diff --git a/site/src/content/docs/reference/cli.md b/site/src/content/docs/reference/cli.md
index 0ac1f15..4957059 100644
--- a/site/src/content/docs/reference/cli.md
+++ b/site/src/content/docs/reference/cli.md
@@ -29,6 +29,22 @@ global link.
 | `--json` | Machine-readable reports for ingest, refine, review, build, query, check, and eval. `init` retains its text message; MCP uses its stdio protocol rather than a CLI JSON report. |
 | `--help` | Usage for the CLI or for a single command |
 
+### Human output and machine data
+
+The `init` root, `ingest` result path, finding strings in the human-readable
+`check` and `eval` reports, and `check` configuration errors on stderr use inert
+single-line rendering. Terminal controls, C1 controls, bidirectional controls,
+and Unicode line separators become visible escapes such as `\u001b`, `\u009b`,
+and `\u202e`; line endings become `\n`.
+Ordinary text and literal backslashes are unchanged. This is display hardening,
+not Markdown sanitization, a filesystem rename, or an admission decision.
+
+This human-output escaping does not alter machine report values. The
+`safeJsonStringify` helper used by some JSON outputs escapes the serialized text
+without changing decoded values: `JSON.parse` still recovers the original controls,
+line endings, quotes, and backslashes. Consumers must render decoded strings
+inertly themselves rather than treating machine JSON as sanitized content.
+
 ## What each command may write
 
 | Command | Writes | Cannot write |
diff --git a/src/cli/commands/check.ts b/src/cli/commands/check.ts
index 242a527..c276a65 100644
--- a/src/cli/commands/check.ts
+++ b/src/cli/commands/check.ts
@@ -6,6 +6,7 @@ import type { CliIO } from '../main.js';
 import { GENERATED_ARTIFACTS, auditCleanRoom } from '../../eval/clean-room.js';
 import type { CleanRoomReport } from '../../eval/clean-room.js';
 import { renderCleanRoomMarkdown } from '../../eval/report.js';
+import { inertSingleLineText } from '../../presentation/inert.js';
 
 /**
  * Directories that never contain authored content. Everything else in the repository is
@@ -230,7 +231,7 @@ export async function runCheck(root: string, json: boolean, io: CliIO): Promise<
     } else {
       io.stdout(renderCleanRoomMarkdown(failure) + '\n');
     }
-    io.stderr(`error: ${err.message}\n`);
+    io.stderr(`error: ${inertSingleLineText(err.message)}\n`);
     return 1;
   }
 
diff --git a/src/cli/commands/ingest.ts b/src/cli/commands/ingest.ts
index 6d40c94..eedd05d 100644
--- a/src/cli/commands/ingest.ts
+++ b/src/cli/commands/ingest.ts
@@ -1,5 +1,6 @@
 import type { CliIO } from '../main.js';
 import { ingestCapture } from '../../bronze/ingest.js';
+import { inertSingleLineText } from '../../presentation/inert.js';
 
 export async function runIngest(root: string, file: string | undefined, json: boolean, io: CliIO): Promise<number> {
   if (!file) {
@@ -10,7 +11,7 @@ export async function runIngest(root: string, file: string | undefined, json: bo
   if (json) {
     io.stdout(JSON.stringify(result, null, 2) + '\n');
   } else {
-    io.stdout(`${result.status}: ${result.source_path}\n`);
+    io.stdout(`${result.status}: ${inertSingleLineText(result.source_path)}\n`);
   }
   return 0;
 }
diff --git a/src/cli/commands/init.ts b/src/cli/commands/init.ts
index b799f0a..8b2cb54 100644
--- a/src/cli/commands/init.ts
+++ b/src/cli/commands/init.ts
@@ -1,6 +1,7 @@
 import { mkdir, writeFile } from 'node:fs/promises';
 import { join } from 'node:path';
 import type { CliIO } from '../main.js';
+import { inertSingleLineText } from '../../presentation/inert.js';
 
 const STARTER_DIRS = [
   'bronze',
@@ -51,6 +52,6 @@ export async function runInit(root: string, io: CliIO): Promise<number> {
     }
   }
 
-  io.stdout(`Initialized Ziggurat vault at ${root}\n`);
+  io.stdout(`Initialized Ziggurat vault at ${inertSingleLineText(root)}\n`);
   return 0;
 }
diff --git a/src/eval/report.ts b/src/eval/report.ts
index 86d7a69..c3bbfca 100644
--- a/src/eval/report.ts
+++ b/src/eval/report.ts
@@ -1,5 +1,6 @@
 import type { ConformanceReport } from './conformance.js';
 import type { CleanRoomReport } from './clean-room.js';
+import { inertSingleLineText } from '../presentation/inert.js';
 
