Safety and testing

Test the boundary before you trust the workflow.

Check that allowed work gets through, protected actions wait for a person and blocked requests stay blocked. Then inspect the record and know exactly what it can and cannot establish.

hash
sha-256 over canonical json
format
jsonl · documented · versioned
checkpoint
separate custody required
verifier
open source · apache-2.0
sample head
d02b6f19
01 · Integrity

Break the chain and watch verification fail.

Each entry carries a hash that covers its own content and the hash of the entry before. Alter one line without rewriting everything after it and the verifier reports the first mismatch. A complete rewrite can be detected against a trusted checkpoint retained outside the ledger.

Tamper-evident means changes are detectable against a retained chain and a trusted checkpoint. It does not make the host or its storage tamper-proof.
Break the chain · 6 entries · docs-ops v1.0 · sample data
seqactionverdictprevhash
01 crm.read allow genesis 3f61a0c9
02 docs.search allow 3f61a0c9 a84d2e17
03 docs.list allow a84d2e17 c2917b5e
04 docs.publish · 75 documents hold c2917b5e 6e0f93ad
05 approve 04 · a.khan allow 6e0f93ad f57c4b20
06 mail.send · external deny f57c4b20 1b9e6d4c
simulated integrity check · shortened hashes chain intact · 6 entries · 0 gaps · sample checkpoint matches
  1. 01
    HashSHA-256 over the canonical JSON of the entry, including the previous hash.
  2. 02
    AnchorA checkpoint records the chain head. The prototype uses a local witness; independent custody and any publication schedule must be configured and verified per pilot.
  3. 03
    VerifierAn open-source tool that checks an exported record against the chain and the anchor. Runs outside Cairn.

Illustration only: the hashes and results are simulated. No cryptographic verification runs on this page. The current prototype checks its packaged record against a supplied key and local witness; that does not establish independent historic custody. Read the export and verification limits.

02 · Replay

Trace any decision back to the rule.

A held publication should still make sense months later. Every entry names the request, the policy version and the rule that fired. Re-running the decision needs the original inputs, prior state and exact policy to have been retained; the technical pack lists what that retention involves.

Move the marker to inspect a sample entry. This illustration does not re-run the policy or verify a real record; its hashes are shortened.

Replay · ledger.jsonl · seq 18196 to 18204sample data
sample replay · docs-ops v1.0 · verdict hold · matches sample
seq
18204
ts
2026-09-05T07:41:12Z
agent
ops-agent-07
action
docs.publish · 75 documents · Team handbook
policy
docs-ops v1.0
rule
docs-bulk-review
verdict
hold
hash
d02b6f19
03 · Boundary

Know where the controls apply, and where they stop.

Protection depends on the tools connected, the permissions granted and the rules configured. The left column is what Cairn addresses; the right is what still needs other controls. Both are stated so an assessor does not have to infer them.

What the controls address
  1. 01A compromised agent. Hostile instructions change what an agent tries to do. Requests routed through Cairn are still checked, provided the agent cannot bypass that route.
  2. 02Tool misuse. A connected action is held or denied when it breaks a rule, even if the agent holds credentials for the tool.
  3. 03Changes to retained records. Hash verification detects inconsistent entries; a trusted, separately retained checkpoint can reveal a full rewrite.
  4. 04Unexplained decisions. The recorded policy identity and rule show why an action was allowed, held or denied.
What needs other controls
  1. 01A compromised host running Cairn. Hash chaining cannot protect the running process. Access control, separately held checkpoints and tested recovery are deployment requirements.
  2. 02A tool that lies. Cairn records what was asked and what was answered. Validating the answer is the workflow's job where it matters.
  3. 03Gaps in your rules. Cairn enforces what you configure. Range finds gaps under tested conditions; it cannot show every risk is covered.
04 · Pilot

Agree what the pilot must prove.

For each workflow, agree the tests up front and record where controls work, where they fail and what sits outside the boundary. Your organisation decides whether the results meet its needs; Cairn does not interpret regulation or certify compliance.

controlwhat to testwhat to inspect
Action boundariesTry an unapproved tool, an out-of-scope target and a direct route around the gateway.Denied requests and network checks, alongside permitted tasks that succeeded.
Human approvalsRequest a protected change, try self-approval, then change the arguments after review.The exact request, policy, reviewer and decision; a separate check that execution is bound to the approval.
Record integrityAlter or remove an event and compare the export with an independently retained checkpoint.Verification output and the custody of the trusted checkpoint.
Failure and recoveryInterrupt a dependency or restart a component during a controlled trial.Whether actions stop safely, approvals stay valid and recovery preserves the record.
05 · Open core

Inspect your records outside Cairn.

The ledger format and verifier are open. Exported records can be checked without the product, against the retained chain and the separately held checkpoint. The policy engine, approval queue, test harness and prototype console are Apache-licensed. Planned commercial services cover administration, managed operation, integration and support; availability and scope must be agreed for each pilot.

verification result · simulated example
sample record · 18,204 entries · shortened hashes
illustrative result: chain intact · 0 gaps
sample checkpoint matches · head d02b6f19
01Ledger formatJSON Lines, documented, versioned.
02VerifierOpen tool for retained exports.
03AnchorsSeparately protected checkpoints, configured per deployment.
For technical review

Give your technical team the details.

The record format, verifier source and notes on control boundaries, testing and known limitations.