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Author SHA1 Message Date
JD Davis
3077ac81e8
feat: add deterministic runtime rollout controls (#1490)
## Description

Establish one centrally resolved, observable, deterministic, versioned
runtime rollout-control mechanism for Headroom. Runtime rollout controls
which behaviors an already-built artifact may expose; it does not select
or qualify a Headroom release/version.

## Type of Change

- [x] New feature (non-breaking change that adds functionality)
- [x] Bug fix (non-breaking change that fixes rollout enforcement
regressions)
- [x] Documentation update
- [x] Code refactoring (no functional changes)

## Changes Made

- Added `RolloutChannel`, `HEADROOM_ROLLOUT_CHANNEL`,
`--rollout-channel`, and a versioned immutable `RolloutSnapshot` shared
by Python configuration boundaries.
- Added schema/policy versions, canonical registry and snapshot SHA-256
identities, per-feature decision reasons, disable precedence, unsafe
qualification poisoning, strict CLI validation, and fail-closed
environment handling.
- Added `headroom rollout status --json`, Python `/stats.rollout`, and
Rust `/rollout/status` runtime provenance.
- Added equivalent Rust snapshot semantics and shared Python/Rust policy
vectors while retaining language-specific feature registries.
- Enforced rollout policy at alternate Python server composition roots
so `HEADROOM_READ_MATURATION=1` cannot bypass its beta gate.
- Preserved typed rollout snapshots across multi-worker serialization
with schema, policy, registry, snapshot-digest, type, and feature-name
validation.
- Made loopback runtime output-shaper updates replace the immutable
snapshot atomically for request readers, retain explicit request/disable
provenance, preserve channel and kill-switch precedence, invalidate
cached stats, and return the effective rollout decision.
- Made `headroom learn --verbosity --apply` report a channel-blocked
update instead of claiming the shaper is live.
- Made explicit CLI feature flags fail loudly when their current channel
blocks them.
- Made persistent interceptor installation select canary automatically,
or reject an explicitly insufficient channel unless the break-glass
override is set.
- Updated architecture, proxy, rollout, learn, and output-shaper
documentation with required channels and hot-reload semantics.

## Testing

- [x] Unit tests pass
- [x] Linting passes (`ruff check .` and `ruff format --check .`)
- [x] Type checking passes (`mypy headroom --ignore-missing-imports`)
- [x] New regression tests added for every corrected behavior
- [x] Rust tests and production-target Clippy pass
- [x] Documentation build passes

### Test Output

```text
Focused rollout coverage suite
57 passed; headroom.rollout + rollout CLI: 98% coverage

Affected proxy/rollout/transform/governance suites
222 passed; 0 failed

Final changed regression suites
100 passed; 0 failed

Cross-module hot-reload isolation regression
6 passed; 0 failed

cargo test -p headroom-core -p headroom-proxy --quiet
headroom-core: 924 passed; 1 ignored
headroom-proxy and integration suites: all passed

cargo clippy -p headroom-core -p headroom-proxy --lib --bins -- -D warnings
cargo fmt --all -- --check
ruff check .
ruff format --check .
mypy headroom --ignore-missing-imports
git diff --check
All passed

cd docs && npm run build
Compiled successfully; 164 static pages generated
```

The unsharded Windows-only CI selection exposed unrelated baseline
failures, principally the existing `sqlite:///C:\\...` URL parser
producing an invalid `\\C:\\...` path. At commit `8e793a80`, all 52
completed GitHub checks passed; the only other conclusions are expected
skips and superseded governance jobs.

## Real Behavior Proof

- **Environment:** Windows checkout on Python 3.13.3 and the current
Rust workspace, based on upstream `main` at `93f2d7a2`.
- **Exact command / steps:** Exercised canary and beta feature requests
through CLI status, Python `/stats.rollout`, Rust `/rollout/status`,
multi-worker payload round trips, loopback `/admin/runtime-env`, real
proxy request shaping before/after hot reload, installer manifest
generation, and shared Python/Rust policy vectors.
- **Observed result:** Stable blocks unstable requests; disable wins
over explicit/default/legacy/unsafe paths; unsafe state reports
`qualification_eligible=false`; worker handoff rejects tampering;
running output shaping changes only when the effective beta policy
permits it; explicit blocked flags fail with actionable diagnostics.
- **Not tested:** Live production traffic requiring provider
credentials, or future artifact qualification/promotion automation
(intentionally out of scope).

## Runtime Rollout Safety

- **Rollout-managed features:** Python `tool_result_interceptors`,
`proxy_output_shaper`, `read_maturation`; Rust `native_bedrock`,
`openai_responses_streaming`, `canary_probe`.
- **Minimum rollout channel:** Registry-defined per feature; process
default is `stable`.
- **Stable/default behavior changed:** No unstable feature becomes
enabled by default. Explicit blocked CLI flags now fail instead of
silently doing nothing.
- **Kill switch / disable path:**
`HEADROOM_DISABLE_FEATURES=<comma-separated feature names>`; explicit
disable has highest precedence, including over the unsafe override.
- **Unsafe override required:** No.
`HEADROOM_UNSAFE_ALLOW_UNSTABLE_FEATURES=1` is break-glass only and
makes qualification evidence ineligible.
- **Qualification impact:** Adds machine-readable policy/snapshot
identities and eligibility; does not implement qualification itself.
- **Rollback path:** Set the named disable list for operational
rollback, lower the channel, or revert this PR.

