diff --git a/test/helpers/e2e-helpers.test.ts b/test/helpers/e2e-helpers.test.ts
index 0dc1b8ce0..a5d252daf 100644
--- a/test/helpers/e2e-helpers.test.ts
+++ b/test/helpers/e2e-helpers.test.ts
@@ -78,6 +78,35 @@ describe('matchesUnnegated', () => {
     expect(matchesUnnegated('This cannot promote the payload into columns.', splitPattern)).toBe(false);
   });
 
+  test('recognizes a typographic curly apostrophe ("doesn’t") as a negation', () => {
+    // LLM prose commonly renders contractions with U+2019 rather than the
+    // ASCII apostrophe — a plain [a-z]+n't pattern misses this entirely.
+    expect(matchesUnnegated(
+      'This doesn’t need extraction — promote the payload to explicit columns is unnecessary here.',
+      /promote the payload to explicit columns/i,
+    )).toBe(false);
+  });
+
+  test('does not let an abbreviation period (e.g., i.e., etc.) hide an earlier negation', () => {
+    // A bare lastIndexOf('.') treats every period as a sentence break,
+    // including ones inside abbreviations — which would incorrectly cut the
+    // negation lookback window short and hide "not" from the scan.
+    expect(matchesUnnegated(
+      'I would not recommend, e.g., promoting this payload to explicit columns.',
+      /promoting this payload to explicit columns/i,
+    )).toBe(false);
+  });
+
+  test('still treats a real sentence boundary as a boundary (does not over-widen the window)', () => {
+    // Guards against overcorrecting the abbreviation fix into ignoring
+    // genuine sentence breaks — an earlier, unrelated negation must NOT
+    // suppress a later, unnegated positive match.
+    expect(matchesUnnegated(
+      'This is not a JSONField concern. Separately, I recommend you promote the payload into explicit columns.',
+      /promote the payload into explicit columns/i,
+    )).toBe(true);
+  });
+
   test('catches a positive match even when an unrelated negation appears earlier in the text', () => {
     expect(matchesUnnegated(
       'This is not a JSONField concern. Separately, I recommend you promote the payload into explicit columns.',
diff --git a/test/helpers/e2e-helpers.ts b/test/helpers/e2e-helpers.ts
index b0187c2c0..c675d0319 100644
--- a/test/helpers/e2e-helpers.ts
+++ b/test/helpers/e2e-helpers.ts
@@ -133,6 +133,28 @@ export function setupPlanEngReviewFixture(tmpPrefix: string, planMarkdown: strin
   return planDir;
 }
 
