diff --git a/deploy/fleet/deploy_supervisor_step_test.py b/deploy/fleet/deploy_supervisor_step_test.py
new file mode 100755
index 000000000..ef20c9f8f
--- /dev/null
+++ b/deploy/fleet/deploy_supervisor_step_test.py
@@ -0,0 +1,210 @@
+#!/usr/bin/env python3
+"""install.sh installs the deploy supervisor on a checkout install, with the timer OFF.
+
+Runs install.sh's own step_deploy_supervisor, extracted from the script, in a temporary HOME
+with `git`, `cargo`, `systemctl` and `uname` replaced by stubs. No network, no real install.
+The stub systemctl records every call, so "the timer stays off" is checked as "nothing asked
+systemd to enable it", not inferred from a missing file.
+"""
+import os
+import pathlib
+import re
+import subprocess
+import tempfile
+
+HERE = pathlib.Path(__file__).resolve().parent
+SCRIPT = (HERE / "install.sh").read_text()
+FAILS = []
+
+
+def check(name, ok, detail=""):
+    print(("PASS " if ok else "FAIL ") + name + ("" if ok else f" -- {detail}"))
+    if not ok:
+        FAILS.append(name)
+
+
+def func(name):
+    m = (re.search(rf"^{name}\(\) \{{\n.*?^\}}\n", SCRIPT, re.S | re.M)
+         or re.search(rf"^{name}\(\)\s+\{{[^\n]*\}}\n", SCRIPT, re.M))  # one-line form
+    assert m, name
+    return m.group(0)
+
+
+BODY = "\n".join(func(n) for n in ("c_dim", "c_ok", "c_warn", "c_err", "c_hdr",
+                                   "systemd_env_line", "step_deploy_supervisor"))
+
+# The REAL shipped files, so the HESTIA_WORKSPACE substitution is tested against the unit that
+# actually ships, not a copy of what it looked like when this test was written.
+FROM_MAIN = HERE.parent / "from-main"
+assert "\nEnvironment=HESTIA_WORKSPACE=\n" in (FROM_MAIN / "hestia-deploy.service").read_text(), \
+    "hestia-deploy.service no longer ships an empty HESTIA_WORKSPACE= line; update install.sh's sed"
+
+
+def stub(d, name, body):
+    p = d / name
+    p.write_text("#!/bin/sh\n" + body)
+    p.chmod(0o755)
+
+
+def systemd_environment(unit_text):
+    """The variables systemd would set from a unit's Environment= lines.
+
+    A small model of systemd's parser for this one directive (extract_first_word with
+    EXTRACT_UNQUOTE|EXTRACT_CUNESCAPE, then specifier expansion): words split at unquoted
+    whitespace, double quotes group, backslash escapes inside quotes, `%%` is a literal `%`.
+    A word without `=` is dropped, as systemd drops it ("Invalid environment assignment").
+    """
+    env = {}
+    for line in unit_text.splitlines():
+        if not line.startswith("Environment="):
+            continue
+        rest, words, cur, quoted, i, inword = line[len("Environment="):], [], "", False, 0, False
+        while i < len(rest):
+            c = rest[i]
+            if quoted:
+                if c == "\\" and i + 1 < len(rest):
+                    cur += rest[i + 1]
+                    i += 1
+                elif c == '"':
+                    quoted = False
+                else:
+                    cur += c
+            elif c == '"':
+                quoted, inword = True, True
+            elif c.isspace():
+                if inword:
+                    words.append(cur)
+                cur, inword = "", False
+            else:
+                cur, inword = cur + c, True
+            i += 1
+        if inword:
+            words.append(cur)
+        for w in words:
+            w = w.replace("%%", "\0").replace("\0", "%")
+            if "=" in w:
+                k, v = w.split("=", 1)
+                env[k] = v
+    return env
+
+
+def run(*, workspace="ws", cargo=True, os_name="Linux", env_extra=None, timer_enabled=False):
+    with tempfile.TemporaryDirectory() as t:
+        t = pathlib.Path(t)
+        home, bin_stubs = t / "home", t / "stubs"
+        home.mkdir()
+        bin_stubs.mkdir()
+        calls = t / "systemctl.log"
+        # git clone <url> <dest>: lay down the deploy/from-main files a real clone would carry.
