diff --git a/src/claire/agent/__init__.py b/src/claire/agent/__init__.py
new file mode 100644
index 0000000..7bd0877
--- /dev/null
+++ b/src/claire/agent/__init__.py
@@ -0,0 +1,30 @@
+"""Headless per-host agent — the Linux counterpart to the macOS tray.
+
+Runs inside `create_app(peer_mode=True)` on apricot/black as a `systemd --user`
+service. It drives background loops (sync now; supervisor + telemetry in a
+later phase) but never touches the orchestrator lifecycle.
+"""
+
+from __future__ import annotations
+
+import asyncio
+from pathlib import Path
+
+
+def start_agent_loops(
+    *, config_path: Path | None, db_path: Path | None
+) -> list[asyncio.Task]:
+    """Start the agent's background loops; return them so the lifespan can
+    cancel them on shutdown.
+
+    Phase 1: scheduled peer sync only. Supervisor + telemetry loops are
+    added here in a later phase.
+    """
+    from .sync_loop import sync_loop
+
+    return [
+        asyncio.create_task(sync_loop(config_path=config_path, db_path=db_path)),
+    ]
+
+
+__all__ = ["start_agent_loops"]
diff --git a/src/claire/agent/sync_loop.py b/src/claire/agent/sync_loop.py
new file mode 100644
index 0000000..d9cc1d6
--- /dev/null
+++ b/src/claire/agent/sync_loop.py
@@ -0,0 +1,67 @@
+"""Scheduled peer-sync loop for the headless `claire agent`.
+
+Push B's substrate (`sync.sync_peer`, `/api/v1/sync/*`) is one-shot via the
+`claire sync` CLI. The agent adds the missing *scheduled* loop: every
+`agent.sync_interval_s`, converge with each configured peer. Star topology —
+peer hosts (apricot/black) sync only to plum, which fans changes out; so each
+peer's `[[peers]]` lists plum, and apricot↔black converge in two hops.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+import time
+from datetime import datetime, timezone
+from pathlib import Path
+
+logger = logging.getLogger(__name__)
+
+
+async def sync_loop(*, config_path: Path | None, db_path: Path | None) -> None:
+    from ..config import load_or_init
+    from ..sync import sync_peer
+
+    cfg = load_or_init(config_path)
+    interval = cfg.agent.sync_interval_s
+    # The agent serves its own API on loopback:agent.port; sync_peer POSTs
+    # ingested events back to ourselves and reads our own cursor there.
+    local_base = f"http://127.0.0.1:{cfg.agent.port}"
+    if not cfg.peers:
+        logger.warning(
+            "agent sync loop: no [[peers]] configured — nothing to sync (idle)"
+        )
+    logger.info(
+        "agent sync loop enabled (every %ds, %d peer(s))", interval, len(cfg.peers)
+    )
+
+    while True:
+        try:
+            await asyncio.sleep(interval)
+            # Reload so peer/secret/interval edits apply without a restart.
+            cfg = load_or_init(config_path)
+            for peer in cfg.peers:
+                try:
+                    result = await asyncio.to_thread(
+                        sync_peer,
+                        peer,
+                        local_base=local_base,
+                        local_secret=cfg.sync_secret,
+                    )
+                    logger.info(
+                        "sync %s: pulled=%d pushed=%d",
+                        peer.url, result.pulled, result.pushed,
+                    )
+                except Exception as exc:  # noqa: BLE001
+                    # A 401 here almost always means clock skew vs the HMAC
+                    # window (SIG_MAX_SKEW_SEC) — log local time so it's
+                    # diagnosable. Other failures (peer down) are transient.
+                    logger.warning(
+                        "sync %s failed (local time %s, epoch %.0f): %s",
+                        peer.url,
+                        datetime.now(timezone.utc).isoformat(),
+                        time.time(),
+                        exc,
+                    )
+        except asyncio.CancelledError:
+            return
diff --git a/src/claire/cli.py b/src/claire/cli.py
index 2a496d8..7960d8c 100644
--- a/src/claire/cli.py
+++ b/src/claire/cli.py
@@ -27,9 +27,11 @@ app = typer.Typer(help="Claire — project manager for the Claude agent fleet.",
 project_app = typer.Typer(help="Manage projects.")
 task_app = typer.Typer(help="Manage tasks.")
 orchestrator_app = typer.Typer(help="Manage the orchestrator Claude session.")
+agent_app = typer.Typer(help="Headless peer-node daemon (Linux worker hosts).")
 app.add_typer(project_app, name="project")
 app.add_typer(task_app, name="task")
 app.add_typer(orchestrator_app, name="orchestrator")
+app.add_typer(agent_app, name="agent")
 
