Gate prune's local-cleanup output on --json, and make make build build (closes #108)

Closes #110.

CleanupLocalSnapshots wrote three prose lines to stdout with no --json
awareness, covering every branch, so `vaultik prune --json | jq` failed
on any input. -q never helped either: printlnStdout and stdoutf write
straight to v.Stdout and never consult v.UI, which is what SetQuiet
affects. It now takes *PruneOptions, symmetric with its sibling phase
PruneBlobs, and gates all three writes.

Threading opts.JSON was chosen over moving the lines to log.Info,
because internal/log/log.go defaults the level to Warn: log.Info would
not have relocated them to stderr, it would have deleted them from a
plain `vaultik prune`, and "Removing stale local record" narrates the
deletion of local index rows. The stale-record count is deliberately not
added to PruneBlobsResult - every field there is blob-scoped and produced
by the phase that runs after this reconciliation, so adding it would
change a published --json schema as a side effect of a stream fix.

Note for anyone reading the --json contract: under --json the
stale-record removal now produces no signal in either stream. stdout is
correctly gated, stderr is level-pinned to Warn because --json sets
Quiet, and the count is not in the document. That is inherited behaviour
- PruneBlobs' own log.Info calls are equally invisible under --json - not
something this change introduced, and it is tracked separately.

make build exited 0 and produced nothing: .PHONY listed build with no
build: rule, and a phony target with no prerequisites and no recipe is
considered already satisfied, which turns what would be a hard error into
a silent success. In a repo where `make build` is the documented way to
build, a caller checking the exit code concluded the build worked. Now
`build: vaultik`, verified in both directions - a clean build produces
the binary, a deliberately broken one exits non-zero and produces none.

All 19 .PHONY names were audited; build was the only one lacking a rule.
TestPhonyTargetsAllHaveRules keeps that true for names added later, so
the class is closed rather than the instance.

Makefile

@@ -66,7 +66,18 @@ lint:
 lint-fix:
 	@script/lint-fix
 
-# Build binary.
+# Build binary. `build` is the name the org convention reaches for and
+# the one a caller checks the exit code of; `vaultik` is the file rule
+# that does the work, so an unchanged tree still short-circuits.
+#
+# This alias is not decorative. `build` was listed in .PHONY with no
+# rule, and a phony target with no prerequisites and no recipe is
+# already satisfied: `make build` printed "Nothing to be done" and
+# exited 0 without producing a binary (issue #110). Every name in
+# .PHONY needs a rule for that reason; TestPhonyTargetsAllHaveRules in
+# cmd/vaultik keeps it that way.
+build: vaultik
+
 vaultik: internal/*/*.go cmd/vaultik/*.go
 	go build -ldflags "$(LDFLAGS)" -o $@ ./cmd/vaultik
 

README.md

@@ -139,10 +139,13 @@ Format follows the stream: when stderr is a terminal the records are
 colorized one-liners, and when it is redirected or piped they are
 JSON, one object per line.
 
-The startup banner is the other thing that writes to stdout, and
-`--json` suppresses it, as `--quiet` and `--cron` do. So
-`vaultik snapshot list --json | jq .` works on its own, with no
-additional flag to quiet the banner first.
+Under `--json`, stdout holds the document and nothing else. The startup
+banner is suppressed, as `--quiet` and `--cron` suppress it, and the
+progress narration a command would otherwise print — such as the stale
+local records `prune` reconciles away — is suppressed too, so it cannot
+land ahead of the document. Every `--json` command therefore pipes on
+its own, with no additional flag: `vaultik snapshot list --json | jq .`
+and `vaultik prune --json | jq .` both work as written.
 
