feat(knowledge): model + effort routing enter the register, dated [skip-docs]

C1: two entries the optimization lens can cite for the model/effort axis,
both read out of the primary sources in this session rather than from the
plan's 2026-07-14 summary of them.

Verifying corrected the plan's own numbers: effort is settable in SIX
places, not five (/effort, the /model slider, --effort,
CLAUDE_CODE_EFFORT_LEVEL, settings effortLevel, skill/subagent
frontmatter), the default is high on every supporting model EXCEPT Opus
4.7 (xhigh), and the level count is model-dependent (Opus 4.6 and Sonnet
4.6 have no xhigh).

- BP-MODEL-001: subagent `model` defaults to `inherit`, so a subagent
  that names no model costs what the session costs; the documented pin
  is overridable by CLAUDE_CODE_SUBAGENT_MODEL and per-invocation model
- BP-MODEL-002: effort is an axis separate from model choice, and higher
  is not universally better (`max` "may show diminishing returns and is
  prone to overthinking")
- both carry the 2026-07-07 model/effort blog as a corroborating source
  with a real `published` date, so B1's evidence-age rule has teeth:
  measured stale with reasons ['evidence-age'] at a reference date 378
  days past publication while their verified stamps are pristine. The
  docs pages themselves get NO published date — they carry none, and
  guessing one in the field whose whole job is dating evidence is the
  lie the rule exists to catch
- new blanket guard: every corroborating source must carry a parseable
  published date. Without it newestEvidenceMs() returns null and the
  entry stays green on evidence of any age — a silent hole. Seen red
  against its own defect before it was trusted
- knowledge-refresh-cli's stale branch no longer expires on every new
  entry: its reference date has to sit after every `verified` stamp, was
  bumped once for BP-SUB-001 and would have needed a third bump now, so
  it moves to a date no stamp can reach

Register 14 -> 16 entries. Frozen v5.0.0 snapshots untouched (no scanner
output changes); suite 1579/0.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NKjojcdYYiCQP5AudUyQ5e

tests/lib/best-practices-register.test.mjs

@@ -73,6 +73,40 @@ describe('bundled register integrity (Verifiseringsplikt)', () => {
       assert.match(e.source.verified, /^\d{4}-\d{2}-\d{2}$/, `${e.id} bad verified date`);
     }
   });
+
+  // A corroborating source without a published date is a SILENT hole: newestEvidenceMs()
+  // returns null for the entry and the evidence-age rule cannot judge evidence it cannot
+  // date, so the entry stays green on evidence of any age. Assert the blanket invariant,
+  // not the entries that happen to have one today.
+  it('every corroborating source carries a published date (evidence-age rule has teeth)', () => {
+    for (const e of reg.entries) {
+      if (!Array.isArray(e.sources)) continue;
+      e.sources.forEach((s, i) => {
+        assert.match(
+          String(s && s.published),
+          /^\d{4}-\d{2}-\d{2}$/,
+          `${e.id} sources[${i}] (${s && s.url}) missing a parseable published date`
+        );
+      });
+    }
+  });
+
+  it('carries the model-routing entries (C1), each dated by a published source', () => {
+    for (const id of ['BP-MODEL-001', 'BP-MODEL-002']) {
+      const e = getEntry(reg, id);
+      assert.ok(e, `${id} missing from the bundled register`);
+      assert.equal(e.confidence, 'confirmed', `${id} must be confirmed`);
+      assert.equal(e.category, 'model-fit', `${id} wrong category`);
+      assert.ok(
+        e.source.url.startsWith('https://code.claude.com/docs/'),
+        `${id} primary source must be the official docs, got ${e.source.url}`
+      );
+      assert.ok(
+        Array.isArray(e.sources) && e.sources.some((s) => s.published),
+        `${id} must carry a corroborating source with a published date (B1 evidence-age rule)`
+      );
+    }
+  });
 });
 
 describe('validateRegister (negative cases)', () => {