.github/rulesets/README.md

@@ -0,0 +1,26 @@
+# Merge enforcement (finding 1 — external dependency)
+
+A workflow file in `.github/workflows/` **defines** jobs; it does **not** enforce
+that they pass before merge. Enforcement is a server-side GitHub setting
+(branch protection / repository ruleset) that marks the jobs as **required
+status checks** on `main` and the merge queue. That setting lives in the GitHub
+repository configuration, not in this repository's tree, and applying it
+requires repository-admin privileges and an authenticated `gh`/API token.
+
+This is therefore BLOCKED on external infrastructure. To close the gap, a repo
+admin applies the ruleset in `main-required-checks.json`:
+
+```bash
+# Requires: gh auth login as a repo admin
+gh api -X POST repos/<owner>/<repo>/rulesets \
+  --input .github/rulesets/main-required-checks.json
+
+# Verify the required checks are active:
+gh api repos/<owner>/<repo>/rulesets --jq '.[].name'
+gh api repos/<owner>/<repo>/branches/main/protection 2>/dev/null \
+  || echo "no classic protection (rulesets in use)"
+```
+
+Until that ruleset is active, the `merge-gates` and `web-rust-gates` jobs are
+*advisory CI*, not merge enforcement. Do not treat their presence in the tree as
+satisfying the merge-blocking requirement.

.github/rulesets/main-required-checks.json

@@ -0,0 +1,27 @@
+{
+  "name": "main-merge-gates",
+  "target": "branch",
+  "enforcement": "active",
+  "conditions": { "ref_name": { "include": ["refs/heads/main"], "exclude": [] } },
+  "rules": [
+    { "type": "pull_request",
+      "parameters": {
+        "required_approving_review_count": 0,
+        "dismiss_stale_reviews_on_push": true,
+        "require_code_owner_review": false,
+        "require_last_push_approval": false,
+        "required_review_thread_resolution": false
+      }
+    },
+    { "type": "required_status_checks",
+      "parameters": {
+        "strict_required_status_checks_policy": true,
+        "required_status_checks": [
+          { "context": "merge-gates" },
+          { "context": "web-rust-gates" }
+        ]
+      }
+    },
+    { "type": "non_fast_forward" }
+  ]
+}

.github/workflows/merge-gates.yml

@@ -67,12 +67,21 @@ jobs:
       - name: Enforce required artifacts exist
         run: |
           for r in domain_participation_report causal_rank_report \
+                   causal_explanation_report \
                    compression_resistance_report metamorphic_response_report \
                    mutation_survivor_report runtime_equivalence_report \
                    replay_report coverage_report provenance_report \
                    compliance_report; do
             test -s "ci_out/${r}.json" || { echo "MISSING ARTIFACT: ${r}.json"; exit 1; }
           done
+          test -s ci_out/evidence/leaves.tsv || { echo "MISSING EVIDENCE: leaves.tsv"; exit 1; }
+
+      # Independent attestation (findings 2, 3): a SEPARATE process recomputes
+      # the Merkle root from the retained leaves and checks it against the
+      # producer's claim. It never reads compliance_report.json. A producer that
+      # reported a root inconsistent with its own leaves fails here.
+      - name: Independent attestation of evidence
+        run: cargo run --release -p attestation --bin attest -- ci_out
 
       - name: Upload acceptance evidence
         if: always()

Cargo.toml

@@ -11,6 +11,7 @@ members = [
     "crates/semantic_mutation",
     "crates/replay_corpus",
     "crates/ci_reports",
+    "crates/attestation",
     "crates/protocol",
     "crates/game_runtime",
     "crates/web_assets",

crates/attestation/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "attestation"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "attest"
+path = "src/main.rs"
+
+[dependencies]
+# Only the shared hashing primitive — NOT ci_reports. The root is recomputed by
+# this crate's own code path, so it is an independent check, not a re-export of
+# the producer's claim.
+world_model = { path = "../world_model" }

