bot_bottle/backend/macos_container/enumerate.py

@@ -8,7 +8,11 @@ from ...bottle_state import read_metadata
 from .. import ActiveAgent
 from .infra import INFRA_NAME
 
-_PREFIX = "bot-bottle-"
+# The name every agent container carries: `bot-bottle-<slug>`. Exported
+# because callers that act on a running bottle (gateway-host rewrites,
+# registry reconciliation) have to map an enumerated slug back to a
+# container name.
+CONTAINER_NAME_PREFIX = "bot-bottle-"
 # The shared per-host infra container carries the same prefix as agent
 # containers but is infrastructure, not a bottle — one control plane + gateway
 # serves every agent, so listing it as an agent would invent one per host.
@@ -26,9 +30,9 @@ def enumerate_active() -> list[ActiveAgent]:
         return []
     out: list[ActiveAgent] = []
     for name in sorted(line.strip() for line in result.stdout.splitlines()):
-        if not name.startswith(_PREFIX) or name in _INFRA_NAMES:
+        if not name.startswith(CONTAINER_NAME_PREFIX) or name in _INFRA_NAMES:
             continue
-        slug = name[len(_PREFIX):]
+        slug = name[len(CONTAINER_NAME_PREFIX):]
         metadata = read_metadata(slug)
         out.append(ActiveAgent(
             backend_name="macos-container",

bot_bottle/backend/macos_container/gateway_hosts.py

@@ -0,0 +1,96 @@
+"""Stable gateway name for macOS agents, via each bottle's `/etc/hosts`.
+
+The shared gateway's address is assigned by vmnet's DHCP and changes whenever
+the infra container is recreated — a source-hash bump, an image upgrade, a
+crash. Every agent-facing URL (egress proxy, git-http, supervise) embeds that
+address, and the proxy URL reaches the agent as **process environment** at
+`container exec` time. A running process's `environ` cannot be rewritten from
+outside, so a moved gateway used to strand every running bottle permanently:
+not degraded, unreachable, until the bottle was relaunched and its session
+thrown away.
+
+So the agent never learns the address. It is given a stable *name*
+(`GATEWAY_HOSTNAME`) in every URL, resolved through its own `/etc/hosts`.
+Unlike `environ`, that is a file — it can be rewritten inside a container that
+is already running, so a gateway that comes back at a new address is picked up
+by live bottles instead of orphaning them.
+
+Apple Container 1.0 offers no container-name DNS on a user network (the only
+nameserver an agent sees is vmnet's, which does not know container names) and
+`container run` has no `--add-host`, so the entry is written by exec after the
+container starts.
+
+Writing it needs root, and the agent runs as `node`: the agent therefore
+cannot repoint its own gateway name, while the host (which drives `container
+exec --user root`) can. That asymmetry is deliberate — keep it.
+"""
+
+from __future__ import annotations
+
+from ...log import warn
+from . import util as container_mod
+from .enumerate import CONTAINER_NAME_PREFIX, enumerate_active
+
+# The name every agent-facing gateway URL uses. Must not collide with a real
+# DNS name the agent might resolve; it is bottle-local by construction.
+GATEWAY_HOSTNAME = "bot-bottle-gateway"
+
+# Marker so the rewrite is idempotent and only ever touches our own line —
+# the rest of /etc/hosts (localhost, the container's own name) is preserved.
+_MARKER = "# bot-bottle gateway"
+
+
+def _rewrite_script(gateway_ip: str) -> str:
+    """A shell one-liner that replaces our managed line in `/etc/hosts`.
+
+    Rewrites in place via a temp file + `cat` rather than `mv`, so the file
+    keeps its original inode, ownership, and mode — a bind-mounted or
+    pre-created `/etc/hosts` must not be replaced by a root-owned 0644 copy
+    that the runtime then refuses to update.
+    """
+    return (
+        "set -e; "
+        f"grep -v '{_MARKER}' /etc/hosts > /tmp/.bb-hosts || true; "
+        f"printf '%s %s %s\\n' '{gateway_ip}' '{GATEWAY_HOSTNAME}' "
+        f"'{_MARKER}' >> /tmp/.bb-hosts; "
+        "cat /tmp/.bb-hosts > /etc/hosts; "
+        "rm -f /tmp/.bb-hosts"
+    )
+
+
+def set_gateway_host(container_name: str, gateway_ip: str) -> None:
+    """Point `GATEWAY_HOSTNAME` at `gateway_ip` inside one running container.
+
+    Must run before the agent is exec'd: the agent's proxy URL names the
+    gateway, so the entry has to exist for its first connection. Idempotent —
+    re-running with the same address is a no-op in effect.
+    """
+    container_mod.exec_container_as_root(
+        container_name, ["sh", "-c", _rewrite_script(gateway_ip)],
+    )
+
+
+def refresh_gateway_host(gateway_ip: str) -> list[str]:
+    """Re-point every running bottle at the current gateway address.
+
+    Called once the shared gateway is known to be up, so a bottle stranded by
+    an earlier gateway restart re-attaches instead of needing a relaunch.
+    Returns the containers updated.
+
+    Best-effort per bottle: one container that refuses the write (already
+    exiting, say) must not stop the others from being repaired, and must not
+    fail the launch that triggered the sweep.
+    """
+    updated: list[str] = []
+    for agent in enumerate_active():
+        name = f"{CONTAINER_NAME_PREFIX}{agent.slug}"
+        try:
+            set_gateway_host(name, gateway_ip)
+            updated.append(name)
+        # One bad bottle must not stop the sweep, so this is deliberately broad.
+        except Exception as e:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+            warn(f"could not re-point {name} at the gateway: {e}")
+    return updated
+
+
+__all__ = ["GATEWAY_HOSTNAME", "set_gateway_host", "refresh_gateway_host"]

