headroom/benchmarks/i18n_compression_eval.py
Zhenjia ZHOU 4035c04187
feat(text-crusher): CJK-aware segmentation + relevance via ICU (#1504)
## Description

`TextCrusher` (the native extractive prose compressor added in #1171)
only handled ASCII: `split_segments` split on `.!?`+whitespace and
`tokens` split on whitespace/alphanumeric runs. CJK
(Chinese/Japanese/Korean) has neither spaces nor ASCII terminators, so a
whole CJK paragraph collapsed into **one segment / one token** — it
passed through at ~0% compression, and BM25 relevance + salience scored
zero terms.

This makes `TextCrusher` CJK-aware. CJK-bearing content takes an ICU
(`icu_segmenter`, UAX#29 sentence + dictionary word) segmentation path,
with a length fallback for terminator-sparse runs, a local BM25 over the
ICU word tokens, and ICU-token salience. Dispatch is on **content
only**, so pure-ASCII text is byte-identical to before — the shared
`BM25Scorer` and the ASCII path are untouched.

It also adds a committed, reproducible answer-retention eval
(`benchmarks/i18n_compression_eval.py`) with a deterministic zh/ja/ko CI
regression gate, so the improvement below is permanently verifiable
rather than a one-off measurement.

Extends #1171.

## Type of Change

- [x] Bug fix (CJK passed through near-uncompressed)
- [x] New feature (CJK segmentation / relevance support)
- [x] Performance improvement (CJK now compresses; ICU segmenters
cached, not rebuilt per call)

## Changes Made

- `is_cjk` predicate gates a CJK path (ideographs, kana, Hangul, CJK
punctuation, full/half-width forms).
- `split_segments` → ICU `SentenceSegmenter` for CJK + a mandatory
length fallback (whitespace / CJK punctuation / hard cap) for
terminator-sparse runs; ASCII path unchanged.
- `tokens` → ICU `WordSegmenter` (dictionary) for CJK; ASCII path
unchanged.
- `relevance_cjk`: a local BM25 over ICU word tokens — the shared ASCII
`BM25Scorer` scores zero terms for CJK and is parity-locked, so this is
an intentional separate scorer (documented in code).
- CJK salience uses ICU tokens (whitespace-split gave one giant "word" →
zero salience).
- `count_tokens`: CJK-aware so `compression_ratio` isn't nonsense for
space-free text.
- ICU segmenters resolved once in `static LazyLock` (compiled_data is
static) instead of rebuilt per call.
- New dep `icu_segmenter` 2.2, `compiled_data` only (see Dependency
below).
- `benchmarks/i18n_compression_eval.py` +
`tests/test_transforms/test_text_crusher_cjk_eval.py`: a zh/ja/ko
answer-retention eval — a deterministic needle CI gate (always-runs, no
external data), real-transcript fidelity with CJK-aware salient, and
optional `multi-wiki-qa` natural-data retention (loaded via the
`[evals]` `datasets` extra, skipped if absent; data never vendored —
CC-BY-NC-SA).

## Testing

- [x] Unit tests pass (`pytest` + `cargo test`)
- [x] Linting passes (`ruff check`/`format` on the new eval + test —
clean)
- [ ] Type checking passes (`mypy headroom`) — N/A, the only Python
added is a benchmark + test, not `headroom/` source
- [x] New tests added for new functionality
- [x] Manual testing performed (see Real Behavior Proof)

### Test Output

```text
$ cargo test -p headroom-core --lib text_crusher
running 12 tests
test result: ok. 12 passed; 0 failed; 0 ignored; 0 measured; 841 filtered out

$ .venv/bin/python -m pytest tests/test_transforms/test_text_crusher*.py
15 passed

$ .venv/bin/python -m pytest tests/test_transforms/test_text_crusher_cjk_eval.py
6 passed   # deterministic zh/ja/ko needle CI gate

$ cargo clippy -p headroom-core && ruff check benchmarks/i18n_compression_eval.py   # both clean
```

