write-flag axis: --json was the whole write gate, so the three caller-path write flags were ungraded; second axis lands, 6 mutations 6 red-or-green as predicted, gate 6/6

Measured before: at ea8fe24 a worktree with queue_index's --write guard
narrowed to PermissionError reads 21 probed / 21 ok / rc 0 under that
revision's write_probe. Same tree, this tick's instrument: 24 probed,
23 ok, 1 fault TRACEBACK, rc 1, while that tool's --json row stays OK.

Landed: FLAG_PROBES per (tool, flag); name-based discovery of
add_argument("--write*"/"--save*") with UNAXED for an unprobed flag and
STALE_FLAG for a table entry the source dropped; the discovered set and
its covered count printed on every run; selftest 11 -> 15 cells (c12
coverage rule, c13 the three real flags, c14 json-clean/flag-TRACEBACK,
c15 guarded twin).

Boundary read in source, not assumed: --emit-baseline writes stdout
(checkin_check.py:935, only file write inside c33), check_lint --log is a
read.

Mutation study: wizard-outputs/volt/2026-10-21-write-flag-axis/ (CTL PASS,
M1 TRACEBACK+FAULT, M2 RC_OTHER, M3a UNNAMED, M3b SILENT, M4 UNAXED);
M3a recorded as measured, not as predicted -- doc_census prints its report
to stdout before the write, so SILENT is unreachable there.

verify.py: 6 legs, 6 pass, 0 fault. write_probe --repo .: 24 probed,
24 ok. doc_command_check 64/64. doc_census 0 STALE. TOOLS.md re-rendered,
byte-identical.

docs/queue-index.md

@@ -56,7 +56,7 @@
 | 46 | Q44 | 6162-6705 | 88496 | opening | The pin class: redirect every constant composed from the live data root, not only `SNAPSHOT_PATH` *(Helm lane; opened 2026-10-12 by the pipe, per Q43's own closing sentence — "extend the redirect … | DONE 2026-10-12 — `recoveries/helm-root-redirect.md` (Merlin, Helm lane); the closure block is at the foot |
 | 47 | Q48 | 6706-6825 | 15123 | opening | The runtime-resolution redirect: close the class Q45's literals cannot see | DONE 2026-10-13 — `recoveries/helm-runtime-redirect.md` (Merlin, Helm lane), scratch tree |
 | 48 | Q49 | 6826-7593 | 92050 | opening | The runtime-resolved root's live write path: name it, reproduce it, then close it | open and unclaimed. Opened by the pipe 2026-10-13 |
-| 49 | Q45 | 7594-10502 | 514132 | opening | §9 follow-on — the home-directory channel *(Helm lane; Merlin)* | OPEN — awaiting Alexander's zoom/whole-shop answer; build is the pipe's. |
+| 49 | Q45 | 7594-10520 | 520054 | opening | §9 follow-on — the home-directory channel *(Helm lane; Merlin)* | OPEN — awaiting Alexander's zoom/whole-shop answer; build is the pipe's. |
 
 ## Ids with no `## ` heading
 
@@ -71,9 +71,9 @@ Opened as records inside another section. `line` is the record's own opening lin
 | Q50 | 6990 | 6990 | 46 | Q49 | BULLET+BOLD | BOLD-LEAD |
 | Q51 | 7106 | 7106 | 37 | Q49 | BULLET+BOLD | BOLD-LEAD |
 | Q52 | 7167 | 7167 | 90 | Q49 | BULLET+BOLD | BOLD-LEAD |
-| Q53 | 7292 | 7246 | 148 | Q49 | BULLET+BOLD | BOLD-LEAD |
+| Q53 | 7292 | 7246 | 149 | Q49 | BULLET+BOLD | BOLD-LEAD |
 | Q63 | 9918 | 9909 | 17 | Q45 | BULLET+BOLD | BOLD-LEAD |
-| Q64 | 10308 | 10308 | 11 | Q45 | BULLET+BOLD | BOLD-LEAD |
+| Q64 | 10308 | 10308 | 12 | Q45 | BULLET+BOLD | BOLD-LEAD |
 
 **Not in this document.** Ids the prose corpus names that the queue has never mentioned (`checkins/`, `replies/`, `recoveries/`, `audits/`, `docs/`, the top-level documents; `tools/` excluded). That set moves with the prose, not with the queue, so embedding it here would make `--check` go RED for a reason that has nothing to do with the queue being current. It is reported on demand: `python3 tools/queue_index.py --outside`.
 
@@ -218,7 +218,7 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "form": "BOLD-LEAD",
    "id": "Q53",
    "line": 7292,
-   "refs": 148,
+   "refs": 149,
    "section": "Q49",
    "shape": "BULLET+BOLD"
   },
@@ -236,7 +236,7 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "form": "BOLD-LEAD",
    "id": "Q64",
    "line": 10308,
-   "refs": 11,
+   "refs": 12,
    "section": "Q45",
    "shape": "BULLET+BOLD"
   }
@@ -246,9 +246,9 @@ The block below is the parse this document renders, byte for byte. `--check` com
   "end_line": 8,
   "line": 1
  },
- "queue_bytes": 1406393,
- "queue_lines": 10502,
- "queue_sha256": "88948ef446c4171e126a023538f78c1a0df49ea074fe8fca6726f6167f1167c9",
+ "queue_bytes": 1412315,
+ "queue_lines": 10520,
+ "queue_sha256": "3d9324d77b80ed1feb1ca575d018a1f7c1d3dce9084dc8116d64adcb5e869329",
  "sections": [
   {
    "bytes": 3139,
@@ -827,11 +827,11 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "title": "The runtime-resolved root's live write path: name it, reproduce it, then close it"
   },
   {
-   "bytes": 514132,
-   "end_line": 10502,
+   "bytes": 520054,
+   "end_line": 10520,
    "id": "Q45",
    "line": 7594,
-   "lines": 2909,
+   "lines": 2927,
    "role": "opening",
    "role_detail": "",
    "status": "OPEN \u2014 awaiting Alexander's zoom/whole-shop answer; build is the pipe's.",