#185: skip absent git paths, and resolve the git dir instead of assuming .git

Two defects in the stage-3 share pass, both of which would have failed EVERY
provisioning spawn once worktreeGroup was set, not only the two-user case.

.git/logs was handed to chgrp unguarded while packed-refs was guarded. It does
not exist with core.logAllRefUpdates=false, or before the first ref update, and
chgrp on a missing path exits non-zero -- surfacing as a WorktreeException that
blames a group which is in fact fine. Every path is now skipped when absent.

repoRoot + "/.git" was hardcoded. That is a FILE, not a directory, when the
checkout is itself a linked worktree -- the very thing this class creates for
every member. It now asks git: rev-parse --git-common-dir, resolved against
repoRoot because git answers relatively for an ordinary checkout.

Both new tests were watched failing with the fix removed before being kept.

fleetd/fleetd.example.yaml

@@ -634,6 +634,17 @@ guard:
 # to a sibling directory of the repo root.
 # worktreeRoot: /Users/me/src/.bridged-worktrees
 
+# Worktree group sharing (fleetd #185 stage 3). OPTIONAL, off by default. Names an OS group
+# that a provisioned worktree's repo is made group-writable for (git config
+# core.sharedRepository group, plus a one-time chgrp/chmod/setgid fix-up), so a member spawned
+# under a DIFFERENT OS user (see memberHerdrSocket) can write its own worktree, its
+# per-worktree git metadata, and its own commit objects — without it, every file GitWorktrees
+# creates is owned by fleetd's own uid and unwritable by another user.
+# CAUTION: this isolates credentials, not the repository — a member in the group can still
+# write the operator's git objects and refs in the shared repo. The operator running fleetd
+# must already be a member of the named group, or every provisioning spawn fails loudly.
+# worktreeGroup: fleet-workers
+
 # Session lifecycle limits (CB-303). All knobs are opt-in; omit or set to null to keep
 # the feature disabled. By default the daemon never reaps, caps, or drains sessions.
 #   idleTtlSeconds     → reap READY/DONE sessions idle longer than this (never BUSY/SPAWNING)

fleetd/src/main/java/dev/ltms/fleet/Fleetd.java

@@ -177,14 +177,14 @@ public final class Fleetd {
                     claudeProfiles, cfg.effectiveDefaultProfile(), System::getenv,
                     cfg.spawnReadyTimeoutMs(), cfg.spawnReadyPollMs(),
                     () -> config.get().fleet(),
-                    () -> config.get().memberCredentials()));
+                    () -> config.get().memberCredentials(), null, config::get));
         }
         if (!opencodeProfiles.isEmpty()) {
             adapters.add(new OpenCodeLauncher(router.memberAgents(), router.memberSpaces(),
                     opencodeProfiles, cfg.effectiveDefaultProfile(), System::getenv,
                     cfg.spawnReadyTimeoutMs(), cfg.spawnReadyPollMs(),
                     () -> config.get().fleet(),
-                    () -> config.get().memberCredentials()));
+                    () -> config.get().memberCredentials(), config::get));
         }
         AtomicReference<Function<String, Integer>> liveCountRef = new AtomicReference<>(_ -> 0);
         // CB-578 stage B: one quarantine tracker for the whole daemon, shared between the launcher
@@ -224,7 +224,7 @@ public final class Fleetd {
             contextCap = cfg.lifecycle().contextCap();
         }
         boolean clearAfterTurn = cfg.lifecycle() != null && cfg.lifecycle().clearAfterTurn();
-        SessionManager sessions = new SessionManager(workers, new GitWorktrees(cfg.worktreeRoot()),
+        SessionManager sessions = new SessionManager(workers, new GitWorktrees(cfg.worktreeRoot(), cfg.worktreeGroup()),
                 System::nanoTime, contextCap, clearAfterTurn);
         liveCountRef.set(profileName -> (int) sessions.roster().stream()
                 .filter(s -> profileName.equals(s.profile()))

fleetd/src/main/java/dev/ltms/fleet/config/FleetConfig.java

@@ -76,6 +76,14 @@ import java.util.Set;
  *                      stay on {@code broker}'s vhost). {@code null} → no lead mailbox is opened.
  *                      Config parsing + accessors only — nothing here wires it into a live
  *                      {@code LeadMailbox}; that is a separate ticket. See {@link Coordinator}.
+ * @param worktreeGroup optional OS group name (fleetd #185 stage 3) that makes a provisioned
+ *                      worktree's repo group-shared, so a member running as a different OS user
+ *                      (see {@code memberHerdrSocket}) can write its own worktree, its per-worktree
+ *                      git metadata, and its own commit objects. {@code null}/blank/empty ⇒ off,
+ *                      today's behaviour unchanged (every file stays owned by fleetd's own uid).
+ *                      <strong>This isolates credentials, not the repository</strong>: a member in
+ *                      the group can still write the operator's git objects and refs in the shared
+ *                      repo. See {@link dev.ltms.fleet.session.Worktrees#shareWithGroup}.
  */
 @JsonIgnoreProperties(ignoreUnknown = true)
 public record FleetConfig(
@@ -98,7 +106,20 @@ public record FleetConfig(
         ConfigReload configReload,
         Integer quarantineCooldownSeconds,
         MemberCredentials memberCredentials,
-        Coordinator coordinator) {
+        Coordinator coordinator,
+        String worktreeGroup) {
+
+    /** Back-compat form before the {@code worktreeGroup} key was added. */
+    public FleetConfig(Bind bind, String herdrSocket, String memberHerdrSocket, Map<String, Profile> profiles,
+                         Guard guard, String worktreeRoot, Lifecycle lifecycle, Integer spawnReadyTimeoutMs,
+                         Integer spawnReadyPollMs, Broker broker, Primary primary, Fleet fleet,
+                         LeadHeartbeat leadHeartbeat, Health health, String placement, Auth auth,
+                         ConfigReload configReload, Integer quarantineCooldownSeconds,
+                         MemberCredentials memberCredentials, Coordinator coordinator) {
+        this(bind, herdrSocket, memberHerdrSocket, profiles, guard, worktreeRoot, lifecycle, spawnReadyTimeoutMs,
+                spawnReadyPollMs, broker, primary, fleet, leadHeartbeat, health, placement, auth,
+                configReload, quarantineCooldownSeconds, memberCredentials, coordinator, null);
+    }
 
     /** Back-compat form before the {@code coordinator:} block was added. */
     public FleetConfig(Bind bind, String herdrSocket, Map<String, Profile> profiles, Guard guard,
@@ -109,7 +130,7 @@ public record FleetConfig(
                          MemberCredentials memberCredentials) {
         this(bind, herdrSocket, null, profiles, guard, worktreeRoot, lifecycle, spawnReadyTimeoutMs,
                 spawnReadyPollMs, broker, primary, fleet, leadHeartbeat, health, placement, auth,
-                configReload, quarantineCooldownSeconds, memberCredentials, null);
+                configReload, quarantineCooldownSeconds, memberCredentials, null, null);
     }
 
     /** Back-compat form before the CB-596 {@code memberCredentials:} block was added. */
@@ -1325,7 +1346,7 @@ public record FleetConfig(
             "bind", "herdrSocket", "memberHerdrSocket", "profiles", "guard", "worktreeRoot",
             "lifecycle", "spawnReadyTimeoutMs", "spawnReadyPollMs", "broker", "primary", "fleet",
             "leadHeartbeat", "health", "placement", "auth", "configReload", "quarantineCooldownSeconds",
-            "memberCredentials", "coordinator");
+            "memberCredentials", "coordinator", "worktreeGroup");
 
     /** Load and validate config from {@code path}. */
     public static FleetConfig load(Path path) {
@@ -1943,9 +1964,11 @@ public record FleetConfig(
                 : new MemberCredentials(null, List.of(), List.of());
         // coordinator is left as-is, like broker/primary above: null keeps no LeadMailbox opened,
         // and this ticket's Coordinator is config-only anyway (nothing yet reads it at startup).
+        // worktreeGroup is left as-is (fleetd #185 stage 3): null/blank is "off", and there is no
+        // sane non-null default — an OS group name is operator-specific.
         return new FleetConfig(b, herdrSocket, memberHerdrSocket, profiles, g, worktreeRoot, l, timeout, pollMs,
                 broker, primary, f, leadHeartbeat, health, placementOrDefault, a, configReload,
-                quarantineCooldown, mc, coordinator);
+                quarantineCooldown, mc, coordinator, worktreeGroup);
     }
 
     /**

fleetd/src/main/java/dev/ltms/fleet/herdr/PaneLocator.java

@@ -2,8 +2,11 @@ package dev.ltms.fleet.herdr;
 
 import com.fasterxml.jackson.databind.JsonNode;
 
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.OptionalLong;
+import java.util.Set;
 
 /**
  * Resolves which herdr pane a process belongs to — the herdr half of connection-based MCP
@@ -12,23 +15,46 @@ import java.util.Map;
  * is calling without the worker sending anything spoofable.
  *
  * <p>herdr owns the PID→pane truth: {@code pane.process_info} reports each pane's {@code shell_pid}
- * and foreground process PIDs. This scans agent panes; a spawn-time {@code pid→terminal} cache is
- * the obvious optimization once wired into {@code ClaudeCodeLauncher}.
+ * and foreground process PIDs. A pid that is neither of those directly — e.g. a grandchild a
+ * worker spawned, such as a {@code python3} or {@code curl} helper that opens its own MCP
+ * connection — is resolved by walking its ancestry (via {@link ParentResolver}) up to the root and
+ * matching any ancestor against a pane's {@code shell_pid} or foreground pids (CB-161). Without
+ * this walk such a pid matches no pane, and the caller falls through to loopback-trust and is
+ * resolved as the primary — a worker→primary privilege escalation.
+ *
+ * <p>This scans agent panes; a spawn-time {@code pid→terminal} cache is the obvious optimization
+ * once wired into {@code ClaudeCodeLauncher}.
  *
  * <p>CB-185 split the fleet across two herdr daemons — lead operations on one, members on the
  * other ({@code memberHerdrSocket}). A caller's pane can live on <em>either</em> daemon (a lead's
  * MCP connection resolves against the lead daemon; a member's against the member daemon), so this
  * must be able to search more than one client. {@link #PaneLocator(HerdrClient, HerdrClient)}
  * searches the lead client first, then the member client, and collapses to a single scan when the
- * two are the same object (the historical single-daemon deployment).
+ * two are the same object (the historical single-daemon deployment). The caller's ancestor set is
+ * computed once per {@link #terminalForPid} call and reused across every client searched — it
+ * does not depend on which daemon a pane happens to live on.
  */
 public final class PaneLocator {
 