## Real Behavior Proof

- Environment: macOS (Darwin 25.3.0), Python in a uv venv,
`headroom-core` built via `uv pip install -e .` (maturin), branch
`feat/cjk-text-compression`.
- Exact command / steps: built `_core`, then ran a mixed
Chinese+Japanese doc (no spaces, `。` terminators) through
`TextCrusher().compress(doc, "认证令牌缓存策略", 0.3)`; separately evaluated
answer-retention on the public CMRC2018 Chinese QA dev set (bury the
gold-answer paragraph among 25 distractors, query = the question,
compress to 30%, check the gold answer survives), and end-to-end through
`ContentRouter`.
- Observed result: a mixed Chinese+Japanese doc compressed 189 → 78
tokens (ratio 0.41, kept 3/8 segments) with the query-relevant sentence
surviving — before this change the same doc was a single segment → 100%
passthrough. On the public CMRC2018 Chinese QA dev set, answer-retention
under 30% compression rose 34% → 93% (multiple seeds). End-to-end
through `ContentRouter` on real CJK content, aggregate savings rose 16%
→ 40%. Pure-ASCII (English) output stayed byte-identical (the English
parity fixtures did not move). Demo terminal output:

    ```text
    ORIGINAL  tokens= 189  chars=189
    COMPRESS  tokens=  78  ratio=0.41  segments kept 3/8
    QUERY-RELEVANT sentence survived: True
    --- compressed output (verbatim kept CJK sentences) ---
    认证令牌的缓存策略采用最近最少使用淘汰算法来管理过期条目。
    请求重试使用指数退避并设置最大次数上限。
    数据备份每天凌晨执行并保留最近三十天的快照。
    ```
The committed eval now demonstrates this across all three CJK languages.
The deterministic needle gate (in CI via
`tests/test_transforms/test_text_crusher_cjk_eval.py`, 6 passed) has
TextCrusher keep the query-relevant needle while truncate/random drop it
in zh, ja, and ko. On real `multi-wiki-qa` natural data (n=80/lang),
query-aware answer-retention is **zh 74% / ja 70% / ko 50%** vs
**25–41%** for the truncate/random baselines:

    ```text
=== Part A: multi-wiki-qa answer-retention (n=80/lang, target_ratio=0.3)
===
      lang    text_crusher  truncate  random
      zh-cn           74%       25%     38%
      ja              70%       31%     39%
      ko              50%       26%     41%
    ```
Korean is measurably weaker (ICU has no Korean dictionary and falls back
to UAX#29 word-breaking) — still well above baselines, and scoped as a
follow-up.
- Not tested: the live proxy HTTP path (validated at the `ContentRouter`
/ `TextCrusher` layer, not via a running proxy); no-space Korean
(standard Korean is space-delimited and is covered); non-CJK SE-Asian
scripts (out of scope).

## Dependency (per CONTRIBUTING supply-chain policy)

`icu_segmenter` 2.2 (ICU4X), `features = ["compiled_data"]`:

- **Why this package (vs. ourselves / existing deps):** CJK needs
dictionary/UAX#29 segmentation. A hand-rolled char-bigram scored
slightly worse on real data (CMRC2018 answer-retention: 92.5% ICU vs 91%
bigram, 4 seeds); jieba/lindera are ZH-only or 13–207 MB dicts. ICU4X
covers zh/ja/ko in one crate. The existing `unicode-segmentation` does
UAX#29 only (no CJK dictionary), so it can't word-segment space-free
CJK.
- **Who maintains it:** the official `unicode-org` ICU4X project; active
release cadence (2.2 in 2025); no known CVEs.
- **Install surface:** ~13 new pure-Rust crates, no build scripts, no
native code, no build/runtime network. `compiled_data` bundles locale
data at compile time (hermetic). `auto`/`lstm` deliberately NOT enabled
— LSTM covers SE-Asian scripts (Thai/Lao), not CJK, and would pull in
`libm` for nothing.
- **Why this version:** 2.x is the stabilized ICU4X API (1.x used a
different data-provider model); floored at 2.2 (Cargo.lock pins the
patch) since segmenter boundaries are observable in output and bumps
should be deliberate.

