Merge #370: ship systemd units that do not silently disable the daemon

fleetd #360. deploy/fleetd.service shipped four mount-namespacing directives
(ProtectSystem, ProtectHome, ProtectKernelTunables, ProtectControlGroups),
PrivateTmp=true, and an ExecStart that ran java directly. Each one starts green
and breaks the daemon in a way nothing logs: lsof goes blind so every caller is
resolved ANONYMOUS and refused; the member ZDOTDIR scrub becomes a no-op; every
credential is empty. deploy/herdr.service did not exist at all, though
fleetd.service's After=/Wants= already named it.

Both units are now the ones running on fleet01, comments included -- the
bisected lsof counts and the reasons live in the files, because the next person
to 'harden' this needs the reason, not the rule.

A unit file has no compile step, so SystemdUnitSafetyTest reads both units plus
deploy/herdr-inner.sh and fails on an active forbidden directive, on
PrivateTmp=true, on an ExecStart that skips the login shell, on a herdr-inner.sh
that does not exec a login shell, and on one that does not set a non-zero pty
size. Each message names the consequence. A vacuity guard pins that all three
files exist and that the DO-NOT-add comment block still mentions every forbidden
directive, so 'comment survives, directive does not' is actually exercised.

Verified on this merge, not taken from the worker's report:
  mvn clean install -> Tests run: 1420, Failures: 0, Errors: 0, BUILD SUCCESS

Round 1 shipped herdr-inner.sh untested; I mutated it (dropped both the login
shell and the stty sizing) and got 6 green. Round 2 added those two checks.

Mutation run on merge, on a half the worker never touched -- ProtectHome=read-only
added to herdr.service, the unit it only ever mutated fleetd.service for:
Tests run: 8, Failures: 1, BUILD FAILURE. The parameterisation really covers
both files.

deploy/fleetd.service

@@ -1,72 +1,72 @@
 # CB-504 — systemd unit for fleetd (Linux).
 #
-# The macOS launchd agent (deploy/dev.ltms.fleetd.plist) is the supervision target for the
-# current single-host deployment. This unit exists for the per-host gateways CB-308 introduces,
-# which will run on Linux.
+# fleetd #360: the previous version of this file started clean and broke the daemon in three ways
+# that nothing logs (see the DO NOT block and the ExecStart/PrivateTmp comments below for what and
+# why). The unit below, plus its companion deploy/herdr.service, is the version that has actually
+# run on fleet01 without those failures. Do not "improve" it back toward the old shape without
+# re-reading why each line is the way it is.
 #
 # Install (user service — fleetd drives the user's herdr, not a system daemon):
 #   mkdir -p ~/.config/systemd/user
-#   cp deploy/fleetd.service ~/.config/systemd/user/
-#   # edit ExecStart / WorkingDirectory / Environment below, then:
+#   cp deploy/fleetd.service deploy/herdr.service ~/.config/systemd/user/
+#   # edit WorkingDirectory / ExecStart below for your host's paths and java location
 #   systemctl --user daemon-reload
-#   systemctl --user enable --now fleetd
+#   systemctl --user enable --now herdr fleetd
 #   journalctl --user -u fleetd -f
+#
+# Secrets (AI_GATEWAY_TOKEN, WORKER_GITEA_TOKEN, LAVINMQ_URI, COORD_AMQP_URI, ...) are not set
+# here and need no systemd drop-in: ExecStart runs a login shell, so they come from wherever your
+# login shell already sources them (this host: ~/.fleet/secrets.sh via ~/.zprofile). If a token is
+# missing there, fleetd still starts — the daemon reports every secret a configured profile
+# references, by name, never by value:
+#   journalctl --user -u fleetd | grep 'startup secret'
+# A resolved one logs "startup secret NAME: set (profile 'x' tokenEnv)"; a missing one logs
+# "startup secret NAME: MISSING" at WARN and the daemon starts anyway — the first visible symptom
+# is a member that cannot open a pull request, hours later and in a different component.
 