 /** Renders a ConformanceReport as Markdown. */
 export function renderConformanceMarkdown(report: ConformanceReport): string {
@@ -13,7 +14,7 @@ export function renderConformanceMarkdown(report: ConformanceReport): string {
 
   for (const f of report.findings) {
     const icon = f.passed ? '✓' : '✗';
-    lines.push(`${icon} ${f.case_id}: ${f.detail}`);
+    lines.push(`${icon} ${inertSingleLineText(f.case_id)}: ${inertSingleLineText(f.detail)}`);
   }
 
   return lines.join('\n');
@@ -31,7 +32,7 @@ export function renderCleanRoomMarkdown(report: CleanRoomReport): string {
     lines.push('No findings.');
   } else {
     for (const f of report.findings) {
-      lines.push(`- ${f.path}:${f.line} [${f.category}] ${f.detail}`);
+      lines.push(`- ${inertSingleLineText(f.path)}:${f.line} [${inertSingleLineText(f.category)}] ${inertSingleLineText(f.detail)}`);
     }
   }
 
diff --git a/test/cli-inert-output.test.ts b/test/cli-inert-output.test.ts
new file mode 100644
index 0000000..64abbf4
--- /dev/null
+++ b/test/cli-inert-output.test.ts
@@ -0,0 +1,238 @@
+import assert from 'node:assert/strict';
+import { mkdir, mkdtemp, readFile, readdir, rename, rm, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import test from 'node:test';
+import { runCli, type CliIO } from '../src/cli/main.js';
+import type { CleanRoomReport } from '../src/eval/clean-room.js';
+import type { ConformanceReport } from '../src/eval/conformance.js';
+import { renderCleanRoomMarkdown, renderConformanceMarkdown } from '../src/eval/report.js';
+import { safeJsonStringify } from '../src/presentation/inert.js';
+
+const LIVE_CONTROLS =
+  /[\x00-\x09\x0b-\x1f\x7f-\x9f\u061c\u200e\u200f\u2028\u2029\u202a-\u202e\u2066-\u2069]/u;
+const HOSTILE = 'before\\literal\\u009b"\u0000\t\u001b[2J\u007f\u0085\u009b31m\u202e\u2066\r\nnext\rlast\nend';
+const INERT = 'before\\literal\\u009b"\\u0000\\u0009\\u001b[2J\\u007f\\u0085\\u009b31m\\u202e\\u2066\\nnext\\nlast\\nend';
+
+// C1, bidi, and Unicode line separators are permitted in Windows filenames too.
+const HOSTILE_NAME = 'note-\u009b31m\u202e\u2028.md';
+const INERT_NAME = 'note-\\u009b31m\\u202e\\u2028.md';
+
+function captureIO(): { io: CliIO; captured: { out: string; err: string } } {
+  const captured = { out: '', err: '' };
+  return {
+    captured,
+    io: {
+      stdout: text => { captured.out += text; },
+      stderr: text => { captured.err += text; },
+    },
+  };
+}
+
+test('clean-room Markdown renders every finding string as inert single-line text', () => {
+  const report: CleanRoomReport = {
+    pass: false,
+    findings: [{ path: HOSTILE, line: 7, category: HOSTILE, detail: HOSTILE }],
+  };
+  const before = structuredClone(report);
+  const rendered = renderCleanRoomMarkdown(report);
+
+  assert.equal(rendered, `# Clean-Room Audit: FAIL\n\n- ${INERT}:7 [${INERT}] ${INERT}`);
+  assert.doesNotMatch(rendered, LIVE_CONTROLS);
+  assert.deepEqual(report, before);
+});
+
+test('conformance Markdown renders case IDs and details as inert single-line text', () => {
+  const report: ConformanceReport = {
+    pass: false,
+    cases_run: 2,
+    passed: 1,
+    failed: 1,
+    findings: [
+      { case_id: HOSTILE, passed: true, detail: HOSTILE },
+      { case_id: HOSTILE, passed: false, detail: HOSTILE },
+    ],
+  };
+  const before = structuredClone(report);
+  const rendered = renderConformanceMarkdown(report);
+
+  assert.equal(
+    rendered,
+    '# Conformance Report: FAIL\n\nCases: 2 | Passed: 1 | Failed: 1\n\n'
+      + `\u2713 ${INERT}: ${INERT}\n\u2717 ${INERT}: ${INERT}`,
+  );
+  assert.doesNotMatch(rendered, LIVE_CONTROLS);
+  assert.deepEqual(report, before);
+});
+
+test('report renderers preserve ordinary wording, punctuation, and backslashes', () => {