bot_bottle/backend/macos_container/launch.py

@@ -59,6 +59,11 @@ from ..docker.egress import EGRESS_PORT
 from ..util import AGENT_CA_BUNDLE, AGENT_CA_PATH
 from . import util as container_mod
 from .bottle import MacosContainerBottle
+from .gateway_hosts import (
+    GATEWAY_HOSTNAME,
+    refresh_gateway_host,
+    set_gateway_host,
+)
 from .bottle_plan import MacosContainerBottlePlan
 from .consolidated_launch import (
     GatewayEndpoint,
@@ -100,6 +105,11 @@ def launch(
         # Step 1: the per-host singletons. Must precede the agent run — its
         # proxy env needs the gateway's address at `container run` time.
         endpoint = ensure_gateway()
+        # The gateway's address may have changed since these bottles launched
+        # (any infra recreate re-runs DHCP). They name the gateway rather than
+        # address it, so re-pointing /etc/hosts re-attaches them in place
+        # instead of leaving them stranded until relaunch.
+        refresh_gateway_host(endpoint.gateway_ip)
 
         # Step 2: mint this bottle's deploy keys, then point it at the SHARED
         # gateway's CA + git-http/supervise ports.
@@ -117,6 +127,9 @@ def launch(
         # attribution key; `--cap-drop CAP_NET_RAW` at run is what makes it
         # unforgeable. Poll: `container run --detach` can return before vmnet's
         # DHCP has assigned the address.
+        # Resolve the gateway name before anything execs: every agent-facing
+        # URL uses it, so the entry must exist for the first connection.
+        set_gateway_host(plan.container_name, endpoint.gateway_ip)
         source_ip = container_mod.wait_container_ipv4_on_network(
             plan.container_name, endpoint.network,
         )
@@ -231,13 +244,20 @@ def _stamp_agent_urls(
 ) -> MacosContainerBottlePlan:
     """Point the agent's git-gate insteadOf rewrites + supervise MCP at the
     shared gateway's ports. Both bypass the egress proxy (NO_PROXY covers the
-    gateway address)."""
+    gateway name).
+
+    Addressed by `GATEWAY_HOSTNAME`, never by IP: these URLs are baked into
+    the agent's gitconfig and MCP config at provision time, so an address here
+    would strand the bottle the moment the gateway moved. The name is resolved
+    per connection through `/etc/hosts`, which stays rewritable while the
+    bottle runs."""
+    del endpoint  # addressed by name; the address reaches the bottle via /etc/hosts
     git_gate_url = (
-        f"http://{endpoint.gateway_ip}:{_GIT_HTTP_PORT}"
+        f"http://{GATEWAY_HOSTNAME}:{_GIT_HTTP_PORT}"
         if plan.git_gate_plan.upstreams else ""
     )
     supervise_url = (
-        f"http://{endpoint.gateway_ip}:{SUPERVISE_PORT}/"
+        f"http://{GATEWAY_HOSTNAME}:{SUPERVISE_PORT}/"
         if plan.supervise_plan is not None else ""
     )
     return dataclasses.replace(
@@ -247,19 +267,25 @@ def _stamp_agent_urls(
     )
 
