diff --git a/config/llama-mirror-branch.config b/config/llama-mirror-branch.config
new file mode 100644
index 000000000..ad57ae50b
--- /dev/null
+++ b/config/llama-mirror-branch.config
@@ -0,0 +1,29 @@
+# Copyright 2026 bong-water-water-bong
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# The branch of 1bit-MONSTER/llama.cpp that mirrors AMD's HRX line, for the daily bump-hrx run
+# (scripts/bump-hrx-sync.sh): the first line below that is not a comment. With no such line the mirror is
+# `1bit/hrx-vulkan`, as it has always been.
+#
+# Why this is a file: no branch of the fork is ever force-moved (owner, 2026-11-10). When AMD rewrites its line
+# so that its pin no longer descends from the mirror, AMD's new line is pushed to a NEW branch, named for the
+# day, the old mirror is left exactly where it is, and that branch's name goes here. The workflow file is not
+# edited. Order of work for such a move:
+#   1. push AMD's pin to 1bit-MONSTER/llama.cpp as a new branch, e.g. 1bit/hrx-vulkan-20261110 (AMD's history
+#      carries workflow files, so this push needs a token with `workflow` scope);
+#   2. merge that branch into 1bit/hrx-vulkan-patched by an ordinary reviewed PR on the fork;
+#   3. name the branch on a line below, and delete any commit line from config/llama-mirror-hold.config.
+#
+# No branch is named below, so the mirror is 1bit/hrx-vulkan.
diff --git a/docs/hrx.md b/docs/hrx.md
index d9feccefd..7243fbc49 100644
--- a/docs/hrx.md
+++ b/docs/hrx.md
@@ -111,6 +111,13 @@ fails a pin that leaves a gate model's node off HRX.
   the mirror's commit `44ee5710d19f`, and the merge of AMD's rebased line is post-release work. It was added for AMD's 2026-11-09 rebase (engine#1945): taking that pin is a merge of
   149 conflicted files (538 hunks) into `1bit/hrx-vulkan-patched`, measured against the last AMD commit our
   line took.
+- **Which branch is the mirror.** [`config/llama-mirror-branch.config`](../config/llama-mirror-branch.config)
+  names it; with no name there it is `1bit/hrx-vulkan`. The file exists because no branch of the fork is ever
+  force-moved (owner, 2026-11-10): when AMD rewrites its line, AMD's new line is pushed to a new branch named for
+  the day, merged into `1bit/hrx-vulkan-patched` by an ordinary reviewed PR on the fork, and then named in this
+  file, while the old mirror stays where it was. That needs no workflow edit. A name that is not a plain branch
+  name, or that is our own line, is refused. `scripts/bump-hrx-sync.sh mirror-branch` prints the branch a run
+  would use.
 - **The hold.** While [`config/hrx-system-hold.config`](../config/hrx-system-hold.config)
   names a commit, the run does not merge AMD's hrx-system, keeps `third_party/hrx-system`
   where it is, and takes only AMD's llama.cpp changes outside the HRX backend paths
diff --git a/scripts/bump-hrx-sync.sh b/scripts/bump-hrx-sync.sh
index 458577a88..1bde316e3 100755
--- a/scripts/bump-hrx-sync.sh
+++ b/scripts/bump-hrx-sync.sh
@@ -51,6 +51,7 @@ cmd=${1:-}
 DRY_RUN=${DRY_RUN:-0}
 HOLD_FILE=${HOLD_FILE:-config/hrx-system-hold.config}
 LLAMA_HOLD_FILE=${LLAMA_HOLD_FILE:-config/llama-mirror-hold.config}
+LLAMA_MIRROR_FILE=${LLAMA_MIRROR_FILE:-config/llama-mirror-branch.config}
 ENGINE_DIR=$(pwd)
 # The HRX backend paths of the llama.cpp tree (what AMD's hrx-graph line adds on top of ggml).
 # tests/CMakeLists.txt belongs here: it is where the HRX test targets are registered, so it moves
@@ -96,6 +97,26 @@ llama_hold_sha() {
   grep -v '^[[:space:]]*#' "$f" | grep -oE '^[0-9a-f]{40}' | head -n1 || true
 }
 
+# The branch of 1bit-MONSTER/llama.cpp that mirrors AMD's line: the first line of config/llama-mirror-branch.config
+# that is not a comment, or 1bit/hrx-vulkan when the file is absent or names nothing.
+# 2026-11-10 (engine#1945): AMD rebased its line, and the owner's rule is that no branch is ever force-moved. So the
+# old mirror stays where it is, AMD's new line goes to a NEW branch (1bit/hrx-vulkan-<date>), and this file is how the
+# sync is pointed at it -- the workflow file is not edited, and cannot be with the token this repository's lanes have.
