headroom/tests/test_compression_units.py
Jervis 09c66ac212
fix(proxy): batch small Codex Responses tool outputs (#2239)
## Description

Batches small Codex/OpenAI Responses tool-output units through the
existing ContentRouter instead of skipping each unit individually below
the 512-byte floor. This fixes sessions where many small tool outputs
are collectively worth compressing, but no single output clears the
per-unit threshold.

The change keeps larger units on the existing independent compression
path, preserves CCR retrieval markers and protected tags across the
batch envelope, rejects structurally invalid batch output, and leaves
under-floor tails as size-floor passthroughs.

Fixes #2234

## Type of Change

- [x] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)

## Changes Made

- Added `headroom/transforms/compression_batches.py` for bounded
compatible-unit batching, batch envelope parsing, tag/CCR marker
preservation, and per-entry result splitting.
- Updated the OpenAI Responses compression adapter to batch small
tool-output text slots while keeping larger units on the existing cached
per-unit path.
- Switched the unit size floor to UTF-8 bytes so CJK and other multibyte
text are measured consistently with the byte threshold.
- Added regression coverage for batching, CJK byte floors, CCR marker
preservation, malformed batch rejection, array output parts, and
under-floor tails.

## Testing

- [x] Unit tests pass (`pytest`)
- [x] Linting passes (`ruff check`)
- [x] Type checking passes (`mypy`)
- [x] New tests added for new functionality
- [ ] Manual testing performed

### Test Output

```text
$ uv run --with pytest --with fastapi --with httpx --with anyio --with uvicorn --with h2 pytest tests/test_compression_batches.py tests/test_compression_units.py tests/test_openai_responses_compression_units.py -q
47 passed, 1 warning

$ uvx ruff==0.15.17 check headroom/proxy/handlers/openai.py headroom/transforms/compression_batches.py headroom/transforms/compression_units.py tests/test_compression_batches.py tests/test_compression_units.py tests/test_openai_responses_compression_units.py --output-format concise
All checks passed!

$ uvx ruff==0.15.17 format --check headroom/proxy/handlers/openai.py headroom/transforms/compression_batches.py headroom/transforms/compression_units.py tests/test_compression_batches.py tests/test_compression_units.py tests/test_openai_responses_compression_units.py
6 files already formatted

$ uv run --with mypy mypy headroom/transforms/compression_batches.py
Success: no issues found in 1 source file
```

## Real Behavior Proof

- Environment: Windows 11, Python 3.13.3, local checkout of this PR
branch.
- Exact command / steps: ran the focused batching/unit/OpenAI Responses
test suites above, including cases where four individually-small tool
outputs collectively exceed the shared floor and where output arrays
contain multiple text parts plus non-text parts.
- Observed result: small outputs are sent through one router call and
applied back to their original slots; under-floor tails remain
unmodified; non-text parts are preserved; CCR markers are retained or
the entire batch is rejected if moved/corrupted.
- Not tested: a live Codex Responses proxy session against an upstream
model; full-suite collection was not run locally.

## 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
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective
- [x] New and existing unit tests pass locally with my changes
- [ ] I have updated the CHANGELOG.md if applicable

