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Author SHA1 Message Date
Tejas Chopra
f9807fd69e
feat(proxy): let extensions report cost savings and their own latency (#3051)
## What

Two changes that let a proxy extension report **what it saved** and
**what it cost**, so both show up under `/stats`, the dashboard, and
Prometheus.

`record_scope_savings` already existed and already accepted `usd` — the
one channel in the proxy that can express savings *without* tokens. Two
things stopped it working end to end.

### 1. Savings were silently dropped on Gemini traffic (bug)

`bind_scope` shares one attribution ledger between ASGI middleware and
the request handler. Anthropic and OpenAI call it; **Gemini never did**,
so anything an extension recorded into the request scope was discarded
for Gemini traffic only — silently, because an empty ledger and an
unbound one are indistinguishable at the outcome funnel. Now bound at
all four Gemini tag sites.

### 2. An extension's own latency was invisible (gap)

`overhead_ms` is measured *inside* the handler, and an ASGI extension
**wraps** that handler — so every millisecond it spends reaches the
client while every timing surface stays flat. An extension that halves
the bill and adds 200 ms per request is a trade the operator has to see
both halves of, and only one half was reaching the dashboard.

`record_scope_timing(scope, stage, ms)` is the symmetric counterpart to
`record_scope_savings`, carried on the same bound ledger and merged into
`RequestOutcome.pipeline_timing` at the outcome funnel — one place, so
every provider picks it up at once.

## API surface

```python
from headroom.proxy.savings_attribution import record_scope_savings, record_scope_timing

record_scope_savings(scope, "my_extension", tokens=0, usd=0.004)   # money without tokens
record_scope_timing(scope, "my_extension", elapsed_ms)
```

Both take the ASGI `scope`, because middleware has no other way in.
Documented in `extensions.py` — the module extension authors actually
read, and the stability contract for this interface.

- Savings → `/stats` `savings.by_source`, dashboard card,
`headroom_savings_attributed_usd_total{source=...}`
- Timing → `/stats` `pipeline_timing`, dashboard Performance panel,
`headroom_transform_timing_ms_*`

**Attribution only.** These rows explain the headline total; they are
never added to it.

## Changes to existing behavior

- `public_tags` now strips `_headroom_stage_timing` as well as
`_headroom_savings_attribution`. Both ride on `tags` because that is the
one dict reaching the outcome funnel from every handler, and a list and
a dict must not land in a string-keyed label store.
- `pipeline_timing` passed to `metrics.record_request` is merged rather
than passed through **only when an extension contributed timings**; with
no extension the handler's own dict is passed through unchanged
(asserted by identity in the tests).
- Stage names are extension-supplied, so they are capped at 16 and
namespaced `ext:` — `deep_copy` reported by a plugin must never
accumulate into the same series as `deep_copy` measured by the pipeline.
A handler's own timing wins a collision (unreachable while the prefix
stands; the safe way round if it ever goes).

## Failure modes

Both calls are bounded (32 sources, 16 stages), never raise, and never
change a response — telemetry from a plugin must not be able to break
the request it is describing. Non-positive and non-numeric durations are
ignored: a zero is a clock artifact, not an observation, and averaging
it in would drag the mean down exactly where the stage is cheapest to
skip. `timings_from_tags` tolerates junk on the tag.

## Test-double fix

Three Gemini test fakes (`FakeRequest`, `_FakeRequest`,
`_VertexGeminiImageRequest`) had no `.scope`, which every real Starlette
`Request` has. They now do. This is a double that had drifted from the
type it stands in for; the alternative was weakening the handler to
tolerate a request shape that cannot occur in production.

---

## Real behavior proof

**Setup:** macOS 15.4 (darwin 25.4.0), Python 3.12.13, this branch at
`c814b950`, real `create_app` proxy with `respx`-mocked Anthropic
upstream, a demo ASGI extension added via `app.add_middleware`.

