 0, Y: -1},
+			wall:  Coord{X: 5, Y: 1},
+			want: []Coord{
+				{X: 5, Y: 2}, {X: 5, Y: 3}, {X: 5, Y: 4},
+				{X: 5, Y: 5}, {X: 5, Y: 6}, {X: 5, Y: 7},
+			},
+		},
+		{
+			name:  "off a corner",
+			start: Coord{X: 3, Y: 3},
+			dir:   Coord{X: -1, Y: -1},
+			wall:  Coord{X: 1, Y: 1},
+			want: []Coord{
+				{X: 2, Y: 2}, {X: 3, Y: 3}, {X: 4, Y: 4},
+				{X: 5, Y: 5}, {X: 6, Y: 6},
+			},
+		},
+		{
+			name:  "diagonally off a vertical wall",
+			start: Coord{X: 3, Y: corridorY},
+			dir:   Coord{X: -1, Y: -1},
+			wall:  Coord{X: 1, Y: 2},
+			want: []Coord{
+				{X: 2, Y: 3}, {X: 3, Y: 4}, {X: 4, Y: 5},
+				{X: 5, Y: 6}, {X: 6, Y: 7},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			tt.run(t)
+		})
+	}
+}
+
+// TestFireBoltReboundsIntoHero covers the hit_hero/changed pair: a bolt
+// the hero fires starts unable to hit him, and the first bounce flips
+// that, so a wall one square away throws his own bolt back at him.
+func TestFireBoltReboundsIntoHero(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		lvl      int
+		wantMsg  string
+		wantHurt bool
+	}{
+		{
+			name:     "the hero saves",
+			lvl:      saveProofLvl,
+			wantMsg:  "the flame whizzes by you",
+			wantHurt: false,
+		},
+		{
+			name:     "the hero is hit",
+			lvl:      1,
+			wantMsg:  "you are hit by the flame",
+			wantHurt: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 43)
+			placeHero(g, Coord{X: roomAX + 1, Y: corridorY})
+			fortify(g) // a bolt to the face must not exit the test binary
+			g.Player.Stats.Lvl = tt.lvl
+
+			pinRng(t, g, d20, 1) // the lowest save throw there is
+
+			hp := g.Player.Stats.HP
+			dir := Coord{X: -1, Y: 0}
+
+			g.fireBolt(g.Player.Pos, &dir, flameName)
+
+			if g.Msgs.Huh != tt.wantMsg {
+				t.Errorf("message = %q, want %q", g.Msgs.Huh, tt.wantMsg)
+			}
+
+			lost := hp - g.Player.Stats.HP
+			if hurt := lost > 0; hurt != tt.wantHurt {
+				t.Errorf("hero lost %d hit points, want hurt = %v",
+					lost, tt.wantHurt)
+			}
+			// roll(6, 6) is six to thirty-six.
+			if tt.wantHurt && (lost < 6 || lost > 36) {
+				t.Errorf("hero lost %d hit points, want 6..36", lost)
+			}
+		})
+	}
+}
+
+// TestFireBoltFromDoorUnderHeroTerminates covers the guard C wrote the
+// door case for: the hero standing on a door and firing into the wall
+// that door sits in. Without the ce(hero, pos) exception the bolt
+// bounces on his own square forever, never recording a spot and never
+// filling spotpos, and fire_bolt does not return — this test hangs
+// rather than fails if the exception is lost.
+func TestFireBoltFromDoorUnderHeroTerminates(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 44)
+	placeHero(g, Coord{X: doorAX, Y: corridorY})
+	fortify(g)
+
+	pinRng(t, g, d20, 1) // no save: the strike ends the flight
+
+	hp := g.Player.Stats.HP
+	dir := Coord{X: 0, Y: -1} // north, into the wall the door is in
+
+	g.fireBolt(g.Player.Pos, &dir, boltName)
+
+	if g.Msgs.Huh != "you are hit by the bolt" {
+		t.Errorf("message = %q, want the hero to be hit", g.Msgs.Huh)
+	}
+
+	if lost := hp - g.Player.Stats.HP; lost < 6 || lost > 36 {
+		t.Errorf("hero lost %d hit points, want 6..36", lost)
+	}
+}
+
+// TestFireBoltStrikesMonster covers the monster arm both ways, and the
+// dragon's immunity to flame that C spells out in the same breath.
+func TestFireBoltStrikesMonster(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		typ      byte
+		lvl      int
+		bolt     string
+		wantMsg  string
+		wantHurt bool
+	}{
+		{
+			name:     "it fails its save",
+			typ:      'Z',
+			lvl:      1,
+			bolt:     boltName,
+			wantMsg:  "the bolt hits the zombie",
+			wantHurt: true,
+		},
+		{
+			name:     "it saves",
+			typ:      'Z',
+			lvl:      saveProofLvl,
+			bolt:     boltName,
+			wantMsg:  "the bolt whizzes past the zombie",
+			wantHurt: false,
+		},
+		{
+			name:     "a dragon shrugs off a flame",
+			typ:      'D',
+			lvl:      1,
+			bolt:     flameName,
+			wantMsg:  "the flame bounces off the dragon",
+			wantHurt: false,
+		},
+		{
+			name:     "but not a lightning bolt",
+			typ:      'D',
+			lvl:      1,
+			bolt:     boltName,
+			wantMsg:  "the bolt hits the dragon",
+			wantHurt: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 45)
+			placeHero(g, Coord{X: 5, Y: corridorY})
+
+			tp := putMonster(g, tt.typ, Coord{X: 8, Y: corridorY})
+			tp.Stats.Lvl = tt.lvl
+			tp.Stats.HP = 500 // enough to survive 6x6 and stay assertable
+
+			pinRng(t, g, d20, 1) // the lowest save throw there is
+
+			dir := Coord{X: 1, Y: 0}
+			g.fireBolt(g.Player.Pos, &dir, tt.bolt)
+
+			if g.Msgs.Huh != tt.wantMsg {
+				t.Errorf("message = %q, want %q", g.Msgs.Huh, tt.wantMsg)
+			}
+
+			if hurt := tp.Stats.HP < 500; hurt != tt.wantHurt {
+				t.Errorf("monster hit points = %d, want hurt = %v",
+					tp.Stats.HP, tt.wantHurt)
+			}
+		})
+	}
+}
+
+// TestFireBoltMissedMonsterWakesUp covers the rest of the miss arm: a
+// bolt the hero fired sets the monster running (runto) before it says
+// what it whizzed past, and the bolt flies on for its full length.
+func TestFireBoltMissedMonsterWakesUp(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 46)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+
+	tp := putMonster(g, 'Z', Coord{X: 8, Y: corridorY})
+	tp.Stats.Lvl = saveProofLvl
+	tp.Flags.Clear(Awake)
+
+	dir := Coord{X: 1, Y: 0}
+	g.fireBolt(g.Player.Pos, &dir, boltName)
+
+	if !tp.On(Awake) {
+		t.Error("the monster the bolt missed is still asleep")
+	}
+
+	if tp.Dest != &g.Player.Pos {
+		t.Error("the woken monster is not chasing the hero")
+	}
+
+	if tp.OldCh != Floor {
+		t.Errorf("under-character = %q, want %q: fire_bolt records chat() "+
+			"before it resolves the save", tp.OldCh, Floor)
+	}
+}
+
+// TestFireBoltMissSpeaksEvenForAnM pins the "ch != 'M' ||
+// tp->t_disguise == 'M'" guard on C's miss message, which reads as
+// though something looking like an 'M' can be missed silently. It
+// cannot: ch comes from winat, and winat *is* t_disguise whenever a
+// monster stands there (rogue.h 57), so ch == 'M' implies
+// t_disguise == 'M' and the condition is always true. The guard is
+// vestigial — 'M' was the mimic in earlier Rogues — and a port that
+// "tidied" it into a real silence would go quiet where C speaks.
