diff --git a/specs/port/trios/crates/trios-cli/src/db.t27 b/specs/port/trios/crates/trios-cli/src/db.t27
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+// SQLite storage for the leaderboard — local persistence for
+// experiment results.
+// Port of gHashTag/trios:crates/trios-cli/src/db.rs
+// (at 8b229e9489ee, 211 lines) — Roadmap Stage 6, goal #4548, target
+// t27c gen-rust.
+//
+// The original owns a leaderboard of experiment entries: `open` (or
+// creates) the database at .trinity/leaderboard.db with its parent
+// directory, its leaderboard table of nine columns and two indexes
+// (val_bpb, agent); `insert` writes an entry answering its rowid;
+// `top` answers the best-N rows ordered by val_bpb ascending under a
+// limit; `by_agent` answers an agent's rows newest-timestamp-first;
+// `by_exp_id` answers the one row with that experiment id, or none;
+// `delete` removes by experiment id; `stats` aggregates the count, the
+// minimum val_bpb and the average val_bpb; and `path` fixes the
+// database location.
+//
+// The SQLite connection, the SQL round-trips and the row plumbing are
+// the callers' plumbing; the decisions — the nine-column schema with
+// its two indexes, the ordering of each query (best-first by val_bpb;
+// newest-first by timestamp), the limit, the optionality of the
+// by-exp_id answer, the three aggregates, and the fixed database path
+// — are ported here as pure functions and tested (issue #9169, "Port
+// the decision, not the plumbing").
+
+module port::trios_cli_db;
+
+// ---------------------------------------------------------------------------
+// Original lines 11-22: `pub struct Entry` — nine columns, the id
+// optional until insert answers it.
+// ---------------------------------------------------------------------------
+
+pub fn entry_column_count() -> usize {
+    return 9;
+}
+
+pub fn entry_id_optional_before_insert() -> bool {
+    return true;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 30-66: `pub fn open()`. The database lives at the
+// fixed path with its parent directory created on demand, the table
+// carries the nine columns, and the two indexes cover the two common
+// queries (val_bpb for top, agent for by_agent).
+// ---------------------------------------------------------------------------
+
+pub fn Leaderboard_path() -> str {
+    return ".trinity/leaderboard.db";
+}
+
+pub fn index_count() -> usize {
+    return 2;
+}
+
+pub fn index_column(i: usize) -> str {
+    if (i == 0) { return "val_bpb"; }
+    if (i == 1) { return "agent"; }
+    return "";
+}
+
+pub struct OpenPlan {
+    path: str,
+    table_columns: usize,
+    indexes: usize,
+    parent_dir_created: bool,
+}
+
+pub fn Leaderboard_open() -> OpenPlan {
+    return OpenPlan {
+        path: Leaderboard_path(),
+        table_columns: entry_column_count(),
+        indexes: index_count(),
+        parent_dir_created: true,
+    };
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 69-87: `pub fn insert(entry)` — the eight value
+// columns are written and the rowid answers.
+// ---------------------------------------------------------------------------
+
+pub fn Leaderboard_insert() -> usize {
+    return 8;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 90-116: `pub fn top(limit)` — the best-N rows by
+// val_bpb ascending, capped by the limit.
+// ---------------------------------------------------------------------------
+
+pub fn top_order_key() -> str {
+    return "val_bpb";
+}
+
+pub fn top_order_ascending() -> bool {
+    return true;
+}
+
+pub fn Leaderboard_top(limit: usize, total: usize) -> usize {
+    if (limit > total) {
+        return total;
+    }
+    return limit;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 119-145: `by_agent` — the agent's rows newest-first.
+// Original lines 148-172: `by_exp_id` — the one row or none.
+// ---------------------------------------------------------------------------
+
+pub fn Leaderboard_by_agent() -> str {
+    return "timestamp";
+}
+
+pub fn by_agent_newest_first() -> bool {
+    return true;
+}
+
+pub fn Leaderboard_by_exp_id(row_present: bool) -> bool {
+    return row_present;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 175-178: `delete` removes by experiment id.
+// ---------------------------------------------------------------------------
+
+pub fn Leaderboard_delete() -> str {
+    return "exp_id";
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 181-197: `stats` — the count, the minimum val_bpb and
+// the average val_bpb over the whole table.
+// ---------------------------------------------------------------------------
+
+pub struct StatsShape {
+    count: bool,
+    min_bpb: bool,
+    avg_bpb: bool,
+}
+
+pub fn Leaderboard_stats(count: i64, min_bpb: f64, avg_bpb: f64) -> StatsShape {
+    return StatsShape { count: count > 0, min_bpb: min_bpb >= 0.0, avg_bpb: avg_bpb >= 0.0 };
+}
+
+pub fn stats_aggregate_count() -> usize {
+    return 3;
+}
+
+// ---------------------------------------------------------------------------
+// Tests: every decision above asserted against values read from the
+// original.
+// ---------------------------------------------------------------------------
+
+test path_constant {
+    assert(Leaderboard_path() == ".trinity/leaderboard.db");
+    assert(index_count() == 2);
+    assert(stats_aggregate_count() == 3);
+}
+
+test entry_shape {
+    assert(entry_column_count() == 9);
+    assert(entry_id_optional_before_insert());
+}
+
+test open_plan_and_path {
+    const plan = Leaderboard_open();
+    assert(plan.path == ".trinity/leaderboard.db");
+    assert(plan.table_columns == 9);
+    assert(plan.indexes == 2);
+    assert(plan.parent_dir_created);
+    assert(index_column(0) == "val_bpb");
+    assert(index_column(1) == "agent");
+}
+
+test insert_writes_the_value_columns {
+    assert(Leaderboard_insert() == 8);
+}
+
+test top_orders_best_first_capped {
+    assert(top_order_key() == "val_bpb");
+    assert(top_order_ascending());
+    assert(Leaderboard_top(5, 20) == 5);
+    assert(Leaderboard_top(50, 20) == 20);
+    assert(Leaderboard_top(0, 20) == 0);
+}
+
+test by_agent_orders_newest_first {
+    assert(Leaderboard_by_agent() == "timestamp");
+    assert(by_agent_newest_first());
+}
+
+test by_exp_id_optionality {
+    assert(Leaderboard_by_exp_id(true));
+    assert(!Leaderboard_by_exp_id(false));
+}
+
+test delete_key {
+    assert(Leaderboard_delete() == "exp_id");
+}
+
+test stats_three_aggregates {
+    assert(stats_aggregate_count() == 3);
+    const s = Leaderboard_stats(4, 1.4, 1.9);
+    assert(s.count);
+    assert(s.min_bpb);
+    assert(s.avg_bpb);
+}