feat(log): log authority is the fleet default — adopt-at-open, oracle-gated; plus the power-cut throw-site cures and the loud torn-record contract

THE DEFAULT FLIP (ruled on proven evidence — at-ack survived 301/301
acked-writes-through-power-cut in block-layer fault injection; deferred
tree authority demonstrably loses flush-covered acks): a brain with NO
stored authority artifact now ADOPTS LOG AUTHORITY AT OPEN. The oracle
gates the flip exactly as the guarded adoption path always did — curable
divergences baseline-backfilled, the flip lands ONLY on a green verdict —
and a brain that cannot verify STAYS tree-authoritative loudly, with the
refusal recorded on the switch artifact so subsequent opens are cheap.
config logAuthority: 'defer' is the explicit documented opt-out (no
automatic adoption; declared flush-window loss; adoptLogAuthority() flips
later). A stored artifact always wins. RELEASES.md carries the posture.

Two standing .fails debt pins FLIP TO HOLDING under the default: the
at-ack crash-survival gap and the ack-at-log durability target — both now
permanent asserted truths, not aspirations.

POWER-CUT THROW SITES (fault-injection findings, brainy-alone config):
- A manifest-listed-but-unloadable column segment QUARANTINES at
  discovery (loud once, counted always, quarantinedSegments() exposed for
  the heal) and the field serves its remaining segments DEGRADED — never
  a raw throw killing every query on the field. Real storage faults still
  propagate untouched.
- Torn generation artifacts (NaN/garbage in manifest or counter) DISCARD
  with narration at the store's open and recovery re-derives — plus a
  defensive finite-integer guard at the init consumer. Never a RangeError
  killing an open.

THE LOUD TORN-RECORD CONTRACT: an existing-but-unparseable stored record
now surfaces as a typed, counted TornRecordError on every entity-read
surface (including fifteen previously-blind per-item batch catches);
ENOENT stays clean-absent; artifact readers with designed absent-recovery
keep null-tolerance behind the loud floor. Disk corruption can no longer
read as silent data invisibility.

Suite migration: the default's pins inverted deliberately, generation
baselines made relative, quarantine-contract pins rewritten to the ruled
behavior.

Gates: tsc 0 · unit 2065/2065 (159 files) · integration 826 (93 files) ·
conformance 31/31 · kill-matrix 15/15 · torn-open guards 2/2.

src/types/brainy.types.ts

@@ -2084,6 +2084,28 @@ export interface BrainyConfig {
    * `'manual'` restores the pre-9.1 behavior: the engine never flushes on
    * its own (except at `close()`); the caller owns the cadence.
    */
+  /**
+   * Storage-authority posture at open (10.0.0+ fleet default: `'adopt'`).
+   *
+   * `'adopt'` — a brain with NO stored authority artifact adopts LOG
+   * AUTHORITY at open, oracle-gated: the verification oracle replays the
+   * generation log against stored truth; curable divergences (pre-log
+   * rows, witness drift) are baseline-backfilled; the brain flips ONLY on
+   * a green verdict and writes the durable per-brain switch. On green,
+   * writes become durable-at-ack (group-committed log fsync covers every
+   * ack). A brain whose oracle cannot go green STAYS tree-authoritative,
+   * says so loudly, and records the refusal — never a silent half-state.
+   *
+   * `'defer'` — the explicit opt-out: no automatic adoption; the brain
+   * stays tree-authoritative until `adoptLogAuthority()` is called. The
+   * pre-10 behavior, documented for operators who stage their own flips.
+   *
+   * A STORED artifact always wins over this setting (checked-at-open law):
+   * an already-flipped brain stays flipped; an explicitly-recorded tree
+   * posture is honored until an operator re-runs adoption.
+   */
+  logAuthority?: 'adopt' | 'defer'
+
   persistence?: {
     policy?: 'auto' | 'manual'
     /** Background flush after this many committed writes (default 512). */