diff --git a/gitnexus/src/core/group/cross-impact.ts b/gitnexus/src/core/group/cross-impact.ts
index f8625cdc5..eab942a62 100644
--- a/gitnexus/src/core/group/cross-impact.ts
+++ b/gitnexus/src/core/group/cross-impact.ts
@@ -91,6 +91,25 @@ function clampCrossDepth(raw: unknown): { depth: number; warning?: string } {
   return { depth: d };
 }
 
+/**
+ * Clamp the impact timeout to a sane bounded range. Callers can feed this
+ * via tool params, so an unclamped value lets a single request hold a
+ * timer slot for an arbitrarily long duration (CodeQL js/resource-
+ * exhaustion). 100ms lower bound preserves test-suite scenarios that
+ * exercise tight timeouts; 5min upper bound is well above any legitimate
+ * single-impact compute. Applied at the validate boundary so the
+ * downstream `deadline` (Date.now() + timeoutMs) and the local-leg
+ * `setTimeout` see the same clamped value — earlier shapes had a 1hr
+ * outer cap and a 5min inner clamp that disagreed.
+ */
+export const IMPACT_TIMEOUT_MIN_MS = 100;
+export const IMPACT_TIMEOUT_MAX_MS = 5 * 60 * 1_000;
+
+export function clampTimeout(timeoutMs: number): number {
+  if (!Number.isFinite(timeoutMs) || timeoutMs <= 0) return IMPACT_TIMEOUT_MIN_MS;
+  return Math.min(IMPACT_TIMEOUT_MAX_MS, Math.max(IMPACT_TIMEOUT_MIN_MS, Math.trunc(timeoutMs)));
+}
+
 export function validateGroupImpactParams(params: Record<string, unknown>):
   | {
       ok: true;
@@ -143,13 +162,19 @@ export function validateGroupImpactParams(params: Record<string, unknown>):
   const service = normalizeServicePrefix(params.service);
   const subgroup = typeof params.subgroup === 'string' ? params.subgroup : undefined;
 
-  let timeoutMs =
+  // Clamp at the validate boundary so the downstream `deadline` (line
+  // ~366) and `safeLocalImpact`'s `setTimeout` both see a single
+  // bounded value. Without this, the outer deadline budgeted Phase-2
+  // cross-repo fanout up to 1hr while only the inner setTimeout was
+  // capped to 5min — the two halves of CodeQL #184's mitigation
+  // disagreed.
+  const rawTimeoutMs =
     typeof params.timeoutMs === 'number' && params.timeoutMs > 0
       ? params.timeoutMs
       : typeof params.timeout === 'number' && params.timeout > 0
         ? params.timeout
         : DEFAULT_LOCAL_IMPACT_TIMEOUT_MS;
-  if (timeoutMs > 3_600_000) timeoutMs = 3_600_000;
+  const timeoutMs = clampTimeout(rawTimeoutMs);
 
   return {
     ok: true,
@@ -191,12 +216,13 @@ async function safeLocalImpact(
   impactParams: Parameters<GroupToolPort['impact']>[1],
   timeoutMs: number,
 ): Promise<{ value: unknown; timedOut: boolean }> {
+  const safeTimeoutMs = clampTimeout(timeoutMs);
   let timer: ReturnType<typeof setTimeout> | undefined;
   const impactP = port.impact(repo, impactParams).catch((err) => ({
     error: err instanceof Error ? err.message : String(err),
   }));
   const timeoutP = new Promise<'timeout'>((resolve) => {
-    timer = setTimeout(() => resolve('timeout'), timeoutMs);
+    timer = setTimeout(() => resolve('timeout'), safeTimeoutMs);
   });
   const won = await Promise.race([
     impactP.then((v) => ({ tag: 'impact' as const, v })),
@@ -212,6 +238,65 @@ async function safeLocalImpact(
   return { value: won.v, timedOut: false };
 }
 
+/**
+ * Race a single Phase-2 `impactByUid` call against a remaining-budget
+ * timer. The Codex adversarial review on PR #1331 surfaced that the
+ * fanout loop only checked `Date.now() > deadline` *between* neighbor
+ * calls — once `await port.impactByUid(...)` was reached, a hung
+ * neighbor could pin the request indefinitely, and slow neighbors
+ * could compound past the 5-min `IMPACT_TIMEOUT_MAX_MS` cap.