 ### environment variables
 

TODO.md

@@ -25,6 +25,62 @@ release" is exactly the contradiction
 
 # Completed Steps
 
+- 2026-08-09: Finished the `--json` stdout contract and gave `make build`
+  a rule ([issue #108](https://git.eeqj.de/sneak/vaultik/issues/108),
+  [issue #110](https://git.eeqj.de/sneak/vaultik/issues/110)). Two
+  unrelated defects of the same shape — a command reporting something it
+  did not do — landed together because both are small.
+
+  `CleanupLocalSnapshots` wrote three prose lines to stdout with no
+  `--json` awareness, covering every branch of the function, so no input
+  avoided them and `vaultik prune --json | jq` failed even after
+  [issue #106](https://git.eeqj.de/sneak/vaultik/issues/106) removed the
+  banner. `-q` never helped either: `printlnStdout` and `stdoutf` write
+  straight to `Vaultik.Stdout` and never consult `Vaultik.UI`, which is
+  what `SetQuiet` affects. The issue offered three fixes and asked for a
+  decision. Taken: thread `*PruneOptions` into the function and gate each
+  write on `!opts.JSON`, matching `PruneBlobs` (its sibling phase, which
+  already takes the same struct), `RemoveSnapshot` and `remote info`, so
+  the package has one pattern rather than two. Rejected: moving the lines
+  to `log.Info`, because the logger's default level is `slog.LevelWarn`,
+  so that would not relocate them to stderr — it would delete them from a
+  plain `vaultik prune`, and the removal of rows from the local index is
+  not something to narrate only under `--verbose`. Also rejected: putting
+  the stale-record count into `PruneBlobsResult`, whose every field is
+  blob-scoped and which is produced by the later phase; a prune document
+  covering both phases is a reasonable thing to want, but it is a schema
+  design question and not a stream-hygiene fix. The narration is
+  duplicated as `log.Info` records, which `PruneBlobs` already does
+  alongside its own prints, so the events survive on stderr for anyone
+  running `--verbose`.
+
+  `make build` printed "Nothing to be done for 'build'" and exited 0
+  without producing a binary: `build` was listed in `.PHONY` with no
+  `build:` rule anywhere, and declaring a name phony is exactly what
+  converts make's "No rule to make target" error into a silent success.
+  Fixed with `build: vaultik`, keeping `vaultik:` as the file rule. The
+  audit the issue asked for covers all 19 `.PHONY` names; `build` was the
+  only one without a rule, and `vaultik` is correctly absent from
+  `.PHONY`, being a real file target.
+
+  Tests, each verified to fail with the fix reverted rather than assumed
+  to: `CleanupLocalSnapshots` leaves stdout untouched under `--json` in
+  all three branches (stale records, none, empty index) and still emits
+  every line without it, so the guard cannot be satisfied by deleting the
+  output; `prune --json` run end to end through `Entry`, cobra and fx
+  over the process's real stdout descriptor against a `file://` store,
+  asserting exactly one JSON document, in both the stale and non-stale
+  branches; and a parse of the `Makefile` asserting every `.PHONY` name
+  has a rule and that `build` reaches the rule that produces the binary,
+  which keeps the audit true for names added later. That last one is a
+  parse rather than an invocation of `make`, since `make test` is what
+  runs it and shelling back into `make build` would nest a build inside
+  the test run. The property a parse cannot establish — that the recipe
+  still fails when the build fails — was verified by hand against a
+  deliberately broken tree: `make build` exits 2 and produces nothing.
+  `cmd/vaultik` gains its first test file, so `make test` now reports 16
+  packages `ok` where it reported 15.
+
 - 2026-08-09: Stopped the startup banner from contaminating `--json`
   documents ([issue #106](https://git.eeqj.de/sneak/vaultik/issues/106)).
   `Entry` writes the banner to stdout before cobra parses anything, and