+# A name that is not a plain branch name is refused: it ends up inside a refspec.
+llama_mirror_branch() {
+  local f=$LLAMA_MIRROR_FILE name=""
+  case "$f" in /*) ;; *) f=$ENGINE_DIR/$f ;; esac
+  if [ -f "$f" ]; then name=$(grep -v '^[[:space:]]*#' "$f" | grep -v '^[[:space:]]*$' | head -n1 | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' || true); fi
+  [ -n "$name" ] || name=1bit/hrx-vulkan
+  case "$name" in
+    */hrx-vulkan-patched|1bit/hrx-vulkan-patched) die "$LLAMA_MIRROR_FILE names $name, which is our own line, not a mirror of AMD's" >&2 ;;
+  esac
+  if ! [[ "$name" =~ ^[A-Za-z0-9._/-]+$ ]] || [[ "$name" == *..* ]] || [[ "$name" == -* ]] || [[ "$name" == refs/* ]]; then
+    die "$LLAMA_MIRROR_FILE names '$name', which is not a plain branch name" >&2
+  fi
+  echo "$name"
+}
+
 # What a mirror hold means for this run. Reads repo $1; $2 is the held commit (may be empty), $3 the mirror tip,
 # $4 AMD's pin. One word:
 #   none      no commit is held: the sync runs as usual
@@ -148,32 +169,33 @@ sync_llama() {
     warn "could not refresh 1bit-MONSTER/llama.cpp master: $(printf '%s' "$refresh" | head -n1); continuing with the HRX pin sync"
   fi
 
+  local mirror_branch; mirror_branch=$(llama_mirror_branch)
   rm -rf patched && git init -q patched && cd patched
   git remote add fork "$(remote_url 1bit-MONSTER/llama.cpp)"
   git remote add amd https://github.com/AMD-Ecosystem/llama.cpp.git
   git fetch -q --filter=blob:none amd "$AMD_LLAMA"
   git fetch -q --filter=blob:none fork \
-    "1bit/hrx-vulkan:refs/remotes/fork/mirror" "1bit/hrx-vulkan-patched:refs/remotes/fork/patched"
+    "$mirror_branch:refs/remotes/fork/mirror" "1bit/hrx-vulkan-patched:refs/remotes/fork/patched"
   local mirror patched pin=$AMD_LLAMA
   mirror=$(git rev-parse refs/remotes/fork/mirror)
   patched=$(git rev-parse refs/remotes/fork/patched)
-  echo "AMD pin $pin, mirror 1bit/hrx-vulkan $mirror, our line 1bit/hrx-vulkan-patched $patched"
+  echo "AMD pin $pin, mirror $mirror_branch $mirror, our line 1bit/hrx-vulkan-patched $patched"
 
   # 0. A mirror hold (config/llama-mirror-hold.config): the run reports it and moves nothing.
   local lhold; lhold=$(llama_hold_sha)
   case "$(llama_hold_decision . "$lhold" "$mirror" "$pin")" in
     stale)
-      die "$LLAMA_HOLD_FILE holds 1bit/hrx-vulkan at ${lhold:0:12}, but the mirror is ${mirror:0:12}: the hold is out of date. Name the mirror's commit in it, or delete the commit line to let the sync run." ;;
+      die "$LLAMA_HOLD_FILE holds $mirror_branch at ${lhold:0:12}, but the mirror is ${mirror:0:12}: the hold is out of date. Name the mirror's commit in it, or delete the commit line to let the sync run." ;;
     unneeded)
-      die "$LLAMA_HOLD_FILE holds 1bit/hrx-vulkan at ${lhold:0:12}, and AMD's pin ${pin:0:12} contains that commit: an ordinary sync would work. Delete the commit line." ;;
+      die "$LLAMA_HOLD_FILE holds $mirror_branch at ${lhold:0:12}, and AMD's pin ${pin:0:12} contains that commit: an ordinary sync would work. Delete the commit line." ;;
     held)
-      note "1bit/hrx-vulkan is held at ${mirror:0:12} by $LLAMA_HOLD_FILE: AMD's pin ${pin:0:12} does not descend from it (AMD rewrote its line). Nothing was moved; the merge is tracked where the hold file says."
-      summary "- llama.cpp: mirror \`1bit/hrx-vulkan\` HELD at \`${mirror:0:12}\` ($LLAMA_HOLD_FILE); AMD's pin is \`${pin:0:12}\`, on a line that does not contain it. Not merged."
