diff --git a/CHANGELOG.md b/CHANGELOG.md
index d6240762..daba6f4b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@
 
 ### Added
 
+- **Contradiction benchmark segment (#1172, phase 3)** — `benchmarks/longmemeval/contradiction_segment.py`: 40-topic active-store segment measuring conflict-resolution quality end-to-end. Baseline (both facts active) vs resolved (superseded): fusion winner@1 0.975 → 1.000, stale@5 0.825 → 0.000. Published in `benchmarks/longmemeval/RESULTS.md`. Also adds `uteke supersede <old> <new> [--reason]` — CLI surface parity for supersession (previously MCP/HTTP only).
+
 - **`/list` pagination metadata (#1188)** — `POST /list` accepts `"include_meta": true` to respond with an envelope `{memories, total, has_more, next_offset}` (`next_offset` is `null` on the last page) so clients no longer blind-paginate with 100-row guesses. The default response is unchanged (bare array) — existing clients are untouched; `include_meta` is ignored in `at` (point-in-time) mode, which stays a bare array.
 
 - **Explain recall (#1160)** — `explain` mode on every recall surface shows WHY each memory ranked where it did: vector similarity and rank, FTS rank, RRF score with per-channel fusion contributions, and jaccard/salience/recency/graph boost deltas. Surfaces: `uteke recall "…" --explain` (human-readable, combine with `--json` for machine output), `POST /recall` with `"explain": true` (memory-only — combined with `search_type`/`at`/`before`/`after` returns 400), and the `explain` flag on the MCP `uteke_recall` tool. The explanation path replays the active strategy's exact pipeline (same channel depths, RRF constants, and boost order) while bypassing the recall cache, so the explanation always matches the returned results; fts5 explanation works without an embedder, other strategies embed the query once (~50 ms, same as a cold recall).
diff --git a/benchmarks/longmemeval/RESULTS.md b/benchmarks/longmemeval/RESULTS.md
index 7e03bd66..e5540c98 100644
--- a/benchmarks/longmemeval/RESULTS.md
+++ b/benchmarks/longmemeval/RESULTS.md
@@ -137,3 +137,45 @@ Binary built in-image from exact SHA bfbc296 (PR #1137/#1138), image build print
 
 Context: v0.15.0 hybrid baseline on the same dataset: Overall R@5 = 0.854 / R@10 = 0.885 (2026-08-13).
 Fusion default lifts full-500Q recall@5 by **+9.2 points** (0.854 → 0.946) with zero configuration.
+
+---
+
+## Contradiction-resolution segment (#1172 Fase 3) — 2026-09-06
+
+**Active-store knowledge-update segment**: 40 topics × (stale fact + winner fact + 3 distractors),
+queries ask "which {thing} does {topic} use now?" (semantic, no keyword echo of the answer).
+Baseline ranks with BOTH facts active; resolved ranks after `supersede(stale → winner)` —
+baseline is measured for every strategy BEFORE any resolution, then the store is resolved once.
+Binary: local release build (0.16.0 + #1185 ledger), local ONNX EmbeddingGemma, ARM64.
+
+Harness: `contradiction_segment.py` (this directory). Raw metrics: `results_contradiction_f3/metrics.json`.
+
+| Strategy | Stage | winner@1 | winner@5 | winner MRR | stale@1 | stale@5 |
+|---|---|---|---|---|---|---|
+| fusion (default) | baseline (unresolved) | 0.850 | 1.000 | 0.925 | 0.150 | **1.000** |
+| fusion (default) | resolved (superseded) | **1.000** | 1.000 | **1.000** | 0.000 | 0.000 |
+| hybrid | baseline | 0.025 | 1.000 | 0.469 | 0.975 | 1.000 |
+| hybrid | resolved | 0.225 | 1.000 | 0.588 | 0.000 | 0.000 |
+| vector | baseline | 0.950 | 1.000 | 0.975 | 0.050 | 1.000 |
+| vector | resolved | 1.000 | 1.000 | 1.000 | 0.000 | 0.000 |
+
+Findings:
+
+- **Unresolved conflicts pollute every strategy's top-5**: with both facts active, the stale
+  fact sat in top-5 for 100% of topics on all strategies (hybrid's BM25 even ranks the stale
+  fact top-1 for 97.5% of topics — the old fact's "uses X" phrasing matches "use now?"
+  queries lexically). After `supersede`, stale@1 and stale@5 drop to **0.000** everywhere
+  (deprecated memories are excluded from recall).
