diff --git a/gen/rust/t27os/release.rs b/gen/rust/t27os/release.rs
new file mode 100644
index 0000000000..bb45155e81
--- /dev/null
+++ b/gen/rust/t27os/release.rs
@@ -0,0 +1,636 @@
+// Generated from .t27 spec
+// DO NOT EDIT — generated by t27c
+// NOT LOWERED BY THIS BACKEND: 21 test(s), 0 invariant(s), 0 function(s) with no body.
+// This backend emits declarations only. The spec's checks live in
+// the Zig and Verilog outputs; do not read this file as verified.
+
+pub const VERSION_MAJOR: u32 = 0;
+
+pub const VERSION_MINOR: u32 = 1;
+
+pub const VERSION_PATCH: u32 = 0;
+
+pub const NO_VERSION: u64 = 18446744073709551615;
+
+pub const PART_MAX: u32 = 999999;
+
+pub fn pack_version(major: u32, minor: u32, patch: u32) -> u64 {
+    return ((((major as u64) << 40) | ((minor as u64) << 20)) | (patch as u64));
+}
+
+pub fn current_version() -> u64 {
+    return pack_version(VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH);
+}
+
+pub fn version_major(v: u64) -> u32 {
+    return (((v >> 40) & 1048575) as u32);
+}
+
+pub fn version_minor(v: u64) -> u32 {
+    return (((v >> 20) & 1048575) as u32);
+}
+
+pub fn version_patch(v: u64) -> u32 {
+    return ((v & 1048575) as u32);
+}
+
+pub fn put_number(out: &mut [u8], cap: usize, w: usize, v: u32) -> usize {
+    let mut scale: u32 = 1;
+    while ((v / scale) >= 10) {
+        scale = (scale * 10);
+    }
+    let mut k: usize = w;
+    let mut rest: u32 = v;
+    while (scale > 0) {
+        let d: u32 = (rest / scale);
+        if (k < cap) {
+            out[(k) as usize] = ((48 + d) as u8);
+        }
+        k += 1;
+        rest = (rest - (d * scale));
+        scale = (scale / 10);
+    }
+    return k;
+}
+
+pub fn put_semver(out: &mut [u8], cap: usize, w: usize, v: u64) -> usize {
+    let mut k: usize = put_number(out, cap, w, version_major(v));
+    k = put_str(out, cap, k, ".", 1);
+    k = put_number(out, cap, k, version_minor(v));
+    k = put_str(out, cap, k, ".", 1);
+    return put_number(out, cap, k, version_patch(v));
+}
+
+pub fn read_part(t: &[u8], n: usize, at: usize) -> u64 {
+    if (at >= n) {
+        return NO_VERSION;
+    }
+    let mut i: usize = at;
+    let mut v: u32 = 0;
+    while (((i < n) && (t[(i) as usize] >= b'0')) && (t[(i) as usize] <= b'9')) {
+        if ((i - at) >= 6) {
+            return NO_VERSION;
+        }
+        v = ((v * 10) + ((t[(i) as usize] - b'0') as u32));
+        i += 1;
+    }
+    if (i == at) {
+        return NO_VERSION;
+    }
+    if ((t[(at) as usize] == b'0') && ((i - at) > 1)) {
+        return NO_VERSION;
+    }
+    return (((v as u64) << 32) | (i as u64));
+}
+
+pub fn semver_parse(t: &[u8], n: usize) -> u64 {
+    let mut a: u64 = read_part(t, n, 0);
+    if (a == NO_VERSION) {
+        return NO_VERSION;
+    }
+    let mut p: usize = ((a & 4294967295) as usize);
+    if ((p >= n) || (t[(p) as usize] != b'.')) {
+        return NO_VERSION;
+    }
+    let mut b: u64 = read_part(t, n, (p + 1));
+    if (b == NO_VERSION) {
+        return NO_VERSION;
+    }
+    p = ((b & 4294967295) as usize);
+    if ((p >= n) || (t[(p) as usize] != b'.')) {
+        return NO_VERSION;
+    }
+    let mut c: u64 = read_part(t, n, (p + 1));
+    if (c == NO_VERSION) {
+        return NO_VERSION;
