feat: add ACP terminal authentication

[TerminallyLazy]

Implementation Report — A0 ACP Registry Admission

Plan: .claude/plans/a0-acp-registry-admission.md
Branch: codex/acp-registry-admission-clean
Status: COMPLETE

Summary

A0 now conditionally advertises ACP terminal authentication and provides the
a0 acp --login command required by that method. The command reuses a verified
remembered session when available; otherwise it accepts ephemeral credentials
or prompts, and only persists the existing protected session-cookie store after
successful authentication. The package is release-ready as a0 version 2.11.0
with a GitHub Release to PyPI trusted-publishing workflow.

Tasks completed

• ACP terminal authentication → src/agent_zero_cli/acp.py (UPDATE)
• ACP login command routing → src/agent_zero_cli/__main__.py (UPDATE)
• Regression coverage → tests/test_acp.py, tests/test_entrypoint.py (UPDATE)
• Release metadata and documentation → pyproject.toml, src/agent_zero_cli/__init__.py, README.md (UPDATE)
• Trusted publishing → .github/workflows/publish-pypi.yml (CREATE)

Tests added

• Terminal authentication is only advertised to terminal-auth-capable ACP clients.
• Saved-session reuse, successful credential login, and failed login persistence behavior.
• a0 acp --login parser routing.

Validation results

• PYTHONPATH="src:$A0_SITE" /Users/lazy/a0-ready-test/.venv/bin/python -m pytest tests/test_acp.py tests/test_entrypoint.py -v — PASS, 17 tests.
• uv build --offline — PASS: built a0-2.11.0.tar.gz and a0-2.11.0-py3-none-any.whl.
• Wheel metadata inspection — PASS: Name: a0, Version: 2.11.0.
• git diff --check — PASS.

Deviations from the plan

None. The local checkout had no project virtual environment, so focused tests
used the already-installed A0 runtime packages with the existing
/Users/lazy/a0-ready-test test runner; no dependencies were installed.

Issues encountered

• The PyPI project does not yet exist and the upstream release has not been
  merged/tagged. The workflow is ready, but publishing requires the maintainer
  to configure PyPI Trusted Publishing for agent0ai/a0-connector and publish
  the release. The ACP Registry entry should be submitted only after that
  artifact is publicly resolvable.