chore(release): cut amplifier-agent 0.14.0

[David Koleczek (DavidKoleczek)]

Engine-only release: amplifier-agent 0.13.0 -> 0.14.0, tagged v0.14.0.

What this releases

Artifact	Tag	Moves
amplifier-agent (engine)	v0.14.0	0.13.0 -> 0.14.0
amplifier-agent-ts	—	no release; wrappers/typescript/ unchanged since wrapper-v0.7.1
amplifier-agent-py	—	no release; wrappers/python-py/ unchanged, still never published

Minor rather than patch: gemini and vllm are new valid provider.module values and new module entries in bundle.md. That is new surface, not a fix.

User-visible change

Two new providers. provider.module: "gemini" talks to Google's Gemini API as a normal key-based provider (GOOGLE_API_KEY, or GEMINI_API_KEY as the module's own fallback; default model gemini-2.5-flash). provider.module: "vllm" integrates a self-hosted or remote vLLM server for open-weight models, speaking vLLM's OpenAI-compatible Responses API rather than the Chat Completions wire. Its credential is an endpoint, not a key: VLLM_BASE_URL is required and VLLM_API_KEY is optional, since a local vLLM server commonly needs none.

serve lifecycle no longer misbehaves on Windows. Three POSIX assumptions were wrong there. Most consequentially, os.kill(pid, 0) is not a benign liveness probe on Windows: CPython maps CTRL_C_EVENT to GenerateConsoleCtrlEvent, and because CTRL_C_EVENT == 0, signal 0 delivered a real console Ctrl+C to the target's process group — serve status could interrupt the very server it was reporting on. Liveness now uses OpenProcess/WaitForSingleObject. SIGKILL escalation falls back to SIGTERM, and detached restart uses DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP. The 0600/0700 state-file permission verification is skipped on Windows, where it could never pass and previously refused to write serve.json at all; chmod is still applied and POSIX enforcement still fails closed.

Windows-authored files are read as UTF-8 with an optional BOM. A BOM-prefixed agent .md previously spawned a sub-agent with the wrong tools, or none, silently — the surviving U+FEFF made the startswith("---") frontmatter check false, so tools, hooks, model_role, and meta were dropped from the overlay with no error. A BOM-prefixed credentials.json was reported as corrupt when it was valid, and a genuinely non-UTF-8 one killed the CLI with a raw traceback out of a handler that caught only JSONDecodeError.

Windows installs need git config --global core.longpaths true first, documented in docs/INSTALL.md. Committed eval fixtures reach ~178-character paths, and uv tool install --from git+... clones into a deep temp build dir, pushing them past MAX_PATH; the checkout fails before the build starts.

Scope of impact

Engine-only. No wrapper or SDK changes, so nothing cross-component needs to land alongside this.

PROTOCOL_VERSION did not move. It stays at 0.3.0, so no wrapper pin, conformance fixture, or downstream SDK needs coordination.

Downstream: amplifier-app-opencode floor moves to 0.14.0

MIN_AGENT_VERSION goes 0.12.0 -> 0.14.0. The floor is a requirement statement, not a mirror of the latest release, and this release clears that bar on its own merits: opencode drives serve, and the Windows lifecycle fixes above are directly opencode-observable rather than engine-internal. The UTF-8/BOM credential reads and the new providers surfacing through GET /v1/models reinforce it.

That bump is not part of this PR. It is executed downstream after v0.14.0 is tagged, because AGENT_PINNED_REF resolves to f"v{MIN_AGENT_VERSION}" and pinning to a tag that does not yet exist would break launch-time self-heal. Note the cost when it lands: AGENT_HARD_FLOOR tracks the minimum, so every opencode user below it is force-reinstalled rather than self-updated.

amplifier-app-paperclip and amplifier-app-nanoclaw caret-pin amplifier-agent-ts, which this release does not touch.

Gate

make verify is green: lint, pyright src/ (0 errors), codegen staleness, cross-manifest versions, wheel contents (6/6 checks against amplifier_agent-0.14.0-py3-none-any.whl), 10/10 conformance parity fixtures, and 121 TypeScript wrapper tests.

Merging does not publish

Merging this PR publishes nothing. The release happens when v0.14.0 is pushed as a tag, which triggers the PyPI upload and the GitHub Release. Since install.sh and amplifier-agent update install from git and resolve "latest" through the GitHub Releases API, that tag is what users actually receive.