+        stub(bin_stubs, "git", f"""dest="$4"
+mkdir -p "$dest/.git" "$dest/deploy/from-main"
+cp "{FROM_MAIN}/hestia-deploy.sh" "{FROM_MAIN}/hestia-deploy.service" "{FROM_MAIN}/hestia-deploy.timer" "$dest/deploy/from-main/"
+""")
+        if cargo:
+            stub(bin_stubs, "cargo", "exit 0\n")
+        stub(bin_stubs, "systemctl", f"""echo "$*" >> "{calls}"
+case "$*" in *is-enabled*) [ "{int(timer_enabled)}" = 1 ] && exit 0 || exit 1 ;; esac
+exit 0
+""")
+        stub(bin_stubs, "uname", f"echo {os_name}\n")
+        ws = ""
+        if workspace:
+            ws = str(t / workspace)
+            os.makedirs(ws)
+        # systemd-analyze, when present, is the real parser; keep it on PATH.
+        env = {
+            "PATH": f"{bin_stubs}:/usr/bin:/bin",  # /usr/bin keeps systemd-analyze when installed
+            "HOME": str(home),
+            "HESTIA_HOME": str(home / ".hestia"),
+            "HESTIA_HOME_DEFAULT": str(home / ".hestia"),
+            "HESTIA_WORKSPACE": ws,
+            "BIN_DIR": str(home / ".local/bin"),
+        }
+        env.update(env_extra or {})
+        script = "set -euo pipefail\n" + BODY + "\nstep_deploy_supervisor\n"
+        r = subprocess.run(["bash", "-c", script], env=env, capture_output=True, text=True)
+        unit = home / ".config/systemd/user/hestia-deploy.service"
+        return {
+            "rc": r.returncode,
+            "out": r.stdout + r.stderr,
+            "calls": calls.read_text().splitlines() if calls.exists() else [],
+            "unit": unit.read_text() if unit.exists() else None,
+            "timer": (home / ".config/systemd/user/hestia-deploy.timer").exists(),
+            "script": (home / ".local/bin/hestia-deploy").exists(),
+            "ws": ws,
+        }
+
+
+# 1. A checkout install gets a working update button, and the schedule stays off.
+r = run()
+check("checkout install exits 0", r["rc"] == 0, r["out"])
+check("hestia-deploy script installed", r["script"], r["out"])
+check("service unit installed", r["unit"] is not None, r["out"])
+check("timer unit installed", r["timer"], r["out"])
+check("HESTIA_WORKSPACE rendered into the unit",
+      r["unit"] is not None and systemd_environment(r["unit"]).get("HESTIA_WORKSPACE") == r["ws"],
+      r["unit"])
+check("units reloaded", "--user daemon-reload" in r["calls"], r["calls"])
+check("timer NOT enabled by default", not any("enable" in c and "is-enabled" not in c for c in r["calls"]),
+      r["calls"])
+check("says auto-update is off", "auto-update OFF" in r["out"], r["out"])
+
+# 2. Opt-in arms the timer.
+r = run(env_extra={"HESTIA_AUTO_UPDATE": "1"})
+check("HESTIA_AUTO_UPDATE=1 enables the timer",
+      "--user enable --now hestia-deploy.timer" in r["calls"], r["calls"])
+
+# 3. A re-run on a box whose timer is already on leaves it on.
+r = run(timer_enabled=True)
+check("armed timer is left armed", not any("disable" in c for c in r["calls"]), r["calls"])
+check("says it left it on", "already ON" in r["out"], r["out"])
+
+# 4. Release install (no checkout): skipped with the reason, nothing written.