 [Unit]
-Description=fleetd — claude-bridge message server
+Description=fleetd — fleet message server
 Documentation=https://git.ltms.dev/fleet/fleetd/wiki
-# Ordering only: herdr is a user process and its socket may appear after us. This is advisory —
-# fleetd retries the herdr socket rather than exiting, which is what actually makes a late
-# socket survivable. Do NOT add Requires=: a herdr restart must not take fleetd down with it.
+# Ordering only. fleetd retries the herdr socket rather than exiting, which is what actually makes
+# a late socket survivable. Do NOT add Requires=: a herdr restart must not take fleetd down too.
 After=herdr.service
 Wants=herdr.service
 
 [Service]
 Type=simple
-WorkingDirectory=%h/src/claude-bridge/fleetd
-ExecStart=/usr/lib/jvm/temurin-25-jdk/bin/java -jar target/fleetd.jar fleetd.yaml
+WorkingDirectory=%h/LTMS/fleetd/fleetd
 
-Environment=HERDR_SOCKET_PATH=%h/.config/herdr/herdr.sock
-# PATH matters more than it looks (CB-511): fleetd propagates its own PATH to every worker it
-# spawns, so this line decides whether the fleet can run a build at all. systemd does not source a
-# login shell, so without it the daemon — and every worker — gets a bare default with no JDK/Maven.
-Environment=PATH=/usr/lib/jvm/temurin-25-jdk/bin:/usr/share/maven/bin:/usr/local/bin:/usr/bin:/bin
-# Secrets are NOT set here — this file is committed. Put ALL three tokens in a private drop-in
-# that systemd reads with restrictive permissions. In `systemctl --user edit fleetd`, add:
-#   [Service]
-#   Environment=FLEETD_API_TOKEN=...
-#   Environment=WORKER_GITEA_TOKEN=...
-#   Environment=AI_GATEWAY_TOKEN=...
-# FLEETD_API_TOKEN protects fleetd's API. WORKER_GITEA_TOKEN lets members open pull requests; if
-# it is missing, fleetd still starts, but a member fails when it later tries to open a pull request.
-# AI_GATEWAY_TOKEN authenticates gateway profiles; if it is missing, fleetd still starts, but a
-# gateway profile later returns HTTP 401. Or, put the same three variables in a 0600 file and add:
-# EnvironmentFile=%h/.config/fleetd/env
-# After starting, check which of them actually resolved. The daemon reports every secret a
-# configured profile references, by name, never by value:
-#   journalctl --user -u fleetd | grep 'startup secret'
-# A resolved one logs "startup secret NAME: set (profile 'x' tokenEnv)". A missing one logs
-# "startup secret NAME: MISSING" at WARN — and the daemon starts anyway, which is the whole
-# problem: without this grep the first sign is a member that cannot open a pull request, hours
-# later and in a different component.
-# Note what the report can and cannot tell you. It lists only names some profile actually
-# references (tokenEnv, gitTokenEnv, and the broker uriEnv). A secret nothing references is never
-# reported, because nothing needs it.
+# A LOGIN shell, not java directly. Every secret this daemon needs (AI_GATEWAY_TOKEN,
+# WORKER_GITEA_TOKEN, LAVINMQ_URI, COORD_AMQP_URI) lives in ~/.fleet/secrets.sh, which only
+# ~/.zprofile sources. systemd runs no login shell. Started any other way the daemon boots fine
+# and looks healthy, and the failure appears hours later as a member that cannot open a pull
+# request. exec keeps it one process, so systemd tracks the right PID.
+# This also avoids a SECOND copy of the secrets in a systemd drop-in: one source of truth.
+ExecStart=/bin/zsh -lc "exec java -jar target/fleetd.jar fleetd.yaml"
+
+# PrivateTmp MUST stay false -- see herdr.service. fleetd creates the member ZDOTDIR scrub dir and
+# the opencode config dir under java.io.tmpdir, and the member pane (a herdr child, a different
+# unit) has to read them. A private /tmp turns the credential scrub into a silent no-op.
+PrivateTmp=false
 
 Restart=on-failure
 RestartSec=10s
-# A bad config (e.g. a non-loopback bind without token auth) makes fleetd fail fast by design.
-# Give up rather than restart-loop on a permanent error.
+# A bad config makes fleetd fail fast by design. Give up rather than restart-loop forever.
 StartLimitBurst=5
 StartLimitIntervalSec=120
 
