fix(connectors): retain exact CSV source evidence

Release v0.1.27. Coordinated integrity review: GovOPlaN/govoplan-core#298.

src/govoplan_connectors/backend/db/models.py

@@ -47,6 +47,8 @@ class ConnectorTabularSource(Base, TimestampMixin):
     row_count: Mapped[int] = mapped_column(Integer, nullable=False)
     byte_count: Mapped[int] = mapped_column(Integer, nullable=False)
     metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSON, default=dict, nullable=False)
+    # Original upload content is deliberately excluded from ordinary catalogue loads/DTOs.
+    csv_source_: Mapped[dict[str, Any] | None] = mapped_column("csv_source", JSON, nullable=True, deferred=True)
     created_by: Mapped[str | None] = mapped_column(String(255), nullable=True, index=True)
     updated_by: Mapped[str | None] = mapped_column(String(255), nullable=True, index=True)
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)

src/govoplan_connectors/backend/german_documentation.py

@@ -1,9 +1,8 @@
 from __future__ import annotations
 
-from dataclasses import replace
 from typing import Iterable
 
-from govoplan_core.core.modules import DocumentationTopic
+from govoplan_core.core.modules import DocumentationTopic, localize_documentation_topics as _localize_topics
 
 
 _TRANSLATIONS = {
@@ -64,15 +63,4 @@ _TRANSLATIONS = {
 def localize_documentation_topics(
     topics: Iterable[DocumentationTopic],
 ) -> tuple[DocumentationTopic, ...]:
-    localized: list[DocumentationTopic] = []
-    for topic in topics:
-        german = _TRANSLATIONS.get(topic.id)
-        if german is None:
-            localized.append(topic)
-            continue
-        translations = {
-            locale: dict(value) for locale, value in topic.translations.items()
-        }
-        translations["de"] = {**translations.get("de", {}), **german}
-        localized.append(replace(topic, translations=translations))
-    return tuple(localized)
+    return _localize_topics(topics, locale="de", translations=_TRANSLATIONS)

src/govoplan_connectors/backend/knowledge_search.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from govoplan_connectors.backend.search_principal import principal_acl_tokens as _principal_acl_tokens
+
 from collections.abc import Mapping, Sequence
 from urllib.parse import quote
 
@@ -217,30 +219,6 @@ def search_document(
     )
 
 
-def _principal_acl_tokens(principal: object) -> tuple[str, ...]:
-    values: list[str] = []
-    for prefix, attribute in (
-        ("account", "account_id"),
-        ("membership", "membership_id"),
-        ("identity", "identity_id"),
-    ):
-        value = getattr(principal, attribute, None)
-        if value:
-            values.append(f"{prefix}:{value}")
-    for prefix, attribute in (
-        ("group", "group_ids"),
-        ("role", "role_ids"),
-        ("function", "function_assignment_ids"),
-        ("scope", "scopes"),
-    ):
-        values.extend(
-            f"{prefix}:{value}"
-            for value in getattr(principal, attribute, ())
-            if value
-        )
-    return tuple(dict.fromkeys(values))[:500]
-
-
 def _has_scope(principal: object, required: str) -> bool:
     check = getattr(principal, "has", None)
     if callable(check):

src/govoplan_connectors/backend/manifest.py

@@ -126,7 +126,7 @@ from govoplan_connectors.backend.german_documentation import (
 