+ *
+ * This helper wraps each call: a `setTimeout(remainingMs)` aborts an
+ * `AbortController` whose signal is forwarded to `impactByUid`, and a
+ * `Promise.race` resolves to `{ timedOut: true }` when the timer
+ * fires before the call completes. Implementors that ignore the
+ * signal (current local backend) still see their await resolved by
+ * the race; full cooperative cancellation inside the BFS is a future
+ * follow-up. On rejection, the value is `null` (matching the
+ * fanout's existing `if (fan == null)` truncation contract).
+ *
+ * Exported for direct unit testing — the helper IS the load-bearing
+ * mitigation surface, so the U3 regression test pins it directly
+ * rather than driving the full `runGroupImpact` path.
+ */
+export async function safeNeighborImpact(
+  port: GroupToolPort,
+  repoId: string,
+  uid: string,
+  direction: string,
+  opts: {
+    maxDepth: number;
+    relationTypes: string[];
+    minConfidence: number;
+    includeTests: boolean;
+  },
+  remainingMs: number,
+): Promise<{ value: unknown; timedOut: boolean }> {
+  const controller = new AbortController();
+  let timer: ReturnType<typeof setTimeout> | undefined;
+  const callP = port
+    .impactByUid(repoId, uid, direction, { ...opts, signal: controller.signal })
+    .catch(() => null);
+  const timeoutP = new Promise<'timeout'>((resolve) => {
+    timer = setTimeout(
+      () => {
+        controller.abort();
+        resolve('timeout');
+      },
+      Math.max(0, remainingMs),
+    );
+  });
+  const won = await Promise.race([
+    callP.then((v) => ({ tag: 'impact' as const, v })),
+    timeoutP.then(() => ({ tag: 'timeout' as const })),
+  ]);
+  if (timer !== undefined) clearTimeout(timer);
+  if (won.tag === 'timeout') {
+    return { value: null, timedOut: true };
+  }
+  return { value: won.v, timedOut: false };
+}
+
 export function collectImpactSymbolUids(
   local: unknown,
   servicePrefix: string | undefined,
@@ -476,7 +561,8 @@ export async function runGroupImpact(
       if (seen.has(key)) continue;
       seen.add(key);
 
-      if (Date.now() > deadline) {
+      const remainingMs = deadline - Date.now();
+      if (remainingMs <= 0) {
         truncatedRepos.push(n.neighborRepo);
         continue;
       }
@@ -492,13 +578,25 @@ export async function runGroupImpact(
         continue;
       }
 
-      const fan = await deps.port.impactByUid(neighborHandle.id, n.neighborUid, direction, {
-        maxDepth,
-        relationTypes: relationTypes ?? [],
-        minConfidence,
-        includeTests,
-      });
-      if (fan == null) {
+      // Phase-2 hardening: race each impactByUid against a per-call
+      // timeout derived from the remaining budget. Without this wrap a
+      // single hung neighbor would pin the request past the clamped
+      // timeout, which Codex's adversarial review on PR #1331 flagged
+      // as the still-open half of CodeQL #184 / js/resource-exhaustion.
