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The SIGHUP/SIGTERM handler gob-encoded the live game tree from the signal goroutine while the game goroutine was mid-turn mutating it, and AutoSave removed the save file before encoding — so the failure mode was not a stale save but a deleted one followed by a possibly torn replacement, with a window in which the player had neither. The suite has run under -race since 2026-08-09 and was green because nothing had ever driven the turn loop concurrently with a signal: evidence of untested, not of safe. The handler no longer writes anything. AutoSaveOnSignal posts a request, wakes the input read, and waits up to signalSaveTimeout for the game goroutine to take it; the encode runs on the goroutine that owns the state, at the three points where that goroutine can sit: between turns (command), on waking from a blocked readchar, and while parked in the `!` shell escape (runShellEscape, which now runs the shell on a helper goroutine so a hangup during it still rescues the game). Blocked on input is the case that matters — a dropped connection lands while the player is thinking, so a flag checked only between turns would never be looked at. Terminal.ReadChar therefore returns (byte, bool), with ok false meaning "woken by Interrupt, no key", and term.Tcell posts a tcell.EventInterrupt onto tcell's own event queue to unpark PollEvent. readchar services the request and reads again, so no caller sees it. saveFile writes a temporary file in the save's own directory, fsyncs it and renames it over the target instead of truncating in place, so a save that fails — or never happens because the deadline ran out — leaves the player's previous save whole. The SIGINT/SIGQUIT no-save decision and the single-signal-read ordering guarantee are untouched. pendingSaver reads the game out from under its mutex rather than delegating with it held, because the delegated call now blocks until the save is taken.
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Working notes for agents on this repo. Read this alongside TODO.md (which holds the step queue and workflow) before starting work.
Error handling
Panicking on bad/unexpected errors is allowed and preferred over threading
unlikely error returns through game code — e.g. write-side Close/encode failures
where continuing would mean corrupt state. Return errors where a caller
genuinely handles them (save-file prompts, restore validation). Reserve
deliberate _ = discards for true best-effort paths (scorefile writes,
Terminal.Interrupt's post to a full event queue), always with a comment saying
why.
Signal-time autosave used to be on that list and no longer is (issue #24). It is
best effort in the sense that nothing can be reported to a player whose terminal
is already going away, but the outcome is a value, not a discard: the signal
goroutine calls AutoSaveOnSignal, which hands the save to the game goroutine —
the only one allowed to touch game state — and returns whether it was taken
before the deadline. The game answers between turns (command), while parked
waiting for a key (readchar), and while parked in the ! shell escape
(runShellEscape). saveFile writes a temporary file and renames it over the
target, so a save that fails or never happens leaves the player's previous save
whole; never reintroduce a Remove before the write, and never encode game
state from any goroutine but the game's.
C's exit() calls are not unwound: one game run is one process, so myExit (game/rip.go) restores the terminal via Terminal.Fini and calls os.Exit(0), and Run() never returns. There is nothing to recover — do not write code that expects to regain control after game-over. The testing consequence is that any death (combat, starvation, level drain, freezing) exits the test binary, so tests drive command() directly rather than Run(), and crash-sweep drives pin the hero each turn with the fortify() helper in game/run_test.go.
Linting
The .golangci.yml is byte-identical to the canonical shared config and must not be edited — not even to add an exception. To disable a linter, ask sneak, explaining what the linter does; approved exceptions are recorded as in-code //nolint directives (file-level where a whole file is affected) carrying the approval date, which is what keeps the config canonical. Approved so far: testpackage, exhaustive, and mnd (2026-07-07). paralleltest was approved on 2026-07-06 but the exception is no longer in force — it was fixed instead, with t.Parallel() in all 32 tests. The complexity linters (cyclop, gocognit, nestif) are enabled and clean as of refactor step 7 (2026-07-07): the whole golangci-lint run is 0 issues, so keep it that way — decompose new hot spots rather than reaching for a nolint. Line-level //nolint with a reason is used sparingly for C-faithfulness (e.g. the authentic "missle" message spellings) and provably-safe gosec conversions; each needs a justifying comment.
Faithfulness
Behavior must not change during the idiomatic-Go refactor unless a TODO step says so. The 80x24 seed-compatible gameplay, message text (including original typos), RNG call order, and C quirks (documented in tests like TestHoldScrollGreedyMonsterQuirk) are contract. Doc comments keep their "(file.c func_name)" breadcrumbs.
Debugging
Write real, committed test files with t.Logf output and run them with the make
targets — make test (or make check for the full gate); never raw go test.
The target carries -timeout 30s -race -cover and reruns verbosely on failure,
so a raw invocation silently drops the race detector. No throwaway scratch
scripts. Successful debug probes become regression tests.