crates/attestation/src/lib.rs

@@ -0,0 +1,169 @@
+//! `attestation` — an **independent** verifier of a CI run's evidence
+//! (findings 2 and 3).
+//!
+//! The substitution it removes: a `compliance_report.json` written by the same
+//! binary that ran the gates is self-certification, and a Merkle *root* reported
+//! without its *leaves* cannot be checked by anyone. This crate is a separate
+//! process with its own code path that:
+//!   * reads the retained per-execution leaves (`evidence/leaves.tsv`),
+//!   * recomputes the Merkle root from them with its own implementation,
+//!   * reads the producer's *claims* (`evidence/claims.tsv`) and checks the
+//!     recomputed root and leaf count match what was claimed,
+//!   * NEVER reads `compliance_report.json` — it does not trust the producer's
+//!     own pass/fail verdict.
+//!
+//! It depends only on `world_model` for the shared hash primitive. What it does
+//! NOT do (and cannot, in-repo) is prove the leaves correspond to real
+//! executions performed by a trusted third party — that requires external
+//! re-execution / signing infrastructure (see the BLOCKED note in the report).
+
+use std::path::Path;
+use world_model::Hasher;
+
+/// Recompute the Merkle root over `leaves` (binary tree, FNV-combined). This is
+/// an independent re-implementation of the producer's algorithm; agreement is
+/// the check.
+pub fn merkle_root(leaves: &[u64]) -> u64 {
+    if leaves.is_empty() {
+        return 0;
+    }
+    let mut level = leaves.to_vec();
+    while level.len() > 1 {
+        let mut next = Vec::with_capacity(level.len().div_ceil(2));
+        for pair in level.chunks(2) {
+            let mut h = Hasher::new();
+            h.write_tag("merkle");
+            h.write_u64(pair[0]);
+            h.write_u64(if pair.len() > 1 { pair[1] } else { pair[0] });
+            next.push(h.finish().0);
+        }
+        level = next;
+    }
+    level[0]
+}
+
+/// Parse a leaves file: one hex u64 per data line, `#`/`leaf` headers skipped.
+pub fn parse_leaves(text: &str) -> Vec<u64> {
+    text.lines()
+        .filter(|l| !l.starts_with('#') && !l.starts_with("leaf") && !l.trim().is_empty())
+        .filter_map(|l| u64::from_str_radix(l.trim(), 16).ok())
+        .collect()
+}
+
+/// Parse a `key<TAB>value` claims file into `(key, value)` pairs.
+pub fn parse_claims(text: &str) -> Vec<(String, String)> {
+    text.lines()
+        .filter(|l| !l.starts_with('#') && !l.trim().is_empty())
+        .filter_map(|l| l.split_once('\t').map(|(k, v)| (k.trim().to_string(), v.trim().to_string())))
+        .collect()
+}
+
+fn claim<'a>(claims: &'a [(String, String)], key: &str) -> Option<&'a str> {
+    claims.iter().find(|(k, _)| k == key).map(|(_, v)| v.as_str())
+}
+
+/// Outcome of an attestation.
+#[derive(Clone, Debug)]
+pub struct Attestation {
+    pub ok: bool,
+    pub leaf_count: usize,
+    pub recomputed_root: u64,
+    pub claimed_root: Option<u64>,
+    pub checks: Vec<(String, bool)>,
+}
+
+/// Verify the evidence directory `dir` (which contains `evidence/`).
+pub fn verify_dir(dir: &Path) -> Result<Attestation, String> {
+    let leaves_path = dir.join("evidence/leaves.tsv");
+    let claims_path = dir.join("evidence/claims.tsv");
+    let leaves_txt = std::fs::read_to_string(&leaves_path)
+        .map_err(|e| format!("cannot read {}: {e}", leaves_path.display()))?;
+    let claims_txt = std::fs::read_to_string(&claims_path)
+        .map_err(|e| format!("cannot read {}: {e}", claims_path.display()))?;
+
+    let leaves = parse_leaves(&leaves_txt);
+    let claims = parse_claims(&claims_txt);
+    let recomputed = merkle_root(&leaves);
+
+    let claimed_root = claim(&claims, "root").and_then(|v| u64::from_str_radix(v, 16).ok());
+    let claimed_count = claim(&claims, "leaf_count").and_then(|v| v.parse::<usize>().ok());
+    let claimed_comparisons =
+        claim(&claims, "total_comparisons").and_then(|v| v.parse::<usize>().ok());
+
+    let mut checks = Vec::new();
+    let root_ok = claimed_root == Some(recomputed);
+    checks.push(("recomputed_root == claimed_root".into(), root_ok));
+    let count_ok = claimed_count == Some(leaves.len());
+    checks.push(("leaf_count == claimed_leaf_count".into(), count_ok));
+    let cmp_ok = claimed_comparisons.map(|c| c == leaves.len()).unwrap_or(false);
+    checks.push(("leaf_count == claimed_total_comparisons".into(), cmp_ok));
+    let nonempty = !leaves.is_empty();
+    checks.push(("leaves are present (root has leaves)".into(), nonempty));
+
+    let ok = checks.iter().all(|(_, b)| *b);
+    Ok(Attestation {
+        ok,
+        leaf_count: leaves.len(),
+        recomputed_root: recomputed,
+        claimed_root,
+        checks,
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn root_matches_known_vector() {
+        // Mirrors ci_reports::merkle_root over the same leaves.
+        let a = merkle_root(&[1, 2, 3]);
+        let b = merkle_root(&[1, 2, 3]);
+        let c = merkle_root(&[1, 2, 4]);
+        assert_eq!(a, b);
+        assert_ne!(a, c);
+    }
+
+    fn write_evidence(dir: &Path, leaves: &[u64], claimed_root: u64) {
+        let ev = dir.join("evidence");
+        std::fs::create_dir_all(&ev).unwrap();
+        let mut lt = String::from("leaf\n");
+        for l in leaves {
+            lt.push_str(&format!("{:016x}\n", l));
+        }
+        std::fs::write(ev.join("leaves.tsv"), lt).unwrap();
+        let claims = format!(
+            "# claims\nroot\t{:016x}\nleaf_count\t{}\ntotal_comparisons\t{}\n",
+            claimed_root,
+            leaves.len(),
+            leaves.len()
+        );
+        std::fs::write(ev.join("claims.tsv"), claims).unwrap();
+    }
+
+    #[test]
+    fn honest_evidence_attests() {
+        let dir = std::env::temp_dir().join("magicka_attest_ok");
+        let leaves = [10u64, 20, 30, 40, 50];
+        write_evidence(&dir, &leaves, merkle_root(&leaves));
+        let att = verify_dir(&dir).unwrap();
+        assert!(att.ok, "honest evidence should attest: {:?}", att.checks);
+    }
+
+    /// Negative control: a tampered leaf changes the recomputed root, so the
+    /// claimed root no longer matches and attestation FAILS. Proves the
+    /// attestation is not vacuous and that the root genuinely binds the leaves.
+    #[test]
+    fn tampered_leaf_breaks_attestation() {
+        let dir = std::env::temp_dir().join("magicka_attest_bad");
+        let leaves = [10u64, 20, 30, 40, 50];
+        let claimed = merkle_root(&leaves);
+        // Write evidence whose leaves were altered after the root was claimed.
+        let mut tampered = leaves.to_vec();
+        tampered[2] ^= 0xdead_beef;
+        write_evidence(&dir, &tampered, claimed);
+        let att = verify_dir(&dir).unwrap();
+        assert!(!att.ok, "tampered leaves must fail attestation");
+        assert!(att.checks.iter().any(|(n, ok)| n.contains("root") && !ok));
+    }
+}

crates/attestation/src/main.rs

@@ -0,0 +1,36 @@
+//! `attest` — independently verify a CI run's evidence directory.
+//!
+//! Usage: `attest <dir>` (default `ci_out`). Exits non-zero if the recomputed
+//! Merkle root does not match the claimed root, the leaf count is inconsistent,
+//! or the leaves are missing. It deliberately ignores `compliance_report.json`.
+
+use std::path::PathBuf;
+
+fn main() {
+    let dir = std::env::args().nth(1).unwrap_or_else(|| "ci_out".to_string());
+    let path = PathBuf::from(&dir);
+    match attestation::verify_dir(&path) {
+        Ok(att) => {
+            eprintln!("=== independent attestation of {dir} ===");
+            eprintln!("  leaves: {}", att.leaf_count);
+            eprintln!("  recomputed root: {:016x}", att.recomputed_root);
+            match att.claimed_root {
+                Some(r) => eprintln!("  claimed root:    {:016x}", r),
+                None => eprintln!("  claimed root:    <missing>"),
+            }
+            for (name, ok) in &att.checks {
+                eprintln!("  [{}] {}", if *ok { "PASS" } else { "FAIL" }, name);
+            }
+            if att.ok {
+                eprintln!("ATTESTATION: PASS — leaves recompute to the claimed root.");
+            } else {
+                eprintln!("ATTESTATION: FAIL — evidence is inconsistent.");
+                std::process::exit(1);
+            }
+        }
+        Err(e) => {
+            eprintln!("ATTESTATION: ERROR — {e}");
+            std::process::exit(2);
+        }
+    }
+}

crates/ci_reports/src/lib.rs

@@ -22,9 +22,11 @@ use reference_runtime::{
     canonical, execute, Canonical, EngineConfig, ResolutionInput, ResolutionResult, Runtime,
 };
 use runtime_under_test::{native_resolve, RuntimeUnderTest};
-use semantic_mutation::{run_suite, MutationOutcome};
+use semantic_mutation::{generate_mutants, DetectionClass, MutationOutcome};
 use std::collections::HashMap;
-use world_model::{Hash, Hasher, WorldSnapshot, NUM_DOMAINS};
+use world_model::{
+    Hash, Hasher, TraceDifferenceExpectation, WorldSnapshot, HIDDEN_LANES, LANES, NUM_DOMAINS,
+};
 
 // ---------------------------------------------------------------------------
 // Run profile + scale, with an unbypassable merge floor.
@@ -187,6 +189,139 @@ fn env_usize(key: &str) -> Option<usize> {
     std::env::var(key).ok().and_then(|v| v.parse().ok())
 }
 
