diff --git a/.changeset/daring-yaks-zip.md b/.changeset/daring-yaks-zip.md
new file mode 100644
index 000000000..b290408a1
--- /dev/null
+++ b/.changeset/daring-yaks-zip.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 538
+---
+**`/gsd-plan-phase` §13e post-planning gap analysis now scopes to the phase's mapped REQ-IDs** — a phase that maps no requirements (`phase_req_ids` null/TBD) no longer reports every unrelated project requirement as "not covered". CONTEXT.md decisions remain in scope. Mapped REQ-IDs that are listed in the roadmap but absent from `REQUIREMENTS.md` are now surfaced as explicit "⚠ Missing from REQUIREMENTS.md" rows instead of being silently dropped, preventing false "all covered" reports when the requirements document has drifted.
diff --git a/get-shit-done/bin/lib/gap-checker.cjs b/get-shit-done/bin/lib/gap-checker.cjs
index cd8e35054..16239ba4e 100644
--- a/get-shit-done/bin/lib/gap-checker.cjs
+++ b/get-shit-done/bin/lib/gap-checker.cjs
@@ -99,7 +99,9 @@ function formatGapTable(rows) {
   }
   const header = '| Source | Item | Status |\n|--------|------|--------|';
   const body = rows.map(r => {
-    const tick = r.status === 'Covered' ? '\u2713 Covered' : '\u2717 Not covered';
+    const tick = r.status === 'Covered' ? '\u2713 Covered'
+      : r.status === 'Missing from REQUIREMENTS.md' ? '\u26a0 Missing from REQUIREMENTS.md'
+      : '\u2717 Not covered';
     return `| ${r.source} | ${r.item} | ${tick} |`;
   }).join('\n');
   return `## Post-Planning Gap Analysis\n\n${header}\n${body}\n`;
@@ -116,7 +118,30 @@ function readGate(cwd) {
   return true;
 }
 
-function runGapAnalysis(cwd, phaseDir) {
+/**
+ * Normalize a raw `--phase-req-ids` argument into the scoping signal used by
+ * runGapAnalysis (#447). Mirrors §13's null/TBD skip semantics.
+ *
+ *   undefined           → flag absent: compare the whole REQUIREMENTS.md (back-compat)
+ *   null | '' | TBD     → no requirements mapped to this phase: skip the comparison
+ *   "REQ-01,REQ-02"     → restrict the comparison to these IDs
+ *
+ * Tolerates JSON-array-ish input (`["REQ-01","REQ-02"]`) since callers may pass
+ * the roadmap value through verbatim.
+ */
+function normalizePhaseReqIds(rawVal) {
+  if (rawVal === undefined) return undefined;
+  if (rawVal === null) return null;
+  const v = String(rawVal).replace(/["'[\]()]/g, '').trim();
+  if (v === '' || /^(null|tbd|none)$/i.test(v)) return null;
+  // Tolerate comma-, space-, or newline-separated lists (callers may pass the
+  // roadmap value verbatim, whose serialization is not guaranteed).
+  const ids = v.split(/[\s,]+/).map(s => s.trim()).filter(Boolean);
+  return ids.length === 0 ? null : ids;
+}
+
+function runGapAnalysis(cwd, phaseDir, options = {}) {
+  const phaseReqIds = normalizePhaseReqIds(options.phaseReqIds);
   if (!readGate(cwd)) {
     return {
       enabled: false,
@@ -131,7 +156,21 @@ function runGapAnalysis(cwd, phaseDir) {
 
   const reqPath = planningPaths(cwd).requirements;
   const reqMd = fs.existsSync(reqPath) ? fs.readFileSync(reqPath, 'utf-8') : '';
-  const reqItems = parseRequirements(reqMd).map(r => ({ ...r, source: 'REQUIREMENTS.md' }));
+  let reqItems = parseRequirements(reqMd).map(r => ({ ...r, source: 'REQUIREMENTS.md' }));
+
+  // Scope the requirements comparison to the phase's mapped REQ-IDs (#447).
+  // A phase that maps no requirements (phase_req_ids null/TBD) must not report
+  // every unrelated project REQ-ID as a gap — mirror §13's skip behavior.
+  // CONTEXT.md decisions (below) are always in scope regardless.
+  let ghostReqIds = [];
+  if (phaseReqIds === null) {
+    reqItems = [];
+  } else if (Array.isArray(phaseReqIds)) {
+    const wanted = new Set(phaseReqIds);
+    const foundIds = new Set(reqItems.map(r => r.id));
+    reqItems = reqItems.filter(r => wanted.has(r.id));
+    ghostReqIds = phaseReqIds.filter(id => !foundIds.has(id));
+  }
 
