diff --git a/features/diagnostic.mjs b/features/diagnostic.mjs
new file mode 100644
index 0000000..8c6e1ef
--- /dev/null
+++ b/features/diagnostic.mjs
@@ -0,0 +1,167 @@
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { execSync } from 'node:child_process';
+import os from 'node:os';
+import process from 'node:process';
+import dns from 'node:dns/promises';
+
+// Colors for output
+const RESET = '\x1b[0m';
+const RED = '\x1b[31m';
+const GREEN = '\x1b[32m';
+const YELLOW = '\x1b[33m';
+const BOLD = '\x1b[1m';
+
+let hasError = false;
+
+function log(msg) { console.log(msg); }
+function success(msg) { console.log(`${GREEN}✔ ${msg}${RESET}`); }
+function fail(msg) {
+  console.log(`${RED}✘ ${msg}${RESET}`);
+  hasError = true;
+}
+function warn(msg) { console.log(`${YELLOW}⚠ ${msg}${RESET}`); }
+function info(msg) { console.log(`  ${msg}`); }
+
+async function checkNodeVersion() {
+  log(`\n${BOLD}Checking Node.js Environment...${RESET}`);
+  const version = process.version;
+  const major = parseInt(version.slice(1).split('.')[0], 10);
+
+  if (major >= 22) {
+    success(`Node.js version: ${version}`);
+  } else {
+    fail(`Node.js version: ${version} (Expected >= 22.0.0)`);
+  }
+
+  info(`Platform: ${os.platform()} ${os.release()} (${os.arch()})`);
+  info(`Memory: ${Math.round(os.totalmem() / 1024 / 1024 / 1024)} GB Total`);
+}
+
+async function checkDependencies() {
+  log(`\n${BOLD}Checking Dependencies...${RESET}`);
+  const nodeModulesPath = path.resolve('node_modules');
+  try {
+    await fs.access(nodeModulesPath);
+    success('node_modules directory exists');
+  } catch {
+    fail('node_modules directory missing. Run "npm install".');
+    return;
+  }
+
+  try {
+    await import('nostr-tools');
+    success('nostr-tools loaded successfully');
+  } catch (e) {
+    fail(`Failed to load nostr-tools: ${e.message}`);
+  }
+
+  try {
+    await import('ws');
+    success('ws loaded successfully');
+  } catch (e) {
+    fail(`Failed to load ws: ${e.message}`);
+  }
+}
+
+async function checkConfiguration() {
+  log(`\n${BOLD}Checking Configuration...${RESET}`);
+  const configPath = path.resolve('torch-config.json');
+  try {
+    await fs.access(configPath);
+    success('torch-config.json exists');
+
+    // Validate content
+    const content = await fs.readFile(configPath, 'utf8');
+    const config = JSON.parse(content);
+
+    if (config.nostrLock && config.nostrLock.relays && Array.isArray(config.nostrLock.relays)) {
+      success(`Configuration valid. Found ${config.nostrLock.relays.length} relays.`);
+      info(`Namespace: ${config.nostrLock.namespace || 'default'}`);
+    } else {
+      fail('torch-config.json structure invalid (missing nostrLock.relays array)');
+    }
+  } catch (e) {
+    fail(`Configuration check failed: ${e.message}`);
+  }
+}
+
+async function checkFileSystem() {
+  log(`\n${BOLD}Checking File System...${RESET}`);
+  const dirs = [
+    'src',
+    'task-logs',
+    'src/prompts',
+    'src/prompts/daily',
+    'src/prompts/weekly'
+  ];
+
+  for (const dir of dirs) {
+    try {
+      await fs.access(path.resolve(dir));
+      success(`${dir} exists`);
+    } catch {
+      fail(`${dir} is missing`);
+    }
+  }
+
+  // Check write access to task-logs
+  const testFile = path.resolve('task-logs', '.diagnostic-write-test');
+  try {
+    await fs.writeFile(testFile, 'test');
+    await fs.unlink(testFile);
+    success('Write access to task-logs verified');
+  } catch (e) {
+    fail(`Write access to task-logs failed: ${e.message}`);
+  }
+}
+
+async function checkGit() {
+  log(`\n${BOLD}Checking Git...${RESET}`);
+  try {
+    execSync('git --version', { stdio: 'ignore' });
+    success('Git is installed');
+
+    try {