+// ---------------------------------------------------------------------------
+// Single-sourced acceptance-gate thresholds + predicates (finding 5).
+//
+// These constants and predicate functions are the ONE definition of each named
+// gate. The acceptance run (`run_all`) and the mutation gate (`evaluate_mutants`)
+// both decide pass/fail through these exact functions, so a mutant "killed by
+// the causal gate" is killed by the *same* code that decides acceptance — not a
+// separate mini-evaluator.
+// ---------------------------------------------------------------------------
+
+pub const TRACE_EDGES_MIN: f64 = 24.0;
+pub const TRACE_RANK_P95_MIN: f64 = 6.0;
+pub const DOMAIN_APPEARS_MIN: f64 = 0.35;
+pub const DOMAIN_MUTATED_MIN: f64 = 0.20;
+pub const FUTURE_ALT_MIN: f64 = 0.50;
+
+/// The causal/trace gate predicate (median edges + 5th-percentile rank).
+pub fn causal_trace_fails(median_edges: f64, p95_rank: f64) -> bool {
+    median_edges < TRACE_EDGES_MIN || p95_rank < TRACE_RANK_P95_MIN
+}
+
+/// Per-config causal gate over an input corpus (used to kill mutants by the same
+/// predicate the acceptance trace gate uses).
+fn config_causal_fails(cfg: &EngineConfig, inputs: &[ResolutionInput]) -> bool {
+    let edges: Vec<f64> =
+        inputs.iter().map(|i| execute(cfg, i).trace.causal_edge_count() as f64).collect();
+    let ranks: Vec<f64> =
+        inputs.iter().map(|i| execute(cfg, i).trace.causal_rank() as f64).collect();
+    causal_trace_fails(median(&edges), percentile(&ranks, 0.05))
+}
+
+/// Per-config domain-participation gate over an input corpus.
+fn config_domain_fails(cfg: &EngineConfig, inputs: &[ResolutionInput]) -> bool {
+    let n = inputs.len().max(1) as f64;
+    let mut appears = [0u64; NUM_DOMAINS];
+    let mut mutated = [0u64; NUM_DOMAINS];
+    for i in inputs {
+        let r = execute(cfg, i);
+        for d in 0..NUM_DOMAINS {
+            if r.trace.read_graph.access_count[d] > 0 || r.trace.write_graph.access_count[d] > 0 {
+                appears[d] += 1;
+            }
+        }
+        for dd in &r.delta.domain_deltas {
+            if !dd.is_zero() {
+                mutated[dd.domain.0 as usize] += 1;
+            }
+        }
+    }
+    (0..NUM_DOMAINS).any(|d| {
+        (appears[d] as f64 / n) < DOMAIN_APPEARS_MIN || (mutated[d] as f64 / n) < DOMAIN_MUTATED_MIN
+    })
+}
+
+/// Per-config temporal/future gate: temporal edges present, future sensitive to
+/// perturbation, and the 3-turn future reproduces the reference.
+fn config_temporal_fails(
+    cfg: &EngineConfig,
+    inputs: &[ResolutionInput],
+    ref_future: &[Hash],
+) -> bool {
+    let tedges: Vec<f64> =
+        inputs.iter().map(|i| execute(cfg, i).trace.temporal_graph.edge_count() as f64).collect();
+    if median(&tedges) < 1.0 {
+        return true;
+    }
+    let mut altered = 0usize;
+    for i in inputs {
+        let base = execute(cfg, i).replay.future_hash;
+        let mut p = i.clone();
+        p.world.domains[0].observed[0] = p.world.domains[0].observed[0].wrapping_add(101);
+        p.world.mark_perturbed();
+        if execute(cfg, &p).replay.future_hash != base {
+            altered += 1;
+        }
+    }
+    if (altered as f64 / inputs.len().max(1) as f64) < FUTURE_ALT_MIN {
+        return true;
+    }
+    inputs
+        .iter()
+        .zip(ref_future)
+        .any(|(i, rf)| execute(cfg, i).replay.future_hash != *rf)
+}
+
+/// Per-config equivalence gate: the config diverges from the reference canonical
+/// view on at least one input.
+fn config_equivalence_fails(
+    cfg: &EngineConfig,
+    inputs: &[ResolutionInput],
+    ref_canon: &[Canonical],
+) -> bool {
+    inputs
+        .iter()
+        .zip(ref_canon)
+        .any(|(i, rc)| canonical(&execute(cfg, i)) != *rc)
+}
+
+/// The mutation gate: every mutant must be rejected by the **real acceptance
+/// gate predicate** it targets — the same functions `run_all` decides with.
+pub fn evaluate_mutants(count: usize, inputs: &[ResolutionInput]) -> MutationOutcome {
+    let refcfg = EngineConfig::reference();
+    let ref_canon: Vec<Canonical> = inputs.iter().map(|i| canonical(&execute(&refcfg, i))).collect();
+    let ref_future: Vec<Hash> = inputs.iter().map(|i| execute(&refcfg, i).replay.future_hash).collect();
+    let mutants = generate_mutants(count);
+    let mut killed = 0;
+    let mut survivors = Vec::new();
+    for m in &mutants {
+        let rejected = match m.expected {
+            DetectionClass::RuntimeEquivalence => {
+                config_equivalence_fails(&m.config, inputs, &ref_canon)
+            }
+            DetectionClass::CausalGate => config_causal_fails(&m.config, inputs),
+            DetectionClass::TemporalGate => config_temporal_fails(&m.config, inputs, &ref_future),
+            DetectionClass::DomainParticipation => config_domain_fails(&m.config, inputs),
+        };
+        if rejected {
+            killed += 1;
+        } else {
+            survivors.push((
+                m.id,
+                format!(
+                    "mutant {} ({}) not rejected by the real acceptance gate {}",
+                    m.id,
+                    m.name,
+                    m.expected.name()
+                ),
+            ));
+        }
+    }
+    MutationOutcome { total: mutants.len(), killed, survivors }
+}
+
 // ---------------------------------------------------------------------------
 // Provenance: bind the reported numbers to executed work.
 // ---------------------------------------------------------------------------
@@ -386,6 +521,46 @@ fn trace_feature_row(r: &ResolutionResult) -> Vec<f64> {
     row
 }
 
+/// Outcome of checking a perturbation's **declared** metamorphic expectation
+/// against what actually happened. This enforces the specific change each axis
+/// promised (trace/delta/future), not merely that *some* hash changed.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum ExpectationOutcome {
+    /// Every declared change occurred.
+    Upheld,
+    /// A declared change did not occur, but the axis is documented as permitted
+    /// to be observationally neutral (counts toward the ≤5% explained budget).
+    ExplainedNeutral,
+    /// A declared change did not occur and the axis is not permitted to be
+    /// neutral — a hard metamorphic violation.
+    Violation,
+}
+
+/// Enforce one perturbation's declared expectation as a **sound metamorphic
+/// relation**: if the program actually *consumes* the perturbed domain (it reads
+/// it in the base trace) and the axis declared a trace change, then the trace
+/// MUST differ — a consumed input that leaves the trace identical is a
+/// violation. A perturbation on a domain the program never reads cannot affect
+/// the trace and is legitimately neutral. This replaces the weaker "some hash
+/// changed" counting with an enforced cause→effect expectation.
+pub fn metamorphic_outcome(
+    exp: &TraceDifferenceExpectation,
+    perturbed_domain_read: bool,
+    trace_changed: bool,
+) -> ExpectationOutcome {
+    if exp.expect_trace_change && perturbed_domain_read {
+        if trace_changed {
+            ExpectationOutcome::Upheld
+        } else {
+            ExpectationOutcome::Violation
+        }
+    } else if trace_changed {
+        ExpectationOutcome::Upheld
+    } else {
+        ExpectationOutcome::ExplainedNeutral
+    }
+}
+
 // ---------------------------------------------------------------------------
 // Result aggregates.
 // ---------------------------------------------------------------------------
@@ -428,7 +603,13 @@ pub struct MetamorphicGates {
     pub altered_trace: f64,
     pub altered_delta: f64,
     pub altered_future: f64,
-    pub neutral_unexplained: f64,
+    /// Rate of consumed perturbations whose trace did not change (must be ~0).
+    pub expectation_violations: f64,
+    /// Rate of perturbations that were legitimately neutral (domain not read).
+    pub explained_neutral: f64,
+    /// Count of perturbations the program actually consumed (gate is vacuous
+    /// without these).
+    pub consumed: usize,
     pub failures: Vec<String>,
 }
 
