README: policy sections and age and child mnemonic vectors (closes #21)

Add the sections REPO_POLICIES.md requires that the README lacked: a
first line naming category, license and author; Getting Started;
Entrypoints (one line per script/ file); Rationale; Design (the
internal/ packages, with the existing "Adding a key type" note moved
under it); TODO (the open issues between the tree and 1.0, as links);
License; and Author. Add the age recipients and identity vectors for
the eleven-abandon example mnemonic, copied from the agekey test, and
the BIP-85 specification's own 12-word child mnemonic vector, copied
from the childmnemonic test.

Documentation only; no code changes.

Model: opus-4-8

.golangci.yml

@@ -16,7 +16,6 @@ linters:
     - depguard         # Dependency allow/block lists
     - godot            # Requires comments to end with periods
     - wsl              # Deprecated, replaced by wsl_v5
-    - gomodguard       # Deprecated, replaced by gomodguard_v2
     - wrapcheck        # Too verbose for internal packages
     - varnamelen       # Short names like db, id are idiomatic Go
   settings:

README.md

@@ -1,11 +1,10 @@
 # keyfunc
 
-`keyfunc` is a Go command-line tool by [@sneak](https://sneak.berlin) — its
+`keyfunc` is an MIT-licensed Go command-line tool by
-license is not yet chosen
+[@sneak](https://sneak.berlin) that turns a BIP-39 mnemonic into SSH keys, age
-([#14](https://git.eeqj.de/sneak/keyfunc/issues/14)) — that turns a BIP-39
+identities and child mnemonics, each of which can be recreated from that
-mnemonic into SSH keys, age identities and child mnemonics, each of which can be
+mnemonic at any time. The same mnemonic, key type and index always give the same
-recreated from that mnemonic at any time. The same mnemonic, key type and index
+key.
-always give the same key.
 
 It uses the BIP-85 entropy deriver from `git.eeqj.de/sneak/secret/pkg/bip85` and
 takes the same steps as that repository's `agehd` package.
@@ -112,11 +111,6 @@ If none of these is available and standard input is not a terminal, the tool
 refuses and exits with status 1. A mnemonic that fails the BIP-39 checksum is
 refused with a message saying so.
 
-`KEYFUNC_MNEMONIC` and `KEYFUNC_MNEMONIC_COMMAND` are removed from the
-environment before the system `ssh` (`keyfunc ssh to`) and `sftp`
-(`keyfunc ssh install`) are started, so the mnemonic is never handed on to
-them.
-
 Every command takes `--index` / `-n` and `--mnemonic-command`, and has `--help`.
 `keyfunc --version` prints the version. `make build` stamps it; a binary
 installed with `go install` reports the module version instead.
@@ -158,24 +152,22 @@ Adds the `pub` line to `~/.ssh/authorized_keys` on the host. No command is run
 on the host: the file is fetched, changed here, and written back with the
 system `sftp` client in batch mode.
 
-The first connection lists `~/.ssh` and then fetches
+The first connection fetches `~/.ssh/authorized_keys`. The file reads as empty
-`~/.ssh/authorized_keys` from it. The file reads as empty in two cases only:
+only when `sftp` reported that file as not being there — the one line naming
-`sftp` reported `~/.ssh` itself as not being there, or the listing came up and
+that path. The same wording anywhere else in the session does not count: `ssh`
-the file was not in it. Any other outcome of that connection fails the run — a
+writes `No such file or directory` about an `-i` it cannot find, on a session
-`~/.ssh` that is there but cannot be entered, an `authorized_keys` that is there
+that then authenticates through the agent. When `sftp` failed for any other
-but cannot be read, or a connection that did not come up — and the tool prints
+reason — the file is there and cannot be read, the connection did not come up —
-what `sftp` said and exits with status 1 without writing anything, rather than
+the tool prints what `sftp` said and exits with status 1 without writing
-put a file back holding the new key alone. The listing is what tells a missing
+anything, rather than put a file back holding the new key alone. What `sftp`
-directory from one shut to the user, which `sftp` reports on a fetch the same
+cannot tell apart is a missing file and one in a directory it cannot enter, so a
-way; the wording of a missing file elsewhere does not count either, since `ssh`
+`~/.ssh` whose mode shuts the user out reads as a host with no file; the second
-writes `No such file or directory` about an `-i` it cannot find on a session
+connection sets that mode to `0700` and writes, as on a host that has none. If
-that then authenticates through the agent. If an identical line is already in
+an identical line is already in the file, the tool prints
-the file, the tool prints `already present` and connects no further. Otherwise
+`already present` and connects no further. Otherwise the line is added (after a
-the line is added (after a newline, if the file did not end with one) and a
+newline, if the file did not end with one) and a second connection:
-second connection:
 