+      const { value: fan, timedOut: neighborTimedOut } = await safeNeighborImpact(
+        deps.port,
+        neighborHandle.id,
+        n.neighborUid,
+        direction,
+        {
+          maxDepth,
+          relationTypes: relationTypes ?? [],
+          minConfidence,
+          includeTests,
+        },
+        remainingMs,
+      );
+      if (neighborTimedOut || fan == null) {
         truncatedRepos.push(n.neighborRepo);
         continue;
       }
diff --git a/gitnexus/src/core/group/extractors/rust-workspace-extractor.ts b/gitnexus/src/core/group/extractors/rust-workspace-extractor.ts
index 63fe7ea82..d58c3e08f 100644
--- a/gitnexus/src/core/group/extractors/rust-workspace-extractor.ts
+++ b/gitnexus/src/core/group/extractors/rust-workspace-extractor.ts
@@ -31,6 +31,32 @@ interface ImportedSymbol {
   filePath: string;
 }
 
+/**
+ * Linear-time `[package].name = "..."` lookup. The previous regex
+ * `^\[package\]\s*\n(?:[^\[]*?\n)*?name\s*=\s*"([^"]+)"` had a nested
+ * lazy quantifier on `\n` that CodeQL js/redos flagged as exponential
+ * on inputs like `[package]\n` + many bare `\n`. We walk lines
+ * explicitly: scan from the first `[package]` header until we hit the
+ * next `[...]` section header, looking for the `name = "..."` line.
+ * O(n) with the line count.
+ *
+ * Exported so the U8 ReDoS regression test can drive the production
+ * line-walk directly with adversarial fixtures (multi-line strings,
+ * trailing sections, etc.) instead of duplicating it inline.
+ */
+export function parseCargoPackageName(content: string): string | null {
+  const lines = content.split('\n');
+  const packageStart = lines.findIndex((l) => l.trim() === '[package]');
+  if (packageStart < 0) return null;
+  for (let i = packageStart + 1; i < lines.length; i++) {
+    const line = lines[i].trimStart();
+    if (line.startsWith('[')) break; // hit the next section header
+    const m = /^name\s*=\s*"([^"]+)"/.exec(line);
+    if (m) return m[1];
+  }
+  return null;
+}
+
 /**
  * Parse a Cargo.toml to extract the crate name and workspace dependency
  * names. Uses simple line-based parsing — no TOML library needed for
@@ -47,12 +73,9 @@ async function parseCrateManifest(
     return null;
   }
 
-  let name = '';
+  const name = parseCargoPackageName(content) ?? '';
   const workspaceDeps: string[] = [];
 
-  const nameMatch = content.match(/^\[package\]\s*\n(?:[^\[]*?\n)*?name\s*=\s*"([^"]+)"/m);
-  if (nameMatch) name = nameMatch[1];
-
   // Match dependencies that use workspace = true, which indicates they
   // are workspace-internal deps:
   //   dep_name = { workspace = true }
diff --git a/gitnexus/src/core/group/service.ts b/gitnexus/src/core/group/service.ts
index de324e70b..d0473048f 100644
--- a/gitnexus/src/core/group/service.ts
+++ b/gitnexus/src/core/group/service.ts
@@ -65,6 +65,15 @@ export interface GroupToolPort {
       relationTypes: string[];
       minConfidence: number;
       includeTests: boolean;
+      // Optional cancellation signal. Callers (notably the cross-impact
+      // Phase-2 fanout) wrap this call in a Promise.race against a
+      // setTimeout-driven AbortController so a single hung neighbor
+      // cannot exceed the request's clamped timeout budget. Implementors
+      // may honor the signal cooperatively or simply let the caller's
+      // race resolve the await — the latter is sufficient for the
+      // resource-exhaustion mitigation. When the signal is absent or
+      // already aborted at call time, behavior is unchanged.