+r = run(workspace="")
+check("release install skips", r["rc"] == 0 and r["unit"] is None and not r["script"], r["out"])
+check("release install says why", "release install" in r["out"], r["out"])
+
+# 5. No cargo: skipped with the reason, nothing written.
+r = run(cargo=False)
+check("missing cargo skips", r["rc"] == 0 and r["unit"] is None, r["out"])
+check("missing cargo is named", "needs cargo" in r["out"], r["out"])
+
+# 6. Explicit opt-out, and macOS (not automated yet).
+r = run(env_extra={"HESTIA_SKIP_DEPLOY": "1"})
+check("HESTIA_SKIP_DEPLOY skips", r["unit"] is None and r["calls"] == [], r["out"])
+r = run(os_name="Darwin")
+check("macOS points at the README", r["unit"] is None and "README" in r["out"], r["out"])
+
+# 7. A workspace path systemd would split or misread: spaces, quote, backslash, %, and sed's
+#    own metacharacters. Each must reach the unit as the same string systemd will parse back.
+for name in ("My Projects", 'a "q" b', "back\\slash", "100% ws", "pipe|amp&x", "x=y z"):
+    r = run(workspace=name)
+    got = systemd_environment(r["unit"] or "").get("HESTIA_WORKSPACE")
+    check(f"workspace {name!r} survives systemd parsing", r["rc"] == 0 and got == r["ws"],
+          f"rc={r['rc']} got={got!r} want={r['ws']!r}\n{r['out']}")
+    check(f"workspace {name!r} adds no stray variable",
+          set(systemd_environment(r["unit"] or "")) <= {"HESTIA_HOME", "HESTIA_WORKSPACE", "PATH"},
+          r["unit"])
+
+# 8. A non-default HESTIA_HOME: the units run against ~/.hestia, so the step refuses to
+#    install a supervisor that would clone into one home and deploy into another.
+r = run(env_extra={"HESTIA_HOME": "/srv/elsewhere/hestia"})
+check("non-default HESTIA_HOME skips", r["rc"] == 0 and r["unit"] is None and not r["script"]
+      and r["calls"] == [], r["out"])
+check("non-default HESTIA_HOME says why", str(pathlib.Path("home")) in r["out"] and "/srv/elsewhere/hestia" in r["out"],
+      r["out"])
+
+# 9. The model above agrees with systemd where systemd is installed.
+import shutil  # noqa: E402
+if shutil.which("systemd-analyze"):
+    r = run(workspace="My Projects 100%")
+    with tempfile.TemporaryDirectory() as t:
+        u = pathlib.Path(t) / "hestia-deploy.service"
+        u.write_text(r["unit"] or "")
+        v = subprocess.run(["systemd-analyze", "verify", str(u)], capture_output=True, text=True)
+    check("systemd-analyze parses the rendered Environment= lines without complaint",
+          r["rc"] == 0 and "environment" not in (v.stdout + v.stderr).lower(), v.stdout + v.stderr)
+
+if FAILS:
+    raise SystemExit(f"{len(FAILS)} check(s) failed: " + ", ".join(FAILS))
+print("deploy supervisor install step: PASS")
diff --git a/deploy/fleet/install.sh b/deploy/fleet/install.sh
index 60aa64260..ca4b30d2b 100755
--- a/deploy/fleet/install.sh
+++ b/deploy/fleet/install.sh
@@ -19,6 +19,8 @@
 #   HESTIA_HOME      override install location for state (default: ~/.hestia)
 #   HESTIA_BIND      bind address for the daemon (default: 127.0.0.1:7711)
 #   HESTIA_SKIP_HOOK if set, do NOT wire ~/.claude/settings.json hooks
+#   HESTIA_SKIP_DEPLOY   if set, do NOT install the deploy supervisor (dashboard update button)
+#   HESTIA_AUTO_UPDATE   =1 also arms the 4-hourly deploy timer (default: installed but OFF)
 #
 set -euo pipefail
 
@@ -29,7 +31,9 @@ REPO="dp-web4/hestia"
 # falls back to this floor only when the API cannot be reached (offline, rate-limited).
 FALLBACK_VERSION="v0.0.4"
 VERSION="${HESTIA_VERSION:-}"
-HESTIA_HOME="${HESTIA_HOME:-$HOME/.hestia}"
+# The default home, named once: the deploy units are bound to it (step_deploy_supervisor).