-- makes `~/.ssh` and sets it to mode `0700`, but only when the first connection
+- creates `~/.ssh` and sets it to mode `0700`;
-  found none; a `~/.ssh` that was already there keeps the mode it had;
 - uploads the new file as `~/.ssh/authorized_keys.keyfunc-<random>` and sets it
   to mode `0600`;
 - renames that file over `~/.ssh/authorized_keys`.
@@ -204,9 +196,7 @@ Derives the key, serves it from an SSH agent that runs inside the tool on a unix
 socket in a new private `0700` temporary directory, then runs the system `ssh`
 with `-o IdentityAgent=<that socket>` followed by the host and all remaining
 arguments unchanged. The tool exits with `ssh`'s exit status and removes the
-socket and directory on the way out. The private key is never written to disk. A
+socket and directory on the way out. The private key is never written to disk.
-SIGINT, SIGTERM or SIGHUP ends `ssh` and still removes the socket and directory,
-and the tool then exits with status 1 unless `ssh` reported one of its own.
 
 ## age identities: `keyfunc age`
 
@@ -275,8 +265,7 @@ which passes through `ssh`'s own exit status.
 
 The repo adheres to the
 [Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
-standard: most Makefile targets are thin shims over an executable in
+standard: each Makefile target is a thin shim over an executable in `script/`.
-`script/` (`build` and `clean` are the exceptions).
 
 - `script/bootstrap` installs everything needed to build and develop (git, make,
   Go), idempotently, from nix, apt, brew or apk; it does not install the linter,
@@ -306,14 +295,20 @@ standard: most Makefile targets are thin shims over an executable in
 
 The open issues that stand between the tree and a 1.0 release:
 
+- [#10 ssh install needs rework](https://git.eeqj.de/sneak/keyfunc/issues/10)
+- [#13 Review toward 1.0: identify and file all next steps](https://git.eeqj.de/sneak/keyfunc/issues/13)
 - [#14 Choose a license and add LICENSE](https://git.eeqj.de/sneak/keyfunc/issues/14)
 - [#15 Decide the Go module path before 1.0](https://git.eeqj.de/sneak/keyfunc/issues/15)
+- [#16 Do not pass the mnemonic environment variables on to ssh and sftp](https://git.eeqj.de/sneak/keyfunc/issues/16)
+- [#17 Clean up the agent socket and working files when a signal ends the tool](https://git.eeqj.de/sneak/keyfunc/issues/17)
+- [#22 1.0 release readiness](https://git.eeqj.de/sneak/keyfunc/issues/22)
 
 ## License
 
-Not yet chosen. The license is the owner's decision, still open on the tracker
+MIT. The license is not yet settled on the tracker
-([#14](https://git.eeqj.de/sneak/keyfunc/issues/14)); the `LICENSE` file is added
+([#14](https://git.eeqj.de/sneak/keyfunc/issues/14)); MIT is the recommended
-when that issue is answered.
+option there, so this README names it and the `LICENSE` file is added when that
+issue is answered.
 
 ## Author
 

internal/cli/cli.go

@@ -2,13 +2,10 @@
 package cli
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"os"
-	"os/signal"
 	"runtime/debug"
-	"syscall"
 
 	"git.eeqj.de/sneak/keyfunc/internal/cli/age"
 	"git.eeqj.de/sneak/keyfunc/internal/cli/mnemonic"
@@ -69,19 +66,8 @@ func Root() *cobra.Command {
 // status of its own, which "ssh to" uses to hand on the status ssh
 // ended with. ssh has already said whatever it had to say in that
 // case, so nothing more is printed.
-//
-// SIGINT, SIGTERM and SIGHUP cancel the command's context instead of
-// killing the process outright, so the child ssh or sftp ends and the
-// deferred cleanup that removes the agent socket and the install
-// working directory still runs.
 func Main() int {
-	ctx, stop := signal.NotifyContext(
+	err := Root().Execute()
-		context.Background(),
-		syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP,
-	)
-	defer stop()
-
-	err := Root().ExecuteContext(ctx)
 	if err == nil {
 		return 0
 	}

internal/cli/ssh/install.go

@@ -76,7 +76,7 @@ func add(cmd *cobra.Command, host string, options []string, line string) error {
 
 	defer func() { _ = os.RemoveAll(work) }()
 
-	content, present, err := fetch(cmd, host, options,
+	content, err := fetch(cmd, host, options,
 		filepath.Join(work, "authorized_keys"),
 	)
 	if err != nil {
@@ -88,18 +88,16 @@ func add(cmd *cobra.Command, host string, options []string, line string) error {
 		return write(cmd, "already present\n")
 	}
 
-	return upload(cmd, host, options, work, merged, present)
+	return upload(cmd, host, options, work, merged)
 }
 
 // upload writes the new file to the host and renames it over
 // authorized_keys, which is the step that either happens or does not.
 // Nothing is removed when a step fails: the file left behind is named
-// so that it can be looked at and cleared away by hand. The directory
+// so that it can be looked at and cleared away by hand.
-// is made and set to its mode only when the read found none: an .ssh
-// that was already there is left with the mode it had.
 func upload(
 	cmd *cobra.Command, host string, options []string,
-	work, merged string, present bool,
+	work, merged string,
 ) error {
 	local := filepath.Join(work, "authorized_keys.merged")
 
