Finding 4: full-trace evidence — reconstructed and re-derived, not summarized

Removes the deferral. Each sampled execution's FULL trace (every graph edge,
count, weight) and delta are persisted as evidence; the independent attestor
reconstructs them, recomputes the canonical trace hash and delta hash, re-derives
the replay-record leaf, and confirms it is among the retained Merkle leaves the
root is built from. The behavior-fingerprint hash is re-derived from features
(not trusted), and f64 divergence is stored bit-exact for an identical hash.

- trace_model: ExecutionTrace::serialize/deserialize (round-trips canonical_hash;
  total on garbage). Test: full_trace_serialize_roundtrips_canonical_hash.
- world_model: WorldDelta::serialize/deserialize (round-trips hash).
- ci_reports: retains TRACE_EVIDENCE_SAMPLE full traces; writes
  evidence/traces.tsv.
- attestation: depends on trace_model/world_model; reconstructs each trace,
  recomputes the leaf, requires it to match the claimed leaf AND be a retained
  leaf. Negative control: tampered_trace_breaks_attestation (corrupting the full
  trace, leaving the claimed leaf, fails attestation).
- merge-gates: requires evidence/traces.tsv; the separate attest step verifies it.

End-to-end (fast profile): 256/256 full traces reconstructed and re-derived to
retained leaves; recomputed root matches the claim over 6600 leaves.

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

crates/ci_reports/src/main.rs

@@ -59,6 +59,28 @@ fn write_evidence(dir: &Path, r: &CiResults) {
         r.provenance.engines_agree,
     );
     fs::write(ev.join("claims.tsv"), claims).expect("write claims");
+
+    // Full-trace evidence (finding 4): each line is
+    //   ws ps cs prs future leaf <TAB> <full trace> <TAB> <full delta>
+    // The attestor reconstructs the trace + delta, recomputes the canonical
+    // trace hash and the replay-record leaf, and checks the leaf is among the
+    // retained leaves. This is the full trace, not a summary.
+    let mut traces = String::from("# full-trace evidence: header<TAB>trace<TAB>delta\n");
+    for ev_rec in &r.trace_evidence {
+        let rr = &ev_rec.replay;
+        traces.push_str(&format!(
+            "{:016x} {:016x} {:016x} {:016x} {:016x} {:016x}\t{}\t{}\n",
+            rr.world_seed,
+            rr.program_seed,
+            rr.contract_seed,
+            rr.perturbation_seed,
+            rr.future_hash.0,
+            rr.hash().0,
+            ev_rec.trace.serialize(),
+            ev_rec.delta.serialize(),
+        ));
+    }
+    fs::write(ev.join("traces.tsv"), traces).expect("write traces");
 }
 
 fn build_reports(dir: &Path, r: &CiResults) {