diff --git a/deploy/deploy-dev.sh b/deploy/deploy-dev.sh
new file mode 100755
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--- /dev/null
+++ b/deploy/deploy-dev.sh
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+#!/usr/bin/env bash
+# LAN-dev deploy: roll the per-service registry-pull stack (see deploy.sh) onto
+# the ~/thermograph-dev overlay instead of prod/beta's loopback-only stack.
+#
+# *** PREREQUISITE -- READ BEFORE RUNNING ***
+# This script assumes $APP_DIR is a checkout of THIS repo (thermograph-infra),
+# the same way /opt/thermograph is on prod/beta. As of this writing, the LAN
+# dev box's ~/thermograph-dev is still provisioned by deploy/provision-dev-lan.sh
+# cloning the OLD MONOREPO (thermograph.git, see its REPO_URL default) and running
+# the monorepo's build-in-place deploy/deploy-dev.sh -- an app-code checkout with
+# Dockerfiles, not an infra checkout with compose files. Until provision-dev-lan.sh
+# (and its REPO_URL) is repointed at thermograph-infra and ~/thermograph-dev is
+# reprovisioned from that, THIS SCRIPT IS INERT: pointing it at the live dev box
+# today would `git fetch`/`reset` the wrong repository entirely. Do not treat this
+# as a live deploy path until that reprovision happens -- it exists now so the infra
+# repo carries its own dev-deploy story from day one, same as it already carries
+# deploy.sh for prod/beta.
+#
+# Design: a thin wrapper around deploy.sh, not a duplicate. deploy.sh already owns
+# the entire per-service registry-pull mechanism -- secrets sourcing, docker login,
+# the retry-pull loop, --no-deps single-service rolls vs. --remove-orphans `all`,
+# .image-tags.env persistence, and the 8137/8080 health checks. None of that is
+# dev-specific; the only things LAN dev actually changes are WHERE it deploys
+# (a separate checkout + branch) and WHICH compose files are in play (the base
+# file plus docker-compose.dev.yml's uncapped/LAN-published overrides). Both are
+# expressible as environment (APP_DIR/BRANCH that deploy.sh already reads, and
+# docker compose's own COMPOSE_FILE variable), so re-exec'ing deploy.sh with that
+# environment set covers it with no forked copy of the pull/roll/health logic to
+# drift out of sync. If LAN dev ever needs deploy logic that genuinely diverges
+# from prod/beta (not just "different files/directory"), promote this to a
+# standalone script at that point rather than growing special cases into deploy.sh.
+#
+# Usage (once the prerequisite above is satisfied), mirrors deploy.sh directly:
+#   # roll just the backend onto a dev-tagged image:
+#   ssh dev-box 'SERVICE=backend BACKEND_IMAGE_TAG=sha-<12hex> deploy/deploy-dev.sh'
+#   # bring the whole dev stack up (both tags required, same as deploy.sh):
+#   ssh dev-box 'SERVICE=all BACKEND_IMAGE_TAG=sha-<a> FRONTEND_IMAGE_TAG=sha-<b> deploy/deploy-dev.sh'
+set -euo pipefail
+
+# Dev context: a separate checkout + branch from prod/beta's /opt/thermograph
+# (main), so a dev deploy never touches or is touched by the prod/beta one.
+APP_DIR="${APP_DIR:-$HOME/thermograph-dev}"
+BRANCH="${BRANCH:-dev}"
+export APP_DIR BRANCH
+
+# Point every `docker compose` invocation inside deploy.sh at the LAN-dev overlay
+# (uncapped CPU, backend published on 0.0.0.0:8137, frontend unpublished -- see
+# docker-compose.dev.yml) without deploy.sh needing to know dev exists at all.
+# COMPOSE_FILE is docker compose's own env var for this; ':' is the Linux/macOS
+# path-list separator it expects (';' only on Windows).
+export COMPOSE_FILE="docker-compose.yml:docker-compose.dev.yml"
+
+# deploy.sh needs POSTGRES_PASSWORD to interpolate the compose file (both to init
+# the db container and to build backend's THERMOGRAPH_DATABASE_URL) -- normally
+# supplied by /etc/thermograph.env via render-secrets.sh's SOPS render, but dev has
+# no entry in deploy/secrets/ (only common/beta/prod.yaml exist), so
+# render_thermograph_secrets degrades to a no-op here (see render-secrets.sh) and
+# /etc/thermograph.env likely doesn't exist on a fresh dev box either. Postgres is
+# loopback-only inside the compose network on dev (never published, no real
+# credentials on this box), so a fixed default is fine -- same value the monorepo's
+# deploy-dev.sh used historically. Override via the environment if you ever want a
+# different one; this only sets it when nothing else already has.
