feat(ms-ai-architect): Spor 3 Port 3 (rapporterende gulv) — KB-tillit-signal i SessionStart [skip-docs]

Det rapporterende gulvet (§4 Port 3, P3b): SessionStart-hooken surfacer en
KB-tillit-énlinjer fra cachet verified-staleness-report.json. Et GULV, ikke en
gate (§4c — unngå alarm-tretthet på 84 %-signal).

summarizeTrustFreshness (detection-schedule.mjs, ren, speiler
summarizeSkillQuality): surfacer KUN drift (stale-since-verified) +
kontraktbrudd (unverified) — det handlingsbare «bekreft mot kilde»-settet.
unmigrated (Spor-1-backlog, 306 i dag) ekskluderes bevisst: ved det volumet
ville det fyre hver økt og bli støy; migrerings-censusen hører i CT5 (P3c).
Tolererer manglende/malformed cache → null (gitignored, fraværende i fersk
klon, krasjer aldri hooken).

session-start-context.mjs: leser cachen read-only (samme mønster som
skill-quality-blokken), dytter linjen når den finnes.

Ende-til-ende verifisert: injisert stale-rapport → «KB-tillit: 3 filer driftet
siden verifisering, 1 uverifisert — bekreft mot kilde (aldri auto-fiks)»; ekte
korpus (306 unmigrated) → taus (ingen falsk alarm).

TDD (Iron Law): 8 nye tester. Suite 612/612. Plugin-validering PASS.

tests/kb-update/test-detection-schedule.test.mjs

@@ -27,6 +27,7 @@ import {
   summarizeSkillLifecycle,
   summarizeCourses,
   summarizeSkillQuality,
+  summarizeTrustFreshness,
   daysSinceLastPoll,
 } from '../../scripts/kb-update/lib/detection-schedule.mjs';
 import { writeScheduleConfig } from '../../scripts/kb-update/write-schedule-config.mjs';
@@ -623,3 +624,67 @@ test('run-detection.mjs source — spawns node, NEVER claude (the ToS boundary m
   assert.doesNotMatch(code, /['"`]claude['"`]/i, 'no claude binary referenced in code');
   assert.doesNotMatch(code, /anthropic/i, 'code must not call Anthropic');
 });
+
+// ===========================================================================
+// summarizeTrustFreshness — KB-trust reporting floor at session start (Spor 3 P3b)
+// ===========================================================================
+// Reads the CACHED verified-staleness-report.json (produced by
+// report-verified-staleness.mjs on the KB-refresh cadence) — it NEVER judges
+// live. That cache is gitignored => ABSENT in a fresh clone, so this MUST
+// tolerate a missing/malformed report → null and never crash the hook. Mirrors
+// summarizeSkillQuality: a pure one-liner, null when there is nothing worth
+// surfacing. A REPORTING FLOOR, not a gate (§4c — avoid alarm fatigue): it
+// surfaces only drift (stale-since-verified) + contract breaches (unverified).
+// `unmigrated` (the Spor-1 backlog, 306 today) is DELIBERATELY excluded — at
+// that volume it would fire every session and become pure noise; the migration
+// census belongs to CT5 (P3c), not this per-session line.
+
+const STALE_REPORT = {
+  generated_at: '2026-06-29',
+  counts: { total: 10, fresh: 4, stale: 3, unverified: 1, unmigrated: 2, outOfScope: 0 },
+  flagged: [],
+};
+
+test('summarizeTrustFreshness — surfaces drift + contract breaches', () => {
+  const s = summarizeTrustFreshness(STALE_REPORT);
+  assert.match(s, /KB-tillit:/);
+  assert.match(s, /3 .*driftet/, 'stale count surfaced');
+  assert.match(s, /1 uverifisert/, 'unverified count surfaced');
+});
+
+test('summarizeTrustFreshness — stale only renders without the unverified clause', () => {
+  const s = summarizeTrustFreshness({ counts: { stale: 2, unverified: 0, unmigrated: 50 } });
+  assert.match(s, /2 filer driftet/);
+  assert.doesNotMatch(s, /uverifisert/);
+});
+
+test('summarizeTrustFreshness — unverified only renders without the drift clause', () => {
+  const s = summarizeTrustFreshness({ counts: { stale: 0, unverified: 1, unmigrated: 50 } });
+  assert.match(s, /1 uverifisert/);
+  assert.doesNotMatch(s, /driftet/);
+});
+
+test('summarizeTrustFreshness — singular "fil" for exactly one drifted file', () => {
+  const s = summarizeTrustFreshness({ counts: { stale: 1, unverified: 0 } });
+  assert.match(s, /1 fil driftet/);
+  assert.doesNotMatch(s, /1 filer/, 'no plural for a single file');
+});
+
+test('summarizeTrustFreshness — unmigrated-only is silent (Spor-1 backlog, not a drift signal)', () => {
+  assert.equal(summarizeTrustFreshness({ counts: { stale: 0, unverified: 0, unmigrated: 306 } }), null);
+});
+
+test('summarizeTrustFreshness — clean corpus (no stale, no unverified) returns null', () => {
+  assert.equal(summarizeTrustFreshness({ counts: { total: 5, fresh: 5, stale: 0, unverified: 0 } }), null);
+});
+
+test('summarizeTrustFreshness — missing report (fresh clone, gitignored) returns null', () => {
+  assert.equal(summarizeTrustFreshness(null), null);
+  assert.equal(summarizeTrustFreshness(undefined), null);
+});
+
+test('summarizeTrustFreshness — malformed report returns null (never crashes the hook)', () => {
+  assert.equal(summarizeTrustFreshness({}), null, 'no counts => unusable');
+  assert.equal(summarizeTrustFreshness('nonsense'), null, 'non-object');
+  assert.equal(summarizeTrustFreshness({ counts: 'bad' }), null, 'counts not an object');
+});