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noema/docs/snapshots-replay.md
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Andy Dixon 522de3b026 feat(replay): record runtime identity; label compatibility; analyse first divergence
Snapshots, replays and experiments now record the runtime they ran under:
build (module version, VCS commit, modified tree, commit time, Go version,
platform), schema version, a digest of the non-secret configuration that
ignores secret and credential changes, personality version, policy digest,
model routing including per-mind overrides, prompt versions, deterministic
subsystem versions and timezone. A replay compares its identity with the
snapshot's and is an exact-candidate, a different-build (differences
listed) or incompatible (schema differs; the replay stops before running).
The first non-exact step is analysed into events only in the recording,
events only in the replay, and the components they belong to, labelled as
inferred; live model calls are named as their own source of difference.
Migration 0022 is additive; unrecorded identities are reported as such.
2026-08-20 21:11:27 +01:00

6.2 KiB

Snapshots, forks, export/import, replay and experiments

Snapshots and forks (spec §42)

A snapshot is a JSON archive of a mind's state at a point in its history: identity, personality, configuration, workspace and working memory, drives and affect, goals, beliefs (with evidence, versions, alternatives, links), memories (with relationships), predictions, entities, corrections, policy rules (kept by forks, never imported from archives) and conversations. It records the event sequence number at capture and a SHA-256 checksum. Cognitive events are not copied.

A fork restores a snapshot into a new mind. Every row id is remapped, so the fork never shares mutable rows with its source; references to events keep pointing at the source's immutable history, which is how the past before the fork is shared by reference (forked_from_mind, forked_from_snapshot, snapshot event_seq). After the fork the two minds diverge freely.

Compare (/minds/{a}/compare?with={b}, noemactl compare) is deterministic: counts, mean confidence, belief-by-belief differences keyed on the normalised proposition, personality and configuration field diffs, and the event-type mix.

Export / import (spec §43)

Export produces the same archive (kind: noema.mind-archive, version: 1, checksum). Nothing secret is included: provider keys, integration secret references, API tokens and sessions are not mind state and are never in an archive. Import treats the archive as hostile: size cap (32 MiB), unknown top-level fields rejected, allow-listed tables only, row caps, column-name validation, checksum must match, every id remapped, mind_id forced. Text inside an archive is data; a prompt-injection string in a memory is imported as a memory, never executed.

Replay (spec §41)

Replay rebuilds a mind from a snapshot into a disabled sandbox mind, then re-injects the source's recorded stimuli (perception and operator events after the snapshot) one at a time, stepping the real cycle code synchronously until the mind settles. Each step compares the events the source produced after that stimulus with the events the sandbox produced, ignoring bookkeeping types and normalising ids and numbers:

Label Meaning
exact same events, and every model call was served from a recording
approximate a live model call was needed; the recorded response did not match the request hash
diverged no live model call, yet the deterministic code produced different events

Divergence is reported, not hidden. Its usual causes are honest ones: the working memory changed between snapshot and stimulus, retrieval scores depend on wall-clock recency, or the code changed since the recording.

Runtime identity and compatibility

Every snapshot, replay and experiment records the runtime identity it ran under: build (module version, VCS commit, whether the tree was modified, commit time, Go version, OS and architecture), schema version (highest applied migration), a digest of the non-secret configuration (secrets and credentials never enter it; it changes only when behaviour-affecting settings change), the mind's personality version, a digest of the policies in force, the LLM role routing (including per-mind overrides), the current version of every prompt, the versions of the deterministic subsystems whose output is compared, and the timezone.

A replay compares its identity with the snapshot's and labels itself:

Compatibility Meaning
exact-candidate same build, schema, configuration, routing, prompts, policy and subsystem versions: differences can only come from state, timing or a model
different-build the schema matches but something else differs; the differences are listed. Exact steps are still exact; a diverged step may be a code change
incompatible the schema differs. The sandbox could not be a faithful reconstruction, so the replay stops before running rather than produce a misleading comparison

Snapshots taken before identities were recorded are labelled as such.

Divergence analysis

The first non-exact step is analysed: which event digests appear only in the recording, which only in the replay, and which components those events belong to (retrieval, attention, encoding, beliefs, association, predictions, goals, response, narrative, motivation, metacognition, capabilities). Components are inferred from event types and labelled as inferred: they point at where to look, not at a proven cause. Live model calls are named as a component of their own, because provider nondeterminism is a real and measurable source of difference, not one to be hidden.

The replaying router serves recorded responses by request hash (llm_calls.request_hash) and records the replayed call with replayed=true. Replays run under a forbidden capability context; no action can execute.

Experiments (spec §57)

An experiment is a snapshot, optional configuration and personality overrides, a stimulus script, expectations, a seed and a duration cap. Running it forks the snapshot into a disabled subject mind, applies overrides, feeds the stimuli and records: events by type, produced-event digests per stimulus, subject beliefs, memory and goal counts, expectation outcomes, model-call counts (live/replayed), the LLM role routing in force, duration and cycles. Results are stored and exportable (/api/v1/experiments/{id}/export includes an archive of the subject). The subject stays for comparison with the baseline.

Different models are compared by changing role routing between runs; the routing in force is recorded in each result. The seed is recorded with every stimulus for provenance; deterministic code needs no seed, and model providers do not honour one reliably.

Operating

  • UI: mind → Snapshots (take, fork, download, compare, import on the minds page), mind → Replay, top-level Experiments.
  • API: /api/v1/minds/{mind}/snapshots, /api/v1/snapshots/{id}[/archive|/fork], /api/v1/minds/{mind}/export, /api/v1/minds/import-archive, /api/v1/minds/{mind}/compare/{other}, /api/v1/minds/{mind}/replays, /api/v1/replays/{id}, /api/v1/experiments[...].
  • CLI: noemactl snapshots, noemactl compare, noemactl replay, noemactl experiments.