+func TestFireBoltMissSpeaksEvenForAnM(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 47)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+
+	tp := putMonster(g, 'M', Coord{X: 8, Y: corridorY})
+	tp.Stats.Lvl = saveProofLvl
+	tp.Flags.Clear(Awake)
+
+	dir := Coord{X: 1, Y: 0}
+	g.fireBolt(g.Player.Pos, &dir, boltName)
+
+	const want = "the bolt whizzes past the medusa"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+
+	if !tp.On(Awake) {
+		t.Error("the missed medusa was not set running")
+	}
+}

game/rings_test.go

@@ -0,0 +1,751 @@
+//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
+package game
+
+import (
+	"fmt"
+	"math"
+	"testing"
+)
+
+// rings_test.go covers rings.c — ring_on, gethand, ring_off, ring_eat and
+// ring_num — plus the ring arm of things.c dropcheck (dropRing), which is
+// what actually takes a worn ring off.
+//
+// Every expected value below is transcribed from the C reference on the
+// origin/c-master branch (rings.c, rogue.h, things.c), not from what this
+// port happens to return. A test that asserts the current Go behaviour
+// cannot catch the port drifting away from C, which is the only thing
+// these tests exist to do.
+//
+// The C constants in play (rogue.h 122-123 and 275-289):
+//
+//	#define LEFT 0		#define RIGHT 1
+//	R_PROTECT 0   R_ADDSTR 1     R_SUSTSTR 2   R_SEARCH 3
+//	R_SEEINVIS 4  R_NOP 5        R_AGGR 6      R_ADDHIT 7
+//	R_ADDDAM 8    R_REGEN 9      R_DIGEST 10   R_TELEPORT 11
+//	R_STEALTH 12  R_SUSTARM 13   MAXRINGS 14
+//
+// The Go RingKind iota (types.go 303-316) runs in that same order, so a C
+// uses[] index and a Go RingKind are the same number. R_ADDHIT is the
+// dexterity ring (RingDexterity) and R_ADDDAM is RingIncreaseDamage.
+//
+// Nothing here can kill the hero — no ring path in rings.c touches HP,
+// food, or experience — so these tests need no fortify() pinning.
+
+// C message text, verbatim, in the terse/verbose pairs C picks between.
+const (
+	cWearingTwo      = "you already have a ring on each hand"
+	cWearingTwoTerse = "wearing two"
+	cNotARing        = "it would be difficult to wrap that around a finger"
+	cNotARingTerse   = "not a ring"
+	cNoRings         = "you aren't wearing any rings"
+	cNoRingsTerse    = "no rings"
+	cInUse           = "That's already in use"
+	cCursed          = "you can't.  It appears to be cursed"
+)
+
+// ringSeed is the fixed seed every test here runs on: nothing in rings.c
+// depends on the layout, but the RNG stream must be reproducible for the
+// ring_eat chance rolls.
+const ringSeed = 5
+
+// mkRingGame builds a headless game with a clear message line, so that a
+// leftover mpos cannot turn the next msg() into a --More-- that eats the
+// scripted keystrokes.
+func mkRingGame(t *testing.T) *RogueGame {
+	t.Helper()
+
+	g := mkGame(t, ringSeed)
+	g.Msgs.Mpos = 0
+	g.Msgs.Huh = ""
+
+	return g
+}
+
+// handKeys scripts an answer to gethand and appends an abort tail. Without
+// it, a port that stopped accepting the key under test would reprompt
+// forever against the headless terminal's filler input, and the test would
+// die of the 30s timeout instead of failing on its own assertion. The
+// space acknowledges the reprompt's --More-- and the ESCAPE makes gethand
+// give up, so the assertion gets to run and say what actually went wrong.
+// For the same reason, a call that must not prompt at all is scripted with
+// a lone ESCAPE rather than an empty script.
+func handKeys(keys ...byte) []byte {
+	return append(keys, ' ', Escape)
+}
+
+// mkRing builds a ring of the given kind; bonus is C's o_arm.
+func mkRing(kind RingKind, bonus int) *Object {
+	obj := newObject()
+	obj.Kind = KindRing
+	obj.Which = int(kind)
+	obj.Bonus = bonus
+	obj.Count = 1
+
+	return obj
+}
+
+// wear puts a ring straight onto a hand the way a restored save would,
+// bypassing ring_on's prompting and effects.
+func wear(g *RogueGame, hand int, obj *Object) *Object {
+	give(g, obj)
+	g.Player.CurRing[hand] = obj
+
+	return obj
+}
+
+func handDesc(obj *Object) string {
+	if obj == nil {
+		return "empty"
+	}
+
+	return fmt.Sprintf("ring kind %d", obj.RingKind())
+}
+
+// assertHands pins both hands at once, which is what "no state change"
+// means for every rejection path in ring_on.
+func assertHands(t *testing.T, g *RogueGame, left, right *Object) {
+	t.Helper()
+
+	if g.Player.CurRing[Left] != left {
+		t.Errorf("left hand = %s, want %s",
+			handDesc(g.Player.CurRing[Left]), handDesc(left))
+	}
+
+	if g.Player.CurRing[Right] != right {
+		t.Errorf("right hand = %s, want %s",
+			handDesc(g.Player.CurRing[Right]), handDesc(right))
+	}
+}
+
+// TestRingOnUsesTheHandTheHeroPicks covers the first arm of C's ring_on
+// hand choice: "if (cur_ring[LEFT] == NULL && cur_ring[RIGHT] == NULL)
+// { if ((ring = gethand()) < 0) return; }".
+func TestRingOnUsesTheHandTheHeroPicks(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		key  byte
+		hand int
+	}{
+		{"lower l", 'l', Left},
+		{"upper L", 'L', Left},
+		{"lower r", 'r', Right},
+		{"upper R", 'R', Right},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			ring := mkRing(RingAdornment, 0)
+			ch := give(g, ring)
+			setInput(t, g, handKeys(ch, tc.key)...)
+
+			g.ringOn()
+
+			if tc.hand == Left {
+				assertHands(t, g, ring, nil)
+			} else {
+				assertHands(t, g, nil, ring)
+			}
+		})
+	}
+}
+
+// TestRingOnEscapeFromGethandWearsNothing is the "< 0" half of that arm.
+func TestRingOnEscapeFromGethandWearsNothing(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	ring := mkRing(RingAdornment, 0)
+	ch := give(g, ring)
+	setInput(t, g, ch, Escape)
+
+	g.ringOn()
+	assertHands(t, g, nil, nil)
+}
+
+// TestRingOnTakesTheOnlyFreeHandWithoutAsking covers C's second and third
+// arms — "else if (cur_ring[LEFT] == NULL) ring = LEFT" and the RIGHT
+// mirror — which must not prompt. The scripted hand key is deliberately
+// the wrong hand: a port that asked anyway would consume it and put the
+// ring on the occupied side's opposite, failing here instead of hanging.
+func TestRingOnTakesTheOnlyFreeHandWithoutAsking(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name   string
+		worn   int
+		free   int
+		badKey byte
+	}{
+		{"left already worn", Left, Right, 'l'},
+		{"right already worn", Right, Left, 'r'},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			old := wear(g, tc.worn, mkRing(RingStealth, 0))
+			ring := mkRing(RingAdornment, 0)
+			ch := give(g, ring)
+			setInput(t, g, handKeys(ch, tc.badKey)...)
