diff --git a/.changeset/clever-lemurs-snooze.md b/.changeset/clever-lemurs-snooze.md
new file mode 100644
index 000000000..cd261c26c
--- /dev/null
+++ b/.changeset/clever-lemurs-snooze.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 2975
+---
+**`windows append`/`waive`/`fixed` no longer destroy prose below the JSON ledger** — the writer reconstructed the file from the parsed JSON ledger only, silently dropping any human-authored prose sections below the closing fence. The writer now preserves trailing prose across all write operations. (#2893)
diff --git a/src/broken-windows.cts b/src/broken-windows.cts
index 8c70b238a..032c4e6b7 100644
--- a/src/broken-windows.cts
+++ b/src/broken-windows.cts
@@ -721,7 +721,33 @@ function writeLedgerAtomic(cwd: string, ledger: Ledger): void {
   ensurePlanningDir(cwd);
   const p = ledgerPath(cwd);
   const tmp = `${p}.${process.pid}.tmp`;
-  fs.writeFileSync(tmp, renderLedger(ledger), 'utf8');
+
+  // #2893: preserve any prose below the JSON ledger block. renderLedger
+  // reconstructs frontmatter + header + table + JSON — it does not include
+  // trailing prose that users may have written below the closing fence.
+  // Without this, every append/waive/fixed silently destroys that prose.
+  let trailingProse = '';
+  try {
+    const existing = fs.readFileSync(p, 'utf8');
+    // #2893: search for the CLOSING fence starting AFTER the opening fence,
+    // mirroring parseJsonBlock — indexOf(JSON_FENCE_CLOSE) alone would match
+    // the opening fence ('````json' starts with '````').
+    const openIdx = existing.indexOf(JSON_FENCE_OPEN);
+    if (openIdx !== -1) {
+      const fenceEnd = existing.indexOf(JSON_FENCE_CLOSE, openIdx + JSON_FENCE_OPEN.length);
+      if (fenceEnd !== -1) {
+        const afterFence = existing.slice(fenceEnd + JSON_FENCE_CLOSE.length);
+        // Drop leading newlines; keep the rest as prose.
+        trailingProse = afterFence.replace(/^\n+/, '');
+      }
+    }
+  } catch {
+    // File doesn't exist yet (first write) — no prose to preserve.
+  }
+
+  const rendered = renderLedger(ledger);
+  const content = trailingProse ? `${rendered}${trailingProse}` : rendered;
+  fs.writeFileSync(tmp, content, 'utf8');
   try {
     renameWithRetry(tmp, p);
   } catch (err) {
diff --git a/tests/broken-windows.test.cjs b/tests/broken-windows.test.cjs
index 00edad0b4..6e07b794f 100644
--- a/tests/broken-windows.test.cjs
+++ b/tests/broken-windows.test.cjs
@@ -603,6 +603,66 @@ describe('broken-windows CLI: windows append', () => {
     assert.equal(res.success, false);
     assert.match(res.error, /4-backtick|fence|invalid_text/i);
   });
+
+  // ─── #2893: append must not destroy prose below the JSON ledger ──────────
+
+  test('#2893 — append preserves prose below the JSON ledger block', (t) => {
+    const tmp = createTempDir('bw-append-prose-');
+    t.after(() => cleanup(tmp));
+
+    // Create a WINDOWS.md with a NON-EMPTY ledger + prose below the JSON block.
+    fs.mkdirSync(path.join(tmp, '.planning'), { recursive: true });
+    const lp = path.join(tmp, '.planning', LEDGER_FILE_NAME);
+    const initial = renderLedger({
+      schema_version: 1, open_count: 1, waived_count: 0, fixed_count: 0, total_count: 1,
+      last_updated: '2026-01-01T00:00:00Z',
+      entries: [{ id: 1, phase: '1', kind: 'stub', file: '', line: null, description: 'pre-existing', status: 'open', reason: '', recorded_at: '2026-01-01T00:00:00Z', resolved_at: null }],
+    });
+    const prose = [
+      '',
+      '## Investigation Notes',
+      '',
+      'This window was opened because the flaky test in thread-status.test.ts',
+      'turned out to be a real race condition against live data, not a pre-existing break.',
+      '',
+      '## ACPT-M03',
+      '',
+      'Went red on a green that PREDATED the diff — checkpoint refused, then fixed.',
+    ].join('\n');
+    fs.writeFileSync(lp, initial + prose, 'utf8');
+
+    // First append.
+    const res = runGsdTools(
+      ['windows', 'append', '--kind', 'stub', '--phase', '2', '--description', 'test entry'],
+      tmp,
+    );
+    assert.equal(res.success, true, `stderr: ${res.error || ''}`);
+    assert.equal(JSON.parse(res.output).ok, true);
+
+    // Second append — idempotency: prose must appear exactly once, not duplicated.
+    const res2 = runGsdTools(
+      ['windows', 'append', '--kind', 'todo', '--phase', '3', '--description', 'second entry'],
+      tmp,
+    );
+    assert.equal(res2.success, true);
+
+    const after = fs.readFileSync(lp, 'utf8');
+    // Prose must survive.
+    assert.match(after, /Investigation Notes/, 'prose heading must survive');
+    assert.match(after, /thread-status\.test\.ts/, 'prose body must survive');
+    assert.match(after, /ACPT-M03/, 'second prose heading must survive');
+    assert.match(after, /PREDATED the diff/, 'second prose body must survive');
+    // Prose must appear exactly once (not duplicated by the second write).
+    assert.equal((after.match(/Investigation Notes/g) || []).length, 1,
+      'prose heading must appear exactly once after two appends (idempotency)');
+    // The old JSON body must NOT be duplicated as prose (the indexOf(open-fence) bug).
+    // Count JSON fence opens — there must be exactly one.
+    assert.equal((after.match(/````json/g) || []).length, 1,
+      'exactly one JSON fence open must exist (no duplicated JSON body)');
+    // The file must re-parse cleanly with the correct entry count.
+    const reParsed = parseLedger(after);
+    assert.equal(reParsed.entries.length, 3, 'ledger must have 3 entries after two appends');
+  });
 });
 
 // ---------------------------------------------------------------------------