`update-grayskull` does not update `run_constrained` version constraints

[ctcjab]

Summary

The update-grayskull inspection feature updates version constraints in run dependencies but ignores run_constrained dependencies. This causes stale version constraints that can break downstream packages.

Problem

When a package author updates version constraints for optional dependencies in their pyproject.toml, the conda-forge autotick bot:

• ✅ Bumps the package version number
• ✅ Updates the source checksum
• ❌ Does NOT update run_constrained version constraints

This leaves run_constrained with stale constraints that may conflict with other packages.

Root Cause

In conda_forge_tick/update_deps.py:

SECTIONS_TO_PARSE = ["host", "run"]
SECTIONS_TO_UPDATE = ["run"]

The run_constrained section is not included in either constant.

Real-World Example: litellm-feedstock

The litellm package changed its uvicorn constraint on Feb 14, 2026:

• Before: ^0.31.1 (Poetry caret syntax → >=0.31.1,<0.32.0)
• After: >=0.32.1,<1.0.0 (explicit range)

See upstream commit: BerriAI/litellm@81be07a

However, the conda-forge feedstock (litellm-feedstock) still has:

run_constrained:
  - uvicorn >=0.31.1,<0.32.0  # STALE - should be >=0.32.1,<1.0.0

This breaks packages like notebook_intelligence that depend on litellm, because the solver cannot find a uvicorn version satisfying both >=0.32.1 (from other deps) and <0.32.0 (from stale litellm constraint).

Impact

• Downstream packages fail to solve during conda/mamba install
• Users get confusing "Could not solve for environment specs" errors
• Manual PRs are required to fix constraints (e.g., litellm-feedstock#317)

Proposed Solution

Add run_constrained support with constraints-only behavior:

• ✅ Update version constraints for packages that exist in both recipe and grayskull
• ❌ Do NOT add new packages (optional deps are maintainer's choice)
• ❌ Do NOT remove packages (maintainer may have specific reasons)

This conservative approach fixes stale constraints without making unwanted changes to optional dependency lists.

Suggested Implementation

SECTIONS_TO_PARSE = ["host", "run", "run_constrained"]
SECTIONS_TO_UPDATE = ["run"]
SECTIONS_TO_UPDATE_CONSTRAINTS_ONLY = ["run_constrained"]  # New

Then modify _apply_env_dep_comparison() and related functions to support a constraints_only mode that only updates existing packages.

I'm happy to submit a PR implementing this fix.

Environment

• Affected feedstock: litellm-feedstock (and likely others using run_constrained)
• Bot config: bot: inspection: update-grayskull