+      signal?: AbortSignal;
     },
   ): Promise<unknown | null>;
   context(
diff --git a/gitnexus/src/core/ingestion/cobol/cobol-preprocessor.ts b/gitnexus/src/core/ingestion/cobol/cobol-preprocessor.ts
index 23cedb99b..34be6bc03 100644
--- a/gitnexus/src/core/ingestion/cobol/cobol-preprocessor.ts
+++ b/gitnexus/src/core/ingestion/cobol/cobol-preprocessor.ts
@@ -369,9 +369,20 @@ const RE_USE_AFTER =
   /\bUSE\s+(?:AFTER\s+)?(?:STANDARD\s+)?(?:EXCEPTION|ERROR)\s+ON\s+([A-Z][A-Z0-9-]+|INPUT|OUTPUT|I-O|EXTEND)\b/i;
 
 // SET statement (condition, index)
-const RE_SET_TO_TRUE = /\bSET\s+((?:[A-Z][A-Z0-9-]+(?:\s+OF\s+[A-Z][A-Z0-9-]+)?\s+)+)TO\s+TRUE\b/i;
-const RE_SET_INDEX =
-  /\bSET\s+((?:[A-Z][A-Z0-9-]+\s+)+)(TO|UP\s+BY|DOWN\s+BY)\s+(\d+|[A-Z][A-Z0-9-]+)/i;
+//
+// Catastrophic-backtracking note (CodeQL js/redos): the previous shape
+// `((?:[A-Z][A-Z0-9-]+(?:\s+OF\s+[A-Z][A-Z0-9-]+)?\s+)+)TO\s+TRUE`
+// nested `\s+` quantifiers across alternations and was exponential on
+// inputs like "SET a OF a OF a ... TO TRUE". Replaced with a lazy
+// dot-match bounded by the explicit `\s+TO\s+TRUE` suffix — `.+?` is
+// O(n) with the trailing anchor, and the captured group is parsed
+// downstream the same way as before.
+// Exported so the U8 ReDoS regression test can pin the exact production
+// pattern. Direct import is the only way to ensure the test's
+// pathological-input timing assertion exercises the production regex
+// instead of an inline copy that drifts.
+export const RE_SET_TO_TRUE = /\bSET\s+(.+?)\s+TO\s+TRUE\b/i;
+export const RE_SET_INDEX = /\bSET\s+(.+?)\s+(TO|UP\s+BY|DOWN\s+BY)\s+(\d+|[A-Z][A-Z0-9-]+)/i;
 
 // INITIALIZE statement — data reset (captures targets before REPLACING/WITH clause)
 const RE_INITIALIZE = /\bINITIALIZE\s+([\s\S]*?)(?=\bREPLACING\b|\bWITH\b|\.\s*$|$)/i;
diff --git a/gitnexus/src/mcp/local/local-backend.ts b/gitnexus/src/mcp/local/local-backend.ts
index 11f7e61f3..b53034378 100644
--- a/gitnexus/src/mcp/local/local-backend.ts
+++ b/gitnexus/src/mcp/local/local-backend.ts
@@ -2984,8 +2984,14 @@ export class LocalBackend {
       relationTypes: string[];
       minConfidence: number;
       includeTests: boolean;
+      signal?: AbortSignal;
     },
   ): Promise<any | null> {
+    // Honor an already-aborted signal at the entry boundary as a fast
+    // path. Cooperative cancellation inside _runImpactBFS is out of
+    // scope — the caller's Promise.race against the same signal
+    // resolves the await regardless of how long this body runs.
+    if (opts.signal?.aborted) return null;
     try {
       await this.refreshRepos();
       await this.ensureInitialized(repoId);
diff --git a/gitnexus/test/unit/group/cross-impact-phase2-timeout.test.ts b/gitnexus/test/unit/group/cross-impact-phase2-timeout.test.ts
new file mode 100644
index 000000000..90b8a80a2
--- /dev/null
+++ b/gitnexus/test/unit/group/cross-impact-phase2-timeout.test.ts
@@ -0,0 +1,121 @@
+/**
+ * Phase-2 fanout timeout regression test.
+ *
+ * Codex adversarial review on PR #1331 surfaced that `validateGroupImpactParams`
+ * clamps `timeoutMs` and `safeLocalImpact` enforces it on the local leg, but
+ * the Phase-2 cross-repo fanout (`cross-impact.ts:521-526`) awaits each
+ * `port.impactByUid(...)` call without a per-call timeout. A single hung
+ * neighbor pins the request indefinitely; multiple slow neighbors compound
+ * past the clamped budget because each starts before `Date.now() > deadline`.
+ *
+ * This test pins the contract of the mitigation: a `safeNeighborImpact`
+ * helper that races `port.impactByUid` against a remaining-budget timer
+ * and returns `{ value: null, timedOut: true }` when the call cannot
+ * complete in time.