+  assert.equal(
+    renderCleanRoomMarkdown({ pass: true, findings: [] }),
+    '# Clean-Room Audit: PASS\n\nNo findings.',
+  );
+  assert.equal(
+    renderCleanRoomMarkdown({
+      pass: false,
+      findings: [{ path: 'notes\\example.md', line: 3, category: 'example', detail: 'Review this file.' }],
+    }),
+    '# Clean-Room Audit: FAIL\n\n- notes\\example.md:3 [example] Review this file.',
+  );
+  assert.equal(
+    renderConformanceMarkdown({
+      pass: true,
+      cases_run: 1,
+      passed: 1,
+      failed: 0,
+      findings: [{ case_id: 'C001', passed: true, detail: 'Passed correctly.' }],
+    }),
+    '# Conformance Report: PASS\n\nCases: 1 | Passed: 1 | Failed: 0\n\n\u2713 C001: Passed correctly.',
+  );
+});
+
+test('safe JSON remains render-safe and byte-exact after parsing, including literal escapes', () => {
+  const value = {
+    path: HOSTILE,
+    body: `${HOSTILE}\n\\n\\r\\u202e\\\\end`,
+    detail: '\u061c\u200e\u200f\u2028\u2029\u202a\u202b\u202c\u202d\u202e\u2066\u2067\u2068\u2069',
+  };
+  for (const space of [undefined, 2]) {
+    const rendered = safeJsonStringify(value, space);
+    const decoded = JSON.parse(rendered) as typeof value;
+    assert.doesNotMatch(rendered, LIVE_CONTROLS);
+    assert.deepEqual(decoded, JSON.parse(JSON.stringify(value)));
+    for (const field of ['path', 'body', 'detail'] as const) {
+      assert.deepEqual(Buffer.from(decoded[field], 'utf8'), Buffer.from(value[field], 'utf8'));
+    }
+  }
+});
+
+test('init CLI renders real hostile roots inertly without changing the initialized path', async () => {
+  const base = await mkdtemp(join(tmpdir(), 'ziggurat-inert-init-'));
+  const root = join(base, 'vault-\u009b31m\u202e\u2028');
+  try {
+    for (let attempt = 0; attempt < 2; attempt++) {
+      const { io, captured } = captureIO();
+      assert.equal(await runCli(['init', '--root', root], io), 0);
+      assert.equal(captured.out, `Initialized Ziggurat vault at ${join(base, 'vault-\\u009b31m\\u202e\\u2028')}\n`);
+      assert.doesNotMatch(captured.out, LIVE_CONTROLS);
+      assert.equal(captured.err, '');
+    }
+    assert.match(await readFile(join(root, 'config', 'ziggurat.yaml'), 'utf8'), /^schema_version: 1\n/u);
+  } finally {
+    await rm(base, { recursive: true, force: true });
+  }
+});
+
+test('ingest CLI renders duplicate Bronze paths inertly while machine JSON retains exact filenames', async () => {
+  const root = await mkdtemp(join(tmpdir(), 'ziggurat-inert-ingest-'));
+  const body = 'An ordinary captured note.\n';
+  const inboxPath = join(root, 'inbox', 'note.md');
+  try {
+    const initialized = captureIO();
+    assert.equal(await runCli(['init', '--root', root], initialized.io), 0);
+    assert.equal(initialized.captured.out, `Initialized Ziggurat vault at ${root}\n`);
+    assert.equal(initialized.captured.err, '');
+    await writeFile(inboxPath, body, 'utf8');
+    const created = captureIO();
+    assert.equal(await runCli(['ingest', '--root', root, '--file', 'inbox/note.md'], created.io), 0);
+    const bronzeDir = join(root, 'bronze', 'article');
+    const files = await readdir(bronzeDir);
+    assert.equal(files.length, 1);
+    const filename = files[0];
+    assert.ok(filename !== undefined);
+    assert.equal(created.captured.out, `created: bronze/article/${filename}\n`);
+    assert.equal(created.captured.err, '');
+
+    // New ingest paths are slugified; duplicate lookup returns existing Bronze names.
+    await rename(join(bronzeDir, filename), join(bronzeDir, HOSTILE_NAME));
+    await writeFile(inboxPath, body, 'utf8');
+    const human = captureIO();
+    assert.equal(await runCli(['ingest', '--root', root, '--file', 'inbox/note.md'], human.io), 0);