+/**
+ * Prompt for the data-model-bias/legitimate-json/measured-denorm/minimal-change
+ * E2E blocks (paired with setupPlanEngReviewFixture). Pins the ABSOLUTE path to
+ * the sandboxed SKILL.md and explicitly forbids reading any other SKILL.md —
+ * especially not the operator's globally-installed ~/.claude/skills/gstack —
+ * because plan-eng-review/SKILL.md's own STOP-Read directive references that
+ * absolute path for its carved sections/ file. Without this, a machine that
+ * has gstack installed globally could have the agent read (and get graded
+ * against) the REAL installed skill instead of this branch's copy, silently
+ * defeating the whole point of the sandbox.
+ */
+export function planEngReviewDataModelPrompt(planDir: string, focusSentence: string): string {
+  const skillPath = path.join(planDir, 'plan-eng-review', 'SKILL.md');
+  return `Read the ONLY skill file you may read, this absolute path: ${skillPath}. Do NOT Glob, find, or search for any other SKILL.md anywhere — especially nothing under ~/.claude or /Users. Follow its review workflow for this scenario.
+
+Read plan.md — that's the plan to review. This is a standalone plan document, not a codebase — skip any codebase exploration steps.
+
+Proceed directly to the architecture review section. Skip any AskUserQuestion calls — this is non-interactive. Write your complete architecture review directly to ${planDir}/review-output.md
+
+${focusSentence}`;
+}
+
 /**
  * Case-insensitive check for `pattern` in `text` that ignores matches
  * immediately preceded by a negation word (not/n't/no/never/without/...).
@@ -161,16 +183,27 @@ export function matchesUnnegated(text: string, pattern: RegExp): boolean {
   // alternative can never match mid-word (there's no word boundary between
   // the letters immediately before "n" and "n" itself), so it silently
   // covered nothing beyond the contractions already spelled out explicitly.
-  const NEGATION = /\b(not|no|never|cannot|without|against|rather than|instead of)\b|[a-z]+n't\b/i;
+  // [a-z]+n['’]t matches both the ASCII apostrophe and the typographic
+  // curly one (’, U+2019) — LLM prose commonly renders contractions with the
+  // curly form, and this codebase already hit this exact gotcha once before
+  // (see the apostrophe wildcard note in test/spec-template-invariants.test.ts).
+  const NEGATION = /\b(not|no|never|cannot|without|against|rather than|instead of)\b|[a-z]+n['’]t\b/i;
   const flags = pattern.flags.includes('g') ? pattern.flags : pattern.flags + 'g';
   const re = new RegExp(pattern.source, flags);
+  // Real sentence-ending punctuation is followed by whitespace + a capital
+  // letter, or sits at the end of the string — this excludes periods inside
+  // abbreviations ("e.g.", "i.e.", "etc."), decimals, and version strings,
+  // which a bare lastIndexOf('.') would wrongly treat as a sentence break
+  // and use to hide an earlier negation word from the lookback window.
+  const SENTENCE_END = /[.!?](?=\s+[A-Z]|\s*$)/g;
   let m: RegExpExecArray | null;
   while ((m = re.exec(text))) {
-    const sentenceStart = Math.max(
-      text.lastIndexOf('.', m.index),
-      text.lastIndexOf('!', m.index),
-      text.lastIndexOf('?', m.index),
-    ) + 1;
+    let sentenceStart = 0;
+    let em: RegExpExecArray | null;
+    SENTENCE_END.lastIndex = 0;
+    while ((em = SENTENCE_END.exec(text)) && em.index < m.index) {
+      sentenceStart = em.index + 1;
+    }
     const preceding = text.slice(sentenceStart, m.index);
     if (!NEGATION.test(preceding)) return true;
     if (re.lastIndex === m.index) re.lastIndex++; // avoid infinite loop on zero-width matches
diff --git a/test/helpers/touchfiles.ts b/test/helpers/touchfiles.ts
index ea58bf4ab..accb47962 100644
--- a/test/helpers/touchfiles.ts
+++ b/test/helpers/touchfiles.ts
@@ -89,10 +89,13 @@ export const E2E_TOUCHFILES: Record<string, string[]> = {
   'plan-ceo-review-expansion-energy': ['plan-ceo-review/**', 'scripts/resolvers/preamble.ts', 'test/fixtures/mode-posture/**', 'test/helpers/llm-judge.ts'],
   'plan-eng-review':           ['plan-eng-review/**'],
   'plan-eng-review-artifact':  ['plan-eng-review/**'],
-  'plan-eng-review-data-model-bias': ['plan-eng-review/**'],
-  'plan-eng-review-data-model-legitimate-json': ['plan-eng-review/**'],
-  'plan-eng-review-data-model-measured-denorm': ['plan-eng-review/**'],
-  'plan-eng-review-data-model-minimal-change': ['plan-eng-review/**'],
+  // Behavior lives partly in test/helpers/e2e-helpers.ts (setupPlanEngReviewFixture,
+  // matchesUnnegated, planEngReviewDataModelPrompt) — without this, a regression
+  // in that shared helper wouldn't get these tests re-selected by diff-based CI.
+  'plan-eng-review-data-model-bias': ['plan-eng-review/**', 'test/helpers/e2e-helpers.ts'],
+  'plan-eng-review-data-model-legitimate-json': ['plan-eng-review/**', 'test/helpers/e2e-helpers.ts'],
+  'plan-eng-review-data-model-measured-denorm': ['plan-eng-review/**', 'test/helpers/e2e-helpers.ts'],
+  'plan-eng-review-data-model-minimal-change': ['plan-eng-review/**', 'test/helpers/e2e-helpers.ts'],
   'plan-review-report':        ['plan-eng-review/**', 'scripts/gen-skill-docs.ts'],
 
