fix(composer): stop NBSP idle rows from blocking empty verdicts

.agents/skills/afk/SKILL.md

@@ -192,7 +192,7 @@ the operational prefix lets firstmate distinguish it from a real captain message
 - The active backend passes its capture plus declarative styled, cursor, identity, and row capabilities to the shared screen classifier; all structural recognition and verdict logic remains in `bin/fm-composer-lib.sh`.
   Styled captures let that owner remove dim/faint and dark-TRUECOLOR ghost or placeholder text while shape detection uses the ANSI-stripped screen, so a dark border is not lost with ghost content.
   A ghost-only or idle bordered composer such as claude's `│ > ... │` therefore reads empty without allowing an unbordered shell prompt to do the same.
-  `FM_COMPOSER_IDLE_RE` overrides the shared idle-placeholder regex, but a match alone never bypasses the classifier's shape-specific position and ANSI de-emphasis safety gates.
+  `FM_COMPOSER_IDLE_RE` overrides the shared idle-placeholder regex; see `docs/configuration.md`'s `FM_COMPOSER_IDLE_RE` entry for exactly which rows a match can and cannot bypass gates for.
   `FM_BUSY_REGEX` overrides the rendered delivery guards plus Grok's isolated task-state fallback.
   A blank or otherwise unidentified input row carries no positive container proof and defers injection, so a modal dialog or a mid-redraw pane is never an injection target.
 - **Max-defer escape** - the daemon must never silently wedge. If anything stays

bin/fm-composer-lib.sh

@@ -965,26 +965,41 @@ _fm_composer_row_content() {  # <raw-row> <styled> -> content on stdout
 # _fm_composer_classify_rows: shared multi-row container verdict for the box
 # and separated shapes: pending beats empty, an unreadable row is unknown, and
 # geometry ambiguity turns pending into pending-unproven and empty into
-# unknown (an ambiguous container is not positive proof).
+# unknown (an ambiguous container is not positive proof). A row that is
+# nothing but a known idle placeholder is furniture, not a vote for pending,
+# regardless of whether ghost stripping could prove it dim - but furniture
+# rows are only ever excused, never themselves the proof: skipping every row
+# in the box leaves no positive evidence of emptiness (indistinguishable from
+# real typed text that happens to match the placeholder pattern, e.g. a
+# caller-supplied FM_COMPOSER_IDLE_RE override), so at least one row must
+# still resolve to empty on its own merits before the box reads empty.
 _fm_composer_classify_rows() {  # <screen> <styled> <ambiguous> <first-row> <last-row>
   local screen=$1 styled=$2 ambiguous=$3 first=$4 last=$5
-  local row raw content plain state unknown_seen=0
+  local row raw content plain state unknown_seen=0 empty_seen=0
+  local idle_re=${FM_COMPOSER_IDLE_RE:-$FM_COMPOSER_IDLE_RE_DEFAULT}
+  local furniture_re="^(${idle_re})$"
   row=$first
   while [ "$row" -le "$last" ]; do
     raw=$(_fm_composer_screen_row "$row" "$screen")
     content=$(_fm_composer_row_content "$raw" "$styled")
     plain=$(_fm_composer_row_content "$raw" 0)
+    if [ -n "$content" ] && fm_composer_idle_matches "$content" "$furniture_re" insensitive; then
+      row=$((row + 1))
+      continue
+    fi
     state=$(fm_composer_classify_content 1 "$content" \
-      "${FM_COMPOSER_IDLE_RE:-$FM_COMPOSER_IDLE_RE_DEFAULT}" insensitive "$plain" 1 "$styled")
+      "$idle_re" insensitive "$plain" 1 "$styled")
     case "$state" in
       pending)
         if [ "$ambiguous" = 1 ]; then printf 'pending-unproven'; else printf 'pending'; fi
         return 0
         ;;
       unknown) unknown_seen=1 ;;
+      empty) empty_seen=1 ;;
     esac
     row=$((row + 1))
   done
+  if [ "$empty_seen" != 1 ]; then unknown_seen=1; fi
   if [ "$unknown_seen" = 1 ] || [ "$ambiguous" = 1 ]; then
     printf 'unknown'
   else