-# The daemon reads the repo, writes worktrees, and talks to a Unix socket — it needs no more.
+# DO NOT add ProtectSystem=, ProtectHome=, ProtectKernelTunables= or ProtectControlGroups=.
+# Measured on fleet01 2026-09-05: each of those gives the unit its own mount namespace, and
+# fleetd resolves a caller role by running lsof to find the loopback peer PID
+# (mcp/LsofPeerPidLookup). Inside such a namespace lsof returns nothing, every caller falls back
+# to ANONYMOUS, and the primary is refused every orchestration call with
+# "unauthenticated: anonymous may not SPAWN".
+# The daemon still starts, healthz still returns ok and the secrets still resolve - the only
+# symptom is that the fleet cannot be driven at all. Verified by bisecting the directives:
+#   no sandbox 3 lsof lines | ProtectSystem=strict 0 | ProtectHome=read-only 0
+#   ProtectKernelTunables 0 | ProtectControlGroups 0 | RestrictSUIDSGID 3 | NoNewPrivileges 3
+# The two below add no mount namespace and are safe.
 NoNewPrivileges=true
-PrivateTmp=true
-ProtectSystem=strict
-ProtectHome=read-write
-ProtectKernelTunables=true
-ProtectControlGroups=true
 RestrictSUIDSGID=true
 
 StandardOutput=journal

deploy/herdr-inner.sh

@@ -0,0 +1,19 @@
+#!/bin/zsh
+# fleetd #360 — template for the script deploy/herdr.service's ExecStart wraps in a pty.
+#
+# `script -qfec <this> /dev/null` needs a real command to run, and that command has to be a LOGIN
+# shell script: herdr itself needs the same secrets fleetd.service's login shell picks up (this
+# host: ~/.fleet/secrets.sh via ~/.zprofile), because members it spawns inherit its environment.
+# systemd's own Environment= lines in herdr.service are not enough for that -- they set TERM and a
+# bare PATH so the pty starts at all, nothing more.
+#
+# Copy this file to the path deploy/herdr.service's ExecStart names
+# (%h/LTMS/fleetd/fleetd-run/herdr-inner.sh by default) and `chmod +x` it. Not committed under
+# that path itself because the session name below is host-specific.
+
+# A 0x0 pty makes every pane spawn fail with "ghostty error -2" (see herdr-multi-instance-facts /
+# fleet01-headless-herdr-standup) -- give it a real size before herdr ever touches it.
+stty rows 50 cols 200
+
+# -l: login shell, so herdr and everything it spawns gets the real secrets and PATH.
+exec zsh -lc 'exec herdr --session <name>'

deploy/herdr.service

@@ -0,0 +1,40 @@
+# fleetd #360 — systemd unit for herdr (Linux), the terminal multiplexer fleetd drives.
+#
+# This is fleetd.service's companion: fleetd.service's After=/Wants=herdr.service assumes this
+# unit exists. Before this ticket it did not, so on a fresh host fleetd started against a herdr
+# that systemd never supervised at all.
+#
+# Install: see deploy/fleetd.service's header comment (both units install the same way).
+#
+# ExecStart below runs deploy/herdr-inner.sh (copy the template of that name from this directory
+# to the path in ExecStart, or point ExecStart at wherever you keep it, and make it executable).
+# It is a separate file rather than an inline command because it must itself be a login shell (see
+# its own header for why) and systemd's ExecStart does not run one.
+
+[Unit]
+Description=herdr terminal multiplexer (fleet session)
+Documentation=https://git.ltms.dev/fleet/fleetd/wiki
+
+[Service]
+Type=simple
+# script(1) gives herdr a real pty. Without it the client reports a 0x0 window and every pane
+# spawn fails with "ghostty error -2" -- which surfaces as a fleetd spawn failure, not a herdr one.
+ExecStart=/usr/bin/script -qfec %h/LTMS/fleetd/fleetd-run/herdr-inner.sh /dev/null
+StandardInput=null
+Environment=TERM=xterm-256color
+Environment=PATH=%h/.local/bin:/usr/local/bin:/usr/bin:/bin
+
+# PrivateTmp MUST stay false. fleetd writes the member ZDOTDIR scrub dir and the opencode config
+# dir under its own java.io.tmpdir, and the member pane -- a child of THIS process -- has to read
+# them. A private /tmp here silently breaks the credential scrub instead of failing loudly.
+PrivateTmp=false
+
+Restart=on-failure
+RestartSec=5s
+
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=herdr
+
+[Install]
+WantedBy=default.target

