55a26c9983
is_repetition_dominated is tuned for the truncated-continuation nudge, where a false positive merely skips a continuation. At the interrupt checkpoints the same verdict DROPS the partial from history and tells the model the reply degenerated, so a legitimately repetitive but correct reply - twelve distinct INSERT rows sharing a long prefix trip the 60-char window scan - was erased and mislabelled. Gate the two checkpoints on is_runaway_repetition: dominated AND, when the text has line structure, at most half of its non-empty lines distinct. Byte-identical repeated lines (the #112764 shape) still qualify; distinct batch rows no longer do. The continuation path keeps the looser predicate. The plain interrupt site now mirrors the redirect placeholder (empty content, display_kind=hidden, api_content=[response interrupted]) so the bracketed placeholder no longer surfaces as an assistant bubble in transcript replays.
89 lines
4.2 KiB
Python
89 lines
4.2 KiB
Python
"""Cheap content-sanity checks for the truncated-response continuation path.
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A model in a degenerate repetition loop can spend its ENTIRE output budget echoing one fragment;
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the ``finish_reason=length`` continuation would then stitch it into the final response with a
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"continue" nudge (one incident: a 60k-char turn delivered as 31 Discord messages). This detects
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repetition-dominated fragments BEFORE the nudge so the turn aborts with a clear error. Deliberately
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conservative: only LONG verbatim repeats (60+ chars) covering a majority of the fragment trip it.
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"""
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from __future__ import annotations
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import math
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from collections import Counter
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# Below this length the check doesn't run: short truncations trivially
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# contain repeated tokens and are legitimately continued.
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MIN_FRAGMENT_LENGTH = 400
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# Exact-repeat window; far beyond ordinary phrasing reuse (citations, headings, similar code).
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_REPEAT_WINDOW = 60
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# A window repeating at least this often is a signal even for short fragments.
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_MIN_REPEAT_COUNT = 5
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# "Repetition-dominated" = repeated windows cover at least this fraction.
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_DOMINANCE_RATIO = 0.5
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# What an interrupt checkpoint says INSTEAD of a repetition-dominated partial. Replaying the
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# looped bytes (as the redirect's api_content or as the interrupted assistant row) re-seeds the
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# loop on the next request and the corruption survives restarts (#112764); the model only needs
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# to know the reply degenerated and was cut off.
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REPETITION_LOOP_INTERRUPTED = "[the reply degenerated into a repetition loop and was interrupted]"
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# ``is_runaway_repetition``: a multi-line partial must be mostly copies of a few lines. Batch-style
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# output (distinct INSERT rows, similar table rows) shares long prefixes and trips the window
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# scan, but every line is distinct; a loop re-emits the same line(s).
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_RUNAWAY_DISTINCT_LINE_RATIO = 0.5
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def is_repetition_dominated(text: str) -> bool:
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"""True when a single 60+ char substring recurs often enough to cover at least half
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of ``text`` — the signature of a repetition loop. Fail-open for non-string/short input.
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That shape is the signature of a model repetition loop (issue #86581), and continuing such a fragment is
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pointless — the continuation nudge would just stitch more repeated text into the final response.
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"""
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if not isinstance(text, str):
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return False
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n = len(text)
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if n < MIN_FRAGMENT_LENGTH:
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return False
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# Fast path: one normalized line duplicated enough to cover half the fragment (the common echo shape).
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if _line_repetition_dominated(text, n):
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return True
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# General path: fixed-size windows sliding one char at a time, catching loops that
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# don't align to line boundaries. A window must appear ``needed`` times to cover
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# >= _DOMINANCE_RATIO (and >= _MIN_REPEAT_COUNT).
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window = _REPEAT_WINDOW
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needed = max(_MIN_REPEAT_COUNT, math.ceil(n * _DOMINANCE_RATIO / window))
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counts: dict[str, int] = {}
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for i in range(n - window + 1):
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key = text[i : i + window]
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c = counts.get(key, 0) + 1
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if c >= needed:
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return True
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counts[key] = c
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return False
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def is_runaway_repetition(text: str) -> bool:
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"""Stricter than :func:`is_repetition_dominated`: also require the runaway shape.
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An interrupt checkpoint DROPS the partial when this fires, so a legitimately repetitive but
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correct reply (distinct batch rows) must not qualify: repeated windows have to dominate AND,
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when the text has line structure, at most half of its non-empty lines may be distinct.
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"""
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if not is_repetition_dominated(text):
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return False
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lines = [line.strip() for line in text.splitlines()]
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lines = [line for line in lines if line]
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if len(lines) < _MIN_REPEAT_COUNT:
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return True # no line structure to judge by: a dominated single-line loop
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return len(set(lines)) <= len(lines) * _RUNAWAY_DISTINCT_LINE_RATIO
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def _line_repetition_dominated(text: str, n: int) -> bool:
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"""True when a single normalized line covers half the fragment via repeats."""
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counts = Counter(norm for norm in (line.strip() for line in text.splitlines()) if norm)
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return any(c >= _MIN_REPEAT_COUNT and c * len(line) >= n * _DOMINANCE_RATIO for line, c in counts.items())
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