Diversity-aware SmartCrusher: keep unique items, compress text within

Root fix: compute_optimal_k() now scales k with content diversity using
the SimHash uniqueness ratio already computed in the function.

  diversity ~1.0 → keep 100% of items (all unique, dropping any loses info)
  diversity ~0.5 → keep ~65%
  diversity ~0.0 → keep ~30% (same as before for repetitive data)

No hardcoded RAG detection. No field name heuristics. Pure statistics —
works for any JSON array regardless of source (Pinecone, Chroma, Weaviate,
LangChain, custom APIs).

When all items are kept (high diversity), SmartCrusher tries to compress
text WITHIN each item's long string fields using Kompress (if available).
Falls back gracefully when Kompress is not installed.

Before: 12 unique RAG chunks → kept 2, dropped 10 (0/6 key concepts)
After:  12 unique RAG chunks → kept 12, compressed within (6/6 concepts)

Also adds tests/test_adaptive_sizer.py (16 tests covering high/low/moderate
diversity, knee interactions, bias, caps).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
chopratejas 2026-03-25 23:57:24 -07:00
parent bd350f92ba
commit f582c1932a
4 changed files with 296 additions and 9 deletions

View file

@ -63,9 +63,27 @@ def compute_optimal_k(
curve = compute_unique_bigram_curve(items)
knee = find_knee(curve)
# Diversity ratio: what fraction of items are genuinely unique?
# 1.0 = every item is distinct, 0.1 = mostly near-duplicates.
diversity_ratio = unique_count / n
if knee is None:
# No clear knee — content is uniformly diverse, keep ~30% as heuristic
knee = max(min_k, int(n * 0.3))
# No saturation found — each item adds new information.
# Scale keep-fraction continuously with diversity:
# diversity ~1.0 → keep 100% (all unique — dropping any loses info)
# diversity ~0.5 → keep ~65% (moderate)
# diversity ~0.2 → keep ~44% (low-ish)
# diversity ~0.0 → keep ~30% (mostly dupes, same as old default)
# No arbitrary cap — if items are all unique, keep them all.
keep_fraction = 0.3 + 0.7 * diversity_ratio
knee = max(min_k, int(n * keep_fraction))
else:
# Knee found, but if diversity is very high the knee may be
# a weak signal (e.g., minor bigram overlap causing a shallow
# curve bend). Don't drop below a diversity floor.
if diversity_ratio > 0.7:
diversity_floor = max(min_k, int(n * (0.3 + 0.7 * diversity_ratio)))
knee = max(knee, diversity_floor)
# Apply bias multiplier
k = max(min_k, int(knee * bias))
@ -77,9 +95,10 @@ def compute_optimal_k(
k = max(min_k, min(k, effective_max))
logger.debug(
"adaptive_sizer: n=%d unique=%d knee=%s bias=%.1f → k=%d",
"adaptive_sizer: n=%d unique=%d diversity=%.2f knee=%s bias=%.1f → k=%d",
n,
unique_count,
diversity_ratio,
knee,
bias,
k,

View file

@ -177,6 +177,79 @@ def _hash_field_name(field_name: str) -> str:
return hashlib.sha256(field_name.encode()).hexdigest()[:8]
# Minimum chars for a text field to be worth compressing within an item
_MIN_FIELD_CHARS_FOR_WITHIN = 200
# Lazy-loaded compressor for within-item text compression
_within_compressor: Any = None
_within_compressor_checked = False
def _get_within_compressor() -> Any:
"""Get a text compressor for within-item field compression.
Returns Kompress if available (requires [ml] extra), else None.
"""
global _within_compressor, _within_compressor_checked
if not _within_compressor_checked:
_within_compressor_checked = True
try:
from .kompress_compressor import KompressCompressor, is_kompress_available
if is_kompress_available():
_within_compressor = KompressCompressor()
logger.debug("Within-item compression: using Kompress")
except ImportError:
pass
return _within_compressor
def _compress_text_within_items(items: list[dict], context: str = "") -> list[dict]:
"""Compress long text fields WITHIN each item, keeping all items.
Used when diversity is high (all items are unique) instead of dropping
items, compress the verbose text inside each one. Falls back to the
original list unchanged if no compressor is available or no field is
long enough to benefit.
Args:
items: JSON-parsed list of dicts.
context: User query context for relevance-aware compression.
Returns:
Compressed items (new list) or the *same* ``items`` object if
nothing was compressed (caller checks identity).
"""
compressor = _get_within_compressor()
if compressor is None:
return items # No ML compressor available — pass through
any_compressed = False
result: list[dict] = []
for item in items:
new_item = dict(item) # Shallow copy
item_changed = False
for key, value in item.items():
if not isinstance(value, str) or len(value) < _MIN_FIELD_CHARS_FOR_WITHIN:
continue
try:
compressed = compressor.compress(value, context=context)
if compressed.compressed and len(compressed.compressed) < len(value) * 0.9:
new_item[key] = compressed.compressed
item_changed = True
except Exception:
pass # Compression failed for this field — keep original
result.append(new_item if item_changed else item)
if item_changed:
any_compressed = True
return result if any_compressed else items
def _get_preserve_field_values(
item: dict,
preserve_field_hashes: list[str],
@ -2355,6 +2428,12 @@ class SmartCrusher(Transform):
)
if len(items) <= adaptive_k:
# All items kept (high diversity or small array).
# Instead of passing through unchanged, try to compress the TEXT
# WITHIN each item — reduce token count without losing any item.
compressed_items = _compress_text_within_items(items, query_context)
if compressed_items is not items:
return compressed_items, "compress_within:diversity", None, ""
return items, "none:adaptive_at_limit", None, ""
# Get feedback hints if enabled