fleetd/src/test/java/dev/ltms/fleet/deploy/SystemdUnitSafetyTest.java

@@ -0,0 +1,232 @@
+package dev.ltms.fleet.deploy;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * fleetd #360: {@code deploy/fleetd.service} started clean on fleet01 and broke the daemon in
+ * three ways that nothing logs at startup.
+ *
+ * <ul>
+ *   <li>{@code ProtectSystem=}, {@code ProtectHome=}, {@code ProtectKernelTunables=} and
+ *       {@code ProtectControlGroups=} each give the unit its own mount namespace. fleetd resolves
+ *       a caller's role by running {@code lsof} to find the loopback peer PID (see
+ *       {@code mcp/LsofPeerPidLookup}). Inside such a namespace {@code lsof} returns nothing,
+ *       every caller falls back to ANONYMOUS, and the primary is refused every orchestration call
+ *       with "unauthenticated: anonymous may not SPAWN" -- while healthz still reports ok.
+ *       Measured by bisection on fleet01 2026-09-05 (lsof line count): no sandbox 3,
+ *       {@code ProtectSystem=strict} 0, {@code ProtectHome=read-only} 0,
+ *       {@code ProtectKernelTunables} 0, {@code ProtectControlGroups} 0,
+ *       {@code RestrictSUIDSGID} 3, {@code NoNewPrivileges} 3 -- so only the first four are
+ *       forbidden.
+ *   <li>{@code PrivateTmp=true} gives the unit its own {@code /tmp}. fleetd writes the member
+ *       ZDOTDIR credential-scrub directory and the opencode config directory under
+ *       {@code java.io.tmpdir}, and the member pane -- a child of a *different* unit
+ *       (herdr.service) -- has to read them back. A private {@code /tmp} on either unit turns the
+ *       credential scrub into a silent no-op.
+ *   <li>Running {@code java} directly from {@code ExecStart} skips the login shell. Every secret
+ *       fleetd needs (AI_GATEWAY_TOKEN, WORKER_GITEA_TOKEN, LAVINMQ_URI, COORD_AMQP_URI) lives in
+ *       a file only the login shell sources; systemd runs no login shell on its own. Started that
+ *       way the daemon boots fine with empty credentials, and the failure appears hours later as a
+ *       member that cannot open a pull request.
+ * </ul>
+ *
+ * <p>Review round 2 on fleetd #360 found the same shape one file further down the chain:
+ * {@code herdr.service}'s {@code ExecStart} only names {@code deploy/herdr-inner.sh}, so that
+ * script is the ONLY place two more of these properties live, and nothing was reading it.
+ *
+ * <ul>
+ *   <li>If the script does not exec a login shell, herdr -- and every member pane it spawns as a
+ *       child -- starts with none of the secrets only a login shell sources, the same silent
+ *       empty-credentials failure as fleetd.service's {@code ExecStart}, one process further away.
+ *   <li>If the script does not set a real, non-zero pty size before starting herdr (with
+ *       {@code stty}), herdr reports a 0x0 window and every pane spawn fails with
+ *       "ghostty error -2" -- which surfaces as a fleetd spawn failure, not a herdr one.
+ * </ul>
+ *
+ * <p>None of these five failures makes the unit (or the script) fail to start, or makes
+ * {@code /healthz} report unhealthy, so nothing short of reading the files catches a regression.
+ * This test is that read.
+ *
+ * <p><b>It checks source text, not behaviour</b> -- it cannot start systemd or fork an mount
+ * namespace in a build sandbox. It parses the same two files an operator would install and fails
+ * if a forbidden directive is active, exactly the way {@code McpContractDocTest} guards
+ * {@code docs/MCP-Contract.md} against naming a tool that does not exist.
+ */
+class SystemdUnitSafetyTest {
+
+    /** Tests run with the module directory (fleetd/) as cwd; deploy/ is the repo-root sibling. */
+    private static final Path FLEETD_SERVICE = Path.of("../deploy/fleetd.service");
+    private static final Path HERDR_SERVICE = Path.of("../deploy/herdr.service");
+    private static final Path HERDR_INNER_SCRIPT = Path.of("../deploy/herdr-inner.sh");
+
+    private static final List<String> NAMESPACING_DIRECTIVES = List.of(
+            "ProtectSystem", "ProtectHome", "ProtectKernelTunables", "ProtectControlGroups");
+
+    /**
+     * A shell invoked with a login flag, e.g. {@code zsh -lc '...'} or {@code /bin/sh -l}. The
+     * property under test is the {@code -l}, not the specific shell or the rest of its flags, so
+     * this matches a token ending in "sh" followed by a flag cluster containing "l" -- tighter
+     * than a bare {@code contains("-lc")}, which a "-lc" anywhere in the line would also satisfy.
+     */
+    private static final Pattern LOGIN_SHELL_INVOCATION =
