diff --git a/.agents/skills/impeccable/scripts/hook-lib.mjs b/.agents/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.agents/skills/impeccable/scripts/hook-lib.mjs
+++ b/.agents/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.agents/skills/impeccable/scripts/lib/is-generated.mjs b/.agents/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.agents/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.agents/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.agents/skills/impeccable/scripts/lib/staleness-deep.mjs b/.agents/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.agents/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.agents/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.agents/skills/impeccable/scripts/live.mjs b/.agents/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.agents/skills/impeccable/scripts/live.mjs
+++ b/.agents/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.claude/skills/impeccable/scripts/hook-lib.mjs b/.claude/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.claude/skills/impeccable/scripts/hook-lib.mjs
+++ b/.claude/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.claude/skills/impeccable/scripts/lib/is-generated.mjs b/.claude/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.claude/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.claude/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.claude/skills/impeccable/scripts/lib/staleness-deep.mjs b/.claude/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.claude/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.claude/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.claude/skills/impeccable/scripts/live.mjs b/.claude/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.claude/skills/impeccable/scripts/live.mjs
+++ b/.claude/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.cursor/skills/impeccable/scripts/hook-lib.mjs b/.cursor/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.cursor/skills/impeccable/scripts/hook-lib.mjs
+++ b/.cursor/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.cursor/skills/impeccable/scripts/lib/is-generated.mjs b/.cursor/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.cursor/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.cursor/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.cursor/skills/impeccable/scripts/lib/staleness-deep.mjs b/.cursor/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.cursor/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.cursor/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.cursor/skills/impeccable/scripts/live.mjs b/.cursor/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.cursor/skills/impeccable/scripts/live.mjs
+++ b/.cursor/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.gemini/skills/impeccable/scripts/hook-lib.mjs b/.gemini/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.gemini/skills/impeccable/scripts/hook-lib.mjs
+++ b/.gemini/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.gemini/skills/impeccable/scripts/lib/is-generated.mjs b/.gemini/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.gemini/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.gemini/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.gemini/skills/impeccable/scripts/lib/staleness-deep.mjs b/.gemini/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.gemini/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.gemini/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.gemini/skills/impeccable/scripts/live.mjs b/.gemini/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.gemini/skills/impeccable/scripts/live.mjs
+++ b/.gemini/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.github/skills/impeccable/scripts/hook-lib.mjs b/.github/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.github/skills/impeccable/scripts/hook-lib.mjs
+++ b/.github/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.github/skills/impeccable/scripts/lib/is-generated.mjs b/.github/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.github/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.github/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.github/skills/impeccable/scripts/lib/staleness-deep.mjs b/.github/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.github/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.github/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.github/skills/impeccable/scripts/live.mjs b/.github/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.github/skills/impeccable/scripts/live.mjs
+++ b/.github/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.grok/skills/impeccable/scripts/hook-lib.mjs b/.grok/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.grok/skills/impeccable/scripts/hook-lib.mjs
+++ b/.grok/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.grok/skills/impeccable/scripts/lib/is-generated.mjs b/.grok/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.grok/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.grok/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.grok/skills/impeccable/scripts/lib/staleness-deep.mjs b/.grok/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.grok/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.grok/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.grok/skills/impeccable/scripts/live.mjs b/.grok/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.grok/skills/impeccable/scripts/live.mjs
+++ b/.grok/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.kiro/skills/impeccable/scripts/hook-lib.mjs b/.kiro/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.kiro/skills/impeccable/scripts/hook-lib.mjs
+++ b/.kiro/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.kiro/skills/impeccable/scripts/lib/is-generated.mjs b/.kiro/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.kiro/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.kiro/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.kiro/skills/impeccable/scripts/lib/staleness-deep.mjs b/.kiro/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.kiro/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.kiro/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.kiro/skills/impeccable/scripts/live.mjs b/.kiro/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.kiro/skills/impeccable/scripts/live.mjs
+++ b/.kiro/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.opencode/skills/impeccable/scripts/hook-lib.mjs b/.opencode/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.opencode/skills/impeccable/scripts/hook-lib.mjs
+++ b/.opencode/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.opencode/skills/impeccable/scripts/lib/is-generated.mjs b/.opencode/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.opencode/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.opencode/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.opencode/skills/impeccable/scripts/lib/staleness-deep.mjs b/.opencode/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.opencode/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.opencode/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.opencode/skills/impeccable/scripts/live.mjs b/.opencode/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.opencode/skills/impeccable/scripts/live.mjs