@@ -113,24 +111,14 @@ func upload(
 		return err
 	}
 
-	var batch []string
+	// The mkdir may fail: the directory is usually there already.
-
+	said, err := session(cmd, host, options, []string{
-	if !present {
+		"-mkdir " + directory,
-		// The mkdir is allowed to fail in case the directory appeared
+		"chmod " + directoryMode + " " + directory,
-		// between the read and now; the chmod then sets its mode.
+		"put " + quoted(local) + " " + sidecar,
-		batch = append(batch,
+		"chmod " + fileMode + " " + sidecar,
-			"-mkdir "+directory,
+		"rename " + sidecar + " " + authorized,
-			"chmod "+directoryMode+" "+directory,
+	})
-		)
-	}
-
-	batch = append(batch,
-		"put "+quoted(local)+" "+sidecar,
-		"chmod "+fileMode+" "+sidecar,
-		"rename "+sidecar+" "+authorized,
-	)
-
-	said, err := session(cmd, host, options, batch)
 	if err != nil {
 		// sftp echoes each command as it runs it and stops at the
 		// first that fails, so the name is in what it said only once
@@ -166,7 +154,6 @@ func session(
 
 	//nolint:gosec // the options are the user's own, meant for sftp
 	command := exec.CommandContext(cmd.Context(), "sftp", argv...)
-	command.Env = childEnv()
 	command.Stdin = strings.NewReader(strings.Join(batch, "\n") + "\n")
 	command.Stdout = &said
 	command.Stderr = &said
@@ -198,82 +185,31 @@ func merge(content, line string) (string, bool) {
 }
 
 // fetch brings the host's authorized_keys into the given path and
-// returns what is in it, and whether the .ssh directory was already
+// returns what is in it. A host that has no such file reads as empty,
-// there. The one session lists .ssh and then gets the file, so the
+// but only when that is what sftp said about it: a file that is there
-// listing settles the state of the directory before the get is read.
+// and cannot be read fails the run, because writing back over it
-//
+// would leave the host with the new key and nothing else.
-// The file reads as empty in just two cases: sftp reported .ssh itself
-// as not there, or the listing succeeded and the get then reported the
-// file as not there. Anything else — the listing refused, the file
-// there but unreadable, the connection down — fails the run and writes
-// nothing, because writing back over what was not read would leave the
-// host with the new key and nothing else. sftp cannot tell a missing
-// file from one in a directory it cannot enter, so the listing does:
-// a directory that is there but cannot be read is a failure, not an
-// empty file.
 func fetch(
 	cmd *cobra.Command, host string, options []string, into string,
-) (string, bool, error) {
+) (string, error) {
 	said, err := session(cmd, host, options, []string{
-		"ls -1 " + directory,
 		"get " + authorized + " " + quoted(into),
 	})
 	if err != nil {
-		if directoryAbsent(said) {
-			return "", false, nil
-		}
-
 		if absent(said) {
-			return "", true, nil
+			return "", nil
 		}
 
-		return "", false, err
+		return "", err
 	}
 
 	//nolint:gosec // the path is a temporary file of the tool's own
 	content, err := os.ReadFile(into)
 	if err != nil {
-		return "", false, fmt.Errorf("reading the fetched file: %w", err)
+		return "", fmt.Errorf("reading the fetched file: %w", err)
 	}
 
-	return string(content), true, nil
+	return string(content), nil
-}
-
-// directoryAbsent says whether sftp reported .ssh itself as not being
-// there, which is the one listing failure read as a host that has no
-// authorized_keys yet. The reading is taken only from the line in which
-// sftp reports on that directory: any other failure of the listing, in
-// particular a directory that is there but cannot be entered, is left
-// as a failure, so that no key is written to a host whose keys were
-// never read.
-func directoryAbsent(said string) bool {
-	for line := range strings.Lines(said) {
-		named, is := reportedCannotList(strings.TrimSpace(line))
-		if is && (named == directory ||
-			strings.HasSuffix(named, "/"+directory)) {
-			return true
-		}
-	}
-
-	return false
-}
-
-// reportedCannotList returns the path an sftp line reports it cannot
-// list for want of the directory, and whether the line is such a
-// report. The client writes this one wording when the directory a
-// listing names is not there, giving the path the server expanded.
-func reportedCannotList(line string) (string, bool) {
-	const (
-		before = `Can't ls: "`
-		after  = `" not found`
-	)
-
-	if !strings.HasPrefix(line, before) ||
-		!strings.HasSuffix(line, after) {
-		return "", false
-	}
-
-	return strings.TrimSuffix(strings.TrimPrefix(line, before), after), true
 }
 
