Tempus DDB

The B2A security gate for autonomous agent actions

Local-first · Signed policy · Workload identity · Fail-closed receipts · MCP-native

Status: beta (0.4.0 source line). Signed policy, identity lifecycle, Vault-backed signing, and the single-instance GitHub executor are implemented. Distributed permit consumption and independent external checkpoints are not.

Roadmap · Security · Threat model · Contributing

Tempus sits between an agent's intent and an external effect. The agent signs what it wants to do, Tempus issues a short-lived permit, an executor performs the effect, and the executor plus Tempus sign the outcome. A human is not part of the transaction loop; humans only inspect the resulting history.

Product invariant: no Tempus permit, no effect; every effect produces a verifiable receipt.

The 0.4.0 source tree implements the local permit protocol, signed policy bundles, rotation and revocation, a generic mediated executor, Vault Transit signing, and a packaged credential-isolated GitHub REST adapter. It does not yet include distributed permit consumption, external checkpoints, or a web audit console. Read THREAT_MODEL.md before relying on the current security boundary.

What is implemented

• Stable machine contracts with explicit schema_version values.
• Separate Ed25519 identities for the Tempus gate, requesting agent, and executor.
• Immutable, gate-signed agent registration receipts. Registrations cannot be silently overwritten.
• Signed, versioned deterministic policy bundles. Each permit binds its policy digest, reproducible evidence digest, closed reason codes, and executor constraints.
• Tenant-scoped delegation, signed key rotation and revocation, historical key-at-time verification, and emergency invalidation of unconsumed permits.
• A provider-neutral signer boundary shared by the gate and executor. Local Ed25519 and Vault Transit use the same exact-byte contract; provider outages fail closed.
• ALLOWED or BLOCKED authorization before execution.
• Short-lived permits, deterministic action IDs, and idempotency conflict detection.
• Single-consumption execution receipts; an identical retry is idempotent and a conflicting second outcome is rejected.
• End-to-end verification of intent, gate authorization, executor outcome, and receipt linkage.
• A generic TempusExecutor that verifies gate identity, tenant, expiry, permit integrity, and single consumption before a demo adapter produces an effect.
• Signed executor observations for STARTED, SUCCEEDED, FAILED, and UNKNOWN, with restart recovery that never retries an ambiguous external effect.
• A packaged GitHub executor for github.create_issue and github.create_pull_request; it binds the exact repository and allowlisted arguments from the signed intent and keeps GITHUB_TOKEN outside the agent payload.
• Money is optional metadata in the same universal action envelope; financial and non-financial actions use the same protocol.
• An autonomous MCP surface that hides administrative, legacy, and destructive tools by default.

B2A flow

agent signs intent
        │
        ▼
Tempus request_action ── BLOCKED ──► signed denial trace
        │ ALLOWED
        ▼
single-use, expiring permit
        │
        ▼
executor performs effect and signs outcome
        │
        ▼
Tempus commit_outcome ──► final signed execution receipt
        │
        ▼
human or machine calls verify_trace

Tempus becomes an unavoidable toll when the executor exclusively holds the downstream credential. The packaged GitHub adapter implements that boundary for its supported actions in a single-instance deployment. Operators must ensure the requesting agent cannot read the executor's environment or key material.

Install

Python 3.10 or newer is required.

Install the published beta from PyPI:

python -m pip install tempus-ddb

For development, clone https://github.com/elbuilder77/tempus-ddb.git and install python -m pip install -e ".[dev]".

Bootstrap identities

tempus init creates the local gate key and database, then records the gate as the signed delegation root. This is deployment-time bootstrap, not a human approval step for each action.

tempus init
tempus keygen --output agent.keys.json
tempus keygen --output executor.keys.json

tempus register-agent --alias purchasing-agent --agent-keyfile agent.keys.json \
  --metadata '{"tenant_id":"acme"}'
tempus register-agent --alias purchasing-executor --agent-keyfile executor.keys.json \
  --metadata '{"tenant_id":"acme"}'
tempus doctor --json
tempus conformance --signer

The gate signer configuration is the global --keyfile and defaults to keys.json. Production deployments should use the non-secret Vault Transit configuration described in docs/VAULT_TRANSIT_SIGNER.md; the workload authenticates to Vault without placing a private key in the file.