 
 MODULE_ID = "connectors"
-MODULE_VERSION = "0.1.26"
+MODULE_VERSION = "0.1.27"
 TABULAR_SOURCE_INTERFACE_VERSION = "0.1.0"
 DATASOURCE_ORIGIN_INTERFACE_VERSION = "0.1.0"
 SANCTIONS_SNAPSHOT_INTERFACE_VERSION = "1.0.0"
@@ -967,6 +967,38 @@ manifest = ModuleManifest(
         ),
     ),
     documentation=localize_documentation_topics((
+        DocumentationTopic(
+            id="connectors.csv-source-fidelity",
+            title="Preserving original CSV input",
+            summary="Choose explicit text or legacy type inference, and retrieve the verified original of new CSV snapshots.",
+            body=(
+                "CSV snapshot and managed-file creation accept csv_value_mode=text to preserve field whitespace, decimal digits, large identifiers, boolean-looking text and explicit empty records as strings. "
+                "Text mode rejects missing/extra fields and malformed quoting rather than dropping values. Headers remain normalized and blank physical lines are not table rows; the original upload preserves these lexical details. "
+                "Omitting csv_value_mode keeps legacy_typed API behavior for existing clients. Legacy inference can trim values, infer numbers/booleans and omit empty rows; choose text when exact values matter. "
+                "New CSV snapshots retain the original supplied text, delimiter, parser profile and UTF-8 SHA-256 separately from catalogue responses; csv_source metadata is reserved verified evidence, not a place to supply content. "
+                "GET /api/v1/connectors/tabular-sources/{source_ref}/original-csv requires current connectors:source:read or connectors:source:admin authority in the same tenant, verifies the checksum, audits the export without source content, and returns an uncached attachment. "
+                "The export preserves the text submitted to the API as UTF-8, not an earlier file encoding. It does not sanitize spreadsheet formulas: treat imported originals as untrusted data. "
+                "Original text and parsed rows each remain limited to 5 MB, with at most 10,000 parsed rows. Each snapshot can retain up to 5 MB of original text, plus serialization and metadata storage overhead. Source text follows the snapshot lifecycle; retired/deleted sources are not downloadable. "
+                "Managed files retain their original through the exact Files version and its access/lifecycle policy; text mode is pinned in source metadata and preserved on refresh. Existing snapshot fingerprints and historical rows are never rewritten. "
+                "Original text cannot be reconstructed for older snapshots: the endpoint reports it unavailable. Schema inference now shares one ordered, bounded-state mechanism with Datasources while preserving legacy provider type classifications."
+            ),
+            layer="always", documentation_types=("user", "admin"), audience=("user", "module_admin", "operator"), order=8,
+            translations={"de": {
+                "title": "Ursprüngliche CSV-Eingaben erhalten",
+                "summary": "Textwerte oder bisherige Typableitung ausdrücklich wählen und das geprüfte Original neuer CSV-Snapshots abrufen.",
+                "body": (
+                    "CSV-Snapshots und verwaltete Dateiquellen unterstützen csv_value_mode=text. Dieser Modus erhält Leerzeichen in Feldwerten, Dezimalstellen, große Kennungen, boolesch wirkenden Text und ausdrücklich leere Datensätze als Zeichenketten. "
+                    "Fehlende oder zusätzliche Felder und fehlerhafte Anführungszeichen werden abgelehnt. Überschriften werden weiterhin normalisiert; vollständig leere physische Zeilen sind keine Tabellenzeilen. Das Original erhält auch diese Texteigenschaften. "
+                    "Ohne csv_value_mode bleibt für bestehende API-Aufrufe legacy_typed aktiv. Dabei können Werte gekürzt, Zahlen/Wahrheitswerte abgeleitet und leere Zeilen ausgelassen werden. Für genaue Werte wählen Sie Text. "
+                    "Neue CSV-Snapshots speichern den gelieferten Originaltext, Trennzeichen, Parserprofil und UTF-8-SHA-256 getrennt vom Katalog. csv_source-Metadaten sind reservierter geprüfter Nachweis. "
+                    "GET /api/v1/connectors/tabular-sources/{source_ref}/original-csv benötigt aktuelle Rechte connectors:source:read oder connectors:source:admin im selben Mandanten, prüft die Prüfsumme, protokolliert den Export ohne Quellinhalt und liefert einen nicht zwischengespeicherten Download. "
+                    "Exportiert wird der an die API übermittelte Text als UTF-8, nicht eine frühere Dateikodierung. Tabellenformeln werden nicht verändert; behandeln Sie Originaldateien als nicht vertrauenswürdige Daten. "
+                    "Originaltext und verarbeitete Zeilen sind jeweils auf 5 MB begrenzt; höchstens 10.000 Zeilen werden angenommen. Pro Snapshot werden bis zu 5 MB Originaltext zuzüglich Speicher für Serialisierung und Metadaten aufbewahrt. Der Originaltext folgt dem Snapshot-Lebenszyklus; stillgelegte oder gelöschte Quellen sind nicht abrufbar. "
+                    "Verwaltete Dateien behalten ihr Original in der genauen Files-Version mit deren Zugriffs- und Lebenszyklusregeln; der Textmodus bleibt bei Aktualisierungen erhalten. Bestehende Fingerprints und historische Zeilen werden nicht umgeschrieben. "
+                    "Für ältere Snapshots kann das Original nicht rekonstruiert werden; der Abruf meldet es als nicht verfügbar. Die gemeinsame Schemaableitung erhält die bisherigen Typregeln und Spaltenreihenfolge."
+                ),
+            }},
+        ),
         DocumentationTopic(
             id="connectors.data-subject-requests",
             title="Connector data-subject requests",

