volt: Q90 -- tree_root.py gets a root boundary, a seed check, and an import guard six spellings wide

marker + .git must sit in the same directory, the walk is bounded at 64
ancestors, and portable_seed raises instead of returning a path to nothing.
Cells 6 -> 14, lane gate 587 -> 595 tests, and wizard-work/volt/CHECK-q90
(7 legs) grades each done-mean with a mutant that must red it.

docs/queue-index.md

@@ -4,7 +4,7 @@
 
 **What this is.** One row per item of `WORK-QUEUE.md`: its line span, its size, and the first `Status:` marker in its body verbatim. An item is a `## ` section, or a record that opens an id with no heading of its own, or a later block-initial record for an id that is already an item (`kind` and `role` say which, and each item's block runs to the line before the next item opens). Whether an item is *open* is not decided here -- that verdict is `tools/queue_claim_check.py`'s, and this document does not overrule it.
 
-**What it exposes.** The queue is two-tier. 97 sections carry 86 ids because 11 ids own a second, continuation section; 42 further ids are opened by a record and own no heading at all, and they have rows and extents here -- 109 record blocks in all, 67 of them a later closure or correction for an id already opened. The same **42 ids** are listed again in the table below, which carries what a bounds row cannot -- the form that opened each one and how often the file names it: grepping `^## Q41` finds nothing while Q41 is a live item the file names 30 times.
+**What it exposes.** The queue is two-tier. 97 sections carry 86 ids because 11 ids own a second, continuation section; 42 further ids are opened by a record and own no heading at all, and they have rows and extents here -- 110 record blocks in all, 68 of them a later closure or correction for an id already opened. The same **42 ids** are listed again in the table below, which carries what a bounds row cannot -- the form that opened each one and how often the file names it: grepping `^## Q41` finds nothing while Q41 is a live item the file names 30 times.
 
 | # | id | kind | lines | bytes | role | title | first `Status:` |
 |---|---|---|---|---|---|---|---|
@@ -213,7 +213,8 @@
 | 203 | Q130 | record | 13675-13676 | 5143 | record: BOLD-LEAD | **Q130 — OPENED and REPAIRED in the same tick (volt, 2026-10-30, at the commit this record lands in; spark lane by authorship, unclaimed and taken). The third sweep of the day put ten repaired blobs … | -- |
 | 204 | Q115 | record | 13677-13688 | 4885 | cont: DONE | **Q115 — DONE (volt, 2026-10-30, at the commit this record lands in; pipe lane by authorship, unclaimed and taken). The monitor's folder-read failure dropped the folder's whole listing and printed no … | -- |
 | 205 | Q131 | record | 13689-13700 | 3836 | record: BOLD-LEAD | **Q131 — OPENED and REPAIRED in the same tick (volt, 2026-10-30; the pipe's monitor harness by authorship, unclaimed and taken). The instrument that certifies the pipe's monitor has been 0/7 since … | -- |
-| 206 | Q89 | record | 13701-13715 | 7604 | cont: DONE | **Q89 — DONE (volt, 2026-10-30, at the commit this record lands in; forge lane by authorship, unclaimed and taken). The import-time-I/O detector in the three refactor harnesses was one name list … | -- |
+| 206 | Q89 | record | 13701-13716 | 7605 | cont: DONE | **Q89 — DONE (volt, 2026-10-30, at the commit this record lands in; forge lane by authorship, unclaimed and taken). The import-time-I/O detector in the three refactor harnesses was one name list … | -- |
+| 207 | Q90 | record | 13717-13729 | 5660 | cont: DONE | **Q90 — DONE (volt, 2026-10-30, at the commit this record lands in; beam lane by authorship, unclaimed and taken). `beam/tree_root.py` had no root boundary, a `portable_seed` that returned a path to … | -- |
 
