custodian-kernel 0.1.2

Kernel-enforced authority and spend platform for AI agents

Custodian

Custodian is a kernel-enforced authority and spend platform for AI agents. An agent cannot exceed its band or approve its own escalation because the boundary is enforced outside the agent's own process and outside its own code path — not by the agent's good behavior.

The agent submits a spend request. The policy engine decides: autonomous (within your configured band, no human needed) or escalation (over the cap, human approval required via Twilio Verify). The agent never holds the keys to both sides of that decision, so self-approval is structurally impossible, not just discouraged.

New here? Read docs/WHAT_THIS_IS.md first — a plain-language walkthrough of what this actually does, why it needs AI in exactly one place and nowhere else, and a worked real example end to end.

Wondering what this is actually for beyond one demo? See docs/BUSINESSES_THIS_UNLOCKS.md — the same enforcement pattern applied to five concrete, named business shapes, not just the one shown here.

Installation

pip install custodian-kernel

For development (clone first):

pip install -e ".[dev]"

Quickstart

# Scaffold a workspace
custodian init --dir myagent

# Edit the generated policy.yaml to configure authority bands
# (see docs/POLICY_LANGUAGE.md)

# Autonomous request (under the $2.00 default cap)
custodian request --amount 1.00 --description "API credits"

# Escalation request (over the cap — will warn about missing Twilio config)
custodian request --amount 50.00 --description "Server upgrade"

# Check authority state
custodian status

# View audit log
custodian audit

Documentation

• Architecture — design, flow diagram, privilege separation model
• Policy Language — complete YAML format reference
• Security — threat model, self-approval fix, verification model
• Verification — how to check every claim yourself
• Getting Started — 10-minute walkthrough

Tool Layer — 100 governed tools

Custodian ships a governed tool library. Every tool is a Hermes-compatible skill (SKILL.md frontmatter) that declares a custodian-band from L0–L4. The ToolRegistry auto-discovers them — no registration code needed.

custodian tools list              # show all 100 tools grouped by band
custodian tools run http-get --url https://example.com
custodian tools summary           # JSON band breakdown

Tool categories:

Category	Count	Band	Example
Utilities	8	L0	base64, hash-sha256, url-parse, json-transform, timezone, currency-convert
Web	5	L0–L1	http-get, http-post, web-scrape, web-search, news-search
Files	3	L0–L1	file-read, file-list, shell-exec (read-only allowlist)
Memory	5	L0	kv-get/set/delete/list, sqlite-query
Scheduling	5	L1	task-queue-add/list, cron-create/list/delete
Communication	6	L1–L2	email-send, sms-send, slack-message, discord-webhook, webhook-post, push-notification
Docker	4	L1–L2	docker-list, docker-logs, docker-start, docker-stop
GitHub	3	L0–L1	github-file-read, github-issue-create, github-pr-list
NVIDIA NIM	4	L2	nim-model-list, nim-job-submit, nim-job-status, nim-cost-estimate
Stripe (extended)	8	L2–L3	stripe-balance, stripe-customer-lookup, stripe-invoice, stripe-refund
Financial AI	5	L2–L3	modal-run, huggingface-infer, openai-complete, anthropic-complete
Calendar	5	L1–L2	calendar-list, calendar-create, calendar-update

Tools with missing credentials return {"ok": false, "stub": true} — the framework works without any env vars configured; stub tools show in the registry with their band and description so the capability surface is visible during review.

Authority bands

Band	Policy	Use case
L0	Always autonomous, no spend	Read-only data fetching
L1	Autonomous, trivial side effects	Creating records, sending low-stakes messages
L2	Autonomous up to per-action cap	AI inference, Stripe calls under threshold
L3	Always escalates to operator	Refunds, subscription changes, payouts
L4	Always escalates, unlimited scope	Reserved for future high-stakes tools

What's real right now

• A real Stripe (test-mode) PaymentIntent is on record: pi_3TkZWEPfSF4TGXT90AWlrnle — confirm it at Stripe's own API or dashboard.
• A real Twilio Verify integration sends SMS approval codes to an operator's phone. The code is never written to any file the agent can read.
• A real, operator-only kill switch (custodian kill --by <name> / custodian resume --by <name>) is wired into the live, authoritative spend.py — not a separate demo path. Verified live: a real autonomous spend succeeded, the kill switch was engaged, the exact same request was denied by the real script running inside the live sandbox, then released, then the real spend succeeded again. The full sequence is in the real audit log.
• 1,110 passing tests, tested with Python 3.13.
• The test suite includes test_self_approval_regression.py — a regression test for the exact security bug this design prevents. The fix was proven by deliberately reintroducing the bug, confirming the test failed, then restoring the fix. That test exists so the bug can never silently return.
• Public commit history at git.argobox.com/KeyArgo/hermes-hackathon-2026.

Don't take any of this on faith — run python3 verify_kit.py yourself. One command re-runs the test suite, actually reintroduces the security bug live to prove the regression test catches it (then restores the original file), and pulls fresh data straight from the real public dashboard. See docs/VERIFICATION.md for the full manual breakdown too.

Limitations

• Only one approval backend is shipped: twilio_verify. Backends named other than twilio_verify or none are rejected at policy validation time.
• Only one storage backend is shipped: SQLite (via SqliteStorage).
• No multi-tenant support. No plugin marketplace. No general-purpose expression language in the policy DSL — the match vocabulary is a fixed, small set (skill name, context flags, spend-amount threshold).
• No third-party security audit has been performed.