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Aura/docs/design/contracts/c29-self-description.md
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claude bd7585b609 audit(cycle 316): drift disposition, bench seed docs + ratified re-pin, C29 scope paragraph
Cycle-close audit for the self-description cycle. Architect: drift_found
(mild), core holds -- the gate is pure string shape in core imported by
every seam (C28), the engine never evaluates description text (C17/inv
10), determinism pins untouched (C1); the store boundary is gated by
construction with the raw write private; Op::Doc is a closed typed
construct (C25). Regression: aura-bench green (exit 0) after one
cycle-caused infra fix and one ratified re-pin.

Infra fix: the bench campaign seeds (BP_SMA_A/B) predate C29 and were
refused by the store gate (exit 2, infrastructure-first rule) -- both
thread the authored sma_signal meaning line.

Ratify: cli_fixed_cost's run_line_fnv moved because bench_sma_a.json now
carries its doc -- the blueprint's content id shifts exactly as the spec
anticipates for fixtures gaining docs; campaign result fingerprints are
unchanged (descriptions stay out of execution, C29). Baselines re-pinned
via aura-bench pin (throughput baselines re-pinned in the same sweep,
all deltas within tolerance at pin time).

Drift disposition:
- [high] C29 guarantee overclaim vs emit/binding-column vocabularies ->
  contract now carries an explicit Scope paragraph naming the residue,
  tracked as #321 (also covers the [medium] non-roster schema walk gap).
- [low] Delay's meaning line cited the stale C5 for the delay register;
  corrected to C9.

refs #316, refs #321
2026-07-23 20:42:02 +02:00

4.3 KiB

C29 — Self-description: every surface explains itself

Guarantee. Every closed-vocabulary entry the binary exposes carries a one-line meaning, enforced at the seam where the entry enters the system; everything entering the content-addressed store describes itself; a refusal for a missing description names the entry, the field, and the rule. One shared deterministic gate — doc_gate in aura-core, importable by every seam per C28; it fails on an empty/whitespace doc and on a doc that normalizes to the entry's own name (DocGateFault::{Empty, RestatesName}) — guards three seams:

  1. Compile/unit seam (engine-shipped). NodeSchema.doc is a required field, so the compiler enumerates every construction site; metrics and tap slots are schema carriers (MetricSchema / TapSchema, id + doc); blocks (BlockSchema.doc, the pre-existing model) and tap folds (the registry roster, C27) already carried theirs. The coverage walk (aura-cli/tests/self_description.rs) asserts the gate over all five vocabularies — the engine satisfies its own law.
  2. Load seam (extension). load_crate walks every charter-checked type id and gates the resolved schema's doc; a fault refuses the load naming type and rule (ProjectError::UndescribedVocabularyEntry). Field presence is compile-enforced for any crate built against the new core; the load gate catches the shape violations the compiler cannot see across the cdylib boundary — the empty-string alibi and the name restatement.
  3. Register seam (data plane). The registry's public put_blueprint parses the canonical bytes and requires a gate-passing doc on the root composite and on every named nested composite — the gate guards the store boundary itself, so the register verb, every register-then-run sugar path, and any future caller are gated by construction. The op-script vocabulary carries the doc op as the builder .doc(...)'s twin (C25: a closed, typed metadata construct). Process/campaign documents take an additive-optional top-level description, gated only when present (DocFault::BadDescription).

Scope at this record's writing (#321). The gate walks five vocabularies — process/campaign blocks, metrics, tap slots, tap folds, and the closed node roster — plus the document description and the three seams above. Recorded residue, tracked as #321 and not silently claimed: emit_vocabulary() and binding_column_vocabulary() remain bare name arrays, and builder schemas outside the closed node roster (e.g. the internal tap recording sink) carry compile-required but shape-unwalked docs. Closing #321 widens the walk and removes this paragraph.

Id treatment. Description fields that serialize participate in the content id and are blanked for the identity id, exactly as Composite.doc (strip_debug_symbols); NodeSchema is not serialized (C24), so node docs move no id. Documents have no identity projection — their pair is: absent description is byte-identical to the field-less form (existing content ids stable), present participates.

Forbids. The engine evaluating description text — the gate is deterministic string shape, never content judgement (no freetext logic hole; C17 / domain invariant 10 untouched). A description influencing execution, identity ids, or determinism (C1). Retroactive invalidation of already-registered artifacts — the gate guards the write path only (the raw in-crate write survives as the store-mechanics and back-compat witness: pre-C29 doc-less entries stay readable). Machine-invented meaning lines — an authored text is corrected against the source, never weakened to an empty string or a name restatement.

Why. The audience is headless LLM agents and scripts (#319 ruling), for whom the binary is the only always-present teacher. Field evidence 2026-07-22 (#314): an agent holding only the release binary had to recover execution semantics and document schemas by CAS forensics — the removed failure class is exactly that forensic recovery.

Rendering of the carried texts on the help/introspection surfaces is #315; the generated agent bootstrap card is #267; a fold introspection surface is blocked on #310.