headroom/CONTRIBUTING.md
Joel Belanger 0b4a4bd483
fix: support Copilot Business subscription auth (#641)
## Description

Adds a first-party `headroom copilot-auth login` flow for Copilot
subscription
mode and uses the resulting Copilot OAuth token to perform GitHub's
Copilot
token exchange before launching the wrapped Copilot CLI.

This fixes Business/Enterprise Cloud accounts where a generic
GitHub/Copilot
token can read Copilot account metadata but is rejected by the Copilot
token
exchange endpoint. It also avoids treating GitHub.com Enterprise Cloud
account
URLs such as `github.com/enterprises/acme` as API hostnames.

Fixes #635
Related: #488, #610
Builds on #576

## Type of Change

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

## Changes Made

- Adds `headroom copilot-auth login` and `headroom copilot-auth status`.
- Stores a Headroom-specific Copilot OAuth token under Headroom's state
dir.
- Exchanges reusable Copilot OAuth tokens with Copilot Chat-compatible
headers before subscription-mode launch.
- Carries the resolved Copilot API endpoint into `headroom wrap copilot
--subscription`.
- Handles GitHub.com Enterprise Cloud URLs without synthesizing invalid
`api.github.com/enterprises/...` hosts.
- Adds focused unit tests and README guidance for subscription login.

## 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

```console
ruff check headroom/copilot_auth.py headroom/cli/copilot_auth.py headroom/cli/main.py headroom/cli/__init__.py headroom/cli/wrap.py tests/test_copilot_auth.py tests/test_cli/test_copilot_auth.py tests/test_cli/test_wrap_copilot.py tests/test_copilot_subscription_smoke.py
# All checks passed!

ruff format --check headroom/copilot_auth.py headroom/cli/copilot_auth.py headroom/cli/main.py headroom/cli/__init__.py headroom/cli/wrap.py tests/test_copilot_auth.py tests/test_cli/test_copilot_auth.py tests/test_cli/test_wrap_copilot.py tests/test_copilot_subscription_smoke.py
# 9 files already formatted

python -m py_compile headroom/copilot_auth.py headroom/cli/copilot_auth.py headroom/cli/main.py headroom/cli/__init__.py headroom/cli/wrap.py tests/test_copilot_auth.py tests/test_cli/test_copilot_auth.py tests/test_cli/test_wrap_copilot.py tests/test_copilot_subscription_smoke.py

uv run --no-project --with pytest --with pytest-asyncio --with click --with rich --with opentelemetry-api --with pydantic --with tiktoken --with 'litellm==1.82.3' --with fastapi --with uvicorn --with 'httpx[http2]' --with openai --with mcp --with magika --with zstandard --with websockets --with onnxruntime --with transformers --with watchdog --with sqlite-vec pytest tests/test_copilot_auth.py tests/test_cli/test_copilot_auth.py tests/test_cli/test_wrap_copilot.py tests/test_cli_proxy_env.py tests/test_copilot_subscription_smoke.py
# 127 passed
```

Local note: `uv run pytest ...` against the project currently fails
before
running tests because `uv.lock` has an unrelated `gitpython`
wheel/version
mismatch.

## Manual Validation

I tested this with an existing GitHub Copilot Business subscription
associated with a GitHub.com Enterprise Cloud account.

The Enterprise Cloud value I tested was in the form:

```text
github.com/enterprises/<enterprise>
```

The tested flow was:

```text
headroom copilot-auth login
headroom wrap copilot --subscription -- --model gpt-5.4
```

This validated that Headroom does not treat
github.com/enterprises/<enterprise> as a Copilot API hostname. Instead,
token exchange uses GitHub.com and Headroom routes subscription-mode
traffic to the Copilot API endpoint returned by GitHub for the signed-in
account.

I did not test this with GitHub Enterprise Server or a custom enterprise
domain such as ghe.example.com.

No tokens, request IDs, or organization-specific identifiers are
included in this PR.

## Real Behavior Proof

- Environment: macOS Darwin, Python 3.12.7, local checkout on
`codex/copilot-business-auth`.
- Exact command / steps: Ran `headroom copilot-auth login`, then
launched `headroom wrap copilot --subscription -- --model gpt-5.4` with
a GitHub Copilot Business subscription tied to a GitHub.com Enterprise
Cloud account.
- Observed result: Headroom did not treat
`github.com/enterprises/<enterprise>` as a Copilot API hostname; token
exchange used GitHub.com and subscription traffic was routed to the
Copilot API endpoint returned for the signed-in account. The latest
focused Copilot auth/proxy tests pass locally (`127 passed`).
- Not tested: GitHub Enterprise Server or custom enterprise domains such
as `ghe.example.com`; Windows Credential Manager integration still needs
confirmation from someone on Windows.

## 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 targeted unit tests pass locally with my changes
- [ ] I have updated the CHANGELOG.md if applicable

## Screenshots (if applicable)

N/A

## Additional Notes

Acknowledgement: the OAuth/token-exchange behavior was informed by
`anomalyco/opencode-copilot-auth` by Aiden Cline.

No tokens are printed by the new login/status commands; only a short
SHA-256
fingerprint is displayed for troubleshooting.

The interactive login is included because the missing piece is not just
an
Enterprise URL or routing hint. For GitHub.com Enterprise Cloud
accounts,
URLs like `github.com/enterprises/acme` identify the enterprise account
but
are not Copilot API hostnames; token exchange still happens through
GitHub.com
and then returns the account-specific Copilot API endpoint. A
command-line
enterprise argument can help for true GitHub Enterprise
Server/custom-domain
deployments, but it cannot produce the Copilot OAuth token class that
the
token-exchange endpoint accepts.

Ideally, Headroom would avoid an extra interactive login and reuse an
existing
GitHub/Copilot CLI session everywhere. In practice, some
reusable-looking
tokens can read Copilot account metadata but are rejected by Copilot
token
exchange, which leaves Business/Enterprise Cloud users with missing
model
catalogs. The explicit login command is the smallest independent way to
obtain
and persist the token needed for that exchange without asking users to
pass a
secret on the command line.

---------

Co-authored-by: jbelanger <your-username@users.noreply.github.com>
2026-06-12 20:46:38 -05:00

5.6 KiB

Contributing to Headroom

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Development setup

git clone https://github.com/chopratejas/headroom.git
cd headroom
python -m venv .venv && source .venv/bin/activate
node --version  # Node 18+ required for commitlint hooks
python -m pip install --upgrade pip
python -m pip install -e ".[dev,relevance,proxy]"
python -m pytest

Headroom uses a pyproject.toml/maturin build backend. Older pip versions may fail editable installs by looking for setup.py; upgrade pip first or use uv sync --extra dev.

Dev Containers

Two configs ship for VS Code / Codespaces:

  • .devcontainer/devcontainer.json — Python 3.12, uv, Node.js, gh.
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Inside, use: uv run ruff check ., uv run pytest, etc.

Optional automated review

This repository includes .github/copilot-instructions.md so maintainers can opt into GitHub Copilot code review without adding workflow billing noise to every PR.

Enable or disable automatic Copilot review in Settings → Rules → Rulesets → Automatically request Copilot code review. Keep it off unless maintainers explicitly want the extra review traffic.

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Performance: transforms <50ms at P99, lazy-load optional deps, profile before optimizing.

Contributors are credited in CHANGELOG, the GitHub contributors page, and release notes. Thanks again. 💚