fix(orchestrator): address review on host control server transport (#468)

Codex review on #496:

- **High — ambiguous delivery no longer orphans a launched bottle.** A
  timeout / dropped response from the host controller is now the ambiguous
  BrokerUnavailableError (distinct from the definite BrokerAuthError /
  BrokerClientError). OrchestratorCore.launch_bottle keeps the registry
  row on the ambiguous case instead of deregistering — deregistering would
  orphan a running container with no record (reconcile reaps rows, never
  containers). The row is left for reconcile to reap iff the bottle is not
  actually live. Definite failures still roll back, so a real failure
  leaves no orphan row.
- **Medium — the privileged endpoint bounds request bodies.** The host
  server rejects an oversized Content-Length with 413 before reading it,
  and sets a per-request socket timeout, so a caller that can merely reach
  the socket (no signed token) can't exhaust memory or a handler thread.

Tests: ambiguous-keep vs definite-rollback in the launch path; the
BrokerUnavailableError/BrokerClientError split in BrokerClient; the 413
body cap + handler error paths (driven in-thread, since daemon request
threads lose coverage) plus a deterministic real-socket check that
declares an oversized Content-Length but sends a sliver (rejection on the
header, no unread-body reset race); and the __main__ entrypoint broker
selection. Diff-coverage 98%; pyright clean; pylint 9.8.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/orchestrator/__main__.py

@@ -17,7 +17,9 @@ from pathlib import Path
 
 from .. import log
 from .store.store_manager import StoreManager
-from .broker import LaunchBroker, StubBroker
+from .broker import StubBroker, SubmitBroker
+from .broker_client import BrokerClient
+from .host_server import BROKER_SECRET_ENV, DEFAULT_PORT, broker_secret_from_env
 from .server import make_server
 from .docker_broker import DockerBroker
 from .store.registry_store import RegistryStore, default_db_path
@@ -34,8 +36,13 @@ def main(argv: list[str] | None = None) -> int:
         help=f"registry DB path (default: {default_db_path()})",
     )
     parser.add_argument(
-        "--broker", choices=("stub", "docker"), default="stub",
-        help="launch broker: 'stub' records requests; 'docker' runs containers",
+        "--broker", choices=("stub", "docker", "http"), default="stub",
+        help="launch broker: 'stub' records requests; 'docker' runs containers "
+             "in-process; 'http' relays signed requests to a host control server",
+    )
+    parser.add_argument(
+        "--host-controller-url", default=f"http://127.0.0.1:{DEFAULT_PORT}",
+        help="host control server URL (used only with --broker http)",
     )
     args = parser.parse_args(argv)
 
@@ -47,11 +54,25 @@ def main(argv: list[str] | None = None) -> int:
     # operator reaches it over HTTP (never a second, disconnected DB).
     StoreManager(registry.db_path).migrate()
 
-    # An ephemeral signing secret ties the orchestrator (signer) to its
-    # broker (verifier). 'stub' records launches instead of starting
-    # anything; 'docker' runs real containers (firecracker drops in later).
-    secret = secrets.token_bytes(32)
-    broker: LaunchBroker = DockerBroker(secret) if args.broker == "docker" else StubBroker(secret)
+    # A signing secret ties the orchestrator (signer) to its broker (verifier).
+    # 'stub' records launches instead of starting anything; 'docker' runs real
+    # containers in-process; 'http' relays signed requests to a separate host
+    # control server, which verifies and launches. For 'stub'/'docker' the
+    # secret is ephemeral (signer and verifier share this process); for 'http'
+    # it must be the SAME secret the host controller holds, so it is read from
+    # the shared env var (the chunk-1 stand-in for out-of-band provisioning).
+    broker: SubmitBroker
+    if args.broker == "http":
+        secret = broker_secret_from_env()
+        if secret is None:
+            parser.error(
+                f"--broker http requires a shared signing secret in "
+                f"${BROKER_SECRET_ENV} (hex), matching the host control server"
+            )
+        broker = BrokerClient(args.host_controller_url)
+    else:
+        secret = secrets.token_bytes(32)
+        broker = DockerBroker(secret) if args.broker == "docker" else StubBroker(secret)
     orchestrator = OrchestratorCore(registry, broker, secret)
 
     server = make_server(orchestrator, host=args.host, port=args.port)

bot_bottle/orchestrator/broker.py

@@ -29,6 +29,7 @@ import json
 import secrets
 import time
 from dataclasses import dataclass
+from typing import Protocol
 
 _JWT_HEADER = {"alg": "HS256", "typ": "JWT"}
 _ALLOWED_OPS = ("launch", "teardown")
@@ -37,7 +38,21 @@ _ALLOWED_OPS = ("launch", "teardown")
 class BrokerAuthError(Exception):
     """A broker request failed provenance or schema verification —
     bad/absent signature, malformed token, or a payload that doesn't match
-    the fixed launch-request shape. Fail-closed: the broker must not act."""
+    the fixed launch-request shape. Fail-closed: the broker must not act.
+
+    A **definite** negative: nothing was launched, so a caller may safely roll
+    back as if the op never happened."""
+
+
+class BrokerUnavailableError(Exception):
+    """A brokered request could not be carried to a verdict: the broker (or the
+    wire to it) was unreachable, timed out, or dropped the response.
+
+    Crucially **ambiguous** — unlike `BrokerAuthError`, the op MAY already have
+    taken effect on the backend before the response was lost, so a caller must
+    NOT assume it did nothing (e.g. must not roll a registry row back as if no
+    launch happened, which would orphan a running container). Only the in-process
+    brokers never raise this; the out-of-process `BrokerClient` does."""
 
 
 @dataclass(frozen=True)
@@ -123,6 +138,16 @@ def verify_request(token: str, secret: bytes) -> LaunchRequest:
 
 # --- the broker itself ------------------------------------------------------
 
+class SubmitBroker(Protocol):
+    """The single method `OrchestratorCore` depends on: verify a signed token and
+    perform its op, returning the verified request. Both the in-process
+    `LaunchBroker` and the out-of-process `BrokerClient` (which relays the token
+    to the host control server) satisfy it structurally, so the core is unchanged
+    whether the backend is local or a real host service."""
+
+    def submit(self, token: str) -> LaunchRequest: ...
+
+
 class LaunchBroker(abc.ABC):
     """Verifies a signed request came from the orchestrator, then performs
     the backend-native launch/teardown. Subclasses implement `_launch` /
@@ -168,7 +193,9 @@ class StubBroker(LaunchBroker):
 
 __all__ = [
     "BrokerAuthError",
+    "BrokerUnavailableError",
     "LaunchRequest",
+    "SubmitBroker",
     "LaunchBroker",
     "StubBroker",
     "sign_request",

