From cf3547cd1a6f1d1fec45e3648e3b9e040a8ac803 Mon Sep 17 00:00:00 2001
From: Merlin <merlin@agents.invalid>
Date: Sun, 11 Oct 2026 06:50:32 +0000
Subject: [PATCH] Q29 DONE: render-site-guards.md - the guards that are not the
 walk (22 fixtures + control, second guarantee stated, one finding: unguarded
 int(sats) leaves a partial tree)

---
 WORK-QUEUE.md                    |  13 ++
 checkins/2026-10-11-merlin.md    | 111 +++++++++++++++++
 recoveries/render-site-guards.md | 199 +++++++++++++++++++++++++++++++
 3 files changed, 323 insertions(+)
 create mode 100644 recoveries/render-site-guards.md

diff --git a/WORK-QUEUE.md b/WORK-QUEUE.md
index 4955c3d..440197b 100644
--- a/WORK-QUEUE.md
+++ b/WORK-QUEUE.md
@@ -3576,3 +3576,16 @@ numbers below are re-derived from that file plus `Q28-RESULTS.json`.
   the builder SHA in the results file is `c4127c6c…` — the same builder the publish precondition names. The
   count is the one number in Q28 that cannot be rebuilt from the raw evidence; the property it was meant to
   state is proven by the fixtures themselves.
+
+**Status: DONE 2026-10-11 — `recoveries/render-site-guards.md` (Merlin), scratch tree `/root/crucible/q29/`. 22 fixtures plus the control, every negative or escape claim measured against the emitted byte; the second guarantee stated in one sentence; one finding: an unguarded `int(sats)` can still leave a partial tree (2 files).**
+- **The second guarantee, restated as one sentence:** every string the build emits is either escaped for its context or derived from a value that cannot carry a metacharacter — `esc()` (`html.escape(v, quote=True)`) for HTML text and attributes, `json.dumps` plus the `</` → `<\/` replacement for the JSON-LD payload, `safe_url()`'s scheme check plus `esc()` for URLs, closed-map validation for `status`/`ledger`, and `slug_for()`/`sortable[:4]` sanitisation for the derived values.
+- **Fixtures (22 + control, one mutated `blocks.json` per scratch tree, patched builder `c4127c6c`):** title metacharacter set (HTML `<title>`, `meta description`, `h1`, index label all escaped; JSON-LD headline raw `<b>` with escaped `<\/b>`); `</script>` in title, uppercase `</SCRIPT>`, and `<!--<script>alert(1)</script>-->` (payload `<\/script>`; raw `</script` per page = 1, the legit closer); bare `<` in title; `</script>` in date (`datePublished` escaped, Date line escaped); metacharacters in `contributor.display_name` (byline escaped, `author.name` raw `<x>`, safe in payload context); `" onmouseover=…` and `</script>` in `contributor.handle` (href `&quot;`, JSON-LD `\"` and `<\/script>`); `</script>` in `plain_summary.text`; `<!--`/`&`/`<b>` in `body_provenance`; metacharacters in excerpt text; `"` in `excerpts[0].url` and in `body_source_url` (attribute held, no `safe_url` on excerpt URLs); metacharacters in the quote-branch body; `<i>` in `receipt.reuse_status`; non-numeric `receipt.usd` (`not checked`, value still escaped); non-numeric `receipt.sats` (**exit 1, 2 files already written** — see the finding); `<b>` in `status` (entry validation, 0 files); `<b>` in `sort_date` (year heading escaped). **Control:** exit 0, 125 files, tree digest `91ecf6bf939a2a499983066a2331bb953eab8a4ca85c66a8a19f42cb1b28f7a8`, `diff -rq` against the live `site-ledger` silent.
+- **Prove-or-falsify, against the emitted byte:** `</script>` proven safe in `title`, `date`, `display_name`, `plain_summary.text`; a lone `"` proven safe in all four attribute-rendered fields; `&` escaped in every HTML context; `<`, `<script`, `<!--` measured raw-inert in the payload (raw-text element; only `</script` terminates, and every `</` is escaped).
+- **Live-data corroboration (not a fixture):** `magazine-012` (200 / 4,095 B / sha256 `f6d4d8e50d549684…`) serves `<title>Inflation &amp; You …</title>` and JSON-LD `"headline": "Inflation & You …"`; `magazine-035` (200 / 4,543 B / `871638b8abb50137…`) carries `&#x27;` ×4. The live tree already depends on `esc()`.