+      note "$mirror_branch is held at ${mirror:0:12} by $LLAMA_HOLD_FILE: AMD's pin ${pin:0:12} does not descend from it (AMD rewrote its line). Nothing was moved; the merge is tracked where the hold file says."
+      summary "- llama.cpp: mirror \`$mirror_branch\` HELD at \`${mirror:0:12}\` ($LLAMA_HOLD_FILE); AMD's pin is \`${pin:0:12}\`, on a line that does not contain it. Not merged."
       # The engine's pin does not move while the mirror is held: `rebased` is what the workflow would pin, and
       # naming the engine's own pin makes its last step say "nothing to move" (our line may be ahead of the pin;
       # moving the pin along it is a reviewed PR of its own, not something a held run does).
       output "rebased=${OURS_LLAMA:-$patched}"
-      output "llama_held=1bit/hrx-vulkan HELD at \`${mirror:0:12}\` by \`$LLAMA_HOLD_FILE\` (AMD's pin is \`${pin:0:12}\`)."
+      output "llama_held=$mirror_branch HELD at \`${mirror:0:12}\` by \`$LLAMA_HOLD_FILE\` (AMD's pin is \`${pin:0:12}\`)."
       output "patches<<EOF
 EOF"
       return 0 ;;
@@ -193,10 +215,10 @@ EOF"
     foreign=$(sed -n 's/^foreign //p' <<< "$off")
     rebased=$(sed -n 's/^rebased //p' <<< "$off")
     if [ -n "$foreign" ]; then
-      die "1bit/hrx-vulkan has commits that are on no branch of AMD-Ecosystem/llama.cpp and have no same-author, same-date, same-subject commit in AMD's pin; the mirror must hold AMD's commits only. Move these to 1bit/hrx-vulkan-patched by hand: $(tr '\n' ';' <<< "$foreign")"
+      die "$mirror_branch has commits that are on no branch of AMD-Ecosystem/llama.cpp and have no same-author, same-date, same-subject commit in AMD's pin; the mirror must hold AMD's commits only. Move these to 1bit/hrx-vulkan-patched by hand: $(tr '\n' ';' <<< "$foreign")"
     fi
     if [ -n "$rebased" ]; then
-      die "AMD rebased its line and dropped the old one: $(wc -l <<< "$rebased" | tr -d ' ') commit(s) of 1bit/hrx-vulkan are on no AMD branch, and each has a commit in AMD's pin ${pin:0:12} with the same author, author date and subject (old new subject: $(tr '\n' ';' <<< "$rebased")). They are AMD's commits, NOT ours: do not move them to 1bit/hrx-vulkan-patched. Merge AMD's pin into 1bit/hrx-vulkan-patched by hand, then move the mirror to the pin."
+      die "AMD rebased its line and dropped the old one: $(wc -l <<< "$rebased" | tr -d ' ') commit(s) of $mirror_branch are on no AMD branch, and each has a commit in AMD's pin ${pin:0:12} with the same author, author date and subject (old new subject: $(tr '\n' ';' <<< "$rebased")). They are AMD's commits, NOT ours: do not move them to 1bit/hrx-vulkan-patched. Merge AMD's pin into 1bit/hrx-vulkan-patched by hand, then move the mirror to the pin."
     fi
     # AMD rewrote history. Find the newest commit of the new pin whose tree equals a commit that
     # descends from the old mirror on some AMD branch (its pre-rewrite equivalent).
@@ -208,7 +230,7 @@ EOF"
       if [ -n "$equiv" ]; then squash=$c; break; fi
     done < <(git -C ../amdrefs log --format='%H %T' "$pin" --not "$mirror")
     if [ -z "$squash" ]; then
-      die "AMD's pin ${pin:0:12} does not contain 1bit/hrx-vulkan ${mirror:0:12} and no AMD commit after it has the same tree as any commit of the new pin; AMD rewrote its history in a way this job cannot map. Merge AMD's pin into 1bit/hrx-vulkan-patched by hand."
+      die "AMD's pin ${pin:0:12} does not contain $mirror_branch ${mirror:0:12} and no AMD commit after it has the same tree as any commit of the new pin; AMD rewrote its history in a way this job cannot map. Merge AMD's pin into 1bit/hrx-vulkan-patched by hand."
     fi
     git fetch -q --filter=blob:none amd "$equiv" 2>/dev/null || git fetch -q --filter=blob:none fork "$equiv"
     ident replace --graft "$squash" "$equiv"
@@ -292,9 +314,9 @@ parent here, so a later full merge still brings them in.")