+++ b/.opencode/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.pi/skills/impeccable/scripts/hook-lib.mjs b/.pi/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.pi/skills/impeccable/scripts/hook-lib.mjs
+++ b/.pi/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.pi/skills/impeccable/scripts/lib/is-generated.mjs b/.pi/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.pi/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.pi/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.pi/skills/impeccable/scripts/lib/staleness-deep.mjs b/.pi/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.pi/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.pi/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.pi/skills/impeccable/scripts/live.mjs b/.pi/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.pi/skills/impeccable/scripts/live.mjs
+++ b/.pi/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.qoder/skills/impeccable/scripts/hook-lib.mjs b/.qoder/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.qoder/skills/impeccable/scripts/hook-lib.mjs
+++ b/.qoder/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.qoder/skills/impeccable/scripts/lib/is-generated.mjs b/.qoder/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.qoder/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.qoder/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.qoder/skills/impeccable/scripts/lib/staleness-deep.mjs b/.qoder/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.qoder/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.qoder/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.qoder/skills/impeccable/scripts/live.mjs b/.qoder/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.qoder/skills/impeccable/scripts/live.mjs
+++ b/.qoder/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.rovodev/skills/impeccable/scripts/hook-lib.mjs b/.rovodev/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.rovodev/skills/impeccable/scripts/hook-lib.mjs
+++ b/.rovodev/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.rovodev/skills/impeccable/scripts/lib/is-generated.mjs b/.rovodev/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.rovodev/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.rovodev/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.rovodev/skills/impeccable/scripts/lib/staleness-deep.mjs b/.rovodev/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.rovodev/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.rovodev/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.rovodev/skills/impeccable/scripts/live.mjs b/.rovodev/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.rovodev/skills/impeccable/scripts/live.mjs
+++ b/.rovodev/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.trae-cn/skills/impeccable/scripts/hook-lib.mjs b/.trae-cn/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.trae-cn/skills/impeccable/scripts/hook-lib.mjs
+++ b/.trae-cn/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.trae-cn/skills/impeccable/scripts/lib/is-generated.mjs b/.trae-cn/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.trae-cn/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.trae-cn/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.trae-cn/skills/impeccable/scripts/lib/staleness-deep.mjs b/.trae-cn/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.trae-cn/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.trae-cn/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.trae-cn/skills/impeccable/scripts/live.mjs b/.trae-cn/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.trae-cn/skills/impeccable/scripts/live.mjs
+++ b/.trae-cn/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.trae/skills/impeccable/scripts/hook-lib.mjs b/.trae/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.trae/skills/impeccable/scripts/hook-lib.mjs
+++ b/.trae/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.trae/skills/impeccable/scripts/lib/is-generated.mjs b/.trae/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.trae/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.trae/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.trae/skills/impeccable/scripts/lib/staleness-deep.mjs b/.trae/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.trae/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.trae/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.trae/skills/impeccable/scripts/live.mjs b/.trae/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.trae/skills/impeccable/scripts/live.mjs
+++ b/.trae/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/.vibe/skills/impeccable/scripts/hook-lib.mjs b/.vibe/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/.vibe/skills/impeccable/scripts/hook-lib.mjs
+++ b/.vibe/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/.vibe/skills/impeccable/scripts/lib/is-generated.mjs b/.vibe/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/.vibe/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/.vibe/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/.vibe/skills/impeccable/scripts/lib/staleness-deep.mjs b/.vibe/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/.vibe/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/.vibe/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/.vibe/skills/impeccable/scripts/live.mjs b/.vibe/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/.vibe/skills/impeccable/scripts/live.mjs
+++ b/.vibe/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }
diff --git a/plugin/skills/impeccable/scripts/hook-lib.mjs b/plugin/skills/impeccable/scripts/hook-lib.mjs
index b874985a6..9170aa696 100644
--- a/plugin/skills/impeccable/scripts/hook-lib.mjs
+++ b/plugin/skills/impeccable/scripts/hook-lib.mjs
@@ -1112,7 +1112,19 @@ function formatFindingIgnoreCommand(finding) {
 function quoteCommandArg(value) {
   const text = String(value || '').trim();
   if (/^[A-Za-z0-9._:-]+$/.test(text)) return text;
-  return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  // The suggestion is meant to be run on this same machine, so quote for its
+  // shell. POSIX /bin/sh still expands $(...), backticks, and ${} inside
+  // double quotes, and these values come from scanned file content (a
+  // font-family name) or a file path, so untrusted input must be
+  // single-quoted (issue #476). Windows cmd.exe performs no such command
+  // substitution, but it treats a single quote as a literal character rather
+  // than a grouping delimiter, so a value or path containing spaces has to
+  // stay double-quoted there (Greptile #533). Keep the pre-existing
+  // double-quote escaping on Windows so that path's behavior is unchanged.