+ *
+ * Direct import + named symbol so this is a real regression net — no
+ * `??`-fallback or dynamic-import dance (the U8 false-green pattern).
+ */
+import { describe, expect, it } from 'vitest';
+import { safeNeighborImpact } from '../../../src/core/group/cross-impact.js';
+import type { GroupToolPort } from '../../../src/core/group/service.js';
+
+const minimalOpts = {
+  maxDepth: 3,
+  relationTypes: [] as string[],
+  minConfidence: 0,
+  includeTests: false,
+};
+
+function makePort(impactByUid: GroupToolPort['impactByUid']): GroupToolPort {
+  return {
+    resolveRepo: async () => {
+      throw new Error('not used');
+    },
+    impact: async () => {
+      throw new Error('not used');
+    },
+    query: async () => {
+      throw new Error('not used');
+    },
+    context: async () => {
+      throw new Error('not used');
+    },
+    impactByUid,
+  };
+}
+
+describe('safeNeighborImpact — Phase-2 fanout per-call timeout', () => {
+  it('returns timedOut=true when impactByUid never resolves, within ~remainingMs', async () => {
+    // Hung neighbor: the promise never resolves. Without the timeout wrap
+    // this would hang the test runner.
+    const port = makePort(() => new Promise(() => {}));
+    const start = performance.now();
+    const result = await safeNeighborImpact(port, 'repo-id', 'uid:1', 'upstream', minimalOpts, 150);
+    const elapsedMs = performance.now() - start;
+    expect(result.timedOut).toBe(true);
+    expect(result.value).toBeNull();
+    // Allow generous slack for slow CI; the contract is "bounded", not
+    // "exactly remainingMs". A regression that drops the timeout entirely
+    // would hang far past 1500ms; a regression that uses the wrong unit
+    // (seconds vs ms) would fire much faster.
+    expect(elapsedMs).toBeGreaterThanOrEqual(140);
+    expect(elapsedMs).toBeLessThan(1500);
+  });
+
+  it('returns the resolved value and timedOut=false on a fast happy path', async () => {
+    const fakeFan = { byDepth: { 1: [{ id: 'u1' }] } };
+    const port = makePort(async () => fakeFan);
+    const result = await safeNeighborImpact(
+      port,
+      'repo-id',
+      'uid:1',
+      'upstream',
+      minimalOpts,
+      1000,
+    );
+    expect(result.timedOut).toBe(false);
+    expect(result.value).toBe(fakeFan);
+  });
+
+  it('returns timedOut=true immediately when remainingMs is 0 and the call still hangs', async () => {
+    // Defensive: even if the caller passes 0, the helper must not block.
+    const port = makePort(() => new Promise(() => {}));
+    const start = performance.now();
+    const result = await safeNeighborImpact(port, 'repo-id', 'uid:1', 'upstream', minimalOpts, 0);
+    const elapsedMs = performance.now() - start;
+    expect(result.timedOut).toBe(true);
+    expect(result.value).toBeNull();
+    // 0ms timeout fires on the next tick — should be well under 50ms even on slow CI.
+    expect(elapsedMs).toBeLessThan(50);
+  });
+
+  it('does not compound across calls — two hung neighbors complete within ~2× remainingMs total', async () => {
+    // The contract is per-call timeout. Two sequential hung calls should
+    // total ~2× remainingMs, not (numNeighbors × remainingMs² / 2) or
+    // anything compounding. A regression that shares one timer across
+    // calls would pass the first test but fail this one.
+    const port = makePort(() => new Promise(() => {}));
+    const start = performance.now();
+    const r1 = await safeNeighborImpact(port, 'repo', 'u1', 'upstream', minimalOpts, 100);
+    const r2 = await safeNeighborImpact(port, 'repo', 'u2', 'upstream', minimalOpts, 100);
+    const elapsedMs = performance.now() - start;
+    expect(r1.timedOut).toBe(true);
+    expect(r2.timedOut).toBe(true);
+    expect(elapsedMs).toBeGreaterThanOrEqual(180);
+    expect(elapsedMs).toBeLessThan(1000);
+  });
+
+  it('propagates an immediate rejection from impactByUid as timedOut=false with null value', async () => {
+    // If the port itself rejects (rather than hangs), the helper should
+    // surface that as a non-timeout failure — the existing fanout block
+    // already handles `if (fan == null)` truncation, so returning null
+    // here keeps that path intact.