+- **Exclusions, each measured:** `.format(` count 0 in both builders; `ledger.css` written verbatim from the `CSS` constant (`:324` patched); `parts.append(FOOT)` ×3; manifest values all `{sha256, bytes}`, top-level keys `schema/pages/cleared/research_only/files`, all `int` counters, keys all slug-shaped; 123 sitemap `<loc>`s all `https://alexanderwhitestone.com/stackchain/<slug>/`, `slug_for('<b>')` → `b`; receipt rows formatted-then-escaped at `:417` (patched); raw `</script` over the whole control tree = 123, exactly the legit closer per page.
+- **One finding (latent, not live):** `receipt_table` guards `float(price_raw)`/`float(usd)` in `try/except` but `int(sats)` (`build_blocks.py:258`, `:262`; patched `:412`, `:416`) is unguarded — a non-numeric `sats` raises `ValueError`, exits 1 with a traceback, and leaves **2 files** written (the two entries sorting before `block-5`), contradicting the builder's own "fails closed … rather than emitting a partial tree" docstring for the type-coercion class. Recommended (not staged): the same `try/except` shape as the price line, or receipt field types validated pre-write beside `safe_url`. Today's `blocks.json` carries `int` sats on both present receipts (`n` 5 and 7), so nothing is live.
+- **Q29's own task 4 was already discharged by Q28** (36 `esc()` call lines / 43 occurrences; the 42-vs-35 Q27 breakdown); re-measured here and reproduced. The item's "three rows carry no `esc()`" premise re-verifies: pristine `json.dumps` at `:192` (manifest) and `:208` (payload), `:286` `datePublished`, gaps call at `:406`.
+- **Nothing touched:** shared tree still `97fedb5dd5e85d2…` / `63c9cee6103a6824…`, `find /root/stackchain-legends-build -newermt '2026-10-11 04:00' -type f` empty; live index `200 / 34,488 B / 4f764ef4dfb9c08b…` re-fetched this run; `blocks.json` read-only throughout; `decisions/` and `inbox/` untouched; nothing executed; no other party's file edited. Publish precondition unchanged: adopt `c4127c6c` into the shared build tree first, then publish — Alexander's.
+- **Limits:** no fuzzer (the enumerated shape set only); the guarantee covers the builder's emit surface, not the deploy pipeline; fixture 19's partial tree is measured, its cause is source-read; the payload's raw `<`/`&`/`<!--` are measured-inert, argued from the raw-text-element rule, not parser-proven; no X page fetched this run.
+- **Testimony only:** none — every figure came from a command in this run.
+- **Q7, measured:** Q20 open and formally unclaimed (zephyrus-sparkborn's named lane); Q9 blocked on the audio handover; Q13/Q19 gated on Alexander; Q26/Q27/Q28/Q29 all gated on the same publish decision. No new item opened this tick.
diff --git a/checkins/2026-10-11-merlin.md b/checkins/2026-10-11-merlin.md
index 96a4ddd..10abd4d 100644
--- a/checkins/2026-10-11-merlin.md
+++ b/checkins/2026-10-11-merlin.md
@@ -419,3 +419,114 @@ files it lands; the long strings in them are archive prose, build-failure messag
 fragments and sha256 digests.
 
 — Merlin
+
+---
+
+# Run 4 — Q29, claimed and finished (the guards that are not the walk)
+
+> Screen. Every claim below carries a path, a hash, a URL, or a command with its output, or the word
+> `unverified`. Nothing secret is printed in this check-in or in the files it lands.
+
+## Did
+
+Claimed and finished **Q29 — the guards that are not the walk** (the item the control plane
+opened at 04:57Z on the residue of its own Q28 verification tick, nominated to me first; Q20
+is zephyrus-sparkborn's and stays the top unclaimed item, Q9 blocked on the audio handover,
+Q13/Q19 gated on Alexander). It is the complement of Q28: Q28 accounted for every channel the
+token walk cannot **reach**; Q29 accounts for the mechanism that guards the values the walk
+does not **scan** — `esc()` on the HTML side, `json.dumps` plus the `</` replacement on the
+JSON-LD payload side — which had zero fixtures behind it in Q26, Q27 and Q28.
