Add native Antigravity and Gemini support

.agents/hooks.json

@@ -0,0 +1,41 @@
+{
+  "firstmate-sessionstart": {
+    "PreInvocation": [
+      {
+        "type": "command",
+        "command": "../bin/fm-antigravity-hook.sh sessionstart",
+        "timeout": 180
+      }
+    ]
+  },
+  "firstmate-shell-seatbelts": {
+    "PreToolUse": [
+      {
+        "matcher": "run_command",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "../bin/fm-arm-pretool-check.sh --antigravity"
+          },
+          {
+            "type": "command",
+            "command": "../bin/fm-cd-pretool-check.sh --antigravity"
+          }
+        ]
+      }
+    ]
+  },
+  "firstmate-delegation-seatbelt": {
+    "PreToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "../bin/fm-subagent-pretool-check.sh --antigravity"
+          }
+        ]
+      }
+    ]
+  }
+}

.agents/skills/harness-adapters/SKILL.md

@@ -3,7 +3,7 @@ name: harness-adapters
 description: >-
   Agent-only reference for firstmate harness operations.
   Use before spawning or recovering a crewmate or secondmate, handling a trust dialog, sending a harness-specific skill invocation, interrupting or exiting an agent, resuming an exited agent, or verifying a new harness adapter.
-  Contains verified facts for claude, codex, opencode, pi, pi-signed, grok, kimi, cursor, gemini, and muse.
+  Contains verified facts for claude, codex, opencode, pi, pi-signed, grok, kimi, cursor, gemini, muse, and antigravity.
 user-invocable: false
 metadata:
   internal: true
@@ -90,7 +90,8 @@ A new tool remains undispatchable until the `verify` plan, its harness entry, ev
     "kimi": "references/harness/kimi.md",
     "cursor": "references/harness/cursor.md",
     "gemini": "references/harness/gemini.md",
-    "muse": "references/harness/muse.md"
+    "muse": "references/harness/muse.md",
+    "antigravity": "references/harness/antigravity.md"
   }
 }
 ```

.agents/skills/harness-adapters/references/harness/antigravity.md

@@ -0,0 +1,72 @@
+# Google Antigravity CLI
+
+Google's `agy` TUI, verified end to end on 2026-09-04 with Antigravity CLI 1.1.26 on macOS.
+This is a distinct adapter from Google's separate `gemini` CLI.
+It is verified for crewmates, scouts, second mates, and interactive primary sessions.
+
+## Operating facts
+
+| Fact | Value |
+|---|---|
+| Launch | `agy --dangerously-skip-permissions --add-dir <exact-worktree> --add-dir <firstmate-hook-overlay> --model <id> --effort <low|medium|high> --prompt-interactive "<brief>"`. Second mates omit the task overlay because their own tracked `.agents/hooks.json` supplies primary hooks. |
+| Workspace | The first `--add-dir` selects the exact isolated project and makes its `AGENTS.md` and `.agents/skills/` available. Without it, terminal tools start in `~/.gemini/antigravity-cli`, not the launching shell's directory. |
+| Autonomy | `--dangerously-skip-permissions` is the documented always-proceed mode and runs terminal tools unattended. `--mode accept-edits` alone does not grant command execution in headless mode; the command is automatically denied. |
+| Marker | Tool subprocesses carry `ANTIGRAVITY_AGENT=1`. Inherited `AI_AGENT` and Pi markers are not Antigravity identity and are cleared by the canonical launch. |
+| Model | `--model <id>`; `agy models` is the authoritative current catalog. The Firstmate adapter is Gemini-only: it validates an explicit `gemini-*` id or chooses a live Gemini catalog entry, preferring the requested effort suffix. |
+| Effort | `--effort low|medium|high`; xhigh and max are unsupported and deliberately omitted. |
+| Busy state | Semantic `antigravity-hook`: task `PreInvocation` opens activity and `Stop` settles it. Herdr's native `agent get` also reports `agy` with working/idle status, and the rendered delivery token is `esc to cancel`. |
+| Turn end | The Firstmate-owned task overlay's `Stop` hook settles activity and touches `state/<id>.turn-ended`. |
+| Interrupt | One `Escape`; the active turn cancels and the TUI remains open. |
+| Exit | `/quit`, then one Enter. |
+| Skills | Antigravity automatically discovers skills under `.agents/skills/` from the added workspace. |
+| Primary | One foreground `bin/fm-watch.sh` terminal call; see `../../../../../docs/supervision-protocols/antigravity.md`. |
+
+## Version and sign-in
+
+Require `agy --version` 1.1.26 or newer.