+    }
+    p = ((c & 4294967295) as usize);
+    if (p != n) {
+        return NO_VERSION;
+    }
+    return pack_version(((a >> 32) as u32), ((b >> 32) as u32), ((c >> 32) as u32));
+}
+
+pub fn is_newer(candidate: u64, current: u64) -> bool {
+    if ((candidate == NO_VERSION) || (current == NO_VERSION)) {
+        return false;
+    }
+    return (candidate > current);
+}
+
+pub const MANIFEST_URL: &'static str = "https://github.com/gHashTag/t27/releases/latest/download/t27os-release.t27";
+
+pub const URL_PREFIX: &'static str = "https://github.com/gHashTag/t27/releases/";
+
+pub const URL_PREFIX_LEN: usize = 41;
+
+pub const KEY_VERSION: &'static str = "pub const VERSION : str = ";
+
+pub const KEY_BUILD: &'static str = "pub const BUILD : u32 = ";
+
+pub const KEY_SHA: &'static str = "pub const SHA256 : str = ";
+
+pub const KEY_MIN: &'static str = "pub const MIN_MACOS : str = ";
+
+pub const KEY_URL: &'static str = "pub const URL : str = ";
+
+pub const KEY_NOTES: &'static str = "pub const NOTES : str = ";
+
+pub const M_OK: u8 = 0;
+
+pub const M_NO_VERSION: u8 = 1;
+
+pub const M_NO_BUILD: u8 = 2;
+
+pub const M_BAD_SHA: u8 = 3;
+
+pub const M_BAD_MIN: u8 = 4;
+
+pub const M_BAD_URL: u8 = 5;
+
+pub const M_BAD_NOTES: u8 = 6;
+
+pub const NO_FIELD: u64 = 18446744073709551615;
+
+pub fn at_line_start(t: &[u8], i: usize) -> bool {
+    if (i == 0) {
+        return true;
+    }
+    return (t[((i - 1)) as usize] == 10);
+}
+
+pub fn starts_here(t: &[u8], n: usize, at: usize, key: &'static str, key_len: usize) -> bool {
+    if ((at + key_len) > n) {
+        return false;
+    }
+    let mut j: usize = 0;
+    while (j < key_len) {
+        if (t[((at + j)) as usize] != key.as_bytes()[(j) as usize]) {
+            return false;
+        }
+        j += 1;
+    }
+    return true;
+}
+
+pub fn field_str(t: &[u8], n: usize, key: &'static str, key_len: usize) -> u64 {
+    let mut i: usize = 0;
+    while (i < n) {
+        if (at_line_start(t, i) && starts_here(t, n, i, key, key_len)) {
+            let q: usize = (i + key_len);
+            if ((q >= n) || (t[(q) as usize] != 34)) {
+                return NO_FIELD;
+            }
+            let mut e: usize = (q + 1);
+            while (((e < n) && (t[(e) as usize] != 34)) && (t[(e) as usize] != 10)) {
+                e += 1;
+            }
+            if ((e >= n) || (t[(e) as usize] != 34)) {
+                return NO_FIELD;
+            }
+            return ((((q + 1) as u64) << 32) | (((e - q) - 1) as u64));
+        }
+        i += 1;
+    }
+    return NO_FIELD;
+}
+
+pub fn field_num(t: &[u8], n: usize, key: &'static str, key_len: usize) -> u64 {
+    let mut i: usize = 0;
+    while (i < n) {
+        if (at_line_start(t, i) && starts_here(t, n, i, key, key_len)) {
+            let mut e: usize = (i + key_len);
+            let mut v: u64 = 0;
+            while (((e < n) && (t[(e) as usize] >= b'0')) && (t[(e) as usize] <= b'9')) {
+                if ((e - (i + key_len)) >= 9) {
+                    return NO_FIELD;
+                }
+                v = ((v * 10) + ((t[(e) as usize] - b'0') as u64));
+                e += 1;
+            }
+            if (e == (i + key_len)) {
+                return NO_FIELD;