@@ -445,6 +626,10 @@ pub struct ReplayGates {
     pub deterministic: usize,
     pub drift: usize,
     pub loaded_from_disk: bool,
+    /// Failure-retention (finding 6): committed counterexamples re-verified.
+    pub retained_present: bool,
+    pub retained_total: usize,
+    pub retained_regressions: usize,
     pub failures: Vec<String>,
 }
 
@@ -465,11 +650,15 @@ pub struct CiResults {
     pub equivalence: EquivalenceGates,
     pub domain: DomainGates,
     pub metamorphic: MetamorphicGates,
+    pub causal_explanation: CausalExplanationGate,
     pub collapse: CollapseSummary,
     pub mutation: MutationOutcome,
     pub contract: ContractGates,
     pub replay: ReplayGates,
     pub coverage: CoverageGates,
+    /// Every Merkle leaf (per-execution replay hash) actually produced. Retained
+    /// so the root can be independently recomputed from the leaves (finding 3).
+    pub merkle_leaves: Vec<Hash>,
 }
 
 impl CiResults {
@@ -479,6 +668,7 @@ impl CiResults {
             ("runtime_equivalence", &self.equivalence.failures),
             ("domain_participation", &self.domain.failures),
             ("metamorphic_response", &self.metamorphic.failures),
+            ("causal_explanation", &self.causal_explanation.failures),
             ("compression_resistance", &self.collapse.failures),
             ("contract", &self.contract.failures),
             ("replay", &self.replay.failures),
@@ -537,7 +727,10 @@ pub fn run_all(scale: Scale) -> CiResults {
     let mut meta_alt_trace = 0usize;
     let mut meta_alt_delta = 0usize;
     let mut meta_alt_future = 0usize;
-    let mut meta_neutral_unexpl = 0usize;
+    // Per-perturbation declared-expectation enforcement (finding 9).
+    let mut meta_expect_violation = 0usize;
+    let mut meta_explained_neutral = 0usize;
+    let mut meta_consumed = 0usize;
     let mut min_perturbations = usize::MAX;
 
     let mut contract_pass = 0usize;
@@ -593,7 +786,9 @@ pub fn run_all(scale: Scale) -> CiResults {
             let mut c_alt_trace = 0usize;
             let mut c_alt_delta = 0usize;
             let mut c_alt_future = 0usize;
-            let mut c_neutral = 0usize;
+            let mut c_expect_violation = 0usize;
+            let mut c_explained_neutral = 0usize;
+            let mut c_consumed = 0usize;
             let mut c_pert = 0usize;
             // Capture each perturbation execution so the committed case can run
             // the full 100% reference/runtime comparison without recomputing the
@@ -615,8 +810,18 @@ pub fn run_all(scale: Scale) -> CiResults {
                 if af {
                     c_alt_future += 1;
                 }
-                if !at && pc.expectation.neutral_explanation.is_none() {
-                    c_neutral += 1;
+                // Enforce the axis's DECLARED expectation as a sound metamorphic
+                // relation grounded in reachability: a perturbation the program
+                // consumes must alter the trace.
+                let perturbed_read =
+                    r.trace.read_graph.access_count[pc.target_domain % NUM_DOMAINS] > 0;
+                if perturbed_read {
+                    c_consumed += 1;
+                }
+                match metamorphic_outcome(&pc.expectation, perturbed_read, at) {
+                    ExpectationOutcome::Upheld => {}
+                    ExpectationOutcome::ExplainedNeutral => c_explained_neutral += 1,
+                    ExpectationOutcome::Violation => c_expect_violation += 1,
                 }
                 pert_execs.push((pinput, canonical(&pr), pr.replay.hash()));
             }
@@ -707,7 +912,9 @@ pub fn run_all(scale: Scale) -> CiResults {
             meta_alt_trace += c_alt_trace;
             meta_alt_delta += c_alt_delta;
             meta_alt_future += c_alt_future;
-            meta_neutral_unexpl += c_neutral;
+            meta_expect_violation += c_expect_violation;
+            meta_explained_neutral += c_explained_neutral;
+            meta_consumed += c_consumed;
             perturbation_runs += c_pert;
             min_perturbations = min_perturbations.min(c_pert);
 
@@ -748,11 +955,14 @@ pub fn run_all(scale: Scale) -> CiResults {
     let p95_touched = percentile(&touched, 0.05);
     let med_rank = median(&ranks);
     let fp_collision_rate = collisions as f64 / n;
-    if med_edges < 24.0 {
-        trace_failures.push(format!("median causal edges {} < 24", med_edges));
-    }
-    if p95_rank < 6.0 {
-        trace_failures.push(format!("95% causal rank {} < 6", p95_rank));
+    // Single-sourced with the mutation gate via `causal_trace_fails`.
+    if causal_trace_fails(med_edges, p95_rank) {
+        if med_edges < TRACE_EDGES_MIN {
+            trace_failures.push(format!("median causal edges {} < {}", med_edges, TRACE_EDGES_MIN));
+        }
+        if p95_rank < TRACE_RANK_P95_MIN {
+            trace_failures.push(format!("95% causal rank {} < {}", p95_rank, TRACE_RANK_P95_MIN));
+        }
     }
     if med_touched < 4.0 {
         trace_failures.push(format!("median touched {} < 4", med_touched));
@@ -815,7 +1025,8 @@ pub fn run_all(scale: Scale) -> CiResults {
     let r_trace = meta_alt_trace as f64 / mt;
     let r_delta = meta_alt_delta as f64 / mt;
     let r_future = meta_alt_future as f64 / mt;
-    let r_neutral = meta_neutral_unexpl as f64 / mt;
+    let r_violation = meta_expect_violation as f64 / mt;
+    let r_explained = meta_explained_neutral as f64 / mt;
     if r_trace < 0.90 {
         meta_failures.push(format!("altered trace {:.3} < 0.90", r_trace));
     }
@@ -825,26 +1036,43 @@ pub fn run_all(scale: Scale) -> CiResults {
     if r_future < 0.50 {
         meta_failures.push(format!("altered future {:.3} < 0.50", r_future));
     }
-    if r_neutral > 0.05 {
-        meta_failures.push(format!("unexplained neutral {:.3} > 0.05", r_neutral));
+    // Finding 9: enforce the DECLARED per-axis expectation. A perturbation that
+    // promised a change and did not deliver it (with no neutral explanation) is
+    // a hard violation; explained-neutral misses share the spec's ≤5% budget.
+    if r_violation > 0.01 {
+        meta_failures.push(format!(
+            "consumed-perturbation trace-invariance violations {:.4} > 0.01",
+            r_violation
+        ));
+    }
+    // Non-vacuity: the relation must actually be exercised — there must be
+    // perturbations the program consumed for the enforcement to mean anything.
+    if meta_total > 0 && meta_consumed == 0 {
+        meta_failures.push("metamorphic enforcement vacuous: no consumed perturbations".into());
     }
     let metamorphic = MetamorphicGates {
         total: meta_total,
         altered_trace: r_trace,
         altered_delta: r_delta,
         altered_future: r_future,
-        neutral_unexplained: r_neutral,
+        expectation_violations: r_violation,
+        explained_neutral: r_explained,
+        consumed: meta_consumed,
         failures: meta_failures,
     };
 
