Elamur Groupantswasi-engine
The groupant beside wasi-host/src/lib.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 | partial | approximant |
| ast | partial | ../syntax.json |
| cost | symbolic source derived | invariant |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | tests |
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 |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
fresh_context | fresh_context | partial source derived model | fresh_context |
import_name_filter | import_name_filter | partial source derived model | import_name_filter |
entry_requirement | entry_requirement | partial source derived model | entry_requirement |
fuel_observation | fuel_observation | partial source derived model | fuel_observation |
Model text
descriptant
wasi-engine
new configures fuel only when Some, validates Module and binds WASI. run creates Store with Ctx limits, sets optional fuel, instantiates/starts module then calls typed _start. Return success0, i32 exit preserved without trap, other error134 with text; fuel used=ceiling-remaining.
Epoch 2026-10-31
Prospective review recorded before edits. Source review found late output FAULT effects and weaker-than-capability rights metadata; these are modeled as current behavior rather than silently repaired. Only bounded new test blocks were added; production code remains unchanged. Actual finite results and exact restoration receipts live under $MOVA_DATA/runs/octopus-wave31-wasi-2026-10-31. No full mlab guest, frozen suite, GPU or corpus run. This node retains its scoped observations for future refinement.
approximant
Forward relation
new configures fuel only when Some, validates Module and binds WASI. run creates Store with Ctx limits, sets optional fuel, instantiates/starts module then calls typed _start. Return success0, i32 exit preserved without trap, other error134 with text; fuel used=ceiling-remaining.
Scope: wasi-engine. State and transitions follow the authoritative source, including partial effects before errors. No executable approximate replacement is attached: categorical errno/effects and module execution lack a useful validated percentage metric; future numerical profiles may only use1/2/5/10% caps after domain/reference evidence.
invariant
Invariant and cost
new configures fuel only when Some, validates Module and binds WASI. run creates Store with Ctx limits, sets optional fuel, instantiates/starts module then calls typed _start. Return success0, i32 exit preserved without trap, other error134 with text; fuel used=ceiling-remaining.
The invariant is conditional on the admitted transition: A non-exit engine error cannot yield trap=None; a normal return cannot yield134. Named allowed imports do not exclude signature mismatches.
Cost: Module-dependent validation and interpreter cost; optional fuel constrains instructions only, Store memory separate; per-run instance allocation.
No wall-time gain, universal resource bound or atomic rollback is inferred. External Vfs/wasmi/native-mlab work remains separately charged.
models
Typed model catalog
behavior_complement
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: A non-exit engine error cannot yield trap=None; a normal return cannot yield134. Named allowed imports do not exclude signature mismatches.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
reverse_reconstruction
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Successful exit0 can arise from normal return or proc_exit(0); trap134 admits validation-compatible modules failing at instantiate/start/call. Missing imports list cannot recover type mismatches.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
fresh_context
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Host shares compiled module/linker but each run gets fresh Store and supplied Ctx, not previous memory.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
import_name_filter
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: missing_imports tests namespace/name membership only; known name with wrong signature still fails linking.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
entry_requirement
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: Valid module lacking compatible exported _start becomes run error134, not Host::new error.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
fuel_observation
Subject: wasi-host/src/lib.rs at SHA-256 91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e, scope wasi-engine. Domain: the source transition and bounded fixtures described in approximant.md; readable valid host resources where required. Observation: returned values, byte coordinates, state/effect order, not total-system semantics. Operator/relation: None produces no fuel_used; Some reports consumed instructions even on trap, not elapsed time or all host work.
Status: partial source-derived relation; complement is a scoped exclusion hypothesis, reverse preserves all compatible antecedents described rather than a chosen inverse. Assumptions: production branch order, declared coordinate/resource premises; no completeness claim for untested inputs. Evidence: tests.md distinguishes actual execution from source review; finite observations can falsify but not prove the relation.
tests
Checks and limits
Named actual-source tests run twice per debug/release; exact commands and numeric statuses retained externally. Test success is finite evidence only.
Exact names: tests::wave31_tiny_engine_outcomes.
Memory tests bypass linker ABI; tiny empty/unreachable guests exercise engine outcomes only. The CLI test uses isolated import/export/journal fixtures.
Five compiled production/helper-source controls: append offset, virtual clock advance, trap status, CLI export gate and newest-mtime max. Each compiles, fails its selected assertion, restores exact original bytes and passes again. These controls cover their target relations, not every node. No assertion-only mutants. See external source-test-map.json, native-commands.json, verify.rs and numeric/raw receipts in $MOVA_DATA/runs/octopus-wave31-wasi-2026-10-31. The example main and frozen mlab paths are never executed.
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