@@ -1122,6 +1122,26 @@ jobs:
           # the listener is released, so no false-positive leak
           [ "$(echo "$expr" | grep -cE '\[(OWN|EFF|DI)[0-9]{3}\]')" -eq 0 ] \
             || { echo "FAIL: a properly-released listener must not be reported"; exit 1; }
+      - name: Real-world cleanup patterns (OSS-benchmark FP fixes) are silent
+        run: |
+          python frontend/ownts/ownts.py frontend/ownts/examples/EffectRealWorld.tsx \
+            -o "$RUNNER_TEMP/rw.facts.json"
+          rw=$(python -m ownlang ownir "$RUNNER_TEMP/rw.facts.json")
+          echo "$rw"
+          # AbortController signal, ref/pre-declared timer handles, nested-block
+          # cleanup, observer.subscribe/unsubscribe — all released, zero findings.
+          [ "$(echo "$rw" | grep -cE '\[(OWN|EFF|DI)[0-9]{3}\]')" -eq 0 ] \
+            || { echo "FAIL: real-world cleanup patterns must not be reported"; exit 1; }
+      - name: False-negative controls (wrong controller / args / conditional cleanup) still leak
+        run: |
+          python frontend/ownts/ownts.py frontend/ownts/examples/EffectLeakControl.tsx \
+            -o "$RUNNER_TEMP/leak.facts.json"
+          leak=$(python -m ownlang ownir "$RUNNER_TEMP/leak.facts.json" || true)
+          echo "$leak"
+          # a release-shaped cleanup that does not release THIS resource must not be
+          # over-suppressed — all three controls stay OWN001
+          [ "$(echo "$leak" | grep -c 'OWN001')" -eq 3 ] \
+            || { echo "FAIL: broadened matchers must not over-suppress real leaks"; exit 1; }
       - name: The clean fixture (cleanups + useMemo'd dep) is silent
         run: |
           python frontend/ownts/ownts.py frontend/ownts/examples/DashboardClean.tsx \
 
@@ -0,0 +1,146 @@
+# OwnTS real-world benchmark — the false-positive reckoning
+
+A field note answering the gating question P-020 set for the OwnTS spike: *does it
+find real `useEffect` leaks in real OSS with low false positives?* Short answer for
+the first run: **no — 28/28 findings were false positives.** This note records the
+corpus, the result, and the prioritized false-positive (FP) catalog the run
+produced, plus what was done about it.
+
+## Method
+
+- **Corpus.** Real, published React hook libraries pulled from **npm** (the
+  session's egress policy blocks `github.com`, so a raw-source clone was not
+  possible; npm registry is allowed). Limited to packages whose published build is
+  **modern arrow-function ESM**, which the source-tuned spike parses as-is:
+  - `@mantine/hooks` 9.4.0
+  - `@react-hookz/web` 25.2.0
+  - `@uidotdev/usehooks` 2.4.1
+  - `usehooks-ts` 3.1.1
+- **Caveat.** `ahooks` and `react-use` were pulled too but ship **ES5
+  (`function(){}`) output**, which the spike (tuned for arrow `() =>` callbacks and
+  `return () =>` cleanups) does not parse — a separate parser-coverage gap, excluded
+  from the FP analysis rather than counted as analyzer FPs.
+- **Scale.** ~108 `useEffect` calls across 81 files.
+- **Run.** Each file → `ownts.extract` + `ownts.extract_effects` → `check_facts`;
+  findings collected and then **triaged by reading the actual source** around each.
+
+## Result (baseline — before this PR's fixes)
+
+| Code | Findings | True positive | False positive |
+|------|---------:|--------------:|---------------:|
+| `OWN001` | 28 | 0 | **28** |
+| `EFF001` | 0 | — | — |
+| **Total** | **28** | **0** | **28 (100%)** |
+
+Zero real leaks, zero effect storms, 28 false positives. These are well-maintained
+libraries that *do* clean up — just with patterns the synthetic-fixture-tuned spike
+did not model.
+
+## The FP catalog (what real code does that the spike missed)
+
+Ordered by frequency; each is a frontend (not core) limitation.