+
+			g.ringOn()
+
+			if g.Player.CurRing[tc.free] != ring {
+				t.Errorf("free hand = %s, want the new ring",
+					handDesc(g.Player.CurRing[tc.free]))
+			}
+
+			if g.Player.CurRing[tc.worn] != old {
+				t.Error("ring_on disturbed the hand that was already worn")
+			}
+		})
+	}
+}
+
+// TestRingOnWithBothHandsFullIsRejected covers C's final else arm. The
+// trailing ESCAPE is scripted so that a port which wrongly fell through
+// to gethand() aborts instead of looping on the exhausted script.
+func TestRingOnWithBothHandsFullIsRejected(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		terse bool
+		want  string
+	}{
+		{"wearing two, verbose", false, cWearingTwo},
+		{"wearing two, terse", true, cWearingTwoTerse},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			g.Options.Terse = tc.terse
+			left := wear(g, Left, mkRing(RingStealth, 0))
+			right := wear(g, Right, mkRing(RingRegeneration, 0))
+			ch := give(g, mkRing(RingAdornment, 0))
+			setInput(t, g, ch, Escape)
+
+			g.ringOn()
+
+			if g.Msgs.Huh != tc.want {
+				t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
+			}
+
+			assertHands(t, g, left, right)
+		})
+	}
+}
+
+// TestRingOnRejectsANonRing covers C's "if (obj->o_type != RING)" guard.
+func TestRingOnRejectsANonRing(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		terse bool
+		want  string
+	}{
+		{"not a ring, verbose", false, cNotARing},
+		{"not a ring, terse", true, cNotARingTerse},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			g.Options.Terse = tc.terse
+			pot := newObject()
+			pot.Kind = KindPotion
+			pot.Which = int(PotionHealing)
+			ch := give(g, pot)
+			setInput(t, g, ch, Escape)
+
+			g.ringOn()
+
+			if g.Msgs.Huh != tc.want {
+				t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
+			}
+
+			assertHands(t, g, nil, nil)
+		})
+	}
+}
+
+// TestRingOnRejectsARingAlreadyWorn covers C's "if (is_current(obj))
+// return", which sits between the type check and the hand choice.
+func TestRingOnRejectsARingAlreadyWorn(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	worn := wear(g, Left, mkRing(RingStealth, 0))
+	setInput(t, g, worn.PackCh, Escape)
+
+	g.ringOn()
+
+	if g.Msgs.Huh != cInUse {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, cInUse)
+	}
+
+	assertHands(t, g, worn, nil)
+}
+
+// TestRingOnAddStrengthAndRingOffReverseEachOther pins the R_ADDSTR arm
+// of ring_on ("case R_ADDSTR: chg_str(obj->o_arm)") against the R_ADDSTR
+// arm of things.c dropcheck ("chg_str(-obj->o_arm)").
+func TestRingOnAddStrengthAndRingOffReverseEachOther(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	ring := mkRing(RingAddStrength, 2)
+	ch := give(g, ring)
+	base := g.Player.Stats.Str
+
+	setInput(t, g, handKeys(ch, 'l')...)
+	g.ringOn()
+
+	if g.Player.Stats.Str != base+2 {
+		t.Errorf("strength after wearing = %d, want %d",
+			g.Player.Stats.Str, base+2)
+	}
+
+	assertHands(t, g, ring, nil)
+
+	// Only the left hand is worn, so ring_off's "else if (cur_ring[RIGHT]
+	// == NULL) ring = LEFT" arm picks it with no prompt.
+	setInput(t, g, Escape)
+	g.ringOff()
+
+	if g.Player.Stats.Str != base {
+		t.Errorf("strength after removal = %d, want %d",
+			g.Player.Stats.Str, base)
+	}
+
+	assertHands(t, g, nil, nil)
+}
+
+// TestRingOnSeeInvisibleAndRingOffUndoIt pins the R_SEEINVIS arms:
+// invis_on() on the way in, unsee() plus extinguish(unsee) on the way
+// out. The pending fuse stands in for a potion of see invisible still
+// running, which is the only way the extinguish is observable.
+func TestRingOnSeeInvisibleAndRingOffUndoIt(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	ring := mkRing(RingSeeInvisible, 0)
+	ch := give(g, ring)
+
+	setInput(t, g, handKeys(ch, 'r')...)
+	g.ringOn()
+
+	if !g.Player.On(CanSeeInvisible) {
+		t.Error("ring of see invisible did not set CanSeeInvisible")
+	}
+
+	g.Fuse(DUnsee, 0, 100, After)
+
+	setInput(t, g, Escape)
+	g.ringOff()
+
+	if g.Player.On(CanSeeInvisible) {
+		t.Error("taking the ring off left CanSeeInvisible set")
+	}
+
+	if g.findSlot(DUnsee) != nil {
+		t.Error("taking the ring off did not extinguish the unsee fuse")
+	}
+}
+
+// TestRingOnAggravateMonstersWakesThem pins the R_AGGR arm, which calls
+// aggravate() — misc.c walks every monster through runTo, setting ISRUN.
+func TestRingOnAggravateMonstersWakesThem(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	tp := spawnAdjacent(g, 'Z')
+	tp.Flags.Clear(Awake)
+
+	ring := mkRing(RingAggravateMonsters, 0)
+	ch := give(g, ring)
+
+	setInput(t, g, handKeys(ch, 'l')...)
+	g.ringOn()
+
+	if !tp.On(Awake) {
+		t.Error("ring of aggravate monsters did not wake the monster")
+	}
+}
+
+// TestGethand covers rings.c gethand end to end. The bad-key case needs
+// the extra space: the reprompt happens with mpos still set from "please
+// type L or R", so endmsg puts up a --More-- that wait_for absorbs.
+func TestGethand(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		input []byte
+		want  int
+	}{
+		{"l", []byte{'l'}, Left},
+		{"L", []byte{'L'}, Left},
+		{"r", []byte{'r'}, Right},
+		{"R", []byte{'R'}, Right},
+		{"escape aborts", []byte{Escape}, -1},
+		{"bad key reprompts", []byte{'x', ' ', 'r'}, Right},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			setInput(t, g, handKeys(tc.input...)...)
+
+			if got := g.gethand(); got != tc.want {
+				t.Errorf("gethand() = %d, want %d", got, tc.want)
+			}
+		})
+	}
+}
+
+// TestRingOffWithNoRingsSaysSo covers ring_off's first arm.
+func TestRingOffWithNoRingsSaysSo(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		terse bool
+		want  string
+	}{
+		{"no rings, verbose", false, cNoRings},
+		{"no rings, terse", true, cNoRingsTerse},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			g.Options.Terse = tc.terse
+			setInput(t, g, Escape)
+
+			g.ringOff()
+
+			if g.Msgs.Huh != tc.want {
+				t.Errorf("message = %q, want %q", g.Msgs.Huh, tc.want)
+			}
+		})
+	}
+}
+
+// TestRingOffWithBothHandsWornAsksWhich covers ring_off's else arm, both
+// the answer and the "(ring = gethand()) < 0" abort.
+func TestRingOffWithBothHandsWornAsksWhich(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		key   byte
+		gone  int
+		stays int
+	}{
+		{"takes off the left", 'l', Left, Right},
+		{"takes off the right", 'r', Right, Left},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkRingGame(t)
+			rings := [2]*Object{
+				Left:  wear(g, Left, mkRing(RingStealth, 0)),
+				Right: wear(g, Right, mkRing(RingRegeneration, 0)),
+			}
+			setInput(t, g, handKeys(tc.key)...)
+
+			g.ringOff()
+
+			if g.Player.CurRing[tc.gone] != nil {
+				t.Errorf("chosen hand still holds %s",
+					handDesc(g.Player.CurRing[tc.gone]))
+			}
+
+			if g.Player.CurRing[tc.stays] != rings[tc.stays] {
+				t.Error("ring_off cleared the hand that was not chosen")
+			}
+		})
+	}
+}
+
+// TestRingOffEscapeKeepsBothRings is the abort half of that arm.