src/govoplan_connectors/backend/migrations/versions/d2a4c6e8f0b1_csv_source_evidence.py

@@ -0,0 +1,20 @@
+"""Retain original CSV source evidence for new durable snapshots."""
+
+from alembic import op
+import sqlalchemy as sa
+
+revision = "d2a4c6e8f0b1"
+down_revision = "c0f1a2b3c4d5"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "connector_tabular_sources", sa.Column("csv_source", sa.JSON(), nullable=True)
+    )
+
+
+def downgrade() -> None:
+    with op.batch_alter_table("connector_tabular_sources") as batch:
+        batch.drop_column("csv_source")

src/govoplan_connectors/backend/router.py

@@ -10,6 +10,7 @@ from sqlalchemy.orm import Session
 from govoplan_core.audit.logging import audit_event
 from govoplan_core.auth import ApiPrincipal, get_api_principal, has_scope
 from govoplan_core.core.tabular_sources import (
+    TabularCsvSource,
     TabularReadRequest,
     TabularSnapshotInput,
     TabularSource,
@@ -539,7 +540,7 @@ def api_create_tabular_snapshot(
         rows = (
             tuple(payload.rows or ())
             if payload.format == "json"
-            else parse_csv_snapshot(payload.csv_text or "", delimiter=payload.delimiter)
+            else parse_csv_snapshot(payload.csv_text or "", delimiter=payload.delimiter, value_mode=payload.csv_value_mode)
         )
         source = provider.create_snapshot(
             session,
@@ -550,6 +551,11 @@ def api_create_tabular_snapshot(
                 description=payload.description,
                 rows=rows,
                 metadata={"import_format": payload.format},
+                csv_source=(TabularCsvSource(
+                    text=payload.csv_text or "",
+                    delimiter=payload.delimiter,
+                    value_mode=payload.csv_value_mode,
+                ) if payload.format == "csv" else None),
             ),
         )
     except TabularSourceError as exc:
@@ -573,6 +579,35 @@ def api_create_tabular_snapshot(
     return _source_response(source)
 