+  if (process.platform === 'win32') {
+    return `"${text.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`;
+  }
+  return `'${text.replace(/'/g, `'\\''`)}'`;
 }
 
 function relativize(filePath, cwd) {
diff --git a/plugin/skills/impeccable/scripts/lib/is-generated.mjs b/plugin/skills/impeccable/scripts/lib/is-generated.mjs
index 165e1ca80..5e5948ad8 100644
--- a/plugin/skills/impeccable/scripts/lib/is-generated.mjs
+++ b/plugin/skills/impeccable/scripts/lib/is-generated.mjs
@@ -13,7 +13,7 @@
  *      within the first ~300 characters — catches non-git projects.
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 
@@ -41,7 +41,10 @@ export function isGeneratedFile(filePath, options = {}) {
 
 function isGitIgnored(absPath, cwd) {
   try {
-    execSync(`git check-ignore --quiet ${JSON.stringify(absPath)}`, {
+    // argv form, never a shell: this runs on every file the live-mode source
+    // walk reaches, so a hostile filename embedding $(...) or backticks must
+    // not be interpretable (issue #476). JSON.stringify is not shell quoting.
+    execFileSync('git', ['check-ignore', '--quiet', absPath], {
       cwd,
       stdio: 'ignore',
     });
diff --git a/plugin/skills/impeccable/scripts/lib/staleness-deep.mjs b/plugin/skills/impeccable/scripts/lib/staleness-deep.mjs
index 2c8d6a82f..f3ce76d9f 100644
--- a/plugin/skills/impeccable/scripts/lib/staleness-deep.mjs
+++ b/plugin/skills/impeccable/scripts/lib/staleness-deep.mjs
@@ -244,7 +244,8 @@ const HOOK_MARKER = /skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs/;
 //   * bundle-relative: node ".agents/.../hook.mjs"
 //   * legacy unquoted: node .claude/.../hook.mjs
 //   * guarded (#399):  [ ! -f "PATH" ] || node "PATH"   (PATH twice, identical)
-//   * absolute:        node "/Users/.../hook.mjs"        (user-level installs)
+//   * absolute (#476): [ ! -f 'PATH' ] || node 'PATH'   (single-quoted since
+//                      the shell-injection fix; older installs double-quote)
 //   * github portable: node "$(git rev-parse --show-toplevel)/.../hook.mjs"
 // A quoted path wins; the guard's two occurrences are identical, so the first
 // quoted match is the path. Otherwise fall back to the whitespace/metachar-
@@ -255,6 +256,12 @@ function hookScriptTokenFrom(command) {
   if (!HOOK_MARKER.test(str)) return null;
   const quoted = str.match(/"([^"]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)"/);
   if (quoted) return quoted[1];
+  // A path containing an apostrophe serializes as '\'' inside single quotes;
+  // no regex reassembles that, and the bare fallback would misread a fragment
+  // of it, so return null: the caller never asserts on a path it can't parse.
+  if (str.includes("'\\''")) return null;
+  const singleQuoted = str.match(/'([^']*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)'/);
+  if (singleQuoted) return singleQuoted[1];
   const bare = str.match(/([^\s"'|&;()]*skills\/impeccable\/scripts\/hook(?:-before-edit)?\.mjs)/);
   return bare ? bare[1] : null;
 }
diff --git a/plugin/skills/impeccable/scripts/live.mjs b/plugin/skills/impeccable/scripts/live.mjs
index b04d98f50..7738c3f02 100644
--- a/plugin/skills/impeccable/scripts/live.mjs
+++ b/plugin/skills/impeccable/scripts/live.mjs
@@ -17,7 +17,7 @@
  *   node live.mjs --help
  */
 
-import { execSync } from 'node:child_process';
+import { execFileSync } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -316,11 +316,17 @@ function globToRegex(pattern) {
 
 function runScript(name, args, options = {}) {
   const scriptPath = path.join(__dirname, name);
-  const cmd = `node "${scriptPath}" ${args.map(a => `"${a}"`).join(' ')}`;
   try {
-    return execSync(cmd, { encoding: 'utf-8', cwd: options.cwd || process.cwd(), timeout: 15_000 });
+    // argv form, never a shell: string interpolation into double quotes would
+    // let a `"` or `$(...)` in any future caller's arg escape into the shell
+    // (issue #476).
+    return execFileSync(process.execPath, [scriptPath, ...args], {
+      encoding: 'utf-8',
+      cwd: options.cwd || process.cwd(),
+      timeout: 15_000,
+    });
   } catch (err) {
-    // execSync throws on non-zero exit; return stdout if any
+    // execFileSync throws on non-zero exit; return stdout if any
     return err.stdout || err.message || '';
   }
 }