+    const port = makePort(async () => {
+      throw new Error('connection refused');
+    });
+    const result = await safeNeighborImpact(port, 'repo', 'u1', 'upstream', minimalOpts, 1000);
+    expect(result.timedOut).toBe(false);
+    expect(result.value).toBeNull();
+  });
+});
diff --git a/gitnexus/test/unit/u8-redos-resource-exhaustion.test.ts b/gitnexus/test/unit/u8-redos-resource-exhaustion.test.ts
new file mode 100644
index 000000000..6dd6d9955
--- /dev/null
+++ b/gitnexus/test/unit/u8-redos-resource-exhaustion.test.ts
@@ -0,0 +1,196 @@
+/**
+ * Regression tests for U8 — closes:
+ *   #186 js/redos             rust-workspace-extractor.ts
+ *   #187 js/redos             cobol-preprocessor.ts
+ *   #184 js/resource-exhaustion cross-impact.ts
+ *
+ * These tests import the production symbols directly. A previous shape
+ * dynamic-imported names that did not exist (`extractRustWorkspace` vs.
+ * the real `extractRustWorkspaceLinks`) and `??`-fell-back to inline
+ * regex copies, so the tests stayed green even when the production
+ * fixes regressed. Static imports + named symbols make a regression in
+ * any of the three sites a hard test failure.
+ */
+import { describe, expect, it } from 'vitest';
+import { RE_SET_TO_TRUE, RE_SET_INDEX } from '../../src/core/ingestion/cobol/cobol-preprocessor.js';
+import { parseCargoPackageName } from '../../src/core/group/extractors/rust-workspace-extractor.js';
+import {
+  clampTimeout,
+  IMPACT_TIMEOUT_MIN_MS,
+  IMPACT_TIMEOUT_MAX_MS,
+} from '../../src/core/group/cross-impact.js';
+
+/**
+ * Time a single regex.exec call. Used by the linearity tests below to
+ * compute a 10k/5k ratio in addition to the absolute <500ms bound.
+ *
+ * Ratio assertions catch sub-exponential O(n²) regressions that fit
+ * inside the absolute cap on warm CI; the absolute cap catches
+ * catastrophic backtracking on cold CI. Two complementary signals.
+ */
+function timeRegex(re: RegExp, input: string): number {
+  // Reset regex.lastIndex for global/sticky regexes — ours are not, but
+  // be defensive in case future shape changes add the `g` flag.
+  re.lastIndex = 0;
+  const start = performance.now();
+  re.exec(input);
+  return performance.now() - start;
+}
+
+function timeFn<T>(fn: () => T): number {
+  const start = performance.now();
+  fn();
+  return performance.now() - start;
+}
+
+// Linear scaling is ~2.0× when input doubles; 3.0× allows generous
+// slack for CI-runner GC and tier-up jitter. An O(n²) regression on a
+// 2× input takes ~4× as long, well outside this bound.
+const LINEAR_RATIO_BOUND = 3.0;
+
+/**
+ * Minimum elapsed time (in ms) below which `performance.now()` ratios
+ * are dominated by scheduler jitter and become meaningless. When both
+ * timed runs come in below this floor, we skip the ratio assertion —
+ * the absolute <500ms bound still catches catastrophic backtracking,
+ * and the next CI run will measure higher absolute times that the
+ * ratio assertion can evaluate reliably.
+ *
+ * Calibrated empirically: a flake on macOS reported ratio 5.29×
+ * between two sub-millisecond measurements (~0.5ms vs ~2.6ms), both
+ * genuinely linear but indistinguishable from noise. 5ms is a
+ * comfortable floor where individual measurements are well-separated
+ * from the ~10-100µs `performance.now()` resolution band.