cmd/vaultik/makefile_test.go

@@ -0,0 +1,169 @@
+package main_test
+
+import (
+	"os"
+	"path/filepath"
+	"regexp"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// This file guards the Makefile that builds this program, which is why
+// it lives beside it rather than in a package of its own.
+//
+// Issue #110: `build` was listed in .PHONY with no `build:` rule
+// anywhere in the file. That combination is silently successful — make
+// considers a phony target with no prerequisites and no recipe already
+// satisfied, so `rm -f vaultik && make build` printed "Nothing to be
+// done for 'build'" and exited 0 with no binary produced. Declaring the
+// name phony is precisely what converts the "No rule to make target"
+// error into a green.
+//
+// The guard is a parse of the Makefile rather than an invocation of
+// make. `make test` is what runs these tests, so shelling back into
+// `make build` here would nest a build inside the test run and drop a
+// binary into the tree as a side effect of testing. The one property a
+// parse cannot establish — that the recipe still fails when the build
+// fails — is not testable from inside the build either; it is verified
+// by hand against a deliberately broken tree.
+
+// phonyDirective introduces the list of phony target names.
+const phonyDirective = ".PHONY:"
+
+// ruleLine matches a rule's target list: a target starts in column
+// zero, so recipe lines (tab-indented) and the continuation lines of a
+// variable assignment (space-indented) are excluded by construction.
+//
+// The trailing (?:[^=]|$) rejects `:=` assignments such as
+// `VERSION := $(shell script/version)`, which are not rules. Directives
+// and function calls (`.PHONY:`, `ifeq`, `$(error ...)`) do not match
+// because a target here must begin with a letter, digit or underscore.
+var ruleLine = regexp.MustCompile(`^([A-Za-z0-9_][A-Za-z0-9_./ -]*):(?:[^=]|$)`)
+
+// TestPhonyTargetsAllHaveRules fails on any name in .PHONY that has no
+// rule in the Makefile. Such a name is not a build target at all: it is
+// a command that reports success without doing anything, which is worse
+// than one that does not exist, because a caller checking the exit code
+// cannot tell the difference.
+func TestPhonyTargetsAllHaveRules(t *testing.T) {
+	t.Parallel()
+
+	makefile := readMakefile(t)
+
+	phony := phonyTargets(makefile)
+	require.NotEmpty(t, phony, "no .PHONY names found; the parser is broken")
+
+	rules := declaredRules(makefile)
+
+	// Sanity check on the rule parser before trusting its verdict: a
+	// parser that found nothing would pass this test by accident.
+	require.Contains(t, rules, "vaultik",
+		"the file rule that builds the binary must be recognized")
+
+	for _, target := range phony {
+		assert.Contains(t, rules, target,
+			"`.PHONY` lists %q but the Makefile declares no %q rule, so "+
+				"`make %s` exits 0 without doing anything", target, target, target)
+	}
+}
+
+// TestBuildTargetBuildsTheBinary pins the specific shape of issue #110:
+// `make build` has to reach the rule that produces the binary. The test
+// above would also pass if `build:` were given an empty recipe of its
+// own, which would be the same silent success under a different
+// spelling.
+func TestBuildTargetBuildsTheBinary(t *testing.T) {
+	t.Parallel()
+
+	prerequisites := rulePrerequisites(readMakefile(t), "build")
+	require.NotNil(t, prerequisites, "the Makefile declares no `build` rule")
+
+	assert.Contains(t, prerequisites, "vaultik",
+		"`make build` must depend on the rule that builds the binary")
+}
+
+// readMakefile returns the contents of the repository's Makefile. The
+// test binary runs with its package directory as the working directory,
+// so the root is found by walking up until the Makefile appears.
+func readMakefile(t *testing.T) string {
+	t.Helper()
+
+	dir, err := os.Getwd()
+	require.NoError(t, err)
+
+	for {
+		//nolint:gosec // G304: the path is this test's own directory walk
+		contents, err := os.ReadFile(filepath.Join(dir, "Makefile"))
+		if err == nil {
+			return string(contents)
+		}
+
+		parent := filepath.Dir(dir)
+		require.NotEqual(t, dir, parent,
+			"walked to the filesystem root without finding a Makefile")
+
+		dir = parent
+	}
+}
+
+// phonyTargets returns every name declared phony, across all .PHONY
+// lines.
+func phonyTargets(makefile string) []string {
+	var targets []string
+
+	for line := range strings.SplitSeq(makefile, "\n") {
+		if !strings.HasPrefix(line, phonyDirective) {
+			continue
+		}
+
+		targets = append(targets,
+			strings.Fields(strings.TrimPrefix(line, phonyDirective))...)
+	}
+
+	return targets
+}
+
+// declaredRules returns the set of target names that have a rule.
+func declaredRules(makefile string) map[string]bool {
+	rules := make(map[string]bool)
+
+	for line := range strings.SplitSeq(makefile, "\n") {
+		match := ruleLine.FindStringSubmatch(line)
+		if match == nil {
+			continue
+		}
+
+		// One rule may name several targets: `a b: prereq`.
+		for target := range strings.FieldsSeq(match[1]) {
+			rules[target] = true
+		}
+	}
+
+	return rules
+}
+
+// rulePrerequisites returns the prerequisites of the named rule, or nil
+// if no such rule exists. A rule with none returns an empty slice, so
+// "declared with nothing to do" is distinguishable from "not declared".
+func rulePrerequisites(makefile, target string) []string {
+	for line := range strings.SplitSeq(makefile, "\n") {
+		match := ruleLine.FindStringSubmatch(line)
+		if match == nil {
+			continue
+		}
+
+		if !slices.Contains(strings.Fields(match[1]), target) {
+			continue
+		}
+
+		_, after, _ := strings.Cut(line, ":")
+
+		return append([]string{}, strings.Fields(after)...)
+	}
+
+	return nil
+}

