diff --git a/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/.openspec.yaml b/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/.openspec.yaml
new file mode 100644
index 0000000..93831bd
--- /dev/null
+++ b/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-05-13
diff --git a/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/notes.md b/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/notes.md
new file mode 100644
index 0000000..5bcfd0e
--- /dev/null
+++ b/openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/notes.md
@@ -0,0 +1,16 @@
+# agent-claude-gx-budget-subcommand-2026-05-14-01-32 (minimal / T1)
+
+Branch: `agent/<your-name>/<branch-slug>`
+
+Describe the change in a sentence or two. Commit message is the spec of record.
+
+## Handoff
+
+- Handoff: change=`agent-claude-gx-budget-subcommand-2026-05-14-01-32`; branch=`agent/<your-name>/<branch-slug>`; scope=`TODO`; action=`continue this sandbox or finish cleanup after a usage-limit/manual takeover`.
+- Copy prompt: Continue `agent-claude-gx-budget-subcommand-2026-05-14-01-32` on branch `agent/<your-name>/<branch-slug>`. Work inside the existing sandbox, review `openspec/changes/agent-claude-gx-budget-subcommand-2026-05-14-01-32/notes.md`, continue from the current state instead of creating a new sandbox, and when the work is done run `gx branch finish --branch agent/<your-name>/<branch-slug> --base dev --via-pr --wait-for-merge --cleanup`.
+
+## Cleanup
+
+- [ ] Run: `gx branch finish --branch agent/<your-name>/<branch-slug> --base dev --via-pr --wait-for-merge --cleanup`
+- [ ] Record PR URL + `MERGED` state in the completion handoff.
+- [ ] Confirm sandbox worktree is gone (`git worktree list`, `git branch -a`).
diff --git a/src/budget/index.js b/src/budget/index.js
new file mode 100644
index 0000000..376d511
--- /dev/null
+++ b/src/budget/index.js
@@ -0,0 +1,343 @@
+'use strict';
+
+const cp = require('node:child_process');
+
+const TOOL_NAME = 'gx';
+
+const DEFAULT_WARN_NET_USD = 1; // any paid spend at all
+const DEFAULT_CRITICAL_NET_USD = 10; // paid spend that has caused merge blocks before
+
+function runGh(args) {
+  const result = cp.spawnSync('gh', args, { encoding: 'utf8' });
+  if (result.error) {
+    const err = new Error(`gh binary not found: ${result.error.message}`);
+    err.code = 'GH_BIN_MISSING';
+    throw err;
+  }
+  return result;
+}
+
+function ghApi(endpoint) {
+  const result = runGh(['api', endpoint]);
+  if (result.status !== 0) {
+    const message = (result.stderr || result.stdout || '').trim();
+    if (/404/.test(message)) {
+      const err = new Error(`GitHub API 404: ${endpoint}`);
+      err.code = 'GH_API_NOT_FOUND';
+      throw err;
+    }
+    if (/403/.test(message)) {
+      const err = new Error(
+        `GitHub API 403: ${endpoint}. The current token lacks the billing scope (org owners need admin:org; user accounts need user scope).`,
+      );
+      err.code = 'GH_API_FORBIDDEN';
+      throw err;
+    }
+    if (/410/.test(message)) {
+      const err = new Error(
+        `GitHub API 410: ${endpoint}. This endpoint was retired in early 2026; the new enhanced billing endpoint is /{scope}/{name}/settings/billing/usage.`,
+      );
+      err.code = 'GH_API_GONE';
+      throw err;
+    }
+    throw new Error(`gh api ${endpoint} failed: ${message}`);