+    /**
+     * Bound on how many ancestor generations {@link #ancestorsOf} walks. This runs on every MCP
+     * call, so a cycle or a pathologically deep process tree must not hang identity resolution;
+     * 32 generations is far more than any real worker→helper process tree needs.
+     */
+    private static final int MAX_ANCESTRY_DEPTH = 32;
+
     private final List<HerdrClient> herdrs;
+    private final ParentResolver parentResolver;
 
     /** Search only this client — the single-daemon deployment. */
     public PaneLocator(HerdrClient herdr) {
+        this(herdr, ParentResolver.PROCESS_HANDLE);
+    }
+
+    /** Search only this client, resolving ancestry through {@code parentResolver} — for tests. */
+    public PaneLocator(HerdrClient herdr, ParentResolver parentResolver) {
         this.herdrs = List.of(herdr);
+        this.parentResolver = parentResolver;
     }
 
     /**
@@ -37,7 +63,13 @@ public final class PaneLocator {
      * collapses to one client and one scan, exactly {@link #PaneLocator(HerdrClient)}'s behaviour.
      */
     public PaneLocator(HerdrClient lead, HerdrClient member) {
+        this(lead, member, ParentResolver.PROCESS_HANDLE);
+    }
+
+    /** Two-daemon deployment, resolving ancestry through {@code parentResolver} — for tests. */
+    public PaneLocator(HerdrClient lead, HerdrClient member, ParentResolver parentResolver) {
         this.herdrs = lead == member ? List.of(lead) : List.of(lead, member);
+        this.parentResolver = parentResolver;
     }
 
     /**
@@ -49,8 +81,9 @@ public final class PaneLocator {
         if (pid <= 0) {
             return null;
         }
+        Set<Long> ancestry = ancestorsOf(pid);
         for (HerdrClient herdr : herdrs) {
-            String terminal = terminalForPid(herdr, pid);
+            String terminal = terminalForPid(herdr, ancestry);
             if (terminal != null) {
                 return terminal;
             }
@@ -58,28 +91,54 @@ public final class PaneLocator {
         return null;
     }
 
-    private static String terminalForPid(HerdrClient herdr, long pid) {
+    /**
+     * {@code pid} itself plus its ancestor chain, walked through {@link #parentResolver} up to
+     * {@link #MAX_ANCESTRY_DEPTH} generations or pid 1, whichever comes first. A vanished ancestor
+     * ({@link ParentResolver#parentOf} returning empty) ends the walk without error — it just means
+     * the chain is shorter than the bound. A cycle in a fake resolver is caught by the "already
+     * seen" check and also ends the walk, so this can never loop.
+     */
+    private Set<Long> ancestorsOf(long pid) {
+        Set<Long> ancestry = new LinkedHashSet<>();
+        long current = pid;
+        for (int depth = 0; depth < MAX_ANCESTRY_DEPTH; depth++) {
+            if (current <= 0 || !ancestry.add(current)) {
+                break; // vanished/invalid pid, or a cycle back to a pid already recorded
+            }
+            if (current == 1) {
+                break; // reached the root of the process tree
+            }
+            OptionalLong parent = parentResolver.parentOf(current);
+            if (parent.isEmpty()) {
+                break; // vanished ancestor — not an error, just the end of the chain
+            }
+            current = parent.getAsLong();
+        }
+        return ancestry;
+    }
+
+    private static String terminalForPid(HerdrClient herdr, Set<Long> ancestry) {
         for (JsonNode pane : herdr.call("pane.list", Map.of()).path("panes")) {
             String paneId = pane.path("pane_id").asText(null);
-            if (paneId != null && paneOwnsPid(herdr, paneId, pid)) {
+            if (paneId != null && paneOwnsAnyOf(herdr, paneId, ancestry)) {
                 return pane.path("terminal_id").asText(null);
             }
         }
         return null;
     }
 
-    private static boolean paneOwnsPid(HerdrClient herdr, String paneId, long pid) {
+    private static boolean paneOwnsAnyOf(HerdrClient herdr, String paneId, Set<Long> ancestry) {
         JsonNode info;
         try {
             info = herdr.call("pane.process_info", Map.of("pane_id", paneId)).path("process_info");
         } catch (HerdrException e) {
             return false; // pane vanished mid-scan — just skip it
         }
-        if (info.path("shell_pid").asLong(-1) == pid) {
+        if (ancestry.contains(info.path("shell_pid").asLong(-1))) {
             return true;
         }
         for (JsonNode p : info.path("foreground_processes")) {
-            if (p.path("pid").asLong(-1) == pid) {
+            if (ancestry.contains(p.path("pid").asLong(-1))) {
                 return true;
             }
         }

fleetd/src/main/java/dev/ltms/fleet/herdr/ParentResolver.java

@@ -0,0 +1,21 @@
+package dev.ltms.fleet.herdr;
+
+import java.util.OptionalLong;
+
+/**
+ * Resolves a pid's parent pid — the seam {@link PaneLocator} walks a process's ancestry through,
+ * so its tests can drive the walk from a fake pid→parent map instead of spawning real processes.
+ *
+ * <p>{@link #PROCESS_HANDLE} is the production implementation, backed by {@link ProcessHandle}.
+ */
+public interface ParentResolver {
+
+    /** The parent pid of {@code pid}, or empty if {@code pid} is gone or has no known parent. */
+    OptionalLong parentOf(long pid);
+
+    /** Production resolver: asks the JVM's {@link ProcessHandle} view of the OS process tree. */
+    ParentResolver PROCESS_HANDLE = pid -> ProcessHandle.of(pid)
+            .flatMap(ProcessHandle::parent)
+            .map(parent -> OptionalLong.of(parent.pid()))
+            .orElse(OptionalLong.empty());
+}

fleetd/src/main/java/dev/ltms/fleet/member/ClaudeCodeLauncher.java

@@ -94,13 +94,26 @@ public final class ClaudeCodeLauncher extends HerdrPeerLauncher {
     public ClaudeCodeLauncher(AgentControl agents, WorkspaceControl spaces, SubscriptionGuard guard,
                               Map<String, FleetConfig.Profile> profiles, String defaultProfile,
                               Function<String, String> env,
-                              long spawnReadyTimeoutMs, long spawnReadyPollMs,
-                              Supplier<FleetConfig.Fleet> fleet,
-                              Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+                               long spawnReadyTimeoutMs, long spawnReadyPollMs,
+                               Supplier<FleetConfig.Fleet> fleet,
+                               Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+        this(agents, spaces, guard, profiles, defaultProfile, env, spawnReadyTimeoutMs, spawnReadyPollMs,
+                fleet, memberCredentials, null, null);
+    }
+
+    /** Production constructor, plus the live config for URI environment exclusions. */
+    public ClaudeCodeLauncher(AgentControl agents, WorkspaceControl spaces, SubscriptionGuard guard,
+                               Map<String, FleetConfig.Profile> profiles, String defaultProfile,
+                               Function<String, String> env,
+                               long spawnReadyTimeoutMs, long spawnReadyPollMs,
+                               Supplier<FleetConfig.Fleet> fleet,
+                               Supplier<FleetConfig.MemberCredentials> memberCredentials,
+                               Supplier<Set<String>> hostEnvNames,
+                               Supplier<FleetConfig> config) {
         this(agents, spaces, guard, profiles, defaultProfile, env,
                 spawnReadyTimeoutMs,
                 System::currentTimeMillis, () -> sleepUninterruptibly(spawnReadyPollMs),
-                fleet, memberCredentials);
+                fleet, memberCredentials, hostEnvNames, config);
     }
 
     /**
@@ -153,10 +166,22 @@ public final class ClaudeCodeLauncher extends HerdrPeerLauncher {
                               Function<String, String> env,
                               long spawnReadyTimeoutMs,
                               LongSupplier nowMillis, Runnable sleeper,
-                              Supplier<FleetConfig.Fleet> fleet,
-                              Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+                               Supplier<FleetConfig.Fleet> fleet,
+                               Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+        this(agents, spaces, guard, profiles, defaultProfile, env, spawnReadyTimeoutMs, nowMillis, sleeper,
+                fleet, memberCredentials, null, null);
+    }
+
+    /** Full testability constructor, plus the live config for URI environment exclusions. */
+    public ClaudeCodeLauncher(AgentControl agents, WorkspaceControl spaces, SubscriptionGuard guard,
+                               Map<String, FleetConfig.Profile> profiles, String defaultProfile,
+                               Function<String, String> env, long spawnReadyTimeoutMs,
+                               LongSupplier nowMillis, Runnable sleeper, Supplier<FleetConfig.Fleet> fleet,
+                               Supplier<FleetConfig.MemberCredentials> memberCredentials,
+                               Supplier<Set<String>> hostEnvNames,
+                               Supplier<FleetConfig> config) {
         super(NAME_PREFIX, agents, spaces, profiles, defaultProfile, env,
-                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials);
+                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials, hostEnvNames, config);
         this.guard = guard;
     }
 
@@ -174,7 +199,7 @@ public final class ClaudeCodeLauncher extends HerdrPeerLauncher {
                               Supplier<FleetConfig.MemberCredentials> memberCredentials,
                               Supplier<Set<String>> hostEnvNames) {
         super(NAME_PREFIX, agents, spaces, profiles, defaultProfile, env,
-                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials, hostEnvNames);
+                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials, hostEnvNames, null);
         this.guard = guard;
     }
 

fleetd/src/main/java/dev/ltms/fleet/member/HerdrPeerLauncher.java

@@ -170,6 +170,8 @@ public abstract class HerdrPeerLauncher implements PeerLauncher {
 
     /** Guards {@link #warnNonZsh} to one WARN per launcher instance, not one per spawn. */
     private final AtomicBoolean nonZshShellWarned = new AtomicBoolean();
+    /** Live config provides URI environment names that must never enter member panes. */
+    private final Supplier<FleetConfig> config;
 