 console = Console()
 
@@ -122,6 +124,32 @@ def web(
     serve(host=host, port=port, no_build=no_build)
 
 
+@agent_app.command("run")
+def agent_run(
+    host: Annotated[str, typer.Option("--host")] = "127.0.0.1",
+    port: Annotated[int | None, typer.Option("--port")] = None,
+) -> None:
+    """Run the headless peer-node daemon (peer mode — no orchestrator/SPA/MCP).
+
+    Serves /api/v1/* (incl. /sync/*) on loopback + drives the agent loops
+    (sync now; supervisor + telemetry later). Deployed as a systemd --user
+    unit on apricot/black.
+    """
+    import uvicorn
+
+    from .web.app import create_app
+
+    cfg = load_or_init()
+    bind_port = port or cfg.agent.port
+    console.print(
+        f"[bold]claire agent[/bold] (peer mode) on http://{host}:{bind_port} — "
+        f"{len(cfg.peers)} peer(s), sync every {cfg.agent.sync_interval_s}s"
+    )
+    uvicorn.run(
+        create_app(peer_mode=True), host=host, port=bind_port, log_level="info"
+    )
+
+
 # ---------------------------------------------------------------------------
 # SPA build management
 # ---------------------------------------------------------------------------
diff --git a/src/claire/config.py b/src/claire/config.py
index afaac13..2dd8ca1 100644
--- a/src/claire/config.py
+++ b/src/claire/config.py
@@ -51,6 +51,25 @@ class WebConfig(_Strict):
     port: int = Field(default=8765, ge=1, le=65535)
 
 
+class AgentConfig(_Strict):
+    """Settings for the headless Linux peer-node daemon (`claire agent run`).
+
+    Only consumed on apricot/black; harmless defaults on plum (the agent
+    isn't run there). The daemon binds loopback on `port`, syncs with each
+    configured peer every `sync_interval_s`, samples host telemetry every
+    `telemetry_interval_s`, and supervises local worker sessions (a session
+    with a live tmux pane but JSONL mtime older than `wedge_threshold_s` is
+    "wedged"). Respawn of wedged sessions stays OFF unless explicitly enabled.
+    """
+
+    port: int = Field(default=8766, ge=1, le=65535)
+    sync_interval_s: int = Field(default=120, ge=10, le=86400)
+    telemetry_interval_s: int = Field(default=60, ge=10, le=3600)
+    wedge_threshold_s: int = Field(default=300, ge=60, le=7200)
+    supervisor_enable: bool = True
+    supervisor_allow_respawn: bool = False
+
+
 class OrchestratorConfig(_Strict):
     """Settings for the live Claude session backing the orchestrator chat.
 