 
-def _proxy_url(gateway_ip: str, identity_token: str = "") -> str:
+def _proxy_url(identity_token: str = "") -> str:
     """The agent's egress proxy URL. The identity token rides as proxy
     credentials — the gateway reads Proxy-Authorization, resolves the
     (source_ip, token) pair against the control plane, and strips it before
-    upstream. Without a valid pair `/resolve` denies the request (#366)."""
+    upstream. Without a valid pair `/resolve` denies the request (#366).
+
+    Names the gateway rather than addressing it: this URL reaches the agent as
+    process environment, which cannot be rewritten once the agent is running,
+    so an address baked here is unfixable if the gateway moves."""
     cred = f"bottle:{identity_token}@" if identity_token else ""
-    return f"http://{cred}{gateway_ip}:{EGRESS_PORT}"
+    return f"http://{cred}{GATEWAY_HOSTNAME}:{EGRESS_PORT}"
 
 
-def _no_proxy(gateway_ip: str) -> str:
+def _no_proxy() -> str:
     # git-http + supervise live on the gateway and must NOT go through the
-    # egress proxy — the agent reaches them directly by its address.
-    return f"localhost,127.0.0.1,{gateway_ip}"
+    # egress proxy — the agent reaches them directly by name. Deliberately
+    # address-free: NO_PROXY is baked into the run-time env and is therefore
+    # just as unfixable as the proxy URL if the gateway moves.
+    return f"localhost,127.0.0.1,{GATEWAY_HOSTNAME}"
 
 
 def _identity_proxy_env(
@@ -276,7 +302,8 @@ def _identity_proxy_env(
     `_agent_env_entries`."""
     if not identity_token:
         return {}
-    url = _proxy_url(endpoint.gateway_ip, identity_token)
+    del endpoint  # the gateway is named, not addressed
+    url = _proxy_url(identity_token)
     return {
         "HTTPS_PROXY": url, "HTTP_PROXY": url,
         "https_proxy": url, "http_proxy": url,
@@ -338,7 +365,7 @@ def _agent_env_entries(
     # silently dropping attribution for. Without it a process that egresses
     # before the exec-time env still fails closed — the agent network is
     # host-only, so there is no route off it except the gateway.
-    no_proxy = _no_proxy(endpoint.gateway_ip)
+    no_proxy = _no_proxy()
     env = [
         f"NO_PROXY={no_proxy}",
         f"no_proxy={no_proxy}",

bot_bottle/backend/macos_container/util.py

@@ -360,6 +360,21 @@ def exec_container(name: str, argv: list[str]) -> None:
         )
 
 
+def exec_container_as_root(name: str, argv: list[str]) -> None:
+    """`exec_container`, but as uid 0 inside the container.
+
+    For host-driven maintenance the agent itself must not be able to perform —
+    rewriting `/etc/hosts` to point the gateway name at an address. The agent
+    runs as `node`, so it cannot repoint its own gateway; the host can.
+    """
+    result = _run_container_op([_CONTAINER, "exec", "--user", "root", name, *argv])
+    if result.returncode != 0:
+        die(
+            f"container exec (root) in {name} failed: "
+            f"{(result.stderr or '').strip() or '<no stderr>'}"
+        )
+
+
 def _run_container_op(cmd: list[str]) -> subprocess.CompletedProcess[str]:
     result = subprocess.run(
         cmd,

tests/unit/test_macos_container_launch_wiring.py

@@ -17,6 +17,7 @@ from unittest.mock import patch
 from bot_bottle.backend.macos_container.bottle import MacosContainerBottle
 from bot_bottle.backend.macos_container.bottle_plan import MacosContainerBottlePlan
 from bot_bottle.backend.macos_container.consolidated_launch import GatewayEndpoint
+from bot_bottle.backend.macos_container.gateway_hosts import GATEWAY_HOSTNAME
 from bot_bottle.backend.macos_container.launch import (
     _agent_run_argv,
     _identity_proxy_env,
@@ -128,7 +129,13 @@ class TestAgentRunArgv(unittest.TestCase):
         """git-http + supervise live on the gateway and must be reached
         directly, not through its own egress proxy."""
         entry = next(a for a in self.argv if a.startswith("NO_PROXY="))
-        self.assertIn("192.168.128.3", entry)
+        self.assertIn(GATEWAY_HOSTNAME, entry)
+
+    def test_no_proxy_names_the_gateway_and_never_addresses_it(self) -> None:
+        """NO_PROXY is baked into the run-time env, so an address here is as
+        unfixable as the proxy URL if the gateway moves."""
+        entry = next(a for a in self.argv if a.startswith("NO_PROXY="))
+        self.assertNotIn("192.168.128.3", entry)
 
     def test_forwarded_secrets_stay_off_argv(self) -> None:
         """Bare name → inherited from the run process env, so the value never
@@ -146,7 +153,7 @@ class TestIdentityTokenDelivery(unittest.TestCase):
     def test_exec_env_carries_the_token_as_proxy_credentials(self) -> None:
         env = _identity_proxy_env(_endpoint(), "s3cret")
         self.assertEqual(
-            "http://bottle:s3cret@192.168.128.3:9099", env["HTTP_PROXY"],
+            f"http://bottle:s3cret@{GATEWAY_HOSTNAME}:9099", env["HTTP_PROXY"],
         )
         self.assertEqual(env["HTTP_PROXY"], env["https_proxy"])
 
