fix: return Self from Timestamp add/subtract instead of Timestamp

[ajtmccarty]

Problem

Timestamp.add(), Timestamp.subtract() and Timestamp.add_delta() all build their result with self.__class__(...), so at runtime a subclass gets an instance of itself back. The annotations claimed Timestamp.

Any subclass — Infrahub's own Timestamp among them — therefore loses its type as soon as it does arithmetic, and callers have to cast or # type: ignore before touching anything the subclass adds.

Change

Annotate the three methods as returning Self, which is what they already do.

Self is imported from typing_extensions, not typing: typing.Self is 3.11+ and this package supports 3.10 (requires-python = ">=3.10"). The module already imports NotRequired from typing_extensions.

Annotations only — no runtime behaviour changes.

Verification

• uv run invoke format lint-code — clean (ruff + mypy pass; the pre-existing ty unresolved-import diagnostics in unrelated test modules are an incomplete local venv, not this change)
• Confirmed at runtime that a subclass gets its own type back from all three methods

Skipping a changelog fragment — annotation-only change.

🤖 Generated with Claude Code

---

Summary by cubic

Annotates Timestamp.add(), Timestamp.subtract(), and Timestamp.add_delta() to return Self instead of Timestamp, preserving subclass types. Runtime behavior is unchanged; these methods already return self.class.

• Imports Self from typing_extensions to support Python 3.10.
• Improves type checking for subclasses; remove any casts or type: ignore related to these returns.
• Scope: changes limited to infrahub_sdk/timestamp.py.
• No runtime or public API behavior change; no rollout steps required.

^{Written for commit ae7b4d3. Summary will update on new commits.}

[cloudflare-workers-and-pages]

Deploying infrahub-sdk-python with    Cloudflare Pages

Latest commit:	ae7b4d3
Status:	✅  Deploy successful!
Preview URL:	https://80895abf.infrahub-sdk-python.pages.dev
Branch Preview URL:	https://ajtm-timestamp-self-return-t.infrahub-sdk-python.pages.dev

View logs

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##           stable    #1241      +/-   ##
==========================================
- Coverage   83.37%   82.54%   -0.84%     
==========================================
  Files         141      138       -3     
  Lines       13577    12186    -1391     
  Branches     2195     1833     -362     
==========================================
- Hits        11320    10059    -1261     
+ Misses       1642     1568      -74     
+ Partials      615      559      -56     

Flag	Coverage Δ
integration-tests	40.56% <0.00%> (-0.19%)	⬇️
python-3.10	56.34% <0.00%> (-2.11%)	⬇️
python-3.11	56.34% <0.00%> (-2.11%)	⬇️
python-3.12	56.34% <0.00%> (-2.11%)	⬇️
python-3.13	56.32% <0.00%> (-2.12%)	⬇️
python-3.14	56.34% <0.00%> (-2.09%)	⬇️
python-filler-3.12	22.27% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
infrahub_sdk/timestamp.py	82.88% <100.00%> (ø)

... and 9 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.