---
title: "wasi-context — Mova code model"
description: "Mova code model of wasi-host/src/lib.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/wasi-host/src/lib.rs.groupant/wasi-context.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

This page as HTML: <https://groupants.elamur.ai/free/en/mova/wasi-host/src/lib.rs.groupant/wasi-context.groupant/>

# wasi-context

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

- **kind:** groupant_fragment
- **status:** partial source bound model
- **source:** [`wasi-host/src/lib.rs`](https://github.com/ElamurAI/mova-free/blob/main/wasi-host/src/lib.rs)
- **source SHA-256:** `91213ce903810791…`
- **covers:** Ctx starts stdio0..2 and preopen root3, empty env/input/output, fixed seed, 1000ns step and1024 fd cap. alloc_fd fills the first hole at index>=3 before checking vector length. at validates string then directory, rejects empty/absolute, otherwise joins base and relative path. (bytes 4771–9569)
- **part of:** [wasi-runtime](https://md.groupants.elamur.ai/free/en/mova/wasi-host/src/lib.rs.groupant/)
- **repository folder:** [`wasi-host/src/lib.rs.groupant/wasi-context.groupant`](https://github.com/ElamurAI/mova-free/tree/main/wasi-host/src/lib.rs.groupant/wasi-context.groupant)
- **repository commit:** `48f2e6f74146`

> **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](#approximant) |
| **ast** | partial | `../syntax.json` |
| **cost** | symbolic source derived | [invariant](#invariant) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant](#invariant) |
| **tests** | executed bounded checks | [tests](#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](#behavior-complement) |
| `reverse_reconstruction` | reverse_reconstruction | partial source derived model | [reverse_reconstruction](#reverse-reconstruction) |
| `descriptor_reuse` | descriptor_reuse | partial source derived model | [descriptor_reuse](#descriptor-reuse) |
| `seed_transition` | seed_transition | partial source derived model | [seed_transition](#seed-transition) |
| `capture_routing` | capture_routing | partial source derived model | [capture_routing](#capture-routing) |
| `path_precedence` | path_precedence | partial source derived model | [path_precedence](#path-precedence) |

## Model text


### descriptant

#### wasi-context

Ctx starts stdio0..2 and preopen root3, empty env/input/output, fixed seed, 1000ns step and1024 fd cap. alloc_fd fills the first hole at index>=3 before checking vector length. at validates string then directory, rejects empty/absolute, otherwise joins base and relative path.

##### 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

Ctx starts stdio0..2 and preopen root3, empty env/input/output, fixed seed, 1000ns step and1024 fd cap. alloc_fd fills the first hole at index>=3 before checking vector length. at validates string then directory, rejects empty/absolute, otherwise joins base and relative path.

Scope: `wasi-context`. 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

Ctx starts stdio0..2 and preopen root3, empty env/input/output, fixed seed, 1000ns step and1024 fd cap. alloc_fd fills the first hole at index>=3 before checking vector length. at validates string then directory, rejects empty/absolute, otherwise joins base and relative path.

The invariant is conditional on the admitted transition: alloc_fd cannot choose a later hole while an earlier eligible hole exists; absolute at cannot return a Vfs path. Emission does not promise successful host echo.

Cost: alloc_fd O(F), path clone/join O(path bytes), splitmix O(1), emit O(bytes) plus optional blocking host IO.

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-context`. 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: alloc_fd cannot choose a later hole while an earlier eligible hole exists; absolute at cannot return a Vfs path. Emission does not promise successful host echo.

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-context`. 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 given allocated descriptor fixes the first eligible vacant slot or prior vector length, not earlier close history. Captured stdout alone admits merged or unmerged histories when stderr was empty.

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.

### descriptor_reuse

Subject: `wasi-host/src/lib.rs` at SHA-256 `91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e`, scope `wasi-context`. 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: With max_fds=4 and live root, allocation returns MFILE; clearing slot3 permits reuse even at cap.

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.

### seed_transition

Subject: `wasi-host/src/lib.rs` at SHA-256 `91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e`, scope `wasi-context`. 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: splitmix state advances by wrapping additive constant, then two xor-shift wrapping multiplications; same state gives same next64 bits.

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.

### capture_routing

Subject: `wasi-host/src/lib.rs` at SHA-256 `91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e`, scope `wasi-context`. 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: err && !merge_stderr appends stderr, otherwise stdout; echo writes host stderr for err even if captured streams merge.

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.

### path_precedence

Subject: `wasi-host/src/lib.rs` at SHA-256 `91213ce9038107912c2dd707c3a6639a2d723cdfceb02981a166a6853800248e`, scope `wasi-context`. 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: Malformed UTF8 precedes BADF; non-directory precedes empty path; absolute path records denied Open before NOTCAPABLE.

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_memory_poll_and_descriptor_boundaries, tests::escape_and_absolute_paths_are_not_capable.

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.