+            }
+            return v;
+        }
+        i += 1;
+    }
+    return NO_FIELD;
+}
+
+pub fn field_start(f: u64) -> usize {
+    return ((f >> 32) as usize);
+}
+
+pub fn field_len(f: u64) -> usize {
+    return ((f & 4294967295) as usize);
+}
+
+pub fn sha_ok(t: &[u8], n: usize) -> bool {
+    if (n != 64) {
+        return false;
+    }
+    let mut i: usize = 0;
+    while (i < n) {
+        let c: u8 = t[(i) as usize];
+        if !((((c >= b'0') && (c <= b'9')) || ((c >= b'a') && (c <= b'f')))) {
+            return false;
+        }
+        i += 1;
+    }
+    return true;
+}
+
+pub fn url_ok(t: &[u8], n: usize) -> bool {
+    if (n <= URL_PREFIX_LEN) {
+        return false;
+    }
+    if !(starts_here(t, n, 0, URL_PREFIX, URL_PREFIX_LEN)) {
+        return false;
+    }
+    let mut i: usize = 0;
+    while (i < n) {
+        if (((((t[(i) as usize] <= 32) || (t[(i) as usize] == 34)) || (t[(i) as usize] == 39)) || (t[(i) as usize] == 92)) || (t[(i) as usize] > 126)) {
+            return false;
+        }
+        i += 1;
+    }
+    return true;
+}
+
+pub fn macos_parse(t: &[u8], n: usize) -> u32 {
+    let mut a: u64 = read_part(t, n, 0);
+    if (a == NO_VERSION) {
+        return 4294967295;
+    }
+    let major: u32 = ((a >> 32) as u32);
+    let mut p: usize = ((a & 4294967295) as usize);
+    if (p == n) {
+        return (major * 1000);
+    }
+    if (t[(p) as usize] != b'.') {
+        return 4294967295;
+    }
+    let mut b: u64 = read_part(t, n, (p + 1));
+    if (b == NO_VERSION) {
+        return 4294967295;
+    }
+    p = ((b & 4294967295) as usize);
+    if (p != n) {
+        return 4294967295;
+    }
+    return ((major * 1000) + ((b >> 32) as u32));
+}
+
+pub fn macos_meets(min_text: &[u8], n: usize, host: u32) -> bool {
+    let m: u32 = macos_parse(min_text, n);
+    if (m == 4294967295) {
+        return false;
+    }
+    return (host >= m);
+}
+
+pub fn manifest_check(t: &[u8], n: usize) -> u8 {
+    let v: u64 = field_str(t, n, KEY_VERSION, 26);
+    if (v == NO_FIELD) {
+        return M_NO_VERSION;
+    }
+    if (semver_parse(&t[(field_start(v)) as usize..((field_start(v) + field_len(v))) as usize], field_len(v)) == NO_VERSION) {
+        return M_NO_VERSION;
+    }
+    if (field_num(t, n, KEY_BUILD, 24) == NO_FIELD) {
+        return M_NO_BUILD;
+    }
+    let s: u64 = field_str(t, n, KEY_SHA, 25);
+    if (s == NO_FIELD) {
+        return M_BAD_SHA;
+    }
+    if !(sha_ok(&t[(field_start(s)) as usize..((field_start(s) + field_len(s))) as usize], field_len(s))) {
+        return M_BAD_SHA;
+    }
+    let m: u64 = field_str(t, n, KEY_MIN, 28);
+    if (m == NO_FIELD) {
+        return M_BAD_MIN;
+    }
+    if (macos_parse(&t[(field_start(m)) as usize..((field_start(m) + field_len(m))) as usize], field_len(m)) == 4294967295) {
+        return M_BAD_MIN;
+    }
+    let u: u64 = field_str(t, n, KEY_URL, 22);
+    if (u == NO_FIELD) {
+        return M_BAD_URL;
+    }
+    if !(url_ok(&t[(field_start(u)) as usize..((field_start(u) + field_len(u))) as usize], field_len(u))) {
+        return M_BAD_URL;
+    }
+    let w: u64 = field_str(t, n, KEY_NOTES, 24);
+    if (w == NO_FIELD) {
+        return M_BAD_NOTES;
+    }
