fleetd #635 follow-up: redact() masks block-scalar continuations + passphrase; --set failures stop echoing the value (defects 7 and 8, criteria 15a/15b/16)

Defect 7 (comment 17670): redact() only masked a line that itself started with a
secret-looking key, so a YAML block scalar's value leaked on the lines that
followed the key while the key line right above it printed a reassuring
"<redacted>". Fixed by tracking the masked key's own indentation and masking
every following line indented deeper than it, stopping once indentation returns
to the key's level or shallower; the diff's leading +/-/space marker is stripped
before indentation is measured, per the comment's own pitfall. "passphrase" is
now also in the key-name backstop.

Defect 8 (comment 17673): apply_set_pairs echoed the operator's full
"path=value" input, unredacted, in both of its yq-failure die messages — a
failing --set with a secret-looking value printed that value right back. Fixed
to print only the path; deliberately not routed through redact, which would
pass a non-"key: value"-shaped string straight through.

Adds acceptance criteria 15a (block-scalar continuation), 15b (passphrase key),
and 16 (failing --set never echoes its value) to scripts/test-config-edit.sh,
each with a positive control proving the relevant line really was in the
printed output before asserting the secret is absent. All three confirmed RED
against the pre-fix code and GREEN after, in isolation, before being folded
into the full suite (16 criteria + 3 extras, exit 0).

Also updates PR #636's description per comment 17671: the redact() sentence now
names the continuation-masking rule and says plainly that the key-name list is
a backstop, never a complete list.

scripts/test-config-edit.sh

@@ -382,6 +382,124 @@ test_restore_message_names_the_searched_directory() {
     || fail "--restore with a real backup present must put the file back byte for byte"
 }
 
