0a17c49693
Phase 3.3 of the generalization arc. Estimation (ADR-0175), deduction serving (ADR-0256) and curriculum serving (ADR-0262) had each written the same seal -> ratify -> SHA-verify -> serve-gate machinery. core/ratified_ledger.py now owns it and states the four rules once: only sealed practice writes; tamper-evidence is structural (a load that cannot reproduce content_sha256 REFUSES); ceilings are not negotiable at the call site; absent evidence is never a license. Each capability keeps a thin adapter that names its artifact and preserves its public API. One real difference is now declared rather than implied: missing_ok distinguishes a ledger a capability SHIPS with (absence = broken deployment, refuse) from one whose practice volume is still being built (absence = nothing earned yet, serve disclosed) — curriculum serving is the second kind today. Safety property is byte-identity, asserted not assumed: re-sealing the committed 25-band deduction ledger through the bridge reproduces it byte-for-byte, so no artifact and no lane pin moves. Effect: a new subject arena now needs a gold corpus and a band key, not a re-implementation of ratification — which is what §3 meant by sequencing the bridge ahead of the second subject. [Verification]: tests/test_ratified_ledger_bridge.py 8 passed; core test --suite deductive 252 passed; estimation/license test set 355 passed; committed deduction ledger byte-identical after reseal.
80 lines
3.8 KiB
Markdown
80 lines
3.8 KiB
Markdown
# ADR-0263 — The ratified-ledger bridge
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- **Status:** Proposed
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- **Date:** 2026-07-24
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- **Arc:** generalization Phase 3.3 (docs/plans/generalization-arc-2026-07-24.md §2)
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- **Governs:** `core/ratified_ledger.py` and the three adapters over it —
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`generate/determine/estimation_license.py`, `chat/deduction_serve_license.py`,
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`chat/curriculum_serve_license.py` — plus the sealed-artifact writer in
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`evals/deduction_serve/practice/runner.py`.
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## 1. Context
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Three capabilities had independently converged on the same four-step pattern:
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sealed practice writes a per-class tally table → the table is committed as a
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ratified artifact → serving verifies its `content_sha256` on load → a per-class
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gate decides SERVE against fixed ceilings.
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Three near-identical implementations is the point at which a shared component
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is an extraction rather than a guess. It matters now because the generalization
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plan puts a per-subject arena behind every new subject: without a bridge, each
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subject copies fifty lines of verification, and the copies drift.
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## 2. Decision
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`core/ratified_ledger.py` owns the mechanics — `seal_artifact`,
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`write_sealed_ledger`, `load_sealed_ledger`, `serve_license`, `tally_dict` —
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and states the four rules once:
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1. **The engine reads; only sealed practice writes.**
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2. **Tamper-evidence is structural** — a load that cannot reproduce
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`content_sha256` REFUSES. A hand-edited ledger is not a slightly-wrong
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ledger; it is an unratified one.
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3. **Ceilings are not negotiable at the call site** (ADR-0175 invariant #4).
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4. **Absent evidence is never a license** — a missing class yields `None`, and
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every caller's `None` branch serves the disclosed surface.
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Each capability keeps a thin adapter that names its artifact, keeps its
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memoization, and preserves its public API. One genuine difference is now
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declared rather than implied: `load_sealed_ledger(..., missing_ok=True)`
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distinguishes a ledger a capability *ships with* (absence = broken deployment,
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refuse) from one whose practice volume is still being built (absence = no class
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has earned anything, serve disclosed). Curriculum serving is the second kind
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today (ADR-0262 §5.1).
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## 3. Why this is safe
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The extraction's safety property is byte-identity: `seal_artifact` and
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`write_sealed_ledger` reproduce exactly what the bespoke sealers wrote, so
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re-sealing through the bridge leaves every committed artifact and every lane
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pin unmoved. That is asserted, not assumed —
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`test_committed_deduction_ledger_reseals_byte_identically` re-derives the
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committed 25-band ledger through the bridge and compares the bytes.
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## 4. What this unblocks
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A new subject arena now needs a gold corpus and a band key. It does not need to
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re-implement ratification — which is what the plan meant by "so each subject
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arena plugs in without bespoke wiring", and why §3 sequenced this ahead of the
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second subject.
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## 5. Scope-outs
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- **The estimation adapter keeps its predicate → converse-class naming.** That
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mapping is genuinely local to estimation; the bridge gates a class name and
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does not know how one is derived.
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- **No ledger migration.** All three artifacts already share the schema shape;
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nothing is rewritten, versioned, or moved.
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- **`core/learning_arena`'s practice engine is untouched.** The bridge covers
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the consumption half (seal → serve); the production half (run practice, tally)
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is already shared.
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## 6. Verification
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`tests/test_ratified_ledger_bridge.py` — 8 tests: round-trip, hand-edit
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rejection, required-vs-optional absence, absent class never licensed, the
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Wilson volume floor, a single `wrong` costing the license, committed-ledger
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byte-identity, and a guard that all three adapters read through the bridge
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(they no longer import a hashing module of their own). Plus the existing
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consumers unchanged: `core test --suite deductive` 252 passed; the estimation
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and license test set 355 passed.
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