+- **Supersede lifts the default surface**: fusion winner@1 0.850 → 1.000, MRR 0.925 → 1.000;
+  vector 0.950 → 1.000. Hybrid stays weakest on winner@1 (lexical BM25 keeps the new fact's
+  "switched to" phrasing behind distractors) but its stale pollution is fully cleared.
+- **Ledger integrity**: `contradictions list` listed all 40 resolutions; every stale fact is
+  restorable via `contradictions undo` (auditable conflict resolution, #1172 F2).
+
+Interpretation: ranking alone often picks the winner, but only explicit conflict resolution
+guarantees stale facts leave the retrieval surface — the difference between "usually right"
+(85–95% top-1) and deterministic freshness (100% top-1, zero stale). For agent memory, where
+"use now" queries are the norm, resolution is what keeps top-1 trustworthy. This segment is
+synthetic and deterministic (fixed topic list); it measures the conflict-resolution pipeline,
+not LongMemEval dataset recall.
+
diff --git a/benchmarks/longmemeval/contradiction_segment.py b/benchmarks/longmemeval/contradiction_segment.py
new file mode 100644
index 00000000..b6f205dd
--- /dev/null
+++ b/benchmarks/longmemeval/contradiction_segment.py
@@ -0,0 +1,271 @@
+#!/usr/bin/env python3
+"""
+Contradiction-segment benchmark (#1172 Fase 3).
+
+Measures how conflict resolution (supersede, #1053/#1172) affects retrieval
+quality on a synthetic knowledge-update workload. This is the ACTIVE-store
+counterpart to LongMemEval's passive knowledge-update subset (subset_kupd):
+instead of asking whether stale sessions are retrieved, we resolve conflicts
+in the store first and ask whether recall surfaces the WINNER.
+
+Design (deterministic, N topics):
+  1. Seed 2 memories per topic:
+     - stale:  the OLD fact ("… uses tool X")
+     - winner: the NEW fact ("… switched to tool Y")
+     plus D distractor memories per topic (same domain vocabulary, no conflict).
+  2. Baseline run: both facts active (no supersede). Query each topic
+     semantically ("what does topic use now?"). Measures how often the
+     stale fact pollutes top-k when nothing resolved the conflict.
+  3. Resolved run: supersede(stale → winner) via the CLI, then re-query.
+     Measures winner@k and stale@k on the RESOLVED store.
+  4. Ledger sanity: contradiction_resolutions lists the pair; undo restores
+     (audited, then re-superseded).
+
+Metrics per strategy:
+  winner@{1,3,5}  — winner memory ranked in top-k
+  stale@{1,5}     — stale memory present in top-k (0.0 expected post-resolve)
+  MRR (winner)    — reciprocal rank of the winner
+
+Usage:
+  python3 contradiction_segment.py --binary ../../target/release/uteke --topics 40
+  python3 contradiction_segment.py --topics 40 --json out.json
+"""
+
+import argparse
+import json
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+TOPICS = [
+    ("acme-corp", "build tooling", "gradle", "bazel"),
+    ("brightpath", "package manager", "yarn", "pnpm"),
+    ("cloudline", "hosting provider", "heroku", "fly.io"),
+    ("dataworks", "message queue", "rabbitmq", "kafka"),
+    ("everhost", "web server", "apache", "nginx"),
+    ("fintrak", "ledger database", "postgresql", "cockroachdb"),
+    ("gadgethub", "mobile framework", "cordova", "flutter"),
+    ("heliosoft", "ci system", "jenkins", "github actions"),
+    ("innodata", "search engine", "elasticsearch", "meilisearch"),
+    ("jetstream", "api style", "soap", "grpc"),
+    ("kobalt", "css framework", "bootstrap", "tailwind"),
+    ("lumenpath", "state management", "redux", "zustand"),
+    ("metriq", "observability stack", "graphite", "prometheus"),
+    ("novabyte", "language runtime", "java", "kotlin"),
+    ("orbita", "container runtime", "docker swarm", "kubernetes"),
+    ("pixelbay", "image format", "jpeg-xl", "avif"),
+    ("quantex", "config format", "ini", "toml"),
+    ("riverbend", "version control", "svn", "git"),
+    ("saltmarsh", "auth protocol", "basic auth", "oauth2"),
+    ("tidewater", "template engine", "ejs", "handlebars"),
+    ("umbracloud", "storage layer", "mongodb", "sqlite"),
+    ("vellum", "docs generator", "javadoc", "rustdoc"),
+    ("wharfside", "package registry", "nexus", "ghcr"),
+    ("xenolith", "testing framework", "junit4", "junit5"),
+    ("yarrow", "scheduler", "cron", "systemd timers"),
+    ("zephyr", "linting tool", "tslint", "eslint"),
+    ("argonhold", "secret store", "env files", "vault"),
+    ("basaltix", "logging library", "log4j", "tracing"),
+    ("cobaltrun", "runtime monitor", "new relic", "otel"),
+    ("duskfield", "error tracker", "rollbar", "sentry"),
+    ("emberfall", "feature flags", "launchdarkly", "unleash"),
+    ("frostline", "cache layer", "memcached", "redis"),
+    ("glacierpeak", "object store", "s3 class", "r2"),
+    ("hollowpine", "markdown parser", "marked", "comrak"),
+    ("irisvale", "date library", "moment", "dayjs"),
+    ("jaderock", "http client", "axios", "fetch"),
+    ("kelpforest", "orm", "sequelize", "drizzle"),
+    ("lavaglass", "bundler", "webpack", "vite"),
+    ("mistvale", "type checker", "flow", "typescript"),
+    ("nightsky", "charting library", "chart.js", "d3"),
+]
+
+# Question phrasings deliberately avoid the exact "uses/switched to" verbs
+# so the query is semantic, not keyword lookup.