+# ------------------------- acceptance criterion 15a: block-scalar continuation lines are redacted
+# fleetd #635 follow-up (ticket comment 17670, defect 7) — redact() used to look only AT the key
+# line. A YAML block scalar (`|`) puts its value on the lines that FOLLOW the key, each indented
+# deeper than it, so the real secret flowed through untouched while the key line right above it
+# printed a reassuring "<redacted>" — worse than no redaction, because the marker stops a reader
+# from looking further. The edited key here ("retries") sits directly next to the block scalar,
+# well inside diff -u's default 3-line context window, so the printed hunk is GUARANTEED to
+# include the secret's lines — placing the edit further away would let this pass today even
+# without the fix, proving nothing (the ticket comment's own warning, from the lead's first
+# reproduction attempt). The positive control runs FIRST: without it, "the secret never entered
+# the diff at all" would pass identically to "it entered and was correctly redacted".
+new_fixture_block_scalar() {
+  local dir
+  dir="$(mktemp -d "$TMP/fixture.XXXXXX")"
+  cat > "$dir/fleetd.yaml" <<'YAML'
+bind:
+  host: 127.0.0.1
+  port: 19999
+broker:
+  uri: amqp://user:hunter2@host/vhost
+auth:
+  token: |
+    FAKELEAK-BLOCK-SCALAR
+  retries: 1
+profiles:
+  sonnet:
+    weight: 3
+    maxLoad: 5
+YAML
+  : > "$dir/fleetd.out"
+  printf '%s' "$dir"
+}
+
+test_block_scalar_continuation_is_redacted() {
+  local dir
+  dir="$(new_fixture_block_scalar)"
+
+  start_run "$dir" 5 --set '.auth.retries=2'
+  sleep 1
+  printf 'config reloaded\n' >> "$dir/fleetd.out"
+  collect_run "$dir"
+
+  assert_equals 0 "$RUN_RC" "block-scalar case reload exit code"
+  # Positive control FIRST: the key's own (masked) line must really be in the printed diff, or the
+  # negative assertion right after proves nothing — see the comment above this test.
+  assert_contains "token:" "$RUN_OUTPUT" "block-scalar case: the key's line must be in the printed diff"
+  assert_contains "<redacted>" "$RUN_OUTPUT" "block-scalar case: redaction must be proven to have run on real content"
+  assert_not_contains "FAKELEAK-BLOCK-SCALAR" "$RUN_OUTPUT" "block-scalar case: the block scalar's VALUE must never leak"
+}
+
+# ------------------------------------- acceptance criterion 15b: "passphrase" is also recognised
+# "passphrase" was in none of TOKEN|SECRET|PASSWORD|PASSWD|CREDENTIAL|URI|_KEY (ticket comment
+# 17670). This is a plain key:value line, not a block scalar — kept in its OWN fixture and OWN
+# function, separate from criterion 15a, so that a failure in one case can never mask a failure in
+# the other (a single combined test would abort under `set -e` at its first failing assertion,
+# and the second case would then never even run).
+new_fixture_passphrase() {
+  local dir
+  dir="$(mktemp -d "$TMP/fixture.XXXXXX")"
+  cat > "$dir/fleetd.yaml" <<'YAML'
+bind:
+  host: 127.0.0.1
+  port: 19999
+broker:
+  uri: amqp://user:hunter2@host/vhost
+auth:
+  passphrase: FAKELEAK-PASSPHRASE
+  retries: 1
+profiles:
+  sonnet:
+    weight: 3
+    maxLoad: 5
+YAML
+  : > "$dir/fleetd.out"
+  printf '%s' "$dir"
+}
+
+test_passphrase_key_is_redacted() {
+  local dir
+  dir="$(new_fixture_passphrase)"
+
+  start_run "$dir" 5 --set '.auth.retries=2'
+  sleep 1
+  printf 'config reloaded\n' >> "$dir/fleetd.out"
+  collect_run "$dir"
+
+  assert_equals 0 "$RUN_RC" "passphrase case reload exit code"
+  assert_contains "passphrase:" "$RUN_OUTPUT" "passphrase case: the key's line must be in the printed diff"
+  assert_contains "<redacted>" "$RUN_OUTPUT" "passphrase case: redaction must be proven to have run on real content"
+  assert_not_contains "FAKELEAK-PASSPHRASE" "$RUN_OUTPUT" "passphrase case: the passphrase VALUE must never leak"
+}
+
+# ----------------------------------- acceptance criterion 16: a failing --set must not echo value
+# fleetd #635 follow-up (ticket comment 17673, defect 8) — apply_set_pairs used to echo the FULL
+# "$kv" (path=value, exactly as typed) in its yq-failure messages, so a broken --set with a
+# secret-looking value printed that value right back out. The path alone is what the positive
+# control proves is still there — it is what the operator needs to fix their command — and the
+# negative assertion proves the value itself never appears. Kept to exactly this one failure
+# shape (an invalid yq path/expression), matching the ticket's own reproduction.
+test_failing_set_does_not_echo_its_value() {
+  local dir rc=0
+  dir="$(new_fixture)"
+  cp "$dir/fleetd.yaml" "$dir/pre-edit.yaml"
+
+  "$EDIT" --dry-run --set '.broker.["bad=FAKELEAK-SETVALUE' \
+    --config "$dir/fleetd.yaml" --log "$dir/fleetd.out" --wait-seconds 2 \
+    > "$dir/stdout.log" 2>&1 || rc=$?
+  RUN_OUTPUT="$(cat "$dir/stdout.log")"
+
+  [ "$rc" -ne 0 ] || fail "a --set with an invalid yq expression must exit non-zero, got 0"
+  cmp -s "$dir/fleetd.yaml" "$dir/pre-edit.yaml" \
+    || fail "a failing --set must install nothing — the live fixture changed"
+  # Positive control FIRST: the path must still be in the message, or the negative assertion right
+  # after proves nothing (the message could simply have disappeared entirely).
+  assert_contains '.broker.["bad' "$RUN_OUTPUT" "the failure message must still name the PATH"
+  assert_not_contains "FAKELEAK-SETVALUE" "$RUN_OUTPUT" "the failure message must NEVER echo the VALUE"
+}
+
 # dry-run must never touch the live file and must still redact.
 test_dry_run_never_installs_and_redacts() {
   local dir before
@@ -451,6 +569,12 @@ echo "== acceptance criterion 12: the file mode survives an edit and a restore =
 test_file_mode_survives_edit_and_restore
 echo "== acceptance criterion 14: the restore message names the directory actually searched =="
 test_restore_message_names_the_searched_directory
+echo "== acceptance criterion 15a: a block scalar's continuation lines are redacted =="
+test_block_scalar_continuation_is_redacted
+echo "== acceptance criterion 15b: a passphrase key is also recognised =="
+test_passphrase_key_is_redacted
+echo "== acceptance criterion 16: a failing --set must not echo its value =="
+test_failing_set_does_not_echo_its_value
 echo "== extra: dry-run never installs, and redacts =="
 test_dry_run_never_installs_and_redacts
 echo "== extra: --check is read-only and always exits 0 =="