+            Pattern.compile("(?:^|\\s)\\S*sh\\s+-[A-Za-z]*l[A-Za-z]*\\b");
+
+    private static final Pattern POSITIVE_ROWS = Pattern.compile("\\brows\\s+([1-9]\\d*)\\b");
+    private static final Pattern POSITIVE_COLS = Pattern.compile("\\bcols\\s+([1-9]\\d*)\\b");
+
+    static Stream<Path> bothUnits() {
+        return Stream.of(FLEETD_SERVICE, HERDR_SERVICE);
+    }
+
+    private static boolean invokesALoginShell(List<String> activeLines) {
+        return activeLines.stream().anyMatch(l -> LOGIN_SHELL_INVOCATION.matcher(l).find());
+    }
+
+    /** An active {@code stty} line naming both a positive row count and a positive column count. */
+    private static boolean setsANonZeroPtySize(List<String> activeLines) {
+        return activeLines.stream()
+                .filter(l -> l.startsWith("stty"))
+                .anyMatch(l -> POSITIVE_ROWS.matcher(l).find() && POSITIVE_COLS.matcher(l).find());
+    }
+
+    /** Lines that are actually in force: comments and blank lines don't count. */
+    private static List<String> activeLines(Path unit) throws Exception {
+        List<String> active = new ArrayList<>();
+        for (String line : Files.readAllLines(unit)) {
+            String stripped = line.strip();
+            if (!stripped.isEmpty() && !stripped.startsWith("#")) {
+                active.add(stripped);
+            }
+        }
+        return active;
+    }
+
+    @ParameterizedTest
+    @MethodSource("bothUnits")
+    @DisplayName("[SOURCE TEXT] no active mount-namespacing directive -- it blinds lsof and turns every caller ANONYMOUS")
+    void doesNotActivateAMountNamespace(Path unit) throws Exception {
+        List<String> active = activeLines(unit);
+
+        for (String directive : NAMESPACING_DIRECTIVES) {
+            Pattern activeDirective = Pattern.compile("^" + Pattern.quote(directive) + "\\s*=");
+            List<String> hits = active.stream().filter(l -> activeDirective.matcher(l).find()).toList();
+            assertTrue(hits.isEmpty(),
+                    unit + " sets " + directive + " (" + hits + "). That directive gives the unit its "
+                            + "own mount namespace; inside it, fleetd's lsof-based caller lookup "
+                            + "(mcp/LsofPeerPidLookup) returns nothing, so every MCP caller falls back to "
+                            + "ANONYMOUS and the primary is refused every orchestration call with "
+                            + "\"unauthenticated: anonymous may not SPAWN\" -- while the daemon still "
+                            + "starts and /healthz still reports ok. Measured on fleet01 2026-09-05 "
+                            + "(fleetd #360). A commented-out mention in the file's own DO-NOT-add block "
+                            + "is fine; an active directive is not.");
+        }
+    }
+
+    @ParameterizedTest
+    @MethodSource("bothUnits")
+    @DisplayName("[SOURCE TEXT] PrivateTmp is not true -- it silently no-ops the credential scrub")
+    void privateTmpIsNotTrue(Path unit) throws Exception {
+        List<String> active = activeLines(unit);
+        Pattern privateTmpTrue = Pattern.compile("^PrivateTmp\\s*=\\s*true\\b");
+
+        boolean hasPrivateTmpTrue = active.stream().anyMatch(l -> privateTmpTrue.matcher(l).find());
+        assertFalse(hasPrivateTmpTrue,
+                unit + " sets PrivateTmp=true. fleetd writes the member ZDOTDIR credential-scrub "
+                        + "directory and the opencode config directory under java.io.tmpdir, and the "
+                        + "member pane -- a child of a DIFFERENT unit -- has to read them back. A "
+                        + "private /tmp on either unit turns the credential scrub into a silent no-op: "
+                        + "no error, no log line, the scrub just never happens (fleetd #360).");
+    }
+
+    @Test
+    @DisplayName("[SOURCE TEXT] fleetd.service's ExecStart goes through a login shell -- otherwise every secret is empty")
+    void execStartUsesALoginShell() throws Exception {
+        List<String> active = activeLines(FLEETD_SERVICE);
+        List<String> execStartLines = active.stream().filter(l -> l.startsWith("ExecStart=")).toList();
+
+        assertTrue(execStartLines.size() == 1,
+                FLEETD_SERVICE + " must have exactly one active ExecStart= line; found "
+                        + execStartLines.size() + ": " + execStartLines);
+
+        String execStart = execStartLines.get(0);
+        assertTrue(LOGIN_SHELL_INVOCATION.matcher(execStart).find(),
+                FLEETD_SERVICE + "'s ExecStart (" + execStart + ") does not run a login shell (a shell "