+    if !(url_ok(&t[(field_start(w)) as usize..((field_start(w) + field_len(w))) as usize], field_len(w))) {
+        return M_BAD_NOTES;
+    }
+    return M_OK;
+}
+
+pub fn put_line_text(out: &mut [u8], cap: usize, w: usize, s: &'static str, s_len: usize) -> usize {
+    let mut k: usize = put_str(out, cap, w, s, s_len);
+    if (k < cap) {
+        out[(k) as usize] = 10;
+    }
+    return (k + 1);
+}
+
+pub fn put_slice(out: &mut [u8], cap: usize, w: usize, b: &[u8], b_len: usize) -> usize {
+    let mut i: usize = 0;
+    while (i < b_len) {
+        if ((w + i) < cap) {
+            out[((w + i)) as usize] = b[(i) as usize];
+        }
+        i += 1;
+    }
+    return (w + b_len);
+}
+
+pub fn put_tag(out: &mut [u8], cap: usize, w: usize, v: u64) -> usize {
+    let mut k: usize = put_str(out, cap, w, "v", 1);
+    return put_semver(out, cap, k, v);
+}
+
+pub fn put_zip_name(out: &mut [u8], cap: usize, w: usize, v: u64) -> usize {
+    let mut k: usize = put_str(out, cap, w, "T27OS-", 6);
+    k = put_semver(out, cap, k, v);
+    return put_str(out, cap, k, ".zip", 4);
+}
+
+pub fn manifest_text(out: &mut [u8], cap: usize, v: u64, build: u32, sha: &[u8], sha_len: usize) -> usize {
+    let mut w: usize = 0;
+    w = put_line_text(out, cap, w, "; T27 OS release manifest, written by specs/t27os/release.t27 manifest_text. The app reads the", 94);
+    w = put_line_text(out, cap, w, "; six constants below and nothing else.", 39);
+    w = put_line_text(out, cap, w, "module T27osReleaseManifest;", 28);
+    w = put_str(out, cap, w, KEY_VERSION, 26);
+    w = put_str(out, cap, w, "\"", 1);
+    w = put_semver(out, cap, w, v);
+    w = put_line_text(out, cap, w, "\";", 2);
+    w = put_str(out, cap, w, KEY_BUILD, 24);
+    w = put_number(out, cap, w, build);
+    w = put_line_text(out, cap, w, ";", 1);
+    w = put_str(out, cap, w, KEY_SHA, 25);
+    w = put_str(out, cap, w, "\"", 1);
+    w = put_slice(out, cap, w, sha, sha_len);
+    w = put_line_text(out, cap, w, "\";", 2);
+    w = put_str(out, cap, w, KEY_MIN, 28);
+    w = put_line_text(out, cap, w, "\"11.0\";", 7);
+    w = put_str(out, cap, w, KEY_URL, 22);
+    w = put_str(out, cap, w, "\"", 1);
+    w = put_str(out, cap, w, URL_PREFIX, 41);
+    w = put_str(out, cap, w, "download/", 9);
+    w = put_tag(out, cap, w, v);
+    w = put_str(out, cap, w, "/", 1);
+    w = put_zip_name(out, cap, w, v);
+    w = put_line_text(out, cap, w, "\";", 2);
+    w = put_str(out, cap, w, KEY_NOTES, 24);
+    w = put_str(out, cap, w, "\"", 1);
+    w = put_str(out, cap, w, URL_PREFIX, 41);
+    w = put_str(out, cap, w, "tag/", 4);
+    w = put_tag(out, cap, w, v);
+    w = put_line_text(out, cap, w, "\";", 2);
+    return w;
+}
+
+pub const CHECK_EVERY_S: u64 = 21600;
+
+pub const CONFIRM_AFTER_S: u64 = 60;
+
+pub fn check_due(now: u64, last_check: u64) -> bool {
+    if (last_check == 0) {
+        return true;
+    }
+    if (now < last_check) {
+        return true;
+    }
+    return ((now - last_check) >= CHECK_EVERY_S);
+}
+
+pub fn idle_enough(busy_panes: u32) -> bool {
+    return (busy_panes == 0);
+}
+
+pub fn should_check(now: u64, last_check: u64, busy_panes: u32) -> bool {
+    return (check_due(now, last_check) && idle_enough(busy_panes));
+}
+