     /**
      * @param namePrefix          label prefix for this peer kind (drives naming and reap)
@@ -238,8 +240,19 @@ public abstract class HerdrPeerLauncher implements PeerLauncher {
                                 long spawnReadyTimeoutMs,
                                 LongSupplier nowMillis, Runnable sleeper,
                                 Supplier<FleetConfig.Fleet> fleet,
+                                 Supplier<FleetConfig.MemberCredentials> memberCredentials,
+                                 Supplier<Set<String>> hostEnvNames) {
+        this(namePrefix, agents, spaces, profiles, defaultProfile, env, spawnReadyTimeoutMs, nowMillis,
+                sleeper, fleet, memberCredentials, hostEnvNames, null);
+    }
+
+    /** As above, plus the live full config for secret-bearing URI environment names. */
+    protected HerdrPeerLauncher(String namePrefix, AgentControl agents, WorkspaceControl spaces,
+                                Map<String, FleetConfig.Profile> profiles, String defaultProfile,
+                                Function<String, String> env, long spawnReadyTimeoutMs,
+                                LongSupplier nowMillis, Runnable sleeper, Supplier<FleetConfig.Fleet> fleet,
                                 Supplier<FleetConfig.MemberCredentials> memberCredentials,
-                                Supplier<Set<String>> hostEnvNames) {
+                                Supplier<Set<String>> hostEnvNames, Supplier<FleetConfig> config) {
         this.fleet = fleet;
         this.namePrefix = namePrefix;
         this.agents = agents;
@@ -252,6 +265,7 @@ public abstract class HerdrPeerLauncher implements PeerLauncher {
         this.sleeper = sleeper;
         this.memberCredentials = memberCredentials;
         this.hostEnvNames = hostEnvNames != null ? hostEnvNames : () -> System.getenv().keySet();
+        this.config = config;
     }
 
     // --- adapter seams -------------------------------------------------------------------------
@@ -1028,9 +1042,11 @@ public abstract class HerdrPeerLauncher implements PeerLauncher {
     }
 
     /** Put {@link #BLOCKED_CREDENTIAL_SENTINEL} over every blocked name in the pane-creation env map. */
-    private static void overlayBlockedCredentials(Map<String, String> workerEnv,
-                                                  FleetConfig.MemberCredentials creds) {
-        for (String name : creds.blockedSet()) {
+    private void overlayBlockedCredentials(Map<String, String> workerEnv,
+                                          FleetConfig.MemberCredentials creds) {
+        Set<String> blocked = new java.util.TreeSet<>(creds.blockedSet());
+        blocked.addAll(brokerUriEnvNames());
+        for (String name : blocked) {
             workerEnv.put(name, BLOCKED_CREDENTIAL_SENTINEL);
         }
     }
@@ -1097,15 +1113,21 @@ public abstract class HerdrPeerLauncher implements PeerLauncher {
      * ssh-agent handle when explicitly allowed, and the exact keys of THIS launch's own env map.
      */
     private Set<String> derivedAllowedNames(FleetConfig.MemberCredentials creds, Launch launch) {
+        Set<String> brokerUriEnvNames = brokerUriEnvNames();
         Set<String> allowed = new java.util.TreeSet<>(
-                MemberEnvAllowList.derive(profiles.values(), creds.allowSet()));
+                MemberEnvAllowList.derive(profiles.values(), creds.allowSet(), brokerUriEnvNames));
         if (creds.sshAuthSockAllowed()) {
             allowed.add(SSH_AUTH_SOCK);
         } // blocked by default: absent from the set ⇒ blanked by the scrub like any other name
         allowed.addAll(launch.env().keySet());
+        allowed.removeAll(brokerUriEnvNames);
         return allowed;
     }
 
+    private Set<String> brokerUriEnvNames() {
+        return MemberEnvAllowList.brokerUriEnvNames(config == null ? null : config.get());
+    }
+
     /**
      * CB-633 follow-up: one INFO line per allow-list spawn WHOSE SCRUB ACTUALLY RUNS, so an operator
      * can read a single log line and know the scrub ran and how much of the visible environment it

fleetd/src/main/java/dev/ltms/fleet/member/MemberEnvAllowList.java

@@ -40,8 +40,9 @@ import java.util.TreeSet;
  * operator's own explicit list. Before this, {@code policy: allow-list} silently ignored every name
  * an operator wrote under {@code allow:} unless a profile happened to carry it too, which meant
  * turning the policy on could blank credentials working members already depended on. {@code
- * SSH_AUTH_SOCK} is the one exception: even when the operator lists it under {@code allow:}, it is
- * excluded here and added back ONLY by the caller when {@code sshAuthSock: allow} is explicitly set
+ * SSH_AUTH_SOCK} and configured broker URI environment names are exceptions: even when the operator
+ * lists them under {@code allow:}, they are excluded here. {@code SSH_AUTH_SOCK} is added back ONLY
+ * by the caller when {@code sshAuthSock: allow} is explicitly set
  * (see {@link #SSH_AUTH_SOCK}'s javadoc) — it is a live handle to the operator's own ssh-agent, not
  * a value, so treating it like any other allow-listed name would hand a member every key the
  * operator's agent holds the moment they typed the name under {@code allow:} for an unrelated
@@ -106,6 +107,16 @@ public final class MemberEnvAllowList {
      * run-to-run.
      */
     public static Set<String> derive(Collection<FleetConfig.Profile> profiles, Set<String> configuredAllow) {
+        return derive(profiles, configuredAllow, Set.of());
+    }
+
+    /**
+     * As {@link #derive(Collection, Set)}, while excluding names that fleetd knows carry credentials.
+     * A configured broker URI contains its AMQP password inline, so it must never reach a member,
+     * even when an operator put its variable name in {@code memberCredentials.allow:}.
+     */
+    public static Set<String> derive(Collection<FleetConfig.Profile> profiles, Set<String> configuredAllow,
+                                     Set<String> excludedNames) {
         Set<String> derived = new TreeSet<>(INFRASTRUCTURE_PASSTHROUGH);
         if (profiles != null) {
             for (FleetConfig.Profile p : profiles) {
@@ -124,9 +135,37 @@ public final class MemberEnvAllowList {
                 }
             }
         }
+        if (excludedNames != null) {
+            derived.removeAll(excludedNames);
+        }
         return Set.copyOf(derived);
     }
 
+    /**
+     * The host environment names whose values are AMQP URIs with inline passwords. Both broker
+     * connections belong to fleetd, never to a member pane. Blank and absent configuration changes
+     * nothing.
+     *
+     * <p><b>How strong this exclusion is depends on the policy, and the difference matters.</b>
+     * Under {@code policy: allow-list} it is enforced by the generated ZDOTDIR scrub, which runs
+     * AFTER the pane's shell has sourced the operator's chain — so a login shell that re-exports the
+     * name is still blanked. Under the deny-list policy there is no scrub: the name is only removed
+     * from the pre-shell env map, and a login shell that sources the operator's secret store
+     * re-exports it. That is the long-standing weakness of deny-list (a sourced file can undo it),
+     * not something this exclusion introduces, but it means deny-list deployments do NOT get this
+     * guarantee. The same caveat applies to the non-zsh path, which has no scrub at all — see
+     * {@code HerdrPeerLauncher#applyEnvironmentAllowListPolicy}.
+     */
+    public static Set<String> brokerUriEnvNames(FleetConfig config) {
+        if (config == null) {
+            return Set.of();
+        }
+        Set<String> names = new TreeSet<>();
+        addUriEnvIfPresent(names, config.broker());
+        addUriEnvIfPresent(names, config.coordinator());
+        return Set.copyOf(names);
+    }
+
     /**
      * Whether {@code name} survives the scrub when {@code allowedNames} is the derived set: an exact
      * match, or an infrastructure-prefixed name ({@code LC_*}). Prefix rules live ONLY here and in
@@ -146,4 +185,16 @@ public final class MemberEnvAllowList {
             into.add(name);
         }
     }
+
+    private static void addUriEnvIfPresent(Set<String> into, FleetConfig.Broker broker) {
+        if (broker != null && broker.hasUriEnv()) {
+            into.add(broker.uriEnv());
+        }
+    }
+
+    private static void addUriEnvIfPresent(Set<String> into, FleetConfig.Coordinator coordinator) {
+        if (coordinator != null && coordinator.hasUriEnv()) {
+            into.add(coordinator.uriEnv());
+        }
+    }
 }

fleetd/src/main/java/dev/ltms/fleet/member/OpenCodeLauncher.java

@@ -116,12 +116,23 @@ public final class OpenCodeLauncher extends HerdrPeerLauncher {
     public OpenCodeLauncher(AgentControl agents, WorkspaceControl spaces,
                             Map<String, FleetConfig.Profile> profiles, String defaultProfile,
                             Function<String, String> env,
-                            long spawnReadyTimeoutMs, long spawnReadyPollMs,
-                            Supplier<FleetConfig.Fleet> fleet,
-                            Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+                             long spawnReadyTimeoutMs, long spawnReadyPollMs,
+                             Supplier<FleetConfig.Fleet> fleet,
+                             Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+        this(agents, spaces, profiles, defaultProfile, env, spawnReadyTimeoutMs, spawnReadyPollMs,
+                fleet, memberCredentials, null);
+    }
+
+    /** Production constructor, plus the live config for URI environment exclusions. */
+    public OpenCodeLauncher(AgentControl agents, WorkspaceControl spaces,
+                             Map<String, FleetConfig.Profile> profiles, String defaultProfile,
+                             Function<String, String> env, long spawnReadyTimeoutMs, long spawnReadyPollMs,
+                             Supplier<FleetConfig.Fleet> fleet,
+                             Supplier<FleetConfig.MemberCredentials> memberCredentials,
+                             Supplier<FleetConfig> config) {
         this(agents, spaces, profiles, defaultProfile, env, spawnReadyTimeoutMs,
                 System::currentTimeMillis, () -> sleepUninterruptibly(spawnReadyPollMs),
-                defaultConfigRoot(), defaultDiscoveryRoot(), fleet, memberCredentials);
+                defaultConfigRoot(), defaultDiscoveryRoot(), fleet, memberCredentials, config);
     }
 
