fix(bin): forbid crewmates from administering shared worktrees

bin/fm-brief.sh

@@ -41,6 +41,10 @@
 # to launch a ship task whose explicit --mode disagrees, so an adjusted brief and the
 # recorded task metadata cannot drift apart.
 # Ship briefs begin with a worktree-isolation assertion before the branch step.
+# Both crewmate scaffolds carry one shared rule against administering the
+# infrastructure every lane shares - the no-mistakes daemon and the worktree pool
+# their own slot came from - so ship and scout cannot drift apart. A secondmate
+# charter omits it: that home allocates and returns slots for its own crewmates.
 # --mode is refused on scout and secondmate scaffolds: a scout's deliverable is a
 # report rather than a merge, and a charter is not a delivery contract.
 # There is no --yolo flag here. The worker never owns merge decisions, so yolo is
@@ -298,6 +302,28 @@ EOF
 HERDR_SECTION=${HERDR_SECTION%$'\n'}
 fi
 
+# One shared string keeps the ship and scout infrastructure rule identical.
+# Rule 2 governs file edits, so it does not prohibit pool administration.
+# The secondmate charter deliberately omits this rule because a secondmate
+# legitimately allocates and returns slots for crewmates in its own home.
+IFS= read -r -d '' SHARED_INFRA_RULE <<'EOF' || true
+7. Never administer infrastructure that every lane shares. Two things are shared:
+   - The `no-mistakes` daemon - one instance serving every lane/home, so stopping, restarting, or
+     updating it kills other lanes' in-flight pipeline runs. On ANY no-mistakes daemon error,
+     append `blocked: {the daemon error}` and stop; only firstmate manages the daemon.
+   - The worktree pool your own worktree came from, and the repository every lane's worktree
+     shares. Never create, remove, return, prune, move, or reassign a worktree or pool slot, and
+     never write into a sibling slot's directory. Rule 2 does not cover this: removing a worktree
+     is administration rather than an edit outside your directory, and it lands on lanes that are
+     running right now. The act is the rule and commands are only examples of it - `treehouse`
+     get/return/remove/prune, the equivalent operations on any other worktree provider or runtime
+     backend, and `git worktree add|remove|move|prune`. A slot that looks unused is not evidence
+     that it is free, and returning your own worktree is firstmate's job at cleanup, not yours.
+   If you genuinely need a second checkout, another slot, or the daemon touched, append
+   `blocked: {what you need}` and stop; firstmate arranges it.
+EOF
+SHARED_INFRA_RULE=${SHARED_INFRA_RULE%$'\n'}
+
 if [ "$KIND" = scout ]; then
 cat > "$BRIEF" <<EOF
 You are a crewmate: an autonomous worker agent managed by firstmate. Work on your own; do not wait for a human.
@@ -332,9 +358,7 @@ The report is the only thing that survives, so anything worth keeping must be in
    append \`needs-decision: {summary of options}\` and stop. Firstmate will reply with the decision.
    A decision or blocker you opened stays open until a \`resolved\` line carrying its exact key lands; a later \`done:\` or \`working:\` line never closes it, even when the answer is what started that work.
    Firstmate's reply normally writes that closing line at answer time; when a blocker or wait clears WITHOUT a firstmate reply, append \`resolved: {how it cleared}\` yourself (same \`[key=<slug>]\` if you opened it with one) as you resume.
-7. Never stop, restart, or update the shared \`no-mistakes\` daemon - it is one instance serving
-   every lane/home, so restarting it kills other lanes' in-flight pipeline runs. On ANY no-mistakes
-   daemon error, append \`blocked: {the daemon error}\` and stop; only firstmate manages the daemon.
+$SHARED_INFRA_RULE
 
 # Definition of done
 Write your findings to \`$DATA/$ID/report.md\`.
@@ -449,9 +473,7 @@ $RULE1
    append \`needs-decision: {summary of options}\` and stop. Firstmate will reply with the decision.
    A decision or blocker you opened stays open until a \`resolved\` line carrying its exact key lands; a later \`done:\` or \`working:\` line never closes it, even when the answer is what started that work.
    Firstmate's reply normally writes that closing line at answer time; when a blocker or wait clears WITHOUT a firstmate reply, append \`resolved: {how it cleared}\` yourself (same \`[key=<slug>]\` if you opened it with one) as you resume.
-7. Never stop, restart, or update the shared \`no-mistakes\` daemon - it is one instance serving
-   every lane/home, so restarting it kills other lanes' in-flight pipeline runs. On ANY no-mistakes
-   daemon error, append \`blocked: {the daemon error}\` and stop; only firstmate manages the daemon.
+$SHARED_INFRA_RULE
 
 # Project memory
 If \`AGENTS.md\` or \`CLAUDE.md\` already exists, or if this task produced durable project-intrinsic knowledge, run \`$FM_ROOT/bin/fm-ensure-agents-md.sh .\` in the worktree.