     if [ "$rewritten" = 1 ]; then
       git tag -f "hrx-vulkan-${mirror:0:12}" "$mirror"
       push fork "refs/tags/hrx-vulkan-${mirror:0:12}"
-      push --force-with-lease="refs/heads/1bit/hrx-vulkan:$mirror" fork "$pin:refs/heads/1bit/hrx-vulkan"
+      push --force-with-lease="refs/heads/$mirror_branch:$mirror" fork "$pin:refs/heads/$mirror_branch"
     else
-      push fork "$pin:refs/heads/1bit/hrx-vulkan"
+      push fork "$pin:refs/heads/$mirror_branch"
     fi
   fi
   output "rebased=$rebased"
@@ -346,5 +368,7 @@ case "$cmd" in
   off-branch) off_branch_commits "${2:?repo}" "${3:?mirror}" "${4:?pin}" ;;
   # The mirror-hold decision alone, on a local repository: llama-hold <repo> <mirror> <pin>, hold file from LLAMA_HOLD_FILE.
   llama-hold) llama_hold_decision "${2:?repo}" "$(llama_hold_sha)" "${3:?mirror}" "${4:?pin}" ;;
+  # The mirror branch this run would use (config/llama-mirror-branch.config, or LLAMA_MIRROR_FILE).
+  mirror-branch) llama_mirror_branch ;;
   *) echo "usage: $0 llama|hrx" >&2; exit 2 ;;
 esac
diff --git a/tests/bump_hrx_sync_test.sh b/tests/bump_hrx_sync_test.sh
index 324a0b90a..7333d91af 100755
--- a/tests/bump_hrx_sync_test.sh
+++ b/tests/bump_hrx_sync_test.sh
@@ -136,5 +136,39 @@ else
   fail "config/llama-mirror-hold.config is in the tree"
 fi
 
+# ---- which branch is the mirror (config/llama-mirror-branch.config) -----------------------------------------
+mb=$work/mirror.config
+branch() { LLAMA_MIRROR_FILE=$mb bash "$script" mirror-branch 2>&1; }
+rm -f "$mb"
+expect "no file: the mirror is 1bit/hrx-vulkan, as it always was" "$(branch)" "1bit/hrx-vulkan"
+printf '# only comments\n\n#   1bit/hrx-vulkan-20261110\n' > "$mb"
+expect "a branch that is only mentioned in a comment changes nothing" "$(branch)" "1bit/hrx-vulkan"
+printf '# the dated mirror\n\n  1bit/hrx-vulkan-20261110  \n1bit/ignored-second-line\n' > "$mb"
+expect "the first line that is not a comment names the mirror, spaces around it ignored" "$(branch)" "1bit/hrx-vulkan-20261110"
+for bad in '1bit/hrx-vulkan-patched' 'refs/heads/1bit/x' '../x' '-x' 'a b' 'x;rm' 'x:y'; do
+  printf '%s\n' "$bad" > "$mb"
+  if out=$(branch); then fail "a mirror named '$bad' is refused (got: $out)"; else
+    case "$out" in *"$mb"*|*llama-mirror*|*mirror*) ok "a mirror named '$bad' is refused, naming the file" ;; *) fail "the refusal of '$bad' names the file (got: $out)" ;; esac
+  fi
+done
+# The same refusal through the path the workflow runs: `llama` reads the name inside a command substitution, where a
+# message written to stdout is captured into the variable and never printed. The run must fail AND say why.
+printf 'x;rm\n' > "$mb"
+mkdir -p "$work/empty-scratch"
+if out=$(cd "$work/empty-scratch" && env -u GH_TOKEN -u GITHUB_TOKEN DRY_RUN=1 LLAMA_MIRROR_FILE=$mb AMD_LLAMA=$(printf "a%.0s" $(seq 40)) OURS_HRX=$(printf "b%.0s" $(seq 40)) bash "$script" llama 2>&1); then
+  fail "the llama sync with a mirror named 'x;rm' fails (it exited 0: $out)"
+else
+  case "$out" in
+    *"::error::"*"not a plain branch name"*) ok "the llama sync refuses a bad mirror name with its ::error:: line, not silently" ;;
+    *) fail "the llama sync's refusal of a bad mirror name is printed (got: '$out')" ;;
+  esac
+fi
+shipped_mb=$(cd "$(dirname "$script")/.." && pwd)/config/llama-mirror-branch.config
+if [ -f "$shipped_mb" ]; then
+  expect "the shipped file names no branch, so the mirror is unchanged" "$(LLAMA_MIRROR_FILE=$shipped_mb bash "$script" mirror-branch)" "1bit/hrx-vulkan"
+else
+  fail "config/llama-mirror-branch.config is in the tree"
+fi
+
 if [ "$fails" -ne 0 ]; then echo "$fails check(s) failed"; exit 1; fi
 echo "bump_hrx_sync: ok"