+func TestRingOffEscapeKeepsBothRings(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	left := wear(g, Left, mkRing(RingStealth, 0))
+	right := wear(g, Right, mkRing(RingRegeneration, 0))
+	setInput(t, g, Escape)
+
+	g.ringOff()
+	assertHands(t, g, left, right)
+}
+
+// TestRingOffCursedRingStaysOn covers the dropcheck gate ring_off runs
+// its removal through: things.c returns FALSE for an ISCURSED item after
+// printing this message, and the hand is left alone.
+func TestRingOffCursedRingStaysOn(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	ring := mkRing(RingAddStrength, -1)
+	ring.Flags.Set(Cursed)
+	wear(g, Left, ring)
+	setInput(t, g, Escape)
+
+	g.ringOff()
+
+	if g.Msgs.Huh != cCursed {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, cCursed)
+	}
+
+	assertHands(t, g, ring, nil)
+}
+
+// cRingUse is one entry of the rings.c ring_eat uses[] table.
+type cRingUse struct {
+	kind RingKind
+	name string // the C R_ name, for failure messages
+	uses int
+}
+
+// cRingUses transcribes ring_eat's static uses[] verbatim:
+//
+//	static int uses[] = {
+//	     1,	/* R_PROTECT */		 1,	/* R_ADDSTR */
+//	     1,	/* R_SUSTSTR */		-3,	/* R_SEARCH */
+//	    -5,	/* R_SEEINVIS */	 0,	/* R_NOP */
+//	     0,	/* R_AGGR */		-3,	/* R_ADDHIT */
+//	    -3,	/* R_ADDDAM */		 2,	/* R_REGEN */
+//	    -2,	/* R_DIGEST */		 0,	/* R_TELEPORT */
+//	     1,	/* R_STEALTH */		 1	/* R_SUSTARM */
+//	};
+//
+// A negative entry is not a cost: C computes eat = (rnd(-eat) == 0), a
+// one-in-n chance of a single unit. R_DIGEST then flips the sign, so slow
+// digestion returns 0 or -1 and is the only ring that gives food back.
+func cRingUses() []cRingUse {
+	return []cRingUse{
+		{RingProtection, "R_PROTECT", 1},
+		{RingAddStrength, "R_ADDSTR", 1},
+		{RingSustainStrength, "R_SUSTSTR", 1},
+		{RingSearching, "R_SEARCH", -3},
+		{RingSeeInvisible, "R_SEEINVIS", -5},
+		{RingAdornment, "R_NOP", 0},
+		{RingAggravateMonsters, "R_AGGR", 0},
+		{RingDexterity, "R_ADDHIT", -3},
+		{RingIncreaseDamage, "R_ADDDAM", -3},
+		{RingRegeneration, "R_REGEN", 2},
+		{RingSlowDigestion, "R_DIGEST", -2},
+		{RingTeleportation, "R_TELEPORT", 0},
+		{RingStealth, "R_STEALTH", 1},
+		{RingMaintainArmor, "R_SUSTARM", 1},
+	}
+}
+
+// TestRingEatMatchesTheCUsesTable exercises all fourteen ring kinds, both
+// hands, against the C table above. This is the highest-value assertion in
+// the file: ring_eat feeds the hunger clock through daemons.c, so a wrong
+// entry is a silent, slow divergence from C that no other test would see.
+func TestRingEatMatchesTheCUsesTable(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range cRingUses() {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			for _, hand := range []int{Left, Right} {
+				g := mkRingGame(t)
+				g.Player.CurRing[hand] = mkRing(tc.kind, 0)
+
+				if tc.uses >= 0 {
+					assertFixedRingEat(t, g, hand, tc)
+				} else {
+					assertChanceRingEat(t, g, hand, tc)
+				}
+			}
+		})
+	}
+}
+
+// assertFixedRingEat checks a non-negative uses[] entry. C returns it
+// unchanged and, just as importantly, never reaches rnd() on that path —
+// so the generator must be untouched, or the whole game's RNG stream
+// desynchronises from C's and seed compatibility is gone.
+func assertFixedRingEat(t *testing.T, g *RogueGame, hand int, tc cRingUse) {
+	t.Helper()
+
+	for range 4 {
+		before := *g.Rng
+
+		if got := g.ringEat(hand); got != tc.uses {
+			t.Fatalf("ringEat(%d) for %s = %d, want C uses[] entry %d",
+				hand, tc.name, got, tc.uses)
+		}
+
+		if *g.Rng != before {
+			t.Fatalf("ringEat for %s called rnd(); C only does that for a "+
+				"negative uses[] entry", tc.name)
+		}
+	}
+}
+
+// assertChanceRingEat checks a negative uses[] entry. Each call is replayed
+// against C's own expression from the identical generator state, which pins
+// the one-in-n denominator, the sign flip R_DIGEST gets, and the fact that
+// exactly one rnd() call is spent. The frequency check on top of that
+// fails loudly on a wrong denominator even if the replay were ever
+// weakened to agree with the code by construction.
+func assertChanceRingEat(t *testing.T, g *RogueGame, hand int, tc cRingUse) {
+	t.Helper()
+
+	const trials = 4000
+
+	sign := 1
+	if tc.kind == RingSlowDigestion {
+		sign = -1 // rings.c: if (ring->o_which == R_DIGEST) eat = -eat
+	}
+
+	nonzero := 0
+
+	for range trials {
+		before := *g.Rng
+		got := g.ringEat(hand)
+		after := *g.Rng
+
+		// C: eat = (rnd(-eat) == 0), replayed from the same state.
+		*g.Rng = before
+
+		want := 0
+		if g.Rng.Rnd(-tc.uses) == 0 {
+			want = 1
+		}
+
+		want *= sign
+
+		if *g.Rng != after {
+			t.Fatalf("ringEat for %s did not spend exactly one rnd(%d) call",
+				tc.name, -tc.uses)
+		}
+
+		if got != want {
+			t.Fatalf("ringEat for %s = %d, want %d", tc.name, got, want)
+		}
+
+		if want != 0 {
+			nonzero++
+		}
+	}
+
+	assertOneInN(t, tc, nonzero, trials)
+}
+
+// assertOneInN checks the observed rate against C's 1/n. The tolerance is
+// far tighter than the gap between the three denominators C uses (1/2,
+// 1/3, 1/5) and far wider than the sampling noise at this trial count.
+func assertOneInN(t *testing.T, tc cRingUse, nonzero, trials int) {
+	t.Helper()
+
+	const tolerance = 0.03
+
+	rate := float64(nonzero) / float64(trials)
+	want := 1 / float64(-tc.uses)
+
+	if math.Abs(rate-want) > tolerance {
+		t.Errorf("%s fired %.3f of the time over %d trials, want ~%.3f "+
+			"(C's one-in-%d)", tc.name, rate, trials, want, -tc.uses)
+	}
+}
+
+// TestRingEatEmptyHandIsZero is C's "if ((ring = cur_ring[hand]) == NULL)
+// return 0" — the common case, since the hero usually wears nothing.
+func TestRingEatEmptyHandIsZero(t *testing.T) {
+	t.Parallel()
+
+	g := mkRingGame(t)
+	before := *g.Rng
+
+	for _, hand := range []int{Left, Right} {
+		if got := g.ringEat(hand); got != 0 {
+			t.Errorf("ringEat(%d) with an empty hand = %d, want 0", hand, got)
+		}
+	}
+
+	if *g.Rng != before {
+		t.Error("ringEat on an empty hand consumed RNG")
+	}
+}
+
+// TestRingNum covers rings.c ring_num. Its switch ends in the `otherwise`
+// macro, which rogue.h 53 defines as `break;default` — so the four labels
+// R_PROTECT, R_ADDSTR, R_ADDDAM and R_ADDHIT fall through to a single
+// sprintf(" [%s]", num(o_arm, 0, RING)) and every other kind returns ""
+// from the default arm before the buffer is ever reached. Unknown rings
+// return "" earlier still, from the ISKNOW guard.