@@ -153,6 +172,7 @@ class ClaireConfig(_Strict):
     orchestrator: OrchestratorConfig = Field(default_factory=OrchestratorConfig)
     budget: BudgetConfig = Field(default_factory=BudgetConfig)
     limits: LimitsConfig = Field(default_factory=LimitsConfig)
+    agent: AgentConfig = Field(default_factory=AgentConfig)
     # The canonical label this machine identifies as in dispatch + session
     # records. `None` falls back to the short form of `socket.gethostname()`
     # (first dot-segment, lowercased). Set explicitly to override (e.g. on a
@@ -287,6 +307,19 @@ def _serialize(cfg: ClaireConfig) -> str:
                 f'"{h}" = {c}' for h, c in sorted(lim.per_host.items())
             )
             lines.append(f"per_host = {{ {inner} }}")
+    # Emit [agent] only when it differs from defaults (peer hosts only).
+    ag = cfg.agent
+    if ag != AgentConfig():
+        lines.append("")
+        lines.append("[agent]")
+        lines.append(f"port = {ag.port}")
+        lines.append(f"sync_interval_s = {ag.sync_interval_s}")
+        lines.append(f"telemetry_interval_s = {ag.telemetry_interval_s}")
+        lines.append(f"wedge_threshold_s = {ag.wedge_threshold_s}")
+        lines.append(f"supervisor_enable = {str(ag.supervisor_enable).lower()}")
+        lines.append(
+            f"supervisor_allow_respawn = {str(ag.supervisor_allow_respawn).lower()}"
+        )
     for h in cfg.known_hosts:
         lines.append("")
         lines.append("[[known_hosts]]")
diff --git a/src/claire/web/app.py b/src/claire/web/app.py
index 704d26e..b86bb2f 100644
--- a/src/claire/web/app.py
+++ b/src/claire/web/app.py
@@ -38,6 +38,7 @@ def create_app(
     config_path: Path | None = None,
     db_path: Path | None = None,
     sync_secret: Any = _USE_CONFIG,
+    peer_mode: bool = False,
 ) -> FastAPI:
     """Build a FastAPI app.
 
@@ -48,12 +49,22 @@ def create_app(
     `sync_secret` overrides the per-config value; default sentinel means
     "read from config at request-validation time" (production behavior).
     Pass an explicit `None` or string to pin for tests.
+
+    `peer_mode` builds a headless PEER NODE (the Linux `claire agent`): it
+    serves the `/api/v1/*` API (notably `/sync/*`) and runs the agent loops
+    (sync + supervisor + telemetry), but NEVER spawns/supervises the
+    orchestrator, runs rounds, or mounts the MCP server / SPA. Making it a
+    factory argument (not a config key) structurally guarantees a peer can't
+    accidentally become a second orchestrator.
     """
     # Build the MCP sub-app eagerly so we can chain its lifespan into the
     # parent's — streamable HTTP relies on a task group started in that
     # lifespan, and Starlette's `mount()` does not invoke sub-app lifespans.
-    from ..orchestrator.mcp_server import asgi_app as mcp_asgi_app
-    mcp_app = mcp_asgi_app()
+    # Peer nodes don't serve MCP, so skip it entirely.
+    mcp_app = None
+    if not peer_mode:
+        from ..orchestrator.mcp_server import asgi_app as mcp_asgi_app
+        mcp_app = mcp_asgi_app()
 
     @asynccontextmanager
     async def lifespan(_app: FastAPI):
@@ -67,7 +78,22 @@ def create_app(
           tmux dies mid-session (e.g. apricot tmux segfault).
         - Both are fire-and-forget; failures log a warning but never abort
           uvicorn — the chat UI surfaces "not configured" until recovery.
+
+        In `peer_mode`, none of the above runs: a peer node only drives the
+        agent loops (sync + supervisor + telemetry) and never touches the
+        orchestrator lifecycle or the MCP sub-app.
         """
+        if peer_mode:
+            from ..agent import start_agent_loops
+
+            tasks = start_agent_loops(config_path=config_path, db_path=db_path)
+            try:
+                yield
+            finally:
+                for t in tasks:
+                    t.cancel()
+            return
+
         from ..orchestrator.bootstrap import ensure_running
 