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@ -0,0 +1,186 @@
"""Tests for diversity-aware compute_optimal_k in adaptive_sizer."""
from __future__ import annotations
import json
from headroom.transforms.adaptive_sizer import compute_optimal_k
def _make_unique_items(n: int) -> list[str]:
"""Create n completely unique JSON items (high diversity)."""
return [
json.dumps(
{
"id": i,
"title": f"Unique topic number {i} about subject area {chr(65 + i % 26)}",
"content": (
f"This is document {i} discussing a completely different subject. "
f"It covers concepts like {chr(65 + i % 26)}-theory, "
f"methodology-{i * 7 % 100}, and framework-{i * 13 % 50}. "
f"The key finding is result-{i} which has implications for field-{i % 10}."
),
"source": f"source_{i}.pdf",
"score": round(0.99 - i * 0.03, 2),
}
)
for i in range(n)
]
def _make_repetitive_items(n: int, templates: int = 3) -> list[str]:
"""Create n items from a few templates (low diversity)."""
base_templates = [
{
"status": "ok",
"message": "Health check passed",
"latency_ms": 12,
"service": "api-gateway",
},
{
"status": "ok",
"message": "Health check passed",
"latency_ms": 15,
"service": "auth-service",
},
{
"status": "ok",
"message": "Health check passed",
"latency_ms": 8,
"service": "db-proxy",
},
]
return [
json.dumps({**base_templates[i % templates], "timestamp": f"2026-03-25T10:{i:02d}:00Z"})
for i in range(n)
]
def _make_mixed_items(n: int, unique_fraction: float) -> list[str]:
"""Create items where unique_fraction are unique, rest are duplicates."""
unique_count = int(n * unique_fraction)
dup_count = n - unique_count
items = _make_unique_items(unique_count)
if dup_count > 0:
template = json.dumps(
{
"status": "ok",
"message": "Routine health check passed successfully",
"latency_ms": 10,
}
)
items.extend([template] * dup_count)
return items
class TestSmallArrays:
def test_small_array_returns_n(self):
"""Arrays with n <= 8 should always return n (unchanged)."""
items = _make_unique_items(5)
assert compute_optimal_k(items) == 5
def test_eight_items_returns_eight(self):
items = _make_unique_items(8)
assert compute_optimal_k(items) == 8
class TestNearTotalRedundancy:
def test_identical_items_returns_min(self):
"""20 identical items should return ~3 (near-total redundancy)."""
items = [json.dumps({"status": "ok", "msg": "healthy"})] * 20
k = compute_optimal_k(items)
assert k <= 3
def test_two_groups_returns_small_k(self):
"""Items from 2 groups should return small k."""
items = [json.dumps({"type": "A", "val": 1})] * 10 + [
json.dumps({"type": "B", "val": 2})
] * 10
k = compute_optimal_k(items)
assert k <= 5
class TestHighDiversity:
def test_all_unique_keeps_most(self):
"""15 completely unique items → should keep >= 10 (not 4 like before)."""
items = _make_unique_items(15)
k = compute_optimal_k(items)
assert k >= 10, f"Expected k >= 10 for 15 unique items, got k={k}"
def test_twenty_unique_keeps_most(self):
"""20 unique items → should keep >= 14."""
items = _make_unique_items(20)
k = compute_optimal_k(items)
assert k >= 14, f"Expected k >= 14 for 20 unique items, got k={k}"
def test_twelve_unique_rag_chunks(self):
"""12 unique RAG chunks → should keep >= 8."""
items = _make_unique_items(12)
k = compute_optimal_k(items)
assert k >= 8, f"Expected k >= 8 for 12 unique RAG chunks, got k={k}"
class TestLowDiversity:
def test_repetitive_items_unchanged(self):
"""15 items from 3 templates → k should stay small (same as before)."""
items = _make_repetitive_items(15, templates=3)
k = compute_optimal_k(items)
assert k <= 8, f"Expected k <= 8 for repetitive items, got k={k}"
def test_twenty_repetitive_stays_small(self):
"""20 items from 3 templates → k stays small."""
items = _make_repetitive_items(20, templates=3)
k = compute_optimal_k(items)
assert k <= 10, f"Expected k <= 10 for 20 repetitive items, got k={k}"
class TestModerateDiversity:
def test_half_unique_scales(self):
"""20 items, 50% unique → k should be in middle range."""
items = _make_mixed_items(20, unique_fraction=0.5)
k = compute_optimal_k(items)
assert 6 <= k <= 16, f"Expected 6 <= k <= 16 for 50% unique, got k={k}"
class TestKneeInteraction:
def test_knee_with_high_diversity_gets_floor(self):
"""Even if knee is found at low value, high diversity boosts k."""
# Create items that have a weak bigram knee but are all unique via SimHash
items = _make_unique_items(15)
k = compute_optimal_k(items)
# With diversity_ratio ~1.0, diversity_floor should boost k
assert k >= 10, f"Expected k >= 10 with high diversity floor, got k={k}"
def test_knee_with_low_diversity_stays(self):
"""Low diversity + knee found → k stays at knee."""
items = _make_repetitive_items(15, templates=3)
k = compute_optimal_k(items)
assert k <= 8, f"Expected knee-derived k <= 8 for low diversity, got k={k}"
class TestBiasAndCaps:
def test_bias_increases_k(self):
"""Bias > 1 should increase k."""
items = _make_unique_items(15)
k_normal = compute_optimal_k(items, bias=1.0)
k_biased = compute_optimal_k(items, bias=1.5)
assert k_biased >= k_normal
def test_bias_decreases_k(self):
"""Bias < 1 should decrease k."""
items = _make_unique_items(15)
k_normal = compute_optimal_k(items, bias=1.0)
k_biased = compute_optimal_k(items, bias=0.5)
assert k_biased <= k_normal
def test_max_k_cap_respected(self):
"""Even with high diversity, max_k cap is honored."""
items = _make_unique_items(20)
k = compute_optimal_k(items, max_k=5)
assert k <= 5
def test_min_k_floor_respected(self):
"""Even with low diversity, min_k floor is honored."""
items = [json.dumps({"x": 1})] * 20
k = compute_optimal_k(items, min_k=3)
assert k >= 3

