Merced AI 0.8.0

merced-ai 0.8.0

Release notes, September 28, 2026. The full list of changes is in the
changelog.

Highlights

• Harness adapter plugins. Every built-in adapter is now a HarnessSpec, and installed
  packages can add adapters through the merced_ai.harnesses entry-point group. A contract-test kit
  (merced_ai.testing.contract) checks third-party adapters. See plugins.
• Agent Client Protocol. Claude Code, Gemini CLI, Goose, and OpenCode run as ACP agents when
  their launchers are installed: replies stream, permission requests go through the AAIS approval
  dialog or a terminal prompt, and three of the four resume their own sessions. merced-ai acp
  serves a bot or a room to editors such as Zed.
• Worktree rooms. group ask/chat --worktrees gives each write-capable bot its own git
  worktree, with group diff, group apply, and group cleanup (and matching web UI views).
  Without worktrees, write-capable bots sharing a workspace now take turns.
• Cross-harness evals. merced-ai eval run sends one profile and prompt to several harnesses,
  scores deterministic checks first, and reports an optional judge separately. See
  evals.
• Reviewed OAP state inbox. State deltas are validated on arrival and applied only after
  approval. See inbox.
• Terminal approvals. When MagAgent, Loro, or an ACP agent asks for approval during ask,
  chat, or a group command, the CLI shows the request and takes one key; Deny is the default.
  Before this, those requests were denied silently on the command line.
• Prompts off the command line. Most harnesses now read the prompt from stdin or a private
  file, so long conversations no longer fail with E2BIG or a Windows command-line limit.
• Experimental A2A endpoint on the UI server. See serving.
• Web UI first run. A guide lists every detected harness with its state, offers a starter
  bot, keeps drafts typed before a bot exists, and explains a missing or stale token. Fonts are
  self-hosted.

Behavior changes

• merced-ai ui defaults to port 8773 (was 8765, which collided with loro web). Update
  bookmarks and A2A client configuration that assumed 8765.
• Requires agent-approval-interchange>=0.2.0,<0.3. Approval-presenter and run-record owners are
  recorded as aais.liveness owner identities; existing files are read and upgraded in place.
• Harness descriptors report harness_supports and broker_implements separately, and only
  broker-implemented capabilities are shown as supported. Probe JSON keeps a deprecated
  capabilities field for this release.
• Projection reports list every profile section a prompt-context projection drops.
• A security self-review of the new surfaces (see threat model) led to fixes for
  worktree path trust, symlinks in applied patches, plugins loaded from the working directory, DNS
  rebinding and request size limits on the UI server, and approval labels chosen by the harness.

MagAgent and Loro compatibility

Merced AI 0.8.0 works with earlier MagAgent and Loro releases and uses newer features when the
installed version has them. Features are detected from each harness's own help and version output.

Harness	With this version or later	Older versions
MagAgent 1.4.0	Prompt through a private file (ask --prompt-file); shell: ask asks for every command and shell: deny removes the shell tools (reported as mapped)	Prompt as an argument, subject to the size guard; shell is narrowed
Loro 0.22.0	Prompt through a private file (run --prompt-file) and run --json output	Prompt as an argument, subject to the size guard

A development build of MagAgent that still reports 1.3.x is treated as 1.3.

Upgrading

Back up .merced-ai before upgrading. Conversation, run, and presenter files from 0.7.0 load
without manual steps: 0.7.0 run journals are converted to the append-only JSON Lines format and
bare-PID owners are upgraded on first use. AGS, OAP, and AAIS document and wire formats are
unchanged; conformance results are in docs/oap-conformance.json and docs/ags-conformance.json.