         HEARTBEAT_SECONDS = 60
@@ -153,11 +179,12 @@ def create_app(
     from .chat import stream as chat_stream
     app.include_router(api.router)
     app.include_router(chat_stream.router)
-    # Claire MCP server — orchestrator's .mcp.json points here.
-    app.mount("/mcp", mcp_app, name="mcp")
-    # React SPA (catch-all). Order matters: mounted LAST so the explicit
-    # routers + /assets static mount take precedence on matching paths.
-    _mount_spa(app)
+    if not peer_mode:
+        # Claire MCP server — orchestrator's .mcp.json points here.
+        app.mount("/mcp", mcp_app, name="mcp")
+        # React SPA (catch-all). Order matters: mounted LAST so the explicit
+        # routers + /assets static mount take precedence on matching paths.
+        _mount_spa(app)
     return app
 
 
diff --git a/tests/test_agent_config.py b/tests/test_agent_config.py
new file mode 100644
index 0000000..db75e2c
--- /dev/null
+++ b/tests/test_agent_config.py
@@ -0,0 +1,27 @@
+"""AgentConfig serialize/deserialize round-trip via the hand-rolled _serialize."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from claire.config import AgentConfig, ClaireConfig, _serialize, load_or_init
+
+
+def test_agent_section_omitted_when_default() -> None:
+    cfg = ClaireConfig(machine_id="m")
+    assert "[agent]" not in _serialize(cfg)
+
+
+def test_agent_config_roundtrip(tmp_path: Path) -> None:
+    p = tmp_path / "claire.toml"
+    cfg = load_or_init(p)  # fresh: mints machine_id + sync_secret, writes file
+    mutated = cfg.model_copy(
+        update={"agent": AgentConfig(sync_interval_s=30, supervisor_allow_respawn=True)}
+    )
+    p.write_text(_serialize(mutated), encoding="utf-8")
+
+    reloaded = load_or_init(p)
+    assert "[agent]" in p.read_text()
+    assert reloaded.agent.sync_interval_s == 30
+    assert reloaded.agent.supervisor_allow_respawn is True
+    assert reloaded.agent.port == 8766  # default preserved across round-trip
diff --git a/tests/test_agent_peer_mode.py b/tests/test_agent_peer_mode.py
new file mode 100644
index 0000000..20192cb
--- /dev/null
+++ b/tests/test_agent_peer_mode.py
@@ -0,0 +1,41 @@
+"""Peer-mode app: serves the sync API, never becomes a second orchestrator.
+
+Structural guarantee — `create_app(peer_mode=True)` must serve /api/v1/* (incl.
+/sync/*) but NOT mount MCP/SPA and NOT bootstrap the orchestrator.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from fastapi.testclient import TestClient
+
+from claire.web.app import create_app
+
+
+def test_peer_mode_serves_sync_but_not_orchestrator(tmp_path: Path, monkeypatch) -> None:
+    # Spy: if peer mode ever bootstrapped the orchestrator, this trips.
+    import claire.orchestrator.bootstrap as boot
+
+    called = {"v": False}
+
+    def _spy(**_kw):
+        called["v"] = True
+        return None
+
+    monkeypatch.setattr(boot, "ensure_running", _spy)
+
+    app = create_app(
+        config_path=tmp_path / "claire.toml",
+        db_path=tmp_path / "claire.db",
+        sync_secret=None,  # disable HMAC so the route returns 200, not 401
+        peer_mode=True,
+    )
+    with TestClient(app) as client:  # `with` runs the lifespan
+        assert client.get("/api/v1/health").status_code == 200
+        # /sync/* IS served in peer mode (200 with auth disabled).
+        assert client.get("/api/v1/sync/cursor").status_code == 200
+        # MCP + SPA are NOT mounted in peer mode.
+        assert client.get("/mcp/").status_code == 404
+
+    assert called["v"] is False  # orchestrator never bootstrapped
diff --git a/tests/test_db.py b/tests/test_db.py
index 1ed971c..cb1065a 100644
--- a/tests/test_db.py
+++ b/tests/test_db.py
@@ -11,7 +11,7 @@ def test_migrate_is_idempotent() -> None:
         "0001_initial", "0002_chat", "0003_pm", "0004_fleet",
         "0003_pm_alter", "0005_session_liveness", "0006_project_org",
         "0007_usage", "0008_task_blocked_by", "0009_decisions",
-        "0010_role_clare_to_claire",
+        "0010_role_clare_to_claire", "0011_host_telemetry",
     ]
     assert second == []  # already applied