test(mosaic): wait for broker socket readiness

docs/TASKS.md

@@ -64,7 +64,7 @@ Active workstream is **W1 — Federation v1**. Workers should:
 | FCM-M3-002 | in-progress | Add isolated systemd/tmux lifecycle, drift, socket, unmanaged-session, crash, and rollback acceptance coverage                                                         | #758  | sonnet        | mosaicstack/stack | `test/758-reconciler-lifecycle-gates`   | FCM-M3-001                                     | 25K      | Canonical v2 named-socket + legacy-v1 default-server boundaries; fake adapters/temp fixtures only                                                                                                                  |
 | FCM-M4-001 | done        | Implement field-complete v1-to-v2 inventory/preview/migrator with alias, lifecycle, env-quarantine, and remote/connector disposition evidence                          | #758  | codex         | mosaicstack/stack | `feat/758-v1-v2-migrator`               | FCM-M1-003, FCM-M3-001                         | 35K      | PR #788; final head `d63bb0206a1d312ab8352ec1d3ca3631146b0baa`; tree `4da210da9a71b035130d4160a4a2e691bdfde2da`; squash `9745bc3f29c26b021a478b7ad03cfb494f6c9de3`; descendant-main pipeline 1855 terminal success |
 | FCM-M4-002 | not-started | Add reversible canary migration, rollback, stale-projection/orphan classification, and current-host 9-managed/3-unmanaged fixture coverage                             | #758  | sonnet        | mosaicstack/stack | `test/758-migration-rollback-gates`     | FCM-M4-001, FCM-M3-002                         | 25K      | HOLD: never starts a previously stopped agent or kills an unproven unmanaged session; not authorized by FCM-M5-001                                                                                                 |
-| FCM-M5-001 | done        | Deliver the accepted fleet documentation IA, how-to/operations/migration references, and link/example validation                                                       | #758  | haiku         | mosaicstack/stack | `docs/758-fleet-config-operator-docs`   | FCM-M1-003, FCM-M2-002, FCM-M3-001, FCM-M4-001 | 24K      | #789 squash `627cf2bb`; exact-head RoR (head `a39bafb8`) and PR/main terminal-green CI 1907; accepted fleet documentation IA, how-to/operations/migration references, and link/example validation delivered        |
+| FCM-M5-001 | in-progress | Deliver the accepted fleet documentation IA, how-to/operations/migration references, and link/example validation                                                       | #758  | haiku         | mosaicstack/stack | `docs/758-fleet-config-operator-docs`   | FCM-M1-003, FCM-M2-002, FCM-M3-001, FCM-M4-001 | 24K      | Sole owner: this FCM-M5-001 delivery on the recorded branch; must close every checklist item or record an approved deferral                                                                                        |
 | FCM-M5-002 | not-started | Package/update asset-drift checks, rolling local canary, independent validation certificate, and release evidence                                                      | #758  | sonnet        | mosaicstack/stack | `feat/758-fleet-config-release-gate`    | FCM-M3-002, FCM-M4-002, FCM-M5-001             | 30K      | HOLD: final #758 gate; quality, independent code/security review, validator certificate, merge-gate approval, and green CI remain out of M5-001                                                                    |
 
 ## Thin-core prompt diet (#528) — feat/contract-thin-core

packages/mosaic/src/lease-broker/recovery_runtime_unittest.py

@@ -31,17 +31,26 @@ PI_EXTENSION = FRAMEWORK / "runtime/pi/mosaic-extension.ts"
 
 
 def request(socket_path: Path, value: dict[str, object]) -> dict[str, object]:
-    with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as connection:
-        connection.settimeout(3.0)
-        connection.connect(str(socket_path))
-        connection.sendall((json.dumps(value, separators=(",", ":")) + "\n").encode())
-        connection.shutdown(socket.SHUT_WR)
-        response = bytearray()
-        while True:
-            chunk = connection.recv(4096)
-            if not chunk:
-                break
-            response.extend(chunk)
+    deadline = time.monotonic() + 5.0
+    while True:
+        with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as connection:
+            connection.settimeout(3.0)
+            try:
+                connection.connect(str(socket_path))
+            except ConnectionRefusedError:
+                if time.monotonic() >= deadline:
+                    raise
+                time.sleep(0.02)
+                continue
+            connection.sendall((json.dumps(value, separators=(",", ":")) + "\n").encode())
+            connection.shutdown(socket.SHUT_WR)
+            response = bytearray()
+            while True:
+                chunk = connection.recv(4096)
+                if not chunk:
+                    break
+                response.extend(chunk)
+        break
     if not response.endswith(b"\n") or response.count(b"\n") != 1:
         raise AssertionError(f"unframed broker response: {bytes(response)!r}")
     reply = json.loads(response[:-1])