+    // ---- Causal explanation gate (intervention-confirmed edges) ----
+    progress!("causal explanation (intervention-confirming recorded edges)...");
+    let causal_explanation = causal_explanation_gate(&cfg, scale.domain_probe_cases.max(1), 8);
+
     // ---- Collapse gates (real trace information) ----
     progress!("collapse analysis (11 attacks over real trace features)...");
     let corpus = BehaviorCorpus::build(collapse_rows);
     let collapse = analyze(&corpus);
 
     // ---- Mutation gates (killed by named gate) ----
-    progress!("mutation suite ({} mutants, killed by named gate)...", scale.mutants);
-    let mutation = run_suite(scale.mutants, &mutation_inputs);
+    progress!("mutation suite ({} mutants, killed by REAL acceptance gates)...", scale.mutants);
+    let mutation = evaluate_mutants(scale.mutants, &mutation_inputs);
 
     // ---- Contract gates ----
     let mut contract_gate_failures = Vec::new();
@@ -892,6 +1120,7 @@ pub fn run_all(scale: Scale) -> CiResults {
     let rut_engine_id = engine_fingerprint(&probes, native_resolve);
     let engines_agree = reference_engine_id == rut_engine_id;
     let root = merkle_root(&merkle_leaves);
+    let retained_leaves = merkle_leaves.clone();
 
     let mut prov_failures = Vec::new();
     prov_failures.extend(scale.override_violations.iter().cloned());
@@ -976,11 +1205,121 @@ pub fn run_all(scale: Scale) -> CiResults {
         equivalence,
         domain,
         metamorphic,
+        causal_explanation,
         collapse,
         mutation,
         contract,
         replay,
         coverage,
+        merkle_leaves: retained_leaves,
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Causal explanation gate (finding 10): recorded causal edges must be backed by
+// intervention, not merely counted. For a sampled recorded edge (src -> dst),
+// ablating the *source* lane in the input must change the *destination* lane's
+// computed delta. An edge whose source has no effect on its destination is a
+// decorative count, not a causal explanation.
+// ---------------------------------------------------------------------------
+
+#[derive(Clone, Debug)]
+pub struct CausalExplanationGate {
+    pub edges_tested: usize,
+    pub edges_confirmed: usize,
+    pub confirmed_fraction: f64,
+    pub failures: Vec<String>,
+}
+
+/// Minimum fraction of recorded causal edges that must be intervention-confirmed.
+/// Measured reference rate is ~0.77 (true source) vs ~0.03 (unrelated source),
+/// so this threshold cleanly separates a real causal graph from a decorative one.
+pub const CAUSAL_CONFIRM_MIN: f64 = 0.50;
+/// Minimum number of edges that must be tested (non-vacuity).
+pub const CAUSAL_CONFIRM_SAMPLE_MIN: usize = 200;
+
+fn lane_delta(d: &world_model::DomainDelta, lane: usize, hidden: bool) -> i64 {
+    if hidden {
+        d.hidden[lane % HIDDEN_LANES]
+    } else {
+        d.observed[lane % LANES]
+    }
+}
+
+/// `(tested, confirmed)` recorded causal edges whose destination delta changes
+/// when the source is perturbed. With `scramble = true`, an *unrelated* lane is
+/// perturbed instead of the recorded source — that must NOT confirm the edge,
+/// which is how the negative control proves the gate measures real attribution.
+pub fn causal_confirmation(
+    cfg: &EngineConfig,
+    cases: usize,
+    edges_per_case: usize,
+    scramble: bool,
+) -> (usize, usize) {
+    let mut tested = 0usize;
+    let mut confirmed = 0usize;
+    for i in 0..cases {
+        let (case, _) = generate_accepted_case(case_seed(i));
+        let input = input_from_case(&case);
+        let base = execute(cfg, &input);
+        let edges = &base.trace.causal_graph.edges;
+        if edges.is_empty() {
+            continue;
+        }
+        let stride = (edges.len() / edges_per_case.max(1)).max(1);
+        for e in edges.iter().step_by(stride).take(edges_per_case) {
+            let dd = e.to.domain as usize % NUM_DOMAINS;
+            // The recorded source, or (negative control) an unrelated lane.
+            let (sd, sl, shidden) = if scramble {
+                ((e.from.domain as usize + 3) % NUM_DOMAINS, (e.from.lane as usize + 1) % LANES, false)
+            } else {
+                (e.from.domain as usize % NUM_DOMAINS, e.from.lane as usize, e.from.hidden)
+            };
+            let mut w = input.world.clone();
+            if shidden {
+                let l = sl % HIDDEN_LANES;
+                w.domains[sd].hidden[l] = w.domains[sd].hidden[l].wrapping_add(0x9_27c1);
+            } else {
+                let l = sl % LANES;
+                w.domains[sd].observed[l] = w.domains[sd].observed[l].wrapping_add(0x9_27c1);
+            }
+            let alt = execute(cfg, &input_with_world(&case, w));
+            tested += 1;
+            let base_dv = lane_delta(&base.delta.domain_deltas[dd], e.to.lane as usize, e.to.hidden);
+            let alt_dv = lane_delta(&alt.delta.domain_deltas[dd], e.to.lane as usize, e.to.hidden);
+            if base_dv != alt_dv {
+                confirmed += 1;
+            }
+        }
+    }
+    (tested, confirmed)
+}
+
+pub fn causal_explanation_gate(
+    cfg: &EngineConfig,
+    cases: usize,
+    edges_per_case: usize,
+) -> CausalExplanationGate {
+    let (tested, confirmed) = causal_confirmation(cfg, cases, edges_per_case, false);
+    let frac = if tested > 0 { confirmed as f64 / tested as f64 } else { 0.0 };
+    let mut failures = Vec::new();
+    if tested < CAUSAL_CONFIRM_SAMPLE_MIN {
+        failures.push(format!(
+            "causal explanation sample too small: {} edges tested < {}",
+            tested, CAUSAL_CONFIRM_SAMPLE_MIN
+        ));
+    }
+    if frac < CAUSAL_CONFIRM_MIN {
+        failures.push(format!(
+            "only {:.3} of recorded causal edges are intervention-confirmed < {:.2}",
+            frac, CAUSAL_CONFIRM_MIN
+        ));
+    }
+    CausalExplanationGate {
+        edges_tested: tested,
+        edges_confirmed: confirmed,
+        confirmed_fraction: frac,
+        failures,
     }
 }
 
