Assay is append-only in the app. There is no general edit of a span or a turn. That does not stop someone who can open the store file from changing a row and saving it. From 0.49.0 the store also carries a hash-linked log. A rewrite is detectable. It is not prevented. Assay never calls an unwitnessed chain immutable. This is not a blockchain. There is no public copy of your turns.

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Three grades

Every surface that talks about integrity should name one of these:
GradeWhat is trueWhat is not true
unsealedThe log is not on yet. Old rows could have been edited before seal.Nothing about later edits.
chainedThe row is in the hash-linked log. A lazy edit of one hashed field fails assay verify.Someone who rebuilds every hash in the file still passes a local walk.
anchoredA witness outside this file has a receipt for a head that covers this row.Root on the machine can still delete the disk. They cannot make an old receipt match a new history.
The product claim — “somebody cannot quietly rewrite a session and present the file as original” — is the anchored grade. chained is what you get on the way there. It still catches accidents.

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What is hashed

Each new span or turn is hashed onto the previous head. The hash covers the fact as stored: who, when, which sitting, tokens, cost, and a hash of the message text. Not hashed:
  • The sealed ciphertext of the conversation (you may rotate keys; the hash of the plaintext still binds the words)
  • Labels you add later (type, objective, product, cost correction)
A label added after capture does not break the chain. That is on purpose. Rows that existed before you sealed the store stay legacy. Seal records a digest of what was there. It does not time-travel.

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Seal

A new empty store from 0.49.0 writes genesis on first open. A store that already had rows stays unsealed until you say so: 
assay seal --yes
That cannot be undone. New writes then chain. --yes is required. If a binary older than 0.49.0 kept writing after seal, those rows sit outside the chain and assay verify fails. Chain them without a new genesis: 
assay seal --catch-up --yes
Rows from before seal stay unchained. Upgrade the binary that writes the store before you rely on the chain. Config and binary must match. assay --version is the check. These verbs are SQLite. Pass --db. They do not walk a Postgres store.

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Verify

assay verify
assay verify --strict
assay verify --json
Walks the log, recomputes hashes, checks that chained facts still match.
ResultExit
Chain matches0
A hashed field was edited, or post-seal rows were not chained1
Unsealed, without --strict0 (warning)
Unsealed, with --strict1
Run this on a schedule. If the job ignores a non-zero exit, you will not see a break.

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Witness (assay attest)

Local verify is necessary and not enough. The operator who owns the file can rebuild the chain. assay attest builds a checkpoint of the current head (store id, sequence, head hash) and sends it to a witness you configure. 
{
  "attest": {
    "witness": "none",
    "every": "30m"
  }
}
witnessWhat happens
none (default)No network. Grade stays chained at most. Never printed as anchored.
httpsPOST { "digest" } to attest.url. Nothing else: no content, no meta, no principal, no session.
otsDigest to public OpenTimestamps calendars. A calendar receipt that has not confirmed on Bitcoin is not anchored. Until then the grade is chained.
assay attest --dry-run
assay attest
--dry-run prints the digest and sends nothing. Sweep submits when witness is not none. An old receipt binds the head at that sequence. History after that seq is chained-only until the next attest.

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What this does not do

  • Stop someone with root from destroying the disk.
  • Recover conversation text after shred. Lose the key and the words are gone.
  • Force every install onto the network. Default witness is none.
  • Make pre-seal rows retroactively anchored.
See Honesty for numbers, Privacy for keys and what may leave, CLI for the verbs, Config for attest.