diff --git a/.trinity/seals/claw_ClawSuggest.json b/.trinity/seals/claw_ClawSuggest.json
index 3c89d178f9..c2c50a6918 100644
--- a/.trinity/seals/claw_ClawSuggest.json
+++ b/.trinity/seals/claw_ClawSuggest.json
@@ -1,5 +1,5 @@
 {
-  "built_by": "t27c-bootstrap@0.5.2+4ab200073",
+  "built_by": "t27c-bootstrap@0.5.2+9448ab4be",
   "closure": [
     {
       "spec": "specs/claw/text.t27",
@@ -7,27 +7,27 @@
     }
   ],
   "config": "gen=c,rust,verilog,zig;tests=zig",
-  "gen_hash_c": "sha256:1c6dd4d239fd700edc472b628df24597dd11f5b63a76f1050aa09bffbd251da7",
-  "gen_hash_rust": "sha256:c719fcf00bf17ed2b6ff36cc2c500ee6dd6c593afde71753f543dc68d802d8bb",
-  "gen_hash_verilog": "sha256:7590f417bd9b0f1430ef2a6db553db3d0e35466f357b78a002621d2fd7e2cb42",
-  "gen_hash_zig": "sha256:a69878738101760c4f62d0be49005006e3cd0ccee945decf7c0b6fe2aa23001e",
+  "gen_hash_c": "sha256:7f8fd10201c8fc786ce03ed298ffc150166460c2d64cc3c3fea9714a21a59b77",
+  "gen_hash_rust": "sha256:b6ffaa050395bea50bd5acc89e83fe44216afa753f4f26279be723a3d60b8a43",
+  "gen_hash_verilog": "sha256:2a8ff2bd1b0b31cb34c8fc3f9fb5f4ec27c5a3b29f288c7cc6c9fe2f98c07383",
+  "gen_hash_zig": "sha256:35ccc87874786e0b00745b0e14f0b0434fa9aaa9140de5a1dc024c67dc5d5c67",
   "module": "ClawSuggest",
   "ring": 12,
   "seal_schema": 2,
-  "sealed_at": "2026-10-18T09:41:18Z",
+  "sealed_at": "2026-10-18T21:52:54Z",
   "sealed_by": "t27c-bootstrap@0.5.2",
-  "spec_hash": "sha256:43afee144a92a59e27539c51a344ae9e03d88c14e3c5ab3d9f24cddedab6c325",
+  "spec_hash": "sha256:f63b4eb62478b8b94accec867c5e0e5ff908d340771a7fe45bdc54ba05f9ff6c",
   "spec_path": "specs/claw/suggest.t27",
   "tests": {
     "failed": 0,
     "failing": [],
     "forced": false,
-    "passed": 16,
-    "total": 16,
+    "passed": 22,
+    "total": 22,
     "vacuous": 0
   },
   "toolchain": {
-    "test_runner": "sha256:1982ae948e24d00c5d221ccec12dfce1eb01204b53e37b0f857f93b16d64629d",
+    "test_runner": "sha256:8512b80da533b79289110fca4a65f3336abd7a059ca4b72ea595d5e33ff8ad10",
     "zig": "0.16.0"
   }
 }
\ No newline at end of file
diff --git a/specs/claw/suggest.t27 b/specs/claw/suggest.t27
index 32bfc227bf..951cb7f849 100644
--- a/specs/claw/suggest.t27
+++ b/specs/claw/suggest.t27
@@ -541,3 +541,62 @@ test no_hunks_and_no_ranges_post_nothing {
     assert plan(1, hf, hs, hc, hk, 0, df, ds, dl, out) == 0;
     assert out[0] == V_OUTSIDE;
 }
+
+// Tests below were added by the mutation sweep of #10673 (tick 19); each names the mutants it kills.
+
+// path_is_t27: each of the last two bytes is checked on its own (`return false` -> `return true` on '2' and on '7').
+test each_byte_of_the_extension_is_checked {
+    var no : [3]str = ["a.t37", "a.t28", "a.t2"];
+    for i in 0..3 { assert path_is_t27(no[i], no[i].len) == false; }
+}
+
+// header_new_range edges: the digit '9' (`<= '9'` -> `< '9'`), seven-digit start and count (`> 7` -> `>= 7`).
+test header_parse_takes_nine_and_seven_digits {
+    var out : [2]u32 = [0, 0];
+    var h1 : str = "@@ -9 +19,9 @@";
+    assert header_new_range(h1, h1.len, out) == true;
+    assert out[0] == 19;
+    assert out[1] == 9;
+    var h2 : str = "@@ -1 +1234567,7654321 @@";
+    assert header_new_range(h2, h2.len, out) == true;
+    assert out[0] == 1234567;
+    assert out[1] == 7654321;
+}
+
+// header_new_range: every byte the grammar fixes is checked by its own line. Each header below is
+// wrong in exactly one place, and the parse must refuse it without writing (kills `return false` ->
+// `return true` on the '-', the empty base count, the ' ' and '+' before the head range, an
+// eight-digit head count, the ' @@' tail, and `p + 1` -> `p + 2` on the tail).
+test header_parse_refuses_each_single_byte_fault {
+    var out : [2]u32 = [7, 7];
+    var bad : [8]str = ["@@ +1 +1 @@", "@@ -1, +1 @@", "@@ -1x +1 @@", "@@ -1 -1 @@", "@@ -1 +1,12345678 @@", "@@ -1 +1 x@@", "@@ -1 +1 @x", "@@ -1 +1@@ "];
+    for i in 0..8 {
+        assert header_new_range(bad[i], bad[i].len, out) == false;
+        assert out[0] == 7;
+        assert out[1] == 7;
+    }
+}
+
+// in_one_range: a one-line diff range covers its line (`dlen >= 1` -> `> 1`).
+test a_one_line_diff_range_covers_its_line {
+    var df : [1]u32 = [1];
+    var ds : [1]u32 = [5];
+    var dl : [1]u32 = [1];
+    assert in_one_range(1, 5, 5, df, ds, dl, 1) == true;
+    assert in_one_range(1, 6, 6, df, ds, dl, 1) == false;
+}
+
+// hunk_unknown: two hunks sharing exactly one line overlap, read from the later one (`f1 <= l2` -> `<`).
+test hunks_sharing_one_line_overlap_from_both_sides {
+    var hf : [2]u32 = [1, 1];
+    var hs : [2]u32 = [10, 12];
+    var hc : [2]u32 = [3, 3];
+    var hk : [2]u8 = [K_REPLACE, K_REPLACE];
+    assert hunk_unknown(0, 2, hf, hs, hc, hk) == true;
+    assert hunk_unknown(1, 2, hf, hs, hc, hk) == true;
+}
+
+// should_post: one comment is a review (`>= 1` -> `> 1`).
+test one_comment_is_a_review {
+    assert should_post(1) == true;
+}