**The extension** — written as a third party would, reporting `tokens=0`
because it re-routed `claude-opus-5` → `claude-haiku-4-5`: same tokens,
cheaper model. That is precisely the case no existing Headroom savings
channel can express, since all of them compute `saved = before - after`.

```python
class DemoRouter:
    def __init__(self, app): self.app = app
    async def __call__(self, scope, receive, send):
        if scope.get("type") != "http":
            return await self.app(scope, receive, send)
        started = time.perf_counter()
        record_scope_savings(scope, "routemegood", tokens=0, usd=0.173)
        record_scope_timing(scope, "routemegood", (time.perf_counter() - started) * 1000)
        await self.app(scope, receive, send)
```

**Ran:** three POSTs to `/v1/messages`, then `GET /stats` and `GET
/metrics`.

**Observed:**

```
upstream call -> 200
upstream call -> 200
upstream call -> 200

=== /stats  savings.by_source  (what the dashboard renders) ===
[
  {
    "source": "routemegood",
    "realized": true,
    "events": 3,
    "tokens": 0,
    "usd": 0.519
  }
]

=== /stats  pipeline_timing  (dashboard Performance panel) ===
{
  "ext:routemegood": {
    "average_ms": 0.01,
    "max_ms": 0.02,
    "count": 3
  }
}

=== /metrics ===
# HELP headroom_savings_attributed_tokens_total Tokens attributed to a savings source
# TYPE headroom_savings_attributed_tokens_total counter
headroom_savings_attributed_tokens_total{realized="true",source="routemegood"} 0
# HELP headroom_savings_attributed_usd_total Cost savings attributed to a source; may be negative
# TYPE headroom_savings_attributed_usd_total gauge
headroom_savings_attributed_usd_total{realized="true",source="routemegood"} 0.519
headroom_transform_timing_ms_sum{transform="ext:routemegood"} 0.03
```

`$0.519 = 3 × $0.173` — three requests, correctly accumulated, with
`tokens: 0` throughout.

**Also have (not a substitute for the above):** 22 new unit tests in
`tests/test_extension_attribution.py`, including four that drive the
real `_record_request_outcome` funnel via the same descriptor-binding
harness `test_request_outcome.py` uses.

Full suite on this branch: **10,989 passed, 578 skipped**. Three
failures —
`test_graceful_shutdown.py::test_run_server_installs_cancelled_error_filter`
(full-suite ordering; passes in isolation),
`test_learn/test_integration.py::TestCodexIntegration::test_full_pipeline`,
and `test_release_workflows.py::test_no_native_tls_in_wheel_build_tree`
(needs `cargo`) — **reproduce identically on clean `main`** (`2f4d001c`,
10,967 passed, same 3 failed). Verified by stashing this branch and
re-running the full suite on main in the same tree.

**What I did not test:** a live provider (upstream is `respx`-mocked);
the Gemini `bind_scope` fix against real Google traffic (covered by the
existing 114 Gemini tests, which all pass); the dashboard rendered in a
browser — I verified the JSON shape its templates bind to
(`stats.savings?.by_source`, `stats.pipeline_timing`) rather than the
pixels.

---

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

---------

Co-authored-by: Tejas Chopra <tejas@Tejass-MacBook-Pro.local>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
2026-08-16 10:25:47 -07:00
inix
806d2e468a
fix(proxy): offload OpenAI and Gemini tokenizer counting off the event loop (#2498)
## Description

The OpenAI and Gemini handlers resolved the tokenizer and counted the
conversation inline on the event loop. When a model resolves to a
HuggingFace tokenizer (the registry routes qwen, deepseek, llama, phi,
falcon, and more there) a cold cache runs
`AutoTokenizer.from_pretrained` behind a 10s `thread.join`, which
freezes the whole server. That is the GH #1701 stall, now reachable from
OpenAI and Gemini because `/v1/chat/completions` and `/v1/responses` are
documented multi-provider passthroughs and receive those models.

Anthropic already routed the same call through a fail-open
`_count_tokens_offloaded` helper. This hoists that helper to the shared
`HeadroomProxy` base and sends the OpenAI and Gemini sites through it
too.

