feat(review): wire the copycat containment engine into the gate

.loopover.yml.example

@@ -187,18 +187,19 @@ gate:
     # the gate. Bool. Default: false.
     aiAdvisory: false
 
-  # Copycat/plagiarism detection (#1969). CURRENTLY INERT — this config is parsed
-  # and threaded end-to-end, but the containment/similarity detection engine that
-  # would actually compute a copycat finding does not exist yet (tracked as
-  # separate, later PRs against #1969). Setting this today has no observable
-  # effect; it exists so an operator's config can already declare intent.
+  # Copycat/plagiarism detection (#1969): a deterministic code-containment check against prior art
+  # (earlier open or recently merged PRs on the same repo), direction resolved by submission
+  # timestamp so the earlier (original) author is never flagged.
   copycat:
     # off | warn | label | block. Default: off. A dedicated 4-tier scale (not the
-    # shared off/advisory/block used elsewhere) — a further "strikes" escalation
-    # beyond block reuses the existing cross-repo banned-contributors ledger.
+    # shared off/advisory/block used elsewhere): warn surfaces an advisory finding
+    # only; label also applies a label; block also closes the PR and counts toward
+    # a further "strikes" escalation that reuses the existing moderation-rules
+    # violation ledger (escalating to the global contributor blacklist at the
+    # configured ban threshold).
     mode: off
-    # Containment/similarity threshold at/above which mode acts, once the
-    # detection engine exists. Number 0–100, or null for the engine default.
+    # Containment/similarity threshold (0-100) at/above which mode acts.
+    # null uses the engine default (85).
     minScore: null
 
   # Oversized-PR gate. A PR at/above EITHER the file-count or line-count threshold

apps/loopover-ui/src/routes/docs.how-reviews-work.tsx

@@ -112,10 +112,11 @@ function HowReviewsWork() {
         </li>
         <li>
           <strong>Copycat / plagiarism gate</strong> (<code>copycatGateMode</code>, default{" "}
-          <code>off</code>) — a code containment/similarity check against prior art (repo history,
-          other PRs). Escalating tiers: <code>warn</code>, <code>label</code>, <code>block</code>,
-          plus a further strikes escalation for repeat offenders. Config only today — the detection
-          engine itself has not shipped yet, so setting this has no effect until it does.
+          <code>off</code>) — a code containment/similarity check against prior art (earlier open or
+          recently merged PRs on the same repo). Escalating tiers: <code>warn</code> surfaces an
+          advisory finding only; <code>label</code> also applies a label; <code>block</code> also
+          closes the PR and counts toward the repeat-offender strikes ledger. The direction is
+          always by submission timestamp, so the earlier (original) author is never flagged.
         </li>
         <li>
           <strong>Merge-readiness gate</strong> (<code>mergeReadinessGateMode</code>, default{" "}

apps/loopover-ui/src/routes/docs.tuning.tsx

@@ -336,11 +336,13 @@ function Tuning() {
           or the gate.
         </li>
         <li>
-          <code>gate.copycat.mode</code> — code containment/similarity gate against prior art (repo
-          history, other PRs). Default <code>off</code>. Escalating tiers: <code>warn</code>,{" "}
-          <code>label</code>, <code>block</code>, plus a further strikes escalation for repeat
-          offenders. Pair it with <code>gate.copycat.minScore</code> (0–100). Config only today —
-          the detection engine has not shipped yet, so this has no effect until it does.
+          <code>gate.copycat.mode</code> — code containment/similarity gate against prior art
+          (earlier open or recently merged PRs on the same repo). Default <code>off</code>.
+          Escalating tiers: <code>warn</code> surfaces an advisory finding only; <code>label</code>{" "}
+          also applies a label; <code>block</code> also closes the PR and counts toward the
+          repeat-offender strikes ledger. Pair it with <code>gate.copycat.minScore</code> (0–100;{" "}
+          <code>null</code> uses the engine default, <code>85</code>). Direction is always by
+          submission timestamp, so the earlier (original) author is never flagged.
         </li>
         <li>
           <code>gate.mergeReadiness</code> — composite merge-readiness gate. Default{" "}

config/examples/loopover.full.yml

@@ -201,18 +201,19 @@ gate:
     # the gate. Bool. Default: false.
     aiAdvisory: false
 
-  # Copycat/plagiarism detection (#1969). CURRENTLY INERT — this config is parsed
-  # and threaded end-to-end, but the containment/similarity detection engine that
-  # would actually compute a copycat finding does not exist yet (tracked as
-  # separate, later PRs against #1969). Setting this today has no observable
-  # effect; it exists so an operator's config can already declare intent.
+  # Copycat/plagiarism detection (#1969): a deterministic code-containment check against prior art
+  # (earlier open or recently merged PRs on the same repo), direction resolved by submission
+  # timestamp so the earlier (original) author is never flagged.
   copycat:
     # off | warn | label | block. Default: off. A dedicated 4-tier scale (not the
-    # shared off/advisory/block used elsewhere) — a further "strikes" escalation
-    # beyond block reuses the existing cross-repo banned-contributors ledger.
+    # shared off/advisory/block used elsewhere): warn surfaces an advisory finding
+    # only; label also applies a label; block also closes the PR and counts toward
+    # a further "strikes" escalation that reuses the existing moderation-rules
+    # violation ledger (escalating to the global contributor blacklist at the
+    # configured ban threshold).
     mode: off
-    # Containment/similarity threshold at/above which mode acts, once the
-    # detection engine exists. Number 0–100, or null for the engine default.
+    # Containment/similarity threshold (0-100) at/above which mode acts.
+    # null uses the engine default (85).
     minScore: null
 