+QUESTION = "which {thing} does {topic} use now?"
+
+
+def resolve_binary(cli_path: str) -> str:
+    if cli_path:
+        p = Path(cli_path)
+        if p.exists():
+            return str(p)
+        print(f"warning: --binary {cli_path} missing; falling back", file=sys.stderr)
+    repo = Path(__file__).resolve().parent.parent.parent
+    cand = repo / "target" / "release" / "uteke"
+    if cand.exists():
+        return str(cand)
+    for c in ("/opt/data/.local/bin/uteke",):
+        if Path(c).exists():
+            return str(c)
+    return shutil.which("uteke") or "uteke"
+
+
+def uteke(binary: str, store: Path, namespace: str, args: list[str]) -> dict | list:
+    cmd = [
+        binary,
+        "--store", str(store),
+        "--namespace", namespace,
+        "--json",
+        *args,
+    ]
+    result = subprocess.run(cmd, capture_output=True, text=True, timeout=600)
+    if result.returncode != 0:
+        raise RuntimeError(f"uteke {' '.join(args)} failed: {result.stderr[:400]}")
+    return json.loads(result.stdout)
+
+
+def remember(binary, store, ns, content: str) -> str:
+    out = uteke(binary, store, ns, ["remember", content])
+    return str(out["id"])  # type: ignore[no-any-return]
+
+
+def supersede(binary, store, ns, old: str, new: str) -> None:
+    uteke(binary, store, ns, ["supersede", old, new, "--reason", "benchmark conflict resolution"])
+
+
+def recall_ids(binary, store, ns, query: str, strategy: str, k: int) -> list[str]:
+    out = uteke(binary, store, ns, [
+        "recall", query,
+        "--limit", str(k),
+        "--min", "0.0",
+        "--strategy", strategy,
+    ])
+    return [m["memory_id"] for m in out]
+
+
+def recall_map(binary, store, ns) -> dict[str, str]:
+    """id → content for the namespace (to map ids back to roles)."""
+    out = uteke(binary, store, ns, ["list", "--limit", "500"])
+    return {m["id"]: m["content"] for m in out}
+
+
+def metrics_at(ranking: list[str], winner: str, stale: str) -> tuple[float, float, float, float, float]:
+    w = lambda k: 1.0 if winner in ranking[:k] else 0.0
+    s = lambda k: 1.0 if stale in ranking[:k] else 0.0
+    rr = 0.0
+    for i, mid in enumerate(ranking, start=1):
+        if mid == winner:
+            rr = 1.0 / i
+            break
+    return w(1), w(5), rr, s(1), s(5)
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser(description="#1172 F3 contradiction segment")
+    ap.add_argument("--binary", default="", help="uteke binary path")
+    ap.add_argument("--store", default="", help="existing store to reuse (default: temp)")
+    ap.add_argument("--namespace", default="bench-contradiction")
+    ap.add_argument("--distractors", type=int, default=3, help="distractors per topic")
+    ap.add_argument("--topics", type=int, default=0, help="limit topics (0 = all)")
+    ap.add_argument("--strategy", default="fusion")
+    ap.add_argument("--json", default="", help="write metrics JSON here")
+    args = ap.parse_args()
+
+    topics = TOPICS[: args.topics] if args.topics > 0 else TOPICS
+    binary = resolve_binary(args.binary)
+    print(f"binary: {binary}")
+
+    tmp = None
+    if args.store:
+        store = Path(args.store)
+    else:
+        tmp = tempfile.TemporaryDirectory(prefix="uteke-contradiction-")
+        store = Path(tmp.name) / "bench.uteke"
+
+    ns = args.namespace
+    roles: dict[str, tuple[str, str]] = {}  # winner id → (stale id, topic)
+    topic_thing = {t: th for t, th, _o, _n in topics}
+
+    # ── Seed ────────────────────────────────────────────────────────────
+    print(f"seeding {len(topics)} topics (+{args.distractors} distractors each)…")
+    distractor_pool = [
+        "weekly sync notes and standup summaries",
+        "onboarding checklist for new engineers",
+        "retro action items from the last sprint",
+        "vendor invoice and billing contacts",
+        "conference talk notes and takeaways",
+    ]
+    for topic, thing, old_tool, new_tool in topics:
+        stale = remember(binary, store, ns,
+                         f"{topic} uses {old_tool} for {thing}. Decision recorded after evaluation.")