internal/cli/entry_banner_test.go

@@ -30,6 +30,11 @@ const (
 
 	flagJSON   = "--json"
 	flagQuiet  = "--quiet"
+	flagConfig = "--config"
+
+	// programName is argv[0] as the real process receives it. Entry
+	// strips it before scanning, so it has to be present.
+	programName = "vaultik"
 
 	// someSnapshotID is any snapshot identifier: these tests never run
 	// the command, so it only has to occupy the positional argument.
@@ -65,7 +70,7 @@ var jsonArgumentVectors = map[string][]string{
 	// A --json invocation that also carries a flag with a value, so the
 	// scan cannot be fooled by an argument that consumes the next one.
 	"json with config": {
-		"--config", "/nonexistent/vaultik.yml", cmdSnapshot, cmdList, flagJSON,
+		flagConfig, "/nonexistent/vaultik.yml", cmdSnapshot, cmdList, flagJSON,
 	},
 }
 
@@ -222,7 +227,7 @@ func TestEntryJSONStdoutIsExactlyOneDocument(t *testing.T) {
 	})
 
 	os.Args = []string{
-		"vaultik", "--config", configPath, cmdSnapshot, cmdList, flagJSON,
+		programName, flagConfig, configPath, cmdSnapshot, cmdList, flagJSON,
 	}
 
 	stdout := captureProcessStdout(t, Entry)

