fix: Require batch encoding for BATCH output

[edgarrmondragon]

Summary by Sourcery

Require batch-capable taps to configure the encoding format for BATCH output while keeping it optional for targets.

Bug Fixes:

• Require taps that support BATCH output to declare the batch encoding format in their configuration.

Enhancements:

• Allow targets to keep batch encoding configuration optional because they read encoding details from incoming BATCH messages.
• Share batch configuration schema construction while providing tap- and target-specific encoding requirements.

[edgarrmondragon]

@sourcery-ai title

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

The PR tightens batch output configuration validation by requiring an encoding format, preventing BATCH outputs from being configured without specifying how files should be encoded.

File-Level Changes

Change	Details	Files
Make the batch output encoding format a mandatory configuration field.	Mark the batch output format property as required so invalid configurations are rejected during schema validation. Preserve the existing format description and supported compression/encoding options.	singer_sdk/helpers/capabilities.py

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.47%. Comparing base (43b3563) to head (649134b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3779   +/-   ##
=======================================
  Coverage   94.47%   94.47%           
=======================================
  Files          74       74           
  Lines        6298     6303    +5     
  Branches      771      771           
=======================================
+ Hits         5950     5955    +5     
  Misses        260      260           
  Partials       88       88           

Flag	Coverage Δ
core	83.10% <100.00%> (+0.01%)	⬆️
end-to-end	76.23% <100.00%> (+0.01%)	⬆️
optional-components	45.02% <85.71%> (+0.04%)	⬆️

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[codspeed]

Merging this PR will not alter performance

✅ 14 untouched benchmarks

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_{Comparing fix/BATCH-encoding-format (649134b) with main (6bd41c4)}

[sourcery-ai]

Hey - I've found 1 issue

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="singer_sdk/helpers/capabilities.py" line_range="206-209" />
<code_context>
                         description="Compression format to use for batch files.",
                     ),
                 ),
+                required=True,
             ),
             Property(
</code_context>
<issue_to_address>
**issue (bug_risk):** The new `required=True` applies to the `encoding` property of `batch_config`, not to the nested `format` property. A BATCH configuration containing `"encoding": {}` still passes the generated JSON Schema, so the required batch encoding format is not enforced.

**Triggers:** When BATCH output is enabled and the configuration includes `batch_config.encoding` without `format`.

**Suggested fix:** Set `required=True` on the nested `Property("format", ...)` instead of on the `encoding` property.

```suggestion
                    Property(
                        "format",
                        StringType,
                        title="Batch Encoding Format",
                        description="Format to use for batch files.",
                        required=True,
                    ),
                    Property(
                        "compression",
                        StringType,
                        allowed_values=["gzip", "none"],
                        title="Batch Compression Format",
                        description="Compression format to use for batch files.",
                    ),
                ),
```
</issue_to_address>

Sourcery assessment

Approval pending. 1 finding to address first.

Blocking findings: singer_sdk/helpers/capabilities.py:209

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[edgarrmondragon]

@sourcery-ai review

[sourcery-ai]

Sourcery assessment

Approved.

[sourcery-ai]

Hey - I've found 1 issue

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="singer_sdk/helpers/capabilities.py" line_range="201" />
<code_context>
                         title="Batch Encoding Format",
                         description="Format to use for batch files.",
+                        required=True,
                     ),
                     Property(
                         "compression",
</code_context>
<issue_to_address>
**issue (bug_risk):** Making `format` required only inside the optional `encoding` object does not require it for every `batch_config`. A configuration such as `{"batch_config": {"storage": {"root": "..."}}}` still passes the generated schema because `encoding` itself is optional, then `BatchConfig.from_dict()` raises `TypeError` when BATCH processing constructs `BatchConfig` without an `encoding`.

**Triggers:** When BATCH output is enabled with `batch_config` containing storage or other settings but no `encoding` object.

**Suggested fix:** Make `encoding` required whenever `batch_config` is present, or add a conditional schema requiring `encoding.format` for BATCH configurations.
</issue_to_address>

Sourcery assessment

Approval pending. 1 finding to address first.

Blocking findings: singer_sdk/helpers/capabilities.py:201

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Sourcery withdrew this approval because the latest commits introduced blocking findings.

[sourcery-ai]

Hey - I've found 1 issue

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="singer_sdk/helpers/capabilities.py" line_range="209" />
<code_context>
                         description="Compression format to use for batch files.",
                     ),
                 ),
+                required=True,
             ),
             Property(
</code_context>
<issue_to_address>
**issue (bug_risk):** The schema requires the `encoding` object but leaves its `format` property optional, so a BATCH configuration such as `{"encoding": {"compression": "gzip"}}` passes validation and later `BaseBatchFileEncoding.from_dict` raises `TypeError` because the required `format` constructor argument is missing.

**Triggers:** When BATCH output is enabled and the configuration supplies encoding without a format.

**Suggested fix:** Set `required=True` on the nested `format` Property, rather than only on the `encoding` Property.
</issue_to_address>

Sourcery assessment

Approval pending. 1 finding to address first.

Blocking findings: singer_sdk/helpers/capabilities.py:209

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[sourcery-ai]

Sourcery assessment

Approved.