docs/configuration.md

@@ -1080,7 +1080,7 @@ FM_FLEET_SYNC_PACKED_REFS_LOCK_RETRIES=3        # fetch retries after fm-fleet-s
 FM_FLEET_SYNC_PACKED_REFS_LOCK_RETRY_WAIT_SECS=1 # seconds fm-fleet-sync.sh waits before each of those retries
 FM_FLEET_SYNC_PACKED_REFS_LOCK_AGE_SECS=30       # min mtime age before fm-fleet-sync.sh treats a leftover packed-refs.lock as provably stale
 FM_BUSY_REGEX=          # optional override for rendered delivery guards and Grok's isolated task-state fallback; converted worker state ignores it
-FM_COMPOSER_IDLE_RE=    # optional fleet-wide idle-placeholder regex override (bin/fm-composer-lib.sh); a match alone does not prove emptiness because shape-specific position and ANSI de-emphasis safety gates still apply
+FM_COMPOSER_IDLE_RE=    # optional fleet-wide idle-placeholder regex override (bin/fm-composer-lib.sh); inside a bordered box or separated composer, only an exact full-row match is excluded from the pending vote regardless of styling, and a box whose only content matches still reads unknown rather than empty; these guards cover exact matching rows and furniture-only boxes, so operators remain responsible for ensuring an override does not exactly match real input
 FM_COMPOSER_CAPTURE_LINES=20   # fleet-wide bound for tail-capture composer reads; tmux instead supplies its bounded visible pane, while the other adapters use this small window so stale scrollback banners stay out of the candidate set
 FM_COMPOSER_PI_MAX_LINES=8     # fleet-wide: maximum rows admitted between Pi's identity-corroborated separator pair; taller or ambiguous candidates stay unknown
 FM_COMPOSER_GHOST_LUMA_MAX=128   # fleet-wide: max perceived luminance (0.299R+0.587G+0.114B, 0-255) for a TRUECOLOR foreground to count as de-emphasised ghost/placeholder text and be stripped; dim/faint (SGR 2) is stripped regardless. Assumes a dark terminal theme (bin/fm-composer-lib.sh's fm_composer_strip_ghost, used by styled tmux, herdr, and Zellij reads)

tests/fm-composer-ghost.test.sh

@@ -479,7 +479,13 @@ test_unproved_empty_geometry_fails_closed() {
           fm_tmux_composer_state "fakepane")
         ;;
       idle)
-        expected=pending-unproven
+        # A row matching the idle-placeholder regex is excused as furniture
+        # regardless of styling (issue #2483's hint-row-poisoning case), so
+        # this row casts no pending vote; furniture alone is never positive
+        # proof of emptiness though, and no other row in this single-row box
+        # reads empty on its own merits, so the box falls to unknown, same as
+        # the ghost case above.
+        expected=unknown
         printf '╭────────────╮\n│ idle hint │\n╰────────────╯\n' > "$capture"
         out=$(PATH="$fb:$PATH" FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
           FM_COMPOSER_IDLE_RE='^idle hint$' fm_tmux_composer_state "fakepane")
@@ -494,7 +500,7 @@ test_unproved_empty_geometry_fails_closed() {
     [ "$out" = "$expected" ] \
       || fail "unproved geometry '$fixture' should be $expected, got '$out'"
   done
-  pass "fm_tmux_composer_state: unproved ghost and malformed geometry stay unknown while styled placeholder-like text stays pending-unproven"
+  pass "fm_tmux_composer_state: unproved ghost, idle-placeholder, and malformed geometry all fail closed to unknown"
 }
 
 test_differing_widths_use_asymmetric_verdicts() {
@@ -530,6 +536,71 @@ test_wide_composer_text_is_pending() {
   pass "fm_tmux_composer_state: emoji and CJK text remain pending under the C locale"
 }
 