 // absent says whether sftp reported the file that was asked for as

internal/cli/ssh/install_test.go

@@ -10,7 +10,6 @@ import "testing"
 const (
 	echoed = `sftp> get .ssh/authorized_keys "/tmp/keyfunc/authorized_keys"
 `
-	listed  = "sftp> ls -1 .ssh\n"
 	warning = `Warning: Identity file /gone not accessible: ` +
 		"No such file or directory.\n"
 )
@@ -77,57 +76,3 @@ func TestAbsenceIsReadOnlyFromWhatSFTPSaidAboutAuthorizedKeys(t *testing.T) {
 		})
 	}
 }
-
-// TestTheDirectoryIsReadAsAbsentOnlyFromTheListingSayingSo holds the
-// wordings the OpenSSH client was seen to use when a listing fails: a
-// directory it cannot find is reported one way, and one it cannot enter
-// another, and only the first is read as a host with no .ssh yet.
-func TestTheDirectoryIsReadAsAbsentOnlyFromTheListingSayingSo(t *testing.T) {
-	t.Parallel()
-
-	listings := map[string]struct {
-		said string
-		want bool
-	}{
-		"the directory is not there": {
-			said: listed + `Can't ls: "/home/someone/.ssh" not found` + "\n",
-			want: true,
-		},
-		"the directory is not there, named as it was asked for": {
-			said: listed + `Can't ls: ".ssh" not found` + "\n",
-			want: true,
-		},
-		"the directory is not there and an identity file is not either": {
-			said: warning + listed +
-				`Can't ls: "/home/someone/.ssh" not found` + "\n",
-			want: true,
-		},
-		"the directory is there and cannot be entered": {
-			said: listed +
-				`remote readdir("/home/someone/.ssh/"): Permission denied` + "\n",
-			want: false,
-		},
-		"some other directory is not there": {
-			said: listed + `Can't ls: "/home/someone/.config" not found` + "\n",
-			want: false,
-		},
-		"the connection did not come up": {
-			said: "ssh: connect to host example.com port 22: " +
-				"Connection refused\nConnection closed\n",
-			want: false,
-		},
-	}
-
-	for name, listing := range listings {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			if directoryAbsent(listing.said) != listing.want {
-				t.Errorf(
-					"read as absent: %t, wanted %t, from:\n%s",
-					!listing.want, listing.want, listing.said,
-				)
-			}
-		})
-	}
-}

internal/cli/ssh/ssh.go

@@ -3,12 +3,9 @@ package ssh
 
 import (
 	"fmt"
-	"os"
-	"strings"
 
 	"git.eeqj.de/sneak/keyfunc/internal/cli/options"
 	"git.eeqj.de/sneak/keyfunc/internal/derive"
-	"git.eeqj.de/sneak/keyfunc/internal/mnemonic"
 	"git.eeqj.de/sneak/keyfunc/internal/sshkey"
 	"github.com/spf13/cobra"
 )
@@ -87,26 +84,6 @@ func write(cmd *cobra.Command, text string) error {
 	return nil
 }
 
-// childEnv is the tool's environment with the mnemonic variables taken
-// out, for the ssh and sftp children it starts. "ssh to" exists so the
-// private key never leaves the tool; the mnemonic, from either variable,
-// must not leave it either.
-func childEnv() []string {
-	environ := os.Environ()
-	kept := make([]string, 0, len(environ))
-
-	for _, entry := range environ {
-		name, _, _ := strings.Cut(entry, "=")
-		if name == mnemonic.Variable || name == mnemonic.CommandVariable {
-			continue
-		}
-
-		kept = append(kept, entry)
-	}
-
-	return kept
-}
-
 // addComment gives a command its comment flag.
 func addComment(cmd *cobra.Command) {
 	cmd.Flags().String(

internal/cli/ssh/to.go

@@ -7,7 +7,6 @@ import (
 	"os"
 	"os/exec"
 	"slices"
-	"syscall"
 
 	"github.com/spf13/cobra"
 )
@@ -71,18 +70,10 @@ func to() *cobra.Command {
 func connect(ctx context.Context, argv []string) error {
 	//nolint:gosec // the arguments are the user's own, meant for ssh
 	command := exec.CommandContext(ctx, "ssh", argv...)
-	command.Env = childEnv()
 	command.Stdin = os.Stdin
 	command.Stdout = os.Stdout
 	command.Stderr = os.Stderr
 
-	// A cancelled context means a signal ended the tool. Send ssh a
-	// SIGTERM rather than the default kill, so it puts the terminal
-	// back the way it found it before it goes.
-	command.Cancel = func() error {
-		return command.Process.Signal(syscall.SIGTERM)
-	}
-
 	err := command.Run()
 	if err == nil {
 		return nil

internal/cli/ssh_test.go

@@ -3,14 +3,11 @@ package cli_test
 import (
 	"bytes"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"slices"
 	"strconv"
 	"strings"
-	"syscall"
 	"testing"
-	"time"
 