+pub const OFFER_NONE: u8 = 0;
+
+pub const OFFER_UPDATE: u8 = 1;
+
+pub const OFFER_BAD_MANIFEST: u8 = 2;
+
+pub const OFFER_OLD_MACOS: u8 = 3;
+
+pub const OFFER_REJECTED: u8 = 4;
+
+pub fn offer(check: u8, candidate: u64, current: u64, rejected: u64, os_ok: bool) -> u8 {
+    if (check != M_OK) {
+        return OFFER_BAD_MANIFEST;
+    }
+    if !(is_newer(candidate, current)) {
+        return OFFER_NONE;
+    }
+    if (candidate == rejected) {
+        return OFFER_REJECTED;
+    }
+    if !(os_ok) {
+        return OFFER_OLD_MACOS;
+    }
+    return OFFER_UPDATE;
+}
+
+pub fn sha_matches(computed: &[u8], computed_len: usize, wanted: &[u8], wanted_len: usize) -> bool {
+    if (!(sha_ok(computed, computed_len)) || !(sha_ok(wanted, wanted_len))) {
+        return false;
+    }
+    let mut i: usize = 0;
+    while (i < 64) {
+        if (computed[(i) as usize] != wanted[(i) as usize]) {
+            return false;
+        }
+        i += 1;
+    }
+    return true;
+}
+
+pub const U_IDLE: u8 = 0;
+
+pub const U_CHECKING: u8 = 1;
+
+pub const U_DOWNLOADING: u8 = 2;
+
+pub const U_VERIFYING: u8 = 3;
+
+pub const U_STAGED: u8 = 4;
+
+pub const U_SWAPPED: u8 = 5;
+
+pub const EV_CHECK: u8 = 0;
+
+pub const EV_OFFER: u8 = 1;
+
+pub const EV_NO_OFFER: u8 = 2;
+
+pub const EV_DOWNLOADED: u8 = 3;
+
+pub const EV_FAILED: u8 = 4;
+
+pub const EV_SHA_OK: u8 = 5;
+
+pub const EV_SHA_BAD: u8 = 6;
+
+pub const EV_SIGNED: u8 = 7;
+
+pub const EV_SWAP: u8 = 8;
+
+pub fn update_step(state: u8, event: u8, busy_panes: u32) -> u8 {
+    if (((event == EV_FAILED) || (event == EV_SHA_BAD)) || (event == EV_NO_OFFER)) {
+        return U_IDLE;
+    }
+    if ((state == U_IDLE) && (event == EV_CHECK)) {
+        if idle_enough(busy_panes) {
+            return U_CHECKING;
+        }
+        return U_IDLE;
+    }
+    if ((state == U_CHECKING) && (event == EV_OFFER)) {
+        return U_DOWNLOADING;
+    }
+    if ((state == U_DOWNLOADING) && (event == EV_DOWNLOADED)) {
+        return U_VERIFYING;
+    }
+    if ((state == U_VERIFYING) && (event == EV_SHA_OK)) {
+        return U_VERIFYING;
+    }
+    if ((state == U_VERIFYING) && (event == EV_SIGNED)) {
+        return U_STAGED;
+    }
+    if ((state == U_STAGED) && (event == EV_SWAP)) {
+        if idle_enough(busy_panes) {
+            return U_SWAPPED;
+        }
+        return U_STAGED;
+    }
+    return state;
+}
+
+pub const BOOT_RUN: u8 = 0;
+
+pub const BOOT_ROLLBACK: u8 = 1;
+
+pub const BOOT_BROKEN: u8 = 2;
+
+pub fn boot_action(pending_marker: bool, previous_kept: bool) -> u8 {
+    if !(pending_marker) {
+        return BOOT_RUN;
+    }
+    if previous_kept {
+        return BOOT_ROLLBACK;
+    }
+    return BOOT_BROKEN;
+}
+
+pub fn confirm_due(uptime_s: u64) -> bool {
+    return (uptime_s >= CONFIRM_AFTER_S);
+}
+
+pub fn previous_after(swapped: bool, rolled_back: bool, previous_kept: bool) -> bool {
+    if rolled_back {
+        return false;
+    }
+    if swapped {
+        return true;
+    }
+    return previous_kept;
+}
+
+pub fn rejected_after(boot: u8, running: u64, rejected: u64) -> u64 {
+    if (boot == BOOT_ROLLBACK) {
+        return running;
+    }
+    return rejected;
+}
+
+pub const PLAN_STEPS: u32 = 6;
+
+pub fn plan_text(out: &mut [u8], cap: usize, v: u64) -> usize {
