diff --git a/shared/build-lib.sh b/shared/build-lib.sh
index 8f13165..1440950 100755
--- a/shared/build-lib.sh
+++ b/shared/build-lib.sh
@@ -131,21 +131,22 @@ _validate_semver() {
     case "$_v3" in '' | *[!0-9]*) _bad ;; esac
 }
 
-# Walk backwards from HEAD until a non-auto-commit is found, return its
-# short SHA. Auto-commits are recognised by their canonical commit-
-# message prefixes:
+# Walk backwards from HEAD until a non-auto-commit is found, return the
+# resolved git ref (e.g. "HEAD~2"). Auto-commits are recognised by their
+# canonical commit-message prefixes:
 #
 #   - "chore(embedded): cut v<X.Y.Z>-beta"   (beta auto-commit, build:993)
 #   - "release: v<X.Y.Z> lockstep"           (stable auto-commit, build:986)
 #
-# Used by compute_build_label to embed a stable source-SHA into beta
-# labels without triggering the embedded-commit recursion: HEAD shifts
-# when embedded bytes change, but the source SHA returned here stays
-# the same as long as the underlying source hasn't moved.
+# Used by the build-label helpers to derive a stable identifier (short
+# SHA, three-word slug) from the underlying source state. The source
+# ref is invariant across the auto-commit step (HEAD shifts when
+# embedded bytes change), so a re-run on the same source state produces
+# the same identifiers and no spurious commit.
 #
-# Falls back to plain `HEAD` short SHA when the walk doesn't find a
-# non-auto-commit in the first 32 commits (defensive cap).
-_source_commit_short_sha() {
+# Defensive cap: stops walking after 32 commits and returns whatever
+# ref was reached.
+_source_commit_ref() {
     _i=0
     _ref="HEAD"
     while [ "$_i" -lt 32 ]; do
@@ -159,7 +160,40 @@ _source_commit_short_sha() {
         esac
         break
     done
-    git -C "$root_dir" rev-parse --short=7 "$_ref" 2>/dev/null || echo "unknown"
+    echo "$_ref"
+}
+
+# Three-word slug derived deterministically from the source commit's
+# full SHA. Same source state → same slug; survives embedded auto-
+# commits by deferring to _source_commit_ref.
+#
+# Three 4-hex-char chunks of the SHA are taken modulo the wordlist
+# length (shared/build-words.txt). 283 words × 3 = 22M combinations,
+# enough that a tester eyeballing two beta builds can tell at a glance
+# whether they're running the same source.
+#
+# Format: "word-word-word" (lowercase, hyphen-separated).
+_source_commit_slug() {
+    _ref=$(_source_commit_ref)
+    _full_sha=$(git -C "$root_dir" rev-parse "$_ref" 2>/dev/null || echo "0000000000000000")
+    _words_file="$root_dir/shared/build-words.txt"
+    if [ ! -f "$_words_file" ]; then
+        # Fall back to plain short SHA if the wordlist is missing
+        # (e.g. running from a checkout that predates this feature).
+        git -C "$root_dir" rev-parse --short=7 "$_ref" 2>/dev/null || echo "unknown"
+        return
+    fi
+    _wc=$(awk 'END{print NR}' "$_words_file")
+    _h1=$(echo "$_full_sha" | cut -c 1-4)
+    _h2=$(echo "$_full_sha" | cut -c 5-8)
+    _h3=$(echo "$_full_sha" | cut -c 9-12)
+    _n1=$(( (0x$_h1 % _wc) + 1 ))
+    _n2=$(( (0x$_h2 % _wc) + 1 ))
+    _n3=$(( (0x$_h3 % _wc) + 1 ))
+    _w1=$(awk -v n="$_n1" 'NR==n{print; exit}' "$_words_file")
+    _w2=$(awk -v n="$_n2" 'NR==n{print; exit}' "$_words_file")
+    _w3=$(awk -v n="$_n3" 'NR==n{print; exit}' "$_words_file")
+    echo "${_w1}-${_w2}-${_w3}"
 }
 
 # Compute build label and channel. Reads positional args:
@@ -218,17 +252,19 @@ compute_build_label() {
         alpha | beta)
             channel="$_arg"
             _date=$(date -u +"%Y-%m-%d")
-            # Resolve the *source* SHA — the most recent commit that is
-            # not itself an embedded-files auto-commit. This stays stable
-            # across the build's auto-commit step (build:971-995) which
-            # advances HEAD by one when embedded bytes change. Using
-            # HEAD directly here would create an infinite loop: each cut
-            # would update the embedded label with the new chore-commit
-            # SHA, which would in turn require another chore commit.