+export POSTGRES_PASSWORD="${POSTGRES_PASSWORD:-thermograph-dev}"
+
+# REGISTRY_TOKEN (for `docker login` in deploy.sh) is a REAL credential -- read
+# access to git.thermograph.org's registry -- and deliberately has NO default here.
+# Until dev gets its own deploy/secrets/dev.yaml entry (see deploy/secrets/README.md)
+# it must come from the calling environment: exported by hand for a manual run, or
+# injected by whatever eventually SSHes in to trigger a dev deploy (analogous to
+# how deploy.yml supplies it for prod/beta today). deploy.sh's own `docker login`
+# step fails loudly if it's unset or wrong -- nothing silently no-ops.
+
+echo "==> LAN-dev deploy: APP_DIR=$APP_DIR BRANCH=$BRANCH COMPOSE_FILE=$COMPOSE_FILE"
+exec "$(dirname "$0")/deploy.sh" "$@"
diff --git a/docker-compose.dev.yml b/docker-compose.dev.yml
new file mode 100644
index 0000000..c2107fd
--- /dev/null
+++ b/docker-compose.dev.yml
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+# Dev overlay for the LAN dev server (deploy/deploy-dev.sh):
+#
+#   docker compose -f docker-compose.yml -f docker-compose.dev.yml up -d
+#
+# Split-repo adaptation: the monorepo's docker-compose.dev.yml (see
+# thermograph/docker-compose.dev.yml) overlaid a base file where backend and
+# frontend had `build: .` -- dev's whole point there was `--build` in place from
+# the working checkout. This infra repo holds no Dockerfile at all (each service's
+# lives in its own app repo, thermograph-backend / thermograph-frontend), so the
+# base docker-compose.yml already has NO `build:` for either service, only
+# `image: .../${BACKEND_IMAGE_PATH}:${BACKEND_IMAGE_TAG}` (and the frontend
+# equivalent) -- same registry-pull model as prod/beta, just pointed at a dev tag
+# by deploy-dev.sh. This overlay must NOT reintroduce `build:`; it only relaxes
+# resource caps and LAN-exposes a port, same as the monorepo overlay did.
+#
+# Differences from the prod stack (unchanged intent from the monorepo overlay):
+#  1. backend is published on ALL interfaces (0.0.0.0:8137), not loopback, so
+#     phones and other devices on the Wi-Fi can reach the dev server directly --
+#     dev has no Caddy in front (prod does, which is why the base file binds
+#     127.0.0.1 only).
+#  2. frontend's port publish is dropped entirely -- dev has no Caddy to reach it
+#     directly, so it stays compose-internal-only, reached solely through
+#     backend's own reverse-proxy fallback (THERMOGRAPH_FRONTEND_BASE_INTERNAL,
+#     see backend/web/app.py's _proxy_to_frontend in the backend repo). This
+#     keeps the dev stack serving the one URL it always has, at :8137.
+#  3. The CPU caps are removed -- dev runs UNCAPPED (no thread/CPU limits), unlike
+#     prod's backend=4 / frontend=2 / db=2 allocation. `!reset` drops the base
+#     value (both the top-level `cpus:` and the Swarm-style `deploy.resources`
+#     block the base file carries for parity).
+services:
+  backend:
+    ports: !override
+      - "8137:8137"
+    cpus: !reset null
+    deploy: !reset null
+  frontend:
+    ports: !reset null
+    cpus: !reset null
+    deploy: !reset null
+  db:
+    cpus: !reset null
+    deploy: !reset null
+    # Uncapped memory on dev too (prod ceilings it at 8g). The Postgres/DuckDB
+    # memory *budget* is still the ~8 GB derived by deploy/db/init/20-tuning.sh from
+    # the default DB_MEMORY (raise DB_MEMORY to give dev more); shm_size stays (it's
+    # required shared memory for parallel query, not a limit).
+    mem_limit: !reset null