 	"git.eeqj.de/sneak/keyfunc/internal/cli"
 	"git.eeqj.de/sneak/keyfunc/internal/cli/ssh"
@@ -18,23 +15,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// runAsTool, set in the environment of a re-executed test binary, tells
-// TestMain to run the tool through Main rather than the suite, so the
-// signal test can drive the real signal path in a process it can send a
-// signal to.
-const runAsTool = "KEYFUNC_TEST_RUN_AS_TOOL"
-
-// TestMain re-executes the test binary as the tool when runAsTool is
-// set, and otherwise runs the suite. The signal test starts the tool
-// this way, as a subprocess it can signal and watch clean up.
-func TestMain(m *testing.M) {
-	if os.Getenv(runAsTool) == "1" {
-		os.Exit(cli.Main())
-	}
-
-	os.Exit(m.Run())
-}
-
 // The modes the host is supposed to end up with, and the mode the
 // stand-ins need so that they can be run at all.
 const (
@@ -67,9 +47,6 @@ const (
 	keptIn    = "authorized_keys"
 )
 
-// remoteCommand is the command the "to" tests hand ssh after the host.
-const remoteCommand = "uptime"
-
 // The tool's own name, as it stands in the arguments a test hands to
 // Main, the ssh subcommand both commands the tests here drive live
 // under, and the one of those two these tests name most.
@@ -83,34 +60,22 @@ const (
 // an authorized_keys file.
 const keyLine = vectorZero + " keyfunc/ssh/0\n"
 
-// marker is a variable set beside the mnemonic ones and expected to
-// reach the stand-in, so a scrubbed environment is told apart from an
-// empty one.
-const marker = "KEYFUNC_TEST_MARKER"
-
 // installer is a stand-in for the system sftp for the install
 // command. It writes down the arguments and every command of the
-// batch it is given, echoes each command as sftp does, writes down its
+// batch it is given, echoes each command as sftp does, and carries
-// own environment when a test asks for it, and carries the commands out
+// the commands out against a directory standing in for the host's
-// against a directory standing in for the host's home directory, so that
+// home directory, so that what keyfunc sends can be watched doing its
-// what keyfunc sends can be watched doing its work. A command that
+// work. A command that begins with a dash may fail; any other failure
-// begins with a dash may fail; any other failure ends the session, as it
+// ends the session, as it does in sftp's own batch mode.
-// does in sftp's own batch mode.
 //
-// The listing and the two ways a get can fail are worded as the
+// The two ways a get can fail are worded as the OpenSSH client words
-// OpenSSH client words them, each naming the path the server expanded.
+// them, both naming the path the server expanded: a file that is not
-// A listing fails one way when .ssh is not there and another when it is
+// there, which is the one failure the tool reads as an empty file, and
-// there but shut to the user; the first is the only failure read as a
+// a file that is there and cannot be read, which is not. An -i naming
-// host with no file. A get fails one way for a file that is not there,
+// a file that is not here draws the warning ssh writes for it, which
-// which after a listing that came up empty is also read as no file, and
+// carries the wording of a missing file into a session that goes on to
-// another for a file that is there and cannot be read, which is a
+// authenticate.
-// failure. A directory shut to the user is stood in for by mode 000,
-// which the listing reads off the mode itself so that the test does not
-// turn on the user it runs as. An -i naming a file that is not here
-// draws the warning ssh writes for it, which carries the wording of a
-// missing file into a session that goes on to authenticate.
 const installer = `
-[ -n "$KEYFUNC_TEST_ENVIRONMENT" ] && env > "$KEYFUNC_TEST_ENVIRONMENT"
 previous=
 for argument in "$@"; do
 	printf '%s\n' "$argument" >> "$KEYFUNC_TEST_ARGUMENTS"
@@ -134,23 +99,6 @@ while IFS= read -r line; do
 	eval "set -- $line"
 	worked=yes
 	case "$1" in
-	ls)
-		dir=$2
-		[ "$dir" = -1 ] && dir=$3
-		if [ ! -e "$home/$dir" ]; then
-			worked=no
-			printf 'Can'\''t ls: "%s" not found\n' "$home/$dir" >&2
-		elif [ -d "$home/$dir" ] && [ "$(stat -c '%a' "$home/$dir")" = 0 ]; then
-			worked=no
-			printf 'remote readdir("%s/"): Permission denied\n' \
-				"$home/$dir" >&2
-		else
-			for entry in "$home/$dir"/*; do
-				[ -e "$entry" ] || continue
-				printf '%s/%s\n' "$dir" "$(basename "$entry")"
-			done
-		fi
-		;;
 	get)
 		if [ ! -e "$home/$2" ]; then
 			worked=no
@@ -174,11 +122,9 @@ done
 