+      const branch = execSync('git rev-parse --abbrev-ref HEAD').toString().trim();
+      const commit = execSync('git rev-parse --short HEAD').toString().trim();
+      success(`Git repository valid (Branch: ${branch}, Commit: ${commit})`);
+    } catch {
+      warn('Not a git repository or no commits yet');
+    }
+  } catch {
+    fail('Git is not installed or not in PATH');
+  }
+}
+
+async function checkConnectivity() {
+  log(`\n${BOLD}Checking Connectivity...${RESET}`);
+  try {
+    await dns.lookup('google.com');
+    success('Internet connectivity verified (DNS lookup)');
+  } catch (e) {
+    fail(`Internet connectivity failed: ${e.message}`);
+  }
+}
+
+async function main() {
+  console.log(`${BOLD}TORCH Diagnostic Tool${RESET}`);
+  console.log('='.repeat(30));
+
+  await checkNodeVersion();
+  await checkDependencies();
+  await checkConfiguration();
+  await checkFileSystem();
+  await checkGit();
+  await checkConnectivity();
+
+  console.log('\n' + '='.repeat(30));
+  if (hasError) {
+    console.log(`${RED}Diagnostic failed with errors.${RESET}`);
+    process.exit(1);
+  } else {
+    console.log(`${GREEN}Diagnostic passed.${RESET}`);
+  }
+}
+
+main().catch(console.error);
diff --git a/src/context/CONTEXT_feature-proposer-agent-diagnostic.md b/src/context/CONTEXT_feature-proposer-agent-diagnostic.md
new file mode 100644
index 0000000..039cb6c
--- /dev/null
+++ b/src/context/CONTEXT_feature-proposer-agent-diagnostic.md
@@ -0,0 +1,13 @@
+# Context: Diagnostic Utility Script
+
+## Goal
+Create a standalone diagnostic utility to help users verify their local TORCH environment.
+
+## Scope
+- Implement `features/diagnostic.mjs`.
+- Checks for Node version, dependencies, config, file system, git, and connectivity.
+- No new dependencies.
+
+## Constraints
+- Single file implementation.
+- Must not modify existing files (except for adding the new feature).
diff --git a/src/decisions/DECISIONS_feature-proposer-agent-diagnostic.md b/src/decisions/DECISIONS_feature-proposer-agent-diagnostic.md
new file mode 100644
index 0000000..c2d6360
--- /dev/null
+++ b/src/decisions/DECISIONS_feature-proposer-agent-diagnostic.md
@@ -0,0 +1,12 @@
+# Decision: Implement Diagnostic Utility
+
+## Context
+New users or agents may struggle with setting up the environment correctly (Node version, missing config, etc.).
+
+## Decision
+Implemented `features/diagnostic.mjs` as a self-contained script to verify the environment.
+
+## Rationale
+- Low hanging fruit: high value for troubleshooting, low effort to implement.
+- Fits "New Utility Scripts" scope.
+- No external dependencies required beyond what's already in the project.
diff --git a/src/test_logs/TEST_LOG_feature-proposer-agent-diagnostic.md b/src/test_logs/TEST_LOG_feature-proposer-agent-diagnostic.md
new file mode 100644
index 0000000..5c245d0
--- /dev/null
+++ b/src/test_logs/TEST_LOG_feature-proposer-agent-diagnostic.md
@@ -0,0 +1,12 @@
+# Test Log: Diagnostic Utility
+
+## Manual Verification
+
+- Command: `node features/diagnostic.mjs`
+- Result: Passed (All checks green).
+
+- Command: `mv torch-config.json torch-config.json.bak && node features/diagnostic.mjs`
+- Result: Failed as expected (Exit code 1, missing config reported).
+
+- Command: `npm install && node features/diagnostic.mjs`
+- Result: Passed (Dependencies verified).
diff --git a/src/todo/TODO_feature-proposer-agent-diagnostic.md b/src/todo/TODO_feature-proposer-agent-diagnostic.md
new file mode 100644
index 0000000..68355cc
--- /dev/null
+++ b/src/todo/TODO_feature-proposer-agent-diagnostic.md
@@ -0,0 +1,7 @@
+# Pending Tasks
+- [x] Analyze codebase.
+- [x] Brainstorm features.
+- [x] Implement `features/diagnostic.mjs`.
+- [x] Verify implementation.
+- [x] Create run artifacts.
+- [ ] Submit changes.