   # Oversized-PR gate. A PR at/above EITHER the file-count or line-count threshold

migrations/0151_pull_request_copycat_assessment.sql

@@ -0,0 +1,5 @@
+-- Latest deterministic copycat/plagiarism containment assessment (#1969), persisted separately from the
+-- GitHub sync so a later maintenance pass (which re-reads the stored PR row rather than re-running the
+-- containment engine) can act on it -- mirrors slop_risk/slop_band (see the pull_requests table's own comment).
+ALTER TABLE pull_requests ADD COLUMN copycat_score INTEGER;
+ALTER TABLE pull_requests ADD COLUMN copycat_matched_pull_number INTEGER;

packages/loopover-engine/src/focus-manifest.ts

@@ -209,15 +209,14 @@ export type FocusManifestGateConfig = {
   /** `gate.copycat.mode` (#1969): off|warn|label|block, off by default. Config-as-code only -- no DB column
    *  or dashboard toggle. Deliberately a DEDICATED 4-value enum, not the shared `GateRuleMode` tri-state: the
    *  issue's tiered response is warn -> label -> block -> strikes, where "strikes" is a separate escalation
-   *  action (reusing the existing cross-repo banned-contributors ledger once wired) rather than a 5th mode
-   *  value. THIS FIELD IS CURRENTLY INERT -- the similarity/containment detection engine that would actually
-   *  compute a copycat finding does not exist yet (tracked as later, separate PRs against #1969); parsing and
-   *  threading this config end-to-end first proves the plumbing and lets an operator's `.loopover.yml`
-   *  already declare intent without waiting on the detection engine. */
+   *  action (reusing the existing moderation-rules violation ledger -- a `block`-tier close is tagged
+   *  `closeKind: "copycat"`, counted the same way as blacklist/contributor_cap/review_nag) rather than a 5th
+   *  mode value. Read by src/queue/copycat-detection.ts's deterministic containment engine, evaluated
+   *  alongside slop in src/queue/processors.ts. */
   copycatMode: CopycatGateMode | null;
   /** `gate.copycat.minScore` (#1969): containment/similarity score (0-100) at/above which `copycatMode` acts.
-   *  null (unset) ⇒ the (also currently inert) engine's own default threshold once it exists. Same 0-100
-   *  clamp-and-round normalization as `slopMinScore`/`readinessMinScore` above. */
+   *  null (unset) ⇒ the engine's own default threshold (85). Same 0-100 clamp-and-round normalization as
+   *  `slopMinScore`/`readinessMinScore` above. */
   copycatMinScore: number | null;
 };
 

packages/loopover-engine/src/settings/moderation-rules.ts

@@ -13,11 +13,14 @@
 
 /** The anti-abuse mechanisms this engine can count violations from -- the three ORIGINAL mechanisms
  *  (contributor cap, blacklist, review-nag) plus review-evasion (#review-evasion-protection: a contributor
- *  closing/converting-to-draft their own PR to dodge an active review). Kept as a closed union (not an open
+ *  closing/converting-to-draft their own PR to dodge an active review) and copycat/plagiarism containment
+ *  (#1969: the "strikes" tier of the copycat gate's own warn -> label -> block -> strikes response reuses
+ *  this SAME generic violation ledger rather than a bespoke counter -- a `block`-tier copycat close is tagged
+ *  `closeKind: "copycat"`, counted exactly like any other rule here). Kept as a closed union (not an open
  *  string) so an unrecognized value is always a normalization error, never silently accepted. */
-export type ModerationRuleType = "contributor_cap" | "blacklist" | "review_nag" | "review_evasion";
+export type ModerationRuleType = "contributor_cap" | "blacklist" | "review_nag" | "review_evasion" | "copycat";
 
-const ALL_MODERATION_RULE_TYPES: readonly ModerationRuleType[] = ["contributor_cap", "blacklist", "review_nag", "review_evasion"];
+const ALL_MODERATION_RULE_TYPES: readonly ModerationRuleType[] = ["contributor_cap", "blacklist", "review_nag", "review_evasion", "copycat"];
 
 /** The `audit_events.event_type` recorded for each rule's violation -- namespaced under `moderation.violation.*`
  *  so a cross-eventType, cross-repo count query (see `db/repositories.ts`) can scope to exactly this family. */
@@ -26,6 +29,7 @@ export const MODERATION_VIOLATION_EVENT_TYPE: Record<ModerationRuleType, string>
   blacklist: "moderation.violation.blacklist",
   review_nag: "moderation.violation.review_nag",
   review_evasion: "moderation.violation.review_evasion",
+  copycat: "moderation.violation.copycat",
 };
 
 export const DEFAULT_MODERATION_WARNING_LABEL = "mod:warning";