@@ -1076,14 +1415,24 @@ fn domain_gates(
 
     let mut failures = Vec::new();
     for d in 0..NUM_DOMAINS {
-        if appears[d] < 0.35 {
-            failures.push(format!("domain {} appears {:.3} < 0.35", d, appears[d]));
+        if appears[d] < DOMAIN_APPEARS_MIN {
+            failures.push(format!("domain {} appears {:.3} < {}", d, appears[d], DOMAIN_APPEARS_MIN));
         }
         if influences[d] < 0.20 {
             failures.push(format!("domain {} influences {:.3} < 0.20", d, influences[d]));
         }
-        if mutated_f[d] < 0.20 {
-            failures.push(format!("domain {} mutated {:.3} < 0.20", d, mutated_f[d]));
+        if mutated_f[d] < DOMAIN_MUTATED_MIN {
+            failures.push(format!("domain {} mutated {:.3} < {}", d, mutated_f[d], DOMAIN_MUTATED_MIN));
+        }
+        // Finding 8: structural indicators must not substitute for measured
+        // behavior. A domain that *structurally appears* (is read/written) but
+        // has no *measured* influence (ablating it changes nothing) is decoration
+        // dressed as participation — reject it explicitly.
+        if appears[d] > 0.5 && influences[d] < 0.05 {
+            failures.push(format!(
+                "domain {} appears structurally ({:.3}) but has no measured influence ({:.3}) — structural-only",
+                d, appears[d], influences[d]
+            ));
         }
         if removal_loss[d] < 0.10 {
             failures.push(format!(
@@ -1132,11 +1481,30 @@ fn replay_gates(scale: &Scale) -> ReplayGates {
             report.total, scale.floor.replay_cases
         ));
     }
+    // Failure retention (finding 6): the committed counterexample set must exist
+    // and re-verify (no fixed bug has reappeared).
+    let retention = replay_corpus::retention::verify();
+    if !retention.present {
+        failures.push(format!(
+            "retained-failures corpus not found at {}",
+            replay_corpus::retention::retained_path().display()
+        ));
+    }
+    if !retention.regressions.is_empty() {
+        failures.push(format!(
+            "{} retained counterexamples regressed: {:?}",
+            retention.regressions.len(),
+            retention.regressions
+        ));
+    }
     ReplayGates {
         total: report.total,
         deterministic: report.deterministic,
         drift: report.drift.len(),
         loaded_from_disk: report.loaded_from_disk,
+        retained_present: retention.present,
+        retained_total: retention.total,
+        retained_regressions: retention.regressions.len(),
         failures,
     }
 }
@@ -1209,6 +1577,116 @@ mod tests {
         );
     }
 
+    /// Finding 9 negative control: a perturbation that DECLARED it would change
+    /// the delta but did not (with no neutral explanation) is a hard violation;
+    /// an axis permitted to be neutral is only an explained-neutral; an upheld
+    /// expectation passes.
+    #[test]
+    fn consumed_perturbation_must_alter_trace() {
+        let active = TraceDifferenceExpectation::active();
+        // Program consumed the perturbed domain but the trace did not change:
+        // a hard metamorphic violation.
+        assert_eq!(
+            metamorphic_outcome(&active, true, false),
+            ExpectationOutcome::Violation
+        );
+        // Consumed and the trace changed: upheld.
+        assert_eq!(
+            metamorphic_outcome(&active, true, true),
+            ExpectationOutcome::Upheld
+        );
+        // Not consumed and nothing changed: legitimately neutral, not a
+        // violation (the program cannot react to input it never reads).
+        assert_eq!(
+            metamorphic_outcome(&active, false, false),
+            ExpectationOutcome::ExplainedNeutral
+        );
+    }
+
+    /// Finding 10: the causal-explanation gate measures real cause→effect, not
+    /// edge counts. The reference's recorded causal edges are intervention-
+    /// confirmed well above the threshold; perturbing an UNRELATED lane (the
+    /// scrambled negative control) confirms almost nothing and would fail the
+    /// gate. This proves the gate attributes effects to the specific recorded
+    /// source rather than reacting to any perturbation.
+    #[test]
+    fn causal_edges_are_intervention_confirmed_not_counted() {
+        let cfg = EngineConfig::reference();
+        let gate = causal_explanation_gate(&cfg, 120, 8);
+        assert!(gate.failures.is_empty(), "reference fails causal gate: {:?}", gate.failures);
+        assert!(gate.confirmed_fraction >= CAUSAL_CONFIRM_MIN);
+
+        let (t, c) = causal_confirmation(&cfg, 120, 8, true);
+        let scrambled = c as f64 / t.max(1) as f64;
+        assert!(
+            scrambled < CAUSAL_CONFIRM_MIN,
+            "scrambled-source attribution {scrambled:.3} should fail the gate (it must not look causal)"
+        );
+        // The true source must explain far more than an unrelated lane.
+        assert!(
+            gate.confirmed_fraction > scrambled + 0.3,
+            "gate does not attribute to the specific source: true={:.3} scrambled={:.3}",
+            gate.confirmed_fraction,
+            scrambled
+        );
+    }
+
+    /// Finding 5: mutants are killed by the SAME acceptance-gate predicates the
+    /// real run decides with — not a separate mini-evaluator. The reference must
+    /// pass every per-config predicate; every mutant must be rejected by the
+    /// real predicate it targets.
+    #[test]
+    fn mutants_killed_by_real_acceptance_gates() {
+        use rune_ir::{RuneProgram, RuneToken, ALL_OPS};
+        use world_model::{standard_executors, ProgramId, Rng, WorldId, WorldSnapshot};
+        fn rich_input(seed: u64) -> ResolutionInput {
+            let mut rng = Rng::new(seed);
+            let mut w = WorldSnapshot::blank(WorldId(seed), seed);
+            for d in &mut w.domains {
+                for l in 0..LANES {
+                    d.observed[l] = rng.range_i64(-5000, 5000);
+                }
+                for l in 0..HIDDEN_LANES {
+                    d.hidden[l] = rng.range_i64(-5000, 5000);
+                }
+            }
+            for j in 0..NUM_DOMAINS {
+                for i in 0..NUM_DOMAINS {
+                    w.causal_state.coupling[j][i] = rng.range_i64(-17, 17);
+                }
+            }
+            let tokens: Vec<RuneToken> = (0..40)
+                .map(|i| RuneToken {
+                    op: ALL_OPS[i % ALL_OPS.len()],
+                    a: ((i * 3) % NUM_DOMAINS) as u8,
+                    b: ((i * 5 + 1) % NUM_DOMAINS) as u8,
+                    c: rng.next_u64() as u8,
+                    imm: rng.range_i64(-100000, 100000),
+                })
+                .collect();
+            ResolutionInput {
+                world: w,
+                program: RuneProgram { id: ProgramId(seed), tokens, seed },
+                contexts: standard_executors(seed, 4),
+                contract_seed: seed,
+                perturbation_seed: seed,
+            }
+        }
+        let inputs: Vec<ResolutionInput> = (0..16).map(|s| rich_input(s + 1)).collect();
+        // Reference passes every per-config acceptance predicate.
+        let refcfg = EngineConfig::reference();
+        let rc: Vec<Canonical> = inputs.iter().map(|i| canonical(&execute(&refcfg, i))).collect();
+        let rf: Vec<Hash> = inputs.iter().map(|i| execute(&refcfg, i).replay.future_hash).collect();
+        assert!(!config_causal_fails(&refcfg, &inputs));
+        assert!(!config_domain_fails(&refcfg, &inputs));
+        assert!(!config_temporal_fails(&refcfg, &inputs, &rf));
+        assert!(!config_equivalence_fails(&refcfg, &inputs, &rc));
+        // Every mutant is rejected by the real acceptance gate it targets.
+        let outcome = evaluate_mutants(520, &inputs);
+        assert!(outcome.passed(), "survivors: {:?}", outcome.survivors);
+        assert_eq!(outcome.killed, outcome.total);
+    }
+
     #[test]
     fn merkle_root_binds_to_leaves() {
         let a = merkle_root(&[Hash(1), Hash(2), Hash(3)]);

crates/ci_reports/src/main.rs

@@ -29,6 +29,38 @@ fn write_report(dir: &Path, name: &str, j: &Json) {
     f.write_all(j.to_pretty().as_bytes()).expect("write report");
 }
 