## Review Readiness

- [x] I have performed a full diff 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 hard-to-understand areas
- [x] I have made corresponding documentation changes
- [x] My changes generate no new warnings
- [x] I added tests that reproduce and prevent every regression fixed
during review
- [x] New and existing affected tests pass locally
- [x] I did **not** edit `CHANGELOG.md`; release-please generates it
from the Conventional Commit PR title

## Additional Notes

Out of scope: artifact candidates, benchmark orchestration,
qualification manifests/gates, promotion automation, release branches,
publication guards, and release-risk classification. Those workflows can
consume the rollout registry digest, runtime snapshot digest, decision
reasons, and qualification eligibility through supported black-box
interfaces.

---------

Co-authored-by: JD Davis <jd@jds-macbook-air.tail2a279.ts.net>
Co-authored-by: JD Davis <jd@JDH-AIR-00.local>
2026-08-12 23:16:54 -05:00
Tejas Chopra
6904d47a01
feat(proxy): hot-reload live env knobs so a reused proxy picks them up without a restart (#1090)
## Description

A small class of env vars is read by the proxy **live, per request** —
the output-shaper family (`HEADROOM_OUTPUT_SHAPER`,
`HEADROOM_VERBOSITY_LEVEL`, `HEADROOM_EFFORT_ROUTER`,
`HEADROOM_MECHANICAL_EFFORT`, `HEADROOM_VERBOSITY_AUTOTUNE`,
`HEADROOM_OUTPUT_HOLDOUT`), or captured at import
(`HEADROOM_INTERCEPT_READ_MIN_CHARS`). The proxy reads them from its own
process environment, fixed at launch. But `headroom wrap` reuses an
already-running proxy (it restarts only on startup-config drift), so a
value exported *after* the proxy started silently no-op'd — e.g. `export
HEADROOM_OUTPUT_SHAPER=1` had zero effect on a reused proxy on `:8787`.

This PR makes those live knobs **hot-reloadable**: `headroom wrap`
pushes them to the running proxy, which applies them in memory — no
restart (a restart would cold-start the ML stack, drop in-flight
requests, and lose CCR/router caches).

_No linked issue._

## Type of Change

- [x] 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)
- [x] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)

## Changes Made

- `headroom/proxy/runtime_env.py` (new): single source of truth
registering the live knobs + a thread-safe process-global override
store. `getenv()` (override-then-env) is a drop-in for `os.environ.get`;
behaviour is byte-identical when no override is set.
- Readers rerouted through `runtime_env.getenv`: `output_shaper.py`, the
anthropic holdout read, and the ast-grep threshold (now a live read, not
an import-time constant).
- Proxy: loopback-only `POST /admin/runtime-env` applies overrides in
memory; `/health` → `config.runtime_env` surfaces the live values so
reuse is observable.
- `wrap`: after attaching to a proxy (all call sites), best-effort push
of the session's **explicitly-set** knobs. No-ops if nothing is set,
`--no-proxy`, the proxy is unreachable, or it predates the endpoint
(404). Only explicitly-set knobs are pushed, so a session never clobbers
another with a default it never asked for.
- Docs: README + output-token-reduction guide document the
global-override caveat.

## Testing

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

### Test Output

```text
$ python -m pytest tests/test_runtime_env.py -q
16 passed

$ python -m pytest tests/test_runtime_env.py tests/test_output_shaper.py -q
50 passed

$ ruff check headroom/proxy/runtime_env.py headroom/proxy/output_shaper.py headroom/proxy/handlers/anthropic.py headroom/proxy/interceptors/astgrep.py headroom/proxy/server.py headroom/cli/wrap.py
All checks passed!

$ mypy headroom/proxy/runtime_env.py
Success: no issues found in 1 source file
```

## Real Behavior Proof

- Environment: local macOS, Python 3.12 `.venv`, branch
`fix/runtime-env-hot-reload` at the PR head.
- Exact command / steps: ran the test suites above. The 16 new
`test_runtime_env` tests exercise the registry/store, overrides reaching
the shaper + the ast-grep threshold, the `POST /admin/runtime-env` apply
+ `/health` reflect + loopback-only 404 + 400-on-non-object, and the
wrap push payload / no-op / error-swallow paths.
- Observed result: 50 passed; ruff + mypy clean on the changed modules;
an override set via the endpoint is read by `getenv()` at the shaper and
surfaced in `/health` config.
- Not tested: a literal two-terminal manual session (start a proxy,
`headroom wrap` a second session, `export HEADROOM_OUTPUT_SHAPER=1`,
confirm the reused proxy picks it up). The behaviour is covered by the
endpoint + wrap-push integration tests, but was not exercised by hand
here.

## 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
- [x] 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

- **Inherent caveat (documented):** overrides are global to the proxy —
one process serves every attached wrapper, so the last explicit setting
wins. No mechanism (restart or hot-reload) can give two sessions on one
shared proxy different output-shaper settings.
- **Scope:** startup-captured settings (`HEADROOM_TARGET_RATIO` etc.)
are intentionally out of scope — a fresh proxy already gets them and
they ride the existing `/health` config channel.
- **Merge blocker:** this branch is currently **CONFLICTING with
`main`** and needs a rebase/merge before it can land.
- CHANGELOG.md left unchanged — releases are managed by release-please
from conventional commits.
2026-06-18 09:50:50 -07:00