## Review Readiness

- [x] I have performed a self-review
- [x] This PR is ready for human review

## Checklist

- [x] My code follows the project's style guidelines
- [x] I have performed a self-review of my code
- [x] I have commented my code, particularly in hard-to-understand areas
- [x] I have made corresponding changes to the documentation (CHANGELOG)
- [x] My changes generate no new warnings (clippy + fmt clean)
- [x] I have added tests that prove my feature works
- [x] New and existing unit tests pass locally with my changes
- [x] I have updated the CHANGELOG.md

## Additional Notes

- **Parity:** the shared `BM25Scorer` (byte-exact parity-locked with
`headroom/relevance/bm25.py`) is untouched. `relevance_cjk` is a
separate local scorer because the shared one's tokenizer is ASCII-only.
The whole CJK path lives in Rust (`text_crusher.py` is a thin wrapper
over `_core`), so there is no Python mirror to keep in sync; the parity
fixtures stay green (only the CJK `unicode` fixture was re-recorded,
intentionally; English fixtures unchanged).
- **Known by-design gap (not a bug):** CJK content + a pure-ASCII query
yields no token overlap, so relevance falls back to recency + salience
(cross-script query matching is unsupported).
- The Python added is a benchmark
(`benchmarks/i18n_compression_eval.py`) plus its test, not `headroom/`
runtime source — both are `ruff`-clean; `mypy headroom` is unaffected.
- **License:** the optional Part A pulls `alexandrainst/multi-wiki-qa`
(CC-BY-NC-SA-4.0) at run time via the `[evals]` extra and is skipped if
absent — the dataset is never vendored into the repo, and the always-run
CI gate (Part C) uses only our own deterministic data.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-15 19:58:48 +00:00