internal/cli/entry_prune_json_test.go

@@ -0,0 +1,165 @@
+package cli //nolint:testpackage // shares hermeticConfig and the capture helpers
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/adrg/xdg"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/types"
+)
+
+// pruneJSONDocument is the shape `prune --json` writes: the
+// PruneBlobsResult document, and nothing else.
+//
+//nolint:tagliatelle // snake_case is the established JSON output format
+type pruneJSONDocument struct {
+	BlobsFound   int   `json:"blobs_found"`
+	BlobsDeleted int   `json:"blobs_deleted"`
+	BytesFreed   int64 `json:"bytes_freed"`
+}
+
+// stalePruneSnapshotID is seeded into the local index with no manifest
+// on the destination store, which is exactly what makes it stale.
+const stalePruneSnapshotID = "test-host_test_2026-04-01T09:00:00Z"
+
+// TestEntryPruneJSONStdoutIsExactlyOneDocument is the end-to-end
+// regression guard for issue #108: `vaultik prune --json | jq .` must
+// work with no other flags.
+//
+// It runs Entry over the process's real stdout descriptor, through
+// cobra and the fx graph, against a hermetic file:// destination store
+// — the same construction TestEntryJSONStdoutIsExactlyOneDocument uses
+// for `snapshot list`, with the pipe to jq replaced by a decoder.
+//
+// Both branches of the local-snapshot reconciliation are exercised
+// because the three stdout writes that broke this covered all of them:
+// one line per stale record and a summary when there were any, and a
+// "No stale local snapshots found." line when there were none. No input
+// avoided the contamination, so no single branch demonstrates the fix.
+//
+// Not parallel: it replaces os.Args, os.Stdout and the xdg globals.
+//
+//nolint:paralleltest // replaces os.Args, os.Stdout and the xdg globals
+func TestEntryPruneJSONStdoutIsExactlyOneDocument(t *testing.T) {
+	for _, testCase := range []struct {
+		name        string
+		seedStale   bool
+		description string
+	}{
+		{
+			name:        "no stale local records",
+			seedStale:   false,
+			description: "the empty-index branch used to print a 'No stale' line",
+		},
+		{
+			name:      "stale local records present",
+			seedStale: true,
+			description: "the removal branch used to print a line per record " +
+				"plus a summary",
+		},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			configPath := writeHermeticPruneConfig(t, testCase.seedStale)
+
+			previousArgs := os.Args
+
+			t.Cleanup(func() {
+				os.Args = previousArgs
+				rootFlags = RootFlags{}
+			})
+
+			os.Args = []string{
+				programName, flagConfig, configPath, cmdPrune, flagJSON,
+			}
+
+			stdout := captureProcessStdout(t, Entry)
+
+			requireExactlyOneJSONDocument(t, stdout)
+
+			var document pruneJSONDocument
+
+			require.NoError(t, json.Unmarshal([]byte(stdout), &document),
+				testCase.description)
+
+			// A destination store with no blobs has none to prune. The
+			// assertion that matters is the one above; this one keeps the
+			// test honest about which document it decoded.
+			assert.Equal(t, 0, document.BlobsFound)
+		})
+	}
+}
+
+// writeHermeticPruneConfig builds a config over a temp directory and, if
+// seedStale is set, creates the index database up front with one
+// snapshot record that has no counterpart on the destination store.
+// Returns the config path.
+func writeHermeticPruneConfig(t *testing.T, seedStale bool) string {
+	t.Helper()
+
+	dir := t.TempDir()
+	configPath := filepath.Join(dir, "config.yml")
+	indexPath := filepath.Join(dir, "index.sqlite")
+
+	contents := fmt.Sprintf(hermeticConfig,
+		filepath.Join(dir, "source"),
+		filepath.Join(dir, "store"),
+		indexPath)
+
+	require.NoError(t,
+		os.WriteFile(configPath, []byte(contents), configFileMode))
+
+	// The PID lock lives under xdg.DataHome, which xdg resolves at
+	// package init; point it at the temp dir so the test neither
+	// touches nor collides with the real one.
+	t.Setenv("XDG_DATA_HOME", filepath.Join(dir, "data"))
+	xdg.Reload()
+	t.Cleanup(xdg.Reload)
+
+	if seedStale {
+		seedStaleSnapshotRecord(t, indexPath)
+	}
+
+	return configPath
+}
+
+// seedStaleSnapshotRecord creates the index database at path and
+// inserts one completed snapshot into it. Nothing is written to the
+// destination store, so `prune` finds the record stale and removes it —
+// the branch that printed a line per record.
+func seedStaleSnapshotRecord(t *testing.T, path string) {
+	t.Helper()
+
+	ctx := context.Background()
+
+	db, err := database.New(ctx, path)
+	require.NoError(t, err)
+
+	defer func() { require.NoError(t, db.Close()) }()
+
+	startedAt := time.Date(2026, 4, 1, 9, 0, 0, 0, time.UTC)
+	completedAt := startedAt.Add(time.Minute)
+
+	snap := &database.Snapshot{
+		ID:             types.SnapshotID(stalePruneSnapshotID),
+		Hostname:       "test-host",
+		VaultikVersion: "test",
+		StartedAt:      startedAt,
+		CompletedAt:    &completedAt,
+	}
+
+	repos := database.NewRepositories(db)
+
+	err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+		return repos.Snapshots.Create(ctx, tx, snap)
+	})
+	require.NoError(t, err)
+}

