Elamur Groupantsvfs-api-limits
The groupant beside vfs/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 |
| composition | partial | composition |
| cost | partial | Cost |
| 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 |
parse_order | parse_order | partial source derived model | parse_order |
duplicates | duplicates | partial source derived model | duplicates |
units | units | partial source derived model | units |
empty_input | empty_input | partial source derived model | empty_input |
Model text
descriptant
vfs-api-limits
Limit parsing and binary suffix arithmetic.
Prospective epoch
2026-10-31: source reviewed before edits; prospective review retained under $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31/prospective.md. Predicted order/cost: O(input bytes), constant fields.
Observation epoch
Bounded actual calls and compiled negative controls are recorded in tests.md. Production behavior bytes unchanged; only focused test blocks added. Snapshot constant-time wording is conditional on cwd and destruction; recursive operations may partially commit.
Unsupported approximants
No executable percentage surrogate is claimed for these categorical/state/effect observations. Future 1%,2%,5%,10% require a useful metric, explicit domain and exact reference.
approximant
Forward relation
Limit parsing and binary suffix arithmetic.
Fold comma-separated nonempty assignments over defaults; parse_size trim and checked multiply; dispatch key only after successful number parse.
Domain: bounded inputs with available allocation and nonoverflowing counters unless checked explicitly. The relation is partial and source-derived.
composition
Composition
Limit parsing and binary suffix arithmetic. Shared state and order: Fold comma-separated nonempty assignments over defaults; parse_size trim and checked multiply; dispatch key only after successful number parse.
Scoped children project this same source. Their domains and effects remain conditional; source execution connects these clauses rather than independently proving their wiring. Last duplicate wins; zero allowed; max u64 multiplication checked.
models
Typed source models
Source-bound partial relations; no universal finite-test proof.
behavior_complement
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Unknown key cannot be accepted; overflow cannot wrap.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
reverse_reconstruction
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Limits output admits redundant defaults, casing and overwritten earlier assignments.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
parse_order
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Malformed number wins before unknown key error.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
duplicates
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Repeated file assignments choose latest successfully parsed value.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
units
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: K/M/G case-insensitive powers1024, no decimal SI.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
empty_input
Subject: vfs-api-limits. Domain: Limit parsing and binary suffix arithmetic. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Empty comma segments keep defaults; empty size itself fails.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
tests
Checks and limitations
Exact named observations: wave31::parsing_and_trait_composition, limits_parse.
Fresh receipts: $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31; run.sh retains four profile/repetition sets with raw logs and numeric statuses. native-commands.json and source-test-map.json disambiguate targets. Compiled mutations and exact restoration are separately retained in mutation-summary.json.
These finite observations are not semantic completeness. Source syntax generated twice and compared byte-for-byte. Host effects are limited to owned TMPDIR fixtures. Existing absolute_paths_never_reach_the_host and open_modes are skipped; snapbench main is skipped. Standalone helpers/reexports are only observed through named callers or representation checks; RealFs effect methods unexecuted.
invariant-and-cost
Invariant and cost
Invariant
Last duplicate wins; zero allowed; max u64 multiplication checked.
Cost
O(input bytes), constant fields.
No timing or numerical error guarantee is inferred from finite tests.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/vfs/src/lib.rs.groupant/limits.groupant/