arcint 1.2.5 — fixes and clean-up

This is not the current release. The current one is here, with its changes in CHANGELOG.md.

A fixes and clean-up release: the 1.2.4 release review's three loop-guard
items, the round-1 follow-ups on the door's budget, and seven review leftovers
from 1.2.2/1.2.3 on the serving path. Every switch stays off by default.
With none set two things still change for clients: a streamed answer no
longer starts with the line breaks that follow the think block's closer (as
the non-streaming answer never did), and a /v1/completions prompt that ends
inside an open think block starts the turn in the block, as chat does.

• The door's budget ends every open door (ladder) — 1.2.4's ladder
  escalated only on a line at or above the threshold, so a door opened at
  detection whose share then fell below it held its masks to the token cap.
  The ladder now decides at two budget points, door_grace counted lines
  after the detection (the nudge point) and grace more (the slap point): a
  share still at or above the low mark (threshold - 0.1) nudges, then slaps,
  as before; a share below it means the model recovered, and the door lifts
  its masks (latched) instead, with no nudge or slap, so a recovered turn
  keeps its reasoning (operator, 2026-10-25). After a lift the door stays
  shut and a renewed loop follows ladder-nodoor's rule: a turn lifted at the
  nudge point is nudged at the new detection and slapped on over lines; a turn
  lifted at the slap point was already past its nudge, so the new detection
  slaps at once. The answer stays watched in a turn whose door opened (also
  after a lift), and self_closes counts only a close while a mask was
  active. A lift is logged, with no counter of its own. ladder-nodoor,
  detect, nudge and slap keep 1.2.3's semantics. (code)
• Known residual (code, from the release review): a budget point reached by
  the 64-token stretches (no counted line) decides on the last counted
  share. A loop the detector cannot count (lines of 20 characters or less, or
  no newline) after a varied stretch can therefore be lifted rather than
  escalated and run on to the token cap, with the masks off, so the model
  can still end the turn. 1.2.4 held the masks in that case.
• A ladder whose closer has no id lifts at the slap point — on a
  vocabulary whose closer is text the slap has nothing to force; the ladder
  now lifts the door there instead of holding the masks. No served model is
  affected (their closers are single tokens). (code)
• One opener check for chat and completions — whether a rendered or raw
  prompt ends inside an open think block is decided by one helper on the
  shared tag table (every family when the artifact sets the extended tags,
  the default family otherwise); no literal tag is left in the handlers, and
  the chat path sets the extended flag before the check. The served templates'
  result is unchanged, which a test pins. (code)
• door mode's budget — door is the mask alone and has no nudge or slap,
  so a mask could hold a turn to the cap on its own. After door_grace + grace counted lines without a close, the door lifts its masks (the
  multi-newline ids and the turn-ending ids it added) and says so once in the
  log; the turn continues unguarded, as with the switch off. No new response
  key, and a later detection does not reopen the lifted mask. (code)
• Door counters measure the sampled candidate set — door_masked and
  door_eog_masked count a step when a masked id would have been a candidate
  of the draw. candidate is now the set the draw actually samples from, after
  the row's truncation (top-k, top-p, min-p), for every top_k value: at
  top_k 0 a top-p cutoff could exclude a finite masked logit and the old
  code still counted it against the whole row. Observability only: the draw is
  byte-identical, which a fixed-seed test pins. (code)
• The door's budget advances by tokens — the budget counted ended lines
  only. loop_observe_ never ends a line without a newline and past its line
  cap it truncates and keeps the line open, so a model that switched to
  newline-free text never advanced the budget and the masks could again hold
  the turn to the cap. Each stretch of 64 generated tokens with no counted
  line now counts as one line-equivalent for the door's budget only — never
  for the detector's window. 64 is conservative against the 15–25 tokens a
  counted line costs, so a turn with lines keeps the line budget exactly.
  (code)
• A lifted door is not reopened — in door mode the budget's lift is
  latched: a later detection leaves the masks off and the door counters do not
  grow (the round-1 mutant that deleted the latch survived; the test now reds
  with it deleted). The door's grace also starts at its opening, so a reopened
  door cannot inherit a spent budget. (code)
• A stop string splitting a tag keeps the tag's id — a stop string that
  begins with the last bytes of the closer's text splits the closer's piece;
  the released first part carries no id (ordinary text), and the id rides on
  the part that stays held. Before, the held tail reached the tracker with id
  -1, so the block stayed open and the answer came back as reasoning (1.2.2's
  residual). Residual: the closer's released first part is text, so it shows at
  the end of reasoning_content; the block closes and the answer is clean.
  Avoiding it needs a stop matcher that knows the tags. (code)
• Streaming drops the line breaks after the closer — the non-streaming
  split (the reference) dropped them; the streamer kept them, so the two paths
  disagreed on the same token stream. The streamer now drops leading line
  breaks at the content's start, and only there: a reply with no block keeps
  its content as generated. (code)
• The positional id fallback refuses a lossy pairing — the flattened
  open/close id lists are id sets; the backend drops a role's -1 entry, so an
  id's index stops being its tag pair's index and zipping the two lists paired
  an opener with another family's closer. The zip now only builds when every
  pair contributed both ids, otherwise no pairing is built; the per-pair field
  is the lossless source. (code)
• The detector and a closer in one piece — on text-fallback vocabularies
  the detector ran before the closer check: a piece that carried a counted
  line and then the closer tripped the ladder and closed in the same call, so
  the nudge landed in the answer. Only the bytes before a completing closer go
  to the detector, and a detection or escalation on that line is counted but
  does not act. (code)
• The slap forces the open family's closer — its fallback forced the
  flattened first close id, i.e. another tag family's closer, when an extended
  pair had been opened by text. The slap now forces the closer of the family
  that is open, or none when that family's closer is text. (code)
• /v1/completions gets the chat path's start state — a raw prompt that
  ends inside an open block starts the turn in the block, so the masks and the
  loop guard watch it from the first sample; before, completions always started
  undecided and such a turn ran unwatched. (code)
• Dead branch and log wording — loop_on_detect_'s content branch was
  dead (its only caller passes false; the content phase aborts elsewhere) and
  is gone with its parameter. The loop-guard log lines said "lane:" without a
  lane number; the sampler does not know the lane, so the word is gone.
  (code)
• Clean-up, no behaviour change — the dead inclusive parameter of the
  two door counters removed, the unread id dropped from the stored masked
  logits, one helper for the closer-strip warn/latch, the counter list in
  handlers.cpp in one place, the n == 0 draw spends the counters like the
  greedy path, and loop_guard_door_ladder reads the door branches instead of
  loop_guard_is_ladder carrying a second invisible condition. (code)
• The loop_guard object on the wire — loop_guard_json returns a plain
  json instead of an ordered_json: the response body is a plain json, so
  the keys already landed alphabetically and the "last key" test checked a
  property no client saw. The order test is replaced by one on the object as
  it goes out: the serialized non-streaming response and the stream's finish
  frame each carry all seven keys with their values. No change for clients.
  (code)
• Tools — tools/clean_turns_gate.py sends each arm's temperature (it
  only printed it, so both arms ran at the unit's default row). The speaker
  similarity tool tools/tts_voice_sim.py has a clean-room ECAPA-TDNN head,
  tools/speaker_head.py, written from a behavioural specification and the
  paper; the tool is Apache-2.0 again (it carried a CC BY-SA 3.0
  transcription), and its gate number is unchanged: 0.598038 over the 46
  clips, the cross pair 0.262419 (measured-here). THIRD_PARTY.md records
  both the recipe and the checkpoint's licence.