+  }
+  try {
+    return JSON.parse(result.stdout);
+  } catch (parseErr) {
+    throw new Error(`gh api ${endpoint} returned non-JSON output: ${parseErr.message}`);
+  }
+}
+
+function detectCurrentLogin() {
+  const result = runGh(['api', 'user', '--jq', '.login']);
+  if (result.status !== 0) return null;
+  return result.stdout.trim() || null;
+}
+
+function fetchUsage({ org, user } = {}) {
+  if (org) {
+    const usage = ghApi(`/orgs/${org}/settings/billing/usage`);
+    return { scope: 'org', name: org, usage };
+  }
+  if (user) {
+    const usage = ghApi(`/users/${user}/settings/billing/usage`);
+    return { scope: 'user', name: user, usage };
+  }
+  const login = detectCurrentLogin();
+  if (!login) {
+    throw new Error(
+      `Could not detect the authenticated login. Pass --org <name> or --user <name> explicitly.`,
+    );
+  }
+  try {
+    const usage = ghApi(`/users/${login}/settings/billing/usage`);
+    return { scope: 'user', name: login, usage };
+  } catch (err) {
+    if (err.code === 'GH_API_NOT_FOUND') {
+      const usage = ghApi(`/orgs/${login}/settings/billing/usage`);
+      return { scope: 'org', name: login, usage };
+    }
+    throw err;
+  }
+}
+
+function currentMonthKey(now = new Date()) {
+  const year = now.getUTCFullYear();
+  const month = String(now.getUTCMonth() + 1).padStart(2, '0');
+  return `${year}-${month}`;
+}
+
+function itemMonthKey(item) {
+  // Dates land as 'YYYY-MM-01T00:00:00Z' for the start of a billed month.
+  return typeof item.date === 'string' ? item.date.slice(0, 7) : '';
+}
+
+function thresholdSeverity(netUsd, warnUsd, criticalUsd) {
+  if (netUsd >= criticalUsd) return 'critical';
+  if (netUsd >= warnUsd) return 'warn';
+  return 'ok';
+}
+
+function shapeBudgetReport({ scope, name, usage, monthKey, warnUsd, criticalUsd }) {
+  const items = Array.isArray(usage?.usageItems) ? usage.usageItems : [];
+  const targetMonth = monthKey ?? currentMonthKey();
+
+  const actionsThisMonth = items.filter(
+    (item) =>
+      item.product === 'actions' &&
+      item.unitType === 'Minutes' &&
+      itemMonthKey(item) === targetMonth,
+  );
+
+  const totalMinutes = actionsThisMonth.reduce((sum, item) => sum + (Number(item.quantity) || 0), 0);
+  const totalGross = actionsThisMonth.reduce(
+    (sum, item) => sum + (Number(item.grossAmount) || 0),
+    0,
+  );
+  const totalDiscount = actionsThisMonth.reduce(
+    (sum, item) => sum + (Number(item.discountAmount) || 0),
+    0,
+  );
+  const totalNet = actionsThisMonth.reduce((sum, item) => sum + (Number(item.netAmount) || 0), 0);
+
+  const byRepo = new Map();
+  const bySku = new Map();
+  for (const item of actionsThisMonth) {
+    const minutes = Number(item.quantity) || 0;
+    const repo = item.repositoryName || '(unknown)';
+    byRepo.set(repo, (byRepo.get(repo) || 0) + minutes);
+    const sku = item.sku || '(unknown)';
+    bySku.set(sku, (bySku.get(sku) || 0) + minutes);
+  }
+
+  const topRepos = [...byRepo.entries()]
+    .map(([repo, minutes]) => ({ repository: repo, minutes_used: round(minutes, 1) }))
+    .sort((a, b) => b.minutes_used - a.minutes_used)
+    .slice(0, 5);
+  const skuBreakdown = [...bySku.entries()]
+    .map(([sku, minutes]) => ({ sku, minutes_used: round(minutes, 1) }))