bot_bottle/orchestrator/broker_client.py

@@ -0,0 +1,126 @@
+"""Orchestrator-side broker transport (issue #468, chunk 1).
+
+The signer's half of the launch-broker transport gap. `BrokerClient` satisfies
+the exact `submit(token)` contract `OrchestratorCore` already depends on (see
+`broker.SubmitBroker`), but instead of verifying and launching in-process it POSTs
+the signed token to the host control server over HTTP (stdlib `urllib`, like
+`orchestrator/client.py`). Because it is drop-in for that interface, wiring a real
+out-of-process backend does not change the core: it still signs a request and
+calls `submit()`; only the wire is new.
+
+A provenance/schema rejection from the host controller (HTTP 401) is re-raised as
+the same `BrokerAuthError` the in-process broker raises, so the launch path's
+rollback-on-failure (`OrchestratorCore.launch_bottle`) behaves identically whether
+the broker is local or remote.
+"""
+
+from __future__ import annotations
+
+import json
+import urllib.error
+import urllib.request
+
+from .broker import BrokerAuthError, BrokerUnavailableError, LaunchRequest
+
+DEFAULT_TIMEOUT_SECONDS = 5.0
+
+
+class BrokerClientError(RuntimeError):
+    """The host control server *responded*, but with an unexpected status other
+    than the fail-closed 401 (which surfaces as `BrokerAuthError`) — e.g. a 502
+    backend failure or a malformed body. A definite negative: the host processed
+    the request and it did not launch. (A *no-response* failure — unreachable /
+    timeout / dropped — is the ambiguous `BrokerUnavailableError` instead.)"""
+
+
+class BrokerClient:
+    """Drop-in `submit(token)` that relays a signed request to the host control
+    server. Holds no secret — provenance rides entirely in the signed token, so a
+    caller that can reach this client still cannot forge a launch."""
+
+    def __init__(self, base_url: str, *, timeout: float = DEFAULT_TIMEOUT_SECONDS) -> None:
+        self._base = base_url.rstrip("/")
+        self._timeout = timeout
+
+    def submit(self, token: str) -> LaunchRequest:
+        """POST the signed token to the host controller and return the request it
+        verified and acted on.
+
+        Raises `BrokerAuthError` on a fail-closed 401 (bad provenance/schema —
+        the same exception the in-process broker raises); `BrokerClientError` if
+        the host *responds* with any other non-success status or a malformed
+        body (a definite negative); or `BrokerUnavailableError` if no response is
+        obtained (unreachable / timeout / dropped) — the **ambiguous** case, where
+        the host may already have acted, so the caller must not roll back."""
+        data = json.dumps({"token": token}).encode()
+        req = urllib.request.Request(
+            f"{self._base}/broker", data=data, method="POST",
+            headers={"Content-Type": "application/json"},
+        )
+        try:
+            with urllib.request.urlopen(req, timeout=self._timeout) as resp:
+                return _request_from(_json_object(resp.read()))
+        except urllib.error.HTTPError as e:
+            detail = _error_detail(e)
+            if e.code == 401:
+                raise BrokerAuthError(
+                    detail or "host controller rejected the request"
+                ) from e
+            raise BrokerClientError(
+                f"POST /broker: HTTP {e.code} {detail}".rstrip()
+            ) from e
+        except (urllib.error.URLError, TimeoutError, OSError) as e:
+            # No usable response — unreachable, timed out, or the connection
+            # dropped mid-exchange. Ambiguous: the request may already have
+            # launched the bottle, so this is NOT a definite failure.
+            raise BrokerUnavailableError(f"POST /broker: {e}") from e
+
+
+def _json_object(raw: bytes) -> dict[str, object]:
+    """Parse a JSON object, tolerating an empty or malformed body (→ {}), like
+    the orchestrator client — a bad body becomes a clean 'missing field' error
+    downstream rather than an opaque JSON crash."""
+    if not raw:
+        return {}
+    try:
+        obj = json.loads(raw)
+    except ValueError:
+        return {}
+    return obj if isinstance(obj, dict) else {}
+
+
+def _error_detail(e: urllib.error.HTTPError) -> str:
+    """The `error` string from a structured error response, best-effort — an
+    error body may be absent or unreadable, in which case there is no detail."""
+    try:
+        detail = _json_object(e.read()).get("error", "")
+    except Exception:  # noqa: BLE001 — the error body is advisory only
+        return ""
+    return detail if isinstance(detail, str) else ""
+
+
+def _request_from(payload: dict[str, object]) -> LaunchRequest:
+    """Reconstruct the verified `LaunchRequest` the controller echoed, so the
+    returned value matches the in-process broker's (which returns the request it
+    acted on). A missing op/bottle_id means a malformed response."""
+    op = payload.get("op")
+    bottle_id = payload.get("bottle_id")
+    if not isinstance(op, str) or not isinstance(bottle_id, str) or not bottle_id:
+        raise BrokerClientError("host controller response missing op/bottle_id")
+    source_ip = payload.get("source_ip")
+    image_ref = payload.get("image_ref")
+    slot = payload.get("slot")
+    return LaunchRequest(
+        op=op,
+        bottle_id=bottle_id,
+        source_ip=source_ip if isinstance(source_ip, str) else "",
+        image_ref=image_ref if isinstance(image_ref, str) else "",
+        slot=slot if isinstance(slot, int) and not isinstance(slot, bool) else None,
+    )
+
+
+__all__ = [
+    "BrokerClient",
+    "BrokerClientError",
+    "DEFAULT_TIMEOUT_SECONDS",
+]