   // Read the phase directory once; reuse the listing for both context detection
   // and plan-file enumeration (avoids redundant readdirSync calls).
@@ -168,9 +207,12 @@ function runGapAnalysis(cwd, phaseDir) {
     };
   }
 
-  const rows = sortRows(detectCoverage(items, planText));
-  const uncovered = rows.filter(r => r.status === 'Not covered').length;
-  const covered = rows.length - uncovered;
+  const rows = sortRows([
+    ...detectCoverage(items, planText),
+    ...ghostReqIds.map(id => ({ source: 'REQUIREMENTS.md', item: id, status: 'Missing from REQUIREMENTS.md' })),
+  ]);
+  const covered = rows.filter(r => r.status === 'Covered').length;
+  const uncovered = rows.length - covered;
 
   const summary = uncovered === 0
     ? `\u2713 All ${rows.length} items covered by plans`
@@ -191,7 +233,13 @@ function cmdGapAnalysis(cwd, args, raw) {
     error('Usage: gap-analysis --phase-dir <path-to-phase-directory>');
   }
   const phaseDir = args[idx + 1];
-  const result = runGapAnalysis(cwd, phaseDir);
+
+  // Optional --phase-req-ids scopes the requirements comparison (#447).
+  // Absent → compare the whole REQUIREMENTS.md (back-compat).
+  const reqIdx = args.indexOf('--phase-req-ids');
+  const phaseReqIds = reqIdx === -1 ? undefined : (args[reqIdx + 1] ?? '');
+
+  const result = runGapAnalysis(cwd, phaseDir, { phaseReqIds });
   output(result, raw, result.table || result.summary);
 }
 
@@ -200,6 +248,7 @@ module.exports = {
   detectCoverage,
   formatGapTable,
   sortRows,
+  normalizePhaseReqIds,
   runGapAnalysis,
   cmdGapAnalysis,
 };
diff --git a/get-shit-done/workflows/plan-phase.md b/get-shit-done/workflows/plan-phase.md
index 557e94ef7..eb6be4b0d 100644
--- a/get-shit-done/workflows/plan-phase.md
+++ b/get-shit-done/workflows/plan-phase.md
@@ -1627,7 +1627,8 @@ one place before execution begins.
 ```bash
 POST_PLANNING_GAPS=$(gsd_run query config-get workflow.post_planning_gaps --default true 2>/dev/null || echo true)
 if [ "$POST_PLANNING_GAPS" = "true" ]; then
-  node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" gap-analysis --phase-dir "${PHASE_DIR}"
+  # Scope to this phase's mapped REQ-IDs (#447); null/TBD skips the requirements comparison (CONTEXT.md decisions still reported), mirroring §13.
+  node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" gap-analysis --phase-dir "${PHASE_DIR}" --phase-req-ids "$(node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" query init.plan-phase "$PHASE" --pick phase_req_ids 2>/dev/null || echo TBD)"
 fi
 ```
 