+    .sort((a, b) => b.minutes_used - a.minutes_used);
+
+  return {
+    scope,
+    name,
+    month: targetMonth,
+    actions_minutes_used: round(totalMinutes, 1),
+    gross_usd: round(totalGross, 2),
+    discount_usd: round(totalDiscount, 2),
+    net_usd: round(totalNet, 2),
+    severity: thresholdSeverity(totalNet, warnUsd, criticalUsd),
+    warn_threshold_usd: warnUsd,
+    critical_threshold_usd: criticalUsd,
+    top_repos: topRepos,
+    sku_breakdown: skuBreakdown,
+  };
+}
+
+function round(value, decimals) {
+  const factor = 10 ** decimals;
+  return Math.round(value * factor) / factor;
+}
+
+function formatBudgetReportText(report) {
+  const lines = [];
+  lines.push(
+    `${TOOL_NAME} budget — GitHub Actions usage for ${report.scope}:${report.name} (${report.month})`,
+  );
+  lines.push(`  actions minutes used: ${report.actions_minutes_used}`);
+  lines.push(
+    `  gross: $${report.gross_usd}   discount: $${report.discount_usd}   net (paid): $${report.net_usd}`,
+  );
+  if (report.sku_breakdown.length > 0) {
+    lines.push(`  by runner sku:`);
+    for (const entry of report.sku_breakdown) {
+      lines.push(`    ${entry.sku}: ${entry.minutes_used} min`);
+    }
+  }
+  if (report.top_repos.length > 0) {
+    lines.push(`  top repos:`);
+    for (const entry of report.top_repos) {
+      lines.push(`    ${entry.repository}: ${entry.minutes_used} min`);
+    }
+  }
+  const verdict =
+    report.severity === 'critical'
+      ? `CRITICAL — paid spend $${report.net_usd} this month is at/above $${report.critical_threshold_usd}. Raise the spending limit before the next push to avoid blocked merges.`
+      : report.severity === 'warn'
+        ? `WARN — paid spend $${report.net_usd} this month exceeds the warn threshold ($${report.warn_threshold_usd}). Review CI triggers or accept the spend.`
+        : `OK — no paid spend yet this month (all usage covered by free tier).`;
+  lines.push(`  status: ${verdict}`);
+  return lines.join('\n');
+}
+
+function parseBudgetArgs(rawArgs) {
+  const options = {
+    org: null,
+    user: null,
+    json: false,
+    help: false,
+    month: null,
+    warnUsd: DEFAULT_WARN_NET_USD,
+    criticalUsd: DEFAULT_CRITICAL_NET_USD,
+  };
+  const args = Array.isArray(rawArgs) ? [...rawArgs] : [];
+  while (args.length > 0) {
+    const arg = args.shift();
+    if (arg === '--help' || arg === '-h' || arg === 'help') {
+      options.help = true;
+      continue;
+    }
+    if (arg === '--json') {
+      options.json = true;
+      continue;
+    }
+    if (arg === '--org') {
+      options.org = args.shift();
+      continue;
+    }
+    if (arg === '--user') {
+      options.user = args.shift();
+      continue;
+    }
+    if (arg === '--month') {
+      options.month = args.shift();
+      continue;
+    }
+    if (arg === '--warn-usd') {
+      options.warnUsd = Number(args.shift());
+      continue;
+    }
+    if (arg === '--critical-usd') {
+      options.criticalUsd = Number(args.shift());
+      continue;
+    }
+    if (arg.startsWith('--org=')) {
+      options.org = arg.slice('--org='.length);
+      continue;
+    }
+    if (arg.startsWith('--user=')) {
+      options.user = arg.slice('--user='.length);
+      continue;
+    }
+    if (arg.startsWith('--month=')) {