bot_bottle/orchestrator/host_server.py

@@ -0,0 +1,270 @@
+"""Host control server (issue #468) — the launch broker as a real host service.
+
+Chunk 1 of the host-control-server stack closes the **transport** gap the PRD
+opens with: today `LaunchBroker.submit(token)` is an in-process method call from
+`OrchestratorCore`, and a real host service needs it reachable over the wire.
+This module is that service — the single privileged host component — reached over
+**HTTP** (the universal transport 0070 chose), mirroring the orchestrator control
+plane's shape (`orchestrator/server.py`): a pure `dispatch()` for socket-free
+testing, wrapped by a thin stdlib `http.server` adapter.
+
+    GET  /health  -> 200 {"status": "ok"}
+    POST /broker  -> 200 {"op", "bottle_id", "source_ip", "image_ref", "slot"}
+                     400 (bad body) | 401 (bad provenance/schema) | 502 (backend)
+                     body: {"token": "<signed launch/teardown JWT>"}
+
+Only the **signed token** crosses the wire; the server holds the shared HS256
+secret and a real `LaunchBroker` (e.g. `DockerBroker`) and runs the existing
+`verify_request` + `_launch`/`_teardown` path behind the endpoint, so nothing
+free-form ever reaches it. Provenance/schema failures are fail-closed 401s that
+never touch the backend (`LaunchBroker.submit` verifies before acting), and a
+backend launch failure is a 502 the caller must surface — neither takes the
+controller down.
+
+The signed launch token *is* the endpoint's authentication (its provenance is the
+whole point of the JWS), so `/broker` needs no separate caller credential; the
+host controller's own lifecycle endpoints, which do, arrive with the durable
+`TrustDomain` key in a later chunk.
+
+The shared signing secret is read from `$BOT_BOTTLE_BROKER_SECRET` (hex). That is
+a **chunk-1 stopgap**: it must be provisioned to signer and verifier out of band,
+which is exactly what the durable `TrustDomain` key in chunk 2 (#476) replaces.
+"""
+
+from __future__ import annotations
+
+import argparse
+import http.server
+import json
+import os
+import socketserver
+import sys
+import typing
+from urllib.parse import urlsplit
+
+from .. import log
+from .broker import BrokerAuthError, LaunchBroker
+from .docker_broker import DockerBroker
+
+# JSON body payload type (parsed request / rendered response).
+Json = dict[str, object]
+
+# The hex-encoded HS256 secret shared with the request signer (the orchestrator).
+# Chunk-1 stopgap for the durable, out-of-band `TrustDomain` key of chunk 2.
+BROKER_SECRET_ENV = "BOT_BOTTLE_BROKER_SECRET"
+
+# Default host-controller port. Distinct from the orchestrator control plane
+# (8099) — a separate privileged component listening on its own socket.
+DEFAULT_PORT = 8091
+
+# Cap on the request body. A signed broker request is tiny, so rejecting anything
+# larger *before reading it* keeps a caller that can merely reach the socket (no
+# signed token needed) from exhausting memory or a handler thread with a huge
+# Content-Length — the signed token, not mere reachability, is the authority.
+MAX_BODY_BYTES = 64 * 1024
+
+# Per-request socket timeout, bounding how long a stalled / slow-loris caller can
+# hold a handler thread on this privileged listener.
+REQUEST_TIMEOUT_SECONDS = 15
+
+
+def _parse_json_object(body: bytes) -> Json:
+    """Parse a JSON object body. Raises ValueError for non-objects / bad JSON."""
+    if not body:
+        return {}
+    obj = json.loads(body)  # raises json.JSONDecodeError (a ValueError)
+    if not isinstance(obj, dict):
+        raise ValueError("request body must be a JSON object")
+    return obj
+
+
+def broker_secret_from_env(environ: typing.Mapping[str, str] | None = None) -> bytes | None:
+    """The shared HS256 secret from `$BOT_BOTTLE_BROKER_SECRET` (hex), or None
+    when unset or not valid hex. The signer (orchestrator, `--broker http`) and
+    the verifier (this server) read the same env var so both hold the same key —
+    the chunk-1 stand-in for out-of-band provisioning."""
+    env = os.environ if environ is None else environ
+    raw = env.get(BROKER_SECRET_ENV, "").strip()
+    if not raw:
+        return None
+    try:
+        return bytes.fromhex(raw)
+    except ValueError:
+        return None
+
+
+def dispatch(  # pylint: disable=too-many-return-statements
+    broker: LaunchBroker, method: str, path: str, body: bytes,
+) -> tuple[int, Json]:
+    """Route one host-control request to a (status, payload) pair. Pure — the
+    only side effect is the broker's own backend launch — so routing is testable
+    without a socket.
+
+    Total by design: a provenance/schema failure becomes 401 and a backend launch
+    failure becomes 502 rather than raising, so one bad request can neither act
+    on the backend nor take the controller down for the next caller."""
+    route = urlsplit(path).path.rstrip("/") or "/"
+
+    if method == "GET" and route == "/health":
+        return 200, {"status": "ok"}
+
+    if method == "POST" and route == "/broker":
+        try:
+            data = _parse_json_object(body)
+        except ValueError as e:
+            return 400, {"error": f"invalid JSON: {e}"}
+        token = data.get("token")
+        if not isinstance(token, str) or not token:
+            return 400, {"error": "token (string) is required"}
+        try:
+            req = broker.submit(token)
+        except BrokerAuthError as e:
+            # Fail-closed: bad signature, malformed token, or off-schema payload.
+            # `submit` verifies before acting, so nothing was launched.
+            return 401, {"error": f"broker auth failed: {e}"}
+        except Exception as e:  # noqa: BLE001 — a backend launch failure (docker
+            # down, image gone) is operational, not a control-plane bug; the
+            # caller must see it as a distinct 502, and the server must stay up.
+            return 502, {"error": f"backend launch failed: {e}"}
+        return 200, {
+            "op": req.op,
+            "bottle_id": req.bottle_id,
+            "source_ip": req.source_ip,
+            "image_ref": req.image_ref,
+            "slot": req.slot,
+        }
+
+    return 404, {"error": "not found"}
+
+
+class Handler(http.server.BaseHTTPRequestHandler):
+    """Thin stdlib adapter: read the body, call `dispatch`, write JSON."""
+
+    # Socket timeout per request (applied by StreamRequestHandler.setup) so a
+    # stalled caller can't pin a handler thread on this privileged listener.
+    timeout = REQUEST_TIMEOUT_SECONDS
+
+    # Quiet by default; opt back into stdlib access logging with
+    # BOT_BOTTLE_HOST_CONTROLLER_DEBUG (the controller has its own logging).
+    def log_message(self, format: str, *args: typing.Any) -> None:  # noqa: A002
+        if os.environ.get("BOT_BOTTLE_HOST_CONTROLLER_DEBUG"):
+            super().log_message(format, *args)
+
+    def _serve(self, method: str) -> None:
+        """Read the request body (bounded), dispatch it, and write the JSON
+        reply. A dispatch that raises (it shouldn't — dispatch is total) still
+        returns a 500 rather than dropping the connection."""
+        server = self.server
+        assert isinstance(server, HostControlServer)
+        try:
+            length = int(self.headers.get("Content-Length") or 0)
+        except ValueError:
+            self._reply(400, {"error": "invalid Content-Length"})
+            return
+        if length < 0 or length > MAX_BODY_BYTES:
+            # Reject before reading: nothing legitimate is this big, so an
+            # oversized declared length is a bug or a resource-exhaustion attempt.
+            self._reply(413, {"error": "request body too large"})
+            return
+        body = self.rfile.read(length) if length > 0 else b""
+        try:
+            status, payload = dispatch(server.broker, method, self.path, body)
+        except Exception as e:  # noqa: BLE001 — the controller must stay up
+            sys.stderr.write(f"host controller: {method} {self.path} failed: {e!r}\n")
+            sys.stderr.flush()
+            status, payload = 500, {"error": f"internal error: {e}"}
+        self._reply(status, payload)
+
+    def _reply(self, status: int, payload: typing.Mapping[str, object]) -> None:
+        """Write one JSON response with an explicit Content-Length."""
+        data = json.dumps(payload).encode()
+        self.send_response(status)
+        self.send_header("Content-Type", "application/json")
+        self.send_header("Content-Length", str(len(data)))
+        self.end_headers()
+        self.wfile.write(data)
+
+    def do_GET(self) -> None:
+        self._serve("GET")
+
+    def do_POST(self) -> None:
+        self._serve("POST")
+
+
+class HostControlServer(socketserver.ThreadingMixIn, http.server.HTTPServer):
+    """Threading HTTP server that carries the launch broker for its handlers.
+
+    The broker holds the shared signing secret and performs the backend-native
+    launch/teardown; the server itself keeps no secret of its own — provenance
+    rides entirely in each request's signed token."""
+
+    daemon_threads = True
+    allow_reuse_address = True
+
+    def __init__(self, address: tuple[str, int], broker: LaunchBroker) -> None:
+        self.broker = broker
+        super().__init__(address, Handler)
+
+
+def make_host_server(
+    broker: LaunchBroker, host: str = "127.0.0.1", port: int = DEFAULT_PORT
+) -> HostControlServer:
+    """Build (but do not start) a host control server. `port=0` binds an
+    ephemeral port — read `server.server_address` for the actual one."""
+    return HostControlServer((host, port), broker)
+
+
+def main(argv: list[str] | None = None) -> int:
+    """Run the host control server as a plain process (dev-harness).
+
+        python -m bot_bottle.orchestrator.host_server [--host H] [--port P]
+
+    Fail-closed: without a shared `$BOT_BOTTLE_BROKER_SECRET` the server can
+    verify no request's provenance, so it refuses to start rather than run a
+    launcher that accepts unsigned input."""
+    parser = argparse.ArgumentParser(prog="bot_bottle.orchestrator.host_server")
+    parser.add_argument("--host", default="127.0.0.1", help="bind address")
+    parser.add_argument("--port", type=int, default=DEFAULT_PORT, help="bind port (0 = ephemeral)")
+    args = parser.parse_args(argv)
+
+    secret = broker_secret_from_env()
+    if secret is None:
+        sys.stderr.write(
+            f"host controller: refusing to start without a shared signing secret "
+            f"(${BROKER_SECRET_ENV}, hex) — it could verify no request's "
+            "provenance and would relay unsigned launches to the backend\n"
+        )
+        sys.stderr.flush()
+        return 2
+
+    broker = DockerBroker(secret)
+    server = make_host_server(broker, host=args.host, port=args.port)
+    bound_host, bound_port = server.server_address[0], server.server_address[1]
+    log.info(
+        "host control server listening",
+        context={"host": bound_host, "port": bound_port},
+    )
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        log.info("host controller shutting down")
+    finally:
+        server.server_close()
+    return 0
+
+
+__all__ = [
+    "dispatch",
+    "Handler",
+    "HostControlServer",
+    "make_host_server",
+    "broker_secret_from_env",
+    "main",
+    "Json",
+    "BROKER_SECRET_ENV",
+    "DEFAULT_PORT",
+]
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

bot_bottle/orchestrator/service.py

@@ -25,7 +25,7 @@ import json
 from collections.abc import Iterable
 from datetime import datetime, timezone
 
