docs(k3): round 14, the declared-structure route at the shipped defaults

The report, with every measurement carrying its denominator and both
instrument forms side by side on every row -- including the proof that the two
forms cannot both reach 2 761, because 2 739 of 2 761 fasit titles carry a
numbering token and the two keys then demand mutually exclusive strings.

Also states two things round 13 left unsaid:

- XML that is not STS gives 0 plans and exit 2, and the `.txt` known-positive
  shows it is general `okf build` behaviour for any structureless document,
  not an `.xml` defect. Separating the two states would change the outcome on
  0 of the 4 reference corpora, so the gate stays.
- Which two instruments were corrected in scratch and what the correction is.
  With the shipped matcher the XML bundle scores 0/6 with `rang: null` on
  every question, including the known-positive whose top excerpt IS the fasit.

Round 13's 14 two-file directories are re-classified on measurement: they were
false positives of the text route reading the document's own contents listing,
not the publisher reusing a title, and they are gone. Two remain, the same two
the PDF arm has.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -9,6 +9,41 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **A section the SOURCE DECLARES now takes the route declared structure takes,
+  at the shipped defaults.** `.xml` gained a reader in the entry above and the
+  reader reached its ceiling -- **2 761 of 2 761** heading lines -- while the
+  build delivered **23 concepts and 15 of 2 761 boundaries**. Everything after
+  the reader ate it, and both steps are measured: the **orphan check** removed
+  **710 of 2 761** (710 of 710 removed headings are followed immediately by
+  another heading and **0 of 2 051** delivered ones are -- they are container
+  sections), and **Arm F** folded **2 066** more, 2 089 -> 23.
+  - `extract.xml_outline` reports the marks the reader wrote itself. There is
+    **no bridge** and therefore no tolerance constant and no `unresolved`
+    bucket: the reader appended the line it names. That is the difference from
+    `pdf_outline`, whose naive nearest-line rule was wrong on 1 840 of 2 762.
+  - `propose.RULE_XML_SECTION` (`rule:xml-section`) is its own name in
+    `RULE_NAMES` and in `_ORPHAN_EXEMPT`, so an artifact still distinguishes an
+    element the reader transcribed from a bridged bookmark
+    (`rule:pdf-outline`) and from a heading somebody guessed (`rule:heading`).
+  - The route is chosen by the ROW (`DECLARED_STRUCTURE_IDS = {"xml"}`), never
+    by the text: the same markdown arriving from a `.md` file is still a guess.
+    **No other file type changes one byte** -- `diff -r` on the five-document
+    reference folder is empty (52 md, 26 concepts, 0 of 5 rejected, 0 `.xml`
+    files in it), `okf project` is still byte-equal to `okf build`, the pinned
+    K2 bundle is unchanged, and the PDF arm still proposes 2 762 segments.
+  - Measured at SHIPPED DEFAULTS, not behind a flag: **2 761 concepts**;
+    **2 761 of 2 761** declared sections became a concept with the source's own
+    directory and title; **0** concepts match no declaration; `a)`-points
+    **0 of 4 954**; table blocks **10 of 10**; hit@1/8/50 **3/6 · 5/6 · 6/6**
+    (from 0/6 · 0/6 · 0/6) with the known-positive at rank 1. Cross-arm,
+    **2 761 shared concept ids** -- 100 % of the XML bundle and 2 761 of 2 762
+    of the PDF arm's, up from round 13's 2 022.
+  - Two directories of 2 738 still hold two concepts (`11`, `12`): the
+    publisher reuses a section number for two distinct sections, and it is the
+    same 2 the PDF arm has. Round 13's 14 such directories were false positives
+    of the text route reading the document's own contents listing, and they are
+    gone.
+
 - **`.xml` is a core file type, NISO-STS aware, with a generic fallback.** A
   publisher's own viewer delivers a zip that holds 0 html, 1 xml and 109
   images; `okf build` on it was **110 of 110 unreadable, 0 plans, exit 2**, and
@@ -38,6 +73,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `.xml` never routes through the converter, and it is measured about 12x
     faster and about 30x smaller in peak memory than the PDF arm on the same
     document and the same machine.
+  - **XML that is not STS gives 0 plans and a FAILED build, and that is not an
+    `.xml` defect.** The known-positive that decides it: a folder holding one
+    `.txt` of prose with no headings gives exactly the same three lines and the
+    same exit 2. This is general `okf build` behaviour for any structureless
+    document -- extraction works, 0 unreadable, the text is there, and the
+    proposer has nothing to propose. The gate that refuses a run with no plans
+    stays: a run replaying zero plans would emit a flat bundle and report it as
+    a success. Separating "0 plans, 0 unreadable" from "0 plans because nothing
+    could be read" would change the outcome on **0 of the 4** reference
+    corpora, so it is not separated.
   - Report: `docs/2026-09-11-k3-runde13-xml-sts.md`.
 
 ### Fixed