fix(issue-5): address phase 1 cross-review findings (R1, R2, F-1)

Three reviewers examined fc0bd96..8def235. Codex and Claude each reproduced a
defect; all three findings were re-verified here before being accepted, and none
were rebutted.

R1 (codex) — the shell helpers ran `python -m lib_py.delegation.cli`. For -m,
sys.path[0] is the working directory, which therefore beats PYTHONPATH: with cwd
inside a tree containing lib_py, the live package won even with the frozen path
listed first. The documented B-13 guarantee for this path did not hold.
Reproduced, then replaced with an explicit bootstrap that inserts SKILL_DIR
itself. cwd is left alone, because the registry and audit-log paths are relative
to it. The file-based shim path was never affected.

R2 (codex) — the persistent connection was reused on host and port alone. Two
jobs sharing an endpoint but carrying different credentials or TLS settings
silently published over the first connection. Reproduced (the client factory ran
once, under the first account, with TLS off). The guard now compares an
immutable snapshot of the whole connection identity and names only the differing
field, never its value.

F-1 (claude) — paho queues a publish issued while disconnected and raises
RuntimeError from wait_for_publish. RuntimeError is deliberately outside the
retry tuple, so the one state a persistent connection exists to survive, the gap
between a drop and paho's reconnect, failed on the first attempt. Confirmed
against paho 2.1.0. That single condition is now translated into a retryable
error; the tuple is unchanged, so genuine programming errors are still not
retried.

Two fixtures were hiding these: FakeInfo had no rc and never raised. It now
mirrors paho's contract, which is what makes the new tests meaningful.

Also folds in the duplication both Claude (O-1) and I had flagged: the CLI path
kept its own copy of connect-publish-disconnect plus its own timeout constants.
_publish_once now delegates to OneShotPublisher.publish_raw, so a transport fix
lands once. Having two copies is exactly why these bugs existed in one of them.

Documentation corrected rather than defended: the benchmark's rationale for
keeping three forks was imprecise (the || true already guarantees rc 0; the
lookup buys quietness and legacy parity), SKILL.md no longer claims PYTHONPATH
decides the frozen path, and the daemon's directory creation is recorded as a
deliberate difference. Trailing whitespace inherited by the relocated file is
stripped, so the commit range is now clean too.

Verified: each regression fails against the pre-fix code and passes after
(R1 1, R2 4, F-1 1). 66 phase-1 tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UrDNJkHmm18uu7n7JwV5Qd

.agents/skills/lib_py/delegation/publish_event.py

@@ -27,7 +27,6 @@ import hmac
 import json
 import logging
 import sys
-import time
 from typing import Any, Dict, Optional
 
 from lib_py.delegation import mqtt_common
@@ -38,7 +37,6 @@ from lib_py.delegation.mqtt_common import (
     broker_config_from_job,
     events_topic_for,
     load_job,
-    make_client,
     next_seq,
     with_retry,
 )
@@ -55,8 +53,13 @@ EVENT_TO_STATUS = {
     "cancelled": "cancelled",
 }
 
-CONNECT_ACK_TIMEOUT = 10  # seconds to wait for CONNACK
-PUBLISH_ACK_TIMEOUT = 5   # seconds to wait for QoS-1 PUBACK
+# Re-exported from the transport module, which owns the single implementation.
+# Two copies of these numbers meant tuning one silently diverged from the other.
+from lib_py.delegation.publisher import (  # noqa: F401  (re-exported for callers)
+    CONNECT_ACK_TIMEOUT,
+    PUBLISH_ACK_TIMEOUT,
+    OneShotPublisher,
+)
 
 
 def build_payload(
@@ -91,37 +94,12 @@ def build_payload(
 def _publish_once(config, topic: str, body: bytes, retain: bool) -> None:
     """Connect, publish one QoS-1 message, wait for the broker ACK, disconnect.
 
-    Raises on any failure so ``with_retry`` can re-run the whole sequence (a
-    fresh connection per attempt is the robust choice for a PoC)."""
-    client = make_client("publisher", config)
-    connected = {"rc": None}
-
-    def on_connect(_c, _u, _flags, reason_code, _props):
-        connected["rc"] = reason_code
-
-    client.on_connect = on_connect
-    client.connect(config.host, config.port, config.keepalive)
-    client.loop_start()
-    try:
-        # Wait for CONNACK so we fail fast on auth/TLS errors.
-        deadline = time.monotonic() + CONNECT_ACK_TIMEOUT
-        while connected["rc"] is None and time.monotonic() < deadline:
-            time.sleep(0.05)
-        if connected["rc"] is None:
-            raise TimeoutError("no CONNACK from broker")
-        if mqtt_common.reason_code_value(connected["rc"]) != 0:
-            raise ConnectionError(f"broker refused connection: rc={connected['rc']}")
-
-        info = client.publish(topic, payload=body, qos=1, retain=retain)
-        info.wait_for_publish(timeout=PUBLISH_ACK_TIMEOUT)
-        if not info.is_published():
-            raise TimeoutError("publish not acknowledged within timeout")
-    finally:
-        client.loop_stop()
-        try:
-            client.disconnect()
-        except Exception:  # pragma: no cover - disconnect best effort
-            pass
+    Delegates to the transport module so the CLI path and the service path share
+    one implementation. Keeping a second copy here is what let the persistent
+    transport's handshake and not-connected bugs exist in only one of them.
+    Raises on any failure so ``with_retry`` can re-run the whole sequence.
+    """
+    OneShotPublisher().publish_raw(config, topic, body, retain)
 
 
 class PreparedEvent(object):