-            # The source SHA is invariant across embedded auto-commits
-            # so the second cut on the same source state is a no-op.
-            _src_sha=$(_source_commit_short_sha)
-            build_label="v${_next_stable}-${channel} · ${_date} · g${_src_sha}"
+            # Three-word slug derived from the *source* SHA — see
+            # _source_commit_slug. Two builds carrying the same slug
+            # were cut from the same source state, so a tester can
+            # glance at the on-page label and confirm "yes, this is
+            # the cobalt-otter-meadow build I was emailed about" without
+            # having to look up a SHA. The slug is invariant across
+            # the embedded auto-commit step (build:971-995) so a re-cut
+            # on unchanged source produces the same slug, no spurious
+            # commit. Full source SHA is available via the binary's
+            # `--version` output and the chart appVersion for any case
+            # where exact provenance matters.
+            _slug=$(_source_commit_slug)
+            build_label="v${_next_stable}-${channel} · ${_date} · ${_slug}"
             _emit_build_label_sidecar "$_tool"
             return 0
             ;;
diff --git a/shared/build-words.txt b/shared/build-words.txt
new file mode 100644
index 0000000..45b3fa6
--- /dev/null
+++ b/shared/build-words.txt
@@ -0,0 +1,283 @@
+acorn
+agate
+alder
+almond
+amber
+anchor
+angle
+antler
+apple
+apricot
+arbor
+arch
+arrow
+ashen
+aspen
+atlas
+attic
+auburn
+aurora
+azure
+badge
+bagel
+ballad
+balm
+banner
+barn
+basil
+basin
+basket
+beacon
+beam
+bear
+beech
+beetle
+berry
+biscuit
+blanket
+blossom
+boat
+bonnet
+book
+boulder
+brass
+bread
+breeze
+brick
+bridge
+brook
+broom
+bubble
+bucket
+buckle
+button
+cabin
+cable
+cactus
+cake
+candle
+canvas
+canyon
+carpet
+cart
+cedar
+chair
+chalk
+chamber
+chapel
+charm
+cherry
+chime
+cinder
+citrus
+clay
+cliff
+cloud
+clover
+cluster
+coal
+coast
+cobble
+cocoa
+coin
+comet
+compass
+copper
+cottage
+cove
+cradle
+crane
+crater
+creek
+crescent
+cricket
+crystal
+daisy
+dawn
+deer
+denim
+diamond
+ditch
+dock
+dolphin
+dome
+drift
+drum
+dune
+dusk
+eagle
+ember
+emerald
+fable
+falcon
+feather
+fence
+fern
+fiddle
+finch
+flag
+flame
+flask
+flax
+fleece
+flint
+flute
+foam
+forest
+fork
+fort
+fountain
+fox
+garden
+garnet
+gear
+ginger
+glacier
+glade
+glass
+globe
+gold
+granite
+grass
+grove
+hammer
+harbor
+harp
+harvest
+hazel
+hearth
+heron
+hill
+hinge
+hive
+holly
+hook
+horizon
+horn
+hut
+indigo
+iris
+iron
+island
+ivory
+ivy
+jade
+jasper
+juniper
+kayak
+kelp
+kettle
+key
+kiln
+kite
+lake
+lamp
+lantern
+lark
+laurel
+leaf
+ledge
+lemon
+lens
+lilac
+lily
+linen
+locust
+log
+loom
+lotus
+maple
+marble
+marigold
+marsh
+mast
+meadow
+melon
+mesa
+meteor
+mint
+mirror
+mist
+mitten
+moon
+moor
+moss
+mug
+nectar
+nest
+niche
+nickel
+nimbus
+oak
+oasis
+ocean
+onyx
+opal
+orbit
+orchard
+otter
+owl
+oyster
+paddle
+palm
+panel
+parrot
+patio
+pearl
+pebble
+pelican
+pepper
+perch
+pier
+pillow
+pine
+pipe
+plank
+plaza
+pocket
+pond
+poplar
+port
+prairie
+prism
+puddle
+quarry
+quartz
+quill
+quilt
+rabbit
+raft
+rain
+ranch
+raven
+reed
+reef
+ribbon
+ridge
+river
+robin
+rock
+rope
+saddle
+sage
+sail
+salt
+sand
+sapphire
+sash
+satin
+scarf
+sea
+seal
+seed
+shawl
+shield
+shore
+shrub
+silver
+silo
+slope
+smoke
+snail
+snow
+spire