+
+1. **AbortController `{ signal }`** — listeners added with a `signal` option and torn
+   down by `controller.abort()` in cleanup (abort removes every signal-bound
+   listener at once). The spike had no model for it. *(mantine `use-floating-window`,
+   7 findings.)*
+2. **Handle stored in a ref / pre-declared `let`** — `timeoutRef.current =
+   setTimeout(...)`, `let i; … i = setInterval(...)`. `_lhs_token` only recognized a
+   same-statement `const/let/var NAME =`, so the handle was "uncapturable" and the
+   matching `clearTimeout(ref.current)` never matched. *(debounced-value, use-idle,
+   uidotdev, useVibrate.)*
+3. **Cleanup `return` from a nested block** — the `return () => …` lives inside an
+   `if` / `try` / `.then()` within the effect. `_cleanup_span` only accepted a return
+   at the effect body's own brace depth (1), so a depth-2 cleanup was invisible and
+   every resource read as un-released. *(use-media-query, use-scroller, useVibrate.)*
+4. **Aliased receiver** — `b.addEventListener(...)` in a `.then(b => …)` callback,
+   torn down by `battery.removeEventListener(...)` (same object, different
+   identifier). The full-key match compares the receiver string, so `b ≠ battery`.
+   *(uidotdev `useBattery`, 4 findings.)*
+5. **Cleanup via a named function or a method** — `return cancel`, `ro.unsubscribe`,
+   `resizeObserver.disconnect()`. The matcher could not follow a function reference
+   or a bare-statement subscribe. *(react-hookz `useResizeObserver`, debounced-value.)*
+6. **One-shot `setTimeout`** with no captured handle — fires once and is gone, not a
+   retained resource, but flagged like an un-cleared `setInterval`. *(use-focus-trap.)*
+
+## Verdict
+
+The spike was **not alpha-ready** on idiomatic modern hook code: ~100% FP. This is
+the honest "value, not form" check the consolidation note asked for. The catalog is
+the payoff — a concrete, prioritized list of what to model next, every item a small
+frontend extension.
+
+## What this PR changed (after)
+
+This PR teaches the **frontend** (not the core) to recognize the *provable* cleanup
+patterns — those where the teardown is visible in the effect — and leaves the
+genuinely-hard ones documented rather than guessed. Implemented:
+
+- **AbortController `{ signal }`** (#1): a signal-bound listener is released by a
+  `controller.abort()` in cleanup.
+- **Ref / pre-declared handle** (#2): `_lhs_token` now also recognizes
+  `ref.current = setTimeout(...)` and `let i; i = setInterval(...)`, so the matching
+  `clearTimeout(ref.current)` / `clearInterval(i)` lands.
+- **Nested-block cleanup** (#3): `_cleanup_span` switched from brace-depth to
+  **function-depth**, so a `return () => …` inside an `if`/`try`/`.then()` is the
+  effect's cleanup, while a `return` inside a nested callback still is not.
+- **Observer subscribe/unsubscribe** (part of #5): a bare `recv.subscribe(...)` is
+  released by `recv.unsubscribe(...)` / `recv.disconnect()` on the same receiver.
+
+Pinned by `frontend/ownts/examples/EffectRealWorld.tsx` (distilled from the OSS
+cases) + a CI step; `Dashboard`/`EffectEdges` still flag real leaks, proving the
+fixes do not over-suppress.
+
+### Result (after)
+
+| | Findings | Confirmed leaks | False positives |
+|---|---:|---:|---:|
+| **Baseline** | 28 | 0 | 28 |
+| **After** | **11** | 0 | 9 FP + 2 borderline |
+
+**17 false positives eliminated** (61%); correctly-silent effects rose from
+**80/108 → 97/108** specificity. Still zero confirmed leaks — these are
+well-maintained libraries, so that is the *expected* honest outcome, not a miss.
+
+### Residual (deliberately not fixed — they would require guessing)
+
+- **Aliased receiver** (#4): `b.addEventListener(...)` torn down by
+  `battery.removeEventListener(...)` (same object, different identifier). Needs alias
+  analysis. *(uidotdev `useBattery`, 4.)*
+- **Cross-effect / named-helper cleanup** (#5): the teardown is a `cancel()` /
+  `removeEventListeners()` helper, often called from a *different* effect. Following
+  it is interprocedural — out of scope for a narrow frontend. *(mantine
+  `use-debounced-value` 2, uidotdev `useScript` 2.)*
+- **One-shot `setTimeout`** (#6): an uncaptured `setTimeout` fires once and frees
+  itself; flagging it like a repeating `setInterval` is the conservative-but-noisy
+  call. Left as-is rather than silently suppressed (which could hide a real
+  re-render pileup). *(mantine `use-focus-trap`, 1.)*
+- **Borderline**: a listener intentionally left on a *cached* shared `<script>` node
+  (`usehooks-ts` `useScript`, 2) — defensible either way; the spike correctly
+  observes "never removed."
+
+The honest takeaway: OwnTS is now quiet on idiomatic cleanup, with its remaining
+false alarms confined to four named, understood patterns — a real step toward the
+"low false positives" bar P-020 set, without a single guessed release.