diff --git a/tests/bug-447-gap-analysis-phase-req-ids.test.cjs b/tests/bug-447-gap-analysis-phase-req-ids.test.cjs
new file mode 100644
index 000000000..be5a59481
--- /dev/null
+++ b/tests/bug-447-gap-analysis-phase-req-ids.test.cjs
@@ -0,0 +1,226 @@
+'use strict';
+
+/**
+ * Bug #447: plan-phase §13e gap-analysis ignores phase_req_ids → false-positive
+ * coverage gaps.
+ *
+ * Root cause: runGapAnalysis() diffs the ENTIRE REQUIREMENTS.md against the
+ * phase's plans, with no awareness of phase_req_ids. §13 (Requirements Coverage
+ * Gate) skips when phase_req_ids is null/TBD, but §13e never inherited that
+ * scoping contract — so a phase that maps no requirements reports every
+ * unrelated project REQ-ID as "Not covered".
+ *
+ * Fix: teach the gap-analysis CLI a --phase-req-ids option (the durable home for
+ * the scoping contract), mirroring §13:
+ *   - null / TBD / empty  → skip the REQUIREMENTS.md comparison entirely
+ *                           (CONTEXT.md decisions are still reported).
+ *   - explicit ID list    → restrict the comparison to those IDs.
+ *   - flag absent         → backward-compatible (compare the whole file).
+ */
+
+const { describe, test, beforeEach, afterEach } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const path = require('path');
+const { runGsdTools, createTempProject, cleanup } = require('./helpers.cjs');
+
+describe('gap-analysis --phase-req-ids scoping (#447)', () => {
+  let tmpDir;
+  let phaseDir;
+
+  function writeRequirements(ids) {
+    const lines = ids.map((id, i) => `- [ ] **${id}** Requirement ${i + 1} description`);
+    fs.writeFileSync(path.join(tmpDir, '.planning', 'REQUIREMENTS.md'),
+      `# Requirements\n\n${lines.join('\n')}\n`);
+  }
+
+  function writeContext(decisions) {
+    const dLines = decisions.map(d => `- **${d.id}:** ${d.text}`).join('\n');
+    fs.writeFileSync(path.join(phaseDir, 'CONTEXT.md'),
+      `# Phase Context\n\n<decisions>\n## Implementation Decisions\n\n${dLines}\n</decisions>\n`);
+  }
+
+  function writePlan(name, body) {
+    fs.writeFileSync(path.join(phaseDir, `${name}-PLAN.md`), body);
+  }
+
+  function reqRows(out) {
+    return out.rows.filter(r => r.source === 'REQUIREMENTS.md').map(r => r.item);
+  }
+
+  beforeEach(() => {
+    tmpDir = createTempProject();
+    phaseDir = path.join(tmpDir, '.planning', 'phases', '01-test');
+    fs.mkdirSync(phaseDir, { recursive: true });
+    const r = runGsdTools('config-ensure-section', tmpDir);
+    assert.ok(r.success, `config-ensure-section failed: ${r.error}`);
+  });
+
+  afterEach(() => cleanup(tmpDir));
+
+  // ── The core bug ─────────────────────────────────────────────────────────────
+
+  test('phase mapping no REQs (--phase-req-ids TBD) reports zero REQUIREMENTS.md rows', () => {
+    // A REQUIREMENTS.md full of IDs that belong to OTHER phases/milestones.
+    writeRequirements(['BACK-01', 'WEB-03', 'API-07', 'DATA-02']);
+    writePlan('01', '# Plan 1\n\nStandalone phase, maps no project requirements.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'TBD'], tmpDir);
+    assert.ok(r.success, `gap-analysis failed: ${r.error}`);
+    const out = JSON.parse(r.output);
+
+    assert.deepStrictEqual(reqRows(out), [],
+      'a phase that maps no REQ-IDs must not report unrelated project requirements as gaps');
+    assert.strictEqual(out.counts.uncovered, 0,
+      'no false-positive "not covered" rows for an unmapped phase');
+  });
+
+  test('--phase-req-ids null behaves the same as TBD (skip requirements)', () => {
+    writeRequirements(['BACK-01', 'WEB-03']);
+    writePlan('01', '# Plan\n\nNo mapped reqs.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'null'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out), []);
+  });
+
+  // ── Scoped to a mapped subset ────────────────────────────────────────────────
+
+  test('explicit ID list restricts the comparison to those REQ-IDs', () => {
+    writeRequirements(['REQ-01', 'REQ-02', 'REQ-03']);
+    // Plan covers REQ-01 only; REQ-02 is mapped to the phase but not yet addressed.
+    writePlan('01', '# Plan\n\nImplements REQ-01 only.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'REQ-01,REQ-02'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+
+    assert.deepStrictEqual(reqRows(out).sort(), ['REQ-01', 'REQ-02'],
+      'only the phase-mapped REQ-IDs are considered; REQ-03 (another phase) is excluded');
+    const req01 = out.rows.find(x => x.item === 'REQ-01');
+    const req02 = out.rows.find(x => x.item === 'REQ-02');
+    assert.strictEqual(req01.status, 'Covered');
+    assert.strictEqual(req02.status, 'Not covered');
+  });
+
+  test('JSON-array-ish value (["REQ-01"]) is tolerated and scoped', () => {
+    writeRequirements(['REQ-01', 'REQ-02']);
+    writePlan('01', '# Plan\n\nImplements REQ-01.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', '["REQ-01"]'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out), ['REQ-01']);
+  });
+