     /**
@@ -182,8 +193,20 @@ public final class OpenCodeLauncher extends HerdrPeerLauncher {
                             Path configRoot, Path discoveryRoot,
                             Supplier<FleetConfig.Fleet> fleet,
                             Supplier<FleetConfig.MemberCredentials> memberCredentials) {
+        this(agents, spaces, profiles, defaultProfile, env, spawnReadyTimeoutMs, nowMillis, sleeper,
+                configRoot, discoveryRoot, fleet, memberCredentials, null);
+    }
+
+    /** Full testability constructor, plus the live config for URI environment exclusions. */
+    public OpenCodeLauncher(AgentControl agents, WorkspaceControl spaces,
+                             Map<String, FleetConfig.Profile> profiles, String defaultProfile,
+                             Function<String, String> env, long spawnReadyTimeoutMs,
+                             LongSupplier nowMillis, Runnable sleeper, Path configRoot, Path discoveryRoot,
+                             Supplier<FleetConfig.Fleet> fleet,
+                             Supplier<FleetConfig.MemberCredentials> memberCredentials,
+                             Supplier<FleetConfig> config) {
         super(NAME_PREFIX, agents, spaces, profiles, defaultProfile, env,
-                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials);
+                spawnReadyTimeoutMs, nowMillis, sleeper, fleet, memberCredentials, null, config);
         this.configRoot = configRoot;
         this.discovery = new OpenCodeSessionDiscovery(discoveryRoot);
     }

fleetd/src/main/java/dev/ltms/fleet/msg/MessageService.java

@@ -366,21 +366,40 @@ public final class MessageService {
     }
 
     /**
-     * Route a worker's explicit {@code fleet_reply}: resolve an open send, or queue it in the
-     * inbox if no send is currently open. Unlike the bare {@link Rendezvous#resolve}, a no-waiter
-     * result is <em>not</em> a failure — the reply is held for later drain.
+     * Route a worker's explicit {@code fleet_reply}: resolve an open send, complete an async ticket
+     * still parked waiting on this exact turn's answer, or — only once neither applies — queue it in
+     * the inbox. Unlike the bare {@link Rendezvous#resolve}, a no-waiter result is <em>not</em> a
+     * failure — the reply is held for later drain.
      *
      * <p><strong>Do NOT use this for mid-turn questions.</strong> {@code fleet_ask} /
      * {@link Rendezvous#resolveQuestion} must keep today's {@code NO_WAITER} behaviour — questions
      * are interactive and must never be queued.
      *
-     * @return always {@code true} — the reply either resolved a live send or was queued
+     * @return always {@code true} — the reply resolved a live send, completed a parked ticket, or
+     *         was queued
      */
     public boolean reply(String session, String content) {
         if (rendezvous.resolve(session, content)) {
             count(FleetMetrics.REPLIES, "path", "rendezvous");
             return true;                       // a live send took it — unchanged fast path
         }
+        // #137: no live rendezvous waiter, but this may be the worker's real fleet_reply resuming a
+        // turn that {@link #answer} already gave up waiting on. answer()'s own bounded wait (the
+        // primary's fleet_send{turnId} call, capped well under a minute) can time out and close its
+        // waiter long before the worker — now actually resuming real work — finishes and replies. That
+        // reply used to have nowhere to land but the session inbox, leaving the async ticket's future
+        // unresolved forever: fleet_poll{ticket} stayed PENDING until fleet_stop's abandon() forced it
+        // FAILED with a misleading "session released before it replied" reason, even though the reply
+        // had, in fact, arrived. Completing the matching ticket directly here means fleet_poll{ticket}
+        // sees the real reply instead.
+        Task orphan = askAnsweredAsyncTask(session);
+        if (orphan != null && orphan.future.complete(new Reply(Outcome.REPLIED, content))) {
+            if (orphan.turnId != null) {
+                asyncTasksByTurn.remove(orphan.turnId, orphan);
+            }
+            count(FleetMetrics.REPLIES, "path", "async-recovered");
+            return true;                       // the ticket itself took it — no inbox stranding at all
+        }
         inbox.publish(session, UUID.randomUUID().toString(), content);
         // CB-640: record the stranding itself (not just the reply text) so fleet health can see a
         // worker whose replies keep missing their waiter, not only the queue depth this leaves behind.
@@ -394,6 +413,24 @@ public final class MessageService {
         return true;                           // held, not lost
     }
 
+    /**
+     * The still-open async task on {@code target} whose {@code fleet_ask} was already answered — its
+     * {@link Task#turnId} is stamped but its {@link Task#question} was cleared by {@link #answer} —
+     * yet whose future is not resolved yet (#137). {@code null} if no such task exists, including the
+     * common case where {@code target}'s worker never used {@code fleet_ask} at all (a task that was
+     * never asked has {@code turnId == null}, so it can never match here and only ever completes
+     * through the ordinary rendezvous fast path in {@link #reply}).
+     */
+    private Task askAnsweredAsyncTask(String target) {
+        for (Task task : tasks.values()) {
+            if (target.equals(task.target) && task.question == null && task.turnId != null
+                    && !task.future.isDone()) {
+                return task;
+            }
+        }
+        return null;
+    }
+
     /** Record a counter sample when a registry is wired; a no-op in unit tests. */
     private void count(String name, String... labels) {
         if (metrics != null) {
@@ -435,19 +472,43 @@ public final class MessageService {
      * <p>Resolving the waiter as a failure — rather than letting it time out — also means the
      * outcome is counted, so a torn-down delegation stops being invisible to {@code /metrics}.
      *
-     * @return true if a live waiter was failed
+     * <p><strong>#137 defence in depth.</strong> {@link #reply} already hands a worker's real
+     * {@code fleet_reply} straight to the async ticket it belongs to whenever one is still parked
+     * waiting for it (see {@link #askAnsweredAsyncTask}), so by the time a session is released its
+     * tasks are normally already resolved — this loop's {@code complete} calls are then harmless
+     * no-ops (a {@link CompletableFuture} can only resolve once). But should some other path someday
+     * strand a reply in the inbox without completing its ticket, checking
+     * {@link #hasStrandedReply(String)} here — before ever writing a failure — means a torn-down
+     * session whose worker in fact replied is still reported {@code REPLIED} with that reply's own
+     * text, never the misleading "the worker session was released before it replied" (which also
+     * means the snapshot/worktree recovery hint that follows it never prints once a reply exists).
+     *
+     * @return true if a live waiter or an async task was failed (never true for one recovered as a
+     *         reply — see the note above)
      */
     public boolean abandon(String target, String reason) {
+        boolean hadStrandedReply = hasStrandedReply(target);
         // CB-640: the session is gone — nothing will ever accept or deliver into it now.
         strandedReplies.remove(target);
         queuedDeliveries.remove(target);
         CompletableFuture<Rendezvous.Resolution> waiter = rendezvous.currentWaiter(target);
         boolean failed = waiter != null && !waiter.isDone() && rendezvous.resolveFailure(waiter, reason);
         boolean asyncFailed = false;
+        Reply recovered = null; // lazily drained at most once, only if a task actually needs it
         for (Task task : tasks.values()) {
-            if (target.equals(task.target) && task.question == null
-                    && task.future.complete(new Reply(Outcome.WORKER_FAILED, reason))) {
-                asyncFailed = true;
+            if (!target.equals(task.target) || task.question != null || task.future.isDone()) {
+                continue;
+            }
+            if (hadStrandedReply && recovered == null) {
+                recovered = recoverStrandedReply(target);
+            }
+            Reply outcome = recovered != null ? recovered : new Reply(Outcome.WORKER_FAILED, reason);
+            if (task.future.complete(outcome)) {
+                if (outcome.outcome() == Outcome.WORKER_FAILED) {
+                    asyncFailed = true;
+                } else if (task.turnId != null) {
+                    asyncTasksByTurn.remove(task.turnId, task);
+                }
             }
         }
         if (failed) {
@@ -456,6 +517,21 @@ public final class MessageService {
         return failed || asyncFailed;
     }
 
+    /**
+     * Drain {@code target}'s inbox and hand its content back as a {@link Outcome#REPLIED} result
+     * (#137 defence in depth for {@link #abandon}) — {@code null} if it turned out empty (the
+     * stranding fact raced away, e.g. a lead's own {@code fleet_poll} on the raw session already
+     * drained it first). When more than one message is queued, only the newest is the worker's actual
+     * final answer ({@link #drainReplies} returns them oldest-first).
+     */
+    private Reply recoverStrandedReply(String target) {
+        var messages = drainReplies(target);
+        if (messages.isEmpty()) {
+            return null;
+        }
+        return new Reply(Outcome.REPLIED, messages.get(messages.size() - 1).content());
+    }
+
     /**
      * Acknowledge a specific reply by {@code msgId} for {@code target}. Removes it from the inbox
      * so that a subsequent drain or peek no longer returns it.

fleetd/src/main/java/dev/ltms/fleet/session/GitWorktrees.java

@@ -23,6 +23,7 @@ import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.Consumer;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 
 /**
@@ -88,24 +89,64 @@ public final class GitWorktrees implements Worktrees {
     );
 
     private final String configuredRoot;
+    /** OS group name for {@link #shareWithGroup} (fleetd #185 stage 3); {@code null} ⇒ feature off. */
+    private final String group;
     private final Consumer<String> afterWorktreeAdded;
+    /** How {@link #shareWithGroup}'s processes (git config / chgrp / chmod / find) actually run.
+     *  Defaults to the real {@link #exec(String...)}. Package-private test seam so a unit test can
+     *  prove "no group configured ⇒ zero processes spawned" and inspect exactly what a configured
+     *  group runs, without a real second OS user or OS group on this host. */
+    private final Function<String[], String> shareGroupRunner;
     private final SecureRandom random = new SecureRandom();
     private final AtomicLong seq = new AtomicLong();
 
     /** Default constructor: worktree root is derived per-repo as {@code <repoRoot>/../.bridged-worktrees}. */
     public GitWorktrees() {
-        this(null);
+        this(null, (String) null);
     }
 
-    /** @param configuredRoot nullable absolute or relative path; null/blank derives a sibling of the repo root. */
+    /**
+     * @param configuredRoot nullable absolute or relative path; null/blank derives a sibling of
+     *                       the repo root. No {@code worktreeGroup} configured — {@link #shareWithGroup}
+     *                       is a no-op.
+     */
     public GitWorktrees(String configuredRoot) {
-        this(configuredRoot, _ -> {});
+        this(configuredRoot, (String) null);
+    }
+
+    /**
+     * @param configuredRoot nullable absolute or relative path; null/blank derives a sibling of
+     *                       the repo root.
+     * @param group          optional OS group name (fleetd #185 stage 3, {@code worktreeGroup:} in
+     *                       config); null/blank ⇒ {@link #shareWithGroup} is a no-op.
+     */
+    public GitWorktrees(String configuredRoot, String group) {
+        this(configuredRoot, group, _ -> {});
     }
 
     /** Test seam for changing a real worktree between its creation and its security check. */
     GitWorktrees(String configuredRoot, Consumer<String> afterWorktreeAdded) {
+        this(configuredRoot, null, afterWorktreeAdded);
+    }
+
+    /** Test seam combining a configurable {@code group} with {@link #afterWorktreeAdded}. */
+    GitWorktrees(String configuredRoot, String group, Consumer<String> afterWorktreeAdded) {
+        this(configuredRoot, group, afterWorktreeAdded, null);
+    }
+
+    /**
+     * Full test seam: also overrides how {@link #shareWithGroup}'s processes run (fleetd #185
+     * stage 3), so a unit test can prove "no group configured ⇒ no process spawned" and inspect
+     * exactly what commands a configured group runs, without a real second OS user/group.
+     *
+     * @param shareGroupRunner {@code null} ⇒ the real {@link #exec(String...)}.
+     */
+    GitWorktrees(String configuredRoot, String group, Consumer<String> afterWorktreeAdded,
+                 Function<String[], String> shareGroupRunner) {
         this.configuredRoot = configuredRoot;
+        this.group = (group == null || group.isBlank()) ? null : group;
         this.afterWorktreeAdded = afterWorktreeAdded == null ? _ -> {} : afterWorktreeAdded;
+        this.shareGroupRunner = shareGroupRunner != null ? shareGroupRunner : this::exec;
     }
 