No linked issue. This is the OpenAI and Gemini follow-on to #1738, which
offloaded the Anthropic and batch paths. GH #1701 is the original freeze
report.

## 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

- Hoisted `_count_tokens_offloaded` from `AnthropicHandlerMixin` to the
shared `HeadroomProxy` base, next to `_run_compression_in_executor`. It
resolves and counts on the bounded compression executor and fails open
to estimation on timeout, error, or executor quarantine.
- Routed 6 inline sites through it: `handle_openai_chat`,
`handle_openai_responses`, `handle_gemini_generate_content`,
`handle_google_cloudcode_stream`, `handle_gemini_count_tokens`, and
`handle_gemini_stream_generate_content` (resolve only, keeps its
per-part `count_text` loop).
- Removed 6 now-dead local `get_tokenizer` imports.
- Left batch's per-line counts inline on purpose. They run on an
already-warm tokenizer, so offloading them adds executor churn without
touching the cold load. Batch's `pipeline.apply` was already offloaded
in #1738.
- Extended the wiring guard to all 7 provider handlers, added a
quarantine fail-open test and a `count_text` fail-open test, and stubbed
the method on 2 mixin-only handler doubles.

## Testing

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

### Test Output

```text
$ ruff check headroom/proxy/server.py headroom/proxy/handlers/{anthropic,openai,gemini}.py tests/test_tokenizer_count_offload.py
All checks passed!

$ pytest tests/test_tokenizer_count_offload.py
6 passed in 4.39s

# offload suite + all 26 handler-calling test files + handler-helpers/batch/tokenizers
$ pytest tests/test_tokenizer_count_offload.py tests/test_openai_codex_routing.py tests/test_gemini_nonjson_status.py ... tests/test_tokenizers.py
377 passed, 15 skipped, 15 warnings in 86.60s (0:01:26)
```

## Real Behavior Proof

- Environment: macOS (Darwin), Python 3.13, proxy built from this
branch. A synthetic tokenizer that sleeps 0.5s on resolve+count stands
in for a cold HuggingFace `from_pretrained` load, with a 10ms asyncio
loop-canary running alongside.
- Exact command / steps: monkeypatch `headroom.tokenizers.get_tokenizer`
to the 0.5s-sleeping tokenizer, then time a concurrent canary across two
counts, the offloaded `await
proxy._count_tokens_offloaded("qwen2.5-coder", messages)` and the old
inline `get_tokenizer(model).count_messages(messages)`.
- Observed result: the offloaded path kept the loop live at 41 canary
ticks during the 509ms count, the inline path froze it to 0 ticks over
502ms, and both returned the same token count. Full run was 377 passed,
15 skipped, 0 failed. The new quarantine test confirms an unrelated
compression timeout downgrades counting to estimation instead of raising
a 500.
- Not tested: live HuggingFace downloads and real qwen/deepseek traffic.
No API keys in this environment, so the Gemini and OpenAI integration
tests skip on `GEMINI_API_KEY`/`OPENAI_API_KEY`. `mypy headroom` did not
finish locally (cold-times-out past 10 minutes on this box), so
type-checking is left to CI.

## 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 or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] I did **not** edit `CHANGELOG.md` — it is generated by
release-please from my Conventional Commit PR title (a CI guard enforces
this)

## Additional Notes

- No linked issue. Follow-on to #1738.
- Batch per-line counts stay inline: they run on an already-warm
tokenizer, so offloading them adds executor churn without addressing the
cold load.
- Found a 6th site mid-implementation.
`handle_gemini_stream_generate_content` also resolved the tokenizer
inline but counts via a `count_text` loop, so it takes the resolve-only
path. Verified `EstimatingTokenCounter.count_text` exists, so its
fail-open branch does not crash.
- `mypy headroom` cold-times-out locally (server.py pulls the full
graph). Deferred to CI's Linux shards, same as prior PRs on this file.
`ruff` and `pytest` run clean.
- Documentation checkbox left unchecked: this change ships no
user-facing doc update.