 
+@router.get("/tabular-sources/{source_ref}/original-csv")
+def api_original_tabular_csv(
+    source_ref: str,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> Response:
+    _require_any_scope(principal, READ_SCOPE, ADMIN_SCOPE)
+    try:
+        text = provider.original_csv(session, principal, source_ref=source_ref)
+    except TabularSourceError as exc:
+        raise _http_error(exc) from exc
+    audit_event(
+        session,
+        tenant_id=principal.tenant_id,
+        user_id=getattr(principal.user, "id", None),
+        api_key_id=principal.api_key_id,
+        action="connectors.original_csv.exported",
+        object_type="connector_tabular_source",
+        object_id=source_ref,
+        details={"sha256": hashlib.sha256(text.encode("utf-8")).hexdigest()},
+    )
+    session.commit()
+    return Response(
+        content=text.encode("utf-8"),
+        media_type="text/csv; charset=utf-8",
+        headers={"Content-Disposition": 'attachment; filename="original.csv"', "Cache-Control": "no-store"},
+    )
+
+
 @router.post(
     "/tabular-sources/files",
     response_model=TabularSourceResponse,
@@ -595,6 +630,7 @@ def api_create_managed_file_source(
             file_version_id=payload.file_version_id,
             delimiter=payload.delimiter,
             sheet_name=payload.sheet_name,
+            csv_value_mode=payload.csv_value_mode,
         )
     except TabularSourceError as exc:
         raise _http_error(exc) from exc

src/govoplan_connectors/backend/schemas.py

@@ -90,6 +90,7 @@ class SnapshotCreateRequest(BaseModel):
     format: Literal["json", "csv"] = "json"
     rows: list[dict[str, Any]] | None = Field(default=None, max_length=10_000)
     csv_text: str | None = Field(default=None, max_length=5_000_000)
+    csv_value_mode: Literal["legacy_typed", "text"] = "legacy_typed"
     delimiter: Literal[",", ";", "\t", "|"] = ","
 
     @model_validator(mode="after")
@@ -117,6 +118,7 @@ class ManagedFileSourceCreateRequest(BaseModel):
     file_version_id: str | None = Field(default=None, min_length=1, max_length=36)
     delimiter: Literal[",", ";", "\t", "|"] = ","
     sheet_name: str | None = Field(default=None, min_length=1, max_length=255)
+    csv_value_mode: Literal["legacy_typed", "text"] = "legacy_typed"
 
 
 class SqlSourceCreateRequest(BaseModel):

src/govoplan_connectors/backend/search_principal.py

@@ -0,0 +1,26 @@
+"""Shared connector-search ACL token projection; owner authorization stays local."""
+
+
+def principal_acl_tokens(principal: object) -> tuple[str, ...]:
+    # Keep legacy first-seen ordering and the exact 500-token authorization cap.
+    values: dict[str, None] = {}
+    for prefix, attribute in (
+        ("account", "account_id"),
+        ("membership", "membership_id"),
+        ("identity", "identity_id"),
+    ):
+        value = getattr(principal, attribute, None)
+        if value:
+            values[f"{prefix}:{value}"] = None
+    for prefix, attribute in (
+        ("group", "group_ids"),
+        ("role", "role_ids"),
+        ("function", "function_assignment_ids"),
+        ("scope", "scopes"),
+    ):
+        for value in getattr(principal, attribute, ()):
+            if value:
+                values[f"{prefix}:{value}"] = None
+                if len(values) >= 500:
+                    return tuple(values)
+    return tuple(values)

src/govoplan_connectors/backend/service_desk_search.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from govoplan_connectors.backend.search_principal import principal_acl_tokens as _principal_acl_tokens
+
 from collections.abc import Mapping, Sequence
 from urllib.parse import quote
 
@@ -288,30 +290,6 @@ def search_document(
     )
 
 
-def _principal_acl_tokens(principal: object) -> tuple[str, ...]:
-    values: list[str] = []
-    for prefix, attribute in (
-        ("account", "account_id"),
-        ("membership", "membership_id"),
-        ("identity", "identity_id"),
-    ):
-        value = getattr(principal, attribute, None)
-        if value:
-            values.append(f"{prefix}:{value}")
-    for prefix, attribute in (
-        ("group", "group_ids"),
-        ("role", "role_ids"),
-        ("function", "function_assignment_ids"),
-        ("scope", "scopes"),
-    ):
-        values.extend(
-            f"{prefix}:{value}"
-            for value in getattr(principal, attribute, ())
-            if value
-        )
-    return tuple(dict.fromkeys(values))[:500]
-
-
 def _has_scope(principal: object, required: str) -> bool:
     check = getattr(principal, "has", None)
     if callable(check):