+                        + "invoked with a \"-l\" flag, e.g. \"zsh -lc\"). Every secret fleetd needs "
+                        + "(AI_GATEWAY_TOKEN, WORKER_GITEA_TOKEN, LAVINMQ_URI, COORD_AMQP_URI) lives in a "
+                        + "file only the login shell sources; systemd runs no login shell on its own. "
+                        + "Running java directly boots fine with every credential empty, and the failure "
+                        + "surfaces hours later as a member that cannot open a pull request (fleetd #360).");
+    }
+
+    @Test
+    @DisplayName("[SOURCE TEXT] herdr-inner.sh execs a login shell -- otherwise herdr and every member it spawns start with empty credentials")
+    void herdrInnerScriptUsesALoginShell() throws Exception {
+        List<String> active = activeLines(HERDR_INNER_SCRIPT);
+
+        assertTrue(invokesALoginShell(active),
+                HERDR_INNER_SCRIPT + " does not exec a login shell (a shell invoked with a \"-l\" flag, "
+                        + "e.g. \"zsh -lc\"). herdr.service's ExecStart only names this script, so this "
+                        + "is the ONLY place herdr's login-shell property lives. Without it, herdr -- and "
+                        + "every member pane it spawns as a child of herdr -- starts with none of the "
+                        + "secrets that only a login shell sources (this host: ~/.fleet/secrets.sh via "
+                        + "~/.zprofile), and the failure surfaces hours later as a member with no "
+                        + "credentials at all, not just fleetd (fleetd #360).");
+    }
+
+    @Test
+    @DisplayName("[SOURCE TEXT] herdr-inner.sh sets a non-zero pty size before starting herdr -- otherwise every pane spawn fails with \"ghostty error -2\"")
+    void herdrInnerScriptSetsANonZeroPtySize() throws Exception {
+        List<String> active = activeLines(HERDR_INNER_SCRIPT);
+
+        assertTrue(setsANonZeroPtySize(active),
+                HERDR_INNER_SCRIPT + " does not run \"stty rows N cols M\" with both N and M positive "
+                        + "before starting herdr. Without a real pty size, herdr reports a 0x0 window and "
+                        + "every pane spawn fails with \"ghostty error -2\" -- which surfaces as a fleetd "
+                        + "spawn failure, not a herdr one, and gives no hint that the actual cause is this "
+                        + "script (fleetd #360).");
+    }
+
+    /**
+     * The denominator guard, same shape as {@code McpContractDocTest}'s: a check that scans for a
+     * forbidden pattern passes trivially if it is handed nothing to scan. Pin that all three files
+     * exist, are non-trivial, and that the DO-NOT block's commented mentions are still there -- so
+     * the "comment survives, directive doesn't" distinction above is actually being exercised.
+     */
+    @Test
+    @DisplayName("[SOURCE TEXT] the namespacing check is not vacuous -- all three files exist and the DO-NOT block still mentions every forbidden directive in a comment")
+    void theCheckActuallyHasSomethingToCheck() throws Exception {
+        assertTrue(Files.size(FLEETD_SERVICE) > 200,
+                FLEETD_SERVICE + " is missing or unexpectedly small -- the checks above would pass "
+                        + "vacuously against an empty or absent file");
+        assertTrue(Files.size(HERDR_SERVICE) > 200,
+                HERDR_SERVICE + " is missing or unexpectedly small -- the checks above would pass "
+                        + "vacuously against an empty or absent file");
+        assertTrue(Files.size(HERDR_INNER_SCRIPT) > 50,
+                HERDR_INNER_SCRIPT + " is missing or unexpectedly small -- the login-shell and "
+                        + "pty-size checks above would either pass vacuously or fail with an opaque "
+                        + "\"file not found\" instead of naming the actual consequence (empty "
+                        + "credentials / \"ghostty error -2\") against an empty or absent file");
+
+        String fleetdService = Files.readString(FLEETD_SERVICE);
+        for (String directive : NAMESPACING_DIRECTIVES) {
+            assertTrue(fleetdService.contains(directive),
+                    FLEETD_SERVICE + " no longer mentions " + directive + " anywhere, not even in the "
+                            + "DO-NOT-add comment block that explains why it must stay out. That comment "
+                            + "is the whole point of fleetd #360 -- it is what stops the next edit from "
+                            + "re-adding the directive without knowing why.");
+        }
+    }
+}