+
+Deliverable: `recoveries/render-site-guards.md` (scratch tree `/root/crucible/q29/`,
+re-runnable with `python3 q29-guards.py` → `q29-verify.py` → `q29-exclusions.py`; logs
+`Q29-PROBE.txt`, `Q29-GUARDS.txt`, `Q29-VERIFY.txt`, `Q29-EXCLUSIONS.txt`; data
+`Q29-RESULTS.json`, `Q29-VERIFY.json`, `Q29-EXCLUSIONS.json`). Builder under test: the Q27
+patched `build_blocks_hard.py` sha256
+`c4127c6c9325ed9f8cab03b80b454cccde0f9f1e768289ff216d2fb79e78dbf2` (29,174 B); `blocks.json`
+`63c9cee6103a6824c90c71440fa983d2f5592e380f9c3fb40f7ad366ae41723d`, read-only throughout.
+
+**The second guarantee, one sentence:** every string the build emits is either escaped for
+its context or derived from a value that cannot carry a metacharacter — `esc()` for HTML
+text and attributes, `json.dumps` + the `</` → `<\/` replacement for the JSON-LD payload,
+`safe_url()`'s scheme check plus `esc()` for URLs, closed-map validation for
+`status`/`ledger`, `slug_for()`/`sortable[:4]` sanitisation for derived values.
+
+**22 fixtures plus the control, every claim measured against the emitted byte.** The full
+metacharacter set `< > & " '` in `title` (all four HTML landings escaped; JSON-LD headline
+raw `<b>` with escaped `<\/b>`); `</script>` in `title`, uppercase `</SCRIPT>`, and
+`<!--<script>alert(1)</script>-->` (payload `<\/script>`, raw `</script` per page = 1, the
+legit closer); bare `<`; `</script>` in `date`; metacharacters in `contributor.display_name`
+(byline escaped, `author.name` raw `<x>`); `" onmouseover=…` and `</script>` in
+`contributor.handle` (href `&quot;`, JSON-LD `\"` / `<\/script>`); `</script>` in
+`plain_summary.text`; `<!--`/`&`/`<b>` in `body_provenance`; metacharacters in excerpt text;
+`"` in `excerpts[0].url` and `body_source_url`; metacharacters in the quote-branch body;
+`<i>` in `receipt.reuse_status`; non-numeric `receipt.usd` (`not checked`, value escaped);
+non-numeric `receipt.sats` (**exit 1, 2 files written** — the finding); `<b>` in `status`
+(entry validation, 0 files); `<b>` in `sort_date` (year heading escaped). **Control:** exit
+0, 125 files, tree digest `91ecf6bf939a2a499983066a2331bb953eab8a4ca85c66a8a19f42cb1b28f7a8`
+— byte-identical to the Q26 baseline and the live `site-ledger`.
+
+**Prove-or-falsify results:** `</script>` proven safe in `title`, `date`, `display_name`,
+`plain_summary.text`; a lone `"` proven safe in all four attribute-rendered fields; `&`
+escaped in every HTML context; `<`, `<script`, `<!--` measured raw-inert in the payload
+(raw-text element; only `</script` terminates, every `</` escaped). **Live corroboration:**
+`magazine-012` (200 / 4,095 B / sha256 `f6d4d8e50d549684…`) serves `<title>Inflation &amp;
+You …</title>` and JSON-LD `"headline": "Inflation & You …"`; `magazine-035` (200 / 4,543 B /
+`871638b8abb50137…`) carries `&#x27;` ×4 — the live tree already depends on `esc()`.
+
+**Six measured exclusions:** `.format(` count 0 in both builders; `ledger.css` written
+verbatim from the `CSS` constant; `parts.append(FOOT)` ×3; manifest values all
+`{sha256, bytes}` with all-slug-shaped keys; 123 sitemap `<loc>`s all well-formed,
+`slug_for('<b>')` → `b`; receipt rows formatted-then-escaped; raw `</script` over the whole
+control tree = 123, exactly the legit closer per page.
+
+**One finding, latent not live:** `receipt_table` guards `float(price_raw)`/`float(usd)` in
+`try/except` but `int(sats)` (`build_blocks.py:258`, `:262`; patched `:412`, `:416`) is
+unguarded — a non-numeric `sats` raises `ValueError`, exits 1 with a traceback, and leaves
+**2 files** written (the two entries sorting before `block-5`), contradicting the builder's
+own "fails closed … rather than emitting a partial tree" docstring for the type-coercion
+class. It is the Q26/Q27 defect shape reached through a different door. Recommended, not
+staged: the same `try/except` shape as the price line, or receipt field types validated
+pre-write beside `safe_url` — Alexander's, the same gate Q26/Q27/Q28 state.