@@ -214,7 +221,7 @@ class TestPlanIdentityToken(unittest.TestCase):
         self.assertIn("HTTP_PROXY", argv)
         self.assertNotIn("s3cret", " ".join(argv))
         self.assertEqual(
-            "http://bottle:s3cret@192.168.128.3:9099", kwargs["env"]["HTTP_PROXY"],
+            f"http://bottle:s3cret@{GATEWAY_HOSTNAME}:9099", kwargs["env"]["HTTP_PROXY"],
         )
 
 

tests/unit/test_macos_container_util.py

@@ -272,6 +272,30 @@ resolver #2
                 ),
             )
 
+    def test_exec_container_as_root_selects_root_user(self):
+        completed = util.subprocess.CompletedProcess(
+            args=[], returncode=0, stdout="", stderr="",
+        )
+        with patch.object(util, "_run_container_op", return_value=completed) as run:
+            util.exec_container_as_root("bot-bottle-demo", ["true"])
+
+        run.assert_called_once_with([
+            "container", "exec", "--user", "root", "bot-bottle-demo", "true",
+        ])
+
+    def test_exec_container_as_root_reports_failure(self):
+        failed = util.subprocess.CompletedProcess(
+            args=[], returncode=1, stdout="", stderr="permission denied\n",
+        )
+        with patch.object(util, "_run_container_op", return_value=failed), \
+             patch.object(util, "die", side_effect=SystemExit("die")) as die:
+            with self.assertRaises(SystemExit):
+                util.exec_container_as_root("bot-bottle-demo", ["true"])
+
+        die.assert_called_once_with(
+            "container exec (root) in bot-bottle-demo failed: permission denied",
+        )
+
 
 def _completed(stdout: str, returncode: int = 0):
     return util.subprocess.CompletedProcess(args=[], returncode=returncode, stdout=stdout, stderr="")