+//
+// The game pointer is C's implicit global state; ring_num reads none of
+// it, and the port's signature only carries one to satisfy nameit's
+// prfunc type, so nil is the honest argument here.
+func TestRingNum(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name  string
+		kind  RingKind
+		bonus int
+		known bool
+		want  string
+	}{
+		{"R_PROTECT known", RingProtection, 2, true, " [+2]"},
+		{"R_ADDSTR known", RingAddStrength, 1, true, " [+1]"},
+		{"R_ADDDAM known", RingIncreaseDamage, -1, true, " [-1]"},
+		{"R_ADDHIT known", RingDexterity, 3, true, " [+3]"},
+		{"R_PROTECT cursed", RingProtection, -1, true, " [-1]"},
+		{"R_ADDSTR unknown", RingAddStrength, 2, false, ""},
+		{"R_SEARCH known", RingSearching, 2, true, ""},
+		{"R_DIGEST known", RingSlowDigestion, 2, true, ""},
+		{"R_NOP known", RingAdornment, 0, true, ""},
+		{"R_SUSTARM known", RingMaintainArmor, 2, true, ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			obj := mkRing(tc.kind, tc.bonus)
+			if tc.known {
+				obj.Flags.Set(Known)
+			}
+
+			if got := ringNum(nil, obj); got != tc.want {
+				t.Errorf("ringNum() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+// Coverage of the fourteen ring kinds, for the record:
+//
+// All fourteen are exercised by TestRingEatMatchesTheCUsesTable and ten of
+// them by TestRingNum. Beyond that, only three kinds have a ring_on effect
+// at all — R_ADDSTR, R_SEEINVIS and R_AGGR — and each has its own test
+// above, paired with the dropcheck arm that undoes it. The remaining
+// eleven are deliberately not given a wear/remove test: in C they are
+// inert at wear time, their powers being read from ISWEARING() elsewhere
+// (R_SEARCH and R_TELEPORT in the command.c per-turn tail, R_PROTECT and
+// R_ADDHIT/R_ADDDAM in fight.c, R_REGEN and R_DIGEST in daemons.c,
+// R_SUSTSTR and R_SUSTARM in the drain paths, R_STEALTH in chase.c), so a
+// wear/remove assertion for them would test nothing that rings.c does.
+// Those call sites belong to their own files' tests, not to this one.
+//
+// One branch is intentionally unreachable rather than untested: ring_off's
+// "obj == NULL -> not wearing such a ring" cannot fire, because every arm
+// that reaches it has already established that the chosen hand is worn.
+// The port keeps C's defensive check; there is no state from which to
+// provoke it.

game/sticks_test.go

@@ -0,0 +1,874 @@
+//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
+package game
+
+import (
+	"slices"
+	"strings"
+	"testing"
+)
+
+// The zap and bolt tests need a map they can reason about: real levels
+// put their rooms wherever rooms.c felt like, and sticks.c's geometry —
+// which square a bolt bounces off, which room a drain reaches — only
+// means anything against known walls, a known door, and a known passage
+// number. mkCarvedGame lays out two rooms joined by one corridor, using
+// the generator's own drawRoom so the wall characters (including the
+// '-' corners horiz() paints over vert()'s '|') are what a real level
+// would have:
+//
+//	x:   1                20        40                59
+//	y=1  --------------------        ------------------
+//	     |..................|        |................|
+//	y=4  |..................+########+................|
+//	     |..................|        |................|
+//	y=8  --------------------        ------------------
+const (
+	carvedWidth  = 20                       // room width, both walls included
+	carvedHeight = 8                        // room height, both walls included
+	roomAX       = 1                        // left wall of the west room
+	roomBX       = 40                       // left wall of the east room
+	carvedTopY   = 1                        // top wall of both rooms
+	corridorY    = 4                        // row the corridor and doors run on
+	doorAX       = roomAX + carvedWidth - 1 // east wall of the west room
+	carvedPass   = 2                        // passage number of the corridor
+)
+
+// saveProofLvl makes save_throw(VS_MAGIC) succeed on every roll, so a
+// test can select the "it saved" arm without touching the RNG: C's
+// threshold is 14 + VS_MAGIC - lvl/2, which at level 40 is -3, and
+// roll(1,20) always clears that.
+const saveProofLvl = 40
+
+// mkCarvedGame builds a game on the hand-carved level drawn above, with
+// the hero standing in the south-east corner of the west room — off
+// every row and column the bolt tests fire along.
+func mkCarvedGame(t *testing.T, seed int32) *RogueGame {
+	t.Helper()
+
+	g := New(Params{Seed: seed, Term: &testTerm{}})
+	for i := range g.Level.Places {
+		g.Level.Places[i] = Place{Ch: ' ', Flags: FReal}
+	}
+
+	for i, x := range [...]int{roomAX, roomBX} {
+		rp := &g.Level.Rooms[i]
+		*rp = Room{
+			Pos: Coord{X: x, Y: carvedTopY},
+			Max: Coord{X: carvedWidth, Y: carvedHeight},
+		}
+		g.drawRoom(rp)
+	}
+
+	for i := 2; i < MaxRooms; i++ {
+		g.Level.Rooms[i].Flags = Gone // rooms that are not there
+	}
+
+	for x := doorAX + 1; x < roomBX; x++ {
+		pp := g.Level.At(corridorY, x)
+		pp.Ch = Passage
+		pp.Flags = FReal | FPassage | carvedPass
+	}
+	// Doors carry the passage number in their low bits but not F_PASS,
+	// exactly as passages.c numpass leaves them; roomin therefore reports
+	// the room a door belongs to, and drain's corp lookup finds the
+	// passage behind it.
+	for _, x := range [...]int{doorAX, roomBX} {
+		pp := g.Level.At(corridorY, x)
+		pp.Ch = Door
+		pp.Flags = FReal | carvedPass
+	}
+
+	placeHero(g, Coord{X: roomAX + 17, Y: carvedTopY + 6})
+
+	return g
+}
+
+// placeHero moves the hero and keeps proom, oldpos and oldrp in step,
+// the way move.c and misc.c look do; a --More-- prompt redraws through
+// look, which reads all three.
+func placeHero(g *RogueGame, pos Coord) {
+	g.Player.Pos = pos
+	g.Player.Room = g.roomIn(pos)
+	g.Oldpos = pos
+	g.Oldrp = g.Player.Room
+}
+
+// putMonster drops a monster of the given letter on a carved-level spot.
+func putMonster(g *RogueGame, typ byte, pos Coord) *Monster {
+	tp := &Monster{}
+	g.newMonster(tp, typ, pos)
+
+	return tp
+}
+
+// pinRng rewinds the generator to a state whose next draw is exactly
+// want, so tests can choose a save-throw outcome or a polymorph letter
+// without assuming anything about the generator itself: the wanted
+// value is found by running the real Rng, not by predicting it.
+func pinRng(t *testing.T, g *RogueGame, draw func(*Rng) int, want int) {
+	t.Helper()
+
+	for s := int32(1); s < 100000; s++ {
+		probe := Rng{Seed: s}
+		if draw(&probe) == want {
+			g.Rng.Seed = s
+
+			return
+		}
+	}
+
+	t.Fatalf("no seed found whose next draw is %d", want)
+}
+
+// d20 is the save_throw draw (monsters.c save_throw: roll(1, 20)).
+func d20(r *Rng) int { return r.Roll(1, 20) }
+
+// zapWand builds a wand of the given kind with charges to spare.