     @Override
@@ -607,6 +648,126 @@ public final class GitWorktrees implements Worktrees {
         return deleted;
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * <p>fleetd #185 stage 3. No-op — no process spawned, nothing logged — when {@link #group} is
+     * null/blank. Otherwise:
+     * <ol>
+     *   <li>{@code git -C repoRoot config core.sharedRepository group} so every future write by
+     *       either uid stays group-writable;</li>
+     *   <li>a one-time {@code chgrp}/{@code chmod g+rwX} fix-up over the worktree directory and,
+     *       under the repo's <em>common</em> git directory, {@code objects}, {@code refs},
+     *       {@code logs}, {@code worktrees} and {@code packed-refs} — with setgid
+     *       ({@code chmod g+s}) applied only to the directories among them, so files created later
+     *       inherit the group;</li>
+     *   <li>one INFO line naming the group and the paths touched.</li>
+     * </ol>
+     *
+     * <p><b>Every path is skipped when it does not exist.</b> {@code .git/logs} is absent in a repo
+     * with {@code core.logAllRefUpdates=false} or one that has had no ref update yet, and
+     * {@code packed-refs} is absent until refs are packed. Passing a missing path to {@code chgrp}
+     * exits non-zero, which would fail <em>every</em> provisioning spawn with a message blaming a
+     * group that is in fact fine.
+     *
+     * <p><b>The git directory is resolved, not assumed.</b> {@code <repoRoot>/.git} is a
+     * <em>file</em>, not a directory, when the checkout is itself a linked worktree — the very
+     * thing this class creates for every member. {@code git rev-parse --git-common-dir} gives the
+     * real shared store, and it may answer relatively, so it is resolved against {@code repoRoot}.
+     *
+     * <p><b>The fix-up re-runs on every spawn, by design.</b> {@code core.sharedRepository=group}
+     * governs only what git writes <em>after</em> it is set; the walk is what covers everything
+     * already on disk. It is not redundant work to optimise away — dropping it silently leaves
+     * pre-existing objects unreadable to the member. It costs three walks of the object store per
+     * spawn (about 3000 files in this repo, well under a second, but it grows with the repo).
+     *
+     * <p>This only fixes up file ownership/permissions on the operator's shared repo so a
+     * different-uid member can write to it — it isolates credentials, not the repository. A member
+     * in the group can still write the operator's git objects and refs.
+     *
+     * <p>Fails loudly: a missing group, or a {@code chgrp}/{@code chmod} refused because the
+     * operator is not a member of it, becomes a {@link WorktreeException} naming the group — never
+     * a silent skip that leaves a member unable to work with nothing in the log to explain why.
+     */
+    @Override
+    public void shareWithGroup(String repoRoot, String worktreePath) {
+        if (group == null) {
+            return;
+        }
+        List<String> touched = new ArrayList<>();
+        try {
+            shareGroupRunner.apply(new String[]{"git", "-C", repoRoot, "config", "core.sharedRepository", "group"});
+            String commonDir = gitCommonDir(repoRoot);
+            shareGroupPathIfPresent(worktreePath, true, touched);
+            for (String name : List.of("objects", "refs", "logs", "worktrees")) {
+                shareGroupPathIfPresent(commonDir + "/" + name, true, touched);
+            }
+            shareGroupPathIfPresent(commonDir + "/packed-refs", false, touched);
+        } catch (WorktreeException e) {
+            throw new WorktreeException("cannot share worktree with group '" + group + "': "
+                    + e.getMessage() + " — the group must exist, and the fleetd operator ("
+                    + System.getProperty("user.name") + ") must be a member of it", e);
+        }
+        log.info("worktreeGroup={} shared repoRoot={} worktreePath={} paths={}",
+                group, repoRoot, worktreePath, touched);
+    }
+
+    /**
+     * The repo's <em>common</em> git directory as an absolute path — where {@code objects},
+     * {@code refs} and {@code worktrees} actually live. {@code git rev-parse --git-common-dir}
+     * answers relative to {@code repoRoot} in the ordinary case ({@code .git}) and absolutely for a
+     * linked worktree, so the answer is resolved against {@code repoRoot} either way. Never
+     * hardcode {@code repoRoot + "/.git"}: that is a FILE when the checkout is itself a linked
+     * worktree.
+     */
+    private String gitCommonDir(String repoRoot) {
+        String answer = shareGroupRunner.apply(
+                new String[]{"git", "-C", repoRoot, "rev-parse", "--git-common-dir"});
+        String trimmed = answer == null ? "" : answer.trim();
+        if (trimmed.isEmpty()) {
+            trimmed = ".git";
+        }
+        return Path.of(repoRoot).resolve(trimmed).normalize().toString();
+    }
+
+    /**
+     * {@link #shareGroupPath} when {@code path} exists, recording it in {@code touched}; otherwise
+     * nothing at all. A missing path is normal, not an error — see {@link #shareWithGroup}'s
+     * javadoc for which ones are routinely absent and why passing them to {@code chgrp} would fail
+     * every spawn.
+     */
+    private void shareGroupPathIfPresent(String path, boolean recursive, List<String> touched) {
+        if (!Files.exists(Path.of(path))) {
+            return;
+        }
+        shareGroupPath(path, recursive);
+        touched.add(path);
+    }
+
+    /**
+     * {@code chgrp}/{@code chmod g+rwX} {@code path} to {@link #group}. When {@code recursive},
+     * also walks the directories under {@code path} (including {@code path} itself, when it is a
+     * directory) and sets setgid on each — directories only, per the javadoc on
+     * {@link #shareWithGroup}.
+     */
+    private void shareGroupPath(String path, boolean recursive) {
+        List<String> chgrp = new ArrayList<>(List.of("chgrp"));
+        if (recursive) chgrp.add("-R");
+        chgrp.add(group);
+        chgrp.add(path);
+        shareGroupRunner.apply(chgrp.toArray(new String[0]));
+
+        List<String> chmod = new ArrayList<>(List.of("chmod"));
+        if (recursive) chmod.add("-R");
+        chmod.add("g+rwX");
+        chmod.add(path);
+        shareGroupRunner.apply(chmod.toArray(new String[0]));
+
+        if (recursive) {
+            shareGroupRunner.apply(new String[]{"find", path, "-type", "d", "-exec", "chmod", "g+s", "{}", "+"});
+        }
+    }
+
     /**
      * Every {@code refs/wip/*} ref (see {@link WipRef}). The committer date is read as a unix
      * count of seconds and converted to millis. {@code %00} (NUL) separates the fields because a

fleetd/src/main/java/dev/ltms/fleet/session/SessionManager.java

@@ -472,6 +472,10 @@ public final class SessionManager implements TurnListener {
         try {
             path = worktrees.add(repoRoot, branch, wt.baseRef());
             worktrees.overlayParity(repoRoot, path, launcher.parityOverlay(preResolvedProfile));
+            // fleetd #185 stage 3: MUST run after overlayParity, not folded into add() — overlayParity
+            // copies more files into the worktree after add() returns, so sharing the group any earlier
+            // leaves those overlay files operator-owned and read-only for a different-uid member.
+            worktrees.shareWithGroup(repoRoot, path);
             handle = launcher.spawn(new SpawnRequest(profile, path, callerCwd, sessionName, resumeSessionId, memberRole));
         } catch (RuntimeException e) {
             log.warn("spawn failed for profile={} role={} branch={} path={}: {}",

fleetd/src/main/java/dev/ltms/fleet/session/Worktrees.java

@@ -98,4 +98,21 @@ public interface Worktrees {
     /** CB-586: the operator-visible census of {@code refs/wip/*} in one repository. */
     record WipRefStats(int count, long costBytes) {
     }
+
+    /**
+     * Make {@code repoRoot}'s git store and {@code worktreePath} writable by the configured group
+     * (fleetd #185 stage 3), so a member spawned as a different OS user (see
+     * {@code memberHerdrSocket}) can write its own worktree, its per-worktree git metadata, and
+     * its own commit objects. No-op when no group is configured.
+     *
+     * <p><strong>This isolates credentials, not the repository.</strong> A member in the group can
+     * still write the operator's git objects and refs in the shared repo — this only fixes file
+     * ownership/permissions so a different-uid member can work at all, it grants no narrower access
+     * than that.
+     *
+     * @param repoRoot     the repository whose git store ({@code .git/objects}, {@code refs},
+     *                     {@code logs}, {@code worktrees}, {@code packed-refs}) needs sharing
+     * @param worktreePath the linked worktree's own directory
+     */
+    void shareWithGroup(String repoRoot, String worktreePath);
 }

fleetd/src/test/java/dev/ltms/fleet/config/FleetConfigTest.java

@@ -1036,6 +1036,35 @@ class FleetConfigTest {
         assertEquals(LeadMailbox.DEFAULT_PREFETCH, noEnv.prefetchOrDefault());
     }
 
+    @Test
+    void absentWorktreeGroupLeavesItNull(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("no-worktree-group.yaml");
+        Files.writeString(f, "bind:\n  port: 8080\n");
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertNull(cfg.worktreeGroup(), "no worktreeGroup: key → null → GitWorktrees.shareWithGroup is a no-op");
+    }
+
+    @Test
+    void worktreeGroupKeyParses(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("worktree-group.yaml");
+        Files.writeString(f, "bind:\n  port: 8080\nworktreeGroup: fleet-workers\n");
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertEquals("fleet-workers", cfg.worktreeGroup());
+    }
+
+    @Test
+    void absentWorktreeGroupSurvivesTheBackCompatConstructorChain() {
+        // fleetd #185 stage 3: withDefaults() (and every pre-existing call site) must not silently
+        // drop a live worktreeGroup by routing through a back-compat constructor that defaults it
+        // to null.
+        FleetConfig cfg = new FleetConfig(null, null, null, Map.of(), null, null, null, null, null,
+                null, null, null, null, null, null, null, null, null, null, null, "fleet-workers");
+        assertEquals("fleet-workers", cfg.withDefaults().worktreeGroup(),
+                "withDefaults() must carry a configured worktreeGroup through unchanged");
+    }
+
     @Test
     void absentPrimaryBlockLeavesPrimaryNull(@TempDir Path dir) throws Exception {
         Path f = dir.resolve("no-primary.yaml");

fleetd/src/test/java/dev/ltms/fleet/herdr/FakeParentResolver.java

@@ -0,0 +1,27 @@
+package dev.ltms.fleet.herdr;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.OptionalLong;
+
+/**
+ * Fake {@link ParentResolver} backed by an explicit pid→parent map — lets {@link PaneLocatorTest}
+ * drive {@link PaneLocator}'s ancestry walk (grandchild pids, cycles) without spawning real OS
+ * processes.
+ */
+final class FakeParentResolver implements ParentResolver {
+
+    private final Map<Long, Long> parents = new HashMap<>();
+
+    /** {@code pid}'s parent is {@code parentPid}. A pid with no entry here has no known parent. */
+    FakeParentResolver parent(long pid, long parentPid) {
+        parents.put(pid, parentPid);
+        return this;
+    }
+
+    @Override
+    public OptionalLong parentOf(long pid) {
+        Long parent = parents.get(pid);
+        return parent == null ? OptionalLong.empty() : OptionalLong.of(parent);
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/herdr/PaneLocatorTest.java