+That release advertises the fix for repeated subagent approvals in always-proceed mode; use the vendor's `agy update` command when the installed version is older.
+Complete Antigravity's own sign-in once before dispatch.
+Firstmate never copies or embeds the account credential in a launch command.
+
+## Detection and liveness
+
+`../../../../../bin/fm-harness.sh` checks `ANTIGRAVITY_AGENT=1` before inherited Pi or other generic markers and recognizes exact `agy` process ancestry.
+Never use `AI_AGENT` as identity: a verified Antigravity tool process retained its Pi launcher's value.
+The exact executable name `agy` is also registered with the shared session-lock and tmux foreground-process classifiers.
+Herdr 0.8.0 natively reports `agent=agy` and working/idle state for the same process.
+A bare command or path merely containing the substring `agy` is not accepted as identity.
+
+## Workspace, instructions, and hooks
+
+Antigravity discovers `.agents/hooks.json`, `AGENTS.md`, and `.agents/skills/` from a directory passed with `--add-dir`.
+Hook discovery is independent of the argument's position in the repeated `--add-dir` list.
+Hook commands run with the directory containing `hooks.json` as their working directory.
+The tracked root hook injects the normal startup reminder with `PreInvocation` and gates terminal/delegation tools with `PreToolUse`.
+For workers, `fm-spawn.sh` writes `state/<id>.antigravity-hooks/.agents/hooks.json` and adds that isolated overlay after the project path, so it never writes or replaces the project's own `.agents/hooks.json`.
+`fm-control.sh relaunch` retires the old hook file before arming a replacement generation, and cleanup removes the overlay directory.
+A raw launch command receives none of this task wiring and has no trusted semantic activity state.
+
+## Composer, steering, and lifecycle
+
+Antigravity draws a `>` input row between two solid separator rows.
+The shared composer classifier accepts that shell-like glyph only inside the verified separated shape and only when the live identity probe says Antigravity; a bare `>` remains a dead shell and can never prove an empty composer.
+This preserves the ordinary durable-inbox steering path and Enter-only retry rule on tmux and Herdr.
+Lifecycle operations go only through `../../../../../bin/fm-control.sh`.
+The executable table in `../../../../../bin/fm-control-lib.sh` owns the one-Escape interrupt, `/quit` exit, task-kind support, and hook-overlay cleanup path.
+
+## Primary safety and supervision
+
+Antigravity's `PreToolUse` input is `.toolCall.name` plus `.toolCall.args.CommandLine`, and deny output is `{"decision":"deny","reason":"..."}`.
+The tracked primary hooks adapt that native contract to Firstmate's watcher-arm, persistent-directory-change, and built-in delegation guards.
+Those guards are primary-scoped and remain inert in isolated worker copies where delegation is legitimate.
+A live Gemini turn on 1.1.26 identified the built-in delegation tools as `invoke_subagent` and `send_message`; both are denied by the guard's existing delegation-shape classification in a Firstmate primary.
+Antigravity hooks are synchronous and expose no verified asynchronous background-task-to-model wake.
+The primary therefore uses the named foreground supervision protocol rather than borrowing another harness's background mechanics.
+Headless `--print` is not a primary host because it has no persistent conversation for later fleet notifications.
+
+## Verification boundary
+
+The live checks used a named disposable Herdr lab and explicit Gemini models only.
+They proved model and effort display, exact workspace tool execution, `AGENTS.md` and skill discovery, autonomous terminal execution, marker precedence, native Herdr identity, hook discovery, one-Escape interrupt, and `/quit` exit.
+No Claude-family model was selected.