 ## Ids with no `## ` heading
 
@@ -259,7 +260,7 @@ Opened as records inside another section. `line` is the record's own opening lin
 | Q124 | 13350 | 13350 | 4 | Q95 | BULLET+BOLD | BOLD-LEAD |
 | Q126 | 13545 | 13545 | 8 | Q113 | BULLET+BOLD | BOLD-LEAD |
 | Q127 | 13577 | 13577 | 4 | Q110 | BULLET+BOLD | BOLD-LEAD |
-| Q128 | 13635 | 13635 | 1 | Q116 | BULLET+BOLD | BOLD-LEAD |
+| Q128 | 13635 | 13635 | 2 | Q116 | BULLET+BOLD | BOLD-LEAD |
 | Q129 | 13653 | 13653 | 3 | Q128 | BULLET+BOLD | BOLD-LEAD |
 | Q130 | 13675 | 13675 | 1 | Q129 | BULLET+BOLD | BOLD-LEAD |
 | Q131 | 13689 | 13685 | 2 | Q115 | BULLET+BOLD | BOLD-LEAD |
@@ -1679,17 +1680,30 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "title": "**Q131 \u2014 OPENED and REPAIRED in the same tick (volt, 2026-10-30; the pipe's monitor harness by authorship, unclaimed and taken). The instrument that certifies the pipe's monitor has been 0/7 since \u2026"
   },
   {
-   "bytes": 7604,
-   "end_line": 13715,
+   "bytes": 7605,
+   "end_line": 13716,
    "id": "Q89",
    "kind": "record",
    "line": 13701,
-   "lines": 15,
+   "lines": 16,
    "role": "continuation",
    "role_detail": "DONE",
    "status": null,
    "status_line": null,
    "title": "**Q89 \u2014 DONE (volt, 2026-10-30, at the commit this record lands in; forge lane by authorship, unclaimed and taken). The import-time-I/O detector in the three refactor harnesses was one name list \u2026"
+  },
+  {
+   "bytes": 5660,
+   "end_line": 13729,
+   "id": "Q90",
+   "kind": "record",
+   "line": 13717,
+   "lines": 13,
+   "role": "continuation",
+   "role_detail": "DONE",
+   "status": null,
+   "status_line": null,
+   "title": "**Q90 \u2014 DONE (volt, 2026-10-30, at the commit this record lands in; beam lane by authorship, unclaimed and taken). `beam/tree_root.py` had no root boundary, a `portable_seed` that returned a path to \u2026"
   }
  ],
  "ids_multi_section": {
@@ -4493,17 +4507,30 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "title": "**Q131 \u2014 OPENED and REPAIRED in the same tick (volt, 2026-10-30; the pipe's monitor harness by authorship, unclaimed and taken). The instrument that certifies the pipe's monitor has been 0/7 since \u2026"
   },
   {
-   "bytes": 7604,
-   "end_line": 13715,
+   "bytes": 7605,
+   "end_line": 13716,
    "id": "Q89",
    "kind": "record",
    "line": 13701,
-   "lines": 15,
+   "lines": 16,
    "role": "continuation",
    "role_detail": "DONE",
    "status": null,
    "status_line": null,
    "title": "**Q89 \u2014 DONE (volt, 2026-10-30, at the commit this record lands in; forge lane by authorship, unclaimed and taken). The import-time-I/O detector in the three refactor harnesses was one name list \u2026"
+  },
+  {
+   "bytes": 5660,
+   "end_line": 13729,
+   "id": "Q90",
+   "kind": "record",
+   "line": 13717,
+   "lines": 13,
+   "role": "continuation",
+   "role_detail": "DONE",
+   "status": null,
+   "status_line": null,
+   "title": "**Q90 \u2014 DONE (volt, 2026-10-30, at the commit this record lands in; beam lane by authorship, unclaimed and taken). `beam/tree_root.py` had no root boundary, a `portable_seed` that returned a path to \u2026"
   }
  ],
  "nested": [
@@ -4854,7 +4881,7 @@ The block below is the parse this document renders, byte for byte. `--check` com
    "form": "BOLD-LEAD",
    "id": "Q128",
    "line": 13635,
-   "refs": 1,
+   "refs": 2,
    "section": "Q116",
    "shape": "BULLET+BOLD"
   },
@@ -4891,9 +4918,9 @@ The block below is the parse this document renders, byte for byte. `--check` com
   "end_line": 8,
   "line": 1
  },
- "queue_bytes": 2216258,
- "queue_lines": 13715,
- "queue_sha256": "c68b8208ec31bfab2df4abdcb19d7e2e90405155dbda8e8698b06af249ef1771",
+ "queue_bytes": 2221919,
+ "queue_lines": 13729,
+ "queue_sha256": "50d716fca1ea29df3cea5a186f0fa17d16e261928a5f002af263b3853873fe85",
  "sections": [
   {
    "bytes": 3139,