tests/fm-brief.test.sh

@@ -712,6 +712,71 @@ test_scout_and_secondmate_scaffold() {
   pass "fm-brief: scout and secondmate code paths still scaffold well-formed briefs"
 }
 
+# Rule 2 governs file edits rather than pool administration, so every crewmate
+# scaffold must prohibit the administrative act itself. The rule is emitted from
+# one shared string so the ship and scout copies cannot drift apart.
+test_crewmate_scaffolds_forbid_pool_administration() {
+  local home id brief mode ship_rule scout_rule
+  home="$TMP_ROOT/pool-admin-home"
+  mkdir -p "$home/data"
+
+  for mode in no-mistakes direct-PR local-only; do
+    id="brief-pool-$mode"
+    FM_HOME="$home" "$ROOT/bin/fm-brief.sh" "$id" alpha --mode "$mode" >/dev/null 2>&1 \
+      || fail "fm-brief.sh --mode $mode exited non-zero"
+    brief="$home/data/$id/brief.md"
+    assert_grep "worktree pool" "$brief" \
+      "$mode ship brief did not name the shared worktree pool"
+    assert_grep "create, remove, return, prune, move, or reassign" "$brief" \
+      "$mode ship brief did not state the prohibition around the act"
+    # shellcheck disable=SC2016 # Literal command text must remain unexpanded.
+    assert_grep 'git worktree add|remove|move|prune' "$brief" \
+      "$mode ship brief did not name the concrete git worktree commands"
+    assert_grep "treehouse" "$brief" \
+      "$mode ship brief did not name the treehouse mutation commands"
+    assert_grep "any other worktree provider" "$brief" \
+      "$mode ship brief pinned one provider instead of covering every provider"
+    assert_grep "sibling slot" "$brief" \
+      "$mode ship brief did not forbid writing into a sibling slot"
+    # shellcheck disable=SC2016 # Literal backticks and braces must remain unexpanded.
+    assert_grep 'blocked: {what you need}' "$brief" \
+      "$mode ship brief gave the prohibition no exit for a genuine second-checkout need"
+  done
+
+  FM_HOME="$home" "$ROOT/bin/fm-brief.sh" brief-pool-scout alpha --scout >/dev/null 2>&1 \
+    || fail "fm-brief.sh --scout exited non-zero"
+  brief="$home/data/brief-pool-scout/brief.md"
+  assert_grep "worktree pool" "$brief" "scout brief did not name the shared worktree pool"
+  # shellcheck disable=SC2016 # Literal backticks and braces must remain unexpanded.
+  assert_grep 'blocked: {what you need}' "$brief" "scout brief gave the prohibition no exit"
+
+  # One shared string, not two copies: the emitted rule must be byte-identical
+  # across the ship and scout scaffolds so a later edit cannot fix one and miss
+  # the other.
+  ship_rule=$(awk '/^7\. Never administer/,/^$/' "$home/data/brief-pool-no-mistakes/brief.md")
+  scout_rule=$(awk '/^7\. Never administer/,/^$/' "$brief")
+  [ -n "$ship_rule" ] || fail "ship brief emitted no shared-infrastructure rule to compare"
+  [ "$ship_rule" = "$scout_rule" ] \
+    || fail "ship and scout shared-infrastructure rules have drifted apart"
+
+  # The daemon half of the rule survived the fold.
+  assert_grep "no-mistakes" "$brief" "scout brief lost the shared no-mistakes daemon rule"
+  # shellcheck disable=SC2016 # Literal backticks and braces must remain unexpanded.
+  assert_grep 'blocked: {the daemon error}' "$brief" \
+    "scout brief lost the daemon-error reporting instruction"
+
+  # A secondmate runs its own home and legitimately allocates and returns slots
+  # for its own crewmates, so the crewmate prohibition must NOT reach its charter.
+  FM_SECONDMATE_CHARTER='Supervise the alpha domain.' \
+    FM_HOME="$home" "$ROOT/bin/fm-brief.sh" brief-pool-mate --secondmate alpha >/dev/null 2>&1 \
+    || fail "fm-brief.sh --secondmate exited non-zero"
+  assert_no_grep "create, remove, return, prune, move, or reassign" \
+    "$home/data/brief-pool-mate/brief.md" \
+    "secondmate charter must not inherit the crewmate pool-administration prohibition"
+
+  pass "fm-brief.sh: every crewmate scaffold forbids administering the shared worktree pool"
+}
+
 test_script_parses
 test_no_heredoc_in_command_substitution
 test_help_includes_entire_header
@@ -732,3 +797,4 @@ test_secondmate_directory_paths_are_absolute_and_output_is_stable
 test_pause_verb_override_renders_all_brief_scaffolds
 test_scout_and_secondmate_load_decision_hold_policy
 test_scout_and_secondmate_scaffold
+test_crewmate_scaffolds_forbid_pool_administration