internal/vaultik/prune.go

@@ -79,7 +79,7 @@ func (v *Vaultik) Prune(opts *PruneOptions) error {
 	// store is treated as gone. This used to be the separate 'snapshot
 	// cleanup' command and is now folded in so a single 'vaultik prune'
 	// gets the local index fully back in sync with the destination.
-	err = v.CleanupLocalSnapshots()
+	err = v.CleanupLocalSnapshots(opts)
 	if err != nil {
 		return fmt.Errorf("reconciling local snapshots with remote: %w", err)
 	}

internal/vaultik/prune_cleanup_test.go

@@ -0,0 +1,134 @@
+package vaultik_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// cleanupStaleID is a local snapshot record with no remote manifest —
+// the record CleanupLocalSnapshots exists to remove.
+const cleanupStaleID = "testhost_home_2026-04-01T09:00:00Z"
+
+// remainingSnapshotLimit bounds the post-cleanup listing. ListRecent
+// takes a SQL LIMIT, so it must be positive; the fixtures never exceed
+// a handful of rows.
+const remainingSnapshotLimit = 100
+
+// cleanupStart is the fixture snapshot's start time. Its exact value is
+// irrelevant; only presence in the index matters here.
+//
+//nolint:gochecknoglobals // read-only fixture shared by the tests below
+var cleanupStart = time.Date(2026, 4, 1, 9, 0, 0, 0, time.UTC)
+
+// TestCleanupLocalSnapshots_JSONWritesNothingToStdout is the regression
+// guard for issue #108: `vaultik prune --json | jq` failed because this
+// function wrote prose to stdout on every branch, ahead of the
+// PruneBlobsResult document, with no --json awareness at all.
+//
+// Both branches are covered because the three writes between them left
+// no input that avoided the contamination: with stale records there was
+// a line per record plus a summary, and with none there was still the
+// "No stale local snapshots found." line.
+func TestCleanupLocalSnapshots_JSONWritesNothingToStdout(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	for name, seed := range map[string]func(*listEnv){
+		"no stale records": func(env *listEnv) {
+			// A snapshot present both locally and remotely: nothing to
+			// remove, which used to print the "No stale" line.
+			env.addLocal(t, listLocalID, cleanupStart)
+			env.addRemote(t, listLocalID, cleanupStart)
+		},
+		"stale records present": func(env *listEnv) {
+			env.addLocal(t, cleanupStaleID, cleanupStart)
+		},
+		"nothing at all": func(_ *listEnv) {},
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			env := newListEnv(t)
+			seed(env)
+
+			err := env.v.CleanupLocalSnapshots(&vaultik.PruneOptions{JSON: true})
+			require.NoError(t, err)
+
+			assert.Empty(t, env.stdout.String(),
+				"stdout carries the --json document and nothing else")
+		})
+	}
+}
+
+// TestCleanupLocalSnapshots_HumanOutputRetained pins the other half of
+// the contract. Without it the test above would be satisfied by
+// deleting the three lines outright, and a `vaultik prune` with no
+// flags must still say that it removed records from the local index —
+// that is the deletion of local state, not decoration.
+func TestCleanupLocalSnapshots_HumanOutputRetained(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	t.Run("stale records present", func(t *testing.T) {
+		t.Parallel()
+
+		env := newListEnv(t)
+		env.addLocal(t, cleanupStaleID, cleanupStart)
+
+		err := env.v.CleanupLocalSnapshots(&vaultik.PruneOptions{})
+		require.NoError(t, err)
+
+		out := env.stdout.String()
+
+		assert.Contains(t, out, "Removing stale local record: "+cleanupStaleID)
+		assert.Contains(t, out, "Removed 1 stale local snapshot record(s).")
+	})
+
+	t.Run("no stale records", func(t *testing.T) {
+		t.Parallel()
+
+		env := newListEnv(t)
+		env.addLocal(t, listLocalID, cleanupStart)
+		env.addRemote(t, listLocalID, cleanupStart)
+
+		err := env.v.CleanupLocalSnapshots(&vaultik.PruneOptions{})
+		require.NoError(t, err)
+
+		assert.Contains(t, env.stdout.String(),
+			"No stale local snapshots found.")
+	})
+}
+
+// TestCleanupLocalSnapshots_RemovesOnlyStaleRecords checks that the
+// --json gate did not change what the function does, only what it
+// says: the stale record is gone from the index and the one with a
+// remote manifest is untouched.
+func TestCleanupLocalSnapshots_RemovesOnlyStaleRecords(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newListEnv(t)
+	env.addLocal(t, listLocalID, cleanupStart)
+	env.addRemote(t, listLocalID, cleanupStart)
+	env.addLocal(t, cleanupStaleID, cleanupStart)
+
+	err := env.v.CleanupLocalSnapshots(&vaultik.PruneOptions{JSON: true})
+	require.NoError(t, err)
+
+	remaining, err := env.v.Repositories.Snapshots.ListRecent(
+		env.v.Context(), remainingSnapshotLimit)
+	require.NoError(t, err)
+
+	ids := make([]string, 0, len(remaining))
+	for _, snap := range remaining {
+		ids = append(ids, snap.ID.String())
+	}
+
+	assert.Equal(t, []string{listLocalID}, ids,
+		"only the record with no remote manifest may be removed")
+}