+      options.month = arg.slice('--month='.length);
+      continue;
+    }
+    if (arg.startsWith('--warn-usd=')) {
+      options.warnUsd = Number(arg.slice('--warn-usd='.length));
+      continue;
+    }
+    if (arg.startsWith('--critical-usd=')) {
+      options.criticalUsd = Number(arg.slice('--critical-usd='.length));
+      continue;
+    }
+    const err = new Error(`Unknown budget argument: ${arg}`);
+    err.code = 'BUDGET_BAD_ARG';
+    throw err;
+  }
+  if (!Number.isFinite(options.warnUsd) || options.warnUsd < 0) {
+    throw new Error(`--warn-usd must be a non-negative number; got ${options.warnUsd}`);
+  }
+  if (!Number.isFinite(options.criticalUsd) || options.criticalUsd < 0) {
+    throw new Error(`--critical-usd must be a non-negative number; got ${options.criticalUsd}`);
+  }
+  return options;
+}
+
+function renderBudgetHelp() {
+  return [
+    `${TOOL_NAME} budget — GitHub Actions spend for the current month.`,
+    '',
+    'Usage:',
+    `  ${TOOL_NAME} budget [--org <name>] [--user <name>] [--month YYYY-MM] [--warn-usd <n>] [--critical-usd <n>] [--json]`,
+    '',
+    'Options:',
+    `  --org <name>          Query an org's billing (requires admin:org on the gh token).`,
+    `  --user <name>         Query a user's billing (requires user scope on the gh token).`,
+    `  --month YYYY-MM       Report a specific month (default: current UTC month).`,
+    `  --warn-usd <n>        Net-paid threshold to flag WARN (default ${DEFAULT_WARN_NET_USD}).`,
+    `  --critical-usd <n>    Net-paid threshold to flag CRITICAL (default ${DEFAULT_CRITICAL_NET_USD}).`,
+    `  --json                Emit structured JSON instead of the text summary.`,
+    '',
+    'Without --org or --user, the command auto-detects the authenticated login from',
+    '`gh api user` and probes the user usage endpoint first, then the org endpoint.',
+    '',
+    'Exit codes: 0 ok, 1 error fetching, 2 CRITICAL severity (so CI scripts can fail closed).',
+  ].join('\n');
+}
+
+function runBudgetCommand(rawArgs) {
+  let options;
+  try {
+    options = parseBudgetArgs(rawArgs);
+  } catch (err) {
+    console.error(`[${TOOL_NAME}] ${err.message}`);
+    console.error(renderBudgetHelp());
+    process.exitCode = 1;
+    return;
+  }
+
+  if (options.help) {
+    console.log(renderBudgetHelp());
+    return;
+  }
+
+  let response;
+  try {
+    response = fetchUsage({ org: options.org, user: options.user });
+  } catch (err) {
+    console.error(`[${TOOL_NAME}] ${err.message}`);
+    process.exitCode = 1;
+    return;
+  }
+
+  const report = shapeBudgetReport({
+    scope: response.scope,
+    name: response.name,
+    usage: response.usage,
+    monthKey: options.month,
+    warnUsd: options.warnUsd,
+    criticalUsd: options.criticalUsd,
+  });
+
+  if (options.json) {
+    process.stdout.write(`${JSON.stringify(report, null, 2)}\n`);
+    process.exitCode = report.severity === 'critical' ? 2 : 0;
+    return;
+  }
+
+  console.log(formatBudgetReportText(report));
+  process.exitCode = report.severity === 'critical' ? 2 : 0;
+}
+
+module.exports = {
+  runBudgetCommand,
+  parseBudgetArgs,
+  shapeBudgetReport,
+  formatBudgetReportText,
+  renderBudgetHelp,
+  currentMonthKey,
+  DEFAULT_WARN_NET_USD,
+  DEFAULT_CRITICAL_NET_USD,
+};
diff --git a/src/cli/main.js b/src/cli/main.js