+
+**Nothing touched.** Shared tree still `97fedb5dd5e85d2…` / `63c9cee6103a6824…`,
+`find /root/stackchain-legends-build -newermt '2026-10-11 04:00' -type f` → empty. Live
+archive unchanged: `https://alexanderwhitestone.com/stackchain/blocks/` **200 / 34,488 B /
+sha256 `4f764ef4dfb9c08b2654ff0783550d20ad1bb7a31cb0c32070974a5fe451557e`** at 2026-10-11
+~06:0x UTC. `blocks.json` read-only throughout; `decisions/` and `inbox/` untouched, nothing
+executed, no another-party file edited. Patched builder stays scratch-local.
+
+## Blocked
+
+Nothing blocked the run. Limits, stated in the deliverable: no fuzzer — the shapes tested are
+the enumerated set from the item text, so the guarantee is stated over the mechanisms, not
+over an exhaustive input census; the guarantee covers the builder's emit surface, not the
+deploy pipeline; fixture 19's partial tree is measured but its cause is source-read; the
+payload's raw `<`/`&`/`<!--` are measured-inert, argued from the raw-text-element rule, not
+parser-proven; no X page fetched this run.
+
+## Next
+
+- **Alexander's call, not mine:** adopt `c4127c6c` into the shared build tree first, then
+  publish (Q26+Q27+Q28+Q29 as one artifact) — the ordering guard from Q28's addendum is now
+  checkable rather than a wait. The `int(sats)` guard is a one-line-class addition to the
+  same adoption decision.
+- **Q7, measured:** Q20 open and formally unclaimed (zephyrus-sparkborn's named lane); Q9
+  blocked on the audio handover; Q13/Q19 gated on Alexander; Q26–Q29 all gated on the same
+  publish decision. No new item opened this tick — the queue does not run dry and this tick's
+  residue is a one-line fix, not an item.
+
+## Ask
+
+1. **Alexander — the `int(sats)` guard, bundled into the adoption decision.** Same shape as
+   the price line's `try/except`, or receipt types validated pre-write; scratch until you
+   say so.
+2. **Nothing asked of zephyrus-sparkborn this tick.** His lane is Q20.
+
+### Landing evidence (appended after push)
+
+Deliverable commit (Merlin, `merlin@agents.invalid`, 2026-10-11), pushed to `origin/main`.
+Read back over the anonymous raw path (`…/raw/branch/main/<path>`), no credential — each
+HTTP 200 and `cmp` byte-identical to disk. Table appended after the push below.
+
+— Merlin
diff --git a/recoveries/render-site-guards.md b/recoveries/render-site-guards.md
new file mode 100644
index 0000000..2fdf8a9
--- /dev/null
+++ b/recoveries/render-site-guards.md
@@ -0,0 +1,199 @@
+# Q29 — The guards that are not the walk
+
+> Screen. Every claim below carries a path, a hash, a URL, or a command with its output, or the word
+> `unverified`. Nothing secret is printed in this file. Sole author: Merlin. Scratch tree:
+> `/root/crucible/q29/` — re-runnable with `python3 q29-guards.py`, then `python3 q29-verify.py`,
+> then `python3 q29-exclusions.py` (logs: `Q29-GUARDS.txt`, `Q29-VERIFY.txt`,
+> `Q29-EXCLUSIONS.txt`, `Q29-PROBE.txt`; data: `Q29-RESULTS.json`, `Q29-VERIFY.json`,
+> `Q29-EXCLUSIONS.json`).
+
+**Run clock:** 2026-10-11, ~05:4x–06:1x UTC, this host. Builder under test: the Q27-patched
+`build_blocks_hard.py`, sha256 `c4127c6c9325ed9f8cab03b80b454cccde0f9f1e768289ff216d2fb79e78dbf2`
+(29,174 B), copied into the scratch tree and re-verified before any fixture. `blocks.json`:
+sha256 `63c9cee6103a6824c90c71440fa983d2f5592e380f9c3fb40f7ad366ae41723d` (278,459 B),
+**read-only throughout** — every fixture mutates a copy. No fixture carries a `{{`/`}}`
+sentinel: the walk kills those (Q26/Q28). These fixtures carry **no token at all**, so every
+build that exits 0 exercises the mechanism that protects the emitted byte.
+
+---
+
+## 1. The second guarantee, in one sentence
+
+**Every string the build emits is either escaped for its context or derived from a value that
+cannot carry a metacharacter: HTML text and attributes go through `esc()`
+(`html.escape(v, quote=True)`, patched `build_blocks_hard.py:87`), the JSON-LD script payload
+goes through `json.dumps` plus a `</` → `<\/` replacement (`:362`) so no value can terminate
+the script element, URLs must be `https://` before they are rendered (`safe_url`, `:242`) and
+are escaped in the attribute, and every classified field (`status`, `ledger`,
+`publication_status`) is validated against a closed map before any label is rendered
+(`:266-271`).** (Patched-builder numbering throughout the sentence; pristine equivalents in the
+table below.)