+See `../../../../../docs/verification/antigravity.md` for the dated commands, counterfactuals, and remaining limitations.

AGENTS.md

@@ -97,6 +97,7 @@ state/               runtime records and signals; gitignored
   <id>.grok-turnend-token   firstmate-owned grok hook registry token for the task; removed by teardown
   <id>.kimi-turnend-token   firstmate-owned Kimi hook registry token for the task; removed by teardown
   <id>.gemini-settings.json  firstmate-owned per-task Gemini settings carrying the busy-state and turn-end hooks, reached through GEMINI_CLI_SYSTEM_SETTINGS_PATH so nothing is written into the project's own .gemini/; removed by teardown
+  <id>.antigravity-hooks/  firstmate-owned Antigravity `--add-dir` overlay carrying per-task busy-state and turn-end hooks without touching the project's own `.agents/hooks.json`; removed by teardown
   <id>.muse-session  muse busy-source binding (sessions root plus task worktree) written by fm-spawn; removed by teardown
   <id>.cursor-session  cursor busy-source binding (projects root, task worktree, prior conversations) written by fm-spawn; removed by teardown
   <id>.reconcile-nudged  epoch second of the last inventory-reconcile nudge sent to this secondmate; bin/fm-secondmate-reconcile.sh owns its per-home cooldown window
@@ -199,7 +200,7 @@ A silent bootstrap section needs no action; for any printed actionable diagnosti
 ## 4. Harness and runtime dispatch
 
 Load `harness-adapters` before every spawn or recovery and before trust handling, skill invocation, interrupt, exit, resume, or adapter verification.
-The verified harnesses are `claude`, `codex`, `opencode`, `pi`, `pi-signed`, `grok`, `kimi`, and `cursor`, plus `muse` and `gemini` for crewmates and scouts only; never dispatch on an unverified adapter.
+The verified harnesses are `claude`, `codex`, `opencode`, `pi`, `pi-signed`, `grok`, `kimi`, `cursor`, and `antigravity`, plus `muse` and `gemini` for crewmates and scouts only; never dispatch on an unverified adapter.
 If static `config/crew-harness` or `config/secondmate-harness` names an unverified adapter, report it and fall back only to a verified adapter rather than launching it.
 
 `docs/configuration.md` owns dispatch-profile and runtime-backend schemas, `bin/fm-harness.sh` owns static resolution, and `bin/fm-spawn.sh` owns launch flags and fail-closed validation.

README.md

@@ -58,7 +58,7 @@ Full detail on every feature lives in [docs/architecture.md](docs/architecture.m
 
 ### Requirements
 
-- A verified primary agent harness: Claude Code, Grok, Pi, `pi-signed`, Codex, OpenCode, or Cursor Agent CLI.
+- A verified primary agent harness: Claude Code, Grok, Pi, `pi-signed`, Codex, OpenCode, Cursor Agent CLI, or Google Antigravity CLI (`agy` 1.1.26+).
 - Git and the GitHub CLI, authenticated through `gh auth login`.
 - The CLI and dependencies for your selected runtime backend; tmux is the reference default.
 
@@ -75,6 +75,8 @@ Pick whichever one matches your subscription and workflow.
 Codex and OpenCode are also verified and supported as primary harnesses; Codex uses bounded foreground checkpoints, and OpenCode uses a TUI plugin, so both carry more harness-specific supervision tradeoffs than the three co-primaries.
 Cursor Agent CLI is verified as a primary too, using a tracked project-scope `.cursor/hooks.json` whose `stop` hook parks on the watcher between turns, closest in shape to Claude Code's.
 Launch it with `--trust`, or none of its project hooks load; it also has no turn-end hook in headless `cursor-agent -p`, so run the primary session interactively.
+Google Antigravity CLI 1.1.26+ is verified as a primary and worker harness with native Gemini model and low/medium/high effort selection.
+It uses a foreground terminal-tool supervision wait because Antigravity exposes no verified asynchronous process-to-model wake, and `fm-spawn.sh` supplies the exact isolated project, autonomous permission mode, and Firstmate-owned task hooks.