---------

Co-authored-by: JerrettDavis <mxjerrett@gmail.com>
2026-07-15 19:57:50 +00:00

318 lines
9.3 KiB
Python

from __future__ import annotations
from headroom.transforms.compression_units import (
CompressionUnit,
RoutedCompressionUnit,
compress_unit_with_router,
compress_units_with_router,
)
from headroom.transforms.content_router import (
CompressionStrategy,
RouterCompressionResult,
)
class TokenCounter:
def count_text(self, text: str) -> int:
return len(text.split())
class Router:
def __init__(self, compressed: str):
self.compressed = compressed
def compress(self, content: str, **_kwargs):
return RouterCompressionResult(
compressed=self.compressed,
original=content,
strategy_used=CompressionStrategy.KOMPRESS,
)
class CharacterCounter:
def count_text(self, text: str) -> int:
return len(text)
def test_compression_unit_uses_utf8_bytes_for_floor():
result = compress_unit_with_router(
CompressionUnit(
text="" * 256,
provider="openai",
endpoint="responses",
role="tool",
item_type="function_call_output",
min_bytes=512,
),
router=Router(""),
tokenizer=CharacterCounter(),
)
assert result.modified is True
assert result.reason is None
def test_compression_unit_accepts_token_shrinking_replacement():
result = compress_unit_with_router(
CompressionUnit(
text="alpha beta gamma delta epsilon",
provider="openai",
endpoint="responses",
role="assistant",
item_type="message",
metadata={"compress_assistant": "true"},
min_bytes=1,
),
router=Router("alpha beta"),
tokenizer=TokenCounter(),
)
assert result.modified is True
assert result.tokens_saved == 3
assert result.compressed == "alpha beta"
assert "router:openai:responses:message:kompress" in result.transforms_applied
def test_compression_unit_keeps_lossy_unmarked_tool_output_verbatim():
original = (
"src/app.py:12 render shell status panel\n"
"src/ui.py:44 draw health badge\n"
"src/theme.py:9 set accent color"
)
result = compress_unit_with_router(
CompressionUnit(
text=original,
provider="openai",
endpoint="responses",
role="tool",
item_type="local_shell_call_output",
min_bytes=1,
),
router=Router("shell output looks organized and green"),
tokenizer=TokenCounter(),
)
assert result.modified is False
assert result.reason == "lossy_unrecoverable_tool_output"
assert result.original == original
assert result.compressed == original
def test_compression_unit_accepts_lossy_tool_output_when_recoverable():
original = "alpha beta gamma delta epsilon zeta eta theta"
result = compress_unit_with_router(
CompressionUnit(
text=original,
provider="openai",
endpoint="responses",
role="tool",
item_type="local_shell_call_output",
min_bytes=1,
),
router=Router("summary <<ccr:abc123>>"),
tokenizer=TokenCounter(),
)
assert result.modified is True
assert result.reason is None
assert result.compressed == "summary <<ccr:abc123>>"
def test_compression_unit_still_compresses_non_shell_tool_output():
result = compress_unit_with_router(
CompressionUnit(
text="alpha beta gamma delta epsilon zeta eta theta",
provider="openai",
endpoint="responses",
role="tool",
item_type="function_call_output",
min_bytes=1,
),
router=Router("summary for tool=0"),
tokenizer=TokenCounter(),
)
assert result.modified is True
assert result.reason is None
assert result.compressed == "summary for tool=0"
def test_compression_unit_still_compresses_assistant_text():
result = compress_unit_with_router(
CompressionUnit(
text="alpha beta gamma delta epsilon",
provider="openai",
endpoint="responses",
role="assistant",
item_type="message",
min_bytes=1,
metadata={"compress_assistant": "true"},
),
router=Router("alpha beta"),
tokenizer=TokenCounter(),
)
assert result.modified is True
assert result.reason is None
assert result.compressed == "alpha beta"
def test_compression_unit_rejects_non_shrinking_replacement():
result = compress_unit_with_router(
CompressionUnit(
text="alpha beta",
provider="anthropic",
endpoint="messages",
role="tool",
item_type="tool_result",
min_bytes=1,
),
router=Router("alpha beta gamma"),
tokenizer=TokenCounter(),
)
assert result.modified is False
assert result.reason == "rejected_not_smaller"
assert result.original == "alpha beta"
def test_compression_unit_respects_cache_zone_and_floor():
frozen = compress_unit_with_router(
CompressionUnit(
text="alpha beta gamma delta",
provider="anthropic",
endpoint="messages",
role="tool",
item_type="tool_result",
cache_zone="frozen",
min_bytes=1,
),
router=Router("alpha"),
tokenizer=TokenCounter(),
)
small = compress_unit_with_router(
CompressionUnit(
text="small text",
provider="openai",
endpoint="responses",
role="tool",
item_type="function_call_output",
min_bytes=500,
),
router=Router("small"),
tokenizer=TokenCounter(),
)
assert frozen.modified is False
assert frozen.reason == "cache_zone_frozen"
assert small.modified is False
assert small.reason == "below_unit_floor"
def test_batch_compression_preserves_provider_slot_references():
routed = [
RoutedCompressionUnit(
unit=CompressionUnit(
text="alpha beta gamma",
provider="openai",
endpoint="responses",
role="assistant",
item_type="message",
metadata={"compress_assistant": "true"},
min_bytes=1,
),
slot=("input", 3, "output"),
),
RoutedCompressionUnit(
unit=CompressionUnit(
text="one two three",
provider="gemini",
endpoint="generateContent",
role="user",
item_type="part.text",
min_bytes=1,
),
slot={"path": ["contents", 0, "parts", 0, "text"]},
),
]
results = compress_units_with_router(
routed,
router=Router("short"),
tokenizer=TokenCounter(),
)
assert results[0][0] == ("input", 3, "output")
assert results[1][0] == {"path": ["contents", 0, "parts", 0, "text"]}
assert [result.modified for _slot, result in results] == [True, False]
def test_compress_unit_protects_prompt_roles() -> None:
for role, reason in [
("user", "protected_user_message"),
("developer", "protected_system_message"),
("system", "protected_system_message"),
("assistant", "protected_assistant_message"),
]:
unit = CompressionUnit(
text="alpha beta gamma delta",
provider="openai",
endpoint="responses",
role=role,
item_type="message",
min_bytes=1,
)
result = compress_unit_with_router(unit, router=Router("alpha"), tokenizer=TokenCounter())
assert result.modified is False
assert result.reason == reason
def test_live_unit_with_retrieval_marker_compresses_surrounding_text() -> None:
marker = "[100 items compressed to 10. Retrieve more: hash=abc123]"
text = f"alpha beta gamma delta epsilon\n{marker}\nzeta eta theta iota kappa"
result = compress_unit_with_router(
CompressionUnit(
text=text,
provider="openai",
endpoint="responses",
role="tool",
item_type="function_call_output",
min_bytes=1,
),
router=Router("short"),
tokenizer=TokenCounter(),
)
assert result.modified is True
assert result.reason is None
assert result.strategy == "ccr_marker_preserving"
assert result.compressed == f"short\n{marker}\nshort"
assert marker in result.compressed
assert result.tokens_saved > 0
assert "ccr_marker_preserving" in result.transforms_applied
def test_non_live_unit_with_retrieval_marker_preserves_prefix_cache() -> None:
marker = "[100 items compressed to 10. Retrieve more: hash=abc123]"
text = f"alpha beta gamma delta epsilon\n{marker}\nzeta eta theta"
result = compress_unit_with_router(
CompressionUnit(
text=text,
provider="openai",
endpoint="responses",
role="tool",
item_type="function_call_output",
cache_zone="prefix",
min_bytes=1,
),
router=Router("short"),
tokenizer=TokenCounter(),
)
assert result.modified is False
assert result.reason == "cache_zone_prefix"
assert result.compressed == text