+    let mut w: usize = 0;
+    w = put_str(out, cap, w, "# T27 OS release ", 17);
+    w = put_semver(out, cap, w, v);
+    w = put_line_text(out, cap, w, " -- the plan only; nothing below was run", 40);
+    w = put_line_text(out, cap, w, "# Publishing needs the owner's yes. T27OS_SIGN_ID names a Developer ID Application identity (else ad hoc).", 106);
+    w = put_line_text(out, cap, w, "1. build:", 9);
+    w = put_line_text(out, cap, w, "   make t27os T27OS_BUILD=$(git rev-list --count HEAD)", 54);
+    w = put_line_text(out, cap, w, "2. zip:", 7);
+    w = put_str(out, cap, w, "   ditto -c -k --keepParent target/t27os/T27OS.app target/t27os/", 64);
+    w = put_zip_name(out, cap, w, v);
+    w = put_line_text(out, cap, w, "", 0);
+    w = put_line_text(out, cap, w, "3. sha256:", 10);
+    w = put_str(out, cap, w, "   shasum -a 256 target/t27os/", 30);
+    w = put_zip_name(out, cap, w, v);
+    w = put_line_text(out, cap, w, "", 0);
+    w = put_line_text(out, cap, w, "4. manifest:", 12);
+    w = put_line_text(out, cap, w, "   tri t27os manifest --build $(git rev-list --count HEAD) --sha <the digest of step 3> > target/t27os/t27os-release.t27", 120);
+    w = put_line_text(out, cap, w, "5. notes (the commits since the last tag):", 42);
+    w = put_line_text(out, cap, w, "   git log --format='- %s' $(git describe --tags --abbrev=0 --match 'v*' 2>/dev/null || git rev-list --max-parents=0 HEAD)..HEAD > target/t27os/notes.md", 152);
+    w = put_line_text(out, cap, w, "6. publish (the owner's yes first):", 35);
+    w = put_str(out, cap, w, "   gh release create ", 21);
+    w = put_tag(out, cap, w, v);
+    w = put_str(out, cap, w, " target/t27os/", 14);
+    w = put_zip_name(out, cap, w, v);
+    w = put_str(out, cap, w, " target/t27os/t27os-release.t27 --title 'T27 OS ", 48);
+    w = put_semver(out, cap, w, v);
+    w = put_line_text(out, cap, w, "' --notes-file target/t27os/notes.md", 36);
+    return w;
+}
+
+pub fn publish_allowed(plan_only: bool, owner_yes: bool) -> bool {
+    if plan_only {
+        return false;
+    }
+    return owner_yes;
+}
+
+pub const REFUSAL: &'static str = "tri t27os release: publishing needs the owner's yes and is not done by this verb; run it with --plan and follow the steps by hand";
+
+pub const REFUSAL_LEN: usize = 129;
+
+pub fn buf_has(buf: &[u8], buf_len: usize, needle: &'static str, needle_len: usize) -> bool {
+    if (needle_len > buf_len) {
+        return false;
+    }
+    let mut start: usize = 0;
+    while ((start + needle_len) <= buf_len) {
+        let mut k: usize = 0;
+        let mut diff: usize = 0;
+        while (k < needle_len) {
+            if (buf[((start + k)) as usize] != needle.as_bytes()[(k) as usize]) {
+                diff += 1;
+            }
+            k += 1;
+        }
+        if (diff == 0) {
+            return true;
+        }
+        start += 1;
+    }
+    return false;
+}
+
+pub fn put_str(dst: &mut [u8], cap: usize, w: usize, s: &'static str, s_len: usize) -> usize {
+    let mut i: usize = 0;
+    while (i < s_len) {
+        if ((w + i) < cap) {
+            dst[((w + i)) as usize] = s.as_bytes()[(i) as usize];
+        }
+        i += 1;
+    }
+    return (w + s_len);
+}
+