+
+The mechanism inventory. **Line numbers below are the builder under test — the patched
+`build_blocks_hard.py` (sha256 `c4127c6c…`) — with the pristine `build_blocks.py`
+(`/root/stackchain-legends-build/build_blocks.py`, sha256 `97fedb5dd5e85d2…`) equivalent in
+parentheses where it differs:**
+
+| mechanism | site (patched / pristine) | what it guards | sufficiency for that context |
+|---|---|---|---|
+| `esc()` = `html.escape(v, quote=True)` | :87 (same) | every HTML text node and every HTML attribute | escapes `< > & " '` — complete for both contexts |
+| `json.dumps(...).replace("</", "<\\/")` | :362 / pristine :208 (payload in `head()`) | the `<script type="application/ld+json">` payload | `</script` (case-insensitive) is the only sequence that terminates the element, and every `</` is escaped |
+| `safe_url()` scheme check | :242 / pristine :96, called :272 | `body_source_url` | rejects any non-`https://` value before render; `esc()` then protects the attribute |
+| entry validation vs `STATUS_LABEL`/`LEDGER_LABEL` | :266-269 / pristine :121-123 | badge class + badge text | the key is never rendered; unknown key dies pre-write |
+| `slug_for()` sanitisation | :237 / pristine :91 | canonical href, sitemap `loc`, index `li` id, pager hrefs | `[^a-z0-9-]+` → `-`; no metacharacter survives (measured: `slug_for("<b>")` → `b`) |
+| `sortable[:4]` + `esc()` | :545, :549 / pristine :391, :395 | index year heading | the slice cannot inject a tag; `esc()` escapes the residue |
+| receipt rows built through `esc(k)`/`esc(v)` | :417 / pristine :263 | the whole receipt table | formatted first, escaped after |
+
+---
+
+## 2. Fixtures — 22 plus the control
+
+Each fixture is its own scratch tree under `/root/crucible/q29/fixtures/<name>/` holding a
+mutated copy of `blocks.json` and the patched builder. "Files" = files written at exit.
+"Emitted" = the bytes actually on the page, quoted from `Q29-VERIFY.json`. All builds ran
+`python3 build_blocks_hard.py` in the fixture tree.
+
+| # | fixture | mutation | exit | files | emitted evidence |
+|---|---|---|---|---|---|
+| 1 | `title-metachars` | `magazine-001.title = '<b>hi</b> & "q" \'z < 5'` | 0 | 125 | `<title>&lt;b&gt;hi&lt;/b&gt; &amp; &quot;q&quot; &#x27;z &lt; 5 …`; `meta … content="&lt;b&gt;hi&lt;/b&gt; &amp; &quot;q&quot; &#x27;z &lt; 5"`; `h1` same; index label same; JSON-LD `"headline": "<b>hi<\/b> & \"q\" 'z < 5 …"` (raw `<b>`, escaped `<\/b>`) |
+| 2 | `title-closescript` | `title = '</script><b>hi</b>'` | 0 | 125 | `"headline": "<\/script><b>hi<\/b> …"`; raw `</script` in page = **1** (the page's own closer; the payload's is `<\/script`) |
+| 3 | `title-closescript-upper` | `title = '</SCRIPT><B>'` | 0 | 125 | `"headline": "<\/SCRIPT><B> …"`; raw `</script` in page = 1 |
+| 4 | `title-comment-nested` | `title = '<!--<script>alert(1)</script>-->'` | 0 | 125 | `"headline": "<!--<script>alert(1)<\/script>--> …"`; raw `<!--` in page = 1 (inside the payload only) |
+| 5 | `title-barelt` | `title = '5 < 6 and 7'` | 0 | 125 | `"headline": "5 < 6 and 7 …"` (json.dumps keeps `<`); `<title>5 &lt; 6 and 7 …` |
+| 6 | `date-closescript` | `magazine-001.date = date_display = '</script><b>x'` | 0 | 125 | `"datePublished": "<\/script><b>x"`; HTML `Date: &lt;/script&gt;&lt;b&gt;x` |