 
 ### Install and launch
 
@@ -84,7 +86,7 @@ git clone https://github.com/kunchenguid/firstmate
 cd firstmate
 ```
 
-Then launch one of the co-primary harnesses; AGENTS.md takes over from there:
+Then launch a verified primary harness; AGENTS.md takes over from there:
 
 **Claude Code**
 
@@ -106,6 +108,16 @@ pi
 FM_PI_HARNESS=pi-signed pi-signed
 ```
 
+**Google Antigravity CLI**
+
+```sh
+agy --dangerously-skip-permissions --add-dir "$PWD" --model <gemini-model> --effort low
+```
+
+Install Antigravity from [antigravity.google/download](https://antigravity.google/download), sign in once, and use `agy models` for the current model ids.
+Run `agy update` when `agy --version` is older than 1.1.26.
+The tracked `.agents/hooks.json` loads startup and primary safety hooks from this repository; use the interactive TUI rather than headless `--print` for a primary session.
+
 For Grok, `--trust` is needed once per clone so project hooks and the turn-end guard load; `/hooks-trust` inside Grok works too.
 For Pi, approve the project trust prompt once per clone on first launch so the tracked `.pi/extensions/*.ts` files auto-load.
 Pi's `/calm` toggle hides supported transcript chrome, including canonically classified Firstmate operational user rows, and uses a Calm-only animated working boat during active runs while preserving all model context and session data.
@@ -216,7 +228,7 @@ Firstmate's skills live in two separate places with different audiences:
 - [docs/gitlab-merge-watch.md](docs/gitlab-merge-watch.md) - maintainer verification for watching and merging GitLab merge requests on arbitrary instances.
 - [docs/turnend-guard.md](docs/turnend-guard.md) - the primary session's current "no turn ends blind" backstop, scope, loop safety, and compatibility limits.
 - [docs/verification/supervision.md](docs/verification/supervision.md) - active maintainer verification for session-start, guard, continuity, and wedge integrations.
-- [docs/supervision-protocols/](docs/supervision-protocols/) - rendered primary-harness watcher protocols for Claude, Codex, OpenCode, Pi and `pi-signed`, Grok, Cursor, and unknown harness fallback.
+- [docs/supervision-protocols/](docs/supervision-protocols/) - rendered primary-harness watcher protocols for Claude, Codex, OpenCode, Pi and `pi-signed`, Grok, Cursor, Antigravity, and unknown harness fallback.
 - [docs/scripts.md](docs/scripts.md) - the `bin/` toolbelt reference.
 - [docs/documentation-audiences.md](docs/documentation-audiences.md) - documentation audiences and the machine-checked placement boundary.
 - [`AGENTS.md`](AGENTS.md) - the distro's always-loaded operating contract and routing index for conditional procedures.

bin/backends/herdr.sh

@@ -2620,7 +2620,7 @@ fm_backend_herdr_capture_ansi() {  # <target> <lines>
 # ANSI pane capture (with its small-N workaround), the native `agent get`
 # identity probe, and the capability descriptor. Every shape - the bordered
 # box, the bare agent-glyph row, opencode's left-bar, and pi's
-# identity-gated separated pair (which this adapter pioneered) - now lives in
+# identity-gated separated pair (Pi and Antigravity) - now lives in
 # the shared owner (bin/fm-composer-lib.sh, fm_composer_classify_screen), so
 # a new harness shape is taught there once and every backend learns it in the
 # same commit. The muse `⟩` glyph this adapter's local bare-prompt pattern
@@ -2633,7 +2633,7 @@ fm_backend_herdr_agent_identity_raw() {  # <session> <pane> -> <agent>\t<status>
 }
 