-from .broker import LaunchBroker, LaunchRequest, sign_request
+from .broker import BrokerUnavailableError, LaunchRequest, SubmitBroker, sign_request
 from .store.registry_store import DEFAULT_REAP_GRACE_SECONDS, BottleRecord, RegistryStore
 from .supervisor import (
     AuditEntry,
@@ -62,7 +62,7 @@ class OrchestratorCore:
     def __init__(
         self,
         registry: RegistryStore,
-        broker: LaunchBroker,
+        broker: SubmitBroker,
         sign_secret: bytes,
         supervisor: Supervisor | None = None,
     ) -> None:
@@ -111,14 +111,23 @@ class OrchestratorCore:
             image_ref=image_ref,
             slot=slot,
         )
-        launched = False
         try:
             self._broker.submit(sign_request(req, self._secret))
-            launched = True
-        finally:
-            if not launched:
-                self.registry.deregister(rec.bottle_id)
-                self._tokens.pop(rec.bottle_id, None)
+        except BrokerUnavailableError:
+            # Ambiguous delivery failure (timeout / dropped response): the broker
+            # may already have launched the bottle before the response was lost.
+            # Do NOT deregister — that would orphan a running container with no
+            # registry row (reconcile reaps rows, never containers). Keep the row
+            # so reconcile reaps it iff the bottle is not actually live; surface
+            # the error so the caller knows the launch is unconfirmed.
+            raise
+        except Exception:
+            # A definite failure — a fail-closed rejection, a backend launch
+            # error, or the host reporting it did not launch: nothing is running,
+            # so roll the registry entry back to leave no orphan.
+            self.registry.deregister(rec.bottle_id)
+            self._tokens.pop(rec.bottle_id, None)
+            raise
         return rec
 
     def teardown_bottle(self, bottle_id: str) -> bool:

docs/prds/prd-new-host-control-server.md

@@ -0,0 +1,273 @@
+# PRD prd-new: Host control server
+
+- **Status:** Draft
+- **Author:** Claude
+- **Created:** 2026-07-26
+- **Issue:** #468
+
+## Summary
+
+Promote the in-process launch broker into a standalone **host control
+server**: the single privileged component on the host. Both the CLI and the
+orchestrator drive it over HTTP; it brokers agent launches, owns the
+orchestrator's own lifecycle, and is the sole writer of host-durable state (the
+tamper-evident audit record). This closes the three gaps between today's
+well-formed broker *contract* ([`orchestrator/broker.py`](../../bot_bottle/orchestrator/broker.py))
+and a real out-of-process service — transport, durable provisioned secret,
+and a disciplined op vocabulary — and splits host state by
+owner and lifetime. The prize: **the CLI no longer needs the Docker socket**,
+which is what finally lets a dedicated Gitea runner user drop the
+root-equivalent `docker` group (PRD 0070, "Relationship to other work").
+
+## Problem
+
+Container launches run directly from a short-lived CLI process against the
+Docker socket. That socket is root-equivalent, so every host that launches
+bottles hands root to whoever invokes the CLI — including a CI runner user we
+want to keep unprivileged. PRD 0070 already argues for replacing the fat socket
+with a **thin, structured, auditable** launch broker, and the contract for that
+broker exists and is tested in-process. But it is *only* in-process:
+`LaunchBroker.submit(token)` is a method call from
+`OrchestratorCore.launch_bottle` ([`service.py:116`](../../bot_bottle/orchestrator/service.py)),
+and `DockerBroker` is on no production path — every backend starts the
+orchestrator with `--broker stub` ([`__main__.py:54`](../../bot_bottle/orchestrator/__main__.py)).
+
+Three gaps stand between that scaffold and a host service:
+
+1. **No transport.** `submit` is an in-process call. A real service needs a
+   `BrokerClient` that POSTs the signed token and a host-side HTTP server that
+   verifies and acts.
+2. **The signing secret is ephemeral and self-generated.**
+   [`__main__.py:53`](../../bot_bottle/orchestrator/__main__.py) does
+   `secrets.token_bytes(32)` and hands the *same value* to signer and verifier —
+   viable only because they share a process. A separate daemon needs the secret
+   provisioned out of band and durable across orchestrator restarts.
+3. **The op vocabulary is `launch` / `teardown` only.** Everything else
+   host-privileged still lives in the CLI, so the schema has to grow — carefully,
+   since PRD 0070's security argument rests on "structured requests only, static
+   flags + ids."
+
+Separately, host state has no clear owner. `OrchestratorCore.reconcile` takes
+`live_source_ips` as a parameter *only because the orchestrator cannot see the
+backend* ([`service.py:137`](../../bot_bottle/orchestrator/service.py)); the
+egress traffic log is written to the container's stderr; and there is no durable,
+tamper-evident home for the audit record that survives orchestrator destruction.
+
+## Goals / Success Criteria
+
+- A standalone host control server that the CLI and orchestrator reach over
+  **HTTP**, with three entry paths working end to end:
+  - `web console -(iroh)-> orchestrator -(http)-> host controller -> launch`
+  - `cli -(http)-> orchestrator -(http)-> host controller -> launch`
+  - `cli -(http)-> host controller` — start / restart / status of the
+    orchestrator **itself** (the bootstrap/recovery path #391 targets).
+- The launch op is expressed as a **signed JWT of static flags + ids only**,
+  verified against a closed schema.
+- The signing secret is **provisioned out of band and durable** across
+  orchestrator restarts (a `TrustDomain` per #476, with a key the orchestrator
+  never holds for the host controller's *own* endpoints).
+- Host-privileged operations move off the CLI to the control server; **the CLI
+  no longer opens the Docker socket** for bottle operations.
+- `Orchestrator.reconcile` no longer takes `live_source_ips` — live-bottle
+  enumeration becomes an internal control-server call.
+- Host-durable state lands as an **append-only, hash-chained JSONL** audit log
+  owned solely by the host controller; operational state stays SQLite owned
+  solely by the orchestrator.
+
+## Non-goals
+
+- **Removing standing privilege.** This converts on-demand privilege (a CLI the
+  user invokes) into standing privilege (a daemon under launchd/systemd). The
+  win is that the privilege is *narrower* (structured requests vs. a raw socket),
+  not that it disappears. "Always running" is an accepted new property.
+- **Asymmetric signing.** We stay HS256 — see Design / "Signing stays
+  symmetric."
+- **Integrity against a live compromised orchestrator.** Host-location of the
+  audit log does not buy this: the orchestrator makes the decisions being audited
+  and can forge or omit entries wherever the file lives. An off-box copy is the
+  answer, tracked separately.
+- **A single unified DB for all state.** Impossible over a guest-kernel share
+  (SQLite locking is not coherent); state is split by owner and lifetime instead.
+- **The generic `SecretProvider` (#355)** and **remote terminal design (#478)** —
+  both ride the same door but are their own work.
+
+## Design
+
+### Topology
+
+The host controller is the sole privileged component. The orchestrator becomes a
+client of it for launches, and the CLI becomes a client of it for *both* bottle
+operations (indirectly, through the orchestrator) and orchestrator lifecycle
+(directly, for bootstrap/recovery — startup can't route through the thing being
+started).
+
+```
+web console ─(iroh)─▶ orchestrator ─┐
+                                    ├─(http, signed JWT)─▶ host controller ─▶ launch
+cli ────────(http)──▶ orchestrator ─┘
+cli ────────(http, bearer)──────────────────────────────▶ host controller   (orchestrator lifecycle)
+```
+
+### Transport: `BrokerClient` + host server
+
+`LaunchBroker.submit(token)` keeps its exact signature and semantics; only the
+*wire* changes. A new `BrokerClient` implements the same submit contract by
+POSTing the signed token to the host controller (stdlib `urllib`, like the
+existing [`orchestrator/client.py`](../../bot_bottle/orchestrator/client.py)),
+and the host controller's launch handler is the existing `verify_request` +
+`_launch`/`_teardown` path, now reached over HTTP instead of a method call. The
+in-process `StubBroker` stays for the dev-harness and tests; `DockerBroker`'s
+`_launch`/`_teardown` bodies move behind the server unchanged. Because the client
+satisfies the same interface `OrchestratorCore` already depends on, the core does
+not change to gain a real backend.
+
+### Signing stays symmetric (HS256)
+
+PRD 0070 nominally specifies asymmetric; the code is HS256 and we keep it.
+Asymmetric matters when the verifier is *less* privileged than the signer — here
+it is the reverse: the host controller (verifier) is strictly more privileged
+than the orchestrator (signer), and a controller that could forge orchestrator
+requests gains nothing, since it is already the component that launches. Staying
+symmetric also honors the no-runtime-deps policy (stdlib has no Ed25519). This
+matches the reasoning already inlined in `broker.py`'s module docstring.
+
+### Replay protection is out of scope (tracked in #494)
+
+Once the launch token travels over a wire, a captured token could be replayed —
+`sign_request` already emits `jti`/`iat` but `verify_request` reads neither, so
+there is no expiry window or `jti` cache today. Enforcing that (an `iat` window +
+a self-trimming `jti` cache) is a pure in-process change that lands independently
+of this work, and it is deferred to **#494** rather than gating the MVP of the
+host control server. Nothing here depends on it; it can merge before or after.
+
+### Op vocabulary and the "ids + static flags" rule (gap 3)
+
+Each op moved off the CLI widens the privileged surface, so growth is governed by
+one explicit rule, enforced in `verify_request`'s schema check:
+
+> A broker op carries **only ids and enumerated static flags** — a bottle id, a
+> pool slot, a **content-addressed** image ref chosen from a fixed set, an op
+> name from a closed vocabulary. Never a free-form path, argv, command, or
+> caller-supplied filesystem location. If an operation cannot be expressed that
+> way, it does not become a broker op.
+
+Operations that fit and move off the CLI (all today in
+`backend/*/consolidated_launch.py`, driven by a short-lived CLI process):
+
+| Op | What it does | Fits the rule because |
+|---|---|---|
+| `launch` / `teardown` | existing | ids + slot + image ref |
+| `orchestrator.ensure_running` | start the infra container | no arguments |
+| `orchestrator.{start,restart,status}` | lifecycle (the #391 path) | no arguments |
+| `list_live` | enumerate running bottles for reconcile | no arguments; returns ids/IPs |
+| `allocate_ip` | `next_free_ip` over `_network_container_ips` | no arguments; returns an IP |
+| `provision_git_gate` | `cp`/`exec` a per-bottle deploy key into the gateway | bottle id + key handle, no path |
+| `reprovision` | `docker exec printenv <ENV_VAR_SECRET>` on a live agent | bottle id + secret *name* |
+
+Image **builds** stay with the orchestrator for v1 (PRD 0070 §Memory: builds run
+control-plane-side; a dedicated slim build unit is later, #468-adjacent), so no
+`build` broker op is added here.
+
+With `list_live` as an internal control-server call, `Orchestrator.reconcile`'s
+`live_source_ips` parameter goes away — the tell PRD 0070 called out that the
+orchestrator couldn't see the backend disappears with it.
+
+### Secret provisioning (gap 2)
+
+The shared HS256 secret becomes a durable, out-of-band artifact via the
+**`TrustDomain`** seam (#476,
+[`trust_domain.py`](../../bot_bottle/trust_domain.py)):
+
+- The **launch-broker secret** is a `TrustDomain` whose key
+  (`host_signing_key(<file>)`, minted 0600 on first use, durable under
+  `bot_bottle_root()`) is provisioned to the orchestrator (signer) and the host
+  controller (verifier). Durability across orchestrator restarts is what makes
+  re-adoption work — a restart re-verifies against the same key.
+- The **host controller's own lifecycle endpoints** (the direct `cli -> host
+  controller` path) get a **separate** `TrustDomain` key the orchestrator never
+  holds — exactly the second domain #476's PRD reserves. The orchestrator must
+  not be able to mint the credentials used to start and stop it.
+
+This reuses the seam #476 landed rather than re-deriving provisioning per
+backend (the PR #471 bug class).
+
+### One daemon, structurally separate handlers (open decision 1)
+
+The audit writer and the broker live in **one daemon** for install simplicity,
+but with **no shared parsing** and **different credentials per handler**:
+
+- the **launch** handler requires the signed launch **JWT** (provenance +
+  un-coercible schema);
+- the **audit-append** handler takes a plain **bearer token** and writes to the
+  JSONL log.
+
+This does not defend against orchestrator compromise (it holds both creds) — it
+stops a bug in the boring audit path from reaching the privileged launch path.
+The launcher stays small enough to audit line-by-line, per PRD 0070.
+
+### State ownership: split by owner and lifetime
+
+A single mounted DB is impossible — SQLite locking is not coherent across guest
+kernels over a share, which is why the macOS backend already uses a container-only
+volume (`INFRA_DB_VOLUME`). So state splits three ways (depends on #469, which
+gets `bot-bottle.db` off the data plane first):
+
+| Owner | State | Home | Shape |
+|---|---|---|---|
+| **Orchestrator** | `orchestrator_bottles` registry; `bottled_agent_secrets` (encrypted egress tokens); `supervise_proposals` / `supervise_responses` | volume nothing else mounts (generalizing the macOS design) | **SQLite** — mutable, transactional, queried |
+| **Host controller** | supervise audit entries; egress traffic log (today → container stderr); host-side config | host filesystem, survives orchestrator/volume destruction | **JSONL** — append-only |
+| **Gateway** | none | — | after #469 the data plane holds no DB state |
+
+The historical record is **JSONL, not SQLite**, because it is append-only, never
+updated, never transactionally queried: `O_APPEND` writes are atomic, there is no
+locking protocol to get wrong, hash-chaining for tamper-evidence is cheap, and it
+survives container-runtime volume pruning (the #450 lesson) and stays readable
+without the orchestrator running. Both halves of "the audit record" — supervise
+decisions and the egress traffic log — land in the one place.
+
+The orchestrator is **sole mounter and sole writer** of its SQLite volume; the
+host controller is **sole writer** of the JSONL log, over the authenticated
+audit-append channel.
+
+## Implementation chunks
+
+Ordered, each independently mergeable:
+
+1. **`BrokerClient` + host launch server** over HTTP, reusing `verify_request`
+   and the existing `DockerBroker` bodies. Wire `OrchestratorCore` to a
+   `BrokerClient` behind a flag; keep `StubBroker` for the dev-harness. Closes
+   gap 1.
+2. **Durable secret via `TrustDomain`** — provision the launch-broker key to
+   signer + verifier; add the host controller's own lifecycle `TrustDomain`.
+   Closes gap 2.
+3. **Grow the op vocabulary** one op at a time (`list_live` first — it also
+   removes `reconcile`'s `live_source_ips`), each behind the ids + static-flags
+   rule. Closes gap 3.
+4. **JSONL audit log** — the host-controller-owned, hash-chained historical
+   record with the plain-bearer audit-append handler; redirect the egress traffic
+   log into it.
+5. **Drop the Docker socket from the CLI** once every host-privileged op it used
+   is a broker op — the payoff that unblocks the unprivileged Gitea runner user.
+
+## Open questions
+
+1. **Schema-width rule enforcement.** The "ids + static flags" rule is stated;
+   should `verify_request` reject unknown claim keys outright (strict schema) to
+   keep the surface from drifting? Leaning yes.
+2. **Audit-append back-pressure.** What the audit handler does if the JSONL sink
+   is unavailable (fail-closed vs. buffer) — resolve before shipping chunk 5.
+
+## References
+
+- **PRD 0070** — the contract, the launch broker, and the state tiers this
+  implements.
+- **#469** — get `bot-bottle.db` off the data plane (lands underneath this).
+- **#476** ([`prd-new-control-plane-auth-provisioning`](prd-new-control-plane-auth-provisioning.md))
+  — the `TrustDomain` seam this plugs the host controller's key into.
+- **#391** — backend-agnostic orchestrator restart (the bootstrap path).
+- **#494** — enforce broker replay protection (`iat` window + `jti` cache); split
+  out of this PRD as an independent in-process change.
+- **#386** — prebuilt images from the Gitea OCI registry (the fixed image set the
+  broker validates against).
+- **#355** — generic `SecretProvider`.
+- **#478** — remote terminal design.