internal/vaultik/snapshot.go

@@ -829,7 +829,15 @@ func (v *Vaultik) outputVerifyJSON(result *VerifyResult) error {
 // behind by incomplete or interrupted backups. Each local snapshot's
 // human ID is hashed via RemoteSnapshotKey and compared against the
 // remote listing.
-func (v *Vaultik) CleanupLocalSnapshots() error {
+//
+// It takes the whole *PruneOptions, symmetric with PruneBlobs, because
+// it is the other half of one command: Prune runs this phase and then
+// that one. Only JSON is read here. Under --json every write below is
+// suppressed, because stdout carries the PruneBlobsResult document and
+// nothing else — prose ahead of it is what made `vaultik prune --json |
+// jq` fail (issue #108). The narration is duplicated as log records,
+// which go to stderr and so cannot corrupt the document.
+func (v *Vaultik) CleanupLocalSnapshots(opts *PruneOptions) error {
 	err := v.EnsureStorageBinding()
 	if err != nil {
 		return err
@@ -855,7 +863,11 @@ func (v *Vaultik) CleanupLocalSnapshots() error {
 	for _, snap := range localSnapshots {
 		id := snap.ID.String()
 		if !remoteSet[snapshot.RemoteSnapshotKey(id)] {
+			log.Info("Removing stale local snapshot record", "snapshot_id", id)
+
+			if !opts.JSON {
 				v.stdoutf("Removing stale local record: %s\n", id)
+			}
 
 			err = v.deleteSnapshotFromLocalDB(id)
 			if err != nil {
@@ -869,6 +881,13 @@ func (v *Vaultik) CleanupLocalSnapshots() error {
 		}
 	}
 
+	log.Info("Reconciled local snapshot records against remote metadata",
+		"removed", removed, "examined", len(localSnapshots))
+
+	if opts.JSON {
+		return nil
+	}
+
 	if removed == 0 {
 		v.printlnStdout("No stale local snapshots found.")
 	} else {