+test_claude_nbsp_idle_row_is_empty() {
+  local dir fb capture out nbsp
+  dir="$TMP_ROOT/claude-nbsp"; mkdir -p "$dir"
+  fb=$(make_fake_tmux "$dir")
+  capture="$dir/styled.txt"
+  nbsp=$(printf '\302\240')
+
+  # Claude's idle bordered composer uses U+276F followed by U+00A0. The tmux
+  # daemon runs under LC_ALL=C, where POSIX whitespace matching alone does not
+  # trim that separator (issue #2483).
+  printf '╭────────────╮\n│ ❯%s         │\n╰────────────╯\n' "$nbsp" > "$capture"
+  out=$(PATH="$fb:$PATH" LC_ALL=C FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
+    fm_tmux_composer_state "fakepane")
+  [ "$out" = empty ] \
+    || fail "Claude's bordered U+276F+NBSP idle row should be empty, got '$out'"
+
+  printf '╭────────────╮\n│ ❯ fix      │\n╰────────────╯\n' > "$capture"
+  out=$(PATH="$fb:$PATH" LC_ALL=C FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
+    fm_tmux_composer_state "fakepane")
+  [ "$out" = pending ] \
+    || fail "Claude's bordered composer with typed text should be pending, got '$out'"
+  pass "fm_tmux_composer_state: Claude's bordered U+276F+NBSP idle row is empty while typed text stays pending"
+}
+
+test_bright_furniture_row_does_not_poison_idle_verdict() {
+  local dir fb capture out nbsp
+  dir="$TMP_ROOT/furniture-row"; mkdir -p "$dir"
+  fb=$(make_fake_tmux "$dir")
+  capture="$dir/styled.txt"
+  nbsp=$(printf '\302\240')
+
+  # A bright (non-dim, non-truecolor-ghosted) suggestion row below the idle
+  # glyph row - issue #2483's "hint-row poisoning": _fm_composer_classify_rows
+  # applies pending-beats-empty across every row in the box, so a furniture
+  # row that ghost-stripping cannot remove used to win over the otherwise-
+  # empty glyph row. A row matching the shared idle-placeholder regex is
+  # recognized furniture regardless of styling, so the box stays empty.
+  printf '╭────────────────────╮\n│ ❯%s                 │\n│ Ask anything...    │\n╰────────────────────╯\n' \
+    "$nbsp" > "$capture"
+  out=$(PATH="$fb:$PATH" LC_ALL=C FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
+    fm_tmux_composer_state "fakepane")
+  [ "$out" = empty ] \
+    || fail "a bright idle-placeholder furniture row should not poison an empty composer, got '$out'"
+
+  # Real typed text on that same second row must still read pending - the
+  # furniture exception is a regex match on known placeholder text, not a
+  # blanket pass for every non-glyph row.
+  printf '╭────────────────────╮\n│ ❯%s                 │\n│ fix the login bug  │\n╰────────────────────╯\n' \
+    "$nbsp" > "$capture"
+  out=$(PATH="$fb:$PATH" LC_ALL=C FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
+    fm_tmux_composer_state "fakepane")
+  [ "$out" = pending ] \
+    || fail "real typed text on a second composer row should stay pending, got '$out'"
+
+  # A draft that merely starts with a known placeholder must not be swallowed
+  # as furniture when another row independently proves the box empty.
+  printf '╭────────────────────╮\n│ ❯%s                 │\n│ Ask anything... x  │\n╰────────────────────╯\n' \
+    "$nbsp" > "$capture"
+  out=$(PATH="$fb:$PATH" LC_ALL=C FM_FAKE_STYLED="$capture" FM_FAKE_CY=1 \
+    fm_tmux_composer_state "fakepane")
+  [ "$out" = pending ] \
+    || fail "a draft extending an idle-placeholder prefix should stay pending, got '$out'"
+  pass "fm_tmux_composer_state: a bright idle-placeholder furniture row does not poison an empty composer, real text still pending"
+}
+
 test_all_tmux_harness_composers_share_classification() {
   local dir fb capture out harness
   dir="$TMP_ROOT/all-harness-composers"; mkdir -p "$dir"
@@ -706,6 +777,8 @@ test_misaligned_box_is_unknown
 test_unproved_empty_geometry_fails_closed
 test_differing_widths_use_asymmetric_verdicts
 test_wide_composer_text_is_pending
+test_claude_nbsp_idle_row_is_empty
+test_bright_furniture_row_does_not_poison_idle_verdict
 test_all_tmux_harness_composers_share_classification
 test_unrecognized_state_defers_input_guard
 test_single_capture_leaves_no_fallback_race