+HESTIA_HOME_DEFAULT="$HOME/.hestia"
+HESTIA_HOME="${HESTIA_HOME:-$HESTIA_HOME_DEFAULT}"
 HESTIA_BIND="${HESTIA_BIND:-127.0.0.1:7711}"
 # DERIVE, do not enumerate. The first draft of this block listed the workspace roots of
 # the machines in this fleet, which is wrong twice: it is a guess on any machine not on
@@ -789,6 +793,139 @@ step_workspace_marker() {
   fi
 }
 
+# The deploy supervisor (deploy/from-main): what the dashboard's update / "check for updates"
+# button starts, and what its auto-update toggle schedules.
+#
+# WHY HERE. Until this step the supervisor was a separate once-per-box install in
+# deploy/from-main/README.md that no installer ran, so on every box set up from this script the
+# dashboard offered an update button that could only fail with "Unit hestia-deploy.service not
+# found" (#791, Nomad 2026-09-01; tl-dell 2026-10-16). An operator should not need a README of
+# shell lines to get a working update button.
+#
+# WHAT IT INSTALLS, AND WHAT IT LEAVES OFF. The two deploy clones under $HESTIA_HOME/deploy, the
+# hestia-deploy script, and the service + timer units, with HESTIA_WORKSPACE rendered. The
+# TIMER STAYS OFF unless HESTIA_AUTO_UPDATE=1: nothing builds or restarts until the operator
+# clicks update or switches auto-update on in the dashboard. A re-run never turns an armed
+# timer off and never touches the deploy clones' history.
+#
+# WHEN IT SKIPS (and says so). The supervisor builds hestia main from source, so it needs a
+# checkout install (a resolved HESTIA_WORKSPACE) with git and cargo. A release install
+# (`curl | sh`) tracks releases, not main, and is updated by re-running this script; converting
+# it to main-tracking is a choice this step does not make for it. macOS: the launchd agent's
+# binary path must be derived from the daemon's registration (README), so it is not automated
+# here yet.
+# One systemd `Environment=` line for VAR=VALUE that survives systemd's own parser. Unquoted,
+# the value is split at whitespace (a workspace under "/home/x/My Projects" became two
+# assignments, one of them invalid and dropped: measured with systemd-analyze verify), `%` is
+# a specifier, and backslash and quote are special. So: double-quote the whole assignment,
+# escape backslash and quote, and double every `%` (systemd.exec(5), systemd.unit(5)
+# "Specifiers"). A newline cannot be expressed in a unit file at all: refuse it.
+systemd_env_line() {
+  local var="$1" val="$2" nl=$'\n'
+  case "$val" in *"$nl"*) return 1 ;; esac
+  val="${val//\\/\\\\}"
+  val="${val//\"/\\\"}"
+  val="${val//%/%%}"
+  printf 'Environment="%s=%s"\n' "$var" "$val"
+}
+
+step_deploy_supervisor() {
+  if [ -n "${HESTIA_SKIP_DEPLOY:-}" ]; then
+    c_dim "deploy supervisor skipped (HESTIA_SKIP_DEPLOY set)"
+    return
+  fi
+  c_hdr "deploy supervisor (dashboard update button)"
+  if [ "$(uname -s)" != Linux ]; then
+    c_dim "not automated on $(uname -s) yet: see deploy/from-main/README.md (launchd)"
+    return
+  fi
+  if [ -z "${HESTIA_WORKSPACE:-}" ]; then
+    c_dim "release install (no checkout): update by re-running this installer."
