headroom/tests/test_proxy/test_transformations_feed.py
gglucass 2269e40bde
feat(proxy): log compressed messages alongside original request (#261)
## Description

Expose the post-compression message list that was actually sent upstream
as a new `compressed_messages` field on `RequestLog`, paired with the
existing (now consistently pre-compression) `request_messages`.
Consumers of `/transformations/feed` — dashboards and any downstream
observability — can now diff the two sides of a compression to see
exactly what the pipeline stripped, replaced, or kept. Turns an abstract
"saved N tokens" into a legible before/after.

Gated by the same `log_full_messages` flag as `request_messages` so the
two sides stay in sync; it's pointless to store one without the other.

Also fixes a latent correctness bug: today's `request_messages` field is
inconsistent across the four `RequestLog` construction sites — sometimes
it's the pre-compression snapshot, sometimes it's the mutated
`body["messages"]` (which is the compressed list, because the proxy
mutates `body` in place before the log call). After this change,
`request_messages` always means pre-compression and
`compressed_messages` always means what went upstream.

## Type of Change

- [ ] Bug fix (non-breaking change that fixes an issue)
- [x] 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)

Note on "breaking": strictly speaking this is a semantic correction of
an inconsistently-populated field, not a schema break. The field name
`request_messages` is unchanged and the JSON shape is unchanged; what
changes is that the field now consistently holds the pre-compression
list. Consumers that treated it as "whatever messages we have" continue
to work. Consumers that depended on the accidental post-compression
value (if any existed) would shift to `compressed_messages`.

## Changes Made

- **`headroom/proxy/models.py`**: `RequestLog` gains
`compressed_messages: list[dict] | None = None`. Doc comment explains
it's paired with `request_messages` and gated by the same
`log_full_messages` flag.
- **`headroom/proxy/handlers/anthropic.py`** (2 sites — Bedrock
non-streaming and main non-streaming): `request_messages` now
consistently sources from `original_messages` (the pre-compression
snapshot at line 724), `compressed_messages` sources from
`body["messages"]` (the compressed list after in-place mutation at line
1189). Both gated symmetrically.
- **`headroom/proxy/handlers/streaming.py`** (2 sites — main streaming
in `_finalize_stream_response`, Bedrock streaming in
`_stream_response_bedrock`): same treatment. `_stream_response_bedrock`
gains a new `original_messages: list[dict] | None = None` parameter so
it has access to the pre-compression snapshot; the sole caller in
`anthropic.py` now threads it through.
- **`headroom/proxy/server.py`**: `/transformations/feed` adds
`compressed_messages` to the JSON payload alongside the existing
`request_messages` / `response_content`. *Split into a separate
preceding commit is a one-time EOL normalization to LF — the file blob
in history carries CRLF but `.gitattributes` declares `*.py text
eol=lf`, so any contributor editing `server.py` triggers the same
whole-file renormalization. Separating the two commits keeps this
feature commit's diff at a single line.*
- **`headroom/proxy/request_logger.py`**: `compressed_messages` is
stripped from the JSONL file log and from `get_recent()` alongside the
existing `request_messages` / `response_content` stripping.
`get_memory_stats()` also counts it toward the deque's byte budget.

## Testing

- [x] Unit tests pass (`pytest`)
- [x] Linting passes (`ruff check .` and `ruff format --check .`)
- [x] Type checking passes (`mypy headroom`)
- [x] New tests added for new functionality
- [x] Manual testing performed (via the Headroom Desktop client that
consumes `/transformations/feed` — confirmed both fields arrive and
render)

Test coverage added/extended:

- `tests/test_proxy/test_request_logger.py` (new file): round-trip unit
tests for `RequestLogger`. Confirms `get_recent` strips both sides (pre
+ post), `get_recent_with_messages` exposes both, and the JSONL file log
drops both when `log_full_messages=False`.
- `tests/test_proxy/test_transformations_feed.py`: extended to assert
`compressed_messages` appears in the endpoint payload alongside
`request_messages` / `response_content`.
- `tests/test_proxy_streaming_request_logger.py`: existing include/omit
tests updated to assert both sides populate when the flag is on and both
are `None` when it's off.