+  // ── CONTEXT.md decisions are unaffected by req scoping ───────────────────────
+
+  test('CONTEXT.md decisions are still reported when requirements are skipped', () => {
+    writeRequirements(['BACK-01', 'WEB-03']);
+    writeContext([{ id: 'D-01', text: 'Use a local notification daemon' }]);
+    writePlan('01', '# Plan\n\nUnrelated work, no decisions addressed.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'TBD'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+
+    assert.deepStrictEqual(reqRows(out), [], 'requirements skipped');
+    const d01 = out.rows.find(x => x.item === 'D-01');
+    assert.ok(d01, 'CONTEXT.md decision D-01 must still be reported');
+    assert.strictEqual(d01.source, 'CONTEXT.md');
+    assert.strictEqual(d01.status, 'Not covered');
+  });
+
+  // ── Parser robustness (workflow passes the roadmap value verbatim) ───────────
+
+  test('whitespace/newline-separated IDs are tolerated and scoped', () => {
+    writeRequirements(['REQ-01', 'REQ-02', 'REQ-03']);
+    writePlan('01', '# Plan\n\nImplements the first one.\n');
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'REQ-01 REQ-02\nREQ-03'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out).sort(), ['REQ-01', 'REQ-02', 'REQ-03']);
+  });
+
+  // ── Backward compatibility ───────────────────────────────────────────────────
+
+  test('flag absent → whole REQUIREMENTS.md is compared (unchanged behavior)', () => {
+    writeRequirements(['REQ-01', 'REQ-02']);
+    writePlan('01', '# Plan\n\nImplements REQ-01 only.\n');
+
+    const r = runGsdTools(['gap-analysis', '--phase-dir', phaseDir], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out).sort(), ['REQ-01', 'REQ-02'],
+      'with no --phase-req-ids, all requirements are still reported (back-compat)');
+  });
+
+  // ── §13e wiring: init.plan-phase --pick phase_req_ids → gap-analysis ─────────
+  // Guards the exact query the workflow uses. `roadmap.get-phase` returns raw
+  // phase TEXT (not JSON), so --pick yields nothing there; the scoping value
+  // must come from `init.plan-phase`. This test would have caught using the
+  // wrong query (which silently skips requirements for every phase).
+
+  function writeRoadmap(reqLine) {
+    fs.writeFileSync(path.join(tmpDir, '.planning', 'ROADMAP.md'),
+      `# Roadmap\n\n## Phase 1: Test Phase\n**Goal:** Do the thing\n${reqLine}**Success Criteria:**\n- It works\n`);
+  }
+
+  test('init.plan-phase --pick phase_req_ids exposes the mapped IDs, and gap-analysis scopes to them', () => {
+    writeRoadmap('**Requirements:** REQ-01, REQ-02\n');
+    writeRequirements(['REQ-01', 'REQ-02', 'REQ-03']);
+    writePlan('01', '# Plan\n\nImplements the first requirement only.\n');
+
+    const q = runGsdTools(['query', 'init.plan-phase', '1', '--pick', 'phase_req_ids'], tmpDir);
+    assert.ok(q.success, `init.plan-phase query failed: ${q.error}`);
+    const ids = q.output.trim();
+    assert.match(ids, /REQ-01/, 'init.plan-phase must expose phase_req_ids (roadmap.get-phase does NOT)');
+
+    const r = runGsdTools(['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', ids], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out).sort(), ['REQ-01', 'REQ-02'],
+      'gap report is scoped to the phase-mapped IDs; REQ-03 (another phase) is excluded');
+  });
+
+  test('mapped REQ-ID absent from REQUIREMENTS.md appears as "Missing" row, not silently dropped', () => {
+    writeRequirements(['REQ-01']);
+    writePlan('01', '# Plan\n\nImplements REQ-01.\n');
+
+    const r = runGsdTools(
+      ['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', 'REQ-01,REQ-99'], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+
+    assert.deepStrictEqual(reqRows(out).sort(), ['REQ-01', 'REQ-99'],
+      'REQ-99 (absent from REQUIREMENTS.md) must be present in the report, not silently dropped');
+    const req99 = out.rows.find(x => x.item === 'REQ-99');
+    assert.ok(req99, 'missing mapped ID must have an output row');
+    assert.strictEqual(req99.status, 'Missing from REQUIREMENTS.md');
+    assert.ok(out.counts.uncovered > 0, 'uncovered count must reflect the missing mapped ID');
+  });
+
+  test('phase with no Requirements line → init.plan-phase yields empty → gap-analysis skips requirements', () => {
+    writeRoadmap(''); // no **Requirements:** line
+    writeRequirements(['REQ-01', 'REQ-02']);
+    writePlan('01', '# Plan\n\nStandalone phase.\n');
+
+    const q = runGsdTools(['query', 'init.plan-phase', '1', '--pick', 'phase_req_ids'], tmpDir);
+    assert.ok(q.success, q.error);
+    const ids = q.output.trim(); // expected empty
+
+    // The workflow passes the (possibly empty) value through verbatim.
+    const r = runGsdTools(['gap-analysis', '--phase-dir', phaseDir, '--phase-req-ids', ids], tmpDir);
+    assert.ok(r.success, r.error);
+    const out = JSON.parse(r.output);
+    assert.deepStrictEqual(reqRows(out), [],
+      'an unmapped phase reports no requirement gaps (the original #447 bug)');
+  });
+});