Install a production policy

Bootstrap installs a signed compatibility baseline so the first local flow works; it is not a production allowlist. Before a production effect, copy config/policy.github.example.json, replace the repository scope and executor public key, then install it. A new policy version retires the previous active policy for the same tenant without deleting historical bundles.

tempus install-policy --policy acme-github-policy.json
tempus list-policies

Policy evaluation is deterministic and rejects unknown constraints, floating-point input, oversized input, tenant/resource/action mismatches, excessive TTL, disallowed executors, and money metadata outside the configured currency or minor-unit ceiling.

Python quickstart

import json
import time
from tempus_ddb import TempusDDB, gen_keys

gen_keys("gate.keys.json")
gen_keys("agent.keys.json")
gen_keys("executor.keys.json")

gate = TempusDDB("tempus.db", "gate.keys.json")

with open("gate.keys.json", encoding="utf-8") as handle:
    gate_id = json.load(handle)["public_key"]
with open("agent.keys.json", encoding="utf-8") as handle:
    agent_id = json.load(handle)["public_key"]
with open("executor.keys.json", encoding="utf-8") as handle:
    executor_id = json.load(handle)["public_key"]

gate.register_agent(gate_id, "tempus-gate", '{"can_delegate":true}')
gate.register_agent(agent_id, "purchasing-agent", "{}")
gate.register_agent(executor_id, "purchasing-executor", "{}")

intent = json.dumps({
    "schema_version": "tempus.action-intent.v1",
    "tenant_id": "acme",
    "agent_id": agent_id,
    "idempotency_key": "purchase-2026-07-16-001",
    "action_type": "purchase",
    "resource": "vendor-api/compute-credits",
    "requested_at": time.time_ns() // 1_000,
    "input": {"sku": "compute-credits"},
    "money": {"amount": "25.00", "asset": "USD", "beneficiary": "vendor-42"},
})

authorization = json.loads(gate.request_action(intent, "agent.keys.json", 60))
permit = authorization["authorization"]
assert permit["decision"] == "ALLOWED"

# The executor performs the external effect only after checking the permit.
outcome = json.dumps({
    "schema_version": "tempus.action-outcome.v1",
    "authorization_id": permit["authorization_id"],
    "action_id": permit["action_id"],
    "status": "SUCCEEDED",
    "external_reference": "vendor-tx-9182",
    "output": {"credits_added": 1000},
})

receipt = gate.commit_outcome(
    permit["authorization_id"],
    outcome,
    "executor.keys.json",
)
verification = json.loads(gate.verify_trace(permit["action_id"]))
assert verification["status"] == "VERIFIED"
assert verification["phase"] == "COMPLETED"

For remote transports, use request_action_signed(...) and commit_outcome_signed(...). The requesting agent and executor sign locally, so their private keys and keyfiles never enter the gate process.

Demos and Scenarios

The repository includes runnable end-to-end demonstrations covering security guards, B2A flow, and tamper detection: Examples create ephemeral databases and keys and remove them when they finish.

1. Commercial Demo (examples/commercial_demo.py)

Demonstrates the Phase 2 mediated-executor foundation and bypass prevention against a simulated downstream API.

python examples/commercial_demo.py

Key checks performed:

• Direct Bypass Attempt: Rejected (agent lacks downstream API secret token).
• Authorized Execution: Agent signs intent → Tempus Gate validates → Mediated Executor verifies permit → API executed.
• Replay Guard: Re-using a consumed permit is rejected by the Executor.
• Expiry Guard: Expired permits are rejected.
• Tamper Guard: Altered permit fields invalidate the signature and are rejected.
• Cross-Tenant Guard: Permits issued for a different tenant ID are blocked.
• Trace Verification: Full cryptographic audit trace verification passes end-to-end.

2. Decision Chain Scenario (examples/decision_chain.py)

Simulates an autonomous bot lifecycle (Genesis → Decision 1 → Decision 2) with chain validation and JSON export:

python examples/decision_chain.py

3. CLI Tamper Detection (examples/tamper_detection_cli.py)

Demonstrates tamper detection using the Rust CLI by simulating unauthorized modifications to recorded traces:

python examples/tamper_detection_cli.py

4. Code Examples (examples/)

Additional standalone scripts in examples/:

• examples/basic_record.py: Basic decision recording.
• examples/full_agent_flow.py: Complete multi-agent authorization flow.
• examples/verify_chain.py: Cryptographic chain verification.

python examples/full_agent_flow.py

GitHub executor

The installed tempus-github-executor command performs real GitHub REST writes for two exact action types:

• github.create_issue, with resource set to owner/repository and allowlisted title, body, and labels input fields.
• github.create_pull_request, with resource set to owner/repository and allowlisted title, head, base, body, and draft input fields.

