Elamur Groupantsretention-digest-reuse
The groupant beside world/src/knowledge/retention.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | source derived partial | forward |
| ast | partial | ../../syntax.json |
| cost | prospective source cost | cost |
| descriptant | present | epoch-memory |
| invariant | source derived partial | invariant |
| tests | bounded named actual code | checks |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
retention-digest-reuse-complement | behavior_complement | source derived inner bound | behavior-complement |
retention-digest-reuse-preimage | reverse_reconstruction | partial relational specification | reverse-reconstruction |
retention-digest-reuse-number-substitution | identity_projection | source derived partial | number-substitution |
retention-digest-reuse-least-witness | ordered_selection | source derived partial | least-witness |
retention-digest-reuse-assessment-separation | noninterference | source derived partial | assessment-separation |
retention-digest-reuse-query-only | state_effect_relation | source derived partial | query-only |
Model text
Subject: world/src/knowledge/retention.rs at manifest source SHA. Horizon: one terminating call or explicitly named load prefix on finite synthetic inputs, pinned dependencies and ordinary allocation/I/O. This is a source-derived partial model; finite tests do not establish universal correspondence.
forward
Reject foreign course before scanning. Iterate retained ledger in ascending key order; serialize/hash (course,key,explain,facts,exercises) for each key and return the first equality. Exhaustion returns None. This is a read-only lookup, not learning or reservation.
invariant
Some(n) names an existing matching ledger key with no earlier match. Placeholder lesson number and assessment fields are not digest inputs; exercise labels and option order are included.
cost
For m examined entries and teaching serialization bytes B, O(m*B) serialization/hash and O(B) temporary bytes; early exit cuts m. No memoization or optimization claimed.
behavior-complement
Type: behavior_complement. In state/lesson/result transitions, exclude successful cross-course lookup, Some(n) for a nonmatching or absent key, and a later key when an earlier match exists. Assessment-only edits cannot change matching membership with teaching fields fixed.
reverse-reconstruction
Type: reverse_reconstruction. Some(n) requires matching course, digest equality at n, and inequality at every smaller key; later ledger rows are arbitrary. All placeholder n/title/file/test/exam values remain possible. None means no key matches. Hash equality does not uniquely recover teaching strings without additional assumptions.
number-substitution
Type: identity_projection. Each stored key replaces the candidate placeholder number in the digest; otherwise identical teaching can be discovered at several retained IDs. Domain and fixed-source assumptions are those above; this is a source-derived constraint, checked only by the bounded named oracle where applicable.
least-witness
Type: ordered_selection. BTreeMap key order, not insertion order, resolves multiple matches. Deleting the least matching key reveals the next compatible antecedent. Domain and fixed-source assumptions are those above; this is a source-derived constraint, checked only by the bounded named oracle where applicable.
assessment-separation
Type: noninterference. Tests/exams, file/title/level/stars and placeholder number do not enter T_key. Exercises do, including gold labels; this is teaching/assessment separation rather than blanket label independence. Domain and fixed-source assumptions are those above; this is a source-derived constraint, checked only by the bounded named oracle where applicable.
query-only
Type: state_effect_relation. No student fields or ledger entries mutate during reuse. A returned number is evidence of hash membership, not a fresh-process retention-quality score. Domain and fixed-source assumptions are those above; this is a source-derived constraint, checked only by the bounded named oracle where applicable.
parent-interaction
Material parent composes read-only reuse and separate frontier queries; callers choose reuse versus allocation. Course guard precedes per-key hashing, first match prevents later serialization; no train/read is called.
checks
knowledge::retention::tests::oracle_reuse_fiber_selects_smallest_of_multiple_antecedents directly executes this helper or its containing load/reuse path with literal expected results. Full source and selected test body reviewed; no implementation-copy oracle. Exact names, profile repetitions and mutation receipts are recorded in the wave34 evidence summary. These are finite synthetic witnesses; unobserved cases and opaque dependencies remain gaps.
epoch-memory
2026-10-31 wave34: prospective relations saved before test additions. Production bytes preserved. This new finer scope retains its parent's earlier models and history. Shared partial syntax is generated twice and compared; no semantic AST or solver claimed. No teacher, corpus, model loading, successful examination, training or lesson replay is credited as persistent knowledge.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/world/src/knowledge/retention.rs.groupant/material.groupant/digest-reuse.groupant/