+    c_dim "  the deploy supervisor builds hestia main from source; to opt in, run this script"
+    c_dim "  from a checkout, or see deploy/from-main/README.md"
+    return
+  fi
+  # The shipped units are bound to ~/.hestia (HESTIA_HOME=%h/.hestia here, and the same in the
+  # daemon unit this script installs), and hestia-deploy defaults its clones to
+  # ~/.hestia/deploy. Installing for another HESTIA_HOME would put the clones where the
+  # supervisor never looks and deploy into a home the daemon does not read. Until the units
+  # take HESTIA_HOME from configuration, say so instead of installing a half-wired supervisor.
+  if [ "$HESTIA_HOME" != "${HESTIA_HOME_DEFAULT:?}" ]; then
+    c_warn "deploy supervisor not installed: HESTIA_HOME is $HESTIA_HOME, but the deploy units"
+    c_warn "  run against $HESTIA_HOME_DEFAULT. Install it by hand (deploy/from-main/README.md) if this box"
+    c_warn "  should deploy from main, with HESTIA_HOME and HESTIA_DEPLOY_ROOT set in the unit."
+    return
+  fi
+  local missing=""
+  command -v git >/dev/null 2>&1   || missing="$missing git"
+  command -v cargo >/dev/null 2>&1 || missing="$missing cargo"
+  if [ -n "$missing" ]; then
+    c_warn "deploy supervisor not installed: needs$missing (it builds hestia main from source)"
+    c_warn "  install the missing tool(s) and re-run this installer"
+    return
+  fi
+  local deploy_root="$HESTIA_HOME/deploy" unit_dir="$HOME/.config/systemd/user"
+  local src="$deploy_root/hestia/deploy/from-main"
+  mkdir -p "$deploy_root" "$unit_dir" "$BIN_DIR"
+  # https, not ssh: the units run without an agent or a key, and both repos are public.
+  local name
+  for name in hestia web4; do
+    if [ ! -d "$deploy_root/$name/.git" ]; then
+      git clone -q "https://github.com/dp-web4/$name.git" "$deploy_root/$name" \
+        || { c_err "clone of $name into $deploy_root failed"; return 1; }
+    fi
+  done
+  if [ ! -f "$src/hestia-deploy.sh" ]; then
+    c_err "deploy checkout has no deploy/from-main/hestia-deploy.sh: $deploy_root/hestia"
+    return 1
+  fi
+  install -m 0755 "$src/hestia-deploy.sh" "$BIN_DIR/hestia-deploy"
+  # The shipped unit leaves HESTIA_WORKSPACE empty on purpose ("render it from explicit operator
+  # configuration"); this installer's resolved workspace is that configuration. The line is
+  # replaced by awk reading it from the environment, not by sed: a workspace path containing
+  # `|`, `&` or `\` would otherwise be read as sed syntax.
+  local env_line
+  if ! env_line="$(systemd_env_line HESTIA_WORKSPACE "$HESTIA_WORKSPACE")"; then
+    c_err "HESTIA_WORKSPACE contains a newline; a systemd unit cannot carry it"
+    return 1
+  fi
+  if ! ENV_LINE="$env_line" awk '
+      $0 == "Environment=HESTIA_WORKSPACE=" { print ENVIRON["ENV_LINE"]; n++; next }
+      { print }
+      END { exit n == 1 ? 0 : 1 }' \
+      "$src/hestia-deploy.service" > "$unit_dir/hestia-deploy.service"; then
+    c_err "hestia-deploy.service no longer has exactly one empty HESTIA_WORKSPACE= line: $src"
+    return 1
+  fi
+  install -m 0644 "$src/hestia-deploy.timer" "$unit_dir/hestia-deploy.timer"
+  # Read back, as the other steps do: a zero exit is not evidence the bytes landed.