+func zapWand(kind WandKind) *Object {
+	obj := newObject()
+	obj.Kind = KindWand
+	obj.Which = int(kind)
+	obj.Charges = 5
+
+	return obj
+}
+
+// TestZapLightLightsTheRoom covers the WS_LIGHT arm: the room loses
+// ISDARK, the wand identifies itself, and the message is C's two-part
+// one (sticks.c 71-89).
+func TestZapLightLightsTheRoom(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 11)
+	g.Player.Room.Flags.Set(Dark)
+
+	g.zapLight(zapWand(WandLight))
+
+	if g.Player.Room.Flags.Has(Dark) {
+		t.Error("the room is still dark after a wand of light")
+	}
+
+	if !g.Items.Sticks[WandLight].Know {
+		t.Error("the wand of light did not identify itself")
+	}
+
+	const want = "the room is lit by a shimmering blue light"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+}
+
+// TestZapLightInPassageFades covers the ISGONE arm: a corridor is not a
+// room, so nothing is lit and the wand still becomes known.
+func TestZapLightInPassageFades(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 12)
+	placeHero(g, Coord{X: doorAX + 3, Y: corridorY})
+	g.Level.Rooms[0].Flags.Set(Dark)
+
+	g.zapLight(zapWand(WandLight))
+
+	if !g.Player.Room.Flags.Has(Gone) {
+		t.Fatal("the hero is not in a passage; the test set-up is wrong")
+	}
+
+	const want = "the corridor glows and then fades"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+
+	if !g.Items.Sticks[WandLight].Know {
+		t.Error("the wand of light did not identify itself in a corridor")
+	}
+
+	if !g.Level.Rooms[0].Flags.Has(Dark) {
+		t.Error("zapping in a corridor lit a room anyway")
+	}
+}
+
+// TestZapDrainLifeTooWeakKeepsCharge covers C's early return: under two
+// hit points the zap is refused, and because C returns before the
+// switch falls out, o_charges-- never runs.
+func TestZapDrainLifeTooWeakKeepsCharge(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 13)
+	g.Player.Stats.HP = 1
+
+	wand := zapWand(WandDrainLife)
+	ch := give(g, wand)
+	setInput(t, g, ch)
+
+	g.doZap()
+
+	const want = "you are too weak to use it"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+
+	if wand.Charges != 5 {
+		t.Errorf("charges = %d, want 5: the refused zap must not cost one",
+			wand.Charges)
+	}
+
+	if g.Player.Stats.HP != 1 {
+		t.Errorf("hit points = %d, want 1", g.Player.Stats.HP)
+	}
+}
+
+// TestDrainSplitsHitPoints covers sticks.c drain: the hero loses half
+// his hit points and the drainees each lose that half divided by their
+// number — monsters out of reach lose nothing.
+func TestDrainSplitsHitPoints(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 14)
+	placeHero(g, Coord{X: 5, Y: 3})
+	g.Player.Stats.HP = 20
+
+	near := [2]*Monster{
+		putMonster(g, 'Z', Coord{X: 7, Y: 3}),
+		putMonster(g, 'Z', Coord{X: 9, Y: 5}),
+	}
+	far := putMonster(g, 'Z', Coord{X: roomBX + 5, Y: 3})
+
+	for _, tp := range []*Monster{near[0], near[1], far} {
+		tp.Stats.HP = 100
+	}
+
+	g.drain()
+
+	if g.Player.Stats.HP != 10 {
+		t.Errorf("hero hit points = %d, want 10", g.Player.Stats.HP)
+	}
+	// 10 hit points spread over two drainees is 5 apiece.
+	for i, tp := range near {
+		if tp.Stats.HP != 95 {
+			t.Errorf("drainee %d hit points = %d, want 95", i, tp.Stats.HP)
+		}
+	}
+
+	if far.Stats.HP != 100 {
+		t.Errorf("the monster in the other room lost %d hit points",
+			100-far.Stats.HP)
+	}
+}
+
+// TestDrainWithNoTargetsCostsNothing covers the cnt == 0 arm, which
+// returns before pstats.s_hpt is halved.
+func TestDrainWithNoTargetsCostsNothing(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 15)
+	placeHero(g, Coord{X: 5, Y: 3})
+	g.Player.Stats.HP = 20
+
+	g.drain()
+
+	const want = "you have a tingling feeling"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+
+	if g.Player.Stats.HP != 20 {
+		t.Errorf("hero hit points = %d, want 20: a drain that found nobody "+
+			"returns before halving them", g.Player.Stats.HP)
+	}
+}
+
+// TestDrainKillsWeakMonster covers the other arm of drain's zot loop: a
+// drainee whose share of the hit points finishes it is killed outright.
+func TestDrainKillsWeakMonster(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 29)
+	placeHero(g, Coord{X: 5, Y: 3})
+	g.Player.Stats.HP = 20
+
+	tp := putMonster(g, 'Z', Coord{X: 7, Y: 3})
+	tp.Stats.HP = 3 // less than the ten points it is about to take
+
+	g.drain()
+
+	if len(g.Level.Monsters) != 0 {
+		t.Error("the drained monster is still on the level")
+	}
+
+	if g.Level.MonsterAt(7, 3) != nil {
+		t.Error("the drained monster is still on the map")
+	}
+
+	const want = "you have defeated the zombie"
+	if g.Msgs.Huh != want {
+		t.Errorf("message = %q, want %q", g.Msgs.Huh, want)
+	}
+}
+
+// TestZapSpeedTogglesHasteAndSlow covers both WS_HASTE_M and WS_SLOW_M
+// in both directions: C cancels the opposite condition when it is
+// already on, and only otherwise applies its own.
+func TestZapSpeedTogglesHasteAndSlow(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name       string
+		kind       WandKind
+		start      CreatureFlags
+		wantHasted bool
+		wantSlowed bool
+		wantTurn   bool
+	}{
+		{name: "haste a monster", kind: WandHasteMonster, wantHasted: true},
+		{
+			name:  "haste cancels a slow",
+			kind:  WandHasteMonster,
+			start: Slowed,
+		},
+		{
+			name:       "slow a monster",
+			kind:       WandSlowMonster,
+			wantSlowed: true,
+			wantTurn:   true,
+		},
+		{
+			name:     "slow cancels a haste",
+			kind:     WandSlowMonster,
+			start:    Hasted,
+			wantTurn: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 30)
+			placeHero(g, Coord{X: 5, Y: corridorY})
+			g.Delta = Coord{X: 1, Y: 0}
+
+			tp := putMonster(g, 'Z', Coord{X: 8, Y: corridorY})
+			tp.Flags.Clear(Hasted | Slowed)
+			tp.Flags.Set(tt.start)
+			tp.Turn = false // only the slow arm sets t_turn
+
+			g.zapSpeed(zapWand(tt.kind))
+
+			if tp.On(Hasted) != tt.wantHasted {
+				t.Errorf("hasted = %v, want %v", tp.On(Hasted), tt.wantHasted)
+			}
+
+			if tp.On(Slowed) != tt.wantSlowed {
+				t.Errorf("slowed = %v, want %v", tp.On(Slowed), tt.wantSlowed)
+			}
+
+			if tp.Turn != tt.wantTurn {
+				t.Errorf("turn = %v, want %v", tp.Turn, tt.wantTurn)
+			}
+
+			if !tp.On(Awake) {
+				t.Error("the zapped monster was not set running")
+			}
+		})
+	}
+}
+
+// TestDrainReaches pins the three-clause drainee test of sticks.c drain
+// one clause at a time: the hero's own room, the passage behind the door
+// he stands on (corp), and — only when he is in a passage — a door of
+// that same passage.
