Add per-index exclude-newer overrides for PyPI extra indexes

[pavelzw]

Description

This PR adds support for per-index exclude-newer overrides on PyPI extra indexes, allowing users to customize the package cutoff date for individual indexes. This is particularly useful for private mirrors that do not expose upload-time metadata.

Key Changes:

1. New PypiExtraIndex struct (crates/pixi_manifest/src/pypi/pypi_options.rs):

   • Replaces Vec<Url> with Vec<PypiExtraIndex> to carry both URL and optional per-index exclude-newer override
   • Implements custom serialization to maintain backward compatibility (bare URL strings when no override is set)
   • Provides from_url() constructor for simple cases

2. New IndexExcludeNewer enum (crates/pixi_spec/src/exclude_newer.rs):

   • Allows disabling the cutoff entirely (false) or specifying a custom cutoff for an index
   • Differs from ExcludeNewer by supporting explicit disabling, which is required for indexes without upload-time metadata

3. TOML deserialization support (crates/pixi_manifest/src/toml/pypi_options.rs):

   • Implements custom deserializers for PypiExtraIndex and IndexExcludeNewer
   • Supports both simple URL strings and inline tables: { url = "...", exclude-newer = ... }
   • Validates that exclude-newer = true is rejected with a helpful error message

4. uv integration (crates/pixi_uv_conversions/src/conversions.rs):

   • Maps per-index overrides to uv's ExcludeNewerOverride on each Index
   • Properly handles None (inherit global), Disabled, and custom cutoff values

5. Schema updates (schema/model.py and JSON schemas):

   • Added ExtraIndexInlineTable definition
   • Updated extra-index-urls to accept both URL strings and inline tables
   • Updated documentation with examples and guidance

Example Usage:

[tool.pixi.pypi-options]
extra-index-urls = [
    "https://pypi.org/simple",                                    # inherits global cutoff
    { url = "https://internal/simple", exclude-newer = false },   # disables cutoff
    { url = "https://other/simple", exclude-newer = "2025-01-01" } # custom cutoff
]

How Has This Been Tested?

• Added comprehensive unit tests in crates/pixi_manifest/src/toml/pypi_options.rs:
  • test_deserialize_extra_index_urls_with_exclude_newer: validates parsing of all three formats
  • test_extra_index_exclude_newer_true_is_error: ensures true is rejected with helpful error
  • test_extra_index_missing_url_is_error: validates required url field
• Added integration test in crates/pixi_uv_conversions/src/conversions.rs:
  • test_per_index_exclude_newer_is_applied: verifies per-index overrides are correctly applied to uv indexes
• Updated existing snapshot tests to reflect new PypiExtraIndex structure
• All schema changes validated against model definitions

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes
• I have verified that changes that would impact the JSON schema have been made in schema/model.py

https://claude.ai/code/session_01DbjDfm5GLLeu9pR8XQy7hy