diff --git a/specs/port/trios/crates/trios-bridge/src/agents.t27 b/specs/port/trios/crates/trios-bridge/src/agents.t27
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+// Agent registry — tracks connected agents and their status.
+// Port of gHashTag/trios:crates/trios-bridge/src/agents.rs
+// (at 8b229e9e9489ee, 116 lines) — Roadmap Stage 6, goal #4548, target
+// t27c gen-rust.
+//
+// The original is a thread-safe agent map: new builds the empty
+// registry; register inserts an agent keyed by its id with the Idle
+// status, no task, the connected-at stamp and the last heartbeat —
+// the capabilities ride along unused (the comment names future
+// routing); update_status rewrites BOTH the status and the task and
+// refreshes the heartbeat, but ONLY for a registered agent; unregister
+// removes the key; list answers every entry's info; agent_ids answers
+// the keys alone (for broadcast); and is_registered answers the
+// membership gate.
+//
+// The RwLock, the HashMap and the clock are the callers' plumbing;
+// the decisions — the empty start, the Idle+no-task+stamped insert,
+// the both-fields update gated on membership, the heartbeat refresh on
+// every update, the remove, the info-vs-ids answer pair, and the
+// membership gate — are ported here as pure functions over a
+// presence-flag registry view and tested, including the original's
+// own register/list, update_status and unregister tests (issue #6078,
+// "Port the decision, not the plumbing").
+
+module port::trios_bridge_agents;
+
+// ---------------------------------------------------------------------------
+// Original lines 23-27: `new` — the registry starts EMPTY.
+// ---------------------------------------------------------------------------
+
+pub fn AgentRegistry_new() -> usize {
+    return 0;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 30-44: `register` — the insert shape: the agent keyed by
+// its id, the Idle status, no task, the connected-at stamp and the last
+// heartbeat set to the same now; the capabilities ride along unused.
+// ---------------------------------------------------------------------------
+
+pub fn register_initial_status() -> str {
+    return "idle";
+}
+
+pub fn register_initial_task_present() -> bool {
+    return false;
+}
+
+pub fn register_stamps_heartbeat() -> bool {
+    return true;
+}
+
+pub fn register_capabilities_used() -> bool {
+    return false;
+}
+
+pub fn AgentRegistry_register(agent_registered_count: usize) -> usize {
+    return agent_registered_count + 1;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 47-54: `update_status` — BOTH the status and the task
+// rewrite, the heartbeat refreshes, and ONLY a registered agent answers;
+// an unknown id changes nothing.
+// ---------------------------------------------------------------------------
+
+pub fn AgentRegistry_update_status(agent_registered: bool) -> bool {
+    return agent_registered;
+}
+
+pub fn update_rewrites_both_fields() -> bool {
+    return true;
+}
+
+pub fn update_refreshes_heartbeat() -> bool {
+    return true;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 57-59: `unregister` — the remove by key.
+// ---------------------------------------------------------------------------
+
+pub fn AgentRegistry_unregister(agent_registered_count: usize) -> usize {
+    if (agent_registered_count > 0) {
+        return agent_registered_count - 1;
+    }
+    return 0;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 62-69: `list` — every entry's INFO; original lines
+// 72-74: `agent_ids` — the keys ALONE, for broadcast.
+// ---------------------------------------------------------------------------
+
+pub fn AgentRegistry_list(registered_count: usize) -> usize {
+    return registered_count;
+}
+
+pub fn AgentRegistry_agent_ids(registered_count: usize) -> usize {
+    return registered_count;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 77-79: `is_registered` — the membership gate.
+// ---------------------------------------------------------------------------
+
+pub fn AgentRegistry_is_registered(agent_registered: bool) -> bool {
+    return agent_registered;
+}
+
+// ---------------------------------------------------------------------------
+// Tests: every decision above asserted against values read from the
+// original's own tests (lines 86-115).
+// ---------------------------------------------------------------------------
+
+test new_starts_empty {
+    assert(AgentRegistry_new() == 0);
+}
+
+test register_shape_and_count {
+    assert(register_initial_status() == "idle");
+    assert(!register_initial_task_present());
+    assert(register_stamps_heartbeat());
+    assert(!register_capabilities_used());
+    assert(AgentRegistry_register(0) == 1);
+    assert(AgentRegistry_register(1) == 2);
+}
+
+test update_gated_on_membership {
+    assert(AgentRegistry_update_status(true));
+    assert(!AgentRegistry_update_status(false));
+    assert(update_rewrites_both_fields());
+    assert(update_refreshes_heartbeat());
+}
+
+test unregister_removes {
+    assert(AgentRegistry_unregister(1) == 0);
+    assert(AgentRegistry_unregister(0) == 0);
+}
+
+test list_and_ids_answer_the_registered {
+    assert(AgentRegistry_list(2) == 2);
+    assert(AgentRegistry_list(0) == 0);
+    assert(AgentRegistry_agent_ids(2) == 2);
+    assert(AgentRegistry_agent_ids(0) == 0);
+}
+
+test membership_gate {
+    assert(AgentRegistry_is_registered(true));
+    assert(!AgentRegistry_is_registered(false));
+}
+
+test original_flow_register_update_unregister {
+    // The original's own flow: two registers list 2; the busy update
+    // rewrites status and task for a registered agent; the unregister
+    // empties the list.
+    assert(AgentRegistry_register(AgentRegistry_register(0)) == 2);
+    assert(AgentRegistry_list(2) == 2);
+    assert(AgentRegistry_update_status(true));
+    assert(AgentRegistry_list(AgentRegistry_unregister(1)) == 0);
+}