---------

Co-authored-by: JerrettDavis <mxjerrett@gmail.com>
2026-07-22 21:01:05 -07:00
Abhay Singh
f723925be7
fix(proxy/gemini): forward a non-JSON upstream body with its real status (#2174)
## Description

`handle_gemini_generate_content` turns a non-JSON upstream error
response into a generic 502, hiding the real status and body.

After the upstream call it extracts usage from `response.json()`:

```python
try:
    resp_json = response.json()
    usage = resp_json.get("usageMetadata", {})
    ...
    cache_read_tokens = usage.get("cachedContentTokenCount", 0)
except (KeyError, TypeError, AttributeError) as e:      # <-- missing JSONDecodeError / ValueError
    ...
```

`response.json()` raises `json.JSONDecodeError` (a `ValueError`
subclass) for a non-JSON body. That isn't in the tuple, so it escapes to
the function's outer `except Exception`, which returns a synthetic 502
and discards the real `response.status_code` / `response.content` (which
the success path forwards verbatim). An overloaded Google/Vertex/Copilot
frontend commonly returns a 503/500/429 with an HTML or empty body, so
the client sees a generic 502 instead of the true status — defeating
retry/backoff and dropping the diagnostic.

The all-non-text early-exit branch in the same handler already handles
this correctly with the full tuple (`except (json.JSONDecodeError,
ValueError, KeyError, TypeError, AttributeError)`) and then forwards the
real status/content.

## Fix

Add `json.JSONDecodeError, ValueError` to the token-extraction `except`,
matching that sibling. On a non-JSON body the extraction is skipped
(token metrics keep their fallbacks) and the handler falls through to
`return Response(content=response.content,
status_code=response.status_code, ...)` — the real status and body.

Closes #

## 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

- `headroom/proxy/handlers/gemini.py`: broaden the token-extraction
`except` in `handle_gemini_generate_content` to include
`json.JSONDecodeError, ValueError`.
- `tests/test_gemini_nonjson_status.py`: new test asserting that except
clause catches the JSON/ValueError family (guards against the
regression).
- `CHANGELOG.md`: Bug Fixes entry.

## Testing

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

### Test Output

```text
$ uvx ruff@0.15.17 check headroom/proxy/handlers/gemini.py tests/test_gemini_nonjson_status.py
All checks passed!
$ python -m py_compile headroom/proxy/handlers/gemini.py tests/test_gemini_nonjson_status.py
OK
```

## Real Behavior Proof

- Environment: Windows 11, Python 3.12, `uvx ruff@0.15.17`. A full
`pytest` OOM-kills this box (ML stack import), so I verified the
exception handling with a dependency-free script that models the
token-extraction try/except plus the handler's verbatim-forward return,
and left the full pytest to CI.
- Exact command / steps: sent a 503 response whose `.json()` raises
`JSONDecodeError` (non-JSON body) through the old tuple and the new
tuple, plus a normal JSON 200 as a control.
- Observed result: old lets `JSONDecodeError` escape (→ the outer
handler's synthetic 502); new catches it and forwards the real 503; the
JSON 200 still extracts tokens under both. The new test asserts the real
handler's except clause includes the JSON/ValueError family.
- Not tested: a live overloaded Gemini upstream; full local `pytest`
deferred to CI (OOM).

## 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 or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [x] I have updated the CHANGELOG.md if applicable

## Additional Notes

The "unit tests pass locally" / "type checking" boxes are unchecked
because the full suite imports the ML stack, which I can't run here; the
change adds two exception types matching an existing, tested sibling
branch, verified by the standalone proof and a source-level regression
guard (a full handler-integration harness for Gemini doesn't exist
in-tree, and the existing gemini integration tests hit a live API).

---------

Co-authored-by: JerrettDavis <mxjerrett@gmail.com>
Co-authored-by: Tejas Chopra <chopratejas@gmail.com>
2026-07-14 12:20:11 -04:00