+
+### Reproduce
+
+```bash
+# (egress to npm only; github.com is blocked in this environment)
+# versions pinned to the exact builds benchmarked above, so reruns are reproducible
+npm pack @mantine/hooks@9.4.0 @react-hookz/web@25.2.0 \
+         @uidotdev/usehooks@2.4.1 usehooks-ts@3.1.1
+# extract each tarball, then run ownts.extract + extract_effects + check_facts
+# over every *.js/*.mjs (skip *.d.ts); triage each finding against the source.
+```
+
+### Soundness of the new matchers
+
+The broadened release matchers stay **fail-closed** — a release-shaped cleanup that
+does not actually release *this* resource still reports the leak, pinned by
+`EffectLeakControl.tsx`: a listener bound to `c1.signal` torn down by `c2.abort()`,
+a `ro.subscribe(a, h)` "released" by `ro.unsubscribe(b, h)`, and a cleanup returned
+only under `if (enabled)` over an unconditional `setInterval` — all three remain
+`OWN001`. The signal is tied to its controller, the observer to its argument list,
+and a conditional cleanup only releases acquires it dominates (co-guarded in the
+same block).
@@ -0,0 +1,33 @@
+// False-negative controls for the broadened release matchers (Codex/CodeRabbit):
+// each uses a release-shaped cleanup that does NOT actually release THIS resource,
+// so it must STILL report a leak. Run:
+//   python frontend/ownts/ownts.py frontend/ownts/examples/EffectLeakControl.tsx --check
+// Expect exactly three OWN001 findings.
+import { useEffect } from "react";
+
+export function LeakControl({ enabled }: { enabled: boolean }) {
+  // (1) wrong controller: the listener is bound to c1's signal, but cleanup aborts
+  // c2 — the original listener stays live.
+  useEffect(() => {
+    const c1 = new AbortController();
+    const c2 = new AbortController();
+    window.addEventListener("scroll", onScroll, { signal: c1.signal });
+    return () => c2.abort();
+  }, []);
+
+  // (2) mismatched unsubscribe args: subscribed with (a, h), torn down with (b, h)
+  // — the (a, h) subscription leaks.
+  useEffect(() => {
+    ro.subscribe(a, h);
+    return () => ro.unsubscribe(b, h);
+  }, []);
+
+  // (3) conditional cleanup: the timer is created unconditionally, but the cleanup
+  // is only returned when `enabled` — the !enabled path leaks.
+  useEffect(() => {
+    const id = setInterval(tick, 1000);
+    if (enabled) return () => clearInterval(id);
+  }, [enabled]);
+
+  return <div>leak control</div>;
+}
@@ -0,0 +1,51 @@
+// Real-world cleanup patterns the OSS benchmark (docs/notes/ownts-oss-benchmark.md)
+// found the spike was missing — each distilled to a minimal release that the
+// frontend must now recognise. Run:
+//   python frontend/ownts/ownts.py frontend/ownts/examples/EffectRealWorld.tsx --check
+// Expect ZERO findings — every resource here is properly released.
+// (The "still leaks" control lives in Dashboard.tsx / EffectEdges.tsx, so this
+// fixture also proves the fixes did not over-suppress real leaks.)
+import { useEffect, useRef } from "react";
+
+export function RealWorld({ src }: { src: string }) {
+  // AbortController: listeners bound to a signal, torn down by controller.abort().
+  useEffect(() => {
+    const controller = new AbortController();
+    const { signal } = controller;
+    window.addEventListener("mousemove", onMove, { signal });
+    window.addEventListener("mouseup", onEnd, { signal });
+    return () => controller.abort();
+  }, []);
+
+  // Timer handle stored in a ref, cleared inline in cleanup.
+  const timeoutRef = useRef(-1);
+  useEffect(() => {
+    timeoutRef.current = window.setTimeout(() => onReady(), 200);
+    return () => window.clearTimeout(timeoutRef.current);
+  }, []);
+
+  // Pre-declared `let` handle, assigned then cleared.
+  useEffect(() => {
+    let interval;
+    interval = setInterval(tick, 1000);
+    return () => clearInterval(interval);
+  }, []);
+
+  // Cleanup returned from a NESTED block (inside `if`) — still the effect's cleanup.
+  useEffect(() => {
+    if ("matchMedia" in window) {
+      const mq = window.matchMedia(src);
+      const cb = (e) => onMatch(e.matches);
+      mq.addEventListener("change", cb);
+      return () => mq.removeEventListener("change", cb);
+    }
+  }, [src]);
+
+  // Bare observer.subscribe(...) released by observer.unsubscribe(...) on the same receiver.
+  useEffect(() => {
+    ro.subscribe(target, handler);
+    return () => ro.unsubscribe(target, handler);
+  }, []);
+
+  return <div>real world</div>;
+}