feat(linkedin-studio): second-brain SB-S0 foundation — brain/ scaffold + profile fold + id/provenance spine [skip-docs]

SB-S0 (Foundation) of the second-brain arc: a new TS package scripts/brain/
(structural copy of specifics-bank) establishing the spine later slices hang on.
TDD throughout (failing test first); fold scope = P1+P2 only per operator decision.

- types.ts: one provenance vocab (human|published|ai-draft) + the six-field
  ProfileFact record + two-layer ProfileDoc.
- id.ts: slugify + mintEntityId (sha256[:12], kind-namespaced, slug-keyed so the
  id is stable across value edits) + normalizeProvenance (throws on unknown). [SC4]
- profile.ts: no-YAML line-grammar parse/serialize (parse∘serialize = identity over
  the whole doc; values may contain ]/|/quotes) [SC2] + foldUserProfile: lossless,
  idempotent, source-absent-aware fold of config/user-profile.template.md. Pinned
  extraction — P1 labeled scalars (group-headers skipped, [placeholder]→empty) + P2
  expertise group; stops at "### Research Tooling" so deferred explainer prose can't
  leak in as fields. Checkbox-prefs (Goals/Tone/MCPs/Assets) deferred (§8). [SC3]
- dataRoot.ts: inline per-package resolver (repo idiom; no new seam → SC6).
- scaffold.ts/cli.ts: idempotent `brain init` — brain/{index,profile,operations}.md
  + journal/ + ingest/{inbox,published} under the data-dir; compare-then-skip, never
  clobbers a user edit. No session-start wiring (SB-S2 owns it). [SC1]

Gate: new BRAIN floor in test-runner.sh (34 tests; trends/specifics/contract floors
unchanged) + anti-erosion floor 74→75. Full gate 90/0/0, tsc --noEmit clean. [SC5/SC6]
No new command/agent/reference → no version bump, no structure-count change.

Refs docs/second-brain/{brief,plan-sb-s0,architecture}.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RigJBiRFNtFZKCz21qNbQ4

scripts/test-runner.sh

@@ -695,6 +695,34 @@ fi
 
 echo ""
 
+# --- Section 16b: Brain Foundation (SB-S0) ---
+echo "--- Brain Foundation ---"
+
+# The second-brain foundation (scripts/brain, SB-S0) ships the brain/ scaffold
+# initialiser, the two-layer profile.md line-grammar, the lossless+idempotent
+# user-profile fold, and the canonical entity-id + provenance module. This is the
+# spine later slices hang on (the id threads through tributaries in SB-S3, the
+# evolution loop consumes the profile in SB-S2), so the suite stays green and its
+# case count never erodes. KTG-internal: skipped (warn, never fail) for an adopter
+# that ships no brain deps. Same set +e / subshell discipline as Sections 14-16
+# (bash 3.2-safe; keeps a red npm test from aborting the runner under set -e).
+BR_DIR="scripts/brain"
+if [ -x "$BR_DIR/node_modules/.bin/tsx" ]; then
+  BR_OUT=$( set +e; (cd "$BR_DIR" && npm test) 2>&1; echo "BR_EXIT:$?" )
+  BR_EXIT=$(echo "$BR_OUT" | grep -oE 'BR_EXIT:[0-9]+' | grep -oE '[0-9]+' | head -1)
+  BR_TESTS=$(echo "$BR_OUT" | grep -oE 'tests [0-9]+' | grep -oE '[0-9]+' | tail -1)
+  BRAIN_TESTS_FLOOR=34  # SB-S0: id(11) + profile(6) + fold(12) + scaffold(5)
+  if [ "$BR_EXIT" = "0" ] && [ -n "$BR_TESTS" ] && [ "$BR_TESTS" -ge "$BRAIN_TESTS_FLOOR" ]; then
+    pass "brain suite green: $BR_TESTS tests pass (floor $BRAIN_TESTS_FLOOR)"
+  else
+    fail "brain suite NOT green (exit=${BR_EXIT:-?}, tests=${BR_TESTS:-?}, floor $BRAIN_TESTS_FLOOR) — run: (cd $BR_DIR && npm test)"
+  fi
+else
+  warn "brain skipped — deps absent ($BR_DIR/node_modules); run: (cd $BR_DIR && npm install)"
+fi
+
+echo ""
+
 # --- Section 17: De-Niche Guard (B-S1 + B-S2) ---
 echo "--- De-Niche Guard ---"
 
@@ -764,14 +792,15 @@ echo ""
 
 # --- Section 18: Assertion-Count Anti-Erosion (SC6) ---
 # The lint self-modifies its own checks, so a green run could mask a silently dropped
-# assertion. Pin the pre-M0 total (74 pass()+fail() invocations) as a floor; the count
-# may only grow (brief-reviewer assumption 3). Runs last so TOTAL_CHECKS sees every prior check.
-ASSERT_BASELINE_PRE_M0=74
+# assertion. Pin the total pass()+fail() invocations as a monotonic floor; the count
+# may only grow (brief-reviewer assumption 3). History: 74 pre-M0; +1 for the SB-S0
+# brain-suite floor (Section 16b) = 75. Runs last so TOTAL_CHECKS sees every prior check.
+ASSERT_BASELINE_FLOOR=75
 TOTAL_CHECKS=$((PASS + FAIL))
-if [ "$TOTAL_CHECKS" -ge "$ASSERT_BASELINE_PRE_M0" ]; then
-  pass "assertion-count anti-erosion: $TOTAL_CHECKS checks >= pre-M0 baseline $ASSERT_BASELINE_PRE_M0"
+if [ "$TOTAL_CHECKS" -ge "$ASSERT_BASELINE_FLOOR" ]; then
+  pass "assertion-count anti-erosion: $TOTAL_CHECKS checks >= baseline floor $ASSERT_BASELINE_FLOOR"
 else
-  fail "assertion count $TOTAL_CHECKS < pre-M0 baseline $ASSERT_BASELINE_PRE_M0 — a check was silently removed"
+  fail "assertion count $TOTAL_CHECKS < baseline floor $ASSERT_BASELINE_FLOOR — a check was silently removed"
 fi
 
 echo ""