Runtime: llama.cpp 3e4dfa8 with contrib/llama.cpp/patches (60
patches), unchanged from 1.2.4; dependencies unchanged. arcint-stt (1.2.0)
and arcint-imggen (1.1.1) are unchanged.

Release check (measured-here, 2026-10-25, the pre-tag package): the
device-free suite 329 cases and ctest -L unit 6/6, the package build's tests;
the branch's mutations red (each new test against its named mutation). The
Flash-Next speed A/B against 1.2.4 (the B60, IQ3_XXS with the served check's
flags, 4 rounds, twice) failed the gate as written, both times on decode:
first on spread (the one slow run, 37.3 t/s, was the one run with a
different answer), then on speed, 38.52 against 38.05 t/s (38.50 against
38.10 on the runs with the same answer); prefill equal in both (618.4 /
618.8 and 618.3 / 618.6 t/s). The decode split of four more runs, old / new /
old / new: the sampler 0.03 s an answer on both binaries, draft acceptance
65.2-65.8 % and 116-117 verifies on both, the difference in the GPU verify
time, and the old binary's own runs spanning 37.7-38.3 t/s against the new
binary's 37.9-38.0. Read as run-to-run variation of the forward, not a cost of
the release's code; the operator accepted the 1 % (2026-10-25). The guard's
budget and lift are unit-tested only, not run on the card.

Published (2026-10-25): arcint 1.2.5-1 built by its recipe from the
v1.2.5 tag tarball (sha256 acfa0516…) and published to the trixie
repository (index verified); installed from the pool on the card host, where
the coder (--loop-guard ladder) and the agent run it and answer the
stop-string check, the streamed answer now without the line breaks after the
closer. arcint-stt stays at 1.2.0-1, arcint-imggen at 1.1.1-1.