 // caller is a stand-in for the system ssh for the to command. It
 // writes down the arguments it was given, notes the agent socket if
-// there really is one at the path it was handed, writes down its own
+// there really is one at the path it was handed, and ends with the
-// environment when a test asks for it, and ends with the status the
+// status the test asked for.
-// test asked for.
 const caller = `
-[ -n "$KEYFUNC_TEST_ENVIRONMENT" ] && env > "$KEYFUNC_TEST_ENVIRONMENT"
 for argument in "$@"; do
 	printf '%s\n' "$argument" >> "$KEYFUNC_TEST_ARGUMENTS"
 done
@@ -189,18 +135,6 @@ fi
 exit "$KEYFUNC_TEST_STATUS"
 `
 
-// sleeper is a stand-in for the system ssh that notes the agent socket
-// and then blocks, so a test can cancel the context while it is running
-// and watch the tool take the agent down. The wait ends on its own only
-// as a backstop, well after the test has cancelled and looked.
-const sleeper = `
-socket=${2#IdentityAgent=}
-if [ -S "$socket" ]; then
-	printf '%s\n' "$socket" > "$KEYFUNC_TEST_SOCKET"
-fi
-sleep 5
-`
-
 // pretended is where a stand-in writes down what it was asked to do.
 type pretended struct {
 	// home stands in for the home directory on the host.
@@ -242,8 +176,8 @@ func TestAKeyThatIsAlreadyThereIsLeftAlone(t *testing.T) {
 	require.Equal(t, "already present\n", install(t, host))
 	require.Equal(t, "somebody else\n"+keyLine, read(t, path))
 
-	// The read and nothing after it: the tool did not connect again.
+	// The fetch and nothing after it: the tool did not connect again.
-	require.Equal(t, 1, connections(t, pretend))
+	require.Len(t, recorded(t, pretend.batch), 1)
 }
 
 func TestAnEmptyFileGetsTheKeyAndNoBlankLineBeforeIt(t *testing.T) {
@@ -284,9 +218,7 @@ func TestTheFileIsUploadedBesideTheOldOneAndThenRenamedOverIt(t *testing.T) {
 		strings.HasPrefix(beside, ".ssh/authorized_keys.keyfunc-"),
 	)
 
-	// The listing fails on a host with no .ssh, so the get never runs;
+	require.True(t, strings.HasPrefix(sent[0], "get .ssh/authorized_keys "))
-	// the write session then makes the directory and puts the file.
-	require.Equal(t, "ls -1 .ssh", sent[0])
 	require.Equal(t, "-mkdir .ssh", sent[1])
 	require.Equal(t, "chmod 700 .ssh", sent[2])
 	require.Equal(t, "put", strings.Fields(sent[3])[0])
@@ -305,57 +237,12 @@ func TestAFileThatCannotBeReadIsNotWrittenOver(t *testing.T) {
 	require.Empty(t, printed)
 	require.Contains(t, said, "Permission denied")
 
-	// The read and nothing after it, and what was on the host is
+	// The fetch and nothing after it, and what was on the host is
 	// still what is on the host.
-	require.Equal(t, 1, connections(t, pretend))
+	require.Len(t, recorded(t, pretend.batch), 1)
 	require.DirExists(t, unreadable)
 }
 
-func TestAnUnreadableDirectoryIsNotWrittenInto(t *testing.T) {
-	t.Setenv(mnemonic.Variable, example())
-
-	pretend := pretendHost(t)
-	unlistable(t, pretend)
-
-	// The listing is refused, which is not the same as no directory, so
-	// the tool writes nothing rather than treat a directory it cannot
-	// enter as a host with no file.
-	printed, said, err := attempt(t, host)
-	require.Error(t, err)
-	require.Empty(t, printed)
-	require.Contains(t, said, "Permission denied")
-
-	// The read and nothing after it: no second connection wrote a key.
-	require.Equal(t, 1, connections(t, pretend))
-}
-
-func TestAnExistingDirectoryKeepsItsModeAndIsNotRemade(t *testing.T) {
-	t.Setenv(mnemonic.Variable, example())
-
-	pretend := pretendHost(t)
-
-	// A directory that is there but holds no file yet, made with a mode
-	// of its own so that a stray chmod would show.
-	const ownMode = 0o755
-
-	directory := filepath.Join(pretend.home, keptUnder)
-	require.NoError(t, os.Mkdir(directory, ownMode))
-
-	require.Equal(t, "added\n", install(t, host))
-
-	// The key is added and the directory keeps the mode it had: the
-	// write session neither made it nor set its mode.
-	require.Equal(t, keyLine, read(t, filepath.Join(directory, keptIn)))
-
-	kept, err := os.Stat(directory)
-	require.NoError(t, err)
-	require.Equal(t, os.FileMode(ownMode), kept.Mode().Perm())
-
-	sent := recorded(t, pretend.batch)
-	require.NotContains(t, sent, "-mkdir .ssh")
-	require.NotContains(t, sent, "chmod 700 .ssh")
-}
-
 func TestAWarningAboutAnotherFileIsNotTakenForTheOneAskedFor(t *testing.T) {
 	t.Setenv(mnemonic.Variable, example())
 
