Generated-output defaults

Generated diagnostics and command captures belong under the ignored repository scratch namespace, not beside source files. Ask fak for the path instead of inventing a root filename:

$run = fak tree-doctor --scratch-dir fleet-loop
fak loop --json > (Join-Path $run 'dosloop.out')
fak dispatch tick --json > (Join-Path $run 'tick.json')

$cover = fak tree-doctor --scratch-path coverage/unit.cover
fak go test -coverprofile $cover ./internal/...

run="$(fak tree-doctor --scratch-dir fleet-loop)"
fak loop --json >"$run/dosloop.out"
fak dispatch tick --json >"$run/tick.json"

cover="$(fak tree-doctor --scratch-path coverage/unit.cover)"
fak go test -coverprofile "$cover" ./internal/...

Both forms create missing directories, print an absolute path, and refuse absolute paths, .. traversal, or a duplicated _scratch/ prefix. --scratch-path additionally requires a producer directory (for example coverage/unit.cover, not a flat cover.out) so unrelated runs do not recreate a junk drawer inside _scratch.

Use the OS temporary directory instead when an artifact has no value after the command exits. When one producer finishes, remove only its declared top-level namespace and retain the receipt:

fak tree-doctor --reap-scratch fleet-loop --json

--reap-scratch accepts one literal producer name, resolves the absolute _scratch/<producer> target, refuses roots, paths, traversal, globs, and symlink/junction trees, then removes enumerated exact entries bottom-up. Human and JSON receipts name the resolved target, verdict, and removed-entry count; an already-absent producer is an idempotent zero-removal result.

Do not substitute git clean -Xdf -- _scratch/<producer>: because _scratch/ is the ignored ancestor, Git can traverse unrelated ignored siblings despite the descendant pathspec. The explicit whole-namespace maintenance operation remains fak tree-doctor --sweep-scratch --dry-run followed by fak tree-doctor --sweep-scratch; never use it for one producer. The .gitignore rules remain a compatibility backstop for older commands and hand-written redirects; they are not the preferred output path.

Repository Go compiler scratch

An inherited GOTMPDIR under _scratch/go-tmp is maintained through its own bounded path:

fak tree-doctor --go-tmp --json
fak tree-doctor --go-tmp --apply --json

Preview is the default. The doctor inventories immediate children once, caps each recursive walk, and takes one process snapshot for the pass. On Windows it matches each canonical candidate against both Win32_Process.CommandLine and ExecutablePath; supported Unix hosts use their executable and command-line process references. Fresh, referenced, reparse-point, nested-repository, outside-root, unreadable, and process-indeterminate children are kept with a typed JSON reason.

Apply moves only stale unreferenced go-build* directories into a unique OS-temp quarantine, rechecks source and quarantine references, then removes enumerated exact files and directories bottom-up. It uses no recursive wildcard and terminates no process. --go-tmp-root can name the configured root, but the command rejects any root outside the repository _scratch subtree.

Do not use --sweep-scratch for this job. That generic ignored-tree operation sees the whole scratch namespace, including live .dos, dispatch, and producer state; it has no Go process liveness witness. The Go-temp mode is explicit maintenance (and the daily maintenance fold), not a hook installed in every compiler child.

Control prompts and test fixtures

Treat .claude/ as project infrastructure, not an automatic home for every Claude run. Reusable skills, hooks, and generic goal-prompt templates belong there and should be committed. Issue-numbered launch fuel, recovery prompts, transcripts, and per-run state do not: allocate an ignored _scratch/<producer>/ path (or private storage) before launch, then run fak tree-doctor --reap-scratch <producer> when the run closes. fak tree-doctor includes any untracked .claude/ artifact in its durable-WIP inventory and types stale entries park-or-delete so a completed run cannot leave silent residue.

testdata/ is committed test input, not an output directory. A fixture belongs there only when a test reads it and the fixture lands in the same coherent change. Generated candidates, reports, and local corpora go to _scratch/<producer>/ until deliberately promoted. fak tree-doctor types untracked files under any testdata/ directory land-or-delete; this prevents local-only fixtures from masking a clean-clone failure while preserving active peer edits.