diff --git a/specs/port/trios/crates/trios-trainer/src/ledger.t27 b/specs/port/trios/crates/trios-trainer/src/ledger.t27
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+// Ledger — triplet-validated row emission with embargo block.
+// Port of gHashTag/trios:crates/trios-trainer/src/ledger.rs
+// (at 8b229e9489ee, 165+ lines) — Roadmap Stage 6, goal #4548, target
+// t27c gen-rust.
+//
+// The original emits ledger rows under a triplet contract — every row
+// MUST carry BPB, step, seed, sha, the jsonl row and the gate status —
+// and guards the emission with an embargo block: a SHA on the blocked
+// list answers EmbargoBlocked before anything is written; a NaN BPB or
+// an empty jsonl row answers InvalidTriplet; the serialize and write
+// steps answer their own errors. The default embargo list is empty
+// (the comment names it the place for failed-validation commits), and
+// Default delegates to new. get_commit_sha shells out to
+// `git rev-parse HEAD`, trimming the answer.
+//
+// The filesystem append and the git subprocess are the callers'
+// plumbing; the decisions — the triplet's six fields with the
+// row-carrying validation, the embargo gate FIRST, the NaN/empty
+// InvalidTriplet rule, the empty default list, the delegation, and
+// the git command shape — are ported here as pure functions and
+// tested, including the original's own embargo and triplet tests
+// (issue #7324, "Port the decision, not the plumbing").
+
+module port::trios_trainer_ledger;
+
+// ---------------------------------------------------------------------------
+// Original lines 13-20: `pub struct Triplet` — the six-field contract
+// every ledger row MUST satisfy.
+// ---------------------------------------------------------------------------
+
+pub fn triplet_field_count() -> usize {
+    return 6;
+}
+
+pub fn triplet_field(i: usize) -> str {
+    if (i == 0) { return "bpb"; }
+    if (i == 1) { return "step"; }
+    if (i == 2) { return "seed"; }
+    if (i == 3) { return "sha"; }
+    if (i == 4) { return "jsonl_row"; }
+    if (i == 5) { return "gate_status"; }
+    return "";
+}
+
+// Original lines 24-32: the full row carries the agent and the
+// timestamp on top of the triplet fields.
+pub fn ledger_row_field_count() -> usize {
+    return 8;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 43-56: `EmbargoBlock::new` — the default blocked list
+// is EMPTY (the comment names it the place for failed-validation
+// commits); `is_embargoed` is the membership gate.
+// ---------------------------------------------------------------------------
+
+pub fn EmbargoBlock_new() -> usize {
+    return 0;
+}
+
+pub fn EmbargoBlock_is_embargoed(blocked_count: usize, sha_index: usize) -> bool {
+    // The membership answer: the caller hands the blocked list's size
+    // and the index of the sha within it; a not-found index means
+    // not embargoed.
+    if (sha_index < blocked_count) {
+        return true;
+    }
+    return false;
+}
+
+// Original lines 58-62: `impl Default` — the delegation to new.
+pub fn EmbargoBlock_default() -> usize {
+    return EmbargoBlock_new();
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 67-110: `emit_row` — the emission order: the embargo
+// gate FIRST (an embargoed sha answers EmbargoBlocked before anything
+// is written), then the serialize, then the append, then the triplet
+// validation with the NaN/empty rule. The write itself is the
+// caller's plumbing; the order and the gates are the decisions.
+// ---------------------------------------------------------------------------
+
+pub fn emit_row_order() -> str {
+    return "embargo,serialize,append,validate";
+}
+
+pub fn emit_row(sha_embargoed: bool, bpb_is_nan: bool, jsonl_empty: bool) -> str {
+    if (sha_embargoed) {
+        return "embargo blocked";
+    }
+    if (bpb_is_nan or jsonl_empty) {
+        return "invalid triplet";
+    }
+    return "ok";
+}
+
+// The InvalidTriplet rule of lines 105-107: a NaN bpb OR an empty
+// jsonl row is the violation.
+pub fn triplet_is_invalid(bpb_is_nan: bool, jsonl_empty: bool) -> bool {
+    return bpb_is_nan or jsonl_empty;
+}
+
+pub fn emit_error_kind(i: usize) -> str {
+    if (i == 0) { return "embargo blocked"; }
+    if (i == 1) { return "serialize error"; }
+    if (i == 2) { return "write error"; }
+    if (i == 3) { return "invalid triplet"; }
+    return "";
+}
+
+pub fn emit_error_count() -> usize {
+    return 4;
+}
+
+// The append contract: the ledger opens create+append — rows are only
+// ever appended, never truncated.
+pub fn ledger_opens_append_only() -> bool {
+    return true;
+}
+
+// ---------------------------------------------------------------------------
+// Original lines 128-140: `get_commit_sha` — `git rev-parse HEAD`,
+// the answer trimmed; a failing command answers the error.
+// ---------------------------------------------------------------------------
+
+pub fn get_commit_sha_command() -> str {
+    return "git rev-parse HEAD";
+}
+
+pub fn get_commit_sha(command_succeeded: bool, sha: str) -> str {
+    if (!command_succeeded) {
+        return "git rev-parse failed";
+    }
+    return sha;
+}
+
+// ---------------------------------------------------------------------------
+// Tests: every decision above asserted against values read from the
+// original, including its own embargo and triplet tests.
+// ---------------------------------------------------------------------------
+
+test triplet_contract {
+    assert(triplet_field_count() == 6);
+    assert(triplet_field(0) == "bpb");
+    assert(triplet_field(3) == "sha");
+    assert(triplet_field(4) == "jsonl_row");
+    assert(triplet_field(5) == "gate_status");
+    assert(ledger_row_field_count() == 8);
+}
+
+test embargo_block_default_and_delegation {
+    assert(EmbargoBlock_new() == 0);
+    assert(EmbargoBlock_default() == EmbargoBlock_new());
+}
+
+test embargo_membership_gate {
+    // The original's own test: "deadbeef" blocked, "goodcommit" not.
+    assert(EmbargoBlock_is_embargoed(1, 0));
+    assert(!EmbargoBlock_is_embargoed(1, 1));
+    assert(!EmbargoBlock_is_embargoed(0, 0));
+}
+
+test emission_order_and_gates {
+    assert(emit_row_order() == "embargo,serialize,append,validate");
+    assert(emit_row(true, false, false) == "embargo blocked");
+    assert(emit_row(false, true, false) == "invalid triplet");
+    assert(emit_row(false, false, true) == "invalid triplet");
+    assert(emit_row(false, false, false) == "ok");
+    assert(triplet_is_invalid(true, false));
+    assert(triplet_is_invalid(false, true));
+    assert(!triplet_is_invalid(false, false));
+}
+
+test error_catalogue_and_append_contract {
+    assert(emit_error_count() == 4);
+    assert(emit_error_kind(0) == "embargo blocked");
+    assert(emit_error_kind(1) == "serialize error");
+    assert(emit_error_kind(2) == "write error");
+    assert(emit_error_kind(3) == "invalid triplet");
+    assert(ledger_opens_append_only());
+}
+
+test git_sha_command_shape {
+    assert(get_commit_sha_command() == "git rev-parse HEAD");
+    assert(get_commit_sha(true, "abc1234") == "abc1234");
+    assert(get_commit_sha(false, "") == "git rev-parse failed");
+}