refactor(daemon): remove unused source-label socket API (closes #21)

docs/PONYTAIL_REVIEW_2026-06-20.md

@@ -18,7 +18,7 @@
 > - **C1** `MerkleTree.get_proof` deleted — its only caller (the stage wrapper) went in Tier 1, so it is now confirmed dead.
 > - **R5 (partial)** `bytes_to_sdr` + its roundtrip test deleted (dead deserialization; `sdr_to_bytes` kept — production). **`hamming_distance` KEPT** — it backs real encoder-locality contract tests (similar→close, different→far, identity→0); deleting it would cost coverage, not just lines. Deliberate deviation from the Tier 2 line item.
 > - **M3** `apply_modulation` + its test deleted. Rule 10 (anchor gain = 1.0) stays covered by `compute_gain` tests (test_profile) and the production `compute_injection_gain` tests (test_cogexec) — no coverage lost.
-> - **Tier 5 (D3)** still parked — needs a roadmap call (will `agents/harness.py` adopt the second socket API?). Untouched.
+> - **Tier 5 (D3)** RESOLVED — **removed** (issue #21, decision: no `agents/harness.py` adoption). Deleted `acquire_listen_socket` + `try_launchd_socket`/`try_systemd_socket`/`bind_dev_socket` + their test module (~90 lines). Production `acquire_listening_socket` is the sole path.
 > Verification: `cargo test -p hippocampus` 40/0; py_compile + import + dangling-ref grep clean.
 
 Scope: **over-engineering and unnecessary complexity only.** Not correctness,

python/harlo/daemon/socket_activation.py

@@ -1,34 +1,24 @@
 """Listening-socket acquisition for the Rule-1 daemon.
 
-Two acquisition entry points coexist here, merged from two independent
-C1/D69 fixes. Both try, in order: launchd (launch_activate_socket(3),
-macOS) → systemd (LISTEN_FDS / fd 3, Linux) → dev fallback (bind the UDS
-path ourselves). On macOS the old code only checked the systemd
-LISTEN_FDS protocol, so it always fell through to a dev rebind that
-unlink+rebind the very socket launchd was holding — Rule 1 (0W idle via
-OS socket activation) was never realized on the target platform.
+Acquisition tries, in order: launchd (launch_activate_socket(3), macOS) →
+systemd (LISTEN_FDS / fd 3, Linux) → dev fallback (bind the UDS path
+ourselves). On macOS the old code only checked the systemd LISTEN_FDS
+protocol, so it always fell through to a dev rebind that unlink+rebind the
+very socket launchd was holding — Rule 1 (0W idle via OS socket
+activation) was never realized on the target platform.
 
   - acquire_listening_socket(sock_path, launchd_name) -> (sock, owns_node)
         D69-guarded: refuses to hijack a live listener; owns_node tells
         the caller whether it may unlink the node on exit (True only in
         dev mode — under launchd/systemd the OS owns the node). This is
         the production daemon path (daemon/main.py).
 
-  - acquire_listen_socket(sock_path) -> (sock, source)
-        Returns a source label ("launchd"/"systemd"/"dev") for callers
-        and tests that branch on the acquisition source.
-
-Built for reuse: the agents harness (agents/harness.py:115-127) has the
-identical LISTEN_FDS-only bug and should adopt this module in a
-follow-up, passing its own socket name ("HarloAgents").
-
 Rule 1: this is pure FD acquisition — no polling, no sleep.
 """
 
 from __future__ import annotations
 
 import ctypes
-import ctypes.util
 import errno
 import logging
 import os
@@ -158,103 +148,8 @@ def acquire_listening_socket(
     return sock, True
 
 
-# ---------------------------------------------------------------------------
-# Source-label API (acquire_listen_socket) — retained for callers and tests
-# that branch on the acquisition source string.
-# ponytail: deferred, test-only today (no production caller). Either adopt in
-# agents/harness.py (the intended reuse — see module docstring) or delete
-# acquire_listen_socket + try_launchd/systemd/bind_dev + their tests (~85
-# lines). Decision tracked in issue #21.
-# ---------------------------------------------------------------------------
-
-def try_launchd_socket(name: str = LAUNCHD_SOCKET_NAME) -> socket.socket | None:
-    """Return the launchd-activated listening socket, or ``None``.
-
-    Wraps ``int launch_activate_socket(const char *name, int **fds,
-    size_t *cnt)`` from libSystem (Darwin only). Returns ``None`` on any
-    non-Darwin host, missing symbol, non-zero status, or zero fds — never
-    raises.
-    """
-    if sys.platform != "darwin":
-        return None
-    try:
-        libc = ctypes.CDLL(
-            ctypes.util.find_library("System") or "/usr/lib/libSystem.B.dylib"
-        )
-        fn = libc.launch_activate_socket
-    except (OSError, AttributeError):
-        return None
-
-    fn.restype = ctypes.c_int
-    fn.argtypes = [
-        ctypes.c_char_p,
-        ctypes.POINTER(ctypes.POINTER(ctypes.c_int)),
-        ctypes.POINTER(ctypes.c_size_t),
-    ]
-    fds_ptr = ctypes.POINTER(ctypes.c_int)()
-    count = ctypes.c_size_t(0)
-    try:
-        rc = fn(name.encode("utf-8"), ctypes.byref(fds_ptr), ctypes.byref(count))
-    except Exception:
-        return None
-    if rc != 0 or count.value < 1:
-        return None
-
-    try:
-        fd = fds_ptr[0]
-        sock = socket.fromfd(fd, socket.AF_UNIX, socket.SOCK_STREAM)
-    except Exception:
-        return None
-    finally:
-        # launch_activate_socket malloc's the fd array; free it.
-        try:
-            libc.free.argtypes = [ctypes.c_void_p]
-            libc.free(ctypes.cast(fds_ptr, ctypes.c_void_p))
-        except Exception:
-            pass
-    return sock
-
-
-def try_systemd_socket() -> socket.socket | None:
-    """Return the systemd-activated socket (fd 3), or ``None``."""
-    listen_fds = os.environ.get("LISTEN_FDS")
-    if listen_fds and listen_fds.isdigit() and int(listen_fds) > 0:
-        return socket.fromfd(3, socket.AF_UNIX, socket.SOCK_STREAM)
-    return None
-
-
-def bind_dev_socket(sock_path: str, backlog: int = 5) -> socket.socket:
-    """Dev fallback: bind the UDS path directly."""
-    if os.path.exists(sock_path):
-        os.unlink(sock_path)
-    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-    sock.bind(sock_path)
-    sock.listen(backlog)
-    return sock
-
-
-def acquire_listen_socket(sock_path: str) -> tuple[socket.socket, str]:
-    """Acquire the listening socket. Returns ``(sock, source)``.
-
-    ``source`` is one of ``"launchd"`` / ``"systemd"`` / ``"dev"`` for
-    logging and tests. Prefer ``acquire_listening_socket`` for the
-    production daemon path — it adds the D69 live-listener guard.
-    """
-    sock = try_launchd_socket()
-    if sock is not None:
-        return sock, "launchd"
-    sock = try_systemd_socket()
-    if sock is not None:
-        return sock, "systemd"
-    return bind_dev_socket(sock_path), "dev"
-
-
 __all__ = [
     "LAUNCHD_SOCKET_NAME",
     "acquire_listening_socket",
-    "acquire_listen_socket",
     "adopt_launchd_socket",
-    "bind_dev_socket",
-    "try_launchd_socket",
-    "try_systemd_socket",
 ]