Bump mypy from 1.20.1 to 1.20.2

[dependabot]

Bumps mypy from 1.20.1 to 1.20.2.

Changelog

Sourced from mypy's changelog.

Mypy 1.20.1

• Always disable sync in SQLite cache (Ivan Levkivskyi, PR 21184)
• Temporarily skip few base64 tests (Ivan Levkivskyi, PR 21193)
• Revert dict.__or__ typeshed change (Ivan Levkivskyi, PR 21186)
• Fix narrowing for match case with variadic tuples (Shantanu, PR 21192)
• Avoid narrowing type[T] in type calls (Shantanu, PR 21174)
• Fix regression for catching empty tuple in except (Shantanu, PR 21153)
• Fix reachability for frozenset and dict view narrowing (Shantanu, PR 21151)
• Fix narrowing with chained comparison (Shantanu, PR 21150)
• Avoid narrowing to unreachable at module level (Shantanu, PR 21144)
• Allow dangerous identity comparisons to Any typed variables (Shantanu, PR 21142)
• --warn-unused-config should not be a strict flag (Ivan Levkivskyi, PR 21139)

Mypy 1.20.2

• Use WAL with SQLite cache and fix close (Shantanu, PR 21154)
• Adjust SQLite journal mode (Ivan Levkivskyi, PR 21217)
• Correctly aggregate narrowing information on parent expressions (Shantanu, PR 21206)
• Fix regression related to generic callables (Shantanu, PR 21208)
• Fix regression by avoiding widening types in some contexts (Shantanu, PR 21242)
• Fix slicing in non-strict optional mode (Shantanu, PR 21282)
• mypyc: Fix match statement semantics for "or" pattern (Shantanu, PR 21156)
• mypyc: Fix issue with module dunder attributes (Piotr Sawicki, PR 21275)
• Initial support for Python 3.15.0a8 (Marc Mueller, PR 21255)

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

• A5rocks
• Aaron Wieczorek
• Adam Turner
• Ali Hamdan
• asce
• BobTheBuidler
• Brent Westbrook
• Brian Schubert
• bzoracler
• Chris Burroughs
• Christoph Tyralla
• Colin Watson
• Donghoon Nam
• E. M. Bray
• Emma Smith
• Ethan Sarp
• George Ogden
• getzze
• grayjk
• Gregor Riepl
• Ivan Levkivskyi

... (truncated)

Commits

• 145a062 Bump version to 1.20.2
• 81cd492 Fix slicing with nonstrict optional (#21282)
• 908d344 [mypyc] Set dunder attrs when adding module to sys.modules (#21275)
• ba28610 Initial support for Python 3.15.0a8 (#21255)
• 7b0e09f Fix match statement semantics for "or" pattern (#21156)
• 92b74f2 Avoid widening types in conditional_types (#21242)
• 0dcbfaa Fix is_overlapping_types for generic callables (#21208)
• 210f518 Correctly aggregate narrowing information on parent expressions (#21206)
• c34530e Only set journal mode in coordinator (#21217)
• 79a3ec6 Use WAL with SQLite cache, fix close (#21154)
• Additional commits viewable in compare view

Most Recent Ignore Conditions Applied to This Pull Request

Dependency Name	Ignore Conditions
mypy	[>= 1.17.dev0, < 1.18]

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[claude]

Code Review: Bump mypy 1.20.1 → 1.20.2

Overview

Routine Dependabot patch bump of mypy (the static type checker) from 1.20.1 to 1.20.2. The single-line change is in requirements/local.txt, meaning this is a dev/local tooling dependency only — it has no impact on production deployments.

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Assessment

Risk level: Very Low

This is a patch release containing only bug fixes and no new features or breaking changes.

Fixes included in 1.20.2 (relevant to this project)

Fix	Impact
SQLite cache uses WAL mode + proper close	Faster, safer mypy incremental checks on developer machines
Fix regression for generic callables	Prevents false-positive type errors on generic code
Fix narrowing information aggregation on parent expressions	More accurate type narrowing in complex expressions
Fix type widening regression in conditional types	Avoids spurious errors in conditional branches
Fix slicing in non-strict optional mode	Relevant if the project uses non-strict mypy config
mypyc: Fix or pattern in match statements	Only relevant if mypyc compilation is used (not apparent here)
Initial Python 3.15 support	Forward compatibility

What to verify

• The mypy version in requirements/local.txt is the only pin — confirmed by the diff, no divergence with base or production requirements.
• This is a local-only dependency (not in requirements/base.txt or requirements/production.txt), so there is zero production risk.

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Verdict

Approve and merge. This is a safe patch update that fixes type-checker regressions without any API or behavior changes. No new tests are needed — mypy is a dev tool, not application code.