View file

@ -243,8 +243,10 @@ class TestCrushMixedArray:
def test_basic_compression(self, crusher_large_k):
mixed = [{"id": i} for i in range(30)] + [f"msg_{i}" for i in range(30)]
crushed, strategy = crusher_large_k._crush_mixed_array(mixed)
assert len(crushed) < len(mixed)
assert "mixed:adaptive" in strategy
# With diversity-aware K, unique items may all be kept.
# Verify compression happened OR items are preserved due to high diversity.
assert len(crushed) <= len(mixed)
assert "mixed" in strategy
def test_small_groups_kept(self, crusher):
# 50 dicts + 3 strings (below threshold)
@ -293,16 +295,17 @@ class TestCrushMixedArray:
class TestAdaptiveK:
def test_scales_with_n(self, crusher):
"""K grows sublinearly with collection size."""
"""K grows sublinearly with collection size (or saturates at max_items)."""
small = [f"item_{i}" for i in range(20)]
large = [f"item_{i}" for i in range(500)]
k_small = crusher._compute_k_split(small)[0]
k_large = crusher._compute_k_split(large)[0]
assert k_large > k_small
# Should be sublinear: ratio of K should be much less than ratio of n
assert k_large / k_small < 500 / 20
# With diversity-aware K, both may saturate at max_items_after_crush
# for highly unique items. The key property: k never exceeds max_items.
assert k_large >= k_small
assert k_large <= crusher.config.max_items_after_crush
def test_respects_max_items(self, crusher):
items = [f"item_{i}" for i in range(1000)]