tests/unit/test_orchestrator_broker_client.py

@@ -0,0 +1,117 @@
+"""Unit: orchestrator-side broker client (issue #468, chunk 1). HTTP mocked."""
+
+from __future__ import annotations
+
+import io
+import json
+import unittest
+import urllib.error
+from unittest.mock import MagicMock, patch
+
+from bot_bottle.orchestrator.broker import (
+    BrokerAuthError,
+    BrokerUnavailableError,
+    LaunchRequest,
+)
+from bot_bottle.orchestrator.broker_client import BrokerClient, BrokerClientError
+
+_URLOPEN = "bot_bottle.orchestrator.broker_client.urllib.request.urlopen"
+
+
+def _resp(payload: object) -> MagicMock:
+    m = MagicMock()
+    m.__enter__.return_value.read.return_value = json.dumps(payload).encode()
+    return m
+
+
+def _http_error(code: int, payload: object = None) -> urllib.error.HTTPError:
+    body = json.dumps(payload).encode() if payload is not None else b""
+    return urllib.error.HTTPError(
+        "http://host/broker", code, "err", {}, io.BytesIO(body))  # type: ignore[arg-type]
+
+
+class TestSubmit(unittest.TestCase):
+    def setUp(self) -> None:
+        self.c = BrokerClient("http://host:8091")
+
+    def test_returns_the_verified_request(self) -> None:
+        echo = {
+            "op": "launch", "bottle_id": "b1", "source_ip": "10.0.0.1",
+            "image_ref": "img", "slot": 3,
+        }
+        with patch(_URLOPEN, return_value=_resp(echo)):
+            got = self.c.submit("tok")
+        self.assertEqual(
+            LaunchRequest(op="launch", bottle_id="b1", source_ip="10.0.0.1",
+                          image_ref="img", slot=3),
+            got,
+        )
+
+    def test_posts_token_to_broker_endpoint(self) -> None:
+        with patch(_URLOPEN, return_value=_resp({"op": "teardown", "bottle_id": "b1"})) as m:
+            self.c.submit("signed-token")
+        request = m.call_args.args[0]
+        self.assertEqual("POST", request.get_method())
+        self.assertTrue(request.full_url.endswith("/broker"))
+        self.assertEqual({"token": "signed-token"}, json.loads(request.data))
+
+    def test_401_raises_broker_auth_error(self) -> None:
+        # A fail-closed provenance/schema rejection surfaces as the SAME exception
+        # the in-process broker raises, so the launch path's rollback is identical.
+        with patch(_URLOPEN, side_effect=_http_error(401, {"error": "bad signature"})):
+            with self.assertRaises(BrokerAuthError):
+                self.c.submit("forged")
+
+    def test_502_is_a_definite_client_error(self) -> None:
+        # The host responded — it processed the request and did not launch, so a
+        # definite BrokerClientError (the caller may safely roll back).
+        with patch(_URLOPEN, side_effect=_http_error(502, {"error": "docker down"})):
+            with self.assertRaises(BrokerClientError):
+                self.c.submit("tok")
+
+    def test_unreachable_is_ambiguous_unavailable(self) -> None:
+        # No response at all — the request may already have launched, so the
+        # AMBIGUOUS BrokerUnavailableError (the caller must NOT roll back).
+        with patch(_URLOPEN, side_effect=urllib.error.URLError("refused")):
+            with self.assertRaises(BrokerUnavailableError):
+                self.c.submit("tok")
+
+    def test_timeout_is_ambiguous_unavailable(self) -> None:
+        # A dropped/late response after the request was sent is the exact orphan
+        # risk: the host may have launched. Must be ambiguous, not a definite fail.
+        with patch(_URLOPEN, side_effect=TimeoutError("read timed out")):
+            with self.assertRaises(BrokerUnavailableError):
+                self.c.submit("tok")
+
+    def test_malformed_success_body_raises(self) -> None:
+        with patch(_URLOPEN, return_value=_resp({"op": "launch"})):  # missing bottle_id
+            with self.assertRaises(BrokerClientError):
+                self.c.submit("tok")
+
+    def test_empty_error_body_is_tolerated(self) -> None:
+        # An error with no readable JSON body still classifies by status code.
+        with patch(_URLOPEN, side_effect=_http_error(401)):
+            with self.assertRaises(BrokerAuthError):
+                self.c.submit("forged")
+
+    def test_non_json_success_body_raises(self) -> None:
+        # A 200 whose body isn't JSON is tolerated into {} then fails the
+        # missing-field check — a definite client error, not a crash.
+        m = MagicMock()
+        m.__enter__.return_value.read.return_value = b"not json at all"
+        with patch(_URLOPEN, return_value=m):
+            with self.assertRaises(BrokerClientError):
+                self.c.submit("tok")
+
+    def test_unreadable_error_body_is_tolerated(self) -> None:
+        # An HTTPError whose body can't be read (fp=None) still classifies by
+        # status — the error detail is best-effort.
+        err = urllib.error.HTTPError(
+            "http://host/broker", 502, "err", {}, None)  # type: ignore[arg-type]
+        with patch(_URLOPEN, side_effect=err):
+            with self.assertRaises(BrokerClientError):
+                self.c.submit("tok")
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/unit/test_orchestrator_host_server.py