tests/unit/test_macos_gateway_hosts.py

@@ -0,0 +1,140 @@
+"""Unit: stable gateway name via each bottle's /etc/hosts (issue #443).
+
+The gateway's address moves whenever the infra container is recreated. Agents
+name it instead of addressing it, and the name resolves through `/etc/hosts` —
+a file, so it stays rewritable while the bottle runs, unlike the `environ` the
+proxy URL is delivered in.
+"""
+
+from __future__ import annotations
+
+import unittest
+from types import SimpleNamespace
+from unittest.mock import patch
+
+from bot_bottle.backend.macos_container.gateway_hosts import (
+    GATEWAY_HOSTNAME,
+    refresh_gateway_host,
+    set_gateway_host,
+)
+
+_MOD = "bot_bottle.backend.macos_container.gateway_hosts"
+
+
+class TestSetGatewayHost(unittest.TestCase):
+    def _script(self, exec_root: object) -> str:
+        argv = exec_root.call_args.args[1]  # type: ignore[attr-defined]
+        self.assertEqual(["sh", "-c"], argv[:2])
+        return argv[2]
+
+    def test_writes_the_address_against_the_stable_name(self) -> None:
+        with patch(f"{_MOD}.container_mod.exec_container_as_root") as ex:
+            set_gateway_host("bot-bottle-demo", "192.168.128.19")
+        self.assertEqual("bot-bottle-demo", ex.call_args.args[0])
+        script = self._script(ex)
+        self.assertIn("192.168.128.19", script)
+        self.assertIn(GATEWAY_HOSTNAME, script)
+
+    def test_runs_as_root_so_the_agent_cannot_repoint_itself(self) -> None:
+        """The agent runs as `node`. If it could rewrite /etc/hosts it could
+        aim its own gateway name elsewhere, so the write must go through the
+        root-only helper."""
+        with patch(f"{_MOD}.container_mod.exec_container_as_root") as ex:
+            set_gateway_host("bot-bottle-demo", "10.0.0.1")
+        ex.assert_called_once()
+
+    def test_is_idempotent_by_removing_its_own_line_first(self) -> None:
+        """Re-pointing must replace the managed entry, not append a second one
+        — two entries for the same name would resolve by luck of ordering."""
+        with patch(f"{_MOD}.container_mod.exec_container_as_root") as ex:
+            set_gateway_host("bot-bottle-demo", "10.0.0.1")
+        self.assertIn("grep -v", self._script(ex))
+
+    def test_preserves_the_rest_of_the_hosts_file(self) -> None:
+        """localhost and the container's own name must survive the rewrite."""
+        with patch(f"{_MOD}.container_mod.exec_container_as_root") as ex:
+            set_gateway_host("bot-bottle-demo", "10.0.0.1")
+        script = self._script(ex)
+        # Filter-and-append, never a truncating write of just our line.
+        self.assertIn("/etc/hosts >", script)
+        self.assertIn(">> /tmp/.bb-hosts", script)
+
+    def test_keeps_the_original_inode(self) -> None:
+        """`cat >` rather than `mv`: a pre-created /etc/hosts must keep its
+        ownership and mode, not be replaced by a root-owned copy."""
+        script = None
+        with patch(f"{_MOD}.container_mod.exec_container_as_root") as ex:
+            set_gateway_host("bot-bottle-demo", "10.0.0.1")
+            script = self._script(ex)
+        self.assertIn("cat /tmp/.bb-hosts > /etc/hosts", script)
+        self.assertNotIn("mv ", script)
+
+
+class TestRefreshGatewayHost(unittest.TestCase):
+    """The re-attach sweep: bottles stranded by an earlier gateway restart get
+    re-pointed in place instead of needing a relaunch."""
+
+    def _agents(self, *slugs: str) -> list[SimpleNamespace]:
+        return [SimpleNamespace(slug=s) for s in slugs]
+
+    def test_repoints_every_running_bottle(self) -> None:
+        with patch(f"{_MOD}.enumerate_active", return_value=self._agents("a", "b")), \
+                patch(f"{_MOD}.set_gateway_host") as setter:
+            updated = refresh_gateway_host("192.168.128.19")
+        self.assertEqual(["bot-bottle-a", "bot-bottle-b"], updated)
+        self.assertEqual(
+            [("bot-bottle-a", "192.168.128.19"), ("bot-bottle-b", "192.168.128.19")],
+            [c.args for c in setter.call_args_list],
+        )
+
+    def test_one_failing_bottle_does_not_stop_the_sweep(self) -> None:
+        """A container that is already exiting must not block the repair of
+        its neighbours, nor fail the launch that triggered the sweep."""
+        def _flaky(name: str, _ip: str) -> None:
+            if name == "bot-bottle-a":
+                raise RuntimeError("container is exiting")
+
+        with patch(f"{_MOD}.enumerate_active", return_value=self._agents("a", "b")), \
+                patch(f"{_MOD}.set_gateway_host", side_effect=_flaky), \
+                patch(f"{_MOD}.warn") as warn:
+            updated = refresh_gateway_host("10.0.0.1")
+        self.assertEqual(["bot-bottle-b"], updated)
+        warn.assert_called_once()
+
+    def test_no_running_bottles_is_a_clean_no_op(self) -> None:
+        with patch(f"{_MOD}.enumerate_active", return_value=[]), \
+                patch(f"{_MOD}.set_gateway_host") as setter:
+            self.assertEqual([], refresh_gateway_host("10.0.0.1"))
+        setter.assert_not_called()
+
+
+
+class TestLaunchWiring(unittest.TestCase):
+    """Ordering matters: the name must resolve before anything execs, and the
+    stranded-bottle sweep must run once the gateway is known to be up."""
+
+    def test_launch_sets_the_host_entry_before_reading_the_source_ip(self) -> None:
+        """The agent's every URL names the gateway, so the entry has to exist
+        before the first connection — which means before the agent execs."""
+        import inspect
+
+        from bot_bottle.backend.macos_container import launch
+
+        src = inspect.getsource(launch)
+        set_at = src.index("set_gateway_host(plan.container_name")
+        exec_at = src.index("wait_container_ipv4_on_network")
+        self.assertLess(set_at, exec_at)
+
+    def test_launch_refreshes_stranded_bottles_after_ensure_gateway(self) -> None:
+        import inspect
+
+        from bot_bottle.backend.macos_container import launch
+
+        src = inspect.getsource(launch)
+        ensure_at = src.index("endpoint = ensure_gateway()")
+        refresh_at = src.index("refresh_gateway_host(endpoint.gateway_ip)")
+        self.assertLess(ensure_at, refresh_at)
+
+
+if __name__ == "__main__":
+    unittest.main()