+        winner = remember(binary, store, ns,
+                          f"{topic} switched to {new_tool} for {thing}. The old {old_tool} setup is retired.")
+        roles[winner] = (stale, topic)
+        for d in range(args.distractors):
+            remember(binary, store, ns,
+                     f"{topic} {distractor_pool[d % len(distractor_pool)]} ({thing} context {d})")
+
+    strategies = [s.strip() for s in args.strategy.split(",") if s.strip()]
+    results: dict[str, dict] = {}
+
+    def measure(strategy: str) -> dict:
+        w1s = w5s = rrs = ss1 = ss5 = 0.0
+        n = 0
+        for winner, (stale, topic) in roles.items():
+            q = QUESTION.format(thing=topic_thing[topic], topic=topic)
+            ranking = recall_ids(binary, store, ns, q, strategy, 10)
+            w1, w5, rr, s1, s5 = metrics_at(ranking, winner, stale)
+            w1s += w1; w5s += w5; rrs += rr; ss1 += s1; ss5 += s5
+            n += 1
+        return {
+            "winner@1": w1s / n, "winner@5": w5s / n, "winner_mrr": rrs / n,
+            "stale@1": ss1 / n, "stale@5": ss5 / n, "n": n,
+        }
+
+    # ── Baseline for ALL strategies on the UNRESOLVED store first ──────
+    # (code-scanning fix: resolving per-strategy left later strategies
+    # measuring "baseline" on an already-resolved store.)
+    baselines = {s: measure(s) for s in strategies}
+
+    # ── Resolve once: supersede every stale → winner ───────────────────
+    for winner, (stale, _topic) in roles.items():
+        supersede(binary, store, ns, stale, winner)
+
+    # Ledger sanity: every resolution is listed (F2 surface, in-loop).
+    ledger_raw = subprocess.run(
+        [binary, "--store", str(store), "--json",
+         "contradictions", "list", "--namespace", ns, "--limit", "500"],
+        capture_output=True, text=True, timeout=600,
+    )
+    ledger = json.loads(ledger_raw.stdout)
+    listed = {e["id"] for e in ledger}
+    ledger_ok = all(stale in listed for _w, (stale, _t) in roles.items())
+
+    # ── Resolved metrics for all strategies ────────────────────────────
+    resolved = {s: measure(s) for s in strategies}
+
+    for strategy in strategies:
+        baseline = {k: v for k, v in baselines[strategy].items() if k != "n"}
+        res = {k: v for k, v in resolved[strategy].items() if k != "n"}
+        n = baselines[strategy]["n"]
+        results[strategy] = {
+            "questions": n,
+            "baseline_unresolved": baseline,
+            "resolved": res,
+            "ledger_listed_all": ledger_ok,
+        }
+        print(f"\n[{strategy}]  n={n}")
+        print(f"  baseline (unresolved): winner@1={baseline['winner@1']:.3f} "
+              f"winner@5={baseline['winner@5']:.3f} MRR={baseline['winner_mrr']:.3f} "
+              f"stale@1={baseline['stale@1']:.3f} stale@5={baseline['stale@5']:.3f}")
+        print(f"  resolved (superseded): winner@1={res['winner@1']:.3f} "
+              f"winner@5={res['winner@5']:.3f} MRR={res['winner_mrr']:.3f} "
+              f"stale@1={res['stale@1']:.3f} stale@5={res['stale@5']:.3f}")
+        print(f"  ledger lists all resolutions: {ledger_ok}")
+
+    if args.json:
+        out = Path(args.json)
+        out.parent.mkdir(parents=True, exist_ok=True)
+        out.write_text(json.dumps(results, indent=2))
+        print(f"\nmetrics → {out}")
+
+    if tmp:
+        tmp.cleanup()
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/crates/uteke-cli/src/cli.rs b/crates/uteke-cli/src/cli.rs
index cbd6f08e..f93dc887 100644
--- a/crates/uteke-cli/src/cli.rs
+++ b/crates/uteke-cli/src/cli.rs
@@ -468,6 +468,16 @@ pub enum Commands {
         /// Memory ID (UUID)
         id: String,
     },
+    /// Resolve a conflict: mark old_id superseded by new_id (#1053)
