feat(ms-ai-architect): C2.2 valgfritt fritekst-felt free-context.md i onboarding (TDD) [skip-docs]

Spor C / C2.2 (#3, akseptanse K3): fanger et fritt prosa-felt i onboarding og
overflater det (kappet) ambient i hver sesjon.

- lib/user-data.mjs: FREE_CONTEXT_FILE (utenfor ORG_FILES — valgfri, teller ikke
  mot fullføring), collapseProse() surfacer fri kontekst som ÉTT felt uansett
  markdown-struktur (ingen stille drop), capValue() ekstrahert (DRY).
- session-start-context.mjs: leser free-context.md valgfritt (ingen count++).
- onboarding-agent.md: ny Phase 6 (valgfri); onboard.md: prosess/Task/status.
- 11 agenter: uniform 6. bullet (grep 11/11).
- Tester FØR kode: user-data 25/25 (+9), test-hooks 11/11 (+1 K3-ambient).

Gates: validate 239/0/0 · kb-update 200 · kb-eval 100 · kb-integrity 192/192
(220 baseline-warns) · discovery 13/13 · gitleaks 3 pre-eksisterende.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/kb-update/lib/user-data.mjs

@@ -32,6 +32,14 @@ export const ORG_FILES = Object.freeze([
   'business-references.md',
 ]);
 
+// The optional free-prose file (C2.2, #3): "everything else you want the plugin
+// to know". Deliberately NOT in ORG_FILES — its presence is optional and must
+// NOT affect the onboarding-completeness count (the SessionStart hook gates that
+// on `count < ORG_FILES.length`). It is read for the ambient summary only.
+export const FREE_CONTEXT_FILE = 'free-context.md';
+
+const FREE_CONTEXT_LABEL = 'Fri kontekst';
+
 const DEFAULT_SUMMARY_CAP = 25; // max summary lines (hook-injection budget)
 const DEFAULT_MAX_VALUE_LEN = 160; // per-field char cap (free-text guard)
 
@@ -89,6 +97,30 @@ function extractSections(content) {
   return out;
 }
 
+/**
+ * Collapse a markdown document to one prose line: drop frontmatter and every
+ * header line, then squeeze whitespace. Used for the free-context file, which is
+ * ONE free field (not structured H2 sections) and may be plain prose — so it is
+ * surfaced whole rather than per-section, never silently dropped. Pure.
+ * @param {string} content
+ * @returns {string}
+ */
+function collapseProse(content) {
+  return stripFrontmatter(content)
+    .split('\n')
+    .filter((line) => !/^#{1,6}\s/.test(line))
+    .join(' ')
+    .replace(/\s+/g, ' ')
+    .trim();
+}
+
+/** Truncate a field value to maxValueLen, appending an ellipsis when cut. Pure. */
+function capValue(value, maxValueLen) {
+  return value.length > maxValueLen
+    ? `${value.slice(0, maxValueLen - 1).trimEnd()}…`
+    : value;
+}
+
 /**
  * Build a compact, deterministic org-context summary from org file contents.
  * PURE — takes a `{ filename: contentString }` map (the caller reads the files)
@@ -113,12 +145,19 @@ export function buildOrgSummary(orgFiles, opts = {}) {
     const content = orgFiles[name];
     if (typeof content !== 'string' || !content.trim()) continue;
     for (const [header, value] of extractSections(content)) {
-      const trimmed =
-        value.length > maxValueLen ? `${value.slice(0, maxValueLen - 1).trimEnd()}…` : value;
-      fields.push(`${header}: ${trimmed}`);
+      fields.push(`${header}: ${capValue(value, maxValueLen)}`);
     }
   }
 
+  // Free-prose context (C2.2, #3): the optional sixth file, surfaced LAST as one
+  // "Fri kontekst" field regardless of internal markdown structure, so a plain
+  // paragraph is never silently dropped (acceptance K3). Capped like any field.
+  const freeContent = orgFiles[FREE_CONTEXT_FILE];
+  if (typeof freeContent === 'string' && freeContent.trim()) {
+    const body = collapseProse(freeContent);
+    if (body) fields.push(`${FREE_CONTEXT_LABEL}: ${capValue(body, maxValueLen)}`);
+  }
+
   if (fields.length === 0) return '';
   if (fields.length <= cap) return fields.join('\n');