fix(decoder): GzipDecoder fallback should decompress when headers lack gzip content type (AI-Triage PR)

[devin-ai-integration]

fix(decoder): GzipDecoder fallback should decompress when headers lack gzip content type

Summary

One-line fix in create_gzip_decoder(): changes the fallback_parser from gzip_parser.inner_parser (e.g., CsvParser) to gzip_parser (the full GzipParser wrapping the inner parser).

Problem: When GzipDecoder is explicitly configured (e.g., as download_decoder in AsyncRetriever) and the HTTP response lacks Content-Encoding: gzip or Content-Type: application/gzip headers, the _select_parser() method falls back to the inner parser directly (e.g., CsvParser), skipping decompression entirely. This causes UnicodeDecodeError: 'utf-8' codec can't decode byte 0x8b because raw gzip bytes are fed to a text parser.

This is common for S3 pre-signed URL downloads (e.g., CircleCI Usage Export, Amazon Ads reports) where files are gzip-compressed but served as Content-Type: binary/octet-stream.

Fix: Since the user has explicitly declared GzipDecoder, the fallback should still decompress. Change fallback_parser=gzip_parser.inner_parser → fallback_parser=gzip_parser.

Related issues: airbytehq/airbyte#56988, airbytehq/airbyte#66208, airbytehq/oncall#11173

Introduced in airbytehq/airbyte-python-cdk#378.

Review & Testing Checklist for Human

• Verify behavior when response is NOT gzip-compressed and lacks gzip headers: With this change, GzipParser.parse() will be invoked even when there are no gzip headers. If any connector uses GzipDecoder in a context where some responses are genuinely non-gzipped AND lack gzip headers, GzipParser will now fail on those responses instead of gracefully parsing them. Check whether GzipParser.parse() needs a try/except fallback to inner_parser for non-gzip data, or whether this scenario is not possible when the user explicitly configures GzipDecoder.
• Test with a real connector: Validate with CircleCI Usage Export or Amazon Ads connector that downloads gzip files from S3 pre-signed URLs with Content-Type: binary/octet-stream.
• Review the original PR fix: (CDK) (AsyncRetriever) - Use the Nested Decoders to decode the streaming responses, instead of ResponseToFileExtractor #378 intent: The original implementation may have had a reason for the header-based fallback behavior. Confirm with @bazarnov or @maxi297 if needed.

Notes

• Engineers who worked on this code: Baz (oleksandr.bazarnov@globallogic.com, @bazarnov), Maxime Carbonneau-Leclerc (@maxi297)
• Link to Devin run: https://app.devin.ai/sessions/cc34c79fec794f3b8bb894230b50395f
• Requested via AI Triage on oncall#11173

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[github-actions]

👋 Greetings, Airbyte Team Member!

Here are some helpful tips and reminders for your convenience.

💡 Show Tips and Tricks

Testing This CDK Version

You can test this version of the CDK using the following:

# Run the CLI from this branch:
uvx 'git+https://github.com/airbytehq/airbyte-python-cdk.git@devin/1770315462-fix-gzip-decoder-fallback#egg=airbyte-python-cdk[dev]' --help

# Update a connector to use the CDK from this branch ref:
cd airbyte-integrations/connectors/source-example
poe use-cdk-branch devin/1770315462-fix-gzip-decoder-fallback

PR Slash Commands

Airbyte Maintainers can execute the following slash commands on your PR:

• /autofix - Fixes most formatting and linting issues
• /poetry-lock - Updates poetry.lock file
• /test - Runs connector tests with the updated CDK
• /prerelease - Triggers a prerelease publish with default arguments
• /poe build - Regenerate git-committed build artifacts, such as the pydantic models which are generated from the manifest JSON schema in YAML.
• /poe <command> - Runs any poe command in the CDK environment

📚 Show Repo Guidance

Helpful Resources

• CDK API Reference

📝 Edit this welcome message.

[github-actions]

PyTest Results (Fast)

3 856 tests  +1   3 844 ✅ +1   6m 11s ⏱️ -16s
    1 suites ±0      12 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit abed7f6. ± Comparison against base commit 15542de.

[github-actions]

PyTest Results (Full)

3 859 tests  +1   3 847 ✅ +1   11m 0s ⏱️ -1s
    1 suites ±0      12 💤 ±0 
    1 files   ±0       0 ❌ ±0 

Results for commit abed7f6. ± Comparison against base commit 15542de.