The executor reads GITHUB_TOKEN from its own environment. Do not put that variable in the requesting agent's environment or include credentials in an intent.

$env:GITHUB_TOKEN = '<executor-only token>'
tempus-github-executor `
  --permit permit.json `
  --executor-db github-executor.db `
  --executor-keyfile executor.keys.json `
  --gate-id <gate-public-key> `
  --tenant-id acme

The executor reuses a bounded SQLite connection pool (eight connections by default). Use --executor-pool-size to tune that local concurrency limit for the deployment. SQLite still serializes writes; this removes per-operation connection setup but does not claim horizontal or multi-region durability.

The command emits a signed tempus.action-outcome.v1. Submit it to the gate through commit_outcome_signed(...) or tempus_commit_outcome_signed. Exit code 2 means the external result is UNKNOWN; the signed observation must be investigated and the operation must not be retried automatically.

Performance Benchmarks

Tempus DDB includes a benchmarking tool to evaluate transaction throughput and validation latency:

python examples/benchmark.py --records 1000

To output machine-readable JSON:

python examples/benchmark.py --records 1000 --json

Optimizations active in v0.2.1+:

• SQLite Write-Ahead Logging (WAL mode) with PRAGMA synchronous = NORMAL and busy_timeout = 5000.
• In-memory key caching to prevent disk I/O bottlenecks during hot-path transactions.
• Max LTO release compilation (opt-level = 3, lto = true, codegen-units = 1).

Stable contracts

Authorization decisions are ALLOWED or BLOCKED. Execution outcomes are SUCCEEDED or FAILED. Executor observations are STARTED, SUCCEEDED, FAILED, or UNKNOWN. Trace verification is VERIFIED or INVALID.

Phase 3 fields are additive to the v1 authorization contracts. Executors require and verify them, while historical Phase 2 receipts keep their original signature semantics. See COMPATIBILITY.md for support/deprecation rules and MIGRATION_0.4.md for the 0.3.x upgrade procedure.

MCP autonomous mode

The default MCP surface exposes only machine-to-machine execution and read-only audit operations. The agent and executor must sign their own payloads; the gate never receives their keyfile paths:

Configuration:

{
  "mcpServers": {
    "tempus": {
      "command": "tempus",
      "args": ["mcp", "start"],
      "env": {
        "TEMPUS_MODE": "autonomous",
        "TEMPUS_GATE_KEYFILE": "keys.json"
      }
    }
  }
}

Provisioning should run separately from the agent-facing MCP process. The following flags are deliberately off by default:

Human audit

Humans are readers, not approvers:

tempus trace --action-id <action-id>
tempus verify-trace --action-id <action-id>
tempus list-agents
tempus list-policies
tempus identity-events

The future audit console will be read-only and derive its views from these contracts.

Legacy ledger

The original record, validate, list, count, and export interfaces remain for compatibility and migration. They are a voluntary flight recorder and do not enforce the B2A toll. New autonomous integrations should use the signed action authorization flow; local keyfile MCP tools are development compatibility only.

Security boundary

This implementation detects receipt, policy, evidence, and trace alteration; rejects unregistered or revoked actors; prevents conflicting idempotent requests; and prevents two outcomes from consuming one permit. It does not yet prevent deletion or rollback of the entire local database, nor bypass by an agent that still possesses downstream credentials. Read THREAT_MODEL.md before using Tempus for high-impact production actions.

Roadmap

The next release line focuses on large-ledger streaming, durable receipt events, independent rollback detection, and operating procedures. See ROADMAP.md for milestones and explicit exit criteria.

Development

See CONTRIBUTING.md for setup, security reporting, and pull-request requirements. The complete local verification set is:

cargo fmt --check
cargo clippy --all-targets -- -D warnings
cargo test --all-targets
ruff check .
pytest -p no:cacheprovider
python -m maturin build

License

MIT. See LICENSE.