+  if ! grep -qxF -- "$env_line" "$unit_dir/hestia-deploy.service"; then
+    c_err "hestia-deploy.service was written without HESTIA_WORKSPACE: $unit_dir/hestia-deploy.service"
+    return 1
+  fi
+  # And have systemd itself parse it, where it can: an assignment it splits or rejects is a
+  # warning on stderr with exit 0, so the warning is what is checked.
+  if command -v systemd-analyze >/dev/null 2>&1; then
+    local verify
+    verify="$(systemd-analyze verify "$unit_dir/hestia-deploy.service" 2>&1 || true)"
+    case "$verify" in
+      *"nvalid environment"*|*"Failed to resolve"*)
+        c_err "systemd does not parse the rendered unit: $verify"
+        return 1 ;;
+    esac
+  fi
+  systemctl --user daemon-reload
+  c_ok "deploy supervisor installed: the dashboard update button works"
+  if [ "${HESTIA_AUTO_UPDATE:-}" = 1 ]; then
+    systemctl --user enable --now hestia-deploy.timer
+    c_ok "auto-update ON (HESTIA_AUTO_UPDATE=1): deploys hestia main every 4h"
+  elif systemctl --user is-enabled --quiet hestia-deploy.timer 2>/dev/null; then
+    c_ok "auto-update already ON: left as it is"
+  else
+    c_dim "auto-update OFF: updates happen when you click update; switch it on in the dashboard"
+  fi
+}
+
 step_claude_hooks() {
   if [ -n "${HESTIA_SKIP_HOOK:-}" ]; then
     c_dim "claude-code hooks skipped (HESTIA_SKIP_HOOK set)"
@@ -915,6 +1052,7 @@ main() {
     *) c_err "unsupported OS"; exit 1 ;;
   esac
   step_workspace_marker
+  step_deploy_supervisor
   step_claude_hooks
   step_smoketest
   c_hdr "done"
diff --git a/deploy/from-main/README.md b/deploy/from-main/README.md
index a9dc55e6d..91a16b027 100644
--- a/deploy/from-main/README.md
+++ b/deploy/from-main/README.md
@@ -103,6 +103,14 @@ preflight and refuses identically, so there is nothing for the seat to retry.
 
 ## Install — Linux, user systemd (once per box)
 
+**On a checkout install, `deploy/fleet/install.sh` now does this for you** (`step_deploy_supervisor`):
+it clones the two deploy checkouts over https, installs `hestia-deploy` and both units with
+`HESTIA_WORKSPACE` rendered, and leaves the **timer off**. The dashboard's update button works
+straight away. Scheduled deploys stay off until the operator switches them on, either with the
+dashboard toggle (#1334) or with `HESTIA_AUTO_UPDATE=1` at install time. A release (`curl | sh`) install is
+skipped on purpose: it tracks releases, not main. The manual lines below remain the reference,
+and they are how a release install opts in to main-tracking.
+
     mkdir -p ~/.hestia/deploy
     git clone git@github.com:dp-web4/hestia.git ~/.hestia/deploy/hestia
     git clone git@github.com:dp-web4/web4.git   ~/.hestia/deploy/web4
diff --git a/tools/no_path_literals_test.py b/tools/no_path_literals_test.py
index 2b3ef340c..16409d28a 100755
--- a/tools/no_path_literals_test.py
+++ b/tools/no_path_literals_test.py
@@ -194,7 +194,7 @@
     "deploy/from-main/hestia-deploy.service":       {"unit-home-hestia": 2},
     "deploy/from-main/hestia-deploy.timer":         {},
     "deploy/from-main/hestia-deploy.sh":            {"shell-home-default": 3, "shell-home-hestia": 2},
-    "deploy/fleet/install.sh":                      {"shell-home-default": 1, "shell-home-hestia": 5, "unit-home-hestia": 4},
+    "deploy/fleet/install.sh":                      {"shell-home-hestia": 5, "unit-home-hestia": 4},
     "deploy/install-members.sh":                    {"expanduser-tilde": 1, "shell-home-default": 1, "shell-home-hestia": 1},
 }