feat(wren): add cross-dialect type translation to type_mapping

[Bartok9]

What & why

wren.type_mapping already gives us parse_type() / parse_types() to normalize a raw DB type string into sqlglot's canonical form for a single dialect. A common adjacent need in cross-engine modeling (mirroring a Postgres schema into BigQuery, generating MDL for a different target engine, etc.) is to translate a type from one engine's spelling into another's.

This PR adds that as a small, focused companion:

• translate_type(type_str, source_dialect, target_dialect) — parse in source dialect, render in target dialect.
• translate_types(columns, source_dialect, target_dialect, *, type_field="raw_type") — batch variant mirroring parse_types (non-mutating, adds a type key).
• wren utils translate-type and wren utils translate-types CLI commands, matching the existing parse-type / parse-types UX (single via flags, batch via stdin/--input JSON).

Examples:

input	source → target	output
int8	postgres → bigquery	INT64
character varying(255)	postgres → clickhouse	Nullable(String)
INT64	bigquery → postgres	BIGINT
DECIMAL(10,2)	mysql → snowflake	DECIMAL(10, 2)

Parse failures fall back to the original string, matching parse_type's existing contract.

Implementation notes

• Built on sqlglot only — no connector drivers — so it's consistent with the existing module and the new tests run in the lightweight unit tests CI job (no pytest.importorskip guard needed).
• Original input dicts are never mutated; helpers return new lists.
• No new dependencies; no behavior change to existing parse_* paths.

Tests

Added to tests/unit/test_type_mapping.py:

• parametrized translate_type cases (cross-dialect, identity-normalization, unknown-type fallback, empty passthrough)
• translate_types batch tests (adds field, no mutation, custom field, empty list)
• CLI integration tests for translate-type / translate-types

Local run (core/wren, sqlglot 30.12.0):

$ python -m pytest tests/unit/test_type_mapping.py -q
43 passed in 2.27s
$ ruff check src/wren/type_mapping.py src/wren/utils_cli.py tests/unit/test_type_mapping.py
All checks passed!

Summary by CodeRabbit

• New Features
  • Added SQL type translation between dialects for single values and batch inputs.
  • Added CLI commands to translate one type or a JSON list (from a file or stdin).
• Bug Fixes
  • Improved error handling for unreadable input files and invalid JSON, returning a clean nonzero exit with an error message.
  • Unknown/invalid types now safely fall back to the original value.
  • Batch translation avoids mutating the original records.
• Tests
  • Expanded unit and CLI integration coverage for translation, custom type fields, empty inputs, and failure scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: c8008469-15fb-4b3e-8fd6-ae762be6a39f

📥 Commits

Reviewing files that changed from the base of the PR and between dbd361f and 8223481.

📒 Files selected for processing (2)

• core/wren/src/wren/utils_cli.py
• core/wren/tests/unit/test_type_mapping.py

🚧 Files skipped from review as they are similar to previous changes (2)

• core/wren/src/wren/utils_cli.py
• core/wren/tests/unit/test_type_mapping.py

---

Walkthrough

Adds cross-dialect SQL type translation helpers, two CLI commands for single and batch translation, and tests covering translation behavior, fallback, stdin/file input, and error handling.

Changes

SQL Type Translation

Layer / File(s)	Summary
Type translation helpers core/wren/src/wren/type_mapping.py	Adds translate_type for parse/render translation with fallback, and translate_types for batch dict processing with a derived type field.
CLI translation commands core/wren/src/wren/utils_cli.py	Adds translate-type and translate-types commands, including file/stdin loading, error handling, and JSON output.
Translation tests core/wren/tests/unit/test_type_mapping.py	Adds unit tests for translation behavior and CLI tests for both commands, including fallback, stdin input, and file-read errors.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 I hop through types from shore to shore,
One dialect in, one dialect more.
If parsing trips, I keep the old,
And JSON bounces neat and bold.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: adding cross-dialect type translation to type_mapping.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@core/wren/src/wren/utils_cli.py`:
- Around line 103-114: The input parsing in the CLI path around the
`Path.read_text`, `json.loads`, and `json.load` flow only handles
`json.JSONDecodeError`, so file read and encoding failures from `--input` can
still surface as tracebacks. Update the `utils_cli` parsing block to catch
`OSError` and `UnicodeDecodeError` alongside the existing JSON decode handling,
and route them through the same `typer.echo(..., err=True)` plus `typer.Exit(1)`
behavior used for missing files and invalid JSON.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 44c354b1-2779-46d7-af18-a20cceb1753a

📥 Commits

Reviewing files that changed from the base of the PR and between 1be4baa and dbd361f.

📒 Files selected for processing (3)

• core/wren/src/wren/type_mapping.py
• core/wren/src/wren/utils_cli.py
• core/wren/tests/unit/test_type_mapping.py

[Bartok9]

Good catch — fixed in 82234814. Wrapped path.read_text(...) in both translate-types and parse-types so OSError/UnicodeDecodeError now hit the clean typer.Exit(1) path with a could not read file message instead of escaping as a traceback, matching the existing not-found and invalid-JSON handling. Added two regression tests (missing file → exit 1 + no traceback; unreadable path → could not read file + no traceback). Full suite: 45 passed.

[Bartok9]

The one actionable finding (catch OSError/UnicodeDecodeError alongside json.JSONDecodeError on --input file reads) is already addressed in commit 8223481 for both translate-types and parse-types — the path.read_text(...) call is wrapped in a try/except that routes OSError/UnicodeDecodeError through typer.echo(..., err=True) + typer.Exit(1). No further change needed.

[goldmedal]

Thanks @Bartok9 look good 👍