@@ -1,7 +1,11 @@
 package dev.ltms.fleet.herdr;
 
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.Test;
 
+import java.util.concurrent.atomic.AtomicInteger;
+
 import static org.junit.jupiter.api.Assertions.*;
 
 /** Unit tests for PID → pane resolution (the herdr half of connection-based MCP identity). */
@@ -63,4 +67,123 @@ class PaneLocatorTest {
         long paneListCalls = shared.calls.stream().filter(c -> c.method().equals("pane.list")).count();
         assertEquals(1, paneListCalls, "same-object lead/member must scan exactly once, not twice");
     }
+
+    // --- ancestry walk (CB-161: grandchild pids matched no pane, resolving as primary) --------
+
+    @Test
+    void stillResolvesAPidThatIsExactlyThePaneShellPid() {
+        // Regression: a pid with no parent chain at all — no ancestry walk is needed to match it.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        PaneLocator loc = new PaneLocator(pane, new FakeParentResolver());
+        assertEquals("term_x", loc.terminalForPid(5000));
+    }
+
+    @Test
+    void stillResolvesAPidThatIsExactlyAForegroundPid() {
+        // Regression: same as above, but matching via the foreground-processes list.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        PaneLocator loc = new PaneLocator(pane, new FakeParentResolver());
+        assertEquals("term_x", loc.terminalForPid(6000));
+    }
+
+    @Test
+    void resolvesAGrandchildPidTwoLevelsBelowTheShellPid() {
+        // The bug: a helper process a worker spawns (python3, curl, ...) is a grandchild of the
+        // pane's shell — not the shell_pid and not a foreground pid directly. Before the fix,
+        // paneOwnsPid only checked direct pid equality, so this pid matched no pane and the
+        // caller fell through to loopback-trust as the primary.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        FakeParentResolver parents = new FakeParentResolver()
+                .parent(7002, 7001)   // grandchild -> child
+                .parent(7001, 5000);  // child -> shell (the pane's shell_pid)
+        PaneLocator loc = new PaneLocator(pane, parents);
+        assertEquals("term_x", loc.terminalForPid(7002));
+    }
+
+    @Test
+    void nullForAPidWhoseAncestryMatchesNoPane() {
+        // Must not break the other direction: a pid that truly belongs to nothing here (e.g. the
+        // real primary) must still resolve to null. Resolving everything to a worker would demote
+        // the actual lead and refuse every orchestration call.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        FakeParentResolver parents = new FakeParentResolver()
+                .parent(9002, 9001)
+                .parent(9001, 9000); // chain never reaches 5000 or 6000
+        PaneLocator loc = new PaneLocator(pane, parents);
+        assertNull(loc.terminalForPid(9002));
+    }
+
+    @Test
+    void ancestryWalkTerminatesOnACycleInsteadOfHanging() {
+        // A fake (or corrupted) parent map that cycles must not hang identity resolution, which
+        // runs on every MCP call. The walk must still terminate and correctly resolve to null.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        FakeParentResolver parents = new FakeParentResolver()
+                .parent(100, 101)
+                .parent(101, 100); // cycle, never reaches the pane's pids
+        PaneLocator loc = new PaneLocator(pane, parents);
+        assertNull(loc.terminalForPid(100));
+    }
+
+    @Test
+    void ancestrySetIsComputedOnceAcrossBothClientsInTheTwoDaemonConstructor() {
+        // CB-185: the two-daemon constructor searches lead then member. The ancestor set is
+        // per-caller, not per-client — it must be walked once and reused, not recomputed for
+        // each client searched.
+        OnePaneHerdr pane = new OnePaneHerdr("term_x", "pX", 5000, 6000);
+        FakeParentResolver parents = new FakeParentResolver()
+                .parent(7002, 7001)
+                .parent(7001, 5000);
+        AtomicInteger calls = new AtomicInteger();
+        ParentResolver counting = pid -> {
+            calls.incrementAndGet();
+            return parents.parentOf(pid);
+        };
+        HerdrClient noPanes = new FakeHerdr().withNoPanes();
+        PaneLocator two = new PaneLocator(noPanes, pane, counting);
+        assertEquals("term_x", two.terminalForPid(7002));
+        assertEquals(3, calls.get(), "ancestry must be walked once (3 lookups: 7002, 7001, 5000), "
+                + "not re-walked per herdr client");
+    }
+
+    /** Minimal single-pane {@link HerdrClient} fake, purpose-built for the ancestry tests above. */
+    private static final class OnePaneHerdr implements HerdrClient {
+        private final ObjectMapper mapper = new ObjectMapper();
+        private final String terminalId;
+        private final String paneId;
+        private final long shellPid;
+        private final long foregroundPid;
+
+        OnePaneHerdr(String terminalId, String paneId, long shellPid, long foregroundPid) {
+            this.terminalId = terminalId;
+            this.paneId = paneId;
+            this.shellPid = shellPid;
+            this.foregroundPid = foregroundPid;
+        }
+
+        @Override
+        public JsonNode call(String method, Object params) {
+            try {
+                return switch (method) {
+                    case "pane.list" -> mapper.readTree(("""
+                            {"type":"pane_list","panes":[
+                              {"pane_id":"%s","terminal_id":"%s","workspace_id":"w1","tab_id":"w1:t1","agent":"claude"}]}""")
+                            .formatted(paneId, terminalId));
+                    case "pane.process_info" -> mapper.readTree(("""
+                            {"type":"pane_process_info","process_info":{"pane_id":"%s","shell_pid":%d,
+                              "foreground_processes":[{"pid":%d,"name":"node","argv0":"claude"}]}}""")
+                            .formatted(paneId, shellPid, foregroundPid));
+                    default -> throw new HerdrException("OnePaneHerdr has no canned response for " + method);
+                };
+            } catch (HerdrException e) {
+                throw e;
+            } catch (Exception e) {
+                throw new HerdrException("OnePaneHerdr decode failed for " + method, e);
+            }
+        }
+
+        @Override
+        public void close() {
+        }
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/member/HerdrPeerLauncherAllowListWiringTest.java

@@ -161,6 +161,34 @@ class HerdrPeerLauncherAllowListWiringTest {
                         + "it under allow: — sshAuthSock is unset here, so it defaults to block");
     }
 
+    @Test
+    void brokerUriEnvStaysBlockedWhenListedInMemberCredentialsAllow() {
+        FakeHerdr herdr = new FakeHerdr();
+        WiringLauncher launcher = new WiringLauncher(herdr,
+                allowListWithAllow(List.of("BROKER_CONNECTION_URI")), "/bin/zsh", null,
+                () -> config("BROKER_CONNECTION_URI"));
+
+        launcher.spawn(new SpawnRequest("test", null, null, null, null, MemberRole.DEV));
+
+        Path dir = Path.of(launcher.env.get("ZDOTDIR"));
+        assertFalse(readAll(dir.resolve(EnvAllowListScrub.SCRUB_FILE)).contains("'BROKER_CONNECTION_URI'"),
+                "broker.uriEnv must not reach a member even when listed in memberCredentials.allow:");
+    }
+
+    @Test
+    void brokerUriEnvIsDeniedUnderTheDenyListPolicyEvenWhenAllowed() {
+        FakeHerdr herdr = new FakeHerdr();
+        WiringLauncher launcher = new WiringLauncher(herdr,
+                () -> new FleetConfig.MemberCredentials(null, List.of("BROKER_CONNECTION_URI"), List.of(), null),
+                "/bin/bash", null,
+                () -> config("BROKER_CONNECTION_URI"));
+
+        launcher.spawn(new SpawnRequest("test", null, null, null, null, MemberRole.DEV));
+
+        assertEquals("blocked-by-fleetd-cb596-see-gitea-issue-82", launcher.env.get("BROKER_CONNECTION_URI"),
+                "the deny-list overlay must deny broker.uriEnv even when allow: names it");
+    }
+
     /**
      * CB-633 follow-up criterion 3: on every allow-list spawn the daemon logs one INFO line, shaped
      * "member credentials: allowed N of M", with real counts — not constants. Real path: the count
@@ -260,15 +288,24 @@ class HerdrPeerLauncherAllowListWiringTest {
 
         /** Plus an injectable {@code hostEnvNames} source, for the "allowed N of M" log line test. */
         WiringLauncher(FakeHerdr herdr, Supplier<FleetConfig.MemberCredentials> creds, String shell,
-                      Supplier<Set<String>> hostEnvNames) {
+                       Supplier<Set<String>> hostEnvNames) {
+            this(herdr, creds, shell, hostEnvNames, null);
+        }
+
+        WiringLauncher(FakeHerdr herdr, Supplier<FleetConfig.MemberCredentials> creds, String shell,
+                       Supplier<Set<String>> hostEnvNames, Supplier<FleetConfig> config) {
             super("test", new AgentControl(herdr), new WorkspaceControl(herdr),
                     Map.of("test", profile()), "test",
                     name -> "SHELL".equals(name) ? shell : null,
-                    0, () -> 0L, () -> { }, null, creds, hostEnvNames);
+                    0, () -> 0L, () -> { }, null, creds, hostEnvNames, config);
         }
 
         @Override
         protected Launch buildLaunch(FleetConfig.Profile cfg, LaunchSpec spec) {
+            Map<String, String> launchEnv = baseEnv(cfg);
+            launchEnv.putAll(env);
+            env.clear();
+            env.putAll(launchEnv);
             return new Launch(env, List.of("test"));
         }
 
@@ -278,6 +315,12 @@ class HerdrPeerLauncherAllowListWiringTest {
         }
     }
 
