---
title: "db-src-tsv-row-write — Mova code model"
description: "Mova code model of tools/db/src/tsv.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/tools/db/src/tsv.rs.groupant/row-write.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**

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# db-src-tsv-row-write

The groupant beside tools/db/src/tsv.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:** [`tools/db/src/tsv.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/db/src/tsv.rs)
- **source SHA-256:** `ae03009ea628e1b4…`
- **covers:** TSV row prefix and counter transition (bytes 1209–2197)
- **part of:** [db-src-tsv](https://md.groupants.elamur.ai/free/en/mova/tools/db/src/tsv.rs.groupant/)
- **repository folder:** [`tools/db/src/tsv.rs.groupant/row-write.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/db/src/tsv.rs.groupant/row-write.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** | partial | [invariant-and-cost](#invariant-and-cost) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant-and-cost](#invariant-and-cost) |
| **tests** | bounded checks partial scope | [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) |
| `write_frontier` | write_frontier | partial source derived model | [write_frontier](#write-frontier) |
| `null_sentinel` | null_sentinel | partial source derived model | [null_sentinel](#null-sentinel) |
| `boolean_encoding` | boolean_encoding | partial source derived model | [boolean_encoding](#boolean-encoding) |
| `counter_failure_order` | counter_failure_order | partial source derived model | [counter_failure_order](#counter-failure-order) |

## Model text


### descriptant

#### TSV row prefix and counter transition

Validate arity; for each cell write separator then encoded value; string validation occurs after separator. On all-success append LF then rows+=1; propagate first IO or value error.

##### Prospective epoch — 2026-10-31

Full source was reviewed before edits; external prospective.md records API states, failure order and predicted checks. Production prefix remains byte-identical; test additions are isolated cfg(test)/test items.

##### Observed epoch — 2026-10-31

2026-10-31 wave31: 16 selected target/name cases passed twice debug and twice release with identical sorted outcomes; six compiled source-behavior mutants failed assertions, exact bytes restored and positive checks passed. Evidence scope is only the named helpers/fixtures. External receipt directory: $MOVA_DATA/runs/octopus-wave31-store-2026-10-31. No DuckDB integration, production loader/corpus, training or GPU run.

##### Retained limitations

No SQL evaluation was substituted with a mock process. Missing DuckDB is a dependency gap, not passing database evidence. Partial syntax has no macro expansion/name resolution/types; Rust helpers and fixtures do not prove all models.

### approximant

#### TSV row prefix and counter transition forward relation

Validate arity; for each cell write separator then encoded value; string validation occurs after separator. On all-success append LF then rows+=1; propagate first IO or value error.

##### Domain

Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

##### Approximation limits

Categorical parsing, exact identity, transactional effects and resource errors have no useful percentage approximation metric here. No executable surrogate is claimed. Future profiles, if justified, may use only 1%, 2%, 5%, 10% with a defined metric/reference/domain.

### models

## TSV row prefix and counter transition typed model catalog

Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Observation is one call/trace in the declared scope. Operators below are partial source-derived relations; complement is a proposed inner exclusion relation, reverse an outer compatible-antecedent relation retaining ambiguity. No universal proof follows from finite checks. Each oracle is the relevant named helper check below when it reaches the behavior; remaining SQL/effect cases are source review or proposed real-CLI checks.

### behavior_complement

Wrong width cannot change row bytes. Invalid string cannot increment rows, but absence of partial bytes is not guaranteed.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### reverse_reconstruction

Given encoded complete row, string-vs-I-vs-B antecedents can be ambiguous. Given failed prefix, compatible offending cells include every forbidden string at that column plus IO failures.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### write_frontier

For second invalid cell, first cell and TAB precede failure. Synthetic fixture asserts exact prefix after flush.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### null_sentinel

Only V::Null can successfully emit exact backslash-N. V::S sentinel rejected to preserve null distinction.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### boolean_encoding

V::B true/false emits lowercase literals without quotes; integer formatting uses signed decimal, strings preserve valid bytes.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### counter_failure_order

rows increments after newline write, so IO failure before/at newline leaves count unchanged. Allocation and IO fault injection remain untested.

Domain/assumptions: Finite valid-UTF8 inputs, representable counters/IDs, available memory; filesystem fixtures confined to owned temporary root. SQL semantics are conditional and unexecuted. Subject is the source and SHA256 bound in manifest; fragment applies only to declared byte range.

Evidence: see tests.md; unexecuted database branches remain conditional.

### tests

#### Selected checks

2026-10-31 wave31: 16 selected target/name cases passed twice debug and twice release with identical sorted outcomes; six compiled source-behavior mutants failed assertions, exact bytes restored and positive checks passed. Evidence scope is only the named helpers/fixtures. External receipt directory: $MOVA_DATA/runs/octopus-wave31-store-2026-10-31. No DuckDB integration, production loader/corpus, training or GPU run.

Named target-scoped checks for parent source: ["tsv::wave31::actual_tsv_null_empty_and_numeric_boundaries","tsv::wave31::rejected_rows_preserve_counter_but_may_write_prefix"]

Native commands and numeric status/log/outcomes live in external native-commands.json and receipts. Integration fixture checks use actual en::conllu parsing only. Legacy prag_layer_and_negative_controls, qa_table_loader_and_negative_controls and lossless_round_trip_and_negative_controls were inspected but not executed: real DuckDB unavailable. A fragment's listed parent tests may only cover part of its relation; SQL/query/transaction/IO-fault claims remain source-derived.

##### Negative controls

Six source-behavior mutations: quote doubling, TSV NULL rejection, QA positivity, prag bit truth, MWT counter, sentence boundary predicate. Each compiled, failed an assertion, restored exact original bytes and passed the selected positive. No assertion-only mutations and no surviving behavioral mutants.

### invariant-and-cost

#### TSV row prefix and counter transition invariants and costs

##### Invariant

Counter delta is1 only after successful newline. A failed row may leave prior cells/separator physically buffered; caller must discard failed stage rather than reuse as a valid table.

##### Cost

O(encoded row bytes) write work; no prevalidation copy; buffer bounded apart from formatting/error preview.

Symbolic bounds are source-derived, not measured wall-clock speed or universal complexity proof. Allocation failures, integer exhaustion and concurrency are outside finite evidence.