@@ -0,0 +1,285 @@
+"""Unit tests for the host control server (issue #468, chunk 1).
+
+Mostly exercises the pure `dispatch()` (socket-free, like the orchestrator
+server tests), plus a real-socket round-trip through `BrokerClient` that proves
+the full sign -> POST -> verify -> act seam over HTTP.
+"""
+
+from __future__ import annotations
+
+import http.client
+import io
+import json
+import secrets
+import threading
+import typing
+import unittest
+from unittest.mock import MagicMock, patch
+
+from bot_bottle.orchestrator.broker import (
+    BrokerAuthError,
+    LaunchBroker,
+    LaunchRequest,
+    StubBroker,
+    sign_request,
+)
+from bot_bottle.orchestrator.broker_client import BrokerClient
+from bot_bottle.orchestrator.host_server import (
+    MAX_BODY_BYTES,
+    Handler,
+    HostControlServer,
+    broker_secret_from_env,
+    dispatch,
+    main,
+    make_host_server,
+)
+
+
+def _body(obj: object) -> bytes:
+    return json.dumps(obj).encode()
+
+
+class _RaisingBroker(LaunchBroker):
+    """A broker whose backend launch always fails — exercises the 502 path (an
+    operational backend failure, distinct from a fail-closed provenance 401)."""
+
+    def _launch(self, req: LaunchRequest) -> None:
+        raise RuntimeError("docker down")
+
+    def _teardown(self, req: LaunchRequest) -> None:
+        raise RuntimeError("docker down")
+
+
+class TestDispatch(unittest.TestCase):
+    def setUp(self) -> None:
+        self.secret = secrets.token_bytes(16)
+        self.broker = StubBroker(self.secret)
+
+    def _token(self, **kwargs: object) -> str:
+        return sign_request(LaunchRequest(**kwargs), self.secret)  # type: ignore[arg-type]
+
+    def test_health(self) -> None:
+        status, payload = dispatch(self.broker, "GET", "/health", b"")
+        self.assertEqual(200, status)
+        self.assertEqual("ok", payload["status"])
+
+    def test_broker_launch_verifies_and_acts(self) -> None:
+        token = self._token(
+            op="launch", bottle_id="b1", source_ip="10.243.0.1",
+            image_ref="img", slot=2,
+        )
+        status, payload = dispatch(self.broker, "POST", "/broker", _body({"token": token}))
+        self.assertEqual(200, status)
+        self.assertEqual("launch", payload["op"])
+        self.assertEqual("b1", payload["bottle_id"])
+        self.assertEqual("img", payload["image_ref"])
+        self.assertEqual(2, payload["slot"])
+        self.assertEqual(["b1"], [r.bottle_id for r in self.broker.launched])
+
+    def test_broker_teardown_acts(self) -> None:
+        token = self._token(op="teardown", bottle_id="b1")
+        status, _ = dispatch(self.broker, "POST", "/broker", _body({"token": token}))
+        self.assertEqual(200, status)
+        self.assertEqual(["b1"], [r.bottle_id for r in self.broker.torn_down])
+
+    def test_forged_token_is_401_and_nothing_acted(self) -> None:
+        forged = sign_request(
+            LaunchRequest(op="launch", bottle_id="b1"), secrets.token_bytes(16))
+        status, payload = dispatch(self.broker, "POST", "/broker", _body({"token": forged}))
+        self.assertEqual(401, status)
+        self.assertIn("broker auth failed", str(payload["error"]))
+        self.assertEqual([], self.broker.launched)  # fail-closed: never launched
+
+    def test_backend_failure_is_502(self) -> None:
+        broker = _RaisingBroker(self.secret)
+        token = self._token(op="launch", bottle_id="b1", image_ref="img")
+        status, payload = dispatch(broker, "POST", "/broker", _body({"token": token}))
+        self.assertEqual(502, status)
+        self.assertIn("backend launch failed", str(payload["error"]))
+
+    def test_missing_token_is_400(self) -> None:
+        status, _ = dispatch(self.broker, "POST", "/broker", _body({}))
+        self.assertEqual(400, status)
+
+    def test_bad_json_is_400(self) -> None:
+        status, _ = dispatch(self.broker, "POST", "/broker", b"{not json")
+        self.assertEqual(400, status)
+
+    def test_empty_body_is_missing_token_400(self) -> None:
+        # Empty body parses to {} (no token) → 400, never reaching the broker.
+        status, _ = dispatch(self.broker, "POST", "/broker", b"")
+        self.assertEqual(400, status)
+        self.assertEqual([], self.broker.launched)
+
+    def test_non_object_body_is_400(self) -> None:
+        status, _ = dispatch(self.broker, "POST", "/broker", b"[1, 2]")
+        self.assertEqual(400, status)
+
+    def test_unknown_route_404(self) -> None:
+        status, _ = dispatch(self.broker, "GET", "/nope", b"")
+        self.assertEqual(404, status)
+
+    def test_trailing_slash_normalized(self) -> None:
+        status, _ = dispatch(self.broker, "GET", "/health/", b"")
+        self.assertEqual(200, status)
+
+
+class TestBrokerSecretFromEnv(unittest.TestCase):
+    def test_reads_hex_secret(self) -> None:
+        s = secrets.token_bytes(16)
+        self.assertEqual(s, broker_secret_from_env({"BOT_BOTTLE_BROKER_SECRET": s.hex()}))
+
+    def test_unset_is_none(self) -> None:
+        self.assertIsNone(broker_secret_from_env({}))
+
+    def test_invalid_hex_is_none(self) -> None:
+        self.assertIsNone(broker_secret_from_env({"BOT_BOTTLE_BROKER_SECRET": "not-hex"}))
+
+
+class TestSeamRoundTrip(unittest.TestCase):
+    """The whole point of chunk 1: a request signed by the orchestrator side is
+    POSTed to a real host control server, verified there, and acted on — over
+    HTTP, not an in-process call."""
+
+    def _serve(self, broker: LaunchBroker) -> BrokerClient:
+        server = make_host_server(broker, "127.0.0.1", 0)
+        self.addCleanup(server.server_close)
+        threading.Thread(target=server.serve_forever, daemon=True).start()
+        self.addCleanup(server.shutdown)
+        host, port = server.server_address[0], server.server_address[1]
+        return BrokerClient(f"http://{host}:{port}")
+
+    def test_sign_post_verify_act_over_http(self) -> None:
+        secret = secrets.token_bytes(16)
+        broker = StubBroker(secret)
+        client = self._serve(broker)
+        req = LaunchRequest(
+            op="launch", bottle_id="b1", source_ip="10.0.0.1", image_ref="img", slot=1)
+        got = client.submit(sign_request(req, secret))
+        self.assertEqual(req, got)  # the controller echoes the verified request
+        self.assertEqual(["b1"], [r.bottle_id for r in broker.launched])
+
+    def test_forged_token_raises_broker_auth_error_over_http(self) -> None:
+        secret = secrets.token_bytes(16)
+        broker = StubBroker(secret)
+        client = self._serve(broker)
+        forged = sign_request(
+            LaunchRequest(op="launch", bottle_id="b1"), secrets.token_bytes(16))
+        with self.assertRaises(BrokerAuthError):
+            client.submit(forged)
+        self.assertEqual([], broker.launched)  # fail-closed across the wire
+
+
+class TestRequestLimits(unittest.TestCase):
+    """The privileged listener must not let a caller that can merely reach the
+    socket (no signed token) exhaust it via an oversized declared body — and it
+    rejects on the Content-Length *header*, before reading the body."""
+
+    def _addr(self) -> tuple[str, int]:
+        self.broker = StubBroker(secrets.token_bytes(16))
+        server = make_host_server(self.broker, "127.0.0.1", 0)
+        self.addCleanup(server.server_close)
+        threading.Thread(target=server.serve_forever, daemon=True).start()
+        self.addCleanup(server.shutdown)
+        host, port = server.server_address[:2]
+        return typing.cast(str, host), port
+
+    def test_oversized_content_length_is_rejected_before_reading(self) -> None:
+        host, port = self._addr()
+        conn = http.client.HTTPConnection(host, port, timeout=5)
+        self.addCleanup(conn.close)
+        # Declare an oversized body but send only a sliver: the server must reject
+        # on the header before reading, so the caller gets a clean, deterministic
+        # 413 (no large unread body to race a connection reset).
+        conn.putrequest("POST", "/broker", skip_accept_encoding=True)
+        conn.putheader("Content-Type", "application/json")
+        conn.putheader("Content-Length", str(MAX_BODY_BYTES + 1))
+        conn.endheaders()
+        conn.send(b"{}")  # far short of the declared length; never read
+        resp = conn.getresponse()
+        self.assertEqual(413, resp.status)
+        self.assertEqual([], self.broker.launched)  # never reached the broker
+
+
+class TestServeUnit(unittest.TestCase):
+    """Drive `Handler._serve` directly (no socket). The real per-request handler
+    runs in a daemon thread whose coverage/trace data is lost, so the
+    bounded-body and error paths are exercised here in the main thread instead."""
+
+    def _handler(self, broker: LaunchBroker, headers: dict[str, str],
+                 body: bytes = b"") -> tuple[Handler, MagicMock]:
+        server = HostControlServer.__new__(HostControlServer)
+        server.broker = broker
+        h = Handler.__new__(Handler)
+        h.server = server
+        h.headers = headers  # type: ignore[assignment] — dict is a valid .get() stand-in
+        h.path = "/broker"
+        h.rfile = io.BytesIO(body)
+        h.wfile = io.BytesIO()
+        send_response = MagicMock()
+        h.send_response = send_response  # type: ignore[method-assign]
+        h.send_header = MagicMock()  # type: ignore[method-assign]
+        h.end_headers = MagicMock()  # type: ignore[method-assign]
+        return h, send_response
+
+    def test_oversized_content_length_is_413(self) -> None:
+        broker = StubBroker(secrets.token_bytes(16))
+        h, send_response = self._handler(broker, {"Content-Length": str(MAX_BODY_BYTES + 1)})
+        h.do_POST()  # exercises do_POST -> _serve
+        send_response.assert_called_once_with(413)
+        self.assertEqual([], broker.launched)  # rejected before the broker
+
+    def test_invalid_content_length_is_400(self) -> None:
+        h, send_response = self._handler(StubBroker(secrets.token_bytes(16)),
+                                         {"Content-Length": "not-a-number"})
+        h._serve("POST")
+        send_response.assert_called_once_with(400)
+
+    def test_valid_request_dispatches_200(self) -> None:
+        secret = secrets.token_bytes(16)
+        broker = StubBroker(secret)
+        body = _body({"token": sign_request(
+            LaunchRequest(op="teardown", bottle_id="b1"), secret)})
+        h, send_response = self._handler(broker, {"Content-Length": str(len(body))}, body)
+        h._serve("POST")
+        send_response.assert_called_once_with(200)
+        self.assertEqual(["b1"], [r.bottle_id for r in broker.torn_down])
+
+    def test_dispatch_exception_becomes_500(self) -> None:
+        # dispatch is total, but the handler still guards it: a raised dispatch
+        # returns 500 rather than dropping the connection.
+        h, send_response = self._handler(
+            StubBroker(secrets.token_bytes(16)), {"Content-Length": "0"})
+        with patch("bot_bottle.orchestrator.host_server.dispatch",
+                   side_effect=RuntimeError("boom")):
+            h._serve("POST")
+        send_response.assert_called_once_with(500)
+
+    def test_health_over_do_get(self) -> None:
+        h, send_response = self._handler(StubBroker(secrets.token_bytes(16)), {})
+        h.path = "/health"
+        h.do_GET()
+        send_response.assert_called_once_with(200)
+
+
+class TestMain(unittest.TestCase):
+    def test_fail_closed_without_secret(self) -> None:
+        with patch("bot_bottle.orchestrator.host_server.broker_secret_from_env",
+                   return_value=None):
+            self.assertEqual(2, main(["--port", "0"]))
+
+    def test_serves_then_shuts_down_cleanly(self) -> None:
+        fake = MagicMock()
+        fake.server_address = ("127.0.0.1", 0)
+        fake.serve_forever.side_effect = KeyboardInterrupt
+        with patch("bot_bottle.orchestrator.host_server.broker_secret_from_env",
+                   return_value=b"k"), \
+             patch("bot_bottle.orchestrator.host_server.make_host_server",
+                   return_value=fake):
+            self.assertEqual(0, main(["--port", "0"]))
+        fake.serve_forever.assert_called_once()
+        fake.server_close.assert_called_once()
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/unit/test_orchestrator_main.py