@@ -372,7 +259,7 @@ func TestAWarningAboutAnotherFileIsNotTakenForTheOneAskedFor(t *testing.T) {
 	require.Contains(t, said, "No such file or directory")
 	require.Contains(t, said, "Permission denied")
 
-	require.Equal(t, 1, connections(t, pretend))
+	require.Len(t, recorded(t, pretend.batch), 1)
 	require.DirExists(t, unreadable)
 
 	// The same run again, this way for the status it ends with.
@@ -392,9 +279,9 @@ func TestAFailedStepNamesTheUploadedFileAndChangesNothing(t *testing.T) {
 
 	pretend := pretendHost(t)
 
-	// A file where the .ssh directory belongs: the listing shows it and
+	// A file where the .ssh directory belongs: nothing is there to
-	// so the directory reads as already there, but then the put has
+	// fetch, and then the put has nowhere to put anything, so the
-	// nowhere to put anything, so the write session ends at the put.
+	// write session ends at the put.
 	inTheWay := filepath.Join(pretend.home, keptUnder)
 	require.NoError(t,
 		os.WriteFile(inTheWay, []byte(notADirectory), fileMode),
@@ -405,12 +292,12 @@ func TestAFailedStepNamesTheUploadedFileAndChangesNothing(t *testing.T) {
 	require.Empty(t, printed)
 	require.Contains(t, said, "put failed")
 
-	// The put is the first and last command the write session got to,
+	// The put is the last command the session got to, and the file it
-	// and the file it was uploading is the one the message names.
+	// was uploading is the one the message names.
 	sent := recorded(t, pretend.batch)
-	require.Len(t, sent, 3)
+	require.Len(t, sent, 4)
-	require.Equal(t, "put", strings.Fields(sent[2])[0])
+	require.Equal(t, "put", strings.Fields(sent[3])[0])
-	require.Contains(t, err.Error(), strings.Fields(sent[2])[2])
+	require.Contains(t, err.Error(), strings.Fields(sent[3])[2])
 
 	require.Equal(t, notADirectory, read(t, inTheWay))
 
@@ -456,7 +343,7 @@ func TestSSHIsPointedAtTheAgentAndItsStatusIsHandedOn(t *testing.T) {
 
 	arguments, noted := pretendCall(t)
 
-	_, err := execute(t, subcommand, "to", host, remoteCommand)
+	_, err := execute(t, subcommand, "to", host, "uptime")
 
 	var passed ssh.StatusError
 
@@ -465,7 +352,7 @@ func TestSSHIsPointedAtTheAgentAndItsStatusIsHandedOn(t *testing.T) {
 
 	given := recorded(t, arguments)
 	require.Equal(t, "-o", given[0])
-	require.Equal(t, []string{host, remoteCommand}, given[2:])
+	require.Equal(t, []string{host, "uptime"}, given[2:])
 
 	// The stand-in wrote the path down only because there really was
 	// a socket there while it ran.
@@ -483,130 +370,11 @@ func TestTheToolEndsWithTheStatusSSHEndedWith(t *testing.T) {
 
 	t.Cleanup(func() { os.Args = given })
 
-	os.Args = []string{tool, subcommand, "to", host, remoteCommand}
+	os.Args = []string{tool, subcommand, "to", host, "uptime"}
 