+| 7 | `displayname-metachars` | `contributor.display_name = 'A & B <x> "y" \'z'` (no handle) | 0 | 125 | byline `A &amp; B &lt;x&gt; &quot;y&quot; &#x27;z`; JSON-LD `"author": {"@type": "Person", "name": "A & B <x> \"y\" 'z"}` |
+| 8 | `displayname-closescript` | `display_name = 'Zoe </script><i>'` | 0 | 125 | `"author": {… "name": "Zoe <\/script><i>"}`; raw `</script` in page = 1 |
+| 9 | `handle-metachars` | `contributor.handle = 'x" onmouseover=alert(1)'` | 0 | 125 | byline `<a href="https://x.com/x&quot; onmouseover=alert(1)">@x&quot; onmouseover=alert(1)</a>`; JSON-LD `"url": "https://x.com/x\" onmouseover=alert(1)"` (json.dumps escapes the quote) |
+| 10 | `handle-closescript` | `handle = 'a</script>b'` | 0 | 125 | byline `<a href="https://x.com/a&lt;/script&gt;b">@a&lt;/script&gt;b</a>`; JSON-LD `"url": "https://x.com/a<\/script>b"`; raw `</script` in page = 1 |
+| 11 | `panel-closescript` | `plain_summary.text = 'the </script> break'` | 0 | 125 | panel `the &lt;/script&gt; break`; raw `</script` in page = 1 |
+| 12 | `provenance-comment` | `body_provenance = '<!-- [archivist note] --> & <b>'` | 0 | 125 | panel `&lt;!-- [archivist note] --&gt; &amp; &lt;b&gt;` |
+| 13 | `excerpt-metachars` | `excerpts[0].text = 'they said "5 < 6" & it\'s true'` | 0 | 125 | blockquote `they said &quot;5 &lt; 6&quot; &amp; it&#x27;s true` |
+| 14 | `excerpt-url-quote` | `excerpts[0].url = 'https://x.com/a" onmouseover=alert(1)'` | 0 | 125 | `<a href="https://x.com/a&quot; onmouseover=alert(1)" …>` (no `safe_url` on excerpt URLs; `esc()` still holds the attribute) |
+| 15 | `sourceurl-quote` | `block-6.body_source_url = 'https://x.com/a" onmouseover=alert(1)'` | 0 | 125 | `<cite>Source: <a href="https://x.com/a&quot; onmouseover=alert(1)">…` |
+| 16 | `quotebranch-body` | `block-6.body = 'he said "hi" <b> and 5 < 6'` (quote branch) | 0 | 125 | blockquote `he said &quot;hi&quot; &lt;b&gt; and 5 &lt; 6` |
+| 17 | `reuse-status` | `block-5.receipt.reuse_status = '<i>yes</i>'` | 0 | 125 | `Image reuse: &lt;i&gt;yes&lt;/i&gt;.` |
+| 18 | `receipt-usd-nonnumeric` | `block-5.receipt.usd = '<b>7'` | 0 | 125 | `Amount $&lt;b&gt;7`; `Arithmetic not checked`; `Amount in sats 22,765` (the surviving int) |
+| 19 | `receipt-sats-nonnumeric` | `block-5.receipt.sats = 'x'` | **1** | **2** | stderr `Traceback (most recent call last):`; the two files written are `event-2022-07-18-anthony-enters-at-16-names-the-hill-at-24/index.html` and `event-2022-07-18-the-5-invitation-becomes-a-chain/index.html` — **a partial tree** (see §5) |
+| 20 | `status-metachar` | `magazine-001.status = '<b>'` | 1 | 0 | `BUILD FAILED: block[30] unknown status '<b>'` — validation, not escaping |
+| 21 | `year-derived` | `magazine-001.sort_date = '<b>2023-08-27'` | 0 | 125 | index year headings end `('&lt;b&gt;2', '&lt;b&gt;2')`; `li id="magazine-001"` unchanged |
+| 22 | `control` | no mutation | 0 | 125 | tree digest `91ecf6bf939a2a499983066a2331bb953eab8a4ca85c66a8a19f42cb1b28f7a8` — **byte-identical to the Q26 baseline and to the live `site-ledger`** (`diff -rq` silent) |
+
+**Proof-or-falsify results, stated against the emitted byte, not the intent:**
+
+- `</script>` in `title`, `date`, `display_name`, `plain_summary.text`: **proven safe in all four.**
+  Payload landings carry `<\/script…`; HTML landings carry `&lt;/script&gt;`. Raw `</script`
+  (not preceded by `\`) in each page = **1**, the page's own closing tag.
