fix(smoke): UI presence is the caller's claim, not every lane's assumption

Making REQUIRE_UI unconditional broke all three pr-smoke legs:

  FAIL 15a: SMOKE_REQUIRE_UI=1 but this binary serves no embedded UI assets

The PR lane runs scripts/build.sh WITHOUT --with-ui on purpose, so an npm
frontend build does not land on every product PR. Demanding embedded assets
there asserts a property that lane deliberately does not produce.

The guard still exists where it means something: scripts/ci/smoke-artifact.sh
builds --with-ui, packages the real archive and smokes the EXTRACTED result, so
it exports SMOKE_REQUIRE_UI=1 and a frontend-less binary fails there. That is
the lane whose whole job is release fidelity.

Deliberately NOT fixed by adding --with-ui to pr.yml: that would put `npm ci &&
npm run build` on three runners for every product PR to re-prove something the
dry-run and release lanes already gate. PR CI cost is not free and this branch
should not quietly raise it.

Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

scripts/ci/smoke-artifact.sh

@@ -55,6 +55,9 @@ for arg in "$@"; do
 done
 [ -n "$GOOS" ] && [ -n "$GOARCH" ] || { usage >&2; exit 2; }
 UI_FLAG=(--with-ui)
+# This lane builds and packages the SHIPPED composition, so a binary that serves
+# no frontend is a defect here, not a documented skip.
+export SMOKE_REQUIRE_UI=1
 case "$GOARCH" in
 *-portable) BUILD_ARGS+=("STATIC=1") ;;
 esac

scripts/smoke-local.sh

@@ -22,9 +22,11 @@ destination override neutralized.
 Arguments:
   <binary>     Product binary to smoke (e.g. build/c/codebase-memory-mcp).
 
-One composition ships and it carries the embedded UI, so Phase 15's "no assets"
-outcome is always a FAILURE here (SMOKE_REQUIRE_UI=1): a binary built without
---with-ui cannot pass this smoke.
+Environment:
+  SMOKE_REQUIRE_UI=1   Phase 15's "no embedded assets" SKIP becomes a FAILURE.
+                       Set by scripts/ci/smoke-artifact.sh, which builds and
+                       packages the shipped --with-ui composition. Unset in the
+                       fast PR lane, which builds without the frontend.
 
 Environment:
   CBM_SMOKE_ARTIFACT_DIR   Release mode: an EXTRACTED release artifact
@@ -56,9 +58,12 @@ if [ ! -x "$BINARY" ]; then
     echo "smoke-local: binary is not executable: $BINARY" >&2
     exit 2
 fi
-# Every shipped binary carries the embedded UI, so Phase 15's documented
-# "no embedded assets" SKIP is always a failure here.
-REQUIRE_UI=1
+# Whether the UI must be present is the CALLER's claim, not this script's:
+# scripts/ci/smoke-artifact.sh builds --with-ui and packages the real archive, so
+# it sets SMOKE_REQUIRE_UI=1 and Phase 15's "no embedded assets" SKIP becomes a
+# FAILURE there. The fast PR lane deliberately builds without the frontend to
+# skip an npm build on every product PR, so it must not assert UI presence.
+REQUIRE_UI="${SMOKE_REQUIRE_UI:-0}"
 
 # Unset (the local + PR default): synthesize the release sidecars from this
 # checkout. Set: take them from an EXTRACTED release artifact, so the release

scripts/smoke-test.sh

@@ -3506,10 +3506,12 @@ fi
 # ── Phase 15: UI HTTP server reachability ──
 # Only runs if the binary was built with embedded UI assets.
 #
-# SMOKE_REQUIRE_UI=1 (set by the wrappers for a -ui variant) makes the
-# no-assets outcome a FAILURE instead of a SKIP: a ui run that smoked a
-# standard binary under a ui name would otherwise pass green, and a skip that
-# cannot fail is not a gate.
+# SMOKE_REQUIRE_UI=1 makes the no-assets outcome a FAILURE instead of a SKIP.
+# scripts/ci/smoke-artifact.sh sets it because that lane builds --with-ui and
+# packages the real archive, so a binary serving no frontend is a defect there.
+# The fast PR lane builds without the frontend on purpose and leaves it unset --
+# a skip that cannot fail is not a gate, but neither is asserting a property the
+# lane deliberately does not produce.
 SMOKE_REQUIRE_UI="${SMOKE_REQUIRE_UI:-0}"
 smoke_ui_missing() {
   if [ "$SMOKE_REQUIRE_UI" = "1" ]; then

test-infrastructure/vm/vm-smoke.sh

@@ -73,9 +73,12 @@ case "$SMOKE_ARCH" in
 arm64 | amd64) ;;
 *) echo "vm-smoke: SMOKE_ARCH must be arm64 or amd64. Please consult --help." >&2; exit 2 ;;
 esac
-# Every shipped binary carries the embedded UI, so Phase 15's documented
-# "no embedded assets" SKIP is always a failure here.
-REQUIRE_UI=1
+# Whether the UI must be present is the CALLER's claim, not this script's:
+# scripts/ci/smoke-artifact.sh builds --with-ui and packages the real archive, so
+# it sets SMOKE_REQUIRE_UI=1 and Phase 15's "no embedded assets" SKIP becomes a
+# FAILURE there. The fast PR lane deliberately builds without the frontend to
+# skip an npm build on every product PR, so it must not assert UI presence.
+REQUIRE_UI="${SMOKE_REQUIRE_UI:-0}"
 
 PROFILE_ROOT="$(cygpath -u "$USERPROFILE")"
 SMOKE_DIR="$(mktemp -d "$PROFILE_ROOT/cbm-vm-smoke.XXXXXX")"