headroom/tests/test_probe_recorder.py
Focused Instability c2106cbdab
feat: probe-based retention scoring of recorded compression events (#862)
Closes #861

## What

First piece of compression quality measurement on **real proxied
sessions** (vs the existing public-benchmark evals): an opt-in recorder
captures (original, compressed) message pairs at each compression event,
and a deterministic offline prober scores what survived.

**Recorder** (`headroom/proxy/probe_recorder.py`)
- `CompressionEventRecorder` implements the existing `PipelineExtension`
protocol, subscribed to `INPUT_COMPRESSED`. Registered ONLY when
`HEADROOM_PROBE_RECORD_DIR` is set — off means not even constructed,
zero request-path overhead.
- One JSONL line per compression event that changed tokens: `{ts,
request_id, provider, model, tokens_before, tokens_after,
transforms_applied, original_messages, compressed_messages}`. One file
per PID (no interleaving), directory mode 0700.
- Fail-open everywhere: construction failure logs a warning and disables
recording; runtime exceptions are already swallowed by
`PipelineExtensionManager.emit`.
- Enabling handler change: the two `INPUT_COMPRESSED` emit sites
(anthropic + openai) add a read-only `original_messages` reference to
event metadata. No copies, no behavior change for other consumers.

**Probes** (`headroom/evals/session_probes.py` + `headroom evals probes`
CLI)
- Probe targets extracted from ORIGINAL tool-result content across three
dimensions: **exact numerics** (number + key context, incl. JSON-quoted
keys), **artifact trail** (paths, URLs, hex hashes, UUIDs), **error
evidence** (lines matching the existing `is_error_content` heuristic).
- Each target classified as **retained** (verbatim, or surviving a
legitimate format conversion — punctuation-normalized match; numerics
require key AND value to survive; error lines tolerate dropped JSON key
prefixes), **recoverable** (absent but a CCR retrieval marker is
present), or **lost** (gone with no retrieval path).
- Report: aggregate retention per dimension, bucketed by compression
ratio (the quality-per-ratio curve), and grouped per transform.
`--json-output` for machine-readable results.
- Fully offline: no LLM, no API key. The recording format is designed to
feed an LLM-judge pass later (out of scope per #861).

## Tests

33 new tests (red before, green after): `tests/test_probe_recorder.py`
(11 — event filtering, JSONL shape, env activation, fail-open on
unusable path, 0700 dir mode) and `tests/test_session_probes.py` (22 —
extraction per dimension incl. JSON-quoted numerics,
retained/recoverable/lost classification, format-change survival for
numerics and error lines, ratio bucketing, transform dedup,
malformed-line skipping, report rendering/serialization). Both proxy
lifecycle tests additionally assert the INPUT_COMPRESSED
`original_messages` metadata contract end-to-end through the real
anthropic/openai handlers, so a refactor cannot silently disable the
recorder.

Local runs: new tests + `tests/test_proxy_pipeline_lifecycle.py` +
`tests/test_canonical_pipeline.py` + `tests/test_pipeline.py` — 45
passed. `ruff check` + `uvx ruff format --check` clean.

### Self-review hardening (second commit)

- Hex artifact regex now requires at least one `a-f`, so bare decimal
runs (timestamps, counters) no longer inflate the artifact dimension.
- Inflation events (ratio > 1, the #847 territory) get an explicit
`1.00+ (inflated)` ratio bucket instead of silently dropping out of the
bucketed view.
- `run_probes` streams recording files line by line instead of slurping
them.
- Documented honestly: marker recoverability is event-scoped
(comparative metric, not absolute); recorder writes synchronously on the
request path (diagnostic sessions, not always-on).
- `headroom/evals/README.md` gained a Session Probes usage section.

## Real behavior proof

**Setup:** macOS (Darwin 25.5), Python 3.11.9, this branch, real proxy
(`python -m headroom.proxy.server --port 18994 --anthropic-api-url
http://127.0.0.1:18995`) with a local mock Anthropic upstream (no key),
`HEADROOM_PROBE_RECORD_DIR=/tmp/headroom-probe-proof/recordings`.

**Steps:** POSTed three Anthropic-format conversations whose tool
results carry large JSON arrays (220-row uniform logs, 3000-row logs,
800 heterogeneous events), each containing known numerics, paths, trace
hashes, and one error line.

**Observed** — recorder wrote `compression-events-<pid>.jsonl` (one line
per event); `headroom evals probes --recordings ...`:

```
Probed 3 compression events

Aggregate retention:
  numerics    97.7% retained,   2.3% recoverable,   0.0% lost (527 targets)
  artifacts  100.0% retained,   0.0% recoverable,   0.0% lost (6555 targets)
  errors     100.0% retained,   0.0% recoverable,   0.0% lost (3 targets)

By compression ratio (tokens_after / tokens_before):
  ratio 0.50-0.75:  numerics 100.0% retained  (CSV compaction — lossless, correctly recognized)
  ratio 0.75-1.00:  numerics  95.7% retained, 4.3% recoverable  (SmartCrusher sampling — dropped values carried a CCR marker)
```

All three classifications exercised: verbatim/format-change retention on
the CSV-compacted events, **recoverable** on the heterogeneous event
where SmartCrusher sampled rows out behind a `Retrieve more: hash=`
marker, and the injected error lines retained in every event (the
error-protection gate held). The `lost` path is covered by unit tests.
The first iteration of this proof exposed two real bugs — naive verbatim
matching misreported lossless JSON→CSV compaction as 100% lost, and
duplicated transform markers double-counted tallies — both fixed with
regression tests.