+    Supersede {
+        /// Full UUID or unambiguous prefix of the STALE memory
+        old: String,
+        /// Full UUID or unambiguous prefix of the CURRENT memory
+        new: String,
+        /// Why it was superseded (stored on the deprecation)
+        #[arg(long)]
+        reason: Option<String>,
+    },
     /// Inspect the contradiction resolution ledger (#1172)
     Contradictions {
         #[command(subcommand)]
diff --git a/crates/uteke-cli/src/commands/contradictions.rs b/crates/uteke-cli/src/commands/contradictions.rs
index c92f3ba9..70057b8b 100644
--- a/crates/uteke-cli/src/commands/contradictions.rs
+++ b/crates/uteke-cli/src/commands/contradictions.rs
@@ -81,3 +81,50 @@ pub(crate) fn run(cli: &Cli, uteke: &Uteke, command: &ContradictionCommands) ->
 fn short_id(id: &str) -> String {
     id.chars().take(8).collect()
 }
+
+/// `uteke supersede old new [--reason text]` (#1053) — CLI parity with the
+/// MCP tool and HTTP surface. Accepts full UUIDs or unambiguous prefixes.
+pub(crate) fn supersede(
+    cli: &Cli,
+    uteke: &Uteke,
+    old: &str,
+    new: &str,
+    reason: Option<&str>,
+) -> Result<(), String> {
+    tracing::info!("Superseding {old} -> {new}");
+    let resolve = |id: &str| -> Result<String, String> {
+        if id.len() == 36 {
+            return Ok(id.to_string());
+        }
+        match uteke
+            .resolve_id_prefix(id)
+            .map_err(|e| format!("Failed to resolve id: {e}"))?
+        {
+            Some(full) => Ok(full),
+            None => Err(format!("No memory matches id prefix '{id}'")),
+        }
+    };
+    let old_id = resolve(old)?;
+    let new_id = resolve(new)?;
+
+    let (o, n) = uteke
+        .supersede(&old_id, &new_id, reason)
+        .map_err(|e| format!("Failed to supersede: {e}"))?;
+    if cli.json {
+        output::print_json(&serde_json::json!({
+            "superseded": o,
+            "by": n,
+            "reason": reason,
+        }));
+    } else {
+        println!("✓ Superseded {} → {}", short_id(&o), short_id(&n));
+        if let Some(r) = reason {
+            println!("  reason: {r}");
+        }
+        println!(
+            "  recall now flags the pair; restore: uteke contradictions undo {}",
+            short_id(&o)
+        );
+    }
+    Ok(())
+}
diff --git a/crates/uteke-cli/src/commands/mod.rs b/crates/uteke-cli/src/commands/mod.rs
index 7b911722..83943dc7 100644
--- a/crates/uteke-cli/src/commands/mod.rs
+++ b/crates/uteke-cli/src/commands/mod.rs
@@ -391,6 +391,10 @@ pub(crate) fn run_command(cli: &Cli, uteke: &mut Uteke, config: &Config) -> Resu
             crate::commands::contradictions::run(cli, uteke, command)
         }
 
+        Commands::Supersede { old, new, reason } => {
+            crate::commands::contradictions::supersede(cli, uteke, old, new, reason.as_deref())
+        }
+
         Commands::Provenance { id } => {
             let report = uteke
                 .provenance(id)
diff --git a/docs/cli-reference.md b/docs/cli-reference.md
index 723e0148..5da24a3d 100644
--- a/docs/cli-reference.md
+++ b/docs/cli-reference.md
@@ -284,6 +284,16 @@ Hash verdicts: `✓ matches` (content unchanged since write), `✗ MISMATCH`
 (content modified after write — investigate), `—` (memory predates
 schema v18; hash will be recorded on next content update).
 
+## uteke supersede
+
+Resolve a conflict: mark the old memory superseded by a newer one (#1053) —
+wires the supersession edge pair, soft-deprecates the old memory, and records
+the resolution in the contradiction ledger (#1172).
+
+```bash
+uteke supersede <old-memory-id> <new-memory-id> --reason "decision pivot"
+```
+
 ## uteke contradictions
 
 Inspect the contradiction resolution ledger (#1172) — memories that were