+    private static FleetConfig config(String brokerUriEnv) {
+        return new FleetConfig(null, null, null, Map.of(), null, null, null, null, null,
+                new FleetConfig.Broker(null, brokerUriEnv, null), null, null, null, null, null,
+                null, null, null, null, null).withDefaults();
+    }
+
     /** The generated directory is a temp directory; make sure the test does not leave a pile. */
     @Test
     void theGeneratedDirectoryIsRemovedWhenThePaneIsStopped() {

fleetd/src/test/java/dev/ltms/fleet/member/MemberEnvAllowListTest.java

@@ -121,6 +121,34 @@ class MemberEnvAllowListTest {
         assertTrue(derived.contains("OTHER_NAME"), "other allow: names are unaffected");
     }
 
+    @Test
+    void configuredBrokerAndCoordinatorUriEnvNamesAreExcludedEvenWhenAllowed() {
+        FleetConfig config = config("BROKER_CONNECTION_URI", "COORDINATOR_CONNECTION_URI");
+        Set<String> excluded = MemberEnvAllowList.brokerUriEnvNames(config);
+
+        Set<String> derived = MemberEnvAllowList.derive(List.of(),
+                Set.of("BROKER_CONNECTION_URI", "COORDINATOR_CONNECTION_URI", "OTHER_NAME"), excluded);
+
+        assertFalse(derived.contains("BROKER_CONNECTION_URI"),
+                "broker.uriEnv is secret-bearing and must not ride in on allow:");
+        assertFalse(derived.contains("COORDINATOR_CONNECTION_URI"),
+                "coordinator.uriEnv has the same inline-password shape");
+        assertTrue(derived.contains("OTHER_NAME"), "unrelated allow: entries are unaffected");
+    }
+
+    @Test
+    void absentOrBlankBrokerUriEnvAddsNoExclusions() {
+        assertTrue(MemberEnvAllowList.brokerUriEnvNames(config(null, null)).isEmpty());
+        assertTrue(MemberEnvAllowList.brokerUriEnvNames(config(" ", "")).isEmpty());
+    }
+
+    private static FleetConfig config(String brokerUriEnv, String coordinatorUriEnv) {
+        return new FleetConfig(null, null, null, Map.of(), null, null, null, null, null,
+                new FleetConfig.Broker(null, brokerUriEnv, null), null, null, null, null, null,
+                null, null, null, null,
+                new FleetConfig.Coordinator(null, coordinatorUriEnv, null, null)).withDefaults();
+    }
+
     /** {@code LC_*} categories are infrastructure by prefix; everything else needs an exact match. */
     @Test
     void keepsMatchesExactlyPlusTheLocalePrefixRule() {

fleetd/src/test/java/dev/ltms/fleet/msg/MessageServiceTest.java

@@ -710,6 +710,68 @@ class MessageServiceTest {
         assertEquals(MessageService.Outcome.REPLIED, answer.get(5, TimeUnit.SECONDS).outcome());
     }
 
+    // --- #137: a fleet_ask round-trip must not orphan the ticket's own reply -------------------
+    //
+    // The primary's fleet_send{turnId} answer call is itself bounded (a real MCP call, capped well
+    // under a minute) — far shorter than a resumed turn can genuinely take to finish real work. These
+    // drive the exact real delegation path (async send -> worker asks -> primary answers -> primary's
+    // own wait gives up -> worker's real fleet_reply arrives afterwards) rather than calling a reply
+    // sink directly, since the bug is specifically about which sink the resumed turn's reply reaches.
+
+    @Test
+    void aReplyAfterAnswerTimesOutStillCompletesTheAsyncTicket() throws Exception {
+        String ticket = messages.sendAsync(T, "task that asks");
+        awaitWaiting();
+        injectDelivery();
+
+        CompletableFuture<MessageService.AskResult> ask =
+                CompletableFuture.supplyAsync(() -> messages.ask(T, "which config?", 5000));
+        MessageService.TaskView asking = awaitTicketPhase(ticket, MessageService.Phase.ASKING);
+
+        // The primary answers, but its own bounded wait for the worker's resumed turn is short and
+        // expires before the worker (still genuinely working) gets back to it.
+        MessageService.Reply answerReply = messages.answer(asking.turnId(), "config.yaml", 150);
+        assertEquals("config.yaml", ask.get(5, TimeUnit.SECONDS).answer());
+        assertEquals(MessageService.Outcome.TIMED_OUT_WORKING, answerReply.outcome(),
+                "the primary's own bounded wait gives up before the worker finishes resuming");
+
+        // The worker keeps working past that window and only now calls fleet_reply.
+        assertTrue(messages.reply(T, "PR opened: https://example/pulls/42"));
+
+        MessageService.TaskView done = awaitTicketPhase(ticket, MessageService.Phase.DONE);
+        assertEquals("PR opened: https://example/pulls/42", done.reply(),
+                "fleet_poll{ticket} must return the worker's real reply, not stay pending forever");
+        assertEquals("reply", done.replySource());
+        assertFalse(messages.hasStrandedReply(T),
+                "the reply completed its own ticket directly and never touched the inbox");
+    }
+
+    @Test
+    void fleetStopAfterAnOrphanedReplyDoesNotFailTheTicket() throws Exception {
+        String ticket = messages.sendAsync(T, "task that asks");
+        awaitWaiting();
+        injectDelivery();
+
+        CompletableFuture<MessageService.AskResult> ask =
+                CompletableFuture.supplyAsync(() -> messages.ask(T, "which config?", 5000));
+        MessageService.TaskView asking = awaitTicketPhase(ticket, MessageService.Phase.ASKING);
+
+        MessageService.Reply answerReply = messages.answer(asking.turnId(), "config.yaml", 150);
+        assertEquals("config.yaml", ask.get(5, TimeUnit.SECONDS).answer());
+        assertEquals(MessageService.Outcome.TIMED_OUT_WORKING, answerReply.outcome());
+
+        assertTrue(messages.reply(T, "PR opened: https://example/pulls/42"));
+
+        // fleet_stop tears the worker's session down right after the reply landed — this must never
+        // report the misleading "the worker session was released before it replied": a reply is
+        // exactly what happened.
+        assertFalse(messages.abandon(T, "the worker session was released before it replied"),
+                "a reply already arrived, so nothing here is a genuine failure");
+
+        MessageService.TaskView view = awaitTicketPhase(ticket, MessageService.Phase.DONE);
+        assertEquals("PR opened: https://example/pulls/42", view.reply());
+    }
+
     @Test
     void unansweredAsyncQuestionReturnsTheTicketToPendingAndReleasesItsTarget() throws Exception {
         String ticket = messages.sendAsync(T, "task that asks");

fleetd/src/test/java/dev/ltms/fleet/session/FakeWorktrees.java

@@ -30,12 +30,19 @@ public final class FakeWorktrees implements Worktrees {
     public record PruneCall(String repoRoot, long minAgeMillis) {
     }
 
+    public record ShareCall(String repoRoot, String worktreePath) {
+    }
+
     private final List<AddCall> addCalls = new CopyOnWriteArrayList<>();
     private final List<RemoveCall> removeCalls = new CopyOnWriteArrayList<>();
     private final List<OverlayCall> overlayCalls = new CopyOnWriteArrayList<>();
     private final List<RepoRootCall> repoRootCalls = new CopyOnWriteArrayList<>();
     private final List<SnapshotCall> snapshotCalls = new CopyOnWriteArrayList<>();
     private final List<PruneCall> pruneCalls = new CopyOnWriteArrayList<>();
+    private final List<ShareCall> shareCalls = new CopyOnWriteArrayList<>();
+    /** Tags every {@code overlayParity}/{@code shareWithGroup} call in call order, so a test can
+     *  pin that sharing runs after the overlay copy (fleetd #185 stage 3). */
+    private final List<String> overlayShareOrder = new CopyOnWriteArrayList<>();
     private final Set<String> existingPaths = ConcurrentHashMap.newKeySet();
     private final Set<String> trackedPaths = ConcurrentHashMap.newKeySet();
     private final AtomicLong snapshotSeq = new AtomicLong();
@@ -136,6 +143,13 @@ public final class FakeWorktrees implements Worktrees {
         }
         overlayCalls.add(new OverlayCall(repoRoot, worktreePath, List.copyOf(overlay),
                 List.copyOf(copied), List.copyOf(skipped)));
+        overlayShareOrder.add("overlay:" + worktreePath);
+    }
+
+    @Override
+    public void shareWithGroup(String repoRoot, String worktreePath) {
+        shareCalls.add(new ShareCall(repoRoot, worktreePath));
+        overlayShareOrder.add("share:" + worktreePath);
     }
 
     @Override
@@ -203,4 +217,17 @@ public final class FakeWorktrees implements Worktrees {
     public SnapshotCall lastSnapshot() {
         return snapshotCalls.isEmpty() ? null : snapshotCalls.getLast();
     }
+
+    public List<ShareCall> shareCalls() {
+        return List.copyOf(shareCalls);
+    }
+
+    public ShareCall lastShare() {
+        return shareCalls.isEmpty() ? null : shareCalls.getLast();
+    }
+
+    /** Call-order tags ({@code "overlay:<path>"}/{@code "share:<path>"}) — see field javadoc. */
+    public List<String> overlayShareOrder() {
+        return List.copyOf(overlayShareOrder);
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/session/GitWorktreesTest.java