+func TestDrainReaches(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		heroPos  Coord
+		monstPos Coord
+		want     bool
+	}{
+		{
+			name:     "same room",
+			heroPos:  Coord{X: 5, Y: 3},
+			monstPos: Coord{X: 9, Y: 6},
+			want:     true,
+		},
+		{
+			name:     "different room",
+			heroPos:  Coord{X: 5, Y: 3},
+			monstPos: Coord{X: roomBX + 5, Y: 3},
+			want:     false,
+		},
+		{
+			name:     "hero on a door reaches into that passage",
+			heroPos:  Coord{X: doorAX, Y: corridorY},
+			monstPos: Coord{X: doorAX + 4, Y: corridorY},
+			want:     true,
+		},
+		{
+			name:     "hero in the passage reaches its doors",
+			heroPos:  Coord{X: doorAX + 4, Y: corridorY},
+			monstPos: Coord{X: roomBX, Y: corridorY},
+			want:     true,
+		},
+		{
+			name:     "hero in the passage does not reach into a room",
+			heroPos:  Coord{X: doorAX + 4, Y: corridorY},
+			monstPos: Coord{X: roomBX + 5, Y: 3},
+			want:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 16)
+			placeHero(g, tt.heroPos)
+			tp := putMonster(g, 'Z', tt.monstPos)
+
+			var corp *Room
+			if g.Level.Char(tt.heroPos.Y, tt.heroPos.X) == Door {
+				corp = &g.Level.Passages[*g.Level.FlagsAt(
+					tt.heroPos.Y, tt.heroPos.X)&FPassNum]
+			}
+
+			inpass := g.Player.Room.Flags.Has(Gone)
+			if got := g.drainReaches(tp, corp, inpass); got != tt.want {
+				t.Errorf("drainReaches = %v, want %v (inpass=%v corp=%v)",
+					got, tt.want, inpass, corp != nil)
+			}
+		})
+	}
+}
+
+// TestZapInvisibilityHidesMonster covers the WS_INVIS arm.
+func TestZapInvisibilityHidesMonster(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 17)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+	g.Delta = Coord{X: 1, Y: 0}
+
+	tp := putMonster(g, 'Z', Coord{X: 8, Y: corridorY})
+
+	g.zapInvisibility(zapWand(WandInvisibility))
+
+	if !tp.On(Invisible) {
+		t.Error("the zapped monster is still visible")
+	}
+}
+
+// TestZapVictimReleasesFlytrap covers the shared preamble of C's
+// invisibility family: the flytrap holding the hero lets go the moment
+// the ray reaches it, whichever of those wands was zapped.
+func TestZapVictimReleasesFlytrap(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 18)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+	g.Delta = Coord{X: 1, Y: 0}
+	g.Player.Flags.Set(Held)
+
+	tp := putMonster(g, 'F', Coord{X: 6, Y: corridorY})
+
+	g.zapInvisibility(zapWand(WandInvisibility))
+
+	if g.Player.On(Held) {
+		t.Error("the flytrap still holds the hero after the zap")
+	}
+
+	if !tp.On(Invisible) {
+		t.Error("the flytrap was not made invisible")
+	}
+}
+
+// TestZapPolymorphReplacesMonster covers the WS_POLYMORPH arm and its
+// detach/re-attach dance: the creature keeps its identity (the same
+// THING, its pack, and the character it is standing on) but becomes a
+// different monster, listed once and standing where it stood.
+func TestZapPolymorphReplacesMonster(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 19)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+	g.Delta = Coord{X: 1, Y: 0}
+
+	pos := Coord{X: 8, Y: corridorY}
+	tp := putMonster(g, 'K', pos)
+	loot := newObject()
+	loot.Kind = KindPotion
+	tp.Pack = []*Object{loot}
+	tp.OldCh = Stairs // it is standing on the staircase
+
+	const want = 'T'
+
+	pinRng(t, g, func(r *Rng) int { return r.Rnd(26) }, int(want-'A'))
+
+	g.zapPolymorph(zapWand(WandPolymorph))
+
+	if tp.Type != want || tp.Disguise != want {
+		t.Errorf("monster is %q/%q after polymorph, want %q",
+			tp.Type, tp.Disguise, want)
+	}
+
+	if tp.Stats.Lvl != g.Monsters[want-'A'].Stats.Lvl {
+		t.Errorf("level = %d, want the troll's %d: new_monster did not "+
+			"re-roll the stats", tp.Stats.Lvl, g.Monsters[want-'A'].Stats.Lvl)
+	}
+
+	if len(tp.Pack) != 1 || tp.Pack[0] != loot {
+		t.Error("polymorph lost the monster's pack")
+	}
+
+	if tp.OldCh != Stairs {
+		t.Errorf("under-character = %q, want %q", tp.OldCh, Stairs)
+	}
+
+	if g.Level.MonsterAt(pos.Y, pos.X) != tp || tp.Pos != pos {
+		t.Error("the polymorphed monster is not where it stood")
+	}
+
+	if n := len(g.Level.Monsters); n != 1 {
+		t.Errorf("monster list holds %d entries, want 1: detach and "+
+			"new_monster's attach must balance", n)
+	}
+
+	if !g.Items.Sticks[WandPolymorph].Know {
+		t.Error("a polymorph the hero watched did not identify the wand")
+	}
+}
+
+// TestZapPolymorphClobbersDelta pins a C quirk the port keeps: do_zap
+// reuses the global delta as scratch for new_monster's coordinate, so
+// the zap direction is gone by the time the arm returns.
+func TestZapPolymorphClobbersDelta(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 20)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+	g.Delta = Coord{X: 1, Y: 0}
+
+	pos := Coord{X: 8, Y: corridorY}
+	putMonster(g, 'K', pos)
+
+	g.zapPolymorph(zapWand(WandPolymorph))
+
+	if g.Delta != pos {
+		t.Errorf("delta = %v after polymorph, want the victim's %v",
+			g.Delta, pos)
+	}
+}
+
+// TestZapCancellationClearsSpecials covers the WS_CANCEL arm. CANHUH is
+// set on the player and never on a monster in C (only scrolls.c sets
+// it), so the test puts it on by hand: the clear is written to take both
+// bits and the port must keep doing so.
+func TestZapCancellationClearsSpecials(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 21)
+	placeHero(g, Coord{X: 5, Y: corridorY})
+	g.Delta = Coord{X: 1, Y: 0}
+
+	tp := putMonster(g, 'M', Coord{X: 8, Y: corridorY})
+	tp.Flags.Set(Invisible | CanConfuse)
+
+	g.zapCancellation(zapWand(WandCancellation))
+
+	if !tp.On(Cancelled) {
+		t.Error("the monster was not cancelled")
+	}
+
+	if tp.On(Invisible) {
+		t.Error("cancellation left the monster invisible")
+	}
+
+	if tp.On(CanConfuse) {
+		t.Error("cancellation left the monster able to confuse")
+	}
+	// t_disguise = t_type is an identity for every monster a zap ray can
+	// actually stop on: the one disguised kind, the xeroc, looks like an
+	// item, and step_ok is true for item characters, so the ray walks
+	// straight past it. Pinned anyway, because C assigns it.
+	if tp.Disguise != tp.Type {
+		t.Errorf("disguise = %q, want %q", tp.Disguise, tp.Type)
+	}
+}
+
+// TestZapTeleportToPullsMonsterIn covers WS_TELTO: the victim lands on
+// hero + delta, which is the square next to the hero along the ray.
