fix: improve auth session sync reliability

[TimChild]

Takeover of #22 by @PJ-Snap with review fixes applied.

Summary

• Add configurable JWT validation leeway (default 60s) to handle clock drift between Clerk servers and the backend
• Catch ExpiredTokenError alongside InvalidClaimError / MissingClaimError to prevent crashes on expired tokens
• Rewrite ClerkSessionSynchronizer JS for reliability:
  • Use useRef to deduplicate rapid calls while remaining reconnect-safe
  • Request fresh tokens with skipCache to avoid near-expiry cached tokens
  • Handle token retrieval failures gracefully
  • Include all dependencies in useEffect array
• Add unit tests for expired token handling and JS code correctness
• Add pythonpath config for pytest to find custom_components

Review feedback addressed (Copilot review on #22)

Dedupe + retry fixes in clerk_provider.py:

• Only update lastSentRef after a confirmed dispatch so a failed token fetch doesn't poison the dedupe and block later retries.
• Added inFlightRef to prevent overlapping getToken calls when the effect re-fires before the in-flight promise resolves.
• Retry getToken once after a 500 ms delay before clearing the backend session, so transient token-fetch failures don't force a backend logout while Clerk is still signed in.
• On final failure, leave lastSentRef unchanged so the next trigger (reconnect, sign-in toggle, etc.) re-attempts the sync.

Test typecheck fixes:

• # pyright: ignore[reportCallIssue] for the _reflex_internal_init Reflex internal init flag.
• # pyright: ignore[reportAttributeAccessIssue] for accessing .fn on the wrapped EventCallback.

Test plan

• uv run ruff check . passes
• uv run pyright passes (0 errors)
• uv run pytest tests/test_clerk_provider_unit.py -v passes (2/2)
• CI green on push

Supersedes #22. Original work by @PJ-Snap.

[Copilot]

Pull request overview

Improves Clerk auth session synchronization reliability between the Reflex frontend and backend by hardening JWT validation and making the frontend synchronizer more reconnect- and failure-tolerant.

Changes:

• Add configurable JWT validation leeway (default 60s) and handle ExpiredTokenError during claim validation.
• Rewrite ClerkSessionSynchronizer JS to dedupe rapid triggers, request fresh tokens (skipCache), and handle token-fetch failures with retry/clear behavior.
• Add unit tests for expired-token handling and JS regression checks; configure pytest pythonpath for local imports.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
custom_components/reflex_clerk_api/clerk_provider.py	Adds JWT leeway + expired-token handling; rewrites session sync JS logic and React imports.
tests/test_clerk_provider_unit.py	Adds regression/unit tests for leeway + expired-token path and generated JS content.
pyproject.toml	Adds pytest pythonpath to ensure custom_components is importable in tests.

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[TimChild]

Addressed both Copilot race-condition comments in the new commit:

Comment 1 (sign-out blocked by inFlightRef) + Comment 2 (stale set_clerk_session after sign-out) — both stemmed from inFlightRef being a hard gate. Dropped it entirely and replaced with a requestIdRef counter:

• Every effect run with a new desired state increments requestIdRef.current and captures it as myRequestId.
• The sign-out branch now runs unconditionally and immediately.
• The token-fetch promise handlers compare myRequestId === requestIdRef.current before dispatching — so a getToken() that resolves after sign-out (or after any newer effect run) silently drops instead of dispatching a stale set_clerk_session.

This fixes both races: sign-out can no longer be suppressed by an in-flight fetch, and a stale token-fetch result can no longer re-authenticate the backend after sign-out.