diff --git a/docs/reference.md b/docs/reference.md
index e84b47c..7a69a46 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -263,7 +263,7 @@ Your hands show over the screens: where a tracked hand is between an eye and a s
 - `ft-camd` borrows XRService's camera buffers and publishes the four IR tracking cameras to `/run/user/UID/frametop-hands/cam-ring`. It runs on the host as `frametop-camd.service`, with file capabilities that `hands/run.sh install` sets through sudo, and it drops them once set up. A rebuild clears them: `hands/run.sh caps`.
 - `ft-hands` runs in the `dev` container as `frametop-hands.service`. It finds and triangulates the hands, and publishes `hands` (read by ft-screens' cutouts) and `gestures` (pinches and grips, read by the pointer helper) next to the ring.
 - The install leaves both off, and they don't start with SteamVR. `ft-handsctl on` starts them while SteamVR runs, and `ft-handsctl off` stops them; they also stop with SteamVR. The install links `ft-handsctl` into `~/.local/bin`. `ft-handsctl status` and `ft-handsctl log` (or `hands/run.sh status` and `log`) show how they're doing, `ft-handsctl cutouts on|off` turns just the cutouts off, and `ft-handsctl gestures` shows pinches and grips live.
-- Settings in `~/.config/frametop.conf`: `HANDS_SWAP_SIDES` (after some SteamVR restarts the side cameras' names come out swapped, and hands land beside the holes; `hands/tools/check_sides.py --ring` tells), `HANDS_CPUS`, the cameras it tracks with (`HANDS_CAMERAS`, `HANDS_BRIGHT`, `HANDS_BRIGHT_ON`, `HANDS_BRIGHT_OFF`, `HANDS_COLOR_LEFT`, `HANDS_COLOR_CROP`), and the pointer helper's `POINTER_HANDS`, `POINTER_PINCH_GAIN`, `POINTER_PINCH_DEADZONE`, `POINTER_GRIP_GAIN`, `POINTER_GRIP_BELOW`, and `POINTER_PINCH_TYPING`. The example config explains each.
+- Settings in `~/.config/frametop.conf`: `HANDS_SWAP_SIDES` (`auto`, the default: ft-hands tells from the hands when some SteamVR restart has swapped the side cameras' names, and fixes them; `0` or `1` force them, and `hands/tools/check_sides.py --ring` tells which is right), `HANDS_CPUS`, the cameras it tracks with (`HANDS_CAMERAS`, `HANDS_BRIGHT`, `HANDS_BRIGHT_ON`, `HANDS_BRIGHT_OFF`, `HANDS_COLOR_LEFT`, `HANDS_COLOR_CROP`), and the pointer helper's `POINTER_HANDS`, `POINTER_PINCH_GAIN`, `POINTER_PINCH_DEADZONE`, `POINTER_GRIP_GAIN`, `POINTER_GRIP_BELOW`, and `POINTER_PINCH_TYPING`. The example config explains each.
 
 Details, options, and the recording and replay tools are in [hands/README.md](../hands/README.md).
 
diff --git a/hands/README.md b/hands/README.md
index 5b84901..fd6a9bc 100644
--- a/hands/README.md
+++ b/hands/README.md
@@ -36,7 +36,7 @@ hands/run.sh uninstall
 
 Settings in `~/.config/frametop.conf` (`FT_<name>` in the environment overrides them), read when ft-camd and ft-hands start:
 
-- `HANDS_SWAP_SIDES=auto` (the default): ft-hands tells from the hands which side camera is which, and corrects ft-camd's names when they're backwards (see "Which camera is which" below). `1` forces them exchanged and `0` forces ft-camd's names; ft-hands still checks and logs a warning if the hands disagree.
+- `HANDS_SWAP_SIDES=auto` (the default): ft-hands tells from the hands which side camera is which, and corrects ft-camd's names when they're backwards (see "Which camera is which" below). `1` forces them exchanged and `0` forces ft-camd's names; ft-hands still checks, and if the hands disagree it logs a warning and publishes the hands' answer as the truth (`sides.json`), so recordings are labelled right. The example config said `0` until 2026-10-05; `scripts/conf-migrate.sh` (run by `install.sh` and `hands/rec/install.sh`) turns that untouched line into `auto`.
 - `HANDS_CPUS=5,6,7`: the CPUs the model threads run on (below).
 - `HANDS_CAMERAS` (`auto`), `HANDS_BRIGHT` (`all`), `HANDS_BRIGHT_ON` (40), `HANDS_BRIGHT_OFF` (25): which cameras ft-hands tracks with, as `--cams`, `--bright`, `--bright-on` and `--bright-off` (see ft-hands). `HANDS_CAMERAS=mono` also keeps ft-camd off the colour cameras.
 - `HANDS_COLOR_LEFT` (`color_video0`), `HANDS_COLOR_CROP` (`subtract`): how the colour module's calibration maps onto its images, as `--color-left` and `--color-crop`.
diff --git a/hands/rec/install.sh b/hands/rec/install.sh
index 92a1c0d..22da7be 100755
--- a/hands/rec/install.sh
+++ b/hands/rec/install.sh
@@ -23,6 +23,7 @@ case ${1:-install} in
     "$root/hands/rec/build.sh"
     echo "== 4/4 ft-camd's capabilities (asks for your password) and the menu entry"
     "$root/hands/run.sh" caps
+    "$root/scripts/conf-migrate.sh"   # HANDS_SWAP_SIDES=0, the old default, becomes auto
     fill_template "$root/hands/rec/ft-handrec.desktop" |
       on_frame "mkdir -p ~/.local/share/applications && cat > $entry"
     echo
diff --git a/install.sh b/install.sh
index 9c0775e..eb04347 100755
--- a/install.sh
+++ b/install.sh
@@ -93,6 +93,7 @@ step "7/10 multi-screen desktop (ft-screens), Frametop Input Settings, and Frame
 "$root/remote/install.sh"
 on_frame "sed -i 's/^POINTER=0/POINTER=1/' ~/.config/frametop.conf; grep -q '^POINTER=' ~/.config/frametop.conf || echo 'POINTER=1' >> ~/.config/frametop.conf"
 echo "the launcher's Desktop entry now opens the multi-screen desktop; 3D mouse on (POINTER=1 in ~/.config/frametop.conf)"
+"$root/scripts/conf-migrate.sh"
 