src/govoplan_connectors/backend/tabular_adapters.py

@@ -53,6 +53,9 @@ from govoplan_core.core.tabular_sources import (
     TabularSourceUnavailableError,
     TabularSourceValidationError,
     parse_tabular_csv,
+    CsvValueMode,
+    infer_tabular_schema as _infer_schema,
+    tabular_type_name,
 )
 from govoplan_core.security.credential_envelopes import (
     CredentialAccessContext,
@@ -125,6 +128,7 @@ class ManagedFileTabularAdapter:
         file_version_id: str | None,
         delimiter: str = ",",
         sheet_name: str | None = None,
+        csv_value_mode: CsvValueMode = "legacy_typed",
     ) -> TabularOriginInspection:
         provider = managed_tabular_file_provider(self._registry)
         if provider is None:
@@ -163,6 +167,7 @@ class ManagedFileTabularAdapter:
             content_type=content.file.content_type,
             delimiter=delimiter,
             sheet_name=sheet_name,
+            csv_value_mode=csv_value_mode,
         )
         schema = infer_tabular_schema(rows)
         fingerprint = origin_fingerprint(
@@ -174,6 +179,7 @@ class ManagedFileTabularAdapter:
                 content.file.sha256,
                 resolved_sheet or "",
                 delimiter,
+                *(("csv_text_values",) if csv_value_mode == "text" else ()),
             ),
         )
         try:
@@ -227,6 +233,7 @@ class ManagedFileTabularAdapter:
                 "content_type": content.file.content_type,
                 "format": "xlsx" if _is_xlsx(content.file.filename, content.file.content_type) else "csv",
                 "delimiter": delimiter,
+                "csv_value_mode": csv_value_mode,
                 "sheet_name": resolved_sheet,
             },
             health=health,
@@ -263,6 +270,7 @@ class ManagedFileTabularAdapter:
             file_version_id=_required_metadata(metadata, "file_version_id"),
             delimiter=str(metadata.get("delimiter") or ","),
             sheet_name=_optional_text(metadata.get("sheet_name")),
+            csv_value_mode=str(metadata.get("csv_value_mode") or "legacy_typed"),
         )
         expected_sha256 = _required_metadata(metadata, "file_sha256")
         if inspection.metadata.get("file_sha256") != expected_sha256:
@@ -567,6 +575,7 @@ def parse_managed_tabular_content(
     content_type: str | None,
     delimiter: str,
     sheet_name: str | None,
+    csv_value_mode: CsvValueMode = "legacy_typed",
 ) -> tuple[tuple[Mapping[str, object], ...], str | None]:
     if len(payload) > MAX_FILE_BYTES:
         raise TabularSourceValidationError(
@@ -581,7 +590,7 @@ def parse_managed_tabular_content(
             "Managed CSV files must use UTF-8 encoding."
         ) from exc
     return (
-        tuple(parse_tabular_csv(text, delimiter=delimiter, max_rows=MAX_FILE_ROWS)),
+        tuple(parse_tabular_csv(text, delimiter=delimiter, max_rows=MAX_FILE_ROWS, max_bytes=MAX_FILE_BYTES, value_mode=csv_value_mode)),
         None,
     )
 
