fix(declarative): raise CSV field size limit in CsvParser

[devin-ai-integration]

Summary

The declarative CsvParser (sources/declarative/decoders/composite_raw_decoder.py) never called csv.field_size_limit, so any low-code connector reading a CSV response failed on a single value larger than Python's default 131,072 characters:

Error: field larger than field limit (131072)

The file-based CDK parser has raised this to 2**31 since airbytehq/airbyte#36320 (sources/file_based/file_types/csv_parser.py:261-269), but that is a separate parser implementation. Because csv.field_size_limit is process-global, the declarative path's effective limit was whatever the process happened to have — i.e. it depended on whether the file-based parser module had been imported, which is not something a manifest author controls.

This sets the limit explicitly in the declarative parser, using the same value as the file-based parser so the two paths agree:

CSV_FIELD_MAX_BYTES = 2**31
...
csv.field_size_limit(CSV_FIELD_MAX_BYTES)
reader = csv.DictReader(text_data, ...)

Reported by a customer whose source carried a 152,579-character free-text field: the affected records simply did not come through, with nothing in the connection configuration indicating a size cap.

Deliberately out of scope: exposing this as a CsvDecoder manifest option (no declarative_component_schema.yaml change). Happy to add it if reviewers would rather it be configurable per connector than a fixed default.

Test plan

New regression test in unit_tests/sources/declarative/decoders/test_composite_decoder.py decodes a 200 KiB single field value, with the global limit deliberately lowered to 131_072 beforehand (and restored after) so the test fails without the source change. Confirmed the pre-change failure mode is field larger than field limit (131072).

Also ran the declarative decoder suite (62 passed) and the file-based CSV parser suite (69 passed) to check the shared global limit change doesn't regress the other path.

Link to Devin session: https://app.devin.ai/sessions/474c9fe5bfca4e21acce8d128cba3c8a

[devin-ai-integration]

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[github-actions]

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[github-actions]

PyTest Results (Fast)

4 230 tests  +1   4 218 ✅ +1   8m 28s ⏱️ +4s
    1 suites ±0      12 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit 1fe4c7b. ± Comparison against base commit 68bc294.

[github-actions]

PyTest Results (Full)

4 233 tests  +1   4 221 ✅ +1   12m 45s ⏱️ -2s
    1 suites ±0      12 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit 1fe4c7b. ± Comparison against base commit 68bc294.

[devin-ai-integration]

Cross-reference: #1116 was opened from a separate Devin session for the same oncall issue and is a superset of this change (also adds an optional max_field_size property on CsvDecoder and converts the overflow into an actionable AirbyteTracedException). These two should not both land — flagging for maintainers to pick one.

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Devin session