 step "8/10 gaze mode (optional, experimental: the pointer goes where you look)"
 gaze=0
diff --git a/scripts/conf-migrate.sh b/scripts/conf-migrate.sh
new file mode 100755
index 0000000..b1d4acc
--- /dev/null
+++ b/scripts/conf-migrate.sh
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# Update the lines of ~/.config/frametop.conf that still read exactly as an older
+# frametop.conf.example wrote them. A line you changed stays as it is. install.sh and
+# hands/rec/install.sh run this on every install and update.
+#   HANDS_SWAP_SIDES=0: the example's value until 2026-10-05. It made ft-hands keep ft-camd's side
+#   camera names even when they're backwards (some SteamVR restarts swap them), so hands landed
+#   beside their cutouts and the hand recorder labelled the side cameras wrong. auto tells from
+#   the hands.
+set -euo pipefail
+root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+. "$root/scripts/_env.sh"
+
+on_frame_script <<'EOF'
+f=~/.config/frametop.conf
+[ -f "$f" ] || exit 0
+old="HANDS_SWAP_SIDES=0         # hand tracking (hands/run.sh install): 1 = the side cameras' names are swapped, which some SteamVR restarts cause (hands/tools/check_sides.py --ring tells)"
+new="HANDS_SWAP_SIDES=auto      # hand tracking: which side camera is which. auto = ft-hands tells from the hands and fixes ft-camd's names, which some SteamVR restarts swap | 0 = keep ft-camd's | 1 = exchange them"
+if grep -qxF "$old" "$f"; then
+  tmp=$(mktemp)
+  awk -v old="$old" -v new="$new" '$0 == old { print new; next } { print }' "$f" > "$tmp"
+  cat "$tmp" > "$f"   # in place: the file keeps its owner and mode
+  rm -f "$tmp"
+  echo "settings: HANDS_SWAP_SIDES=0 (the old default) is now auto: hand tracking tells the side cameras apart itself"
+fi
+EOF
diff --git a/session/frametop.conf.example b/session/frametop.conf.example
index 1886482..4250a0d 100644
--- a/session/frametop.conf.example
+++ b/session/frametop.conf.example
@@ -40,7 +40,7 @@ POINTER_HEAD_DEADZONE=0.5  # keyboard clicks at the gaze (Meta+J, Meta+K): degre
 POINTER_KEY_TAP=0.25       # keyboard clicks: let go within this (s) and it clicks where the dot was at the press, and tells the gaze tracker it was right
 GAZE_TRACKER=auto          # gaze service: auto = our own eye tracker when it's installed (gaze/tracker/install.sh, which install.sh offers), else SteamVR's | own = ours | steam = SteamVR's. Each keeps its own calibration (Calibrate on Frametop Input Settings' Gaze page)
 GAZE_EYE=auto              # gaze service: eye bias. auto = each eye weighted by how far off it was at your recent nudges | left | right = that eye counts twice
-HANDS_SWAP_SIDES=0         # hand tracking (hands/run.sh install): 1 = the side cameras' names are swapped, which some SteamVR restarts cause (hands/tools/check_sides.py --ring tells)
+HANDS_SWAP_SIDES=auto      # hand tracking: which side camera is which. auto = ft-hands tells from the hands and fixes ft-camd's names, which some SteamVR restarts swap | 0 = keep ft-camd's | 1 = exchange them
 HANDS_CPUS=5,6,7           # hand tracking: the CPUs its model threads run on
 HANDS_CAMERAS=auto         # hand tracking: auto (by the light) | mono (the IR cameras; also keeps ft-camd off the colour ones) | color | all
 HANDS_BRIGHT=all           # hand tracking, auto: the cameras in bright light, all | color