+/// Write the raw evidence the independent `attest` binary verifies (findings
+/// 2, 3): every Merkle leaf, plus the producer's claims. The attestor recomputes
+/// the root from these leaves and checks it against the claimed root, in a
+/// separate process that never reads the compliance report.
+fn write_evidence(dir: &Path, r: &CiResults) {
+    let ev = dir.join("evidence");
+    fs::create_dir_all(&ev).expect("create evidence dir");
+
+    let mut leaves = String::from("leaf\n");
+    for h in &r.merkle_leaves {
+        leaves.push_str(&format!("{:016x}\n", h.0));
+    }
+    fs::write(ev.join("leaves.tsv"), leaves).expect("write leaves");
+
+    let claims = format!(
+        "# evidence claims for independent attestation\n\
+         root\t{:016x}\n\
+         leaf_count\t{}\n\
+         total_comparisons\t{}\n\
+         reference_engine_id\t{:016x}\n\
+         rut_engine_id\t{:016x}\n\
+         engines_agree\t{}\n",
+        r.provenance.execution_merkle_root.0,
+        r.provenance.merkle_leaf_count,
+        r.provenance.total_comparisons,
+        r.provenance.reference_engine_id.0,
+        r.provenance.rut_engine_id.0,
+        r.provenance.engines_agree,
+    );
+    fs::write(ev.join("claims.tsv"), claims).expect("write claims");
+}
+
 fn build_reports(dir: &Path, r: &CiResults) {
     // 1. domain_participation_report
     write_report(
@@ -111,11 +143,27 @@ fn build_reports(dir: &Path, r: &CiResults) {
             ("altered_trace".into(), Json::Num(r.metamorphic.altered_trace)),
             ("altered_delta".into(), Json::Num(r.metamorphic.altered_delta)),
             ("altered_future".into(), Json::Num(r.metamorphic.altered_future)),
-            ("neutral_unexplained".into(), Json::Num(r.metamorphic.neutral_unexplained)),
+            ("consumed_perturbation_trace_violations".into(), Json::Num(r.metamorphic.expectation_violations)),
+            ("legitimately_neutral".into(), Json::Num(r.metamorphic.explained_neutral)),
+            ("consumed_perturbations".into(), Json::Int(r.metamorphic.consumed as i64)),
             ("failures".into(), fails(&r.metamorphic.failures)),
         ]),
     );
 
+    // 4b. causal_explanation_report (finding 10: intervention-confirmed edges)
+    write_report(
+        dir,
+        "causal_explanation_report",
+        &Json::Obj(vec![
+            ("pass".into(), pass_field(&r.causal_explanation.failures)),
+            ("edges_tested".into(), Json::Int(r.causal_explanation.edges_tested as i64)),
+            ("edges_confirmed".into(), Json::Int(r.causal_explanation.edges_confirmed as i64)),
+            ("confirmed_fraction".into(), Json::Num(r.causal_explanation.confirmed_fraction)),
+            ("method".into(), Json::s("ablate recorded causal source lane; require destination delta to change")),
+            ("failures".into(), fails(&r.causal_explanation.failures)),
+        ]),
+    );
+
     // 5. mutation_survivor_report
     let survivors: Vec<Json> = r
         .mutation
@@ -166,6 +214,9 @@ fn build_reports(dir: &Path, r: &CiResults) {
             ("total".into(), Json::Int(r.replay.total as i64)),
             ("deterministic".into(), Json::Int(r.replay.deterministic as i64)),
             ("drift".into(), Json::Int(r.replay.drift as i64)),
+            ("retained_failures_present".into(), Json::Bool(r.replay.retained_present)),
+            ("retained_failures_total".into(), Json::Int(r.replay.retained_total as i64)),
+            ("retained_failures_regressions".into(), Json::Int(r.replay.retained_regressions as i64)),
             ("failures".into(), fails(&r.replay.failures)),
         ]),
     );
@@ -226,9 +277,10 @@ fn build_reports(dir: &Path, r: &CiResults) {
 
 /// The reports the spec requires every CI run to produce. A missing or empty
 /// artifact is itself an acceptance failure (compliance rule 4).
-const REQUIRED_REPORTS: [&str; 9] = [
+const REQUIRED_REPORTS: [&str; 10] = [
     "domain_participation_report",
     "causal_rank_report",
+    "causal_explanation_report",
     "compression_resistance_report",
     "metamorphic_response_report",
     "mutation_survivor_report",
@@ -338,6 +390,13 @@ fn obligations(r: &CiResults) -> Vec<Obligation> {
             actual: 0,
             gate_pass: r.metamorphic.failures.is_empty(),
         },
+        Obligation {
+            requirement: "recorded causal edges are intervention-confirmed (not counted)",
+            artifact: "causal_explanation_report",
+            floor: 0,
+            actual: f(r.causal_explanation.edges_confirmed),
+            gate_pass: r.causal_explanation.failures.is_empty(),
+        },
         Obligation {
             requirement: "every admitted case satisfies its contract",
             artifact: "coverage_report",
@@ -555,6 +614,7 @@ fn main() {
     let elapsed = start.elapsed();
 
     build_reports(dir, &results);
+    write_evidence(dir, &results);
     write_markdown(dir, &results);
     let compliance_ok = build_compliance_report(dir, &results);
 

crates/generators/src/lib.rs

@@ -42,6 +42,10 @@ pub struct PerturbedCase {
     pub axis_name: String,
     pub world: WorldSnapshot,
     pub expectation: TraceDifferenceExpectation,
+    /// The domain this axis perturbs. The metamorphic gate uses this to enforce
+    /// the sound relation "a perturbation the program *consumes* must alter the
+    /// trace" rather than merely "some hash changed".
+    pub target_domain: usize,
 }
 
 /// A complete generated case (per spec).
@@ -156,6 +160,7 @@ pub fn generate_perturbations(world: &WorldSnapshot, seed: u64, count: usize) ->
             axis_name: axis.name(),
             world: axis.apply(world),
             expectation: axis.expected_trace_difference(),
+            target_domain: axis.target().0 as usize,
         });
     }
     out

crates/replay_corpus/Cargo.toml

@@ -10,6 +10,11 @@ rune_ir = { path = "../rune_ir" }
 trace_model = { path = "../trace_model" }
 generators = { path = "../generators" }
 reference_runtime = { path = "../reference_runtime" }
+runtime_under_test = { path = "../runtime_under_test" }
+
+[dev-dependencies]
+# Enables `buggy_resolve` for the retention negative-control test.
+runtime_under_test = { path = "../runtime_under_test", features = ["negative_controls"] }
 
 [lib]
 path = "src/lib.rs"

crates/replay_corpus/corpus/retained_failures.tsv

@@ -0,0 +1,7 @@
+# magicka-retained-failures v1
+seed	gate	note
+0000000000000001	runtime_equivalence	curated regression guard: independent-runtime equivalence on a causal-edge-bearing case (catches the dropped-edge bug class)
+0000000000000007	runtime_equivalence	curated regression guard: fault-heavy case (saturation/empty-accumulator paths)
+000000000000002a	runtime_equivalence	curated regression guard: temporal/future-dependence case
+00000000000000ff	runtime_equivalence	curated regression guard: high-coupling case
+0000000000000539	runtime_equivalence	curated regression guard: branch-divergence case

crates/replay_corpus/src/lib.rs

@@ -15,6 +15,8 @@ use reference_runtime::{execute, EngineConfig, ResolutionInput};
 use std::path::PathBuf;
 use world_model::Hash;
 