+ */
+const RATIO_MEASUREMENT_FLOOR_MS = 5;
+
+/**
+ * Assert linear scaling between two timed runs on inputs that differ
+ * by 2×. When measurements are too small to be reliable, the ratio
+ * assertion is skipped (the absolute bound still fires elsewhere).
+ */
+function assertSubLinearRatio(elapsedSmall: number, elapsedLarge: number, label: string): void {
+  if (elapsedSmall < RATIO_MEASUREMENT_FLOOR_MS && elapsedLarge < RATIO_MEASUREMENT_FLOOR_MS) {
+    // Both runs completed faster than the noise floor — the ratio is
+    // not meaningful. The absolute <500ms bound elsewhere in this
+    // describe block still pins linearity; we skip rather than risk a
+    // flake on a genuinely-linear implementation.
+    return;
+  }
+  const ratio = elapsedLarge / Math.max(elapsedSmall, 0.001);
+  if (ratio >= LINEAR_RATIO_BOUND) {
+    throw new Error(
+      `${label}: ratio ${ratio.toFixed(2)}× exceeds bound ${LINEAR_RATIO_BOUND}× ` +
+        `(small=${elapsedSmall.toFixed(2)}ms, large=${elapsedLarge.toFixed(2)}ms)`,
+    );
+  }
+}
+
+describe('cobol-preprocessor RE_SET_TO_TRUE — linear time on pathological input', () => {
+  it('matches in <500ms on 50k repetitions of "A OF A " AND 100k/50k ratio is sub-linear when measurable', () => {
+    // 50k/100k repetitions chosen so timings exceed the
+    // RATIO_MEASUREMENT_FLOOR_MS noise floor on typical CI hardware.
+    // Pre-fix nested-quantifier shape would be exponential here; the
+    // post-fix `.+?` shape is linear (~2× when input doubles).
+    const inputSmall = 'SET ' + 'A OF A '.repeat(50_000) + 'TO TRUE';
+    const inputLarge = 'SET ' + 'A OF A '.repeat(100_000) + 'TO TRUE';
+    const elapsedSmall = timeRegex(RE_SET_TO_TRUE, inputSmall);
+    const elapsedLarge = timeRegex(RE_SET_TO_TRUE, inputLarge);
+    expect(RE_SET_TO_TRUE.exec(inputSmall)).not.toBeNull();
+    expect(elapsedSmall).toBeLessThan(500);
+    expect(elapsedLarge).toBeLessThan(500);
+    assertSubLinearRatio(elapsedSmall, elapsedLarge, 'RE_SET_TO_TRUE');
+  });
+
+  it('still matches a normal SET ... TO TRUE statement', () => {
+    const m = RE_SET_TO_TRUE.exec('SET WS-FLAG TO TRUE');
+    expect(m).not.toBeNull();
+    expect(m?.[1]).toBe('WS-FLAG');
+  });
+});
+
+describe('cobol-preprocessor RE_SET_INDEX — linear time on pathological input', () => {
+  it('rejects in <500ms on 50k tokens with no valid suffix AND 100k/50k ratio is sub-linear when measurable', () => {
+    // Forces backtracking against the (TO|UP\s+BY|DOWN\s+BY) alternation
+    // — the richer pathological surface of the two regexes.
+    const inputSmall = 'SET ' + 'A '.repeat(50_000) + 'X';
+    const inputLarge = 'SET ' + 'A '.repeat(100_000) + 'X';
+    const elapsedSmall = timeRegex(RE_SET_INDEX, inputSmall);
+    const elapsedLarge = timeRegex(RE_SET_INDEX, inputLarge);
+    expect(RE_SET_INDEX.exec(inputSmall)).toBeNull();
+    expect(elapsedSmall).toBeLessThan(500);
+    expect(elapsedLarge).toBeLessThan(500);
+    assertSubLinearRatio(elapsedSmall, elapsedLarge, 'RE_SET_INDEX');
+  });
+
+  it('still matches a normal SET INDEX statement', () => {
+    const m = RE_SET_INDEX.exec('SET WS-IDX TO 5');
+    expect(m).not.toBeNull();
+    expect(m?.[1]).toBe('WS-IDX');
+    expect(m?.[2]).toBe('TO');
+    expect(m?.[3]).toBe('5');
+  });
+});
+
+describe('rust-workspace parseCargoPackageName — linear-time line walk', () => {
+  it('extracts the package name in <500ms on 100k blank lines AND 200k/100k ratio is sub-linear when measurable', () => {
+    // 100k/200k blank lines chosen so timings exceed the
+    // RATIO_MEASUREMENT_FLOOR_MS noise floor. Earlier 10k/20k pairing
+    // produced sub-millisecond measurements where scheduler jitter
+    // dominated and the ratio became meaningless (a real macOS run
+    // saw 5.29× between two genuinely-linear sub-ms measurements).
