ArghDA M1: Backend abstraction — make the engine prover-parametric#32
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The keystone refactor of the "Flying Logic for provers/solvers" epic.
Every Agda-baked seam now lives behind an object-safe `Backend` trait, so
the four-state workspace, DAG builder, content-hash invalidation and the
cycle-safe reachability walk are backend-neutral. Agda is the first (v0.1
reference) impl; adding Idris2/Lean4/Z3/CVC5/… now means an impl, not a
rewrite.
Behaviour is unchanged — this is the promised pure refactor with the test
suite as the oracle: the 64 pre-existing tests (50 lib + 14 integration)
all stay green, +2 new Agda-backend tests = 66 passing. clippy -D warnings,
fmt and the SPDX gate are clean; the `dag` JSON output is byte-compatible
and `check` still runs a real Agda typecheck.
New `src/prover/`:
- `Backend` trait: name/kind/extensions/safe_mode/check_file +
module_name_of/module_to_path/direct_imports/discover_roots/lint_rules.
- `BackendKind { Assistant, Solver }` — the two interaction models.
- `Verdict { Proven, Refuted, Unknown, Admitted, Postulated, Error,
Unavailable }` — the common verdict both models map into; only Proven is
green, Admitted/Postulated are amber.
- `Outcome` — superset of the old AgdaOutcome (raw process facts + kind +
verdict).
- `src/agda.rs` -> `src/prover/agda.rs` (Agda impl; owns the shell-out,
delegates parsing to `graph::` free fns and the lint pack to `lint::`).
Verdict is exit-code-only (0 -> Proven, ran-nonzero -> Error, absent ->
Unavailable) — arghda never claims a result Agda did not return;
Admitted/Postulated stay lint-derived, not manufactured from a green exit.
- `graph::build` and `dag::build` gain a `&dyn Backend` parameter and use
the backend's extension filter + import parsing; the reachability walk
and its cycle-termination regression are untouched.
- `main.rs` scan/check/dag/resolve_roots_and_rules route through the
backend; the `check` JSON key `agda` -> `backend` (now carries kind +
verdict).
- STATE.a2ml records M1 = 100%.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012MpYSh6Wy8YMBH2E3qVyT7
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…tion (#33) ## What & why The **headline capability** of the "Flying Logic for provers/solvers" epic, built on the M1 `Backend` trait (merged #32). A new `src/reason/` layer *wraps* (does not replace) the DAG: the `DagDocument` is embedded verbatim, and on top go a per-node `Verdict`, `And`/`Or` edge juncts, and a memoised, cycle-safe, **demote-only** propagation fold. ## The honesty invariant (enforced end-to-end) A node's effective verdict can only be **lowered** by its dependencies, never manufactured: - **lint-clean + no typecheck = `Unknown`**, never green. Only a real prover exit-0 makes `Proven`. - Only `Proven` is green; `Admitted`/`Postulated` are amber. - Because the fold is demote-only over `And` import edges, **structural amber infects downstream** — anything that transitively imports a `postulate` (or `missing-safe` / escape-hatch) module is itself capped. Visible *before any prover runs*. - `Or` groups are forgiving (one green route keeps a goal up). Import cycles degrade to `Error` and terminate. Staleness (closure-hash-changed `Proven` → `Unknown`) is applied pre-fold so it propagates. `wired` marks the CRT-root-reachable cone. ## Changes - `src/reason/mod.rs`: `Junct`, `ReasonNode` (`self_verdict`/`effective`/`verdict_evidence`/`soundness`/`wired`), `ReasonEdge`, `ReasonDocument` (`version:"0.1"`, embedded `dag`, `crt_roots`); the rank/demote/promote lattice; lint→verdict caps; the propagation fold. - `arghda reason <path> [--check]`: `--check` runs the backend per node for **real** exit-code verdicts; default is structure+lint-derived (all `unknown` on a clean tree, honestly). - `STATE.a2ml` records M3 = 100%. ## Verified (ran, not inferred) - `cargo test` → **81 passing, 0 failed** (61 lib + 20 integration; +9 reason unit tests covering demote / downstream-amber-infection / Or-forgiveness / cycle-termination / wiring / clean-but-unchecked→Unknown, +6 reason integration). - `cargo clippy -D warnings` clean · `cargo fmt --check` clean · `check-spdx.sh` OK. - **Dogfood** — `arghda reason tests/fixtures/wellformed --check` ran real `agda` typechecks → the whole cone `proven` + `wired`. ### A bug dogfooding caught (and I fixed) The first `--check` dogfood showed **every node `wired=false`** with `crt_roots=['tests.fixtures.wellformed.All']`. The CLI's `discover_roots` yields include-root-*relative* paths, which a stray `include_root.join` double-prefixed — so the CRT-root ids never matched the node ids. The unit/integration tests missed it because they passed *absolute* roots (where the join is a silent no-op). Fixed to match the orphan-module rule's convention (paths go straight to `module_name_of`), plus a regression test that exercises the `discover_roots` path. Re-dogfooded green. ## Next (all unblocked by the stable trait) M4 Idris2 · M5 SMT (Z3/CVC5) · M2 Cubical-Agda · M3 follow-on (feed real verdicts + staleness from a workspace `proven/` state so `reason` lights the cone without `--check`). --- _Generated by [Claude Code](https://claude.ai/code/session_012MpYSh6Wy8YMBH2E3qVyT7)_ Co-authored-by: Claude <noreply@anthropic.com>
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What & why
The keystone of the "Flying Logic for provers/solvers" epic. Every Agda-baked seam now lives behind an object-safe
Backendtrait, so the four-state workspace, DAG builder, content-hash invalidation and the cycle-safe reachability walk become backend-neutral. Agda is the first (v0.1 reference) impl; adding Idris2 / Lean4 / Z3 / CVC5 / Coq / Isabelle / Mizar is now an impl, not a rewrite.Follow-on from M0 (toolchain provisioning, merged as #31). #31 being merged, this is a fresh PR on the same working branch.
This is a pure refactor — the test suite is the oracle
Behaviour is unchanged, ground-truthed by running the tools (not inferred):
cargo test— the 64 pre-existing tests (50 lib + 14 integration) all stay green; +2 new Agda-backend tests = 66 passing, 0 failed.cargo clippy --all-targets --all-features -- -D warnings— clean.cargo fmt --check— clean.scripts/check-spdx.sh .—SPDX licence invariant: OK.arghda dag tests/fixtures/wellformedemits byte-compatible JSON (version: "0.1", same nodes/edges);arghda check …/All.agdaran a real Agda typecheck →proven-eligible(agda is present from ArghDA → Flying Logic for provers/solvers: M0 (toolchain provisioning + doctor) #31's provisioning).Changes
New
src/prover/:Backendtrait —name/kind/extensions/safe_mode/check_file+ the import-graph trio (module_name_of/module_to_path/direct_imports) +discover_roots+lint_rules.BackendKind { Assistant, Solver }— the two interaction models (typecheck-a-file vs SMT query).Verdict { Proven, Refuted, Unknown, Admitted, Postulated, Error, Unavailable }— the common verdict both models map into. OnlyProvenis green;Admitted/Postulatedare amber.Outcome— superset of the oldAgdaOutcome(raw process facts +kind+verdict).Refactor:
src/agda.rs→src/prover/agda.rs.Agdais the first impl: owns theagdashell-out, delegates parsing tograph::free fns and the lint pack tolint::. Verdict is exit-code-only (0 →Proven, ran-nonzero →Error, absent →Unavailable) — arghda never claims a result Agda did not return;Admitted/Postulatedstay lint-derived, never manufactured from a green exit.graph::buildanddag::buildtake&dyn Backendand use the backend's extension filter + import parsing. The cycle-safe reachability walk and itstransitive_imports_terminates_on_a_cycleregression are untouched — cycle safety is inherited free by every backend.main.rsscan/check/dag/resolve_roots_and_rulesroute through the backend; thecheckJSON keyagda→backend(now carrieskind+verdict).STATE.a2mlrecords M1 = 100%;.gitignoreignores*.agdai.Honesty note (owner directive + AGENTIC.a2ml)
The
Backendmodule is the boundary where "never report a verdict the tool did not emit" is enforced:check_filederives its verdict from the actual exit code and degrades toUnavailablewhen the binary is absent.Next (trait now stable → parallelisable)
M3 reasoning-graph (
src/reason), M4 Idris2, M5 SMT (Z3/CVC5), M2 Cubical-Agda.Generated by Claude Code