feat!: deprecate in favor of langchain-azure-storage

[darieldatoon]

Summary

Final release of this package. The Azure Blob Storage backend it provides now ships first-party as langchain_azure_storage.deepagents.AzureBlobBackend in langchain-azure-storage (ported in langchain-ai/langchain-azure#783), so this one is being wound down per the hand-off plan in that repo's proposal doc.

Important

Do not merge until langchain-azure-storage 1.2.0 is released.
The published 1.1.1 pins deepagents>=0.6.12,<0.7.0, so it is not a viable migration target for anyone on deepagents 0.7.x. langchain-ai/langchain-azure#878 raises that floor to >=0.7.1; the migration guide in this PR points at 1.2.0 and is only accurate once it ships.

Changes

• Import-time DeprecationWarning in __init__.py pointing at the successor package and the migration guide. stacklevel=2, so it is attributed to the caller's import line.
• README banner + ## Migrating to langchain-azure-storage — a field-by-field table. Not a drop-in swap: the successor dropped AzureBlobConfig in favor of constructor arguments, moved connection strings to a from_connection_string() classmethod, and takes SDK credential objects rather than raw key/token strings. A re-export shim would not have been compatible.
• deepagents>=0.6.1 → >=0.6.1,<0.7.0 (breaking). deepagents 0.7.0 changed BackendProtocol in ways this backend does not implement: write overwrites an existing file instead of returning a file-exists error, delete/adelete is now required (and is visible-but-broken behind a CompositeBackend without it), and GrepResult gained truncated. The previous unbounded pin resolved to that broken combination on a fresh install, so this cap is a bug fix as much as a deprecation signal.
• Metadata: Development Status :: 7 - Inactive, deprecation note in the PyPI summary, Successor package project URL.
• Docstring notice in the module docstring, which is what pdoc renders onto the docs site homepage.
• New unit test asserting the warning fires on import and that the public API survives a reload.

Nothing is yanked and no released version is removed — existing pins keep resolving.

Test plan

• uv run pytest tests/unit_tests → 137 passed
• uv run ruff check ., uv run ruff format --check ., uv run ty check → clean
• Verified the warning surfaces on a plain import deepagents_azure_blob_backend and is attributed to the caller

Follow-up (not in this PR)

After merge and the resulting 0.5.0 publish, in order — both archive steps disable uploads/Actions, so they come last:

1. Confirm the publish and docs workflows went green on the release tag
2. Archive the project on PyPI (settings → archive; non-destructive, keeps releases installable)
3. Close the open Dependabot PRs, remove .github/dependabot.yml, pin a deprecation issue
4. Archive this repository

Known caveat

Python's default warning filters suppress DeprecationWarning when it is raised from an imported module rather than __main__, so many users will not see the notice. UserWarning would always be visible. DeprecationWarning is what the hand-off plan specified, so that is what this PR uses — easy to change if we would rather guarantee visibility.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ba772a0) to head (052f9fd).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #81   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          458       461    +3     
=========================================
+ Hits           458       461    +3     

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