review: iteration-1 fixes across CI, bridge, VM harness, and docs

CI/pipeline:
- KERNEL_TARBALL passed as a YAML env literal '~' was never tilde-expanded
  and would have failed every hosted kernel-build dispatch; the path is now
  exported from the shell. Verified reproducible before the fix.
- Every job gets timeout-minutes; boot smoke uses timeout -k so a wedged
  qemu is SIGKILLed instead of holding the job.
- Tarball fetch + fail-closed sha256 verification deduplicated into
  build/fetch-kernel-tarball.sh (with curl retries), used by build-kernel.sh
  and both CI jobs. busybox fetch gains retries too.
- ccache layer for kernel-build (cache keyed on defconfig+patches) recovers
  the incremental-compile speed the ephemeral-runner move cost.
- build-kernel.sh now asserts every fragment option survived olddefconfig —
  merge_config -m pastes text and Kconfig silently drops unmet symbols.

rs485-bridge:
- pending-buffer cap (2x max RTU ADU) instead of unbounded growth;
  explicit accept-loop error handling with backoff instead of .flatten();
  per-arm inline bounds instead of the string-keyed lookup whose default
  would have mis-bounded a future get-input; control-socket cleanup errors
  surfaced; flag-shaped values rejected in arg parsing; doc example uses a
  private mktemp dir. Test timing margins widened for contended runners
  (gap 25->120ms, 60x margin on the split-frame test).

VM harness:
- stage-1/stage-2 boot scripts share one validated slot parser and one
  by-name populator (qemu/rootfs/etc/warden-lib.sh) — the duplicated
  parser had already diverged on validation; userdata/oem mount failures
  now fail fast with a greppable sentinel; udhcpc fallback keys off the
  interface actually having an address; switch_root applet guarded.
- boot-smoke delegates the qemu invocation to run.sh (machine shape lives
  in ONE place); run.sh port 0 disables a hostfwd.
- mkimage: unknown partition names fail at build time; DISK_END is a max,
  not last-entry; --state keys validated as filenames.
- portal-scenario: mock readiness is asserted (no silent fall-through),
  hostfwd port collisions retried, mount-failure sentinel fails fast.
- ui-shot: fixed sleeps replaced with bounded screendump polling; the
  repaint assertion is real and documented as such. qmp.py loses its
  module-global and gains argv validation.

Docs/scrub: bench-host paths and the site AP name removed from six more
port docs and two evidence tables; path-bearing build artifacts (.elf,
.map) untracked (the 154-byte firmware .bin is path-free and stays);
ADR-0003 marked visibility-superseded by ADR-0007; stale section
cross-reference fixed; flare-edge noted as private for outside readers;
stale root-level review report removed per the new workspace rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018HUayid7W5w7jBdb9Rrj1K

qemu/tests/qmp.py

@@ -11,7 +11,7 @@ import sys
 import time
 
 
-def rpc(sock, obj):
+def rpc(sock, sock_file, obj):
     sock.sendall((json.dumps(obj) + "\n").encode())
     while True:
         line = sock_file.readline()
@@ -29,15 +29,20 @@ def main():
     if len(sys.argv) < 3:
         sys.exit(__doc__)
     path, cmd = sys.argv[1], sys.argv[2]
-    global sock_file
+    need = {"screendump": 4, "tap": 5, "quit": 3}
+    if cmd not in need:
+        sys.exit(f"unknown command {cmd}\n{__doc__}")
+    if len(sys.argv) < need[cmd]:
+        sys.exit(f"{cmd}: missing argument(s)\n{__doc__}")
+
     s = socket.socket(socket.AF_UNIX)
     s.connect(path)
-    sock_file = s.makefile("r")
-    sock_file.readline()  # greeting banner
-    rpc(s, {"execute": "qmp_capabilities"})
+    f = s.makefile("r")
+    f.readline()  # greeting banner
+    rpc(s, f, {"execute": "qmp_capabilities"})
 
     if cmd == "screendump":
-        rpc(s, {"execute": "screendump", "arguments": {"filename": sys.argv[3]}})
+        rpc(s, f, {"execute": "screendump", "arguments": {"filename": sys.argv[3]}})
     elif cmd == "tap":
         x, y = int(sys.argv[3]), int(sys.argv[4])
         press = [
@@ -46,16 +51,14 @@ def main():
             {"type": "btn", "data": {"down": True, "button": "left"}},
         ]
         release = [{"type": "btn", "data": {"down": False, "button": "left"}}]
-        rpc(s, {"execute": "input-send-event", "arguments": {"events": press}})
+        rpc(s, f, {"execute": "input-send-event", "arguments": {"events": press}})
         # Hold the press across several LVGL indev poll periods (33 ms each):
         # an instantaneous press+release lands inside one poll and no click
         # is ever registered.
         time.sleep(0.2)
-        rpc(s, {"execute": "input-send-event", "arguments": {"events": release}})
+        rpc(s, f, {"execute": "input-send-event", "arguments": {"events": release}})
     elif cmd == "quit":
         s.sendall(b'{"execute":"quit"}\n')
-    else:
-        sys.exit(f"unknown command {cmd}")
 
 
 if __name__ == "__main__":