**Not tested live:** Gemini path (no `INPUT_COMPRESSED` emit parity —
pre-existing, same gap as #819); LLM-judge scoring (out of scope per
#861).

## Security

Recordings contain full conversation content in plaintext: opt-in env
var only, local disk only, dir mode 0700, documented in CLI help.

## Out of scope (per #861)

LLM-judge dimensions (decisions/intent, next steps), ACON-style
counterfactual replay, automatic rule revision.

---------

Co-authored-by: Ash Rhodes <ashley.rhodes@king.com>
2026-06-11 13:02:36 -05:00

139 lines
4.2 KiB
Python

"""Tests for the opt-in compression event probe recorder."""
import json
import stat
from headroom.pipeline import PipelineEvent, PipelineStage
from headroom.proxy.probe_recorder import (
RECORD_DIR_ENV,
CompressionEventRecorder,
probe_recorder_from_env,
)
ORIGINAL = [
{
"role": "user",
"content": [{"type": "tool_result", "tool_use_id": "t1", "content": "retry_limit: 3"}],
}
]
COMPRESSED = [
{
"role": "user",
"content": [{"type": "tool_result", "tool_use_id": "t1", "content": "[compressed]"}],
}
]
def _metadata(**overrides):
metadata = {
"tokens_before": 100,
"tokens_after": 40,
"transforms_applied": ["smart_crusher"],
"original_messages": ORIGINAL,
}
metadata.update(overrides)
return metadata
def _event(stage=PipelineStage.INPUT_COMPRESSED, messages=COMPRESSED, metadata=None):
return PipelineEvent(
stage=stage,
operation="proxy.request",
request_id="req-1",
provider="anthropic",
model="claude-test",
messages=messages,
metadata=_metadata() if metadata is None else metadata,
)
class TestCompressionEventRecorder:
def test_records_compression_event(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event())
lines = recorder.path.read_text(encoding="utf-8").splitlines()
assert len(lines) == 1
record = json.loads(lines[0])
assert record["request_id"] == "req-1"
assert record["provider"] == "anthropic"
assert record["model"] == "claude-test"
assert record["tokens_before"] == 100
assert record["tokens_after"] == 40
assert record["transforms_applied"] == ["smart_crusher"]
assert record["original_messages"] == ORIGINAL
assert record["compressed_messages"] == COMPRESSED
assert record["ts"] > 0
def test_appends_one_line_per_event(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event())
recorder.on_pipeline_event(_event())
assert len(recorder.path.read_text(encoding="utf-8").splitlines()) == 2
def test_ignores_other_stages(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event(stage=PipelineStage.INPUT_ROUTED))
assert not recorder.path.exists()
def test_skips_without_original_messages(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event(metadata=_metadata(original_messages=None)))
assert not recorder.path.exists()
def test_skips_zero_token_delta(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event(metadata=_metadata(tokens_after=100)))
assert not recorder.path.exists()
def test_skips_without_compressed_messages(self, tmp_path):
recorder = CompressionEventRecorder(tmp_path)
recorder.on_pipeline_event(_event(messages=None))
assert not recorder.path.exists()
def test_record_dir_is_private(self, tmp_path):
record_dir = tmp_path / "recordings"
CompressionEventRecorder(record_dir)
mode = stat.S_IMODE(record_dir.stat().st_mode)
assert mode == 0o700
class TestProbeRecorderFromEnv:
def test_disabled_without_env(self, monkeypatch):
monkeypatch.delenv(RECORD_DIR_ENV, raising=False)
assert probe_recorder_from_env() is None
def test_disabled_with_blank_env(self, monkeypatch):
monkeypatch.setenv(RECORD_DIR_ENV, " ")
assert probe_recorder_from_env() is None
def test_enabled_with_env(self, tmp_path, monkeypatch):
record_dir = tmp_path / "recordings"
monkeypatch.setenv(RECORD_DIR_ENV, str(record_dir))
recorder = probe_recorder_from_env()
assert isinstance(recorder, CompressionEventRecorder)
assert record_dir.is_dir()
def test_fail_open_on_unusable_path(self, tmp_path, monkeypatch):
blocker = tmp_path / "not-a-dir"
blocker.write_text("file", encoding="utf-8")
monkeypatch.setenv(RECORD_DIR_ENV, str(blocker / "recordings"))
assert probe_recorder_from_env() is None