refactor: split bot.py into runtime/dispatch/worker modules; add retry scheduler, route TTL, ack tracking, follow-up screener, structured event log, and test suite

tests/test_ack_hash.py

@@ -0,0 +1,42 @@
+"""ACK-hash stability across retry rebuilds.
+
+The retry scheduler must be able to recompute the expected ACK CRC using the
+same plaintext (ts + attempt byte + text) that the receiver will compute against.
+"""
+
+from __future__ import annotations
+
+from orac.crypto import build_peer_plaintext
+from orac.meshcore import compute_ack_hash
+
+
+def test_ack_hash_stable_for_same_inputs() -> None:
+    ts = 1700000000
+    pt1 = build_peer_plaintext("hello", ts=ts, attempt=0)
+    pt2 = build_peer_plaintext("hello", ts=ts, attempt=0)
+    sender = b"\x11" * 32
+    assert compute_ack_hash(pt1, sender) == compute_ack_hash(pt2, sender)
+
+
+def test_ack_hash_changes_with_attempt_byte() -> None:
+    ts = 1700000000
+    pt0 = build_peer_plaintext("hello", ts=ts, attempt=0)
+    pt1 = build_peer_plaintext("hello", ts=ts, attempt=1)
+    sender = b"\x22" * 32
+    assert compute_ack_hash(pt0, sender) != compute_ack_hash(pt1, sender)
+
+
+def test_ack_hash_changes_with_text() -> None:
+    ts = 1700000000
+    sender = b"\x33" * 32
+    a = compute_ack_hash(build_peer_plaintext("hello", ts=ts, attempt=0), sender)
+    b = compute_ack_hash(build_peer_plaintext("world", ts=ts, attempt=0), sender)
+    assert a != b
+
+
+def test_ack_hash_changes_with_sender() -> None:
+    ts = 1700000000
+    pt = build_peer_plaintext("hello", ts=ts, attempt=0)
+    a = compute_ack_hash(pt, b"\x44" * 32)
+    b = compute_ack_hash(pt, b"\x55" * 32)
+    assert a != b