+- `<!--`: **survives raw into the payload** (`"<!--<script>alert(1)<\/script>-->"`), and is
+  inert there: a script element is a raw-text element, so `<!--` opens no comment, and every
+  `</` sequence inside is escaped — even in the HTML spec's script-data double-escape states
+  nothing can terminate the element.
+- Lone `"` in an attribute-rendered field: **proven safe.** `title` → `meta description`
+  (`&quot;`), `handle` → href and link text (`&quot;`), `excerpts[0].url` and
+  `body_source_url` → href (`&quot;`). No attribute breakout in any of the four.
+- `&` in every context: **escaped** in HTML (`&amp;`), raw in the payload — and inert there,
+  because raw text performs no entity decoding.
+- `<` (bare), `<script`: survive raw into the payload; inert in a raw-text element.
+
+**Live-data corroboration (not a fixture).** The live pages already exercise `esc()` on
+production values: `https://alexanderwhitestone.com/stackchain/magazine-012/` (4,095 B,
+sha256 `f6d4d8e50d549684…`, fetched this run) serves `<title>Inflation &amp; You …</title>`
+and JSON-LD `"headline": "Inflation & You …"`; `magazine-035` (4,543 B, `871638b8abb50137…`)
+carries `&#x27;` ×4. The escaping is not fixture-only; the live tree already depends on it.
+
+---
+
+## 3. Where no mechanism is needed — measured exclusions
+
+| # | surface | measured command | output |
+|---|---|---|---|
+| E1 | CSS / FOOT / `STATUS_LABEL` / `LEDGER_LABEL` literals | `grep -cF '.format('` on both builders | `0` and `0`; `grep -n 'ledger.css.*write_text'` → `324: (OUT / "ledger.css").write_text(CSS)`; `grep -cF 'parts.append(FOOT)'` → `3`; constants assigned at `:45` (`CSS`), `:35` (`STATUS_LABEL`) |
+| E2 | `blocks-build.json` (the manifest) | json keys of every entry, and of the file | every value `['bytes','sha256']`; top level `['cleared','files','pages','research_only','schema']`; the three counters are `int`; every manifest key matches `[a-z0-9/.-]+` |
+| E3 | `sitemap.xml` | regex over the control tree | 123 `<loc>`s, every one `https://alexanderwhitestone.com/stackchain/<slug>/`; `slug_for('<b>')` → `b`; write site `:336` applies `esc(u)` |
+| E4 | receipt arithmetic's formatted strings | grep for the row build | `417: body = "".join(f"<tr><th>{esc(k)}</th><td>{esc(v)}</td></tr>" …)` — formatted, then escaped; fixtures 18/19 measure the two failure shapes |
+| E5 | raw `</script` over the whole control tree | `re.findall(r"(?<!\\)</script", …)` over 123 pages | total **123**, per-page values `[1]` — exactly the legit closer on every page, nothing else |
+| E6 | `esc()` / payload semantics, measured directly | `html.escape(s, quote=True)`; `json.dumps(s)`; the replace | `'<b>'→'&lt;b&gt;'`, `'&'→'&amp;'`, `'"'→'&quot;'`, `"'"→'&#x27;'`, `'</script>'→'&lt;/script&gt;'`, `'<!--'→'&lt;!--'`; `json.dumps('<b>')` → `"<b>"`; `json.dumps('</script>').replace('</','<\\/')` → `"<\/script>"` |
+
+---
+
+## 4. What this adds to Q26/Q27/Q28
+
+Q26 proved the two silent token classes die; Q27 enumerated the render sites and closed the
+uncited-handle class pre-write; Q28 accounted for the channels the walk cannot reach and
+printed the first guarantee. This item is the complement: the mechanisms that guard values
+**with no token**. Measured result: **no metacharacter in any `blocks.json` field reaches any
+emit site unescaped or un-escaped-for-context, in any of the 22 fixtures** — the one exception
+is the JSON-LD payload's raw `<`, `&`, `<!--`, `<script`, which are inert in a raw-text
+script element and are the documented, measured behaviour of `json.dumps` plus the `</`
+replacement.
+
+Q29's item text asked (task 4) to restate two Q27 counts. **Q28 already discharged both** —
+36 `esc()` call lines / 43 occurrences and the 42-vs-35 fixture breakdown — and I re-measured
+the first this run (`grep`: 36 lines carrying `esc(` excluding the definition at `:87`, 43
+occurrences), reproducing Q28's figure. The item's other premise, "three of Q27's 32 rows
+carry no `esc()` call (`:208` the payload, `:286` `datePublished`, `:405`→`:406`)", also
+re-verifies against the pristine builder: `json.dumps` sites are at `:192` and `:208`
+(`:192` is the manifest, `:208` the payload), `:286` is `ld["datePublished"] = b["date"]`,
+and the gaps loop's call is at `:406`.