282 lines
10 KiB
Python

#!/usr/bin/env python3
"""i18n compression-quality eval (zh/ja/ko): does extractive compression keep
the answer-bearing content in CJK? No LLM/API calls -- fully local.
Part C -- our own DETERMINISTIC needle answer-retention (zh/ja/ko): the always-
runs regression gate. A distinctive needle sentence is buried (in the middle) in
language-matched distractor sentences; compress query-aware; assert the needle
survives. No external data. TextCrusher (query-aware) vs truncate (keep-recent)
vs random baselines.
Part B -- real-transcript fidelity with CJK-aware salient: optional, anonymized.
Part A -- natural-data answer-retention on alexandrainst/multi-wiki-qa
(zh-cn/ja/ko): optional, via the [evals] datasets extra, skipped if absent.
Usage: python benchmarks/i18n_compression_eval.py [transcript.jsonl]
"""
from __future__ import annotations
import glob
import os
import random
import re
import sys
import time
from headroom.transforms.text_crusher import TextCrusher
_REDACT = [
(re.compile(r"/Users/[^/\s]+"), "/Users/USER"),
(re.compile(r"\b[\w.+-]+@[\w-]+\.[\w.-]+\b"), "EMAIL"),
(re.compile(r"\b(?:sk|pk|ghp|gho|xox[baprs])-[A-Za-z0-9_-]{10,}\b"), "TOKEN"),
(re.compile(r"\b[A-Fa-f0-9]{40,}\b"), "HEX"),
]
# Split on ASCII and full-width CJK terminators so baselines segment CJK too.
_SEG = re.compile(r"(?<=[.!?。!?])\s*|\n+")
_CJK_RUN = re.compile(r"[㐀-鿿぀-ヿ가-힯]+")
def anon(t: str) -> str:
for rx, rep in _REDACT:
t = rx.sub(rep, t)
return t
def norm(s: str) -> str:
# CJK has no spaces; drop all whitespace so substring match is robust.
return re.sub(r"\s+", "", s.lower())
def _segs(text: str) -> list[str]:
return [s for s in _SEG.split(text) if s.strip()]
def truncate_keep_last(text: str, ratio: float) -> str:
segs = _segs(text)
budget = int(sum(len(s) for s in segs) * ratio)
kept: list[str] = []
c = 0
for s in reversed(segs):
if c >= budget:
break
kept.append(s)
c += len(s)
return "".join(reversed(kept))
def random_keep(text: str, ratio: float, seed: int) -> str:
segs = _segs(text)
idx = list(range(len(segs)))
random.Random(seed).shuffle(idx)
budget = int(sum(len(s) for s in segs) * ratio)
kept: set[int] = set()
c = 0
for i in idx:
if c >= budget:
break
kept.add(i)
c += len(segs[i])
return "".join(segs[i] for i in sorted(kept))
# --- Part C: deterministic needle retention (zh / ja / ko) ---------------------
# Each needle carries a distinctive verbatim KEY that must survive. Distractors
# are generated (deterministic, distinct, topic-unrelated to the query) so the
# haystack is large enough to FORCE real compression -- the needle only survives
# under TextCrusher because it is query-relevant, not because of passthrough.
_NEEDLES = {
"zh": {
"query": "认证令牌缓存淘汰策略",
"key": "最近最少使用淘汰",
"needle": "认证令牌的缓存采用最近最少使用淘汰算法来管理过期条目。",
"distractor": lambda i: f"{i}号监控服务器的日志显示子系统{i}今天运行平稳没有出现异常。",
},
"ja": {
"query": "認証トークン キャッシュ 破棄 アルゴリズム",
"key": "最長未使用",
"needle": "認証トークンのキャッシュは最長未使用アルゴリズムで管理される。",
"distractor": lambda i: (
f"{i}番目の監視サーバーのログには{i}番のサブシステムが本日も正常に稼働したと記録されている。"
),
},
"ko": {
"query": "인증 토큰 캐시 제거 알고리즘",
"key": "최근 최소 사용",
"needle": "인증 토큰 캐시는 최근 최소 사용 알고리즘으로 관리된다.",
"distractor": lambda i: (
f"{i}번 모니터링 서버의 로그에는 {i}번 하위 시스템이 오늘도 정상 작동했다고 기록되어 있다."
),
},
}
def _haystack(spec: dict, n_distract: int = 24) -> str:
half = n_distract // 2
before = [spec["distractor"](i) for i in range(half)]
after = [spec["distractor"](i) for i in range(half, n_distract)]
# needle in the MIDDLE so keep-recent (truncate) reliably misses it.
return "".join(before + [spec["needle"]] + after)
def retention_synthetic(lang: str, ratio: float = 0.3, seed: int = 0) -> dict[str, bool]:
spec = _NEEDLES[lang]
hay = _haystack(spec)
key = norm(spec["key"])
tc = TextCrusher()
out_tc = tc.compress(hay, spec["query"], ratio).compressed
return {
"text_crusher": key in norm(out_tc),
"truncate": key in norm(truncate_keep_last(hay, ratio)),
"random": key in norm(random_keep(hay, ratio, seed)),
}
def eval_synthetic(ratio: float = 0.3) -> None:
print(f"\n=== Part C: synthetic needle retention (zh/ja/ko, target_ratio={ratio}) ===")
print(f" {'lang':5} {'text_crusher':>13} {'truncate':>9} {'random':>7}")
for lang in ("zh", "ja", "ko"):
r = retention_synthetic(lang, ratio)
print(
f" {lang:5} {str(r['text_crusher']):>13} {str(r['truncate']):>9} {str(r['random']):>7}"
)