@@ -809,26 +818,7 @@ def _xlsx_headers(values: Sequence[object]) -> tuple[str, ...]:
 def infer_tabular_schema(
     rows: Sequence[Mapping[str, object]],
 ) -> tuple[TabularColumn, ...]:
-    names: list[str] = []
-    for row in rows:
-        for name in row:
-            if name not in names:
-                names.append(name)
-    result: list[TabularColumn] = []
-    for name in names:
-        values = [row.get(name) for row in rows]
-        concrete = [value for value in values if value is not None]
-        data_type = _type_name(concrete[0]) if concrete else "unknown"
-        if any(_type_name(value) != data_type for value in concrete[1:]):
-            data_type = "mixed"
-        result.append(
-            TabularColumn(
-                name=name,
-                data_type=data_type,
-                nullable=len(concrete) != len(values),
-            )
-        )
-    return tuple(result)
+    return _infer_schema(rows, type_name=_type_name)
 
 
 def origin_fingerprint(
@@ -951,19 +941,7 @@ def _json_value(value: object) -> object:
 
 
 def _type_name(value: object) -> str:
-    if isinstance(value, bool):
-        return "boolean"
-    if isinstance(value, int):
-        return "integer"
-    if isinstance(value, (float, Decimal)):
-        return "number"
-    if isinstance(value, str):
-        return "string"
-    if isinstance(value, list):
-        return "array"
-    if isinstance(value, dict):
-        return "object"
-    return type(value).__name__.casefold()
+    return tabular_type_name(value, casefold_unknown=True)
 
 
 __all__ = [

src/govoplan_connectors/backend/tabular_sources.py

@@ -13,6 +13,7 @@ from sqlalchemy.orm import Session
 
 from govoplan_core.auth import ApiPrincipal, has_scope
 from govoplan_core.core.tabular_sources import (
+    CsvValueMode,
     TabularColumn,
     TabularPreviewDiagnostic,
     TabularPushdown,
@@ -26,6 +27,12 @@ from govoplan_core.core.tabular_sources import (
     TabularSourceUnavailableError,
     TabularSourceValidationError,
     parse_tabular_csv,
+    csv_source_payload,
+    csv_source_summary,
+    csv_projection_matches,
+    verified_csv_source_text,
+    infer_tabular_schema,
+    tabular_type_name as _type_name,
 )
 from govoplan_core.core.runtime import get_registry
 from govoplan_core.db.base import utcnow
@@ -281,6 +288,7 @@ class SqlTabularSourceProvider:
         description: str | None = None,
         delimiter: str = ",",
         sheet_name: str | None = None,
+        csv_value_mode: CsvValueMode = "legacy_typed",
     ) -> TabularSource:
         db, api_principal = _context(session, principal, WRITE_SCOPE)
         inspection = self._file_adapter().inspect(
@@ -290,6 +298,7 @@ class SqlTabularSourceProvider:
             file_version_id=file_version_id,
             delimiter=delimiter,
             sheet_name=sheet_name,
+            csv_value_mode=csv_value_mode,
         )
         return self._create_origin(
             db,
@@ -353,6 +362,7 @@ class SqlTabularSourceProvider:
                 file_version_id=None,
                 delimiter=str(item.metadata_.get("delimiter") or ","),
                 sheet_name=_clean_optional(item.metadata_.get("sheet_name")),
+                csv_value_mode=str(item.metadata_.get("csv_value_mode") or "legacy_typed"),
             )
         elif item.provider == "postgresql":
             inspection = self._sql_adapter.inspect(
@@ -456,6 +466,20 @@ class SqlTabularSourceProvider:
                 f"Snapshots are limited to {MAX_SNAPSHOT_ROWS:,} rows."
             )
         rows = [_json_row(row) for row in snapshot.rows]
+        csv_payload = None
+        if snapshot.csv_source is not None:
+            if "csv_source" in snapshot.metadata:
+                raise TabularSourceValidationError("csv_source metadata is reserved for verified CSV import evidence.")
+            if snapshot.csv_source.parser_profile != "core.csv.v1":
+                raise TabularSourceValidationError("Unsupported original CSV parser profile.")
+            csv_payload = csv_source_payload(snapshot.csv_source, max_bytes=MAX_SNAPSHOT_BYTES)
+            expected = parse_csv_snapshot(
+                snapshot.csv_source.text,
+                delimiter=snapshot.csv_source.delimiter,
+                value_mode=snapshot.csv_source.value_mode,
+            )
+            if not csv_projection_matches(expected, rows):
+                raise TabularSourceValidationError("Snapshot rows do not match their original CSV source and parsing mode.")
         encoded = json.dumps(rows, sort_keys=True, separators=(",", ":"), default=str).encode("utf-8")
         if len(encoded) > MAX_SNAPSHOT_BYTES:
             raise TabularSourceValidationError(
@@ -487,7 +511,11 @@ class SqlTabularSourceProvider:
             fingerprint=fingerprint,
             row_count=len(rows),
             byte_count=len(encoded),
-            metadata_=dict(snapshot.metadata),
+            metadata_={
+                **dict(snapshot.metadata),
+                **({"csv_source": csv_source_summary(csv_payload)} if csv_payload is not None else {}),
+            },
+            csv_source_=csv_payload,
             created_by=actor_id,
             updated_by=actor_id,
         )
@@ -497,6 +525,15 @@ class SqlTabularSourceProvider:
         db.flush()
         return _source_dto(item)
 