@@ -924,4 +924,179 @@ class GitWorktreesTest {
         assertEquals(2, stats.count(), "two snapshot refs are reported");
         assertTrue(stats.costBytes() > 0, "the cost of the snapshots is a positive byte count");
     }
+
+    /**
+     * fleetd #185 stage 3: a recording {@link java.util.function.Function} test seam stands in for
+     * every process {@link GitWorktrees#shareWithGroup} would run — no real second OS user/group
+     * exists on this host, so these are unit tests against that seam, not a live-group integration
+     * test (out of scope per the ticket).
+     */
+    private static List<String> joined(String[] command) {
+        return List.of(command);
+    }
+
+    /** Remove {@code path} and anything under it. Tolerates an already-absent path. */
+    private static void deleteRecursively(Path path) throws Exception {
+        if (!Files.exists(path)) {
+            return;
+        }
+        if (Files.isDirectory(path)) {
+            try (java.util.stream.Stream<Path> children = Files.list(path)) {
+                for (Path child : children.toList()) {
+                    deleteRecursively(child);
+                }
+            }
+        }
+        Files.delete(path);
+    }
+
+    /** {@code worktreeGroup} absent ⇒ zero processes spawned and no git config written. */
+    @Test
+    void shareWithGroupIsNoopWhenNoGroupConfigured(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        List<List<String>> recorded = new java.util.ArrayList<>();
+        java.util.function.Function<String[], String> recordingRunner = cmd -> {
+            recorded.add(joined(cmd));
+            return "";
+        };
+        GitWorktrees gitWorktrees = new GitWorktrees(tmp.resolve("wts").toString(), null, _ -> {}, recordingRunner);
+
+        gitWorktrees.shareWithGroup(repo.toString(), repo.resolve("some-worktree").toString());
+
+        assertTrue(recorded.isEmpty(), "no group configured must spawn no process at all: " + recorded);
+    }
+
+    /** A configured group runs {@code git config core.sharedRepository group} first, then
+     *  chgrp/chmod/setgid over every path {@link GitWorktrees#shareWithGroup} documents. */
+    @Test
+    void shareWithGroupRunsConfigThenChgrpChmodSetgidPerPath(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        String repoRoot = repo.toString();
+        Path worktree = Files.createDirectories(repo.resolve("some-worktree"));
+        String worktreePath = worktree.toString();
+        Files.createDirectories(repo.resolve(".git/worktrees"));
+        List<List<String>> recorded = new java.util.ArrayList<>();
+        java.util.function.Function<String[], String> recordingRunner = cmd -> {
+            recorded.add(joined(cmd));
+            // What real git answers for an ordinary (non-linked) checkout: relative to repoRoot.
+            return List.of(cmd).contains("--git-common-dir") ? ".git\n" : "";
+        };
+        GitWorktrees gitWorktrees =
+                new GitWorktrees(tmp.resolve("wts").toString(), "devteam", _ -> {}, recordingRunner);
+
+        gitWorktrees.shareWithGroup(repoRoot, worktreePath);
+
+        assertEquals(List.of("git", "-C", repoRoot, "config", "core.sharedRepository", "group"), recorded.get(0),
+                "core.sharedRepository must be set first, so it keeps working after the one-time fix-up");
+        assertTrue(recorded.contains(List.of("git", "-C", repoRoot, "rev-parse", "--git-common-dir")),
+                "the git dir must be asked for, never hardcoded as <repoRoot>/.git — that is a FILE "
+                        + "when the checkout is itself a linked worktree: " + recorded);
+
+        for (String dir : List.of(worktreePath, repoRoot + "/.git/objects", repoRoot + "/.git/refs",
+                repoRoot + "/.git/logs", repoRoot + "/.git/worktrees")) {
+            assertTrue(recorded.contains(List.of("chgrp", "-R", "devteam", dir)), "missing chgrp -R for " + dir);
+            assertTrue(recorded.contains(List.of("chmod", "-R", "g+rwX", dir)), "missing chmod -R for " + dir);
+            assertTrue(recorded.contains(List.of("find", dir, "-type", "d", "-exec", "chmod", "g+s", "{}", "+")),
+                    "missing setgid find pass for " + dir);
+        }
+        // packed-refs does not exist in a freshly-init'd repo (only git gc / pack-refs creates it) —
+        // tolerated absence, so it must not appear at all: no recursive/-R treatment for a plain file.
+        String packedRefs = repoRoot + "/.git/packed-refs";
+        assertTrue(recorded.stream().noneMatch(c -> c.contains(packedRefs)),
+                "packed-refs is absent here and must be skipped, not chgrp'd: " + recorded);
+    }
+
+    /**
+     * A path that does not exist is skipped, never handed to {@code chgrp}. {@code .git/logs} is
+     * absent whenever {@code core.logAllRefUpdates} is false or no ref has been updated yet, and
+     * {@code chgrp} on a missing path exits non-zero — which would fail EVERY provisioning spawn
+     * with a message blaming a group that is in fact fine.
+     */
+    @Test
+    void shareWithGroupSkipsPathsThatDoNotExist(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        String repoRoot = repo.toString();
+        deleteRecursively(repo.resolve(".git/logs"));
+        assertFalse(Files.exists(repo.resolve(".git/logs")), "fixture: .git/logs must be gone");
+        List<List<String>> recorded = new java.util.ArrayList<>();
+        java.util.function.Function<String[], String> recordingRunner = cmd -> {
+            recorded.add(joined(cmd));
+            return List.of(cmd).contains("--git-common-dir") ? ".git\n" : "";
+        };
+        GitWorktrees gitWorktrees =
+                new GitWorktrees(tmp.resolve("wts").toString(), "devteam", _ -> {}, recordingRunner);
+
+        gitWorktrees.shareWithGroup(repoRoot, repo.resolve("no-such-worktree").toString());
+
+        String logs = repoRoot + "/.git/logs";
+        assertTrue(recorded.stream().noneMatch(c -> c.contains(logs)),
+                "a missing .git/logs must be skipped, not chgrp'd: " + recorded);
+        assertTrue(recorded.stream().noneMatch(c -> c.contains(repo.resolve("no-such-worktree").toString())),
+                "a missing worktree path must be skipped too: " + recorded);
+        assertTrue(recorded.contains(List.of("chgrp", "-R", "devteam", repoRoot + "/.git/objects")),
+                "paths that DO exist are still shared: " + recorded);
+    }
+
+    /**
+     * The git store is located by {@code rev-parse --git-common-dir}, not by appending
+     * {@code /.git}. When git answers with an absolute path — what it does for a linked worktree,
+     * where {@code <repoRoot>/.git} is a file — every shared path must follow that answer.
+     */
+    @Test
+    void shareWithGroupFollowsAnAbsoluteGitCommonDir(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        Path realGitDir = repo.resolve(".git");
+        List<List<String>> recorded = new java.util.ArrayList<>();
+        java.util.function.Function<String[], String> recordingRunner = cmd -> {
+            recorded.add(joined(cmd));
+            return List.of(cmd).contains("--git-common-dir") ? realGitDir + "\n" : "";
+        };
+        GitWorktrees gitWorktrees =
+                new GitWorktrees(tmp.resolve("wts").toString(), "devteam", _ -> {}, recordingRunner);
+
+        gitWorktrees.shareWithGroup(tmp.resolve("some/linked/worktree").toString(),
+                repo.resolve("wt").toString());
+
+        assertTrue(recorded.contains(List.of("chgrp", "-R", "devteam", realGitDir + "/objects")),
+                "objects must be taken from the reported common dir, not <repoRoot>/.git: " + recorded);
+    }
+
+    /** {@code packed-refs}, when present, is chgrp/chmod'd but never setgid'd (it is a file, not a dir). */
+    @Test
+    void shareWithGroupIncludesPackedRefsWhenPresent(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        String repoRoot = repo.toString();
+        Path packedRefsPath = repo.resolve(".git/packed-refs");
+        Files.writeString(packedRefsPath, "");
+        List<List<String>> recorded = new java.util.ArrayList<>();
+        java.util.function.Function<String[], String> recordingRunner = cmd -> {
+            recorded.add(joined(cmd));
+            return "";
+        };
+        GitWorktrees gitWorktrees =
+                new GitWorktrees(tmp.resolve("wts").toString(), "devteam", _ -> {}, recordingRunner);
+
+        gitWorktrees.shareWithGroup(repoRoot, repo.resolve("some-worktree").toString());
+
+        String packedRefs = packedRefsPath.toString();
+        assertTrue(recorded.contains(List.of("chgrp", "devteam", packedRefs)),
+                "packed-refs must be chgrp'd non-recursively when present: " + recorded);
+        assertTrue(recorded.contains(List.of("chmod", "g+rwX", packedRefs)),
+                "packed-refs must be chmod'd non-recursively when present: " + recorded);
+        assertTrue(recorded.stream().noneMatch(c -> c.contains("find") && c.contains(packedRefs)),
+                "packed-refs (a file) must never get the recursive setgid pass: " + recorded);
+    }
+
+    /** A group that does not exist (or that the operator is not a member of) fails loudly, naming it. */
+    @Test
+    void shareWithGroupThrowsNamingTheGroupWhenChgrpFails(@TempDir Path tmp) throws Exception {
+        Path repo = initRepo(tmp.resolve("repo"));
+        GitWorktrees gitWorktrees = new GitWorktrees(tmp.resolve("wts").toString(), "cb185-nonexistent-group-zz");
+        String wt = new GitWorktrees(tmp.resolve("wts").toString()).add(repo.toString(), "cb-185-share", "HEAD");
+
+        WorktreeException e = assertThrows(WorktreeException.class,
+                () -> gitWorktrees.shareWithGroup(repo.toString(), wt));
+        assertTrue(e.getMessage().contains("cb185-nonexistent-group-zz"),
+                "exception must name the missing/refused group: " + e.getMessage());
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/session/SessionManagerTest.java

@@ -148,6 +148,10 @@ class SessionManagerTest {
             return 0;
         }
 
+        @Override
+        public void shareWithGroup(String repoRoot, String worktreePath) {
+        }
+
         List<String> removeCalls() {
             return List.copyOf(removeCalls);
         }

fleetd/src/test/java/dev/ltms/fleet/session/WorktreeSessionManagerTest.java

@@ -163,6 +163,37 @@ class WorktreeSessionManagerTest {
                 "tracked copied paths are --skip-worktree'd");
     }
 
+    /**
+     * fleetd #185 stage 3, THE TRAP: {@code overlayParity} copies more files into the worktree
+     * AFTER {@code add} returns, so {@code shareWithGroup} must run after it, not folded into
+     * {@code add()} — otherwise every overlay file lands operator-owned and unwritable for a
+     * different-uid member, with a green test suite hiding it.
+     */
+    @Test
+    void shareWithGroupRunsAfterOverlayParityNotBeforeIt() {
+        FakeHerdr herdr = new FakeHerdr();
+        FakeWorktrees worktrees = new FakeWorktrees().withRepoRoot("/repo").withPrefix("/wt")
+                .track(".envrc");
+        SessionManager sessions = new SessionManager(workerService(herdr), worktrees);
+
+        MemberSession s = sessions.acquire("ltms-local", null, "/caller/proj", null,
+                new WorktreeRequest("cb-185", null));
+
+        assertEquals(1, worktrees.overlayCalls().size(), "overlayParity ran exactly once");
+        assertEquals(1, worktrees.shareCalls().size(), "shareWithGroup ran exactly once");
+        FakeWorktrees.OverlayCall overlay = worktrees.lastOverlay();
+        FakeWorktrees.ShareCall share = worktrees.lastShare();
+        assertEquals(s.worktree(), overlay.worktreePath());
+        assertEquals(s.worktree(), share.worktreePath());
+
+        List<String> order = worktrees.overlayShareOrder();
+        int overlayIndex = order.indexOf("overlay:" + s.worktree());
+        int shareIndex = order.indexOf("share:" + s.worktree());
+        assertTrue(overlayIndex >= 0 && shareIndex >= 0, "both calls must be recorded: " + order);
+        assertTrue(overlayIndex < shareIndex,
+                "shareWithGroup MUST run after overlayParity, not before/inside add(): " + order);
+    }
+
     @Test
     void releaseRemovesWorktreeButDoesNotDeleteBranch() {
         FakeHerdr herdr = new FakeHerdr();