print(" (needle must survive under TextCrusher; baselines are the contrast)")
# --- Part B: real CJK transcript fidelity (CJK-aware salient) ------------------
# ASCII salient (identifiers/numbers/errors) STILL matters in CJK coding context.
_SALIENT_ASCII = re.compile(
r"\b(?:error|exception|fail(?:ed|ure)?|warning|traceback|assert|todo|fixme)\b"
r"|\b[A-Z]{2,}\b|\b[A-Za-z_][A-Za-z0-9_]*\.[A-Za-z_][A-Za-z0-9_]*\b|\b\d+\b"
)
def _cjk_hapax(text: str) -> set[str]:
# distinctive CJK content = char-bigrams occurring exactly once (rare = must-keep)
grams: dict[str, int] = {}
for run in _CJK_RUN.findall(text):
for i in range(len(run) - 1):
g = run[i : i + 2]
grams[g] = grams.get(g, 0) + 1
return {g for g, c in grams.items() if c == 1}
def salient_set(text: str) -> set[str]:
return set(_SALIENT_ASCII.findall(text)) | _cjk_hapax(text)
def _block_texts(jsonl_path: str, min_chars: int, limit: int) -> list[str]:
import json
out: list[str] = []
with open(jsonl_path, encoding="utf-8") as fh:
for line in fh:
try:
o = json.loads(line)
except json.JSONDecodeError:
continue
c = (o.get("message") or {}).get("content")
parts = (
[c]
if isinstance(c, str)
else [
p["text"] for p in c if isinstance(p, dict) and isinstance(p.get("text"), str)
]
if isinstance(c, list)
else []
)
for t in parts:
if len(t) >= min_chars and _CJK_RUN.search(t): # CJK-bearing only
out.append(anon(t))
if len(out) >= limit:
break
return out[:limit]
def eval_transcript(
jsonl_path: str, ratio: float = 0.4, min_chars: int = 600, limit: int = 40
) -> None:
blocks = _block_texts(jsonl_path, min_chars, limit)
if not blocks:
print(
f"\n=== Part B: no CJK blocks >= {min_chars} chars in {os.path.basename(jsonl_path)} ==="
)
return
tc = TextCrusher()
ratios: list[float] = []
times: list[float] = []
retentions: list[float] = []
for b in blocks:
sal_before = salient_set(b)
t0 = time.perf_counter()
out = tc.compress(b, "", ratio).compressed
times.append((time.perf_counter() - t0) * 1000)
retentions.append(len(sal_before & salient_set(out)) / max(1, len(sal_before)))
ratios.append(len(out) / max(1, len(b)))
n = len(blocks)
print(
f"\n=== Part B: real CJK transcript fidelity (n={n}, anonymized, target_ratio={ratio}) ==="
)
print(f" mean char-ratio kept: {sum(ratios) / n:.2f}")
print(f" mean speed: {sum(times) / n:.1f} ms/block")
print(f" CJK-aware salient retention: {sum(retentions) / n:.1%}")
# --- Part A: optional natural-data retention (multi-wiki-qa zh/ja/ko) ----------
# Schema verified: row = {id, title, context, question, answers:{text:[...]}}.
# Answers are guaranteed verbatim substrings of the (long) context; CC-BY-NC-SA.
def eval_multiwiki(
langs=("zh-cn", "ja", "ko"), n: int = 80, ratio: float = 0.3, seed: int = 0
) -> None:
try:
from datasets import load_dataset
except ImportError:
print(
"\n=== Part A: `datasets` not installed; skipping (pip install headroom-ai[evals]) ==="
)
return
tc = TextCrusher()
print(f"\n=== Part A: multi-wiki-qa answer-retention (n={n}/lang, target_ratio={ratio}) ===")
print(f" {'lang':6} {'text_crusher':>13} {'truncate':>9} {'random':>7}")
for lang in langs:
try:
ds = load_dataset("alexandrainst/multi-wiki-qa", lang, split=f"train[:{n * 2}]")
except Exception as e: # noqa: BLE001 -- optional path, fail-open
print(f" {lang}: load failed ({e}); skipping")
continue
ex = []
for r in ds:
ans = r.get("answers")
a = ans["text"][0] if isinstance(ans, dict) and ans.get("text") else None
if r.get("context") and r.get("question") and a:
ex.append((r["context"], r["question"], a))
random.Random(seed).shuffle(ex)
ex = ex[:n]
hit = {"text_crusher": 0, "truncate": 0, "random": 0}
for ctx, q, ans in ex:
a = norm(ans)
hit["text_crusher"] += a in norm(tc.compress(ctx, q, ratio).compressed)
hit["truncate"] += a in norm(truncate_keep_last(ctx, ratio))
hit["random"] += a in norm(random_keep(ctx, ratio, seed))
m = max(1, len(ex))
print(
f" {lang:6} {hit['text_crusher'] / m:>12.0%} {hit['truncate'] / m:>9.0%} {hit['random'] / m:>7.0%}"
)
if __name__ == "__main__":
eval_synthetic()
tx = sys.argv[1] if len(sys.argv) > 1 else None
if tx is None:
found = glob.glob(os.path.expanduser("~/.claude/projects/*headroom*/*.jsonl"))
tx = max(found, key=os.path.getsize) if found else None
if tx and os.path.exists(tx):
eval_transcript(tx)
else:
print("\nno transcript jsonl found; skipping Part B")
eval_multiwiki()