+    assert.equal(human.captured.out, `duplicate: bronze/article/${INERT_NAME}\n`);
+    assert.doesNotMatch(human.captured.out, LIVE_CONTROLS);
+    assert.equal(human.captured.err, '');
+
+    const machine = captureIO();
+    assert.equal(await runCli(['ingest', '--root', root, '--file', 'inbox/note.md', '--json'], machine.io), 0);
+    const result = JSON.parse(machine.captured.out) as { status: string; source_path: string };
+    assert.equal(result.status, 'duplicate');
+    assert.deepEqual(Buffer.from(result.source_path, 'utf8'), Buffer.from(`bronze/article/${HOSTILE_NAME}`, 'utf8'));
+    assert.equal(machine.captured.err, '');
+    assert.equal(await readFile(inboxPath, 'utf8'), body);
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('check CLI renders real finding paths and details inertly while JSON retains their exact values', async () => {
+  const root = await mkdtemp(join(tmpdir(), 'ziggurat-inert-check-'));
+  try {
+    await writeFile(join(root, HOSTILE_NAME), Buffer.from([0xff]));
+    const human = captureIO();
+    assert.equal(await runCli(['check', '--root', root, '--audit-clean-room'], human.io), 1);
+    assert.equal(
+      human.captured.out,
+      '# Clean-Room Audit: FAIL\n\n'
+        + `- ${INERT_NAME}:0 [unscannable-file] File is not valid UTF-8 text. `
+        + `Review it and add an explicit clean-room exclusion if it is safe: ${INERT_NAME}\n`,
+    );
+    assert.doesNotMatch(human.captured.out, LIVE_CONTROLS);
+    assert.equal(human.captured.err, '');
+
+    const machine = captureIO();
+    assert.equal(await runCli(['check', '--root', root, '--audit-clean-room', '--json'], machine.io), 1);
+    const report = JSON.parse(machine.captured.out) as CleanRoomReport;
+    assert.deepEqual(report, {
+      pass: false,
+      findings: [{
+        path: HOSTILE_NAME,
+        category: 'unscannable-file',
+        line: 0,
+        detail: 'File is not valid UTF-8 text. Review it and add an explicit clean-room exclusion if it is safe: '
+          + HOSTILE_NAME,
+      }],
+    });
+    assert.equal(machine.captured.err, '');
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});
+
+test('check CLI renders unknown config keys inertly on stderr without changing JSON diagnostics', async () => {
+  const root = await mkdtemp(join(tmpdir(), 'ziggurat-inert-config-'));
+  const prefix = 'config/clean-room.yaml: unknown configuration keys: ';
+  const suffix = '. Allowed keys are exclude_paths and project_names.';
+  const inertDetail = `${prefix}${INERT}${suffix}`;
+  try {
+    await mkdir(join(root, 'config'));
+    await writeFile(join(root, 'config', 'clean-room.yaml'), `${JSON.stringify(HOSTILE)}: true\n`, 'utf8');
+    for (const json of [false, true]) {
+      const { io, captured } = captureIO();
+      const args = ['check', '--root', root, '--audit-clean-room', ...(json ? ['--json'] : [])];
+      assert.equal(await runCli(args, io), 1);
+      assert.equal(captured.err, `error: ${inertDetail}\n`);
+      assert.doesNotMatch(captured.err, LIVE_CONTROLS);
+      if (json) {
+        const report = JSON.parse(captured.out) as CleanRoomReport;
+        assert.deepEqual(report, {
+          pass: false,
+          findings: [{
+            path: 'config/clean-room.yaml',
+            category: 'invalid-clean-room-config',
+            line: 0,
+            detail: `${prefix}${HOSTILE}${suffix}`,
+          }],
+        });
+      } else {
+        assert.equal(
+          captured.out,
+          '# Clean-Room Audit: FAIL\n\n'
+            + `- config/clean-room.yaml:0 [invalid-clean-room-config] ${inertDetail}\n`,
+        );
+        assert.doesNotMatch(captured.out, LIVE_CONTROLS);
+      }
+    }
+  } finally {
+    await rm(root, { recursive: true, force: true });
+  }
+});