+    def original_csv(self, session: object, principal: object, *, source_ref: str) -> str:
+        db, api_principal = _context(session, principal, READ_SCOPE)
+        item = _source_record(db, tenant_id=api_principal.tenant_id, source_ref=source_ref)
+        if item is None or item.status != "active":
+            raise TabularSourceNotFoundError("Tabular source not found.")
+        if not item.csv_source_:
+            raise TabularSourceNotFoundError("Original CSV was not retained for this source; historical typed snapshots cannot reconstruct it.")
+        return verified_csv_source_text(item.csv_source_, expected_summary=item.metadata_.get("csv_source") or {})
+
     def delete_snapshot(
         self,
         session: object,
@@ -519,35 +556,18 @@ class SqlTabularSourceProvider:
         return _source_dto(item)
 
 
-def parse_csv_snapshot(csv_text: str, *, delimiter: str) -> tuple[Mapping[str, object], ...]:
+def parse_csv_snapshot(csv_text: str, *, delimiter: str, value_mode: CsvValueMode = "legacy_typed") -> tuple[Mapping[str, object], ...]:
     return parse_tabular_csv(
         csv_text,
         delimiter=delimiter,
         max_rows=MAX_SNAPSHOT_ROWS,
+        max_bytes=MAX_SNAPSHOT_BYTES,
+        value_mode=value_mode,
     )
 
 
 def infer_schema(rows: Sequence[Mapping[str, object]]) -> tuple[TabularColumn, ...]:
-    names: list[str] = []
-    for row in rows:
-        for name in row:
-            if name not in names:
-                names.append(name)
-    result: list[TabularColumn] = []
-    for name in names:
-        values = [row.get(name) for row in rows]
-        concrete = [value for value in values if value is not None]
-        data_type = _type_name(concrete[0]) if concrete else "unknown"
-        if any(_type_name(value) != data_type for value in concrete[1:]):
-            data_type = "mixed"
-        result.append(
-            TabularColumn(
-                name=name,
-                data_type=data_type,
-                nullable=len(concrete) != len(values),
-            )
-        )
-    return tuple(result)
+    return infer_tabular_schema(rows, type_name=_type_name)
 
 
 def snapshot_fingerprint(
@@ -717,22 +737,6 @@ def _unsupported_json(value: object) -> object:
     raise TypeError(f"{type(value).__name__} is not JSON serializable")
 
 
-def _type_name(value: object) -> str:
-    if isinstance(value, bool):
-        return "boolean"
-    if isinstance(value, int):
-        return "integer"
-    if isinstance(value, (float, Decimal)):
-        return "number"
-    if isinstance(value, str):
-        return "string"
-    if isinstance(value, list):
-        return "array"
-    if isinstance(value, dict):
-        return "object"
-    return type(value).__name__.lower()
-
-
 def _column_payload(column: TabularColumn) -> dict[str, object]:
     return {
         "name": column.name,