review: iteration-3 fixes (convergence pass)

- ci-cd.md phrasing made time-invariant (true before and after the
  visibility flip; the prior wording asserted a state not yet real).
- ui-shot: liveness check before the tap QMP call too — the commit-message
  claim of "before every QMP call" is now actually true.
- busybox fetcher checks its pin before downloading, mirroring the
  kernel-tarball fetcher's ordering.
- Fragment disable-arm: absence of a deps-gated symbol is a valid disable
  outcome; only "still set" is fatal (the iteration-2 symmetrization
  overcorrected). Negative-tested both directions under set -e.

Iteration 3 produced four findings, none blocking, all applied — the
recursive review is converged.

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

build/build-kernel.sh

@@ -129,11 +129,14 @@ if [ -n "${WARDEN_KCONFIG_FRAGMENT:-}" ]; then
           frag_fail=1
         } ;;
       "# CONFIG_"*" is not set")
-        # Symmetric with the enable arm: the exact disable line must be
-        # present. A symbol absent entirely means a typo'd/renamed option,
-        # not a successful disable.
-        grep -qxF "$line" "$SRC/.config" || {
-          echo "FATAL: fragment line '$line' not reflected in the final .config" >&2
+        # A disable succeeded if the symbol is NOT set: Kconfig writes either
+        # the literal "is not set" line or (when dependencies gate the symbol
+        # out) nothing at all — both are valid outcomes. Only "still =value"
+        # is a failed disable. (A typo'd symbol disables nothing and is
+        # harmless by construction.)
+        opt="${line#\# }"; opt="${opt% is not set}"
+        grep -qE "^$opt=" "$SRC/.config" && {
+          echo "FATAL: fragment disabled '$opt' but it is still set in the final .config" >&2
           frag_fail=1
         } ;;
     esac

docs/ci-cd.md

@@ -1,9 +1,9 @@
 # CI/CD
 
 `.github/workflows/ci.yml` — every job runs on GitHub-hosted `ubuntu-latest`.
-No self-hosted runner is (or may be) reachable from this repo's workflows:
-the repo is public, and a fork PR that gets one approved run could
-otherwise execute code on private infrastructure (ADR-0007).
+No self-hosted runner is (or may be) reachable from this repo's workflows —
+on a public repo, a fork PR that gets one approved run could otherwise
+execute code on private infrastructure (ADR-0007).
 
 ## Jobs
 

qemu/lib.sh

@@ -16,14 +16,16 @@ qemu_get_busybox() {
   local out="${OUT:-$QEMU_DIR/out}"
   mkdir -p "$out"
   BB="${BUSYBOX:-$out/busybox-armv7l}"
-  if [ ! -f "$BB" ]; then
-    qemu_log "downloading $BB_URL"
-    curl --retry 3 --retry-delay 5 --retry-connrefused -fSL "$BB_URL" -o "$BB"
-  fi
+  # Pin first: a missing pin refuses BEFORE downloading, same ordering as
+  # build/fetch-kernel-tarball.sh.
   [ -f "$sha_file" ] || {
     echo "FATAL: no pinned sha256 for busybox (expected $sha_file) — refusing to build from an unverified binary" >&2
     exit 1
   }
+  if [ ! -f "$BB" ]; then
+    qemu_log "downloading $BB_URL"
+    curl --retry 3 --retry-delay 5 --retry-connrefused -fSL "$BB_URL" -o "$BB"
+  fi
   local want got
   want="$(cat "$sha_file")"
   got="$(sha256sum "$BB" | awk '{print $1}')"

qemu/tests/ui-shot.sh

@@ -123,6 +123,7 @@ done
 # Tap the "Metrics" tab: pixel (373,40) of 720x720 scaled to the QMP absolute
 # range 0..32767 — switching tabs must repaint the content area. Poll for the
 # repaint rather than guessing a delay.
+vm_alive_or_die
 qmp tap 16975 1820
 changed=0
 # 90s, matching the first-frame budget: TCG repaints are CPU-bound and a