   // Plan-mode smoke tests — gate-tier safety regression tests. Each test file
diff --git a/test/skill-e2e-plan.test.ts b/test/skill-e2e-plan.test.ts
index 4004b6197..76dfe110b 100644
--- a/test/skill-e2e-plan.test.ts
+++ b/test/skill-e2e-plan.test.ts
@@ -5,7 +5,7 @@ import {
   describeIfSelected, testConcurrentIfSelected,
   copyDirSync, setupBrowseShims, logCost, recordE2E,
   createEvalCollector, finalizeEvalCollector,
-  setupPlanEngReviewFixture, matchesUnnegated,
+  setupPlanEngReviewFixture, matchesUnnegated, planEngReviewDataModelPrompt,
 } from './helpers/e2e-helpers';
 import { judgePosture } from './helpers/llm-judge';
 import { spawnSync } from 'child_process';
@@ -424,13 +424,10 @@ column-add, no new FK navigation in the codebase.
 
   testConcurrentIfSelected('plan-eng-review-data-model-bias', async () => {
     const result = await runSkillTest({
-      prompt: `Read plan-eng-review/SKILL.md for the review workflow.
-
-Read plan.md — that's the plan to review. This is a standalone plan document, not a codebase — skip any codebase exploration steps.
-
-Proceed directly to the architecture review section. Skip any AskUserQuestion calls — this is non-interactive. Write your complete architecture review directly to ${planDir}/review-output.md
-
-Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.`,
+      prompt: planEngReviewDataModelPrompt(
+        planDir,
+        'Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.',
+      ),
       workingDirectory: planDir,
       maxTurns: 15,
       timeout: 360_000,
@@ -543,13 +540,10 @@ response verbatim for audit/replay, not to model our own domain state.
 
   testConcurrentIfSelected('plan-eng-review-data-model-legitimate-json', async () => {
     const result = await runSkillTest({
-      prompt: `Read plan-eng-review/SKILL.md for the review workflow.
-
-Read plan.md — that's the plan to review. This is a standalone plan document, not a codebase — skip any codebase exploration steps.
-
-Proceed directly to the architecture review section. Skip any AskUserQuestion calls — this is non-interactive. Write your complete architecture review directly to ${planDir}/review-output.md
-
-Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.`,
+      prompt: planEngReviewDataModelPrompt(
+        planDir,
+        'Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.',
+      ),
       workingDirectory: planDir,
       maxTurns: 15,
       timeout: 360_000,
@@ -643,13 +637,10 @@ not a general schema change.
 
   testConcurrentIfSelected('plan-eng-review-data-model-measured-denorm', async () => {
     const result = await runSkillTest({
-      prompt: `Read plan-eng-review/SKILL.md for the review workflow.
-
-Read plan.md — that's the plan to review. This is a standalone plan document, not a codebase — skip any codebase exploration steps.
-
-Proceed directly to the architecture review section. Skip any AskUserQuestion calls — this is non-interactive. Write your complete architecture review directly to ${planDir}/review-output.md
-
-Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.`,
+      prompt: planEngReviewDataModelPrompt(
+        planDir,
+        'Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.',
+      ),
       workingDirectory: planDir,
       maxTurns: 15,
       timeout: 360_000,
@@ -738,13 +729,10 @@ when the verification email link is clicked.
 
   testConcurrentIfSelected('plan-eng-review-data-model-minimal-change', async () => {
     const result = await runSkillTest({
-      prompt: `Read plan-eng-review/SKILL.md for the review workflow.
-
-Read plan.md — that's the plan to review. This is a standalone plan document, not a codebase — skip any codebase exploration steps.
-
-Proceed directly to the architecture review section. Skip any AskUserQuestion calls — this is non-interactive. Write your complete architecture review directly to ${planDir}/review-output.md
-
-Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.`,
+      prompt: planEngReviewDataModelPrompt(
+        planDir,
+        'Focus specifically on the data model design in the plan. Apply the data model review checklist from the skill.',
+      ),
       workingDirectory: planDir,
       maxTurns: 15,
       timeout: 360_000,