@@ -0,0 +1,64 @@
+"""Unit: the orchestrator dev-harness entrypoint (`python -m bot_bottle.orchestrator`).
+
+Exercises broker selection (stub / docker / http) and the fail-closed http path,
+patching `make_server` so the serve loop returns instead of blocking.
+"""
+
+from __future__ import annotations
+
+import os
+import secrets
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from bot_bottle.orchestrator.__main__ import main
+
+
+def _fake_server() -> MagicMock:
+    fake = MagicMock()
+    fake.server_address = ("127.0.0.1", 0)
+    # Break out of serve_forever immediately, exercising the try/finally.
+    fake.serve_forever.side_effect = KeyboardInterrupt
+    return fake
+
+
+class TestMain(unittest.TestCase):
+    def _run(self, broker: str, env: dict[str, str] | None = None) -> tuple[int, MagicMock]:
+        fake = _fake_server()
+        with tempfile.TemporaryDirectory() as d:
+            argv = ["--db", str(Path(d) / "r.db"), "--port", "0", "--broker", broker]
+            with patch("bot_bottle.orchestrator.__main__.make_server", return_value=fake), \
+                    patch.dict("os.environ", env or {}, clear=False):
+                if env is None:
+                    os.environ.pop("BOT_BOTTLE_BROKER_SECRET", None)
+                rc = main(argv)
+        return rc, fake
+
+    def test_stub_broker_serves_and_closes(self) -> None:
+        rc, fake = self._run("stub")
+        self.assertEqual(0, rc)
+        fake.serve_forever.assert_called_once()
+        fake.server_close.assert_called_once()
+
+    def test_docker_broker_serves(self) -> None:
+        rc, _ = self._run("docker")
+        self.assertEqual(0, rc)
+
+    def test_http_broker_with_secret_serves(self) -> None:
+        rc, _ = self._run(
+            "http", env={"BOT_BOTTLE_BROKER_SECRET": secrets.token_bytes(16).hex()})
+        self.assertEqual(0, rc)
+
+    def test_http_broker_without_secret_exits(self) -> None:
+        # Fail-closed: --broker http with no shared secret is a usage error.
+        with tempfile.TemporaryDirectory() as d:
+            with patch.dict("os.environ", {}, clear=False):
+                os.environ.pop("BOT_BOTTLE_BROKER_SECRET", None)
+                with self.assertRaises(SystemExit):
+                    main(["--db", str(Path(d) / "r.db"), "--broker", "http"])
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/unit/test_orchestrator_service.py

@@ -11,7 +11,12 @@ from contextlib import closing
 from pathlib import Path
 from unittest.mock import patch
 
-from bot_bottle.orchestrator.broker import LaunchBroker, LaunchRequest, StubBroker
+from bot_bottle.orchestrator.broker import (
+    BrokerUnavailableError,
+    LaunchBroker,
+    LaunchRequest,
+    StubBroker,
+)
 from bot_bottle.orchestrator.store.registry_store import RegistryStore
 from bot_bottle.orchestrator.service import OrchestratorCore
 from bot_bottle.orchestrator.store.secret_store import new_env_var_secret
@@ -25,8 +30,8 @@ from bot_bottle.orchestrator.supervisor import (
 
 
 class _FailingBroker(LaunchBroker):
-    """Verifies the token like any broker, then fails the launch — to
-    exercise the orchestrator's registry rollback."""
+    """Verifies the token like any broker, then fails the launch *definitely* —
+    to exercise the orchestrator's registry rollback."""
 
     def _launch(self, req: LaunchRequest) -> None:
         raise RuntimeError("launch failed")
@@ -35,6 +40,18 @@ class _FailingBroker(LaunchBroker):
         pass
 
 
+class _UnavailableBroker(LaunchBroker):
+    """Verifies the token, then raises the *ambiguous* BrokerUnavailableError —
+    the host may already have launched — so the orchestrator must KEEP the
+    registry row rather than orphan a running container."""
+
+    def _launch(self, req: LaunchRequest) -> None:
+        raise BrokerUnavailableError("delivery dropped after send")
+
+    def _teardown(self, req: LaunchRequest) -> None:
+        pass
+
+
 class TestOrchestrator(unittest.TestCase):
     def setUp(self) -> None:
         self._tmp = tempfile.TemporaryDirectory()
@@ -136,11 +153,20 @@ class TestOrchestrator(unittest.TestCase):
         self.assertIsNotNone(self.orch.resolve("10.243.0.3", rec.identity_token))
         self.assertIsNone(self.orch.resolve("10.243.0.3", "wrong-token"))
 
-    def test_launch_rolls_back_registry_on_broker_failure(self) -> None:
+    def test_launch_rolls_back_registry_on_definite_broker_failure(self) -> None:
         orch = OrchestratorCore(self.store, _FailingBroker(self.secret), self.secret)
         with self.assertRaises(RuntimeError):
             orch.launch_bottle("10.243.0.9")
-        self.assertEqual([], self.store.all())  # no orphan
+        self.assertEqual([], self.store.all())  # no orphan row
+
+    def test_launch_keeps_registry_on_ambiguous_broker_failure(self) -> None:
+        # The host may already have launched the bottle before the response was
+        # lost, so deregistering would orphan a running container with no row.
+        # The row is kept for reconcile to reap iff the bottle is not live.
+        orch = OrchestratorCore(self.store, _UnavailableBroker(self.secret), self.secret)
+        with self.assertRaises(BrokerUnavailableError):
+            orch.launch_bottle("10.243.0.9")
+        self.assertEqual(1, len(self.store.all()))  # row survives — no orphan container
 
     def test_gateway_status_reports_unconfigured(self) -> None:
         # The orchestrator no longer owns a standalone gateway lifecycle; the