Module experience 

Experience-memory tier (DocTrace, arXiv:2606.10921).

DocTrace’s two-tier idea: tier 1 is the raw memory store (everything mnemo already does); tier 2 is an experience memory that caches a successful retrieval/reasoning plan — the query signature, the steps taken, the chunks that led to a confirmed-good outcome, and an outcome score — and replays that plan when a structurally-similar query recurs, instead of re-running full retrieval from scratch.

This is implemented as a mode, not a new store: plans are persisted as ordinary [MemoryRecord]s carrying the reserved EXPERIENCE_PLAN_TAG with the plan payload in metadata. That buys backend-agnosticism (DuckDB + PostgreSQL, unchanged schema) and RBAC/consent (scope + ACL) for free, and lets the existing remember write-path handle hashing, embedding, and audit events.

Two new ops (gated)

• REMEMBER_PLAN (execute_remember_plan): persist a plan, but only when its outcome_score clears DEFAULT_SUCCESS_THRESHOLD — failures are never cached.
• RECALL_PLAN (execute_recall_plan): on a new query, return the best stored plan whose query signature matches above a similarity threshold, or a miss.

Both are gated behind MnemoEngine::with_experience_memory; with the mode off (the default) REMEMBER_PLAN is a validation error and RECALL_PLAN always misses, so default behaviour is unchanged. Plan records are also excluded from ordinary recall (they are replayed only via RECALL_PLAN).

Signature & similarity

A query signature is its normalized significant-token set (signature_tokens); structural similarity is the jaccard overlap of two signatures. This is deterministic and backend-/embedder-agnostic (works under NoopEmbedding), which is what the v0 replay gate needs; a learned signature is a later knob.

Structs

CachedPlan

A replayable plan plus the similarity that matched it.

PlanPayload

The cached plan payload, serialized into the record metadata.

RecallPlanRequest

RECALL_PLAN input.

RecallPlanResponse

RECALL_PLAN output.

RememberPlanRequest

REMEMBER_PLAN input.

RememberPlanResponse

REMEMBER_PLAN output.

Constants

DEFAULT_SIMILARITY_THRESHOLD

Default Jaccard threshold above which a stored plan is replayed.

DEFAULT_SUCCESS_THRESHOLD

Plans scoring below this outcome are treated as failures and never cached.

EXPERIENCE_PLAN_TAG

Reserved tag stamped on every experience-tier plan record. Plans are excluded from ordinary recall and read back only via RECALL_PLAN.

PLAN_METADATA_KEY

Metadata key under which the PlanPayload is serialized.

Functions

execute_recall_plan

RECALL_PLAN — return the best replayable plan for a query, or a miss.

execute_remember_plan

REMEMBER_PLAN — persist a successful plan into the experience tier.

jaccard

Jaccard overlap |A∩B| / |A∪B| of two signature token sets. Returns 0.0 when both are empty.

signature_tokens

Normalize a query into its signature token set: lowercase, split on non-alphanumerics, drop tokens shorter than 3 chars, dedup, and sort so the signature is order-independent.