 # fm_backend_herdr_composer_identity: the native agent identity/state probe
-# backing the shared classifier's separated (pi) shape - the genuine herdr
+# backing the shared classifier's separated shape - the genuine herdr
 # primitive no other backend has natively.
 fm_backend_herdr_composer_identity() {  # <target> -> "<agent>\t<status>"
   fm_backend_herdr_parse_target "$1" || return 1
@@ -2645,7 +2645,7 @@ fm_backend_herdr_composer_identity() {  # <target> -> "<agent>\t<status>"
 # shared classifier strip ghost/placeholder text); when it fails on an older
 # herdr, the plain capture degrades the descriptor to styled=0 rather than
 # letting ghost text be misread as typed input. Identity is fetched lazily,
-# only when the classifier reports the verdict depends on it (a pi separator
+# only when the classifier reports the verdict depends on it (a separated
 # pair below every other candidate), preserving this adapter's original
 # consult-only-when-needed behavior.
 fm_backend_herdr_composer_state() {  # <target> -> empty|pending|pending-unproven|unknown

bin/backends/tmux.sh

@@ -171,7 +171,7 @@ fm_backend_tmux_classify_process_name() {  # <path> [argv0] -> agent|shell|other
     # would classify musescore or amuse as a live agent pane. The install path
     # cannot carry it either: ~/.local/bin/muse-bin-<version> has no `muse` path
     # COMPONENT, so the fm_harness_path_name fallback below never fires for it.
-    muse|muse-bin-*) printf 'agent' ;;
+    muse|muse-bin-*|agy) printf 'agent' ;;
     *claude*|*codex*|*opencode*|*grok*|*kimi*|pi|pi-signed|pi-launcher|Pi) printf 'agent' ;;
     zsh|bash|sh|dash|ash|ksh|mksh|tcsh|csh|fish) printf 'shell' ;;
     *)

bin/fm-antigravity-hook.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# Antigravity hook adapter for Firstmate.
+#
+# Usage:
+#   fm-antigravity-hook.sh sessionstart
+#   fm-antigravity-hook.sh task-busy <state-dir> <task-id> <generation>
+#   fm-antigravity-hook.sh task-stop <state-dir> <task-id> <generation> <turn-ended-file>
+#
+# Antigravity discovers .agents/hooks.json in every --add-dir root. The task
+# launcher points one added directory at a Firstmate-owned overlay so projects'
+# own customization remains untouched. Hook stdin is consumed but never trusted
+# for task identity: spawn bakes the canonical state directory, safe task id,
+# and fresh busy generation into the isolated hook file.
+#
+# PreInvocation opens semantic busy state before the model starts or resumes.
+# Stop settles that state and publishes the ordinary turn-end edge. Sessionstart
+# reuses Firstmate's read-only startup nudge and returns Antigravity's documented
+# PreInvocation injectSteps.ephemeralMessage shape.
+set -euo pipefail
+
+SCRIPT_DIR=$(CDPATH='' cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)
+
+usage() {
+  echo "usage: $0 sessionstart | task-busy <state-dir> <task-id> <generation> | task-stop <state-dir> <task-id> <generation> <turn-ended-file>" >&2
+  exit 2
+}
+
+mode=${1:-}
+case "$mode" in
+  sessionstart)
+    [ "$#" -eq 1 ] || usage
+    cat >/dev/null
+    message=$(
+      FM_SESSIONSTART_HOOK_MODE=1 \
+        "$SCRIPT_DIR/fm-sessionstart-nudge.sh" 2>/dev/null || true
+    )
+    if [ -n "$message" ]; then
+      jq -n --arg message "$message" \
+        '{injectSteps:[{ephemeralMessage:$message}]}'
+    else
+      printf '{}\n'
+    fi
+    ;;
+  task-busy)
+    [ "$#" -eq 4 ] || usage
+    cat >/dev/null
+    "$SCRIPT_DIR/fm-busy-event.sh" apply "$2" "$3" busy \
+      --gen "$4" --source antigravity-hook --event pre-invocation >/dev/null 2>&1 || true
+    printf '{}\n'
+    ;;
+  task-stop)
+    [ "$#" -eq 5 ] || usage
+    cat >/dev/null
+    "$SCRIPT_DIR/fm-busy-event.sh" apply "$2" "$3" idle \
+      --gen "$4" --source antigravity-hook --event stop >/dev/null 2>&1 || true
+    : > "$5"
+    printf '{"decision":"stop"}\n'
+    ;;
+  *) usage ;;
+esac