+func TestZapTeleportToPullsMonsterIn(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 22)
+	hero := Coord{X: 5, Y: corridorY}
+	placeHero(g, hero)
+	g.Delta = Coord{X: 1, Y: 0}
+
+	from := Coord{X: 8, Y: corridorY}
+	tp := putMonster(g, 'Z', from)
+
+	g.zapTeleport(zapWand(WandTeleportTo))
+
+	want := Coord{X: hero.X + 1, Y: hero.Y}
+	if tp.Pos != want {
+		t.Errorf("monster at %v after teleport-to, want %v", tp.Pos, want)
+	}
+
+	if g.Level.MonsterAt(want.Y, want.X) != tp {
+		t.Error("the map does not have the monster at its new spot")
+	}
+
+	if g.Level.MonsterAt(from.Y, from.X) != nil {
+		t.Error("the monster is still on the map where it came from")
+	}
+
+	if tp.Dest != &g.Player.Pos {
+		t.Error("the teleported monster is not chasing the hero")
+	}
+
+	if !tp.On(Awake) {
+		t.Error("the teleported monster was not woken")
+	}
+}
+
+// TestZapTeleportAwayMovesMonsterOff covers WS_TELAWAY, whose C loop
+// re-draws until the spot is not the hero's own.
+func TestZapTeleportAwayMovesMonsterOff(t *testing.T) {
+	t.Parallel()
+
+	g := mkCarvedGame(t, 23)
+	hero := Coord{X: 5, Y: corridorY}
+	placeHero(g, hero)
+	g.Delta = Coord{X: 1, Y: 0}
+
+	from := Coord{X: 8, Y: corridorY}
+	tp := putMonster(g, 'Z', from)
+
+	g.zapTeleport(zapWand(WandTeleportAway))
+
+	if tp.Pos == from {
+		t.Error("teleport away did not move the monster")
+	}
+
+	if tp.Pos == hero {
+		t.Error("teleport away dropped the monster onto the hero")
+	}
+
+	if g.Level.Char(tp.Pos.Y, tp.Pos.X) != Floor {
+		t.Errorf("monster landed on %q, want floor",
+			g.Level.Char(tp.Pos.Y, tp.Pos.X))
+	}
+
+	if g.Level.MonsterAt(from.Y, from.X) != nil {
+		t.Error("the monster is still on the map where it came from")
+	}
+}
+
+// vanishMsg is what C says when the missile finds nobody to hit, with
+// the original spelling of "missile" intact (sticks.c 191).
+//
+//nolint:misspell // C's spelling, kept faithfully
+const vanishMsg = "the missle vanishes with a puff of smoke"
+
+// TestZapMagicMissile covers WS_MISSILE both ways: a victim that saves
+// gets C's puff-of-smoke message and no damage, one that does not is
+// hit by a bolt whose o_hplus of 100 cannot miss.
+func TestZapMagicMissile(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		lvl     int
+		wantMsg bool
+	}{
+		{name: "victim saves", lvl: saveProofLvl, wantMsg: true},
+		{name: "victim is hit", lvl: 1, wantMsg: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 24)
+			placeHero(g, Coord{X: 5, Y: corridorY})
+			g.Delta = Coord{X: 1, Y: 0}
+
+			tp := putMonster(g, 'Z', Coord{X: 8, Y: corridorY})
+			tp.Stats.Lvl = tt.lvl
+			tp.Stats.HP = 500
+
+			pinRng(t, g, d20, 1) // the lowest save throw there is
+
+			g.zapMagicMissile(zapWand(WandMagicMissile))
+
+			if got := g.Msgs.Huh == vanishMsg; got != tt.wantMsg {
+				t.Errorf("message = %q, want vanish = %v", g.Msgs.Huh, tt.wantMsg)
+			}
+
+			if hurt := tp.Stats.HP < 500; hurt == tt.wantMsg {
+				t.Errorf("hit points = %d, want damage = %v",
+					tp.Stats.HP, !tt.wantMsg)
+			}
+
+			if !g.Items.Sticks[WandMagicMissile].Know {
+				t.Error("the magic missile wand did not identify itself")
+			}
+		})
+	}
+}
+
+// TestFixStickDamage covers the strcmp against ws_type: a staff swings
+// for 2x3, everything else for 1x1, and both hurl for 1x1.
+func TestFixStickDamage(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		material string
+		want     string
+	}{
+		{material: staffName, want: "2x3"},
+		{material: wandName, want: "1x1"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.material, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 25)
+			g.Items.WandType[WandCold] = tt.material
+
+			cur := newObject()
+			cur.Kind = KindWand
+			cur.Which = int(WandCold)
+			g.fixStick(cur)
+
+			if !slices.Equal(cur.Damage, dice(tt.want)) {
+				t.Errorf("damage = %v, want %v", cur.Damage, tt.want)
+			}
+
+			if !slices.Equal(cur.HurlDmg, dice("1x1")) {
+				t.Errorf("hurl damage = %v, want 1x1", cur.HurlDmg)
+			}
+		})
+	}
+}
+
+// TestFixStickCharges covers the charge switch. C is rnd(10)+10 for the
+// wand of light and rnd(5)+3 for everything else, so both ends of both
+// ranges must show up over enough draws and nothing outside them ever.
+func TestFixStickCharges(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name   string
+		kind   WandKind
+		lo, hi int
+	}{
+		{name: "light", kind: WandLight, lo: 10, hi: 19},
+		{name: "other", kind: WandCold, lo: 3, hi: 7},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 26)
+			lo, hi := 1<<30, -1
+
+			for range 500 {
+				cur := newObject()
+				cur.Kind = KindWand
+				cur.Which = int(tt.kind)
+				g.fixStick(cur)
+				lo = min(lo, cur.Charges)
+				hi = max(hi, cur.Charges)
+			}
+
+			if lo != tt.lo || hi != tt.hi {
+				t.Errorf("charges ranged over %d..%d, want %d..%d",
+					lo, hi, tt.lo, tt.hi)
+			}
+		})
+	}
+}
+
+// TestChargeStr covers sticks.c charge_str: nothing at all until the
+// stick is known, then the terse or verbose bracket.
+func TestChargeStr(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		known bool
+		terse bool
+		want  string
+	}{
+		{name: "unknown", known: false, terse: false, want: ""},
+		{name: "unknown and terse", known: false, terse: true, want: ""},
+		{name: "known", known: true, terse: false, want: " [7 charges]"},
+		{name: "known and terse", known: true, terse: true, want: " [7]"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 27)
+			g.Options.Terse = tt.terse
+
+			obj := zapWand(WandCold)
+			obj.Charges = 7
+
+			if tt.known {
+				obj.Flags.Set(Known)
+			}
+
+			if got := chargeStr(g, obj); got != tt.want {
+				t.Errorf("chargeStr = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+// TestZapBoltNames covers the name each of the three bolt wands fires
+// under (sticks.c 225-231), read back out of the weapon table entry
+// fire_bolt overwrites and out of the bounce message.
+func TestZapBoltNames(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		kind WandKind
+		want string
+	}{
+		{kind: WandLightning, want: boltName},
+		{kind: WandFire, want: flameName},
+		{kind: WandCold, want: iceName},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.want, func(t *testing.T) {
+			t.Parallel()
+
+			g := mkCarvedGame(t, 28)
+			placeHero(g, Coord{X: roomAX + 1, Y: corridorY})
+			g.Player.Stats.Lvl = saveProofLvl // never hurt by the rebound
+			g.Delta = Coord{X: -1, Y: 0}      // straight at the west wall
+
+			g.zapBolt(zapWand(tt.kind))
+
+			if got := g.Items.Weapons[WeaponFlame].Name; got != tt.want {
+				t.Errorf("weapon name = %q, want %q", got, tt.want)
+			}
+
+			if !strings.Contains(g.Msgs.Huh, tt.want) {
+				t.Errorf("message = %q, want it to name the %q",
+					g.Msgs.Huh, tt.want)
+			}
+
+			if !g.Items.Sticks[tt.kind].Know {
+				t.Error("the bolt wand did not identify itself")
+			}
+		})
+	}
+}