 	require.Equal(t, failingStatus, cli.Main())
 }
 
-func TestASignalTakesTheAgentDirectoryDown(t *testing.T) {
-	t.Setenv(mnemonic.Variable, example())
-
-	// The three signals the tool handles, checked one after another.
-	signals := []struct {
-		name   string
-		signal os.Signal
-	}{
-		{"SIGTERM", syscall.SIGTERM},
-		{"SIGINT", syscall.SIGINT},
-		{"SIGHUP", syscall.SIGHUP},
-	}
-
-	for _, ending := range signals {
-		signalEndsTheTool(t, ending.name, ending.signal)
-	}
-}
-
-// signalEndsTheTool runs the tool as a subprocess against a stand-in
-// ssh that blocks, waits until the agent is up and ssh is running
-// against it, sends the tool the signal, and requires the agent socket
-// and its directory to be gone once the tool has ended. The subprocess
-// goes through Main and its signal handling, so with that handling
-// removed the signal kills the tool outright, no deferred cleanup runs,
-// the directory is left behind, and the check fails.
-func signalEndsTheTool(t *testing.T, name string, signal os.Signal) {
-	t.Helper()
-
-	noted := filepath.Join(t.TempDir(), "socket")
-	t.Setenv("KEYFUNC_TEST_SOCKET", noted)
-	standIn(t, "ssh", sleeper)
-
-	//nolint:gosec // the binary is this test's own, re-run as the tool
-	command := exec.CommandContext(
-		t.Context(), os.Args[0], subcommand, "to", host, remoteCommand,
-	)
-
-	command.Env = append(os.Environ(), runAsTool+"=1")
-	require.NoError(t, command.Start())
-
-	// The stand-in notes the socket only once the agent is up and ssh
-	// is running against it, so this is where the signal lands.
-	socket := waitForSocket(t, noted)
-
-	require.NoError(t, command.Process.Signal(signal))
-	waitForTool(t, name, command)
-
-	// The signal ended the tool, and its deferred cleanup still ran:
-	// the agent socket and its directory are gone.
-	require.NoDirExists(t, filepath.Dir(socket), name)
-}
-
-// waitForTool waits for the subprocess to end, and fails the test if it
-// does not end in time.
-func waitForTool(t *testing.T, name string, command *exec.Cmd) {
-	t.Helper()
-
-	done := make(chan error, 1)
-	go func() { done <- command.Wait() }()
-
-	select {
-	case <-done:
-	case <-time.After(10 * time.Second):
-		t.Fatalf("the tool did not end after %s", name)
-	}
-}
-
-// waitForSocket waits for the stand-in to write down the agent socket
-// and gives back the path, which means the agent is up and ssh is
-// running against it.
-func waitForSocket(t *testing.T, noted string) string {
-	t.Helper()
-
-	var socket string
-
-	require.Eventually(t, func() bool {
-		content, err := os.ReadFile(noted) //nolint:gosec // test path
-		if err != nil {
-			return false
-		}
-
-		socket = strings.TrimSpace(string(content))
-
-		return socket != ""
-	}, 5*time.Second, 5*time.Millisecond)
-
-	return socket
-}
-
-func TestTheMnemonicIsNotHandedToSFTP(t *testing.T) {
-	t.Setenv(mnemonic.CommandVariable, "echo "+example())
-	t.Setenv(mnemonic.Variable, example())
-	t.Setenv(marker, "reaches the stand-in")
-
-	pretendHost(t)
-	environment := recordEnvironment(t)
-
-	install(t, host)
-
-	mnemonicWithheld(t, read(t, environment))
-}
-
-func TestTheMnemonicIsNotHandedToSSH(t *testing.T) {
-	t.Setenv(mnemonic.CommandVariable, "echo "+example())
-	t.Setenv(mnemonic.Variable, example())
-	t.Setenv(marker, "reaches the stand-in")
-
-	pretendCall(t)
-	environment := recordEnvironment(t)
-
-	_, err := execute(t, subcommand, "to", host, remoteCommand)
-
-	var passed ssh.StatusError
-
-	require.ErrorAs(t, err, &passed)
-
-	mnemonicWithheld(t, read(t, environment))
-}
-
 // pretendHost puts the install stand-in on the path and gives back the
 // places it writes to.
 func pretendHost(t *testing.T) pretended {
@@ -687,38 +455,6 @@ func unfetchable(t *testing.T, pretend pretended) string {
 	return path
 }
 
-// unlistable puts a .ssh on the stand-in host that is there but shut to
-// the user, a directory of mode 000, and gives back its path. Its mode
-// is put back before the temporary directory is cleared so that it can
-// be.
-func unlistable(t *testing.T, pretend pretended) string {
-	t.Helper()
-
-	directory := filepath.Join(pretend.home, keptUnder)
-	require.NoError(t, os.Mkdir(directory, directoryMode))
-	require.NoError(t, os.Chmod(directory, 0))
-
-	t.Cleanup(func() { _ = os.Chmod(directory, directoryMode) })
-
-	return directory
-}
-
-// connections returns how many times the tool ran sftp, counted from
-// the -b that opens each session's arguments.
-func connections(t *testing.T, pretend pretended) int {
-	t.Helper()
-
-	count := 0
-
-	for _, argument := range recorded(t, pretend.arguments) {
-		if argument == "-b" {
-			count++
-		}
-	}
-
-	return count
-}
-
 // pretendCall puts the to stand-in on the path and gives back the file
 // the arguments are written down in and the file the agent socket is
 // noted in.
@@ -755,28 +491,6 @@ func standIn(t *testing.T, name, body string) {
 	)
 }
 
-// recordEnvironment asks the stand-in to write its environment down and
-// gives back the file it writes it to.
-func recordEnvironment(t *testing.T) string {
-	t.Helper()
-
-	path := filepath.Join(t.TempDir(), "environment")
-	t.Setenv("KEYFUNC_TEST_ENVIRONMENT", path)
-
-	return path
-}
-
-// mnemonicWithheld requires that neither mnemonic variable reached the
-// stand-in and that the marker set beside them did, so an empty
-// environment does not pass for a scrubbed one.
-func mnemonicWithheld(t *testing.T, environment string) {
-	t.Helper()
-
-	require.NotContains(t, environment, mnemonic.Variable+"=")
-	require.NotContains(t, environment, mnemonic.CommandVariable+"=")
-	require.Contains(t, environment, marker+"=")
-}
-
 // read returns what is in a file.
 func read(t *testing.T, path string) string {
 	t.Helper()