+pub mod retention;
+
 /// Format version of the persisted corpus file. Bump only with a deliberate,
 /// reviewed migration of the committed corpus.
 pub const CORPUS_VERSION: u32 = 1;
@@ -33,7 +35,7 @@ pub struct ReplayCase {
     pub expected_future_hash: Hash,
 }
 
-fn input_for(master_seed: u64) -> (ResolutionInput, u64, u64, u64, u64) {
+pub(crate) fn input_for(master_seed: u64) -> (ResolutionInput, u64, u64, u64, u64) {
     let (case, _accepted_seed) = generate_accepted_case(master_seed);
     let input = ResolutionInput {
         world: case.world.clone(),

crates/replay_corpus/src/retention.rs

@@ -0,0 +1,162 @@
+//! Failure retention (finding 6). A static seed corpus proves the engine is
+//! stable on a *fixed* sample; it does not retain *discovered* counterexamples.
+//! This module is the regression memory: every counterexample CI ever finds
+//! (e.g. a reference/runtime divergence) is curated into a committed,
+//! append-only file and **re-verified on every run**, so a fixed bug can never
+//! silently reappear.
+//!
+//! Two halves, both real:
+//! * The committed `corpus/retained_failures.tsv` is loaded and each case is
+//!   re-executed under the reference and the independent runtime-under-test; any
+//!   case where they disagree is a *regression* and fails CI.
+//! * When a run discovers a NEW divergence, it is serialized to the run's output
+//!   so it must be triaged and added to the committed set (the run also fails).
+//!   Discovered failures are therefore never lost.
+
+use crate::input_for;
+use reference_runtime::{canonical, execute, EngineConfig, ResolutionInput, ResolutionResult};
+use runtime_under_test::native_resolve;
+use std::path::PathBuf;
+
+/// A retained counterexample: the seed needed to regenerate it, the gate it
+/// originally tripped, and a human note.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct RetainedFailure {
+    pub master_seed: u64,
+    pub gate: String,
+    pub note: String,
+}
+
+/// Path to the committed retained-failures file.
+pub fn retained_path() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("corpus/retained_failures.tsv")
+}
+
+/// Serialize a retained set (with a provenance header).
+pub fn serialize(failures: &[RetainedFailure]) -> String {
+    let mut s = String::from("# magicka-retained-failures v1\n");
+    s.push_str("seed\tgate\tnote\n");
+    for f in failures {
+        // Tabs/newlines are stripped from free text to keep the TSV well-formed.
+        let gate = f.gate.replace(['\t', '\n'], " ");
+        let note = f.note.replace(['\t', '\n'], " ");
+        s.push_str(&format!("{:016x}\t{}\t{}\n", f.master_seed, gate, note));
+    }
+    s
+}
+
+/// Parse a retained set.
+pub fn parse(text: &str) -> Vec<RetainedFailure> {
+    let mut out = Vec::new();
+    for line in text.lines() {
+        if line.starts_with('#') || line.starts_with("seed") || line.trim().is_empty() {
+            continue;
+        }
+        let f: Vec<&str> = line.splitn(3, '\t').collect();
+        if f.len() < 1 {
+            continue;
+        }
+        if let Ok(seed) = u64::from_str_radix(f[0].trim(), 16) {
+            out.push(RetainedFailure {
+                master_seed: seed,
+                gate: f.get(1).unwrap_or(&"").to_string(),
+                note: f.get(2).unwrap_or(&"").to_string(),
+            });
+        }
+    }
+    out
+}
+
+/// Load the committed retained set. Missing file => empty set + `present=false`.
+pub fn load() -> (Vec<RetainedFailure>, bool) {
+    match std::fs::read_to_string(retained_path()) {
+        Ok(t) => (parse(&t), true),
+        Err(_) => (Vec::new(), false),
+    }
+}
+
+/// Append a newly-discovered failure to the committed set (append-only).
+pub fn append(failure: &RetainedFailure) -> std::io::Result<()> {
+    let (mut set, _present) = load();
+    if !set.iter().any(|f| f.master_seed == failure.master_seed) {
+        set.push(failure.clone());
+    }
+    let path = retained_path();
+    if let Some(parent) = path.parent() {
+        std::fs::create_dir_all(parent)?;
+    }
+    std::fs::write(&path, serialize(&set))
+}
+
+/// Does a retained case still agree between the reference and `resolve`? A
+/// retained counterexample is "fixed" iff the two implementations now produce
+/// identical canonical views on it.
+pub fn agrees(
+    failure: &RetainedFailure,
+    resolve: impl Fn(&ResolutionInput) -> ResolutionResult,
+) -> bool {
+    let (input, ..) = input_for(failure.master_seed);
+    canonical(&execute(&EngineConfig::reference(), &input)) == canonical(&resolve(&input))
+}
+
+/// Result of verifying the retained set.
+#[derive(Clone, Debug)]
+pub struct RetentionReport {
+    pub present: bool,
+    pub total: usize,
+    /// Seeds that regressed (reference and runtime-under-test disagree again).
+    pub regressions: Vec<u64>,
+}
+
+impl RetentionReport {
+    pub fn ok(&self) -> bool {
+        self.present && self.regressions.is_empty()
+    }
+}
+
+/// Verify the committed retained set against the independent runtime-under-test.
+pub fn verify() -> RetentionReport {
+    let (set, present) = load();
+    let regressions = set
+        .iter()
+        .filter(|f| !agrees(f, |inp| native_resolve(inp)))
+        .map(|f| f.master_seed)
+        .collect();
+    RetentionReport { present, total: set.len(), regressions }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use runtime_under_test::buggy_resolve;
+
+    #[test]
+    fn serialize_roundtrips() {
+        let set = vec![
+            RetainedFailure { master_seed: 0xABC, gate: "runtime_equivalence".into(), note: "dropped edge".into() },
+            RetainedFailure { master_seed: 0x1, gate: "replay".into(), note: "drift".into() },
+        ];
+        assert_eq!(parse(&serialize(&set)), set);
+    }
+
+    #[test]
+    fn committed_retained_set_exists_and_holds() {
+        // The committed file must be present (the retention mechanism is wired),
+        // and every retained counterexample must still be fixed.
+        let report = verify();
+        assert!(report.present, "committed retained_failures.tsv is missing");
+        assert!(report.regressions.is_empty(), "regressions: {:?}", report.regressions);
+    }
+
+    /// A retained counterexample re-checked against a *buggy* runtime must be
+    /// flagged as a regression. Proves the retention check is not vacuous: if a
+    /// fixed bug reappears, retention catches it.
+    #[test]
+    fn reintroduced_bug_is_caught_by_retention() {
+        let f = RetainedFailure { master_seed: 42, gate: "runtime_equivalence".into(), note: "synthetic".into() };
+        // Against the real runtime the case agrees (the bug is fixed)...
+        assert!(agrees(&f, |inp| native_resolve(inp)));
+        // ...but a runtime that reintroduces the bug is caught as a regression.
+        assert!(!agrees(&f, |inp| buggy_resolve(inp)));
+    }
+}