## Test Output

```
$ uv run ruff check headroom tests
All checks passed!
$ uv run ruff format --check headroom tests
614 files already formatted
$ uv run pytest tests/test_proxy/test_request_logger.py tests/test_proxy_streaming_request_logger.py tests/test_proxy/test_transformations_feed.py -v
...
tests/test_proxy/test_request_logger.py::test_get_recent_strips_compressed_messages_alongside_request_and_response PASSED
tests/test_proxy/test_request_logger.py::test_get_recent_with_messages_returns_compressed_messages PASSED
tests/test_proxy/test_request_logger.py::test_jsonl_file_strips_both_sides_when_log_full_messages_disabled PASSED
tests/test_proxy_streaming_request_logger.py::test_finalize_stream_response_logs_original_and_compressed_messages PASSED
tests/test_proxy_streaming_request_logger.py::test_finalize_stream_response_omits_messages_when_log_full_messages_disabled PASSED
tests/test_proxy/test_transformations_feed.py::test_transformations_feed_returns_messages PASSED
...
============================== 11 passed in 5.36s ==============================
```

## 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
(the two-sided gating at each log site, the `_stream_response_bedrock`
parameter addition, and the `get_memory_stats` accounting)
- [ ] 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 or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] I have updated the CHANGELOG.md if applicable

## Additional Notes

### Non-Anthropic backends

`handlers/openai.py` and `handlers/gemini.py` do not currently emit
`RequestLog` entries at all — only Anthropic and the shared streaming
paths do. This PR therefore only populates `compressed_messages` on
Anthropic traffic (which is what `/transformations/feed` shows today).
Wiring OpenAI and Gemini into `RequestLogger` end-to-end is a separate,
larger gap worth its own PR.

### `server.py` EOL normalization

The feature change in `server.py` is a single line. To keep the diff
readable, the preceding commit is a whitespace-only `chore(proxy):
normalize server.py to LF per .gitattributes` — the file blob was stored
with CRLF terminators but `.gitattributes` declares `*.py text eol=lf`.
Any contributor touching `server.py` triggers this renormalization;
isolating it here keeps the feature commit reviewable. Happy to rebase /
drop / reshape as preferred.

### Downstream desktop compatibility

The Headroom Desktop client I work on now consumes `compressed_messages`
and renders the pre/post pair side-by-side on the "Recent large
compression" card. The desktop was updated to handle both shapes:
proxies without the field render the legacy single "Request" block;
proxies with the field render "Request (original, N tokens)" + "Request
(compressed, M tokens)" where N/M come from `input_tokens_original` /
`input_tokens_optimized`. No changes needed downstream if this PR lands.

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

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-11 19:02:54 -05:00

60 lines
2.2 KiB
Python

"""Tests for the /transformations/feed endpoint in the proxy server."""
import pytest
# Skip if fastapi not available
pytest.importorskip("fastapi")
from httpx import ASGITransport, AsyncClient
from headroom.proxy.server import create_app
@pytest.fixture
def app():
return create_app()
@pytest.mark.asyncio
async def test_transformations_feed_endpoint_returns_list(app):
"""The endpoint should return a list of recent transformations."""
async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
response = await client.get("/transformations/feed")
assert response.status_code == 200
data = response.json()
assert isinstance(data, dict)
assert "transformations" in data
assert isinstance(data["transformations"], list)
@pytest.mark.asyncio
async def test_transformations_feed_returns_messages(app):
"""Each transformation exposes both the original request and the
post-compression form that was actually sent upstream, plus the response.
The pre/post pair is what makes compression legible: consumers can diff
the two to see what the pipeline stripped, replaced, or kept.
"""
async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
response = await client.get("/transformations/feed")
data = response.json()
transformations = data["transformations"]
for t in transformations:
assert "request_messages" in t
assert t["request_messages"] is None or isinstance(t["request_messages"], list)
assert "compressed_messages" in t
assert t["compressed_messages"] is None or isinstance(t["compressed_messages"], list)
assert "response_content" in t
assert t["response_content"] is None or isinstance(t["response_content"], str)
@pytest.mark.asyncio
async def test_transformations_feed_respects_limit(app):
"""The endpoint should respect a ?limit= query parameter."""
async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
response = await client.get("/transformations/feed?limit=5")
data = response.json()
assert len(data["transformations"]) <= 5