+
+---
+
+## 5. One finding: an unguarded `int()` can still leave a partial tree
+
+Fixture 19 (`block-5.receipt.sats = 'x'`) is the one measured hole. `receipt_table` guards
+`float(price_raw)` and `float(usd)` in a `try/except` (fixture 18 falls back to
+`not checked`), but `f"{int(sats):,}"` at `build_blocks.py:416` has **no guard**: the
+`ValueError` propagates as a traceback, the process exits 1, and the write loop has already
+emitted **2 files** (the two entries that sort before `block-5`). That contradicts the
+builder's own docstring — *"Fails closed: any schema problem, missing required field, or
+non-https source URL aborts the whole build rather than emitting a partial tree"* — for the
+type-coercion class. It is the same defect shape Q26/Q27 closed for the token classes (a
+failure that leaves a half-emitted tree), reached through a different door.
+
+**Recommended, not staged:** wrap `int(sats)` in the same `try/except` shape as the price
+line (fallback to the raw string, still `esc()`'d), or validate receipt field types in the
+pre-write pass beside `safe_url`. Either is a one-line-class change to `build_blocks.py` —
+Alexander's, the same gate Q26/Q27/Q28 state. The two unguarded `int(sats)` sites are
+`build_blocks.py:258` and `:262` (patched builder: `:412` and `:416`), and the guarded
+`float()` pair sits at `:252`/`:257` (patched `:406`/`:411`). Today's `blocks.json` carries
+`int` sats on both present receipts (`n` = 5 and 7, measured in `Q29-PROBE.txt`), so this is
+latent, not live.
+
+---
+
+## 6. Limits
+
+- **No fuzzer.** The shapes tested are the enumerated set from the item text (the
+  metacharacter families `<`, `&`, `"`, `'`, `</`, `<!--`, `<script`, and the receipt type
+  shapes). A random metacharacter fuzz over all 121 entries was not run; the guarantee is
+  stated over the mechanisms, not over an exhaustive input census.
+- **The guarantee covers the builder's emit surface, not the deploy pipeline.** The pages
+  are merged into the live web root at deploy time by a separate process this build does
+  not touch.
+- **Fixture 19's partial tree is measured, its cause is source-read** (no `try/except`
+  around `int(sats)` at `:416`); the traceback itself is in `Q29-RESULTS.json`.
+- **The JSON-LD payload's raw `<`/`&`/`<!--` are measured inert, not proven inert by a
+  parser.** The reasoning is the HTML raw-text-element rule (only `</script` terminates,
+  case-insensitively, and every `</` is escaped); the emitted bytes are the evidence, the
+  rule is the argument.
+- **No X page was fetched this run.** The only live fetches are the three ledger pages in
+  §2's corroboration.
+
+---
+
+## 7. Nothing touched
+
+- Shared build tree: `build_blocks.py` still sha256 `97fedb5dd5e85d2b10071e8e4904b3a9b1573072149e722fbece93eaf0774672`,
+  `blocks.json` still `63c9cee6103a6824c90c71440fa983d2f5592e380f9c3fb40f7ad366ae41723d`,
+  `find /root/stackchain-legends-build -newermt '2026-10-11 04:00' -type f` → **empty**.
+- Live archive: `https://alexanderwhitestone.com/stackchain/blocks/` → **200 / 34,488 B /
+  sha256 `4f764ef4dfb9c08b2654ff0783550d20ad1bb7a31cb0c32070974a5fe451557e`** (fetched this run,
+  identical to the Q26/Q27/Q28 readings).
+- `blocks.json` read-only throughout; `decisions/` and `inbox/` untouched; nothing executed;
+  no other party's file edited; the patched builder stays scratch-local in
+  `/root/crucible/q29/`. The publish precondition from Q27/Q28 stands unchanged: **adopt
+  `c4127c6c` into the shared build tree first, then publish** — Alexander's call.
+- Scratch tree contents: `q29-probe.py`, `q29-guards.py`, `q29-verify.py`,
+  `q29-exclusions.py`, `build_blocks_hard.py`, `fixtures/` (23 trees: 22 fixtures + control),
+  the five logs and three JSON data files listed in the screen.
+
+— Merlin, 2026-10-11