+    const cargoTomlSmall =
+      '[package]\n' + '\n'.repeat(100_000) + 'name = "myrepo"\nversion = "0.1.0"\n';
+    const cargoTomlLarge =
+      '[package]\n' + '\n'.repeat(200_000) + 'name = "myrepo"\nversion = "0.1.0"\n';
+    const elapsedSmall = timeFn(() => parseCargoPackageName(cargoTomlSmall));
+    const elapsedLarge = timeFn(() => parseCargoPackageName(cargoTomlLarge));
+    expect(parseCargoPackageName(cargoTomlSmall)).toBe('myrepo');
+    expect(elapsedSmall).toBeLessThan(500);
+    expect(elapsedLarge).toBeLessThan(500);
+    assertSubLinearRatio(elapsedSmall, elapsedLarge, 'parseCargoPackageName');
+  });
+
+  it('returns null when [package] section is absent', () => {
+    expect(parseCargoPackageName('[workspace]\nmembers = ["a"]\n')).toBeNull();
+  });
+
+  it('stops at the next section header (does not pick up a name= from a later section)', () => {
+    const toml = '[package]\nversion = "1.0"\n[other]\nname = "wrong"\n';
+    expect(parseCargoPackageName(toml)).toBeNull();
+  });
+
+  it('extracts the name from a normal [package] section', () => {
+    const toml = '[package]\nname = "real-crate"\nversion = "0.1.0"\n';
+    expect(parseCargoPackageName(toml)).toBe('real-crate');
+  });
+});
+
+describe('cross-impact clampTimeout — bounds user-supplied impact timeouts', () => {
+  it('rejects negative and zero timeouts, returning MIN', () => {
+    expect(clampTimeout(0)).toBe(IMPACT_TIMEOUT_MIN_MS);
+    expect(clampTimeout(-1)).toBe(IMPACT_TIMEOUT_MIN_MS);
+    expect(clampTimeout(-999_999)).toBe(IMPACT_TIMEOUT_MIN_MS);
+  });
+
+  it('rejects NaN/Infinity, returning MIN', () => {
+    expect(clampTimeout(NaN)).toBe(IMPACT_TIMEOUT_MIN_MS);
+    expect(clampTimeout(Infinity)).toBe(IMPACT_TIMEOUT_MIN_MS);
+    expect(clampTimeout(-Infinity)).toBe(IMPACT_TIMEOUT_MIN_MS);
+  });
+
+  it('caps very large timeouts at MAX (5 minutes)', () => {
+    expect(clampTimeout(999_999_999)).toBe(IMPACT_TIMEOUT_MAX_MS);
+    expect(clampTimeout(IMPACT_TIMEOUT_MAX_MS + 1)).toBe(IMPACT_TIMEOUT_MAX_MS);
+  });
+
+  it('passes through a reasonable timeout unchanged (truncated to integer)', () => {
+    expect(clampTimeout(30_000)).toBe(30_000);
+    expect(clampTimeout(30_500.7)).toBe(30_500);
+  });
+
+  it('floors below-MIN positive values to MIN', () => {
+    expect(clampTimeout(50)).toBe(IMPACT_TIMEOUT_MIN_MS);
+    expect(clampTimeout(0.1)).toBe(IMPACT_TIMEOUT_MIN_MS);
+  });
+});