index 1046af2..8e5f6d7 100755
--- a/src/cli/main.js
+++ b/src/cli/main.js
@@ -11,6 +11,7 @@ const agentStatus = require('../agents/status');
 const agentCleanupSessions = require('../agents/cleanup-sessions');
 const { finishAgentSession } = require('../agents/finish');
 const sessionSeverityReport = require('../report/session-severity');
+const budgetModule = require('../budget');
 const cockpitModule = require('../cockpit');
 const agentsStart = require('../agents/start');
 const prReviewModule = require('../pr-review');
@@ -3971,6 +3972,7 @@ async function main() {
   if (command === 'submodule') return submodule(rest);
   if (command === 'cleanup') return cleanup(rest);
   if (command === 'release') return release(rest);
+  if (command === 'budget') return budgetModule.runBudgetCommand(rest);
 
   const suggestion = maybeSuggestCommand(command);
   if (suggestion) {
diff --git a/src/context.js b/src/context.js
index 6a83402..004bab2 100644
--- a/src/context.js
+++ b/src/context.js
@@ -414,6 +414,7 @@ const SUGGESTIBLE_COMMANDS = [
   'copy-commands',
   'print-agents-snippet',
   'release',
+  'budget',
 ];
 // CLI_COMMAND_GROUPS is the grouped source of truth the `gx --help` /
 // `gx` no-args renderer uses. Each group is ordered roughly by how often a
diff --git a/test/budget.test.js b/test/budget.test.js
new file mode 100644
index 0000000..3510e86
--- /dev/null
+++ b/test/budget.test.js
@@ -0,0 +1,179 @@
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const {
+  parseBudgetArgs,
+  shapeBudgetReport,
+  formatBudgetReportText,
+  renderBudgetHelp,
+  currentMonthKey,
+  DEFAULT_WARN_NET_USD,
+  DEFAULT_CRITICAL_NET_USD,
+} = require('../src/budget');
+
+const sampleUsage = {
+  usageItems: [
+    {
+      date: '2026-05-01T00:00:00Z',
+      product: 'actions',
+      sku: 'Actions Linux',
+      quantity: 155184,
+      unitType: 'Minutes',
+      pricePerUnit: 0.006,
+      grossAmount: 931.104,
+      discountAmount: 931.104,
+      netAmount: 0,
+      repositoryName: 'gitguardex',
+    },
+    {
+      date: '2026-05-01T00:00:00Z',
+      product: 'actions',
+      sku: 'Actions macOS 3-core',
+      quantity: 150,
+      unitType: 'Minutes',
+      pricePerUnit: 0.062,
+      grossAmount: 9.3,
+      discountAmount: 0,
+      netAmount: 9.3,
+      repositoryName: 'openthread-dashboard',
+    },
+    {
+      date: '2026-05-01T00:00:00Z',
+      product: 'actions',
+      sku: 'Actions storage',
+      quantity: 134.78,
+      unitType: 'GigabyteHours',
+      pricePerUnit: 0.00033602,
+      grossAmount: 0.045,
+      discountAmount: 0.045,
+      netAmount: 0,
+      repositoryName: 'oh-my-codex',
+    },
+    {
+      date: '2026-04-01T00:00:00Z',
+      product: 'actions',
+      sku: 'Actions Linux',
+      quantity: 179300,
+      unitType: 'Minutes',
+      pricePerUnit: 0.006,
+      grossAmount: 1075.8,
+      discountAmount: 1075.8,
+      netAmount: 0,
+      repositoryName: 'codex-plugins',
+    },
+  ],
+};
+
+test('parseBudgetArgs accepts the documented flags', () => {
+  assert.deepEqual(parseBudgetArgs([]), {
+    org: null,
+    user: null,
+    json: false,
+    help: false,
+    month: null,
+    warnUsd: DEFAULT_WARN_NET_USD,
+    criticalUsd: DEFAULT_CRITICAL_NET_USD,
+  });
+  const parsed = parseBudgetArgs([
