v0.8.0 — 2026-08-25

Release Notes

The follow-ups from reviewing v0.7.0's warm-up thread, plus the schema contract
the MCP tools never declared. Minor rather than patch because
harken::mcp::ServerInfo gained a public field, which breaks literal
construction — the rule for picking that digit is now written down in
CLAUDE.md instead of re-derived per release.

• transcribe_status no longer misreports a warm-up in flight. It derived
  everything from a pure stat, so during the startup download it said the model
  "is NOT cached: the first transcription call will download it" — both halves
  wrong in the one window an agent is most likely to ask. The download is
  already running, and a call does not start a second one, it waits on it. The
  tool stays stat-only (that is what lets it answer "will a call stall?" without
  ever risking a download); it now reads the warm-up state alongside the stat
  and reports idle, downloading, ready or failed.
• A failed warm-up is finally visible to a client. It used to exist only as
  a stderr line, so an agent asking for status right after got a plain "not
  cached" with no hint the download had already failed once. transcribe_status
  now surfaces the recorded error.
• All three MCP tools declare an outputSchema describing the
  structuredContent they already returned, plus readOnlyHint: true and
  openWorldHint: false. A client now has a machine-readable contract for the
  structured payload and can tell these tools mutate nothing without reading
  prose. A key-set drift guard ships with them — a declared schema with nothing
  checking it is worse than no schema.
• Fixed: a panic in the warm-up thread wedged every tool call for the life
  of the process. The warm state was settled only on the happy path, so an
  unwind left it pending forever and the gate blocked on it — the client saw
  initialize and tools/list answer normally, then a tools/call that never
  returned and never errored. A drop guard now settles the state on unwind too,
  so a panic behaves like a failed download: the call is let through and the
  engine retries inline.
• Fixed: the server outlived EOF until its warm-up download finished. A
  client that spawns and kills MCP servers (probing a config, restarting after
  an edit) left one live process per attempt, each streaming up to 466 MB with
  nothing to stop it. The thread is now detached at EOF, bounding shutdown. An
  abandoned download can never corrupt the cache — only a Content-Length- and
  SHA-256-verified file is renamed into place — but it does leave its .partial
  file behind, which is inert.
• 158 → 166 tests.

Breaking

• harken::mcp::ServerInfo has a new public field, warm: Option<Warmth>.
  Construct it with ..ServerInfo::default(), or pass Some(warmth) to have
  transcribe_status report the warm-up. CLI and MCP surfaces are unaffected —
  no flag, tool or argument changed shape.

Install harken 0.8.0

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/montezuma-p/harken/releases/download/v0.8.0/harken-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/montezuma-p/harken/releases/download/v0.8.0/harken-installer.ps1 | iex"

Download harken 0.8.0

File	Platform	Checksum
harken-aarch64-apple-darwin.tar.xz	Apple Silicon macOS	checksum
harken-x86_64-apple-darwin.tar.xz	Intel macOS	checksum
harken-x86_64-pc-windows-msvc.zip	x64 Windows	checksum
harken-aarch64-unknown-linux-gnu.tar.xz	ARM64 Linux	checksum
harken-x86_64-unknown-linux-gnu.tar.xz	x64 Linux	checksum