+    '--org=recodeee',
+    '--month',
+    '2026-05',
+    '--warn-usd=5',
+    '--critical-usd',
+    '50',
+    '--json',
+  ]);
+  assert.equal(parsed.org, 'recodeee');
+  assert.equal(parsed.month, '2026-05');
+  assert.equal(parsed.warnUsd, 5);
+  assert.equal(parsed.criticalUsd, 50);
+  assert.equal(parsed.json, true);
+});
+
+test('parseBudgetArgs rejects unknown flags + bad numbers', () => {
+  assert.throws(() => parseBudgetArgs(['--bogus']), /Unknown budget argument: --bogus/);
+  assert.throws(() => parseBudgetArgs(['--warn-usd=abc']), /--warn-usd must be a non-negative/);
+});
+
+test('currentMonthKey returns YYYY-MM in UTC', () => {
+  const fixed = new Date('2026-05-14T01:00:00Z');
+  assert.equal(currentMonthKey(fixed), '2026-05');
+});
+
+test('shapeBudgetReport filters by current month + product + minutes only', () => {
+  const report = shapeBudgetReport({
+    scope: 'org',
+    name: 'recodeee',
+    usage: sampleUsage,
+    monthKey: '2026-05',
+    warnUsd: DEFAULT_WARN_NET_USD,
+    criticalUsd: DEFAULT_CRITICAL_NET_USD,
+  });
+  // Should include only the 2 May Actions/Minutes items (Linux + macOS).
+  // April Linux row + May storage row are excluded.
+  assert.equal(report.actions_minutes_used, 155334);
+  assert.equal(report.net_usd, 9.3);
+  assert.equal(report.severity, 'warn'); // net 9.3 < critical 10 but > warn 1
+  const linuxRow = report.sku_breakdown.find((row) => row.sku === 'Actions Linux');
+  const macRow = report.sku_breakdown.find((row) => row.sku === 'Actions macOS 3-core');
+  assert.equal(linuxRow?.minutes_used, 155184);
+  assert.equal(macRow?.minutes_used, 150);
+});
+
+test('shapeBudgetReport surfaces critical when net spend reaches the threshold', () => {
+  const big = shapeBudgetReport({
+    scope: 'org',
+    name: 'recodeee',
+    usage: {
+      usageItems: [
+        {
+          date: '2026-05-01T00:00:00Z',
+          product: 'actions',
+          sku: 'Actions Linux',
+          quantity: 5000,
+          unitType: 'Minutes',
+          grossAmount: 30,
+          discountAmount: 0,
+          netAmount: 30,
+          repositoryName: 'gitguardex',
+        },
+      ],
+    },
+    monthKey: '2026-05',
+    warnUsd: DEFAULT_WARN_NET_USD,
+    criticalUsd: DEFAULT_CRITICAL_NET_USD,
+  });
+  assert.equal(big.severity, 'critical');
+});
+
+test('formatBudgetReportText surfaces CRITICAL verdict', () => {
+  const text = formatBudgetReportText({
+    scope: 'org',
+    name: 'recodeee',
+    month: '2026-05',
+    actions_minutes_used: 155334,
+    gross_usd: 940.4,
+    discount_usd: 931.1,
+    net_usd: 100,
+    severity: 'critical',
+    warn_threshold_usd: 1,
+    critical_threshold_usd: 10,
+    top_repos: [{ repository: 'gitguardex', minutes_used: 155184 }],
+    sku_breakdown: [{ sku: 'Actions Linux', minutes_used: 155184 }],
+  });
+  assert.match(text, /CRITICAL/);
+  assert.match(text, /Actions Linux: 155184 min/);
+  assert.match(text, /gitguardex: 155184 min/);
+});
+
+test('renderBudgetHelp covers documented flags', () => {
+  const help = renderBudgetHelp();
+  assert.match(help, /--org/);
+  assert.match(help, /--user/);
+  assert.match(help, /--month